text: // SPDX-License-Identifier: GPL-2.0-only
  /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
   * Copyright (c) 2016 Facebook
   * Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
   */
  #include <uapi/linux/btf.h>
  #include <linux/bpf-cgroup.h>
  #include <linux/kernel.h>
  #include <linux/types.h>
  #include <linux/slab.h>
  #include <linux/bpf.h>
  #include <linux/btf.h>
  #include <linux/bpf_verifier.h>
  #include <linux/filter.h>
  #include <net/netlink.h>
  #include <linux/file.h>
  #include <linux/vmalloc.h>
  #include <linux/stringify.h>
  #include <linux/bsearch.h>
  #include <linux/sort.h>
  #include <linux/perf_event.h>
  #include <linux/ctype.h>
  #include <linux/error-injection.h>
  #include <linux/bpf_lsm.h>
  #include <linux/btf_ids.h>
  
  #include "disasm.h"
  
  static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
  #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
  	[_id] = & _name ## _verifier_ops,
  #define BPF_MAP_TYPE(_id, _ops)
  #define BPF_LINK_TYPE(_id, _name)
  #include <linux/bpf_types.h>
  #undef BPF_PROG_TYPE
  #undef BPF_MAP_TYPE
  #undef BPF_LINK_TYPE
  };
  
  /* bpf_check() is a static code analyzer that walks eBPF program
   * instruction by instruction and updates register/stack state.
   * All paths of conditional branches are analyzed until 'bpf_exit' insn.
   *
   * The first pass is depth-first-search to check that the program is a DAG.
   * It rejects the following programs:
   * - larger than BPF_MAXINSNS insns
   * - if loop is present (detected via back-edge)
   * - unreachable insns exist (shouldn't be a forest. program = one function)
   * - out of bounds or malformed jumps
   * The second pass is all possible path descent from the 1st insn.
   * Since it's analyzing all paths through the program, the length of the
   * analysis is limited to 64k insn, which may be hit even if total number of
   * insn is less then 4K, but there are too many branches that change stack/regs.
   * Number of 'branches to be analyzed' is limited to 1k
   *
   * On entry to each instruction, each register has a type, and the instruction
   * changes the types of the registers depending on instruction semantics.
   * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
   * copied to R1.
   *
   * All registers are 64-bit.
   * R0 - return register
   * R1-R5 argument passing registers
   * R6-R9 callee saved registers
   * R10 - frame pointer read-only
   *
   * At the start of BPF program the register R1 contains a pointer to bpf_context
   * and has type PTR_TO_CTX.
   *
   * Verifier tracks arithmetic operations on pointers in case:
   *    BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
   *    BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
   * 1st insn copies R10 (which has FRAME_PTR) type into R1
   * and 2nd arithmetic instruction is pattern matched to recognize
   * that it wants to construct a pointer to some element within stack.
   * So after 2nd insn, the register R1 has type PTR_TO_STACK
   * (and -20 constant is saved for further stack bounds checking).
   * Meaning that this reg is a pointer to stack plus known immediate constant.
   *
   * Most of the time the registers have SCALAR_VALUE type, which
   * means the register has some value, but it's not a valid pointer.
   * (like pointer plus pointer becomes SCALAR_VALUE type)
   *
   * When verifier sees load or store instructions the type of base register
   * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK, PTR_TO_SOCKET. These are
   * four pointer types recognized by check_mem_access() function.
   *
   * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
   * and the range of [ptr, ptr + map's value_size) is accessible.
   *
   * registers used to pass values to function calls are checked against
   * function argument constraints.
   *
   * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
   * It means that the register type passed to this function must be
   * PTR_TO_STACK and it will be used inside the function as
   * 'pointer to map element key'
   *
   * For example the argument constraints for bpf_map_lookup_elem():
   *   .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
   *   .arg1_type = ARG_CONST_MAP_PTR,
   *   .arg2_type = ARG_PTR_TO_MAP_KEY,
   *
   * ret_type says that this function returns 'pointer to map elem value or null'
   * function expects 1st argument to be a const pointer to 'struct bpf_map' and
   * 2nd argument should be a pointer to stack, which will be used inside
   * the helper function as a pointer to map element key.
   *
   * On the kernel side the helper function looks like:
   * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
   * {
   *    struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
   *    void *key = (void *) (unsigned long) r2;
   *    void *value;
   *
   *    here kernel can access 'key' and 'map' pointers safely, knowing that
   *    [key, key + map->key_size) bytes are valid and were initialized on
   *    the stack of eBPF program.
   * }
   *
   * Corresponding eBPF program may look like:
   *    BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),  // after this insn R2 type is FRAME_PTR
   *    BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
   *    BPF_LD_MAP_FD(BPF_REG_1, map_fd),      // after this insn R1 type is CONST_PTR_TO_MAP
   *    BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
   * here verifier looks at prototype of map_lookup_elem() and sees:
   * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
   * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
   *
   * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
   * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
   * and were initialized prior to this call.
   * If it's ok, then verifier allows this BPF_CALL insn and looks at
   * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
   * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
   * returns either pointer to map value or NULL.
   *
   * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
   * insn, the register holding that pointer in the true branch changes state to
   * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
   * branch. See check_cond_jmp_op().
   *
   * After the call R0 is set to return type of the function and registers R1-R5
   * are set to NOT_INIT to indicate that they are no longer readable.
   *
   * The following reference types represent a potential reference to a kernel
   * resource which, after first being allocated, must be checked and freed by
   * the BPF program:
   * - PTR_TO_SOCKET_OR_NULL, PTR_TO_SOCKET
   *
   * When the verifier sees a helper call return a reference type, it allocates a
   * pointer id for the reference and stores it in the current function state.
   * Similar to the way that PTR_TO_MAP_VALUE_OR_NULL is converted into
   * PTR_TO_MAP_VALUE, PTR_TO_SOCKET_OR_NULL becomes PTR_TO_SOCKET when the type
   * passes through a NULL-check conditional. For the branch wherein the state is
   * changed to CONST_IMM, the verifier releases the reference.
   *
   * For each helper function that allocates a reference, such as
   * bpf_sk_lookup_tcp(), there is a corresponding release function, such as
   * bpf_sk_release(). When a reference type passes into the release function,
   * the verifier also releases the reference. If any unchecked or unreleased
   * reference remains at the end of the program, the verifier rejects it.
   */
  
  /* verifier_state + insn_idx are pushed to stack when branch is encountered */
  struct bpf_verifier_stack_elem {
  	/* verifer state is 'st'
  	 * before processing instruction 'insn_idx'
  	 * and after processing instruction 'prev_insn_idx'
  	 */
  	struct bpf_verifier_state st;
  	int insn_idx;
  	int prev_insn_idx;
  	struct bpf_verifier_stack_elem *next;
  	/* length of verifier log at the time this state was pushed on stack */
  	u32 log_pos;
  };
  
  #define BPF_COMPLEXITY_LIMIT_JMP_SEQ	8192
  #define BPF_COMPLEXITY_LIMIT_STATES	64
  
  #define BPF_MAP_KEY_POISON	(1ULL << 63)
  #define BPF_MAP_KEY_SEEN	(1ULL << 62)
  
  #define BPF_MAP_PTR_UNPRIV	1UL
  #define BPF_MAP_PTR_POISON	((void *)((0xeB9FUL << 1) +	\
  					  POISON_POINTER_DELTA))
  #define BPF_MAP_PTR(X)		((struct bpf_map *)((X) & ~BPF_MAP_PTR_UNPRIV))
  
  static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data *aux)
  {
  	return BPF_MAP_PTR(aux->map_ptr_state) == BPF_MAP_PTR_POISON;
  }
  
  static bool bpf_map_ptr_unpriv(const struct bpf_insn_aux_data *aux)
  {
  	return aux->map_ptr_state & BPF_MAP_PTR_UNPRIV;
  }
  
  static void bpf_map_ptr_store(struct bpf_insn_aux_data *aux,
  			      const struct bpf_map *map, bool unpriv)
  {
  	BUILD_BUG_ON((unsigned long)BPF_MAP_PTR_POISON & BPF_MAP_PTR_UNPRIV);
  	unpriv |= bpf_map_ptr_unpriv(aux);
  	aux->map_ptr_state = (unsigned long)map |
  			     (unpriv ? BPF_MAP_PTR_UNPRIV : 0UL);
  }
  
  static bool bpf_map_key_poisoned(const struct bpf_insn_aux_data *aux)
  {
  	return aux->map_key_state & BPF_MAP_KEY_POISON;
  }
  
  static bool bpf_map_key_unseen(const struct bpf_insn_aux_data *aux)
  {
  	return !(aux->map_key_state & BPF_MAP_KEY_SEEN);
  }
  
  static u64 bpf_map_key_immediate(const struct bpf_insn_aux_data *aux)
  {
  	return aux->map_key_state & ~(BPF_MAP_KEY_SEEN | BPF_MAP_KEY_POISON);
  }
  
  static void bpf_map_key_store(struct bpf_insn_aux_data *aux, u64 state)
  {
  	bool poisoned = bpf_map_key_poisoned(aux);
  
  	aux->map_key_state = state | BPF_MAP_KEY_SEEN |
  			     (poisoned ? BPF_MAP_KEY_POISON : 0ULL);
  }
  
  static bool bpf_pseudo_call(const struct bpf_insn *insn)
  {
  	return insn->code == (BPF_JMP | BPF_CALL) &&
  	       insn->src_reg == BPF_PSEUDO_CALL;
  }
  
  static bool bpf_pseudo_kfunc_call(const struct bpf_insn *insn)
  {
  	return insn->code == (BPF_JMP | BPF_CALL) &&
  	       insn->src_reg == BPF_PSEUDO_KFUNC_CALL;
  }
  
  struct bpf_call_arg_meta {
  	struct bpf_map *map_ptr;
  	bool raw_mode;
  	bool pkt_access;
  	int regno;
  	int access_size;
  	int mem_size;
  	u64 msize_max_value;
  	int ref_obj_id;
  	int map_uid;
  	int func_id;
  	struct btf *btf;
  	u32 btf_id;
  	struct btf *ret_btf;
  	u32 ret_btf_id;
  	u32 subprogno;
  };
  
  struct btf *btf_vmlinux;
  
  static DEFINE_MUTEX(bpf_verifier_lock);
  
  static const struct bpf_line_info *
  find_linfo(const struct bpf_verifier_env *env, u32 insn_off)
  {
  	const struct bpf_line_info *linfo;
  	const struct bpf_prog *prog;
  	u32 i, nr_linfo;
  
  	prog = env->prog;
  	nr_linfo = prog->aux->nr_linfo;
  
  	if (!nr_linfo || insn_off >= prog->len)
  		return NULL;
  
  	linfo = prog->aux->linfo;
  	for (i = 1; i < nr_linfo; i++)
  		if (insn_off < linfo[i].insn_off)
  			break;
  
  	return &linfo[i - 1];
  }
  
  void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt,
  		       va_list args)
  {
  	unsigned int n;
  
  	n = vscnprintf(log->kbuf, BPF_VERIFIER_TMP_LOG_SIZE, fmt, args);
  
  	WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1,
  		  "verifier log line truncated - local buffer too short\n");
  
  	if (log->level == BPF_LOG_KERNEL) {
  		bool newline = n > 0 && log->kbuf[n - 1] == '\n';
  
  		pr_err("BPF: %s%s", log->kbuf, newline ? "" : "\n");
  		return;
  	}
  
  	n = min(log->len_total - log->len_used - 1, n);
  	log->kbuf[n] = '\0';
  	if (!copy_to_user(log->ubuf + log->len_used, log->kbuf, n + 1))
  		log->len_used += n;
  	else
  		log->ubuf = NULL;
  }
  
  static void bpf_vlog_reset(struct bpf_verifier_log *log, u32 new_pos)
  {
  	char zero = 0;
  
  	if (!bpf_verifier_log_needed(log))
  		return;
  
  	log->len_used = new_pos;
  	if (put_user(zero, log->ubuf + new_pos))
  		log->ubuf = NULL;
  }
  
  /* log_level controls verbosity level of eBPF verifier.
   * bpf_verifier_log_write() is used to dump the verification trace to the log,
   * so the user can figure out what's wrong with the program
   */
  __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,
  					   const char *fmt, ...)
  {
  	va_list args;
  
  	if (!bpf_verifier_log_needed(&env->log))
  		return;
  
  	va_start(args, fmt);
  	bpf_verifier_vlog(&env->log, fmt, args);
  	va_end(args);
  }
  EXPORT_SYMBOL_GPL(bpf_verifier_log_write);
  
  __printf(2, 3) static void verbose(void *private_data, const char *fmt, ...)
  {
  	struct bpf_verifier_env *env = private_data;
  	va_list args;
  
  	if (!bpf_verifier_log_needed(&env->log))
  		return;
  
  	va_start(args, fmt);
  	bpf_verifier_vlog(&env->log, fmt, args);
  	va_end(args);
  }
  
  __printf(2, 3) void bpf_log(struct bpf_verifier_log *log,
  			    const char *fmt, ...)
  {
  	va_list args;
  
  	if (!bpf_verifier_log_needed(log))
  		return;
  
  	va_start(args, fmt);
  	bpf_verifier_vlog(log, fmt, args);
  	va_end(args);
  }
  
  static const char *ltrim(const char *s)
  {
  	while (isspace(*s))
  		s++;
  
  	return s;
  }
  
  __printf(3, 4) static void verbose_linfo(struct bpf_verifier_env *env,
  					 u32 insn_off,
  					 const char *prefix_fmt, ...)
  {
  	const struct bpf_line_info *linfo;
  
  	if (!bpf_verifier_log_needed(&env->log))
  		return;
  
  	linfo = find_linfo(env, insn_off);
  	if (!linfo || linfo == env->prev_linfo)
  		return;
  
  	if (prefix_fmt) {
  		va_list args;
  
  		va_start(args, prefix_fmt);
  		bpf_verifier_vlog(&env->log, prefix_fmt, args);
  		va_end(args);
  	}
  
  	verbose(env, "%s\n",
  		ltrim(btf_name_by_offset(env->prog->aux->btf,
  					 linfo->line_off)));
  
  	env->prev_linfo = linfo;
  }
  
  static void verbose_invalid_scalar(struct bpf_verifier_env *env,
  				   struct bpf_reg_state *reg,
  				   struct tnum *range, const char *ctx,
  				   const char *reg_name)
  {
  	char tn_buf[48];
  
  	verbose(env, "At %s the register %s ", ctx, reg_name);
  	if (!tnum_is_unknown(reg->var_off)) {
  		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  		verbose(env, "has value %s", tn_buf);
  	} else {
  		verbose(env, "has unknown scalar value");
  	}
  	tnum_strn(tn_buf, sizeof(tn_buf), *range);
  	verbose(env, " should have been in %s\n", tn_buf);
  }
  
  static bool type_is_pkt_pointer(enum bpf_reg_type type)
  {
  	return type == PTR_TO_PACKET ||
  	       type == PTR_TO_PACKET_META;
  }
  
  static bool type_is_sk_pointer(enum bpf_reg_type type)
  {
  	return type == PTR_TO_SOCKET ||
  		type == PTR_TO_SOCK_COMMON ||
  		type == PTR_TO_TCP_SOCK ||
  		type == PTR_TO_XDP_SOCK;
  }
  
  static bool reg_type_not_null(enum bpf_reg_type type)
  {
  	return type == PTR_TO_SOCKET ||
  		type == PTR_TO_TCP_SOCK ||
  		type == PTR_TO_MAP_VALUE ||
  		type == PTR_TO_MAP_KEY ||
  		type == PTR_TO_SOCK_COMMON;
  }
  
  static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg)
  {
  	return reg->type == PTR_TO_MAP_VALUE &&
  		map_value_has_spin_lock(reg->map_ptr);
  }
  
  static bool reg_type_may_be_refcounted_or_null(enum bpf_reg_type type)
  {
  	return base_type(type) == PTR_TO_SOCKET ||
  		base_type(type) == PTR_TO_TCP_SOCK ||
  		base_type(type) == PTR_TO_MEM ||
  		base_type(type) == PTR_TO_BTF_ID;
  }
  
  static bool type_is_rdonly_mem(u32 type)
  {
  	return type & MEM_RDONLY;
  }
  
  static bool arg_type_may_be_refcounted(enum bpf_arg_type type)
  {
  	return type == ARG_PTR_TO_SOCK_COMMON;
  }
  
  static bool type_may_be_null(u32 type)
  {
  	return type & PTR_MAYBE_NULL;
  }
  
  /* Determine whether the function releases some resources allocated by another
   * function call. The first reference type argument will be assumed to be
   * released by release_reference().
   */
  static bool is_release_function(enum bpf_func_id func_id)
  {
  	return func_id == BPF_FUNC_sk_release ||
  	       func_id == BPF_FUNC_ringbuf_submit ||
  	       func_id == BPF_FUNC_ringbuf_discard;
  }
  
  static bool may_be_acquire_function(enum bpf_func_id func_id)
  {
  	return func_id == BPF_FUNC_sk_lookup_tcp ||
  		func_id == BPF_FUNC_sk_lookup_udp ||
  		func_id == BPF_FUNC_skc_lookup_tcp ||
  		func_id == BPF_FUNC_map_lookup_elem ||
  	        func_id == BPF_FUNC_ringbuf_reserve;
  }
  
  static bool is_acquire_function(enum bpf_func_id func_id,
  				const struct bpf_map *map)
  {
  	enum bpf_map_type map_type = map ? map->map_type : BPF_MAP_TYPE_UNSPEC;
  
  	if (func_id == BPF_FUNC_sk_lookup_tcp ||
  	    func_id == BPF_FUNC_sk_lookup_udp ||
  	    func_id == BPF_FUNC_skc_lookup_tcp ||
  	    func_id == BPF_FUNC_ringbuf_reserve)
  		return true;
  
  	if (func_id == BPF_FUNC_map_lookup_elem &&
  	    (map_type == BPF_MAP_TYPE_SOCKMAP ||
  	     map_type == BPF_MAP_TYPE_SOCKHASH))
  		return true;
  
  	return false;
  }
  
  static bool is_ptr_cast_function(enum bpf_func_id func_id)
  {
  	return func_id == BPF_FUNC_tcp_sock ||
  		func_id == BPF_FUNC_sk_fullsock ||
  		func_id == BPF_FUNC_skc_to_tcp_sock ||
  		func_id == BPF_FUNC_skc_to_tcp6_sock ||
  		func_id == BPF_FUNC_skc_to_udp6_sock ||
  		func_id == BPF_FUNC_skc_to_tcp_timewait_sock ||
  		func_id == BPF_FUNC_skc_to_tcp_request_sock;
  }
  
  static bool is_cmpxchg_insn(const struct bpf_insn *insn)
  {
  	return BPF_CLASS(insn->code) == BPF_STX &&
  	       BPF_MODE(insn->code) == BPF_ATOMIC &&
  	       insn->imm == BPF_CMPXCHG;
  }
  
  /* string representation of 'enum bpf_reg_type'
   *
   * Note that reg_type_str() can not appear more than once in a single verbose()
   * statement.
   */
  static const char *reg_type_str(struct bpf_verifier_env *env,
  				enum bpf_reg_type type)
  {
  	char postfix[16] = {0}, prefix[32] = {0};
  	static const char * const str[] = {
  		[NOT_INIT]		= "?",
  		[SCALAR_VALUE]		= "scalar",
  		[PTR_TO_CTX]		= "ctx",
  		[CONST_PTR_TO_MAP]	= "map_ptr",
  		[PTR_TO_MAP_VALUE]	= "map_value",
  		[PTR_TO_STACK]		= "fp",
  		[PTR_TO_PACKET]		= "pkt",
  		[PTR_TO_PACKET_META]	= "pkt_meta",
  		[PTR_TO_PACKET_END]	= "pkt_end",
  		[PTR_TO_FLOW_KEYS]	= "flow_keys",
  		[PTR_TO_SOCKET]		= "sock",
  		[PTR_TO_SOCK_COMMON]	= "sock_common",
  		[PTR_TO_TCP_SOCK]	= "tcp_sock",
  		[PTR_TO_TP_BUFFER]	= "tp_buffer",
  		[PTR_TO_XDP_SOCK]	= "xdp_sock",
  		[PTR_TO_BTF_ID]		= "ptr_",
  		[PTR_TO_MEM]		= "mem",
  		[PTR_TO_BUF]		= "buf",
  		[PTR_TO_FUNC]		= "func",
  		[PTR_TO_MAP_KEY]	= "map_key",
  	};
  
  	if (type & PTR_MAYBE_NULL) {
  		if (base_type(type) == PTR_TO_BTF_ID)
  			strncpy(postfix, "or_null_", 16);
  		else
  			strncpy(postfix, "_or_null", 16);
  	}
  
  	if (type & MEM_RDONLY)
  		strncpy(prefix, "rdonly_", 32);
  	if (type & MEM_ALLOC)
  		strncpy(prefix, "alloc_", 32);
  	if (type & MEM_USER)
  		strncpy(prefix, "user_", 32);
  	if (type & MEM_PERCPU)
  		strncpy(prefix, "percpu_", 32);
  
  	snprintf(env->type_str_buf, TYPE_STR_BUF_LEN, "%s%s%s",
  		 prefix, str[base_type(type)], postfix);
  	return env->type_str_buf;
  }
  
  static char slot_type_char[] = {
  	[STACK_INVALID]	= '?',
  	[STACK_SPILL]	= 'r',
  	[STACK_MISC]	= 'm',
  	[STACK_ZERO]	= '0',
  };
  
  static void print_liveness(struct bpf_verifier_env *env,
  			   enum bpf_reg_liveness live)
  {
  	if (live & (REG_LIVE_READ | REG_LIVE_WRITTEN | REG_LIVE_DONE))
  	    verbose(env, "_");
  	if (live & REG_LIVE_READ)
  		verbose(env, "r");
  	if (live & REG_LIVE_WRITTEN)
  		verbose(env, "w");
  	if (live & REG_LIVE_DONE)
  		verbose(env, "D");
  }
  
  static struct bpf_func_state *func(struct bpf_verifier_env *env,
  				   const struct bpf_reg_state *reg)
  {
  	struct bpf_verifier_state *cur = env->cur_state;
  
  	return cur->frame[reg->frameno];
  }
  
  static const char *kernel_type_name(const struct btf* btf, u32 id)
  {
  	return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off);
  }
  
  static void mark_reg_scratched(struct bpf_verifier_env *env, u32 regno)
  {
  	env->scratched_regs |= 1U << regno;
  }
  
  static void mark_stack_slot_scratched(struct bpf_verifier_env *env, u32 spi)
  {
  	env->scratched_stack_slots |= 1ULL << spi;
  }
  
  static bool reg_scratched(const struct bpf_verifier_env *env, u32 regno)
  {
  	return (env->scratched_regs >> regno) & 1;
  }
  
  static bool stack_slot_scratched(const struct bpf_verifier_env *env, u64 regno)
  {
  	return (env->scratched_stack_slots >> regno) & 1;
  }
  
  static bool verifier_state_scratched(const struct bpf_verifier_env *env)
  {
  	return env->scratched_regs || env->scratched_stack_slots;
  }
  
  static void mark_verifier_state_clean(struct bpf_verifier_env *env)
  {
  	env->scratched_regs = 0U;
  	env->scratched_stack_slots = 0ULL;
  }
  
  /* Used for printing the entire verifier state. */
  static void mark_verifier_state_scratched(struct bpf_verifier_env *env)
  {
  	env->scratched_regs = ~0U;
  	env->scratched_stack_slots = ~0ULL;
  }
  
  /* The reg state of a pointer or a bounded scalar was saved when
   * it was spilled to the stack.
   */
  static bool is_spilled_reg(const struct bpf_stack_state *stack)
  {
  	return stack->slot_type[BPF_REG_SIZE - 1] == STACK_SPILL;
  }
  
  static void scrub_spilled_slot(u8 *stype)
  {
  	if (*stype != STACK_INVALID)
  		*stype = STACK_MISC;
  }
  
  static void print_verifier_state(struct bpf_verifier_env *env,
  				 const struct bpf_func_state *state,
  				 bool print_all)
  {
  	const struct bpf_reg_state *reg;
  	enum bpf_reg_type t;
  	int i;
  
  	if (state->frameno)
  		verbose(env, " frame%d:", state->frameno);
  	for (i = 0; i < MAX_BPF_REG; i++) {
  		reg = &state->regs[i];
  		t = reg->type;
  		if (t == NOT_INIT)
  			continue;
  		if (!print_all && !reg_scratched(env, i))
  			continue;
  		verbose(env, " R%d", i);
  		print_liveness(env, reg->live);
  		verbose(env, "=");
  		if (t == SCALAR_VALUE && reg->precise)
  			verbose(env, "P");
  		if ((t == SCALAR_VALUE || t == PTR_TO_STACK) &&
  		    tnum_is_const(reg->var_off)) {
  			/* reg->off should be 0 for SCALAR_VALUE */
  			verbose(env, "%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t));
  			verbose(env, "%lld", reg->var_off.value + reg->off);
  		} else {
  			const char *sep = "";
  
  			verbose(env, "%s", reg_type_str(env, t));
  			if (base_type(t) == PTR_TO_BTF_ID)
  				verbose(env, "%s", kernel_type_name(reg->btf, reg->btf_id));
  			verbose(env, "(");
  /*
   * _a stands for append, was shortened to avoid multiline statements below.
   * This macro is used to output a comma separated list of attributes.
   */
  #define verbose_a(fmt, ...) ({ verbose(env, "%s" fmt, sep, __VA_ARGS__); sep = ","; })
  
  			if (reg->id)
  				verbose_a("id=%d", reg->id);
  			if (reg_type_may_be_refcounted_or_null(t) && reg->ref_obj_id)
  				verbose_a("ref_obj_id=%d", reg->ref_obj_id);
  			if (t != SCALAR_VALUE)
  				verbose_a("off=%d", reg->off);
  			if (type_is_pkt_pointer(t))
  				verbose_a("r=%d", reg->range);
  			else if (base_type(t) == CONST_PTR_TO_MAP ||
  				 base_type(t) == PTR_TO_MAP_KEY ||
  				 base_type(t) == PTR_TO_MAP_VALUE)
  				verbose_a("ks=%d,vs=%d",
  					  reg->map_ptr->key_size,
  					  reg->map_ptr->value_size);
  			if (tnum_is_const(reg->var_off)) {
  				/* Typically an immediate SCALAR_VALUE, but
  				 * could be a pointer whose offset is too big
  				 * for reg->off
  				 */
  				verbose_a("imm=%llx", reg->var_off.value);
  			} else {
  				if (reg->smin_value != reg->umin_value &&
  				    reg->smin_value != S64_MIN)
  					verbose_a("smin=%lld", (long long)reg->smin_value);
  				if (reg->smax_value != reg->umax_value &&
  				    reg->smax_value != S64_MAX)
  					verbose_a("smax=%lld", (long long)reg->smax_value);
  				if (reg->umin_value != 0)
  					verbose_a("umin=%llu", (unsigned long long)reg->umin_value);
  				if (reg->umax_value != U64_MAX)
  					verbose_a("umax=%llu", (unsigned long long)reg->umax_value);
  				if (!tnum_is_unknown(reg->var_off)) {
  					char tn_buf[48];
  
  					tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  					verbose_a("var_off=%s", tn_buf);
  				}
  				if (reg->s32_min_value != reg->smin_value &&
  				    reg->s32_min_value != S32_MIN)
  					verbose_a("s32_min=%d", (int)(reg->s32_min_value));
  				if (reg->s32_max_value != reg->smax_value &&
  				    reg->s32_max_value != S32_MAX)
  					verbose_a("s32_max=%d", (int)(reg->s32_max_value));
  				if (reg->u32_min_value != reg->umin_value &&
  				    reg->u32_min_value != U32_MIN)
  					verbose_a("u32_min=%d", (int)(reg->u32_min_value));
  				if (reg->u32_max_value != reg->umax_value &&
  				    reg->u32_max_value != U32_MAX)
  					verbose_a("u32_max=%d", (int)(reg->u32_max_value));
  			}
  #undef verbose_a
  
  			verbose(env, ")");
  		}
  	}
  	for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
  		char types_buf[BPF_REG_SIZE + 1];
  		bool valid = false;
  		int j;
  
  		for (j = 0; j < BPF_REG_SIZE; j++) {
  			if (state->stack[i].slot_type[j] != STACK_INVALID)
  				valid = true;
  			types_buf[j] = slot_type_char[
  					state->stack[i].slot_type[j]];
  		}
  		types_buf[BPF_REG_SIZE] = 0;
  		if (!valid)
  			continue;
  		if (!print_all && !stack_slot_scratched(env, i))
  			continue;
  		verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE);
  		print_liveness(env, state->stack[i].spilled_ptr.live);
  		if (is_spilled_reg(&state->stack[i])) {
  			reg = &state->stack[i].spilled_ptr;
  			t = reg->type;
  			verbose(env, "=%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t));
  			if (t == SCALAR_VALUE && reg->precise)
  				verbose(env, "P");
  			if (t == SCALAR_VALUE && tnum_is_const(reg->var_off))
  				verbose(env, "%lld", reg->var_off.value + reg->off);
  		} else {
  			verbose(env, "=%s", types_buf);
  		}
  	}
  	if (state->acquired_refs && state->refs[0].id) {
  		verbose(env, " refs=%d", state->refs[0].id);
  		for (i = 1; i < state->acquired_refs; i++)
  			if (state->refs[i].id)
  				verbose(env, ",%d", state->refs[i].id);
  	}
  	if (state->in_callback_fn)
  		verbose(env, " cb");
  	if (state->in_async_callback_fn)
  		verbose(env, " async_cb");
  	verbose(env, "\n");
  	mark_verifier_state_clean(env);
  }
  
  static inline u32 vlog_alignment(u32 pos)
  {
  	return round_up(max(pos + BPF_LOG_MIN_ALIGNMENT / 2, BPF_LOG_ALIGNMENT),
  			BPF_LOG_MIN_ALIGNMENT) - pos - 1;
  }
  
  static void print_insn_state(struct bpf_verifier_env *env,
  			     const struct bpf_func_state *state)
  {
  	if (env->prev_log_len && env->prev_log_len == env->log.len_used) {
  		/* remove new line character */
  		bpf_vlog_reset(&env->log, env->prev_log_len - 1);
  		verbose(env, "%*c;", vlog_alignment(env->prev_insn_print_len), ' ');
  	} else {
  		verbose(env, "%d:", env->insn_idx);
  	}
  	print_verifier_state(env, state, false);
  }
  
  /* copy array src of length n * size bytes to dst. dst is reallocated if it's too
   * small to hold src. This is different from krealloc since we don't want to preserve
   * the contents of dst.
   *
   * Leaves dst untouched if src is NULL or length is zero. Returns NULL if memory could
   * not be allocated.
   */
  static void *copy_array(void *dst, const void *src, size_t n, size_t size, gfp_t flags)
  {
  	size_t bytes;
  
  	if (ZERO_OR_NULL_PTR(src))
  		goto out;
  
  	if (unlikely(check_mul_overflow(n, size, &bytes)))
  		return NULL;
  
  	if (ksize(dst) < bytes) {
  		kfree(dst);
  		dst = kmalloc_track_caller(bytes, flags);
  		if (!dst)
  			return NULL;
  	}
  
  	memcpy(dst, src, bytes);
  out:
  	return dst ? dst : ZERO_SIZE_PTR;
  }
  
  /* resize an array from old_n items to new_n items. the array is reallocated if it's too
   * small to hold new_n items. new items are zeroed out if the array grows.
   *
   * Contrary to krealloc_array, does not free arr if new_n is zero.
   */
  static void *realloc_array(void *arr, size_t old_n, size_t new_n, size_t size)
  {
  	if (!new_n || old_n == new_n)
  		goto out;
  
  	arr = krealloc_array(arr, new_n, size, GFP_KERNEL);
  	if (!arr)
  		return NULL;
  
  	if (new_n > old_n)
  		memset(arr + old_n * size, 0, (new_n - old_n) * size);
  
  out:
  	return arr ? arr : ZERO_SIZE_PTR;
  }
  
  static int copy_reference_state(struct bpf_func_state *dst, const struct bpf_func_state *src)
  {
  	dst->refs = copy_array(dst->refs, src->refs, src->acquired_refs,
  			       sizeof(struct bpf_reference_state), GFP_KERNEL);
  	if (!dst->refs)
  		return -ENOMEM;
  
  	dst->acquired_refs = src->acquired_refs;
  	return 0;
  }
  
  static int copy_stack_state(struct bpf_func_state *dst, const struct bpf_func_state *src)
  {
  	size_t n = src->allocated_stack / BPF_REG_SIZE;
  
  	dst->stack = copy_array(dst->stack, src->stack, n, sizeof(struct bpf_stack_state),
  				GFP_KERNEL);
  	if (!dst->stack)
  		return -ENOMEM;
  
  	dst->allocated_stack = src->allocated_stack;
  	return 0;
  }
  
  static int resize_reference_state(struct bpf_func_state *state, size_t n)
  {
  	state->refs = realloc_array(state->refs, state->acquired_refs, n,
  				    sizeof(struct bpf_reference_state));
  	if (!state->refs)
  		return -ENOMEM;
  
  	state->acquired_refs = n;
  	return 0;
  }
  
  static int grow_stack_state(struct bpf_func_state *state, int size)
  {
  	size_t old_n = state->allocated_stack / BPF_REG_SIZE, n = size / BPF_REG_SIZE;
  
  	if (old_n >= n)
  		return 0;
  
  	state->stack = realloc_array(state->stack, old_n, n, sizeof(struct bpf_stack_state));
  	if (!state->stack)
  		return -ENOMEM;
  
  	state->allocated_stack = size;
  	return 0;
  }
  
  /* Acquire a pointer id from the env and update the state->refs to include
   * this new pointer reference.
   * On success, returns a valid pointer id to associate with the register
   * On failure, returns a negative errno.
   */
  static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx)
  {
  	struct bpf_func_state *state = cur_func(env);
  	int new_ofs = state->acquired_refs;
  	int id, err;
  
  	err = resize_reference_state(state, state->acquired_refs + 1);
  	if (err)
  		return err;
  	id = ++env->id_gen;
  	state->refs[new_ofs].id = id;
  	state->refs[new_ofs].insn_idx = insn_idx;
  
  	return id;
  }
  
  /* release function corresponding to acquire_reference_state(). Idempotent. */
  static int release_reference_state(struct bpf_func_state *state, int ptr_id)
  {
  	int i, last_idx;
  
  	last_idx = state->acquired_refs - 1;
  	for (i = 0; i < state->acquired_refs; i++) {
  		if (state->refs[i].id == ptr_id) {
  			if (last_idx && i != last_idx)
  				memcpy(&state->refs[i], &state->refs[last_idx],
  				       sizeof(*state->refs));
  			memset(&state->refs[last_idx], 0, sizeof(*state->refs));
  			state->acquired_refs--;
  			return 0;
  		}
  	}
  	return -EINVAL;
  }
  
  static void free_func_state(struct bpf_func_state *state)
  {
  	if (!state)
  		return;
  	kfree(state->refs);
  	kfree(state->stack);
  	kfree(state);
  }
  
  static void clear_jmp_history(struct bpf_verifier_state *state)
  {
  	kfree(state->jmp_history);
  	state->jmp_history = NULL;
  	state->jmp_history_cnt = 0;
  }
  
  static void free_verifier_state(struct bpf_verifier_state *state,
  				bool free_self)
  {
  	int i;
  
  	for (i = 0; i <= state->curframe; i++) {
  		free_func_state(state->frame[i]);
  		state->frame[i] = NULL;
  	}
  	clear_jmp_history(state);
  	if (free_self)
  		kfree(state);
  }
  
  /* copy verifier state from src to dst growing dst stack space
   * when necessary to accommodate larger src stack
   */
  static int copy_func_state(struct bpf_func_state *dst,
  			   const struct bpf_func_state *src)
  {
  	int err;
  
  	memcpy(dst, src, offsetof(struct bpf_func_state, acquired_refs));
  	err = copy_reference_state(dst, src);
  	if (err)
  		return err;
  	return copy_stack_state(dst, src);
  }
  
  static int copy_verifier_state(struct bpf_verifier_state *dst_state,
  			       const struct bpf_verifier_state *src)
  {
  	struct bpf_func_state *dst;
  	int i, err;
  
  	dst_state->jmp_history = copy_array(dst_state->jmp_history, src->jmp_history,
  					    src->jmp_history_cnt, sizeof(struct bpf_idx_pair),
  					    GFP_USER);
  	if (!dst_state->jmp_history)
  		return -ENOMEM;
  	dst_state->jmp_history_cnt = src->jmp_history_cnt;
  
  	/* if dst has more stack frames then src frame, free them */
  	for (i = src->curframe + 1; i <= dst_state->curframe; i++) {
  		free_func_state(dst_state->frame[i]);
  		dst_state->frame[i] = NULL;
  	}
  	dst_state->speculative = src->speculative;
  	dst_state->curframe = src->curframe;
  	dst_state->active_spin_lock = src->active_spin_lock;
  	dst_state->branches = src->branches;
  	dst_state->parent = src->parent;
  	dst_state->first_insn_idx = src->first_insn_idx;
  	dst_state->last_insn_idx = src->last_insn_idx;
  	for (i = 0; i <= src->curframe; i++) {
  		dst = dst_state->frame[i];
  		if (!dst) {
  			dst = kzalloc(sizeof(*dst), GFP_KERNEL);
  			if (!dst)
  				return -ENOMEM;
  			dst_state->frame[i] = dst;
  		}
  		err = copy_func_state(dst, src->frame[i]);
  		if (err)
  			return err;
  	}
  	return 0;
  }
  
  static void update_branch_counts(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
  {
  	while (st) {
  		u32 br = --st->branches;
  
  		/* WARN_ON(br > 1) technically makes sense here,
  		 * but see comment in push_stack(), hence:
  		 */
  		WARN_ONCE((int)br < 0,
  			  "BUG update_branch_counts:branches_to_explore=%d\n",
  			  br);
  		if (br)
  			break;
  		st = st->parent;
  	}
  }
  
  static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx,
  		     int *insn_idx, bool pop_log)
  {
  	struct bpf_verifier_state *cur = env->cur_state;
  	struct bpf_verifier_stack_elem *elem, *head = env->head;
  	int err;
  
  	if (env->head == NULL)
  		return -ENOENT;
  
  	if (cur) {
  		err = copy_verifier_state(cur, &head->st);
  		if (err)
  			return err;
  	}
  	if (pop_log)
  		bpf_vlog_reset(&env->log, head->log_pos);
  	if (insn_idx)
  		*insn_idx = head->insn_idx;
  	if (prev_insn_idx)
  		*prev_insn_idx = head->prev_insn_idx;
  	elem = head->next;
  	free_verifier_state(&head->st, false);
  	kfree(head);
  	env->head = elem;
  	env->stack_size--;
  	return 0;
  }
  
  static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
  					     int insn_idx, int prev_insn_idx,
  					     bool speculative)
  {
  	struct bpf_verifier_state *cur = env->cur_state;
  	struct bpf_verifier_stack_elem *elem;
  	int err;
  
  	elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
  	if (!elem)
  		goto err;
  
  	elem->insn_idx = insn_idx;
  	elem->prev_insn_idx = prev_insn_idx;
  	elem->next = env->head;
  	elem->log_pos = env->log.len_used;
  	env->head = elem;
  	env->stack_size++;
  	err = copy_verifier_state(&elem->st, cur);
  	if (err)
  		goto err;
  	elem->st.speculative |= speculative;
  	if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
  		verbose(env, "The sequence of %d jumps is too complex.\n",
  			env->stack_size);
  		goto err;
  	}
  	if (elem->st.parent) {
  		++elem->st.parent->branches;
  		/* WARN_ON(branches > 2) technically makes sense here,
  		 * but
  		 * 1. speculative states will bump 'branches' for non-branch
  		 * instructions
  		 * 2. is_state_visited() heuristics may decide not to create
  		 * a new state for a sequence of branches and all such current
  		 * and cloned states will be pointing to a single parent state
  		 * which might have large 'branches' count.
  		 */
  	}
  	return &elem->st;
  err:
  	free_verifier_state(env->cur_state, true);
  	env->cur_state = NULL;
  	/* pop all elements and return */
  	while (!pop_stack(env, NULL, NULL, false));
  	return NULL;
  }
  
  #define CALLER_SAVED_REGS 6
  static const int caller_saved[CALLER_SAVED_REGS] = {
  	BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
  };
  
  static void __mark_reg_not_init(const struct bpf_verifier_env *env,
  				struct bpf_reg_state *reg);
  
  /* This helper doesn't clear reg->id */
  static void ___mark_reg_known(struct bpf_reg_state *reg, u64 imm)
  {
  	reg->var_off = tnum_const(imm);
  	reg->smin_value = (s64)imm;
  	reg->smax_value = (s64)imm;
  	reg->umin_value = imm;
  	reg->umax_value = imm;
  
  	reg->s32_min_value = (s32)imm;
  	reg->s32_max_value = (s32)imm;
  	reg->u32_min_value = (u32)imm;
  	reg->u32_max_value = (u32)imm;
  }
  
  /* Mark the unknown part of a register (variable offset or scalar value) as
   * known to have the value @imm.
   */
  static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm)
  {
  	/* Clear id, off, and union(map_ptr, range) */
  	memset(((u8 *)reg) + sizeof(reg->type), 0,
  	       offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type));
  	___mark_reg_known(reg, imm);
  }
  
  static void __mark_reg32_known(struct bpf_reg_state *reg, u64 imm)
  {
  	reg->var_off = tnum_const_subreg(reg->var_off, imm);
  	reg->s32_min_value = (s32)imm;
  	reg->s32_max_value = (s32)imm;
  	reg->u32_min_value = (u32)imm;
  	reg->u32_max_value = (u32)imm;
  }
  
  /* Mark the 'variable offset' part of a register as zero.  This should be
   * used only on registers holding a pointer type.
   */
  static void __mark_reg_known_zero(struct bpf_reg_state *reg)
  {
  	__mark_reg_known(reg, 0);
  }
  
  static void __mark_reg_const_zero(struct bpf_reg_state *reg)
  {
  	__mark_reg_known(reg, 0);
  	reg->type = SCALAR_VALUE;
  }
  
  static void mark_reg_known_zero(struct bpf_verifier_env *env,
  				struct bpf_reg_state *regs, u32 regno)
  {
  	if (WARN_ON(regno >= MAX_BPF_REG)) {
  		verbose(env, "mark_reg_known_zero(regs, %u)\n", regno);
  		/* Something bad happened, let's kill all regs */
  		for (regno = 0; regno < MAX_BPF_REG; regno++)
  			__mark_reg_not_init(env, regs + regno);
  		return;
  	}
  	__mark_reg_known_zero(regs + regno);
  }
  
  static void mark_ptr_not_null_reg(struct bpf_reg_state *reg)
  {
  	if (base_type(reg->type) == PTR_TO_MAP_VALUE) {
  		const struct bpf_map *map = reg->map_ptr;
  
  		if (map->inner_map_meta) {
  			reg->type = CONST_PTR_TO_MAP;
  			reg->map_ptr = map->inner_map_meta;
  			/* transfer reg's id which is unique for every map_lookup_elem
  			 * as UID of the inner map.
  			 */
  			if (map_value_has_timer(map->inner_map_meta))
  				reg->map_uid = reg->id;
  		} else if (map->map_type == BPF_MAP_TYPE_XSKMAP) {
  			reg->type = PTR_TO_XDP_SOCK;
  		} else if (map->map_type == BPF_MAP_TYPE_SOCKMAP ||
  			   map->map_type == BPF_MAP_TYPE_SOCKHASH) {
  			reg->type = PTR_TO_SOCKET;
  		} else {
  			reg->type = PTR_TO_MAP_VALUE;
  		}
  		return;
  	}
  
  	reg->type &= ~PTR_MAYBE_NULL;
  }
  
  static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg)
  {
  	return type_is_pkt_pointer(reg->type);
  }
  
  static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg)
  {
  	return reg_is_pkt_pointer(reg) ||
  	       reg->type == PTR_TO_PACKET_END;
  }
  
  /* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */
  static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg,
  				    enum bpf_reg_type which)
  {
  	/* The register can already have a range from prior markings.
  	 * This is fine as long as it hasn't been advanced from its
  	 * origin.
  	 */
  	return reg->type == which &&
  	       reg->id == 0 &&
  	       reg->off == 0 &&
  	       tnum_equals_const(reg->var_off, 0);
  }
  
  /* Reset the min/max bounds of a register */
  static void __mark_reg_unbounded(struct bpf_reg_state *reg)
  {
  	reg->smin_value = S64_MIN;
  	reg->smax_value = S64_MAX;
  	reg->umin_value = 0;
  	reg->umax_value = U64_MAX;
  
  	reg->s32_min_value = S32_MIN;
  	reg->s32_max_value = S32_MAX;
  	reg->u32_min_value = 0;
  	reg->u32_max_value = U32_MAX;
  }
  
  static void __mark_reg64_unbounded(struct bpf_reg_state *reg)
  {
  	reg->smin_value = S64_MIN;
  	reg->smax_value = S64_MAX;
  	reg->umin_value = 0;
  	reg->umax_value = U64_MAX;
  }
  
  static void __mark_reg32_unbounded(struct bpf_reg_state *reg)
  {
  	reg->s32_min_value = S32_MIN;
  	reg->s32_max_value = S32_MAX;
  	reg->u32_min_value = 0;
  	reg->u32_max_value = U32_MAX;
  }
  
  static void __update_reg32_bounds(struct bpf_reg_state *reg)
  {
  	struct tnum var32_off = tnum_subreg(reg->var_off);
  
  	/* min signed is max(sign bit) | min(other bits) */
  	reg->s32_min_value = max_t(s32, reg->s32_min_value,
  			var32_off.value | (var32_off.mask & S32_MIN));
  	/* max signed is min(sign bit) | max(other bits) */
  	reg->s32_max_value = min_t(s32, reg->s32_max_value,
  			var32_off.value | (var32_off.mask & S32_MAX));
  	reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)var32_off.value);
  	reg->u32_max_value = min(reg->u32_max_value,
  				 (u32)(var32_off.value | var32_off.mask));
  }
  
  static void __update_reg64_bounds(struct bpf_reg_state *reg)
  {
  	/* min signed is max(sign bit) | min(other bits) */
  	reg->smin_value = max_t(s64, reg->smin_value,
  				reg->var_off.value | (reg->var_off.mask & S64_MIN));
  	/* max signed is min(sign bit) | max(other bits) */
  	reg->smax_value = min_t(s64, reg->smax_value,
  				reg->var_off.value | (reg->var_off.mask & S64_MAX));
  	reg->umin_value = max(reg->umin_value, reg->var_off.value);
  	reg->umax_value = min(reg->umax_value,
  			      reg->var_off.value | reg->var_off.mask);
  }
  
  static void __update_reg_bounds(struct bpf_reg_state *reg)
  {
  	__update_reg32_bounds(reg);
  	__update_reg64_bounds(reg);
  }
  
  /* Uses signed min/max values to inform unsigned, and vice-versa */
  static void __reg32_deduce_bounds(struct bpf_reg_state *reg)
  {
  	/* Learn sign from signed bounds.
  	 * If we cannot cross the sign boundary, then signed and unsigned bounds
  	 * are the same, so combine.  This works even in the negative case, e.g.
  	 * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
  	 */
  	if (reg->s32_min_value >= 0 || reg->s32_max_value < 0) {
  		reg->s32_min_value = reg->u32_min_value =
  			max_t(u32, reg->s32_min_value, reg->u32_min_value);
  		reg->s32_max_value = reg->u32_max_value =
  			min_t(u32, reg->s32_max_value, reg->u32_max_value);
  		return;
  	}
  	/* Learn sign from unsigned bounds.  Signed bounds cross the sign
  	 * boundary, so we must be careful.
  	 */
  	if ((s32)reg->u32_max_value >= 0) {
  		/* Positive.  We can't learn anything from the smin, but smax
  		 * is positive, hence safe.
  		 */
  		reg->s32_min_value = reg->u32_min_value;
  		reg->s32_max_value = reg->u32_max_value =
  			min_t(u32, reg->s32_max_value, reg->u32_max_value);
  	} else if ((s32)reg->u32_min_value < 0) {
  		/* Negative.  We can't learn anything from the smax, but smin
  		 * is negative, hence safe.
  		 */
  		reg->s32_min_value = reg->u32_min_value =
  			max_t(u32, reg->s32_min_value, reg->u32_min_value);
  		reg->s32_max_value = reg->u32_max_value;
  	}
  }
  
  static void __reg64_deduce_bounds(struct bpf_reg_state *reg)
  {
  	/* Learn sign from signed bounds.
  	 * If we cannot cross the sign boundary, then signed and unsigned bounds
  	 * are the same, so combine.  This works even in the negative case, e.g.
  	 * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
  	 */
  	if (reg->smin_value >= 0 || reg->smax_value < 0) {
  		reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value,
  							  reg->umin_value);
  		reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value,
  							  reg->umax_value);
  		return;
  	}
  	/* Learn sign from unsigned bounds.  Signed bounds cross the sign
  	 * boundary, so we must be careful.
  	 */
  	if ((s64)reg->umax_value >= 0) {
  		/* Positive.  We can't learn anything from the smin, but smax
  		 * is positive, hence safe.
  		 */
  		reg->smin_value = reg->umin_value;
  		reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value,
  							  reg->umax_value);
  	} else if ((s64)reg->umin_value < 0) {
  		/* Negative.  We can't learn anything from the smax, but smin
  		 * is negative, hence safe.
  		 */
  		reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value,
  							  reg->umin_value);
  		reg->smax_value = reg->umax_value;
  	}
  }
  
  static void __reg_deduce_bounds(struct bpf_reg_state *reg)
  {
  	__reg32_deduce_bounds(reg);
  	__reg64_deduce_bounds(reg);
  }
  
  /* Attempts to improve var_off based on unsigned min/max information */
  static void __reg_bound_offset(struct bpf_reg_state *reg)
  {
  	struct tnum var64_off = tnum_intersect(reg->var_off,
  					       tnum_range(reg->umin_value,
  							  reg->umax_value));
  	struct tnum var32_off = tnum_intersect(tnum_subreg(reg->var_off),
  						tnum_range(reg->u32_min_value,
  							   reg->u32_max_value));
  
  	reg->var_off = tnum_or(tnum_clear_subreg(var64_off), var32_off);
  }
  
  static bool __reg32_bound_s64(s32 a)
  {
  	return a >= 0 && a <= S32_MAX;
  }
  
  static void __reg_assign_32_into_64(struct bpf_reg_state *reg)
  {
  	reg->umin_value = reg->u32_min_value;
  	reg->umax_value = reg->u32_max_value;
  
  	/* Attempt to pull 32-bit signed bounds into 64-bit bounds but must
  	 * be positive otherwise set to worse case bounds and refine later
  	 * from tnum.
  	 */
  	if (__reg32_bound_s64(reg->s32_min_value) &&
  	    __reg32_bound_s64(reg->s32_max_value)) {
  		reg->smin_value = reg->s32_min_value;
  		reg->smax_value = reg->s32_max_value;
  	} else {
  		reg->smin_value = 0;
  		reg->smax_value = U32_MAX;
  	}
  }
  
  static void __reg_combine_32_into_64(struct bpf_reg_state *reg)
  {
  	/* special case when 64-bit register has upper 32-bit register
  	 * zeroed. Typically happens after zext or <<32, >>32 sequence
  	 * allowing us to use 32-bit bounds directly,
  	 */
  	if (tnum_equals_const(tnum_clear_subreg(reg->var_off), 0)) {
  		__reg_assign_32_into_64(reg);
  	} else {
  		/* Otherwise the best we can do is push lower 32bit known and
  		 * unknown bits into register (var_off set from jmp logic)
  		 * then learn as much as possible from the 64-bit tnum
  		 * known and unknown bits. The previous smin/smax bounds are
  		 * invalid here because of jmp32 compare so mark them unknown
  		 * so they do not impact tnum bounds calculation.
  		 */
  		__mark_reg64_unbounded(reg);
  		__update_reg_bounds(reg);
  	}
  
  	/* Intersecting with the old var_off might have improved our bounds
  	 * slightly.  e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
  	 * then new var_off is (0; 0x7f...fc) which improves our umax.
  	 */
  	__reg_deduce_bounds(reg);
  	__reg_bound_offset(reg);
  	__update_reg_bounds(reg);
  }
  
  static bool __reg64_bound_s32(s64 a)
  {
  	return a >= S32_MIN && a <= S32_MAX;
  }
  
  static bool __reg64_bound_u32(u64 a)
  {
  	return a >= U32_MIN && a <= U32_MAX;
  }
  
  static void __reg_combine_64_into_32(struct bpf_reg_state *reg)
  {
  	__mark_reg32_unbounded(reg);
  
  	if (__reg64_bound_s32(reg->smin_value) && __reg64_bound_s32(reg->smax_value)) {
  		reg->s32_min_value = (s32)reg->smin_value;
  		reg->s32_max_value = (s32)reg->smax_value;
  	}
  	if (__reg64_bound_u32(reg->umin_value) && __reg64_bound_u32(reg->umax_value)) {
  		reg->u32_min_value = (u32)reg->umin_value;
  		reg->u32_max_value = (u32)reg->umax_value;
  	}
  
  	/* Intersecting with the old var_off might have improved our bounds
  	 * slightly.  e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
  	 * then new var_off is (0; 0x7f...fc) which improves our umax.
  	 */
  	__reg_deduce_bounds(reg);
  	__reg_bound_offset(reg);
  	__update_reg_bounds(reg);
  }
  
  /* Mark a register as having a completely unknown (scalar) value. */
  static void __mark_reg_unknown(const struct bpf_verifier_env *env,
  			       struct bpf_reg_state *reg)
  {
  	/*
  	 * Clear type, id, off, and union(map_ptr, range) and
  	 * padding between 'type' and union
  	 */
  	memset(reg, 0, offsetof(struct bpf_reg_state, var_off));
  	reg->type = SCALAR_VALUE;
  	reg->var_off = tnum_unknown;
  	reg->frameno = 0;
  	reg->precise = env->subprog_cnt > 1 || !env->bpf_capable;
  	__mark_reg_unbounded(reg);
  }
  
  static void mark_reg_unknown(struct bpf_verifier_env *env,
  			     struct bpf_reg_state *regs, u32 regno)
  {
  	if (WARN_ON(regno >= MAX_BPF_REG)) {
  		verbose(env, "mark_reg_unknown(regs, %u)\n", regno);
  		/* Something bad happened, let's kill all regs except FP */
  		for (regno = 0; regno < BPF_REG_FP; regno++)
  			__mark_reg_not_init(env, regs + regno);
  		return;
  	}
  	__mark_reg_unknown(env, regs + regno);
  }
  
  static void __mark_reg_not_init(const struct bpf_verifier_env *env,
  				struct bpf_reg_state *reg)
  {
  	__mark_reg_unknown(env, reg);
  	reg->type = NOT_INIT;
  }
  
  static void mark_reg_not_init(struct bpf_verifier_env *env,
  			      struct bpf_reg_state *regs, u32 regno)
  {
  	if (WARN_ON(regno >= MAX_BPF_REG)) {
  		verbose(env, "mark_reg_not_init(regs, %u)\n", regno);
  		/* Something bad happened, let's kill all regs except FP */
  		for (regno = 0; regno < BPF_REG_FP; regno++)
  			__mark_reg_not_init(env, regs + regno);
  		return;
  	}
  	__mark_reg_not_init(env, regs + regno);
  }
  
  static void mark_btf_ld_reg(struct bpf_verifier_env *env,
  			    struct bpf_reg_state *regs, u32 regno,
  			    enum bpf_reg_type reg_type,
  			    struct btf *btf, u32 btf_id,
  			    enum bpf_type_flag flag)
  {
  	if (reg_type == SCALAR_VALUE) {
  		mark_reg_unknown(env, regs, regno);
  		return;
  	}
  	mark_reg_known_zero(env, regs, regno);
  	regs[regno].type = PTR_TO_BTF_ID | flag;
  	regs[regno].btf = btf;
  	regs[regno].btf_id = btf_id;
  }
  
  #define DEF_NOT_SUBREG	(0)
  static void init_reg_state(struct bpf_verifier_env *env,
  			   struct bpf_func_state *state)
  {
  	struct bpf_reg_state *regs = state->regs;
  	int i;
  
  	for (i = 0; i < MAX_BPF_REG; i++) {
  		mark_reg_not_init(env, regs, i);
  		regs[i].live = REG_LIVE_NONE;
  		regs[i].parent = NULL;
  		regs[i].subreg_def = DEF_NOT_SUBREG;
  	}
  
  	/* frame pointer */
  	regs[BPF_REG_FP].type = PTR_TO_STACK;
  	mark_reg_known_zero(env, regs, BPF_REG_FP);
  	regs[BPF_REG_FP].frameno = state->frameno;
  }
  
  #define BPF_MAIN_FUNC (-1)
  static void init_func_state(struct bpf_verifier_env *env,
  			    struct bpf_func_state *state,
  			    int callsite, int frameno, int subprogno)
  {
  	state->callsite = callsite;
  	state->frameno = frameno;
  	state->subprogno = subprogno;
  	init_reg_state(env, state);
  	mark_verifier_state_scratched(env);
  }
  
  /* Similar to push_stack(), but for async callbacks */
  static struct bpf_verifier_state *push_async_cb(struct bpf_verifier_env *env,
  						int insn_idx, int prev_insn_idx,
  						int subprog)
  {
  	struct bpf_verifier_stack_elem *elem;
  	struct bpf_func_state *frame;
  
  	elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
  	if (!elem)
  		goto err;
  
  	elem->insn_idx = insn_idx;
  	elem->prev_insn_idx = prev_insn_idx;
  	elem->next = env->head;
  	elem->log_pos = env->log.len_used;
  	env->head = elem;
  	env->stack_size++;
  	if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
  		verbose(env,
  			"The sequence of %d jumps is too complex for async cb.\n",
  			env->stack_size);
  		goto err;
  	}
  	/* Unlike push_stack() do not copy_verifier_state().
  	 * The caller state doesn't matter.
  	 * This is async callback. It starts in a fresh stack.
  	 * Initialize it similar to do_check_common().
  	 */
  	elem->st.branches = 1;
  	frame = kzalloc(sizeof(*frame), GFP_KERNEL);
  	if (!frame)
  		goto err;
  	init_func_state(env, frame,
  			BPF_MAIN_FUNC /* callsite */,
  			0 /* frameno within this callchain */,
  			subprog /* subprog number within this prog */);
  	elem->st.frame[0] = frame;
  	return &elem->st;
  err:
  	free_verifier_state(env->cur_state, true);
  	env->cur_state = NULL;
  	/* pop all elements and return */
  	while (!pop_stack(env, NULL, NULL, false));
  	return NULL;
  }
  
  
  enum reg_arg_type {
  	SRC_OP,		/* register is used as source operand */
  	DST_OP,		/* register is used as destination operand */
  	DST_OP_NO_MARK	/* same as above, check only, don't mark */
  };
  
  static int cmp_subprogs(const void *a, const void *b)
  {
  	return ((struct bpf_subprog_info *)a)->start -
  	       ((struct bpf_subprog_info *)b)->start;
  }
  
  static int find_subprog(struct bpf_verifier_env *env, int off)
  {
  	struct bpf_subprog_info *p;
  
  	p = bsearch(&off, env->subprog_info, env->subprog_cnt,
  		    sizeof(env->subprog_info[0]), cmp_subprogs);
  	if (!p)
  		return -ENOENT;
  	return p - env->subprog_info;
  
  }
  
  static int add_subprog(struct bpf_verifier_env *env, int off)
  {
  	int insn_cnt = env->prog->len;
  	int ret;
  
  	if (off >= insn_cnt || off < 0) {
  		verbose(env, "call to invalid destination\n");
  		return -EINVAL;
  	}
  	ret = find_subprog(env, off);
  	if (ret >= 0)
  		return ret;
  	if (env->subprog_cnt >= BPF_MAX_SUBPROGS) {
  		verbose(env, "too many subprograms\n");
  		return -E2BIG;
  	}
  	/* determine subprog starts. The end is one before the next starts */
  	env->subprog_info[env->subprog_cnt++].start = off;
  	sort(env->subprog_info, env->subprog_cnt,
  	     sizeof(env->subprog_info[0]), cmp_subprogs, NULL);
  	return env->subprog_cnt - 1;
  }
  
  #define MAX_KFUNC_DESCS 256
  #define MAX_KFUNC_BTFS	256
  
  struct bpf_kfunc_desc {
  	struct btf_func_model func_model;
  	u32 func_id;
  	s32 imm;
  	u16 offset;
  };
  
  struct bpf_kfunc_btf {
  	struct btf *btf;
  	struct module *module;
  	u16 offset;
  };
  
  struct bpf_kfunc_desc_tab {
  	struct bpf_kfunc_desc descs[MAX_KFUNC_DESCS];
  	u32 nr_descs;
  };
  
  struct bpf_kfunc_btf_tab {
  	struct bpf_kfunc_btf descs[MAX_KFUNC_BTFS];
  	u32 nr_descs;
  };
  
  static int kfunc_desc_cmp_by_id_off(const void *a, const void *b)
  {
  	const struct bpf_kfunc_desc *d0 = a;
  	const struct bpf_kfunc_desc *d1 = b;
  
  	/* func_id is not greater than BTF_MAX_TYPE */
  	return d0->func_id - d1->func_id ?: d0->offset - d1->offset;
  }
  
  static int kfunc_btf_cmp_by_off(const void *a, const void *b)
  {
  	const struct bpf_kfunc_btf *d0 = a;
  	const struct bpf_kfunc_btf *d1 = b;
  
  	return d0->offset - d1->offset;
  }
  
  static const struct bpf_kfunc_desc *
  find_kfunc_desc(const struct bpf_prog *prog, u32 func_id, u16 offset)
  {
  	struct bpf_kfunc_desc desc = {
  		.func_id = func_id,
  		.offset = offset,
  	};
  	struct bpf_kfunc_desc_tab *tab;
  
  	tab = prog->aux->kfunc_tab;
  	return bsearch(&desc, tab->descs, tab->nr_descs,
  		       sizeof(tab->descs[0]), kfunc_desc_cmp_by_id_off);
  }
  
  static struct btf *__find_kfunc_desc_btf(struct bpf_verifier_env *env,
  					 s16 offset)
  {
  	struct bpf_kfunc_btf kf_btf = { .offset = offset };
  	struct bpf_kfunc_btf_tab *tab;
  	struct bpf_kfunc_btf *b;
  	struct module *mod;
  	struct btf *btf;
  	int btf_fd;
  
  	tab = env->prog->aux->kfunc_btf_tab;
  	b = bsearch(&kf_btf, tab->descs, tab->nr_descs,
  		    sizeof(tab->descs[0]), kfunc_btf_cmp_by_off);
  	if (!b) {
  		if (tab->nr_descs == MAX_KFUNC_BTFS) {
  			verbose(env, "too many different module BTFs\n");
  			return ERR_PTR(-E2BIG);
  		}
  
  		if (bpfptr_is_null(env->fd_array)) {
  			verbose(env, "kfunc offset > 0 without fd_array is invalid\n");
  			return ERR_PTR(-EPROTO);
  		}
  
  		if (copy_from_bpfptr_offset(&btf_fd, env->fd_array,
  					    offset * sizeof(btf_fd),
  					    sizeof(btf_fd)))
  			return ERR_PTR(-EFAULT);
  
  		btf = btf_get_by_fd(btf_fd);
  		if (IS_ERR(btf)) {
  			verbose(env, "invalid module BTF fd specified\n");
  			return btf;
  		}
  
  		if (!btf_is_module(btf)) {
  			verbose(env, "BTF fd for kfunc is not a module BTF\n");
  			btf_put(btf);
  			return ERR_PTR(-EINVAL);
  		}
  
  		mod = btf_try_get_module(btf);
  		if (!mod) {
  			btf_put(btf);
  			return ERR_PTR(-ENXIO);
  		}
  
  		b = &tab->descs[tab->nr_descs++];
  		b->btf = btf;
  		b->module = mod;
  		b->offset = offset;
  
  		sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
  		     kfunc_btf_cmp_by_off, NULL);
  	}
  	return b->btf;
  }
  
  void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab)
  {
  	if (!tab)
  		return;
  
  	while (tab->nr_descs--) {
  		module_put(tab->descs[tab->nr_descs].module);
  		btf_put(tab->descs[tab->nr_descs].btf);
  	}
  	kfree(tab);
  }
  
  static struct btf *find_kfunc_desc_btf(struct bpf_verifier_env *env,
  				       u32 func_id, s16 offset)
  {
  	if (offset) {
  		if (offset < 0) {
  			/* In the future, this can be allowed to increase limit
  			 * of fd index into fd_array, interpreted as u16.
  			 */
  			verbose(env, "negative offset disallowed for kernel module function call\n");
  			return ERR_PTR(-EINVAL);
  		}
  
  		return __find_kfunc_desc_btf(env, offset);
  	}
  	return btf_vmlinux ?: ERR_PTR(-ENOENT);
  }
  
  static int add_kfunc_call(struct bpf_verifier_env *env, u32 func_id, s16 offset)
  {
  	const struct btf_type *func, *func_proto;
  	struct bpf_kfunc_btf_tab *btf_tab;
  	struct bpf_kfunc_desc_tab *tab;
  	struct bpf_prog_aux *prog_aux;
  	struct bpf_kfunc_desc *desc;
  	const char *func_name;
  	struct btf *desc_btf;
  	unsigned long call_imm;
  	unsigned long addr;
  	int err;
  
  	prog_aux = env->prog->aux;
  	tab = prog_aux->kfunc_tab;
  	btf_tab = prog_aux->kfunc_btf_tab;
  	if (!tab) {
  		if (!btf_vmlinux) {
  			verbose(env, "calling kernel function is not supported without CONFIG_DEBUG_INFO_BTF\n");
  			return -ENOTSUPP;
  		}
  
  		if (!env->prog->jit_requested) {
  			verbose(env, "JIT is required for calling kernel function\n");
  			return -ENOTSUPP;
  		}
  
  		if (!bpf_jit_supports_kfunc_call()) {
  			verbose(env, "JIT does not support calling kernel function\n");
  			return -ENOTSUPP;
  		}
  
  		if (!env->prog->gpl_compatible) {
  			verbose(env, "cannot call kernel function from non-GPL compatible program\n");
  			return -EINVAL;
  		}
  
  		tab = kzalloc(sizeof(*tab), GFP_KERNEL);
  		if (!tab)
  			return -ENOMEM;
  		prog_aux->kfunc_tab = tab;
  	}
  
  	/* func_id == 0 is always invalid, but instead of returning an error, be
  	 * conservative and wait until the code elimination pass before returning
  	 * error, so that invalid calls that get pruned out can be in BPF programs
  	 * loaded from userspace.  It is also required that offset be untouched
  	 * for such calls.
  	 */
  	if (!func_id && !offset)
  		return 0;
  
  	if (!btf_tab && offset) {
  		btf_tab = kzalloc(sizeof(*btf_tab), GFP_KERNEL);
  		if (!btf_tab)
  			return -ENOMEM;
  		prog_aux->kfunc_btf_tab = btf_tab;
  	}
  
  	desc_btf = find_kfunc_desc_btf(env, func_id, offset);
  	if (IS_ERR(desc_btf)) {
  		verbose(env, "failed to find BTF for kernel function\n");
  		return PTR_ERR(desc_btf);
  	}
  
  	if (find_kfunc_desc(env->prog, func_id, offset))
  		return 0;
  
  	if (tab->nr_descs == MAX_KFUNC_DESCS) {
  		verbose(env, "too many different kernel function calls\n");
  		return -E2BIG;
  	}
  
  	func = btf_type_by_id(desc_btf, func_id);
  	if (!func || !btf_type_is_func(func)) {
  		verbose(env, "kernel btf_id %u is not a function\n",
  			func_id);
  		return -EINVAL;
  	}
  	func_proto = btf_type_by_id(desc_btf, func->type);
  	if (!func_proto || !btf_type_is_func_proto(func_proto)) {
  		verbose(env, "kernel function btf_id %u does not have a valid func_proto\n",
  			func_id);
  		return -EINVAL;
  	}
  
  	func_name = btf_name_by_offset(desc_btf, func->name_off);
  	addr = kallsyms_lookup_name(func_name);
  	if (!addr) {
  		verbose(env, "cannot find address for kernel function %s\n",
  			func_name);
  		return -EINVAL;
  	}
  
  	call_imm = BPF_CALL_IMM(addr);
  	/* Check whether or not the relative offset overflows desc->imm */
  	if ((unsigned long)(s32)call_imm != call_imm) {
  		verbose(env, "address of kernel function %s is out of range\n",
  			func_name);
  		return -EINVAL;
  	}
  
  	desc = &tab->descs[tab->nr_descs++];
  	desc->func_id = func_id;
  	desc->imm = call_imm;
  	desc->offset = offset;
  	err = btf_distill_func_proto(&env->log, desc_btf,
  				     func_proto, func_name,
  				     &desc->func_model);
  	if (!err)
  		sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
  		     kfunc_desc_cmp_by_id_off, NULL);
  	return err;
  }
  
  static int kfunc_desc_cmp_by_imm(const void *a, const void *b)
  {
  	const struct bpf_kfunc_desc *d0 = a;
  	const struct bpf_kfunc_desc *d1 = b;
  
  	if (d0->imm > d1->imm)
  		return 1;
  	else if (d0->imm < d1->imm)
  		return -1;
  	return 0;
  }
  
  static void sort_kfunc_descs_by_imm(struct bpf_prog *prog)
  {
  	struct bpf_kfunc_desc_tab *tab;
  
  	tab = prog->aux->kfunc_tab;
  	if (!tab)
  		return;
  
  	sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
  	     kfunc_desc_cmp_by_imm, NULL);
  }
  
  bool bpf_prog_has_kfunc_call(const struct bpf_prog *prog)
  {
  	return !!prog->aux->kfunc_tab;
  }
  
  const struct btf_func_model *
  bpf_jit_find_kfunc_model(const struct bpf_prog *prog,
  			 const struct bpf_insn *insn)
  {
  	const struct bpf_kfunc_desc desc = {
  		.imm = insn->imm,
  	};
  	const struct bpf_kfunc_desc *res;
  	struct bpf_kfunc_desc_tab *tab;
  
  	tab = prog->aux->kfunc_tab;
  	res = bsearch(&desc, tab->descs, tab->nr_descs,
  		      sizeof(tab->descs[0]), kfunc_desc_cmp_by_imm);
  
  	return res ? &res->func_model : NULL;
  }
  
  static int add_subprog_and_kfunc(struct bpf_verifier_env *env)
  {
  	struct bpf_subprog_info *subprog = env->subprog_info;
  	struct bpf_insn *insn = env->prog->insnsi;
  	int i, ret, insn_cnt = env->prog->len;
  
  	/* Add entry function. */
  	ret = add_subprog(env, 0);
  	if (ret)
  		return ret;
  
  	for (i = 0; i < insn_cnt; i++, insn++) {
  		if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn) &&
  		    !bpf_pseudo_kfunc_call(insn))
  			continue;
  
  		if (!env->bpf_capable) {
  			verbose(env, "loading/calling other bpf or kernel functions are allowed for CAP_BPF and CAP_SYS_ADMIN\n");
  			return -EPERM;
  		}
  
  		if (bpf_pseudo_func(insn) || bpf_pseudo_call(insn))
  			ret = add_subprog(env, i + insn->imm + 1);
  		else
  			ret = add_kfunc_call(env, insn->imm, insn->off);
  
  		if (ret < 0)
  			return ret;
  	}
  
  	/* Add a fake 'exit' subprog which could simplify subprog iteration
  	 * logic. 'subprog_cnt' should not be increased.
  	 */
  	subprog[env->subprog_cnt].start = insn_cnt;
  
  	if (env->log.level & BPF_LOG_LEVEL2)
  		for (i = 0; i < env->subprog_cnt; i++)
  			verbose(env, "func#%d @%d\n", i, subprog[i].start);
  
  	return 0;
  }
  
  static int check_subprogs(struct bpf_verifier_env *env)
  {
  	int i, subprog_start, subprog_end, off, cur_subprog = 0;
  	struct bpf_subprog_info *subprog = env->subprog_info;
  	struct bpf_insn *insn = env->prog->insnsi;
  	int insn_cnt = env->prog->len;
  
  	/* now check that all jumps are within the same subprog */
  	subprog_start = subprog[cur_subprog].start;
  	subprog_end = subprog[cur_subprog + 1].start;
  	for (i = 0; i < insn_cnt; i++) {
  		u8 code = insn[i].code;
  
  		if (code == (BPF_JMP | BPF_CALL) &&
  		    insn[i].imm == BPF_FUNC_tail_call &&
  		    insn[i].src_reg != BPF_PSEUDO_CALL)
  			subprog[cur_subprog].has_tail_call = true;
  		if (BPF_CLASS(code) == BPF_LD &&
  		    (BPF_MODE(code) == BPF_ABS || BPF_MODE(code) == BPF_IND))
  			subprog[cur_subprog].has_ld_abs = true;
  		if (BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32)
  			goto next;
  		if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL)
  			goto next;
  		off = i + insn[i].off + 1;
  		if (off < subprog_start || off >= subprog_end) {
  			verbose(env, "jump out of range from insn %d to %d\n", i, off);
  			return -EINVAL;
  		}
  next:
  		if (i == subprog_end - 1) {
  			/* to avoid fall-through from one subprog into another
  			 * the last insn of the subprog should be either exit
  			 * or unconditional jump back
  			 */
  			if (code != (BPF_JMP | BPF_EXIT) &&
  			    code != (BPF_JMP | BPF_JA)) {
  				verbose(env, "last insn is not an exit or jmp\n");
  				return -EINVAL;
  			}
  			subprog_start = subprog_end;
  			cur_subprog++;
  			if (cur_subprog < env->subprog_cnt)
  				subprog_end = subprog[cur_subprog + 1].start;
  		}
  	}
  	return 0;
  }
  
  /* Parentage chain of this register (or stack slot) should take care of all
   * issues like callee-saved registers, stack slot allocation time, etc.
   */
  static int mark_reg_read(struct bpf_verifier_env *env,
  			 const struct bpf_reg_state *state,
  			 struct bpf_reg_state *parent, u8 flag)
  {
  	bool writes = parent == state->parent; /* Observe write marks */
  	int cnt = 0;
  
  	while (parent) {
  		/* if read wasn't screened by an earlier write ... */
  		if (writes && state->live & REG_LIVE_WRITTEN)
  			break;
  		if (parent->live & REG_LIVE_DONE) {
  			verbose(env, "verifier BUG type %s var_off %lld off %d\n",
  				reg_type_str(env, parent->type),
  				parent->var_off.value, parent->off);
  			return -EFAULT;
  		}
  		/* The first condition is more likely to be true than the
  		 * second, checked it first.
  		 */
  		if ((parent->live & REG_LIVE_READ) == flag ||
  		    parent->live & REG_LIVE_READ64)
  			/* The parentage chain never changes and
  			 * this parent was already marked as LIVE_READ.
  			 * There is no need to keep walking the chain again and
  			 * keep re-marking all parents as LIVE_READ.
  			 * This case happens when the same register is read
  			 * multiple times without writes into it in-between.
  			 * Also, if parent has the stronger REG_LIVE_READ64 set,
  			 * then no need to set the weak REG_LIVE_READ32.
  			 */
  			break;
  		/* ... then we depend on parent's value */
  		parent->live |= flag;
  		/* REG_LIVE_READ64 overrides REG_LIVE_READ32. */
  		if (flag == REG_LIVE_READ64)
  			parent->live &= ~REG_LIVE_READ32;
  		state = parent;
  		parent = state->parent;
  		writes = true;
  		cnt++;
  	}
  
  	if (env->longest_mark_read_walk < cnt)
  		env->longest_mark_read_walk = cnt;
  	return 0;
  }
  
  /* This function is supposed to be used by the following 32-bit optimization
   * code only. It returns TRUE if the source or destination register operates
   * on 64-bit, otherwise return FALSE.
   */
  static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn,
  		     u32 regno, struct bpf_reg_state *reg, enum reg_arg_type t)
  {
  	u8 code, class, op;
  
  	code = insn->code;
  	class = BPF_CLASS(code);
  	op = BPF_OP(code);
  	if (class == BPF_JMP) {
  		/* BPF_EXIT for "main" will reach here. Return TRUE
  		 * conservatively.
  		 */
  		if (op == BPF_EXIT)
  			return true;
  		if (op == BPF_CALL) {
  			/* BPF to BPF call will reach here because of marking
  			 * caller saved clobber with DST_OP_NO_MARK for which we
  			 * don't care the register def because they are anyway
  			 * marked as NOT_INIT already.
  			 */
  			if (insn->src_reg == BPF_PSEUDO_CALL)
  				return false;
  			/* Helper call will reach here because of arg type
  			 * check, conservatively return TRUE.
  			 */
  			if (t == SRC_OP)
  				return true;
  
  			return false;
  		}
  	}
  
  	if (class == BPF_ALU64 || class == BPF_JMP ||
  	    /* BPF_END always use BPF_ALU class. */
  	    (class == BPF_ALU && op == BPF_END && insn->imm == 64))
  		return true;
  
  	if (class == BPF_ALU || class == BPF_JMP32)
  		return false;
  
  	if (class == BPF_LDX) {
  		if (t != SRC_OP)
  			return BPF_SIZE(code) == BPF_DW;
  		/* LDX source must be ptr. */
  		return true;
  	}
  
  	if (class == BPF_STX) {
  		/* BPF_STX (including atomic variants) has multiple source
  		 * operands, one of which is a ptr. Check whether the caller is
  		 * asking about it.
  		 */
  		if (t == SRC_OP && reg->type != SCALAR_VALUE)
  			return true;
  		return BPF_SIZE(code) == BPF_DW;
  	}
  
  	if (class == BPF_LD) {
  		u8 mode = BPF_MODE(code);
  
  		/* LD_IMM64 */
  		if (mode == BPF_IMM)
  			return true;
  
  		/* Both LD_IND and LD_ABS return 32-bit data. */
  		if (t != SRC_OP)
  			return  false;
  
  		/* Implicit ctx ptr. */
  		if (regno == BPF_REG_6)
  			return true;
  
  		/* Explicit source could be any width. */
  		return true;
  	}
  
  	if (class == BPF_ST)
  		/* The only source register for BPF_ST is a ptr. */
  		return true;
  
  	/* Conservatively return true at default. */
  	return true;
  }
  
  /* Return the regno defined by the insn, or -1. */
  static int insn_def_regno(const struct bpf_insn *insn)
  {
  	switch (BPF_CLASS(insn->code)) {
  	case BPF_JMP:
  	case BPF_JMP32:
  	case BPF_ST:
  		return -1;
  	case BPF_STX:
  		if (BPF_MODE(insn->code) == BPF_ATOMIC &&
  		    (insn->imm & BPF_FETCH)) {
  			if (insn->imm == BPF_CMPXCHG)
  				return BPF_REG_0;
  			else
  				return insn->src_reg;
  		} else {
  			return -1;
  		}
  	default:
  		return insn->dst_reg;
  	}
  }
  
  /* Return TRUE if INSN has defined any 32-bit value explicitly. */
  static bool insn_has_def32(struct bpf_verifier_env *env, struct bpf_insn *insn)
  {
  	int dst_reg = insn_def_regno(insn);
  
  	if (dst_reg == -1)
  		return false;
  
  	return !is_reg64(env, insn, dst_reg, NULL, DST_OP);
  }
  
  static void mark_insn_zext(struct bpf_verifier_env *env,
  			   struct bpf_reg_state *reg)
  {
  	s32 def_idx = reg->subreg_def;
  
  	if (def_idx == DEF_NOT_SUBREG)
  		return;
  
  	env->insn_aux_data[def_idx - 1].zext_dst = true;
  	/* The dst will be zero extended, so won't be sub-register anymore. */
  	reg->subreg_def = DEF_NOT_SUBREG;
  }
  
  static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
  			 enum reg_arg_type t)
  {
  	struct bpf_verifier_state *vstate = env->cur_state;
  	struct bpf_func_state *state = vstate->frame[vstate->curframe];
  	struct bpf_insn *insn = env->prog->insnsi + env->insn_idx;
  	struct bpf_reg_state *reg, *regs = state->regs;
  	bool rw64;
  
  	if (regno >= MAX_BPF_REG) {
  		verbose(env, "R%d is invalid\n", regno);
  		return -EINVAL;
  	}
  
  	mark_reg_scratched(env, regno);
  
  	reg = &regs[regno];
  	rw64 = is_reg64(env, insn, regno, reg, t);
  	if (t == SRC_OP) {
  		/* check whether register used as source operand can be read */
  		if (reg->type == NOT_INIT) {
  			verbose(env, "R%d !read_ok\n", regno);
  			return -EACCES;
  		}
  		/* We don't need to worry about FP liveness because it's read-only */
  		if (regno == BPF_REG_FP)
  			return 0;
  
  		if (rw64)
  			mark_insn_zext(env, reg);
  
  		return mark_reg_read(env, reg, reg->parent,
  				     rw64 ? REG_LIVE_READ64 : REG_LIVE_READ32);
  	} else {
  		/* check whether register used as dest operand can be written to */
  		if (regno == BPF_REG_FP) {
  			verbose(env, "frame pointer is read only\n");
  			return -EACCES;
  		}
  		reg->live |= REG_LIVE_WRITTEN;
  		reg->subreg_def = rw64 ? DEF_NOT_SUBREG : env->insn_idx + 1;
  		if (t == DST_OP)
  			mark_reg_unknown(env, regs, regno);
  	}
  	return 0;
  }
  
  /* for any branch, call, exit record the history of jmps in the given state */
  static int push_jmp_history(struct bpf_verifier_env *env,
  			    struct bpf_verifier_state *cur)
  {
  	u32 cnt = cur->jmp_history_cnt;
  	struct bpf_idx_pair *p;
  
  	cnt++;
  	p = krealloc(cur->jmp_history, cnt * sizeof(*p), GFP_USER);
  	if (!p)
  		return -ENOMEM;
  	p[cnt - 1].idx = env->insn_idx;
  	p[cnt - 1].prev_idx = env->prev_insn_idx;
  	cur->jmp_history = p;
  	cur->jmp_history_cnt = cnt;
  	return 0;
  }
  
  /* Backtrack one insn at a time. If idx is not at the top of recorded
   * history then previous instruction came from straight line execution.
   */
  static int get_prev_insn_idx(struct bpf_verifier_state *st, int i,
  			     u32 *history)
  {
  	u32 cnt = *history;
  
  	if (cnt && st->jmp_history[cnt - 1].idx == i) {
  		i = st->jmp_history[cnt - 1].prev_idx;
  		(*history)--;
  	} else {
  		i--;
  	}
  	return i;
  }
  
  static const char *disasm_kfunc_name(void *data, const struct bpf_insn *insn)
  {
  	const struct btf_type *func;
  	struct btf *desc_btf;
  
  	if (insn->src_reg != BPF_PSEUDO_KFUNC_CALL)
  		return NULL;
  
  	desc_btf = find_kfunc_desc_btf(data, insn->imm, insn->off);
  	if (IS_ERR(desc_btf))
  		return "<error>";
  
  	func = btf_type_by_id(desc_btf, insn->imm);
  	return btf_name_by_offset(desc_btf, func->name_off);
  }
  
  /* For given verifier state backtrack_insn() is called from the last insn to
   * the first insn. Its purpose is to compute a bitmask of registers and
   * stack slots that needs precision in the parent verifier state.
   */
  static int backtrack_insn(struct bpf_verifier_env *env, int idx,
  			  u32 *reg_mask, u64 *stack_mask)
  {
  	const struct bpf_insn_cbs cbs = {
  		.cb_call	= disasm_kfunc_name,
  		.cb_print	= verbose,
  		.private_data	= env,
  	};
  	struct bpf_insn *insn = env->prog->insnsi + idx;
  	u8 class = BPF_CLASS(insn->code);
  	u8 opcode = BPF_OP(insn->code);
  	u8 mode = BPF_MODE(insn->code);
  	u32 dreg = 1u << insn->dst_reg;
  	u32 sreg = 1u << insn->src_reg;
  	u32 spi;
  
  	if (insn->code == 0)
  		return 0;
  	if (env->log.level & BPF_LOG_LEVEL2) {
  		verbose(env, "regs=%x stack=%llx before ", *reg_mask, *stack_mask);
  		verbose(env, "%d: ", idx);
  		print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
  	}
  
  	if (class == BPF_ALU || class == BPF_ALU64) {
  		if (!(*reg_mask & dreg))
  			return 0;
  		if (opcode == BPF_MOV) {
  			if (BPF_SRC(insn->code) == BPF_X) {
  				/* dreg = sreg
  				 * dreg needs precision after this insn
  				 * sreg needs precision before this insn
  				 */
  				*reg_mask &= ~dreg;
  				*reg_mask |= sreg;
  			} else {
  				/* dreg = K
  				 * dreg needs precision after this insn.
  				 * Corresponding register is already marked
  				 * as precise=true in this verifier state.
  				 * No further markings in parent are necessary
  				 */
  				*reg_mask &= ~dreg;
  			}
  		} else {
  			if (BPF_SRC(insn->code) == BPF_X) {
  				/* dreg += sreg
  				 * both dreg and sreg need precision
  				 * before this insn
  				 */
  				*reg_mask |= sreg;
  			} /* else dreg += K
  			   * dreg still needs precision before this insn
  			   */
  		}
  	} else if (class == BPF_LDX) {
  		if (!(*reg_mask & dreg))
  			return 0;
  		*reg_mask &= ~dreg;
  
  		/* scalars can only be spilled into stack w/o losing precision.
  		 * Load from any other memory can be zero extended.
  		 * The desire to keep that precision is already indicated
  		 * by 'precise' mark in corresponding register of this state.
  		 * No further tracking necessary.
  		 */
  		if (insn->src_reg != BPF_REG_FP)
  			return 0;
  
  		/* dreg = *(u64 *)[fp - off] was a fill from the stack.
  		 * that [fp - off] slot contains scalar that needs to be
  		 * tracked with precision
  		 */
  		spi = (-insn->off - 1) / BPF_REG_SIZE;
  		if (spi >= 64) {
  			verbose(env, "BUG spi %d\n", spi);
  			WARN_ONCE(1, "verifier backtracking bug");
  			return -EFAULT;
  		}
  		*stack_mask |= 1ull << spi;
  	} else if (class == BPF_STX || class == BPF_ST) {
  		if (*reg_mask & dreg)
  			/* stx & st shouldn't be using _scalar_ dst_reg
  			 * to access memory. It means backtracking
  			 * encountered a case of pointer subtraction.
  			 */
  			return -ENOTSUPP;
  		/* scalars can only be spilled into stack */
  		if (insn->dst_reg != BPF_REG_FP)
  			return 0;
  		spi = (-insn->off - 1) / BPF_REG_SIZE;
  		if (spi >= 64) {
  			verbose(env, "BUG spi %d\n", spi);
  			WARN_ONCE(1, "verifier backtracking bug");
  			return -EFAULT;
  		}
  		if (!(*stack_mask & (1ull << spi)))
  			return 0;
  		*stack_mask &= ~(1ull << spi);
  		if (class == BPF_STX)
  			*reg_mask |= sreg;
  	} else if (class == BPF_JMP || class == BPF_JMP32) {
  		if (opcode == BPF_CALL) {
  			if (insn->src_reg == BPF_PSEUDO_CALL)
  				return -ENOTSUPP;
  			/* regular helper call sets R0 */
  			*reg_mask &= ~1;
  			if (*reg_mask & 0x3f) {
  				/* if backtracing was looking for registers R1-R5
  				 * they should have been found already.
  				 */
  				verbose(env, "BUG regs %x\n", *reg_mask);
  				WARN_ONCE(1, "verifier backtracking bug");
  				return -EFAULT;
  			}
  		} else if (opcode == BPF_EXIT) {
  			return -ENOTSUPP;
  		}
  	} else if (class == BPF_LD) {
  		if (!(*reg_mask & dreg))
  			return 0;
  		*reg_mask &= ~dreg;
  		/* It's ld_imm64 or ld_abs or ld_ind.
  		 * For ld_imm64 no further tracking of precision
  		 * into parent is necessary
  		 */
  		if (mode == BPF_IND || mode == BPF_ABS)
  			/* to be analyzed */
  			return -ENOTSUPP;
  	}
  	return 0;
  }
  
  /* the scalar precision tracking algorithm:
   * . at the start all registers have precise=false.
   * . scalar ranges are tracked as normal through alu and jmp insns.
   * . once precise value of the scalar register is used in:
   *   .  ptr + scalar alu
   *   . if (scalar cond K|scalar)
   *   .  helper_call(.., scalar, ...) where ARG_CONST is expected
   *   backtrack through the verifier states and mark all registers and
   *   stack slots with spilled constants that these scalar regisers
   *   should be precise.
   * . during state pruning two registers (or spilled stack slots)
   *   are equivalent if both are not precise.
   *
   * Note the verifier cannot simply walk register parentage chain,
   * since many different registers and stack slots could have been
   * used to compute single precise scalar.
   *
   * The approach of starting with precise=true for all registers and then
   * backtrack to mark a register as not precise when the verifier detects
   * that program doesn't care about specific value (e.g., when helper
   * takes register as ARG_ANYTHING parameter) is not safe.
   *
   * It's ok to walk single parentage chain of the verifier states.
   * It's possible that this backtracking will go all the way till 1st insn.
   * All other branches will be explored for needing precision later.
   *
   * The backtracking needs to deal with cases like:
   *   R8=map_value(id=0,off=0,ks=4,vs=1952,imm=0) R9_w=map_value(id=0,off=40,ks=4,vs=1952,imm=0)
   * r9 -= r8
   * r5 = r9
   * if r5 > 0x79f goto pc+7
   *    R5_w=inv(id=0,umax_value=1951,var_off=(0x0; 0x7ff))
   * r5 += 1
   * ...
   * call bpf_perf_event_output#25
   *   where .arg5_type = ARG_CONST_SIZE_OR_ZERO
   *
   * and this case:
   * r6 = 1
   * call foo // uses callee's r6 inside to compute r0
   * r0 += r6
   * if r0 == 0 goto
   *
   * to track above reg_mask/stack_mask needs to be independent for each frame.
   *
   * Also if parent's curframe > frame where backtracking started,
   * the verifier need to mark registers in both frames, otherwise callees
   * may incorrectly prune callers. This is similar to
   * commit 7640ead93924 ("bpf: verifier: make sure callees don't prune with caller differences")
   *
   * For now backtracking falls back into conservative marking.
   */
  static void mark_all_scalars_precise(struct bpf_verifier_env *env,
  				     struct bpf_verifier_state *st)
  {
  	struct bpf_func_state *func;
  	struct bpf_reg_state *reg;
  	int i, j;
  
  	/* big hammer: mark all scalars precise in this path.
  	 * pop_stack may still get !precise scalars.
  	 */
  	for (; st; st = st->parent)
  		for (i = 0; i <= st->curframe; i++) {
  			func = st->frame[i];
  			for (j = 0; j < BPF_REG_FP; j++) {
  				reg = &func->regs[j];
  				if (reg->type != SCALAR_VALUE)
  					continue;
  				reg->precise = true;
  			}
  			for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) {
  				if (!is_spilled_reg(&func->stack[j]))
  					continue;
  				reg = &func->stack[j].spilled_ptr;
  				if (reg->type != SCALAR_VALUE)
  					continue;
  				reg->precise = true;
  			}
  		}
  }
  
  static int __mark_chain_precision(struct bpf_verifier_env *env, int regno,
  				  int spi)
  {
  	struct bpf_verifier_state *st = env->cur_state;
  	int first_idx = st->first_insn_idx;
  	int last_idx = env->insn_idx;
  	struct bpf_func_state *func;
  	struct bpf_reg_state *reg;
  	u32 reg_mask = regno >= 0 ? 1u << regno : 0;
  	u64 stack_mask = spi >= 0 ? 1ull << spi : 0;
  	bool skip_first = true;
  	bool new_marks = false;
  	int i, err;
  
  	if (!env->bpf_capable)
  		return 0;
  
  	func = st->frame[st->curframe];
  	if (regno >= 0) {
  		reg = &func->regs[regno];
  		if (reg->type != SCALAR_VALUE) {
  			WARN_ONCE(1, "backtracing misuse");
  			return -EFAULT;
  		}
  		if (!reg->precise)
  			new_marks = true;
  		else
  			reg_mask = 0;
  		reg->precise = true;
  	}
  
  	while (spi >= 0) {
  		if (!is_spilled_reg(&func->stack[spi])) {
  			stack_mask = 0;
  			break;
  		}
  		reg = &func->stack[spi].spilled_ptr;
  		if (reg->type != SCALAR_VALUE) {
  			stack_mask = 0;
  			break;
  		}
  		if (!reg->precise)
  			new_marks = true;
  		else
  			stack_mask = 0;
  		reg->precise = true;
  		break;
  	}
  
  	if (!new_marks)
  		return 0;
  	if (!reg_mask && !stack_mask)
  		return 0;
  	for (;;) {
  		DECLARE_BITMAP(mask, 64);
  		u32 history = st->jmp_history_cnt;
  
  		if (env->log.level & BPF_LOG_LEVEL2)
  			verbose(env, "last_idx %d first_idx %d\n", last_idx, first_idx);
  		for (i = last_idx;;) {
  			if (skip_first) {
  				err = 0;
  				skip_first = false;
  			} else {
  				err = backtrack_insn(env, i, &reg_mask, &stack_mask);
  			}
  			if (err == -ENOTSUPP) {
  				mark_all_scalars_precise(env, st);
  				return 0;
  			} else if (err) {
  				return err;
  			}
  			if (!reg_mask && !stack_mask)
  				/* Found assignment(s) into tracked register in this state.
  				 * Since this state is already marked, just return.
  				 * Nothing to be tracked further in the parent state.
  				 */
  				return 0;
  			if (i == first_idx)
  				break;
  			i = get_prev_insn_idx(st, i, &history);
  			if (i >= env->prog->len) {
  				/* This can happen if backtracking reached insn 0
  				 * and there are still reg_mask or stack_mask
  				 * to backtrack.
  				 * It means the backtracking missed the spot where
  				 * particular register was initialized with a constant.
  				 */
  				verbose(env, "BUG backtracking idx %d\n", i);
  				WARN_ONCE(1, "verifier backtracking bug");
  				return -EFAULT;
  			}
  		}
  		st = st->parent;
  		if (!st)
  			break;
  
  		new_marks = false;
  		func = st->frame[st->curframe];
  		bitmap_from_u64(mask, reg_mask);
  		for_each_set_bit(i, mask, 32) {
  			reg = &func->regs[i];
  			if (reg->type != SCALAR_VALUE) {
  				reg_mask &= ~(1u << i);
  				continue;
  			}
  			if (!reg->precise)
  				new_marks = true;
  			reg->precise = true;
  		}
  
  		bitmap_from_u64(mask, stack_mask);
  		for_each_set_bit(i, mask, 64) {
  			if (i >= func->allocated_stack / BPF_REG_SIZE) {
  				/* the sequence of instructions:
  				 * 2: (bf) r3 = r10
  				 * 3: (7b) *(u64 *)(r3 -8) = r0
  				 * 4: (79) r4 = *(u64 *)(r10 -8)
  				 * doesn't contain jmps. It's backtracked
  				 * as a single block.
  				 * During backtracking insn 3 is not recognized as
  				 * stack access, so at the end of backtracking
  				 * stack slot fp-8 is still marked in stack_mask.
  				 * However the parent state may not have accessed
  				 * fp-8 and it's "unallocated" stack space.
  				 * In such case fallback to conservative.
  				 */
  				mark_all_scalars_precise(env, st);
  				return 0;
  			}
  
  			if (!is_spilled_reg(&func->stack[i])) {
  				stack_mask &= ~(1ull << i);
  				continue;
  			}
  			reg = &func->stack[i].spilled_ptr;
  			if (reg->type != SCALAR_VALUE) {
  				stack_mask &= ~(1ull << i);
  				continue;
  			}
  			if (!reg->precise)
  				new_marks = true;
  			reg->precise = true;
  		}
  		if (env->log.level & BPF_LOG_LEVEL2) {
  			verbose(env, "parent %s regs=%x stack=%llx marks:",
  				new_marks ? "didn't have" : "already had",
  				reg_mask, stack_mask);
  			print_verifier_state(env, func, true);
  		}
  
  		if (!reg_mask && !stack_mask)
  			break;
  		if (!new_marks)
  			break;
  
  		last_idx = st->last_insn_idx;
  		first_idx = st->first_insn_idx;
  	}
  	return 0;
  }
  
  static int mark_chain_precision(struct bpf_verifier_env *env, int regno)
  {
  	return __mark_chain_precision(env, regno, -1);
  }
  
  static int mark_chain_precision_stack(struct bpf_verifier_env *env, int spi)
  {
  	return __mark_chain_precision(env, -1, spi);
  }
  
  static bool is_spillable_regtype(enum bpf_reg_type type)
  {
  	switch (base_type(type)) {
  	case PTR_TO_MAP_VALUE:
  	case PTR_TO_STACK:
  	case PTR_TO_CTX:
  	case PTR_TO_PACKET:
  	case PTR_TO_PACKET_META:
  	case PTR_TO_PACKET_END:
  	case PTR_TO_FLOW_KEYS:
  	case CONST_PTR_TO_MAP:
  	case PTR_TO_SOCKET:
  	case PTR_TO_SOCK_COMMON:
  	case PTR_TO_TCP_SOCK:
  	case PTR_TO_XDP_SOCK:
  	case PTR_TO_BTF_ID:
  	case PTR_TO_BUF:
  	case PTR_TO_MEM:
  	case PTR_TO_FUNC:
  	case PTR_TO_MAP_KEY:
  		return true;
  	default:
  		return false;
  	}
  }
  
  /* Does this register contain a constant zero? */
  static bool register_is_null(struct bpf_reg_state *reg)
  {
  	return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0);
  }
  
  static bool register_is_const(struct bpf_reg_state *reg)
  {
  	return reg->type == SCALAR_VALUE && tnum_is_const(reg->var_off);
  }
  
  static bool __is_scalar_unbounded(struct bpf_reg_state *reg)
  {
  	return tnum_is_unknown(reg->var_off) &&
  	       reg->smin_value == S64_MIN && reg->smax_value == S64_MAX &&
  	       reg->umin_value == 0 && reg->umax_value == U64_MAX &&
  	       reg->s32_min_value == S32_MIN && reg->s32_max_value == S32_MAX &&
  	       reg->u32_min_value == 0 && reg->u32_max_value == U32_MAX;
  }
  
  static bool register_is_bounded(struct bpf_reg_state *reg)
  {
  	return reg->type == SCALAR_VALUE && !__is_scalar_unbounded(reg);
  }
  
  static bool __is_pointer_value(bool allow_ptr_leaks,
  			       const struct bpf_reg_state *reg)
  {
  	if (allow_ptr_leaks)
  		return false;
  
  	return reg->type != SCALAR_VALUE;
  }
  
  static void save_register_state(struct bpf_func_state *state,
  				int spi, struct bpf_reg_state *reg,
  				int size)
  {
  	int i;
  
  	state->stack[spi].spilled_ptr = *reg;
  	if (size == BPF_REG_SIZE)
  		state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
  
  	for (i = BPF_REG_SIZE; i > BPF_REG_SIZE - size; i--)
  		state->stack[spi].slot_type[i - 1] = STACK_SPILL;
  
  	/* size < 8 bytes spill */
  	for (; i; i--)
  		scrub_spilled_slot(&state->stack[spi].slot_type[i - 1]);
  }
  
  /* check_stack_{read,write}_fixed_off functions track spill/fill of registers,
   * stack boundary and alignment are checked in check_mem_access()
   */
  static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
  				       /* stack frame we're writing to */
  				       struct bpf_func_state *state,
  				       int off, int size, int value_regno,
  				       int insn_idx)
  {
  	struct bpf_func_state *cur; /* state of the current function */
  	int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err;
  	u32 dst_reg = env->prog->insnsi[insn_idx].dst_reg;
  	struct bpf_reg_state *reg = NULL;
  
  	err = grow_stack_state(state, round_up(slot + 1, BPF_REG_SIZE));
  	if (err)
  		return err;
  	/* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
  	 * so it's aligned access and [off, off + size) are within stack limits
  	 */
  	if (!env->allow_ptr_leaks &&
  	    state->stack[spi].slot_type[0] == STACK_SPILL &&
  	    size != BPF_REG_SIZE) {
  		verbose(env, "attempt to corrupt spilled pointer on stack\n");
  		return -EACCES;
  	}
  
  	cur = env->cur_state->frame[env->cur_state->curframe];
  	if (value_regno >= 0)
  		reg = &cur->regs[value_regno];
  	if (!env->bypass_spec_v4) {
  		bool sanitize = reg && is_spillable_regtype(reg->type);
  
  		for (i = 0; i < size; i++) {
  			if (state->stack[spi].slot_type[i] == STACK_INVALID) {
  				sanitize = true;
  				break;
  			}
  		}
  
  		if (sanitize)
  			env->insn_aux_data[insn_idx].sanitize_stack_spill = true;
  	}
  
  	mark_stack_slot_scratched(env, spi);
  	if (reg && !(off % BPF_REG_SIZE) && register_is_bounded(reg) &&
  	    !register_is_null(reg) && env->bpf_capable) {
  		if (dst_reg != BPF_REG_FP) {
  			/* The backtracking logic can only recognize explicit
  			 * stack slot address like [fp - 8]. Other spill of
  			 * scalar via different register has to be conservative.
  			 * Backtrack from here and mark all registers as precise
  			 * that contributed into 'reg' being a constant.
  			 */
  			err = mark_chain_precision(env, value_regno);
  			if (err)
  				return err;
  		}
  		save_register_state(state, spi, reg, size);
  	} else if (reg && is_spillable_regtype(reg->type)) {
  		/* register containing pointer is being spilled into stack */
  		if (size != BPF_REG_SIZE) {
  			verbose_linfo(env, insn_idx, "; ");
  			verbose(env, "invalid size of register spill\n");
  			return -EACCES;
  		}
  		if (state != cur && reg->type == PTR_TO_STACK) {
  			verbose(env, "cannot spill pointers to stack into stack frame of the caller\n");
  			return -EINVAL;
  		}
  		save_register_state(state, spi, reg, size);
  	} else {
  		u8 type = STACK_MISC;
  
  		/* regular write of data into stack destroys any spilled ptr */
  		state->stack[spi].spilled_ptr.type = NOT_INIT;
  		/* Mark slots as STACK_MISC if they belonged to spilled ptr. */
  		if (is_spilled_reg(&state->stack[spi]))
  			for (i = 0; i < BPF_REG_SIZE; i++)
  				scrub_spilled_slot(&state->stack[spi].slot_type[i]);
  
  		/* only mark the slot as written if all 8 bytes were written
  		 * otherwise read propagation may incorrectly stop too soon
  		 * when stack slots are partially written.
  		 * This heuristic means that read propagation will be
  		 * conservative, since it will add reg_live_read marks
  		 * to stack slots all the way to first state when programs
  		 * writes+reads less than 8 bytes
  		 */
  		if (size == BPF_REG_SIZE)
  			state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
  
  		/* when we zero initialize stack slots mark them as such */
  		if (reg && register_is_null(reg)) {
  			/* backtracking doesn't work for STACK_ZERO yet. */
  			err = mark_chain_precision(env, value_regno);
  			if (err)
  				return err;
  			type = STACK_ZERO;
  		}
  
  		/* Mark slots affected by this stack write. */
  		for (i = 0; i < size; i++)
  			state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] =
  				type;
  	}
  	return 0;
  }
  
  /* Write the stack: 'stack[ptr_regno + off] = value_regno'. 'ptr_regno' is
   * known to contain a variable offset.
   * This function checks whether the write is permitted and conservatively
   * tracks the effects of the write, considering that each stack slot in the
   * dynamic range is potentially written to.
   *
   * 'off' includes 'regno->off'.
   * 'value_regno' can be -1, meaning that an unknown value is being written to
   * the stack.
   *
   * Spilled pointers in range are not marked as written because we don't know
   * what's going to be actually written. This means that read propagation for
   * future reads cannot be terminated by this write.
   *
   * For privileged programs, uninitialized stack slots are considered
   * initialized by this write (even though we don't know exactly what offsets
   * are going to be written to). The idea is that we don't want the verifier to
   * reject future reads that access slots written to through variable offsets.
   */
  static int check_stack_write_var_off(struct bpf_verifier_env *env,
  				     /* func where register points to */
  				     struct bpf_func_state *state,
  				     int ptr_regno, int off, int size,
  				     int value_regno, int insn_idx)
  {
  	struct bpf_func_state *cur; /* state of the current function */
  	int min_off, max_off;
  	int i, err;
  	struct bpf_reg_state *ptr_reg = NULL, *value_reg = NULL;
  	bool writing_zero = false;
  	/* set if the fact that we're writing a zero is used to let any
  	 * stack slots remain STACK_ZERO
  	 */
  	bool zero_used = false;
  
  	cur = env->cur_state->frame[env->cur_state->curframe];
  	ptr_reg = &cur->regs[ptr_regno];
  	min_off = ptr_reg->smin_value + off;
  	max_off = ptr_reg->smax_value + off + size;
  	if (value_regno >= 0)
  		value_reg = &cur->regs[value_regno];
  	if (value_reg && register_is_null(value_reg))
  		writing_zero = true;
  
  	err = grow_stack_state(state, round_up(-min_off, BPF_REG_SIZE));
  	if (err)
  		return err;
  
  
  	/* Variable offset writes destroy any spilled pointers in range. */
  	for (i = min_off; i < max_off; i++) {
  		u8 new_type, *stype;
  		int slot, spi;
  
  		slot = -i - 1;
  		spi = slot / BPF_REG_SIZE;
  		stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
  		mark_stack_slot_scratched(env, spi);
  
  		if (!env->allow_ptr_leaks
  				&& *stype != NOT_INIT
  				&& *stype != SCALAR_VALUE) {
  			/* Reject the write if there's are spilled pointers in
  			 * range. If we didn't reject here, the ptr status
  			 * would be erased below (even though not all slots are
  			 * actually overwritten), possibly opening the door to
  			 * leaks.
  			 */
  			verbose(env, "spilled ptr in range of var-offset stack write; insn %d, ptr off: %d",
  				insn_idx, i);
  			return -EINVAL;
  		}
  
  		/* Erase all spilled pointers. */
  		state->stack[spi].spilled_ptr.type = NOT_INIT;
  
  		/* Update the slot type. */
  		new_type = STACK_MISC;
  		if (writing_zero && *stype == STACK_ZERO) {
  			new_type = STACK_ZERO;
  			zero_used = true;
  		}
  		/* If the slot is STACK_INVALID, we check whether it's OK to
  		 * pretend that it will be initialized by this write. The slot
  		 * might not actually be written to, and so if we mark it as
  		 * initialized future reads might leak uninitialized memory.
  		 * For privileged programs, we will accept such reads to slots
  		 * that may or may not be written because, if we're reject
  		 * them, the error would be too confusing.
  		 */
  		if (*stype == STACK_INVALID && !env->allow_uninit_stack) {
  			verbose(env, "uninit stack in range of var-offset write prohibited for !root; insn %d, off: %d",
  					insn_idx, i);
  			return -EINVAL;
  		}
  		*stype = new_type;
  	}
  	if (zero_used) {
  		/* backtracking doesn't work for STACK_ZERO yet. */
  		err = mark_chain_precision(env, value_regno);
  		if (err)
  			return err;
  	}
  	return 0;
  }
  
  /* When register 'dst_regno' is assigned some values from stack[min_off,
   * max_off), we set the register's type according to the types of the
   * respective stack slots. If all the stack values are known to be zeros, then
   * so is the destination reg. Otherwise, the register is considered to be
   * SCALAR. This function does not deal with register filling; the caller must
   * ensure that all spilled registers in the stack range have been marked as
   * read.
   */
  static void mark_reg_stack_read(struct bpf_verifier_env *env,
  				/* func where src register points to */
  				struct bpf_func_state *ptr_state,
  				int min_off, int max_off, int dst_regno)
  {
  	struct bpf_verifier_state *vstate = env->cur_state;
  	struct bpf_func_state *state = vstate->frame[vstate->curframe];
  	int i, slot, spi;
  	u8 *stype;
  	int zeros = 0;
  
  	for (i = min_off; i < max_off; i++) {
  		slot = -i - 1;
  		spi = slot / BPF_REG_SIZE;
  		stype = ptr_state->stack[spi].slot_type;
  		if (stype[slot % BPF_REG_SIZE] != STACK_ZERO)
  			break;
  		zeros++;
  	}
  	if (zeros == max_off - min_off) {
  		/* any access_size read into register is zero extended,
  		 * so the whole register == const_zero
  		 */
  		__mark_reg_const_zero(&state->regs[dst_regno]);
  		/* backtracking doesn't support STACK_ZERO yet,
  		 * so mark it precise here, so that later
  		 * backtracking can stop here.
  		 * Backtracking may not need this if this register
  		 * doesn't participate in pointer adjustment.
  		 * Forward propagation of precise flag is not
  		 * necessary either. This mark is only to stop
  		 * backtracking. Any register that contributed
  		 * to const 0 was marked precise before spill.
  		 */
  		state->regs[dst_regno].precise = true;
  	} else {
  		/* have read misc data from the stack */
  		mark_reg_unknown(env, state->regs, dst_regno);
  	}
  	state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
  }
  
  /* Read the stack at 'off' and put the results into the register indicated by
   * 'dst_regno'. It handles reg filling if the addressed stack slot is a
   * spilled reg.
   *
   * 'dst_regno' can be -1, meaning that the read value is not going to a
   * register.
   *
   * The access is assumed to be within the current stack bounds.
   */
  static int check_stack_read_fixed_off(struct bpf_verifier_env *env,
  				      /* func where src register points to */
  				      struct bpf_func_state *reg_state,
  				      int off, int size, int dst_regno)
  {
  	struct bpf_verifier_state *vstate = env->cur_state;
  	struct bpf_func_state *state = vstate->frame[vstate->curframe];
  	int i, slot = -off - 1, spi = slot / BPF_REG_SIZE;
  	struct bpf_reg_state *reg;
  	u8 *stype, type;
  
  	stype = reg_state->stack[spi].slot_type;
  	reg = &reg_state->stack[spi].spilled_ptr;
  
  	if (is_spilled_reg(&reg_state->stack[spi])) {
  		u8 spill_size = 1;
  
  		for (i = BPF_REG_SIZE - 1; i > 0 && stype[i - 1] == STACK_SPILL; i--)
  			spill_size++;
  
  		if (size != BPF_REG_SIZE || spill_size != BPF_REG_SIZE) {
  			if (reg->type != SCALAR_VALUE) {
  				verbose_linfo(env, env->insn_idx, "; ");
  				verbose(env, "invalid size of register fill\n");
  				return -EACCES;
  			}
  
  			mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
  			if (dst_regno < 0)
  				return 0;
  
  			if (!(off % BPF_REG_SIZE) && size == spill_size) {
  				/* The earlier check_reg_arg() has decided the
  				 * subreg_def for this insn.  Save it first.
  				 */
  				s32 subreg_def = state->regs[dst_regno].subreg_def;
  
  				state->regs[dst_regno] = *reg;
  				state->regs[dst_regno].subreg_def = subreg_def;
  			} else {
  				for (i = 0; i < size; i++) {
  					type = stype[(slot - i) % BPF_REG_SIZE];
  					if (type == STACK_SPILL)
  						continue;
  					if (type == STACK_MISC)
  						continue;
  					verbose(env, "invalid read from stack off %d+%d size %d\n",
  						off, i, size);
  					return -EACCES;
  				}
  				mark_reg_unknown(env, state->regs, dst_regno);
  			}
  			state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
  			return 0;
  		}
  
  		if (dst_regno >= 0) {
  			/* restore register state from stack */
  			state->regs[dst_regno] = *reg;
  			/* mark reg as written since spilled pointer state likely
  			 * has its liveness marks cleared by is_state_visited()
  			 * which resets stack/reg liveness for state transitions
  			 */
  			state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
  		} else if (__is_pointer_value(env->allow_ptr_leaks, reg)) {
  			/* If dst_regno==-1, the caller is asking us whether
  			 * it is acceptable to use this value as a SCALAR_VALUE
  			 * (e.g. for XADD).
  			 * We must not allow unprivileged callers to do that
  			 * with spilled pointers.
  			 */
  			verbose(env, "leaking pointer from stack off %d\n",
  				off);
  			return -EACCES;
  		}
  		mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
  	} else {
  		for (i = 0; i < size; i++) {
  			type = stype[(slot - i) % BPF_REG_SIZE];
  			if (type == STACK_MISC)
  				continue;
  			if (type == STACK_ZERO)
  				continue;
  			verbose(env, "invalid read from stack off %d+%d size %d\n",
  				off, i, size);
  			return -EACCES;
  		}
  		mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
  		if (dst_regno >= 0)
  			mark_reg_stack_read(env, reg_state, off, off + size, dst_regno);
  	}
  	return 0;
  }
  
  enum stack_access_src {
  	ACCESS_DIRECT = 1,  /* the access is performed by an instruction */
  	ACCESS_HELPER = 2,  /* the access is performed by a helper */
  };
  
  static int check_stack_range_initialized(struct bpf_verifier_env *env,
  					 int regno, int off, int access_size,
  					 bool zero_size_allowed,
  					 enum stack_access_src type,
  					 struct bpf_call_arg_meta *meta);
  
  static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno)
  {
  	return cur_regs(env) + regno;
  }
  
  /* Read the stack at 'ptr_regno + off' and put the result into the register
   * 'dst_regno'.
   * 'off' includes the pointer register's fixed offset(i.e. 'ptr_regno.off'),
   * but not its variable offset.
   * 'size' is assumed to be <= reg size and the access is assumed to be aligned.
   *
   * As opposed to check_stack_read_fixed_off, this function doesn't deal with
   * filling registers (i.e. reads of spilled register cannot be detected when
   * the offset is not fixed). We conservatively mark 'dst_regno' as containing
   * SCALAR_VALUE. That's why we assert that the 'ptr_regno' has a variable
   * offset; for a fixed offset check_stack_read_fixed_off should be used
   * instead.
   */
  static int check_stack_read_var_off(struct bpf_verifier_env *env,
  				    int ptr_regno, int off, int size, int dst_regno)
  {
  	/* The state of the source register. */
  	struct bpf_reg_state *reg = reg_state(env, ptr_regno);
  	struct bpf_func_state *ptr_state = func(env, reg);
  	int err;
  	int min_off, max_off;
  
  	/* Note that we pass a NULL meta, so raw access will not be permitted.
  	 */
  	err = check_stack_range_initialized(env, ptr_regno, off, size,
  					    false, ACCESS_DIRECT, NULL);
  	if (err)
  		return err;
  
  	min_off = reg->smin_value + off;
  	max_off = reg->smax_value + off;
  	mark_reg_stack_read(env, ptr_state, min_off, max_off + size, dst_regno);
  	return 0;
  }
  
  /* check_stack_read dispatches to check_stack_read_fixed_off or
   * check_stack_read_var_off.
   *
   * The caller must ensure that the offset falls within the allocated stack
   * bounds.
   *
   * 'dst_regno' is a register which will receive the value from the stack. It
   * can be -1, meaning that the read value is not going to a register.
   */
  static int check_stack_read(struct bpf_verifier_env *env,
  			    int ptr_regno, int off, int size,
  			    int dst_regno)
  {
  	struct bpf_reg_state *reg = reg_state(env, ptr_regno);
  	struct bpf_func_state *state = func(env, reg);
  	int err;
  	/* Some accesses are only permitted with a static offset. */
  	bool var_off = !tnum_is_const(reg->var_off);
  
  	/* The offset is required to be static when reads don't go to a
  	 * register, in order to not leak pointers (see
  	 * check_stack_read_fixed_off).
  	 */
  	if (dst_regno < 0 && var_off) {
  		char tn_buf[48];
  
  		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  		verbose(env, "variable offset stack pointer cannot be passed into helper function; var_off=%s off=%d size=%d\n",
  			tn_buf, off, size);
  		return -EACCES;
  	}
  	/* Variable offset is prohibited for unprivileged mode for simplicity
  	 * since it requires corresponding support in Spectre masking for stack
  	 * ALU. See also retrieve_ptr_limit().
  	 */
  	if (!env->bypass_spec_v1 && var_off) {
  		char tn_buf[48];
  
  		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  		verbose(env, "R%d variable offset stack access prohibited for !root, var_off=%s\n",
  				ptr_regno, tn_buf);
  		return -EACCES;
  	}
  
  	if (!var_off) {
  		off += reg->var_off.value;
  		err = check_stack_read_fixed_off(env, state, off, size,
  						 dst_regno);
  	} else {
  		/* Variable offset stack reads need more conservative handling
  		 * than fixed offset ones. Note that dst_regno >= 0 on this
  		 * branch.
  		 */
  		err = check_stack_read_var_off(env, ptr_regno, off, size,
  					       dst_regno);
  	}
  	return err;
  }
  
  
  /* check_stack_write dispatches to check_stack_write_fixed_off or
   * check_stack_write_var_off.
   *
   * 'ptr_regno' is the register used as a pointer into the stack.
   * 'off' includes 'ptr_regno->off', but not its variable offset (if any).
   * 'value_regno' is the register whose value we're writing to the stack. It can
   * be -1, meaning that we're not writing from a register.
   *
   * The caller must ensure that the offset falls within the maximum stack size.
   */
  static int check_stack_write(struct bpf_verifier_env *env,
  			     int ptr_regno, int off, int size,
  			     int value_regno, int insn_idx)
  {
  	struct bpf_reg_state *reg = reg_state(env, ptr_regno);
  	struct bpf_func_state *state = func(env, reg);
  	int err;
  
  	if (tnum_is_const(reg->var_off)) {
  		off += reg->var_off.value;
  		err = check_stack_write_fixed_off(env, state, off, size,
  						  value_regno, insn_idx);
  	} else {
  		/* Variable offset stack reads need more conservative handling
  		 * than fixed offset ones.
  		 */
  		err = check_stack_write_var_off(env, state,
  						ptr_regno, off, size,
  						value_regno, insn_idx);
  	}
  	return err;
  }
  
  static int check_map_access_type(struct bpf_verifier_env *env, u32 regno,
  				 int off, int size, enum bpf_access_type type)
  {
  	struct bpf_reg_state *regs = cur_regs(env);
  	struct bpf_map *map = regs[regno].map_ptr;
  	u32 cap = bpf_map_flags_to_cap(map);
  
  	if (type == BPF_WRITE && !(cap & BPF_MAP_CAN_WRITE)) {
  		verbose(env, "write into map forbidden, value_size=%d off=%d size=%d\n",
  			map->value_size, off, size);
  		return -EACCES;
  	}
  
  	if (type == BPF_READ && !(cap & BPF_MAP_CAN_READ)) {
  		verbose(env, "read from map forbidden, value_size=%d off=%d size=%d\n",
  			map->value_size, off, size);
  		return -EACCES;
  	}
  
  	return 0;
  }
  
  /* check read/write into memory region (e.g., map value, ringbuf sample, etc) */
  static int __check_mem_access(struct bpf_verifier_env *env, int regno,
  			      int off, int size, u32 mem_size,
  			      bool zero_size_allowed)
  {
  	bool size_ok = size > 0 || (size == 0 && zero_size_allowed);
  	struct bpf_reg_state *reg;
  
  	if (off >= 0 && size_ok && (u64)off + size <= mem_size)
  		return 0;
  
  	reg = &cur_regs(env)[regno];
  	switch (reg->type) {
  	case PTR_TO_MAP_KEY:
  		verbose(env, "invalid access to map key, key_size=%d off=%d size=%d\n",
  			mem_size, off, size);
  		break;
  	case PTR_TO_MAP_VALUE:
  		verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n",
  			mem_size, off, size);
  		break;
  	case PTR_TO_PACKET:
  	case PTR_TO_PACKET_META:
  	case PTR_TO_PACKET_END:
  		verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
  			off, size, regno, reg->id, off, mem_size);
  		break;
  	case PTR_TO_MEM:
  	default:
  		verbose(env, "invalid access to memory, mem_size=%u off=%d size=%d\n",
  			mem_size, off, size);
  	}
  
  	return -EACCES;
  }
  
  /* check read/write into a memory region with possible variable offset */
  static int check_mem_region_access(struct bpf_verifier_env *env, u32 regno,
  				   int off, int size, u32 mem_size,
  				   bool zero_size_allowed)
  {
  	struct bpf_verifier_state *vstate = env->cur_state;
  	struct bpf_func_state *state = vstate->frame[vstate->curframe];
  	struct bpf_reg_state *reg = &state->regs[regno];
  	int err;
  
  	/* We may have adjusted the register pointing to memory region, so we
  	 * need to try adding each of min_value and max_value to off
  	 * to make sure our theoretical access will be safe.
  	 *
  	 * The minimum value is only important with signed
  	 * comparisons where we can't assume the floor of a
  	 * value is 0.  If we are using signed variables for our
  	 * index'es we need to make sure that whatever we use
  	 * will have a set floor within our range.
  	 */
  	if (reg->smin_value < 0 &&
  	    (reg->smin_value == S64_MIN ||
  	     (off + reg->smin_value != (s64)(s32)(off + reg->smin_value)) ||
  	      reg->smin_value + off < 0)) {
  		verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
  			regno);
  		return -EACCES;
  	}
  	err = __check_mem_access(env, regno, reg->smin_value + off, size,
  				 mem_size, zero_size_allowed);
  	if (err) {
  		verbose(env, "R%d min value is outside of the allowed memory range\n",
  			regno);
  		return err;
  	}
  
  	/* If we haven't set a max value then we need to bail since we can't be
  	 * sure we won't do bad things.
  	 * If reg->umax_value + off could overflow, treat that as unbounded too.
  	 */
  	if (reg->umax_value >= BPF_MAX_VAR_OFF) {
  		verbose(env, "R%d unbounded memory access, make sure to bounds check any such access\n",
  			regno);
  		return -EACCES;
  	}
  	err = __check_mem_access(env, regno, reg->umax_value + off, size,
  				 mem_size, zero_size_allowed);
  	if (err) {
  		verbose(env, "R%d max value is outside of the allowed memory range\n",
  			regno);
  		return err;
  	}
  
  	return 0;
  }
  
  /* check read/write into a map element with possible variable offset */
  static int check_map_access(struct bpf_verifier_env *env, u32 regno,
  			    int off, int size, bool zero_size_allowed)
  {
  	struct bpf_verifier_state *vstate = env->cur_state;
  	struct bpf_func_state *state = vstate->frame[vstate->curframe];
  	struct bpf_reg_state *reg = &state->regs[regno];
  	struct bpf_map *map = reg->map_ptr;
  	int err;
  
  	err = check_mem_region_access(env, regno, off, size, map->value_size,
  				      zero_size_allowed);
  	if (err)
  		return err;
  
  	if (map_value_has_spin_lock(map)) {
  		u32 lock = map->spin_lock_off;
  
  		/* if any part of struct bpf_spin_lock can be touched by
  		 * load/store reject this program.
  		 * To check that [x1, x2) overlaps with [y1, y2)
  		 * it is sufficient to check x1 < y2 && y1 < x2.
  		 */
  		if (reg->smin_value + off < lock + sizeof(struct bpf_spin_lock) &&
  		     lock < reg->umax_value + off + size) {
  			verbose(env, "bpf_spin_lock cannot be accessed directly by load/store\n");
  			return -EACCES;
  		}
  	}
  	if (map_value_has_timer(map)) {
  		u32 t = map->timer_off;
  
  		if (reg->smin_value + off < t + sizeof(struct bpf_timer) &&
  		     t < reg->umax_value + off + size) {
  			verbose(env, "bpf_timer cannot be accessed directly by load/store\n");
  			return -EACCES;
  		}
  	}
  	return err;
  }
  
  #define MAX_PACKET_OFF 0xffff
  
  static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
  				       const struct bpf_call_arg_meta *meta,
  				       enum bpf_access_type t)
  {
  	enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
  
  	switch (prog_type) {
  	/* Program types only with direct read access go here! */
  	case BPF_PROG_TYPE_LWT_IN:
  	case BPF_PROG_TYPE_LWT_OUT:
  	case BPF_PROG_TYPE_LWT_SEG6LOCAL:
  	case BPF_PROG_TYPE_SK_REUSEPORT:
  	case BPF_PROG_TYPE_FLOW_DISSECTOR:
  	case BPF_PROG_TYPE_CGROUP_SKB:
  		if (t == BPF_WRITE)
  			return false;
  		fallthrough;
  
  	/* Program types with direct read + write access go here! */
  	case BPF_PROG_TYPE_SCHED_CLS:
  	case BPF_PROG_TYPE_SCHED_ACT:
  	case BPF_PROG_TYPE_XDP:
  	case BPF_PROG_TYPE_LWT_XMIT:
  	case BPF_PROG_TYPE_SK_SKB:
  	case BPF_PROG_TYPE_SK_MSG:
  		if (meta)
  			return meta->pkt_access;
  
  		env->seen_direct_write = true;
  		return true;
  
  	case BPF_PROG_TYPE_CGROUP_SOCKOPT:
  		if (t == BPF_WRITE)
  			env->seen_direct_write = true;
  
  		return true;
  
  	default:
  		return false;
  	}
  }
  
  static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
  			       int size, bool zero_size_allowed)
  {
  	struct bpf_reg_state *regs = cur_regs(env);
  	struct bpf_reg_state *reg = &regs[regno];
  	int err;
  
  	/* We may have added a variable offset to the packet pointer; but any
  	 * reg->range we have comes after that.  We are only checking the fixed
  	 * offset.
  	 */
  
  	/* We don't allow negative numbers, because we aren't tracking enough
  	 * detail to prove they're safe.
  	 */
  	if (reg->smin_value < 0) {
  		verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
  			regno);
  		return -EACCES;
  	}
  
  	err = reg->range < 0 ? -EINVAL :
  	      __check_mem_access(env, regno, off, size, reg->range,
  				 zero_size_allowed);
  	if (err) {
  		verbose(env, "R%d offset is outside of the packet\n", regno);
  		return err;
  	}
  
  	/* __check_mem_access has made sure "off + size - 1" is within u16.
  	 * reg->umax_value can't be bigger than MAX_PACKET_OFF which is 0xffff,
  	 * otherwise find_good_pkt_pointers would have refused to set range info
  	 * that __check_mem_access would have rejected this pkt access.
  	 * Therefore, "off + reg->umax_value + size - 1" won't overflow u32.
  	 */
  	env->prog->aux->max_pkt_offset =
  		max_t(u32, env->prog->aux->max_pkt_offset,
  		      off + reg->umax_value + size - 1);
  
  	return err;
  }
  
  /* check access to 'struct bpf_context' fields.  Supports fixed offsets only */
  static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size,
  			    enum bpf_access_type t, enum bpf_reg_type *reg_type,
  			    struct btf **btf, u32 *btf_id)
  {
  	struct bpf_insn_access_aux info = {
  		.reg_type = *reg_type,
  		.log = &env->log,
  	};
  
  	if (env->ops->is_valid_access &&
  	    env->ops->is_valid_access(off, size, t, env->prog, &info)) {
  		/* A non zero info.ctx_field_size indicates that this field is a
  		 * candidate for later verifier transformation to load the whole
  		 * field and then apply a mask when accessed with a narrower
  		 * access than actual ctx access size. A zero info.ctx_field_size
  		 * will only allow for whole field access and rejects any other
  		 * type of narrower access.
  		 */
  		*reg_type = info.reg_type;
  
  		if (base_type(*reg_type) == PTR_TO_BTF_ID) {
  			*btf = info.btf;
  			*btf_id = info.btf_id;
  		} else {
  			env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size;
  		}
  		/* remember the offset of last byte accessed in ctx */
  		if (env->prog->aux->max_ctx_offset < off + size)
  			env->prog->aux->max_ctx_offset = off + size;
  		return 0;
  	}
  
  	verbose(env, "invalid bpf_context access off=%d size=%d\n", off, size);
  	return -EACCES;
  }
  
  static int check_flow_keys_access(struct bpf_verifier_env *env, int off,
  				  int size)
  {
  	if (size < 0 || off < 0 ||
  	    (u64)off + size > sizeof(struct bpf_flow_keys)) {
  		verbose(env, "invalid access to flow keys off=%d size=%d\n",
  			off, size);
  		return -EACCES;
  	}
  	return 0;
  }
  
  static int check_sock_access(struct bpf_verifier_env *env, int insn_idx,
  			     u32 regno, int off, int size,
  			     enum bpf_access_type t)
  {
  	struct bpf_reg_state *regs = cur_regs(env);
  	struct bpf_reg_state *reg = &regs[regno];
  	struct bpf_insn_access_aux info = {};
  	bool valid;
  
  	if (reg->smin_value < 0) {
  		verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
  			regno);
  		return -EACCES;
  	}
  
  	switch (reg->type) {
  	case PTR_TO_SOCK_COMMON:
  		valid = bpf_sock_common_is_valid_access(off, size, t, &info);
  		break;
  	case PTR_TO_SOCKET:
  		valid = bpf_sock_is_valid_access(off, size, t, &info);
  		break;
  	case PTR_TO_TCP_SOCK:
  		valid = bpf_tcp_sock_is_valid_access(off, size, t, &info);
  		break;
  	case PTR_TO_XDP_SOCK:
  		valid = bpf_xdp_sock_is_valid_access(off, size, t, &info);
  		break;
  	default:
  		valid = false;
  	}
  
  
  	if (valid) {
  		env->insn_aux_data[insn_idx].ctx_field_size =
  			info.ctx_field_size;
  		return 0;
  	}
  
  	verbose(env, "R%d invalid %s access off=%d size=%d\n",
  		regno, reg_type_str(env, reg->type), off, size);
  
  	return -EACCES;
  }
  
  static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
  {
  	return __is_pointer_value(env->allow_ptr_leaks, reg_state(env, regno));
  }
  
  static bool is_ctx_reg(struct bpf_verifier_env *env, int regno)
  {
  	const struct bpf_reg_state *reg = reg_state(env, regno);
  
  	return reg->type == PTR_TO_CTX;
  }
  
  static bool is_sk_reg(struct bpf_verifier_env *env, int regno)
  {
  	const struct bpf_reg_state *reg = reg_state(env, regno);
  
  	return type_is_sk_pointer(reg->type);
  }
  
  static bool is_pkt_reg(struct bpf_verifier_env *env, int regno)
  {
  	const struct bpf_reg_state *reg = reg_state(env, regno);
  
  	return type_is_pkt_pointer(reg->type);
  }
  
  static bool is_flow_key_reg(struct bpf_verifier_env *env, int regno)
  {
  	const struct bpf_reg_state *reg = reg_state(env, regno);
  
  	/* Separate to is_ctx_reg() since we still want to allow BPF_ST here. */
  	return reg->type == PTR_TO_FLOW_KEYS;
  }
  
  static int check_pkt_ptr_alignment(struct bpf_verifier_env *env,
  				   const struct bpf_reg_state *reg,
  				   int off, int size, bool strict)
  {
  	struct tnum reg_off;
  	int ip_align;
  
  	/* Byte size accesses are always allowed. */
  	if (!strict || size == 1)
  		return 0;
  
  	/* For platforms that do not have a Kconfig enabling
  	 * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
  	 * NET_IP_ALIGN is universally set to '2'.  And on platforms
  	 * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
  	 * to this code only in strict mode where we want to emulate
  	 * the NET_IP_ALIGN==2 checking.  Therefore use an
  	 * unconditional IP align value of '2'.
  	 */
  	ip_align = 2;
  
  	reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off));
  	if (!tnum_is_aligned(reg_off, size)) {
  		char tn_buf[48];
  
  		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  		verbose(env,
  			"misaligned packet access off %d+%s+%d+%d size %d\n",
  			ip_align, tn_buf, reg->off, off, size);
  		return -EACCES;
  	}
  
  	return 0;
  }
  
  static int check_generic_ptr_alignment(struct bpf_verifier_env *env,
  				       const struct bpf_reg_state *reg,
  				       const char *pointer_desc,
  				       int off, int size, bool strict)
  {
  	struct tnum reg_off;
  
  	/* Byte size accesses are always allowed. */
  	if (!strict || size == 1)
  		return 0;
  
  	reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off));
  	if (!tnum_is_aligned(reg_off, size)) {
  		char tn_buf[48];
  
  		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  		verbose(env, "misaligned %saccess off %s+%d+%d size %d\n",
  			pointer_desc, tn_buf, reg->off, off, size);
  		return -EACCES;
  	}
  
  	return 0;
  }
  
  static int check_ptr_alignment(struct bpf_verifier_env *env,
  			       const struct bpf_reg_state *reg, int off,
  			       int size, bool strict_alignment_once)
  {
  	bool strict = env->strict_alignment || strict_alignment_once;
  	const char *pointer_desc = "";
  
  	switch (reg->type) {
  	case PTR_TO_PACKET:
  	case PTR_TO_PACKET_META:
  		/* Special case, because of NET_IP_ALIGN. Given metadata sits
  		 * right in front, treat it the very same way.
  		 */
  		return check_pkt_ptr_alignment(env, reg, off, size, strict);
  	case PTR_TO_FLOW_KEYS:
  		pointer_desc = "flow keys ";
  		break;
  	case PTR_TO_MAP_KEY:
  		pointer_desc = "key ";
  		break;
  	case PTR_TO_MAP_VALUE:
  		pointer_desc = "value ";
  		break;
  	case PTR_TO_CTX:
  		pointer_desc = "context ";
  		break;
  	case PTR_TO_STACK:
  		pointer_desc = "stack ";
  		/* The stack spill tracking logic in check_stack_write_fixed_off()
  		 * and check_stack_read_fixed_off() relies on stack accesses being
  		 * aligned.
  		 */
  		strict = true;
  		break;
  	case PTR_TO_SOCKET:
  		pointer_desc = "sock ";
  		break;
  	case PTR_TO_SOCK_COMMON:
  		pointer_desc = "sock_common ";
  		break;
  	case PTR_TO_TCP_SOCK:
  		pointer_desc = "tcp_sock ";
  		break;
  	case PTR_TO_XDP_SOCK:
  		pointer_desc = "xdp_sock ";
  		break;
  	default:
  		break;
  	}
  	return check_generic_ptr_alignment(env, reg, pointer_desc, off, size,
  					   strict);
  }
  
  static int update_stack_depth(struct bpf_verifier_env *env,
  			      const struct bpf_func_state *func,
  			      int off)
  {
  	u16 stack = env->subprog_info[func->subprogno].stack_depth;
  
  	if (stack >= -off)
  		return 0;
  
  	/* update known max for given subprogram */
  	env->subprog_info[func->subprogno].stack_depth = -off;
  	return 0;
  }
  
  /* starting from main bpf function walk all instructions of the function
   * and recursively walk all callees that given function can call.
   * Ignore jump and exit insns.
   * Since recursion is prevented by check_cfg() this algorithm
   * only needs a local stack of MAX_CALL_FRAMES to remember callsites
   */
  static int check_max_stack_depth(struct bpf_verifier_env *env)
  {
  	int depth = 0, frame = 0, idx = 0, i = 0, subprog_end;
  	struct bpf_subprog_info *subprog = env->subprog_info;
  	struct bpf_insn *insn = env->prog->insnsi;
  	bool tail_call_reachable = false;
  	int ret_insn[MAX_CALL_FRAMES];
  	int ret_prog[MAX_CALL_FRAMES];
  	int j;
  
  process_func:
  	/* protect against potential stack overflow that might happen when
  	 * bpf2bpf calls get combined with tailcalls. Limit the caller's stack
  	 * depth for such case down to 256 so that the worst case scenario
  	 * would result in 8k stack size (32 which is tailcall limit * 256 =
  	 * 8k).
  	 *
  	 * To get the idea what might happen, see an example:
  	 * func1 -> sub rsp, 128
  	 *  subfunc1 -> sub rsp, 256
  	 *  tailcall1 -> add rsp, 256
  	 *   func2 -> sub rsp, 192 (total stack size = 128 + 192 = 320)
  	 *   subfunc2 -> sub rsp, 64
  	 *   subfunc22 -> sub rsp, 128
  	 *   tailcall2 -> add rsp, 128
  	 *    func3 -> sub rsp, 32 (total stack size 128 + 192 + 64 + 32 = 416)
  	 *
  	 * tailcall will unwind the current stack frame but it will not get rid
  	 * of caller's stack as shown on the example above.
  	 */
  	if (idx && subprog[idx].has_tail_call && depth >= 256) {
  		verbose(env,
  			"tail_calls are not allowed when call stack of previous frames is %d bytes. Too large\n",
  			depth);
  		return -EACCES;
  	}
  	/* round up to 32-bytes, since this is granularity
  	 * of interpreter stack size
  	 */
  	depth += round_up(max_t(u32, subprog[idx].stack_depth, 1), 32);
  	if (depth > MAX_BPF_STACK) {
  		verbose(env, "combined stack size of %d calls is %d. Too large\n",
  			frame + 1, depth);
  		return -EACCES;
  	}
  continue_func:
  	subprog_end = subprog[idx + 1].start;
  	for (; i < subprog_end; i++) {
  		int next_insn;
  
  		if (!bpf_pseudo_call(insn + i) && !bpf_pseudo_func(insn + i))
  			continue;
  		/* remember insn and function to return to */
  		ret_insn[frame] = i + 1;
  		ret_prog[frame] = idx;
  
  		/* find the callee */
  		next_insn = i + insn[i].imm + 1;
  		idx = find_subprog(env, next_insn);
  		if (idx < 0) {
  			WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
  				  next_insn);
  			return -EFAULT;
  		}
  		if (subprog[idx].is_async_cb) {
  			if (subprog[idx].has_tail_call) {
  				verbose(env, "verifier bug. subprog has tail_call and async cb\n");
  				return -EFAULT;
  			}
  			 /* async callbacks don't increase bpf prog stack size */
  			continue;
  		}
  		i = next_insn;
  
  		if (subprog[idx].has_tail_call)
  			tail_call_reachable = true;
  
  		frame++;
  		if (frame >= MAX_CALL_FRAMES) {
  			verbose(env, "the call stack of %d frames is too deep !\n",
  				frame);
  			return -E2BIG;
  		}
  		goto process_func;
  	}
  	/* if tail call got detected across bpf2bpf calls then mark each of the
  	 * currently present subprog frames as tail call reachable subprogs;
  	 * this info will be utilized by JIT so that we will be preserving the
  	 * tail call counter throughout bpf2bpf calls combined with tailcalls
  	 */
  	if (tail_call_reachable)
  		for (j = 0; j < frame; j++)
  			subprog[ret_prog[j]].tail_call_reachable = true;
  	if (subprog[0].tail_call_reachable)
  		env->prog->aux->tail_call_reachable = true;
  
  	/* end of for() loop means the last insn of the 'subprog'
  	 * was reached. Doesn't matter whether it was JA or EXIT
  	 */
  	if (frame == 0)
  		return 0;
  	depth -= round_up(max_t(u32, subprog[idx].stack_depth, 1), 32);
  	frame--;
  	i = ret_insn[frame];
  	idx = ret_prog[frame];
  	goto continue_func;
  }
  
  #ifndef CONFIG_BPF_JIT_ALWAYS_ON
  static int get_callee_stack_depth(struct bpf_verifier_env *env,
  				  const struct bpf_insn *insn, int idx)
  {
  	int start = idx + insn->imm + 1, subprog;
  
  	subprog = find_subprog(env, start);
  	if (subprog < 0) {
  		WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
  			  start);
  		return -EFAULT;
  	}
  	return env->subprog_info[subprog].stack_depth;
  }
  #endif
  
  static int __check_ptr_off_reg(struct bpf_verifier_env *env,
  			       const struct bpf_reg_state *reg, int regno,
  			       bool fixed_off_ok)
  {
  	/* Access to this pointer-typed register or passing it to a helper
  	 * is only allowed in its original, unmodified form.
  	 */
  
  	if (reg->off < 0) {
  		verbose(env, "negative offset %s ptr R%d off=%d disallowed\n",
  			reg_type_str(env, reg->type), regno, reg->off);
  		return -EACCES;
  	}
  
  	if (!fixed_off_ok && reg->off) {
  		verbose(env, "dereference of modified %s ptr R%d off=%d disallowed\n",
  			reg_type_str(env, reg->type), regno, reg->off);
  		return -EACCES;
  	}
  
  	if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
  		char tn_buf[48];
  
  		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  		verbose(env, "variable %s access var_off=%s disallowed\n",
  			reg_type_str(env, reg->type), tn_buf);
  		return -EACCES;
  	}
  
  	return 0;
  }
  
  int check_ptr_off_reg(struct bpf_verifier_env *env,
  		      const struct bpf_reg_state *reg, int regno)
  {
  	return __check_ptr_off_reg(env, reg, regno, false);
  }
  
  static int __check_buffer_access(struct bpf_verifier_env *env,
  				 const char *buf_info,
  				 const struct bpf_reg_state *reg,
  				 int regno, int off, int size)
  {
  	if (off < 0) {
  		verbose(env,
  			"R%d invalid %s buffer access: off=%d, size=%d\n",
  			regno, buf_info, off, size);
  		return -EACCES;
  	}
  	if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
  		char tn_buf[48];
  
  		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  		verbose(env,
  			"R%d invalid variable buffer offset: off=%d, var_off=%s\n",
  			regno, off, tn_buf);
  		return -EACCES;
  	}
  
  	return 0;
  }
  
  static int check_tp_buffer_access(struct bpf_verifier_env *env,
  				  const struct bpf_reg_state *reg,
  				  int regno, int off, int size)
  {
  	int err;
  
  	err = __check_buffer_access(env, "tracepoint", reg, regno, off, size);
  	if (err)
  		return err;
  
  	if (off + size > env->prog->aux->max_tp_access)
  		env->prog->aux->max_tp_access = off + size;
  
  	return 0;
  }
  
  static int check_buffer_access(struct bpf_verifier_env *env,
  			       const struct bpf_reg_state *reg,
  			       int regno, int off, int size,
  			       bool zero_size_allowed,
  			       u32 *max_access)
  {
  	const char *buf_info = type_is_rdonly_mem(reg->type) ? "rdonly" : "rdwr";
  	int err;
  
  	err = __check_buffer_access(env, buf_info, reg, regno, off, size);
  	if (err)
  		return err;
  
  	if (off + size > *max_access)
  		*max_access = off + size;
  
  	return 0;
  }
  
  /* BPF architecture zero extends alu32 ops into 64-bit registesr */
  static void zext_32_to_64(struct bpf_reg_state *reg)
  {
  	reg->var_off = tnum_subreg(reg->var_off);
  	__reg_assign_32_into_64(reg);
  }
  
  /* truncate register to smaller size (in bytes)
   * must be called with size < BPF_REG_SIZE
   */
  static void coerce_reg_to_size(struct bpf_reg_state *reg, int size)
  {
  	u64 mask;
  
  	/* clear high bits in bit representation */
  	reg->var_off = tnum_cast(reg->var_off, size);
  
  	/* fix arithmetic bounds */
  	mask = ((u64)1 << (size * 8)) - 1;
  	if ((reg->umin_value & ~mask) == (reg->umax_value & ~mask)) {
  		reg->umin_value &= mask;
  		reg->umax_value &= mask;
  	} else {
  		reg->umin_value = 0;
  		reg->umax_value = mask;
  	}
  	reg->smin_value = reg->umin_value;
  	reg->smax_value = reg->umax_value;
  
  	/* If size is smaller than 32bit register the 32bit register
  	 * values are also truncated so we push 64-bit bounds into
  	 * 32-bit bounds. Above were truncated < 32-bits already.
  	 */
  	if (size >= 4)
  		return;
  	__reg_combine_64_into_32(reg);
  }
  
  static bool bpf_map_is_rdonly(const struct bpf_map *map)
  {
  	/* A map is considered read-only if the following condition are true:
  	 *
  	 * 1) BPF program side cannot change any of the map content. The
  	 *    BPF_F_RDONLY_PROG flag is throughout the lifetime of a map
  	 *    and was set at map creation time.
  	 * 2) The map value(s) have been initialized from user space by a
  	 *    loader and then "frozen", such that no new map update/delete
  	 *    operations from syscall side are possible for the rest of
  	 *    the map's lifetime from that point onwards.
  	 * 3) Any parallel/pending map update/delete operations from syscall
  	 *    side have been completed. Only after that point, it's safe to
  	 *    assume that map value(s) are immutable.
  	 */
  	return (map->map_flags & BPF_F_RDONLY_PROG) &&
  	       READ_ONCE(map->frozen) &&
  	       !bpf_map_write_active(map);
  }
  
  static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val)
  {
  	void *ptr;
  	u64 addr;
  	int err;
  
  	err = map->ops->map_direct_value_addr(map, &addr, off);
  	if (err)
  		return err;
  	ptr = (void *)(long)addr + off;
  
  	switch (size) {
  	case sizeof(u8):
  		*val = (u64)*(u8 *)ptr;
  		break;
  	case sizeof(u16):
  		*val = (u64)*(u16 *)ptr;
  		break;
  	case sizeof(u32):
  		*val = (u64)*(u32 *)ptr;
  		break;
  	case sizeof(u64):
  		*val = *(u64 *)ptr;
  		break;
  	default:
  		return -EINVAL;
  	}
  	return 0;
  }
  
  static int check_ptr_to_btf_access(struct bpf_verifier_env *env,
  				   struct bpf_reg_state *regs,
  				   int regno, int off, int size,
  				   enum bpf_access_type atype,
  				   int value_regno)
  {
  	struct bpf_reg_state *reg = regs + regno;
  	const struct btf_type *t = btf_type_by_id(reg->btf, reg->btf_id);
  	const char *tname = btf_name_by_offset(reg->btf, t->name_off);
  	enum bpf_type_flag flag = 0;
  	u32 btf_id;
  	int ret;
  
  	if (off < 0) {
  		verbose(env,
  			"R%d is ptr_%s invalid negative access: off=%d\n",
  			regno, tname, off);
  		return -EACCES;
  	}
  	if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
  		char tn_buf[48];
  
  		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  		verbose(env,
  			"R%d is ptr_%s invalid variable offset: off=%d, var_off=%s\n",
  			regno, tname, off, tn_buf);
  		return -EACCES;
  	}
  
  	if (reg->type & MEM_USER) {
  		verbose(env,
  			"R%d is ptr_%s access user memory: off=%d\n",
  			regno, tname, off);
  		return -EACCES;
  	}
  
  	if (reg->type & MEM_PERCPU) {
  		verbose(env,
  			"R%d is ptr_%s access percpu memory: off=%d\n",
  			regno, tname, off);
  		return -EACCES;
  	}
  
  	if (env->ops->btf_struct_access) {
  		ret = env->ops->btf_struct_access(&env->log, reg->btf, t,
  						  off, size, atype, &btf_id, &flag);
  	} else {
  		if (atype != BPF_READ) {
  			verbose(env, "only read is supported\n");
  			return -EACCES;
  		}
  
  		ret = btf_struct_access(&env->log, reg->btf, t, off, size,
  					atype, &btf_id, &flag);
  	}
  
  	if (ret < 0)
  		return ret;
  
  	if (atype == BPF_READ && value_regno >= 0)
  		mark_btf_ld_reg(env, regs, value_regno, ret, reg->btf, btf_id, flag);
  
  	return 0;
  }
  
  static int check_ptr_to_map_access(struct bpf_verifier_env *env,
  				   struct bpf_reg_state *regs,
  				   int regno, int off, int size,
  				   enum bpf_access_type atype,
  				   int value_regno)
  {
  	struct bpf_reg_state *reg = regs + regno;
  	struct bpf_map *map = reg->map_ptr;
  	enum bpf_type_flag flag = 0;
  	const struct btf_type *t;
  	const char *tname;
  	u32 btf_id;
  	int ret;
  
  	if (!btf_vmlinux) {
  		verbose(env, "map_ptr access not supported without CONFIG_DEBUG_INFO_BTF\n");
  		return -ENOTSUPP;
  	}
  
  	if (!map->ops->map_btf_id || !*map->ops->map_btf_id) {
  		verbose(env, "map_ptr access not supported for map type %d\n",
  			map->map_type);
  		return -ENOTSUPP;
  	}
  
  	t = btf_type_by_id(btf_vmlinux, *map->ops->map_btf_id);
  	tname = btf_name_by_offset(btf_vmlinux, t->name_off);
  
  	if (!env->allow_ptr_to_map_access) {
  		verbose(env,
  			"%s access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n",
  			tname);
  		return -EPERM;
  	}
  
  	if (off < 0) {
  		verbose(env, "R%d is %s invalid negative access: off=%d\n",
  			regno, tname, off);
  		return -EACCES;
  	}
  
  	if (atype != BPF_READ) {
  		verbose(env, "only read from %s is supported\n", tname);
  		return -EACCES;
  	}
  
  	ret = btf_struct_access(&env->log, btf_vmlinux, t, off, size, atype, &btf_id, &flag);
  	if (ret < 0)
  		return ret;
  
  	if (value_regno >= 0)
  		mark_btf_ld_reg(env, regs, value_regno, ret, btf_vmlinux, btf_id, flag);
  
  	return 0;
  }
  
  /* Check that the stack access at the given offset is within bounds. The
   * maximum valid offset is -1.
   *
   * The minimum valid offset is -MAX_BPF_STACK for writes, and
   * -state->allocated_stack for reads.
   */
  static int check_stack_slot_within_bounds(int off,
  					  struct bpf_func_state *state,
  					  enum bpf_access_type t)
  {
  	int min_valid_off;
  
  	if (t == BPF_WRITE)
  		min_valid_off = -MAX_BPF_STACK;
  	else
  		min_valid_off = -state->allocated_stack;
  
  	if (off < min_valid_off || off > -1)
  		return -EACCES;
  	return 0;
  }
  
  /* Check that the stack access at 'regno + off' falls within the maximum stack
   * bounds.
   *
   * 'off' includes `regno->offset`, but not its dynamic part (if any).
   */
  static int check_stack_access_within_bounds(
  		struct bpf_verifier_env *env,
  		int regno, int off, int access_size,
  		enum stack_access_src src, enum bpf_access_type type)
  {
  	struct bpf_reg_state *regs = cur_regs(env);
  	struct bpf_reg_state *reg = regs + regno;
  	struct bpf_func_state *state = func(env, reg);
  	int min_off, max_off;
  	int err;
  	char *err_extra;
  
  	if (src == ACCESS_HELPER)
  		/* We don't know if helpers are reading or writing (or both). */
  		err_extra = " indirect access to";
  	else if (type == BPF_READ)
  		err_extra = " read from";
  	else
  		err_extra = " write to";
  
  	if (tnum_is_const(reg->var_off)) {
  		min_off = reg->var_off.value + off;
  		if (access_size > 0)
  			max_off = min_off + access_size - 1;
  		else
  			max_off = min_off;
  	} else {
  		if (reg->smax_value >= BPF_MAX_VAR_OFF ||
  		    reg->smin_value <= -BPF_MAX_VAR_OFF) {
  			verbose(env, "invalid unbounded variable-offset%s stack R%d\n",
  				err_extra, regno);
  			return -EACCES;
  		}
  		min_off = reg->smin_value + off;
  		if (access_size > 0)
  			max_off = reg->smax_value + off + access_size - 1;
  		else
  			max_off = min_off;
  	}
  
  	err = check_stack_slot_within_bounds(min_off, state, type);
  	if (!err)
  		err = check_stack_slot_within_bounds(max_off, state, type);
  
  	if (err) {
  		if (tnum_is_const(reg->var_off)) {
  			verbose(env, "invalid%s stack R%d off=%d size=%d\n",
  				err_extra, regno, off, access_size);
  		} else {
  			char tn_buf[48];
  
  			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  			verbose(env, "invalid variable-offset%s stack R%d var_off=%s size=%d\n",
  				err_extra, regno, tn_buf, access_size);
  		}
  	}
  	return err;
  }
  
  /* check whether memory at (regno + off) is accessible for t = (read | write)
   * if t==write, value_regno is a register which value is stored into memory
   * if t==read, value_regno is a register which will receive the value from memory
   * if t==write && value_regno==-1, some unknown value is stored into memory
   * if t==read && value_regno==-1, don't care what we read from memory
   */
  static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno,
  			    int off, int bpf_size, enum bpf_access_type t,
  			    int value_regno, bool strict_alignment_once)
  {
  	struct bpf_reg_state *regs = cur_regs(env);
  	struct bpf_reg_state *reg = regs + regno;
  	struct bpf_func_state *state;
  	int size, err = 0;
  
  	size = bpf_size_to_bytes(bpf_size);
  	if (size < 0)
  		return size;
  
  	/* alignment checks will add in reg->off themselves */
  	err = check_ptr_alignment(env, reg, off, size, strict_alignment_once);
  	if (err)
  		return err;
  
  	/* for access checks, reg->off is just part of off */
  	off += reg->off;
  
  	if (reg->type == PTR_TO_MAP_KEY) {
  		if (t == BPF_WRITE) {
  			verbose(env, "write to change key R%d not allowed\n", regno);
  			return -EACCES;
  		}
  
  		err = check_mem_region_access(env, regno, off, size,
  					      reg->map_ptr->key_size, false);
  		if (err)
  			return err;
  		if (value_regno >= 0)
  			mark_reg_unknown(env, regs, value_regno);
  	} else if (reg->type == PTR_TO_MAP_VALUE) {
  		if (t == BPF_WRITE && value_regno >= 0 &&
  		    is_pointer_value(env, value_regno)) {
  			verbose(env, "R%d leaks addr into map\n", value_regno);
  			return -EACCES;
  		}
  		err = check_map_access_type(env, regno, off, size, t);
  		if (err)
  			return err;
  		err = check_map_access(env, regno, off, size, false);
  		if (!err && t == BPF_READ && value_regno >= 0) {
  			struct bpf_map *map = reg->map_ptr;
  
  			/* if map is read-only, track its contents as scalars */
  			if (tnum_is_const(reg->var_off) &&
  			    bpf_map_is_rdonly(map) &&
  			    map->ops->map_direct_value_addr) {
  				int map_off = off + reg->var_off.value;
  				u64 val = 0;
  
  				err = bpf_map_direct_read(map, map_off, size,
  							  &val);
  				if (err)
  					return err;
  
  				regs[value_regno].type = SCALAR_VALUE;
  				__mark_reg_known(&regs[value_regno], val);
  			} else {
  				mark_reg_unknown(env, regs, value_regno);
  			}
  		}
  	} else if (base_type(reg->type) == PTR_TO_MEM) {
  		bool rdonly_mem = type_is_rdonly_mem(reg->type);
  
  		if (type_may_be_null(reg->type)) {
  			verbose(env, "R%d invalid mem access '%s'\n", regno,
  				reg_type_str(env, reg->type));
  			return -EACCES;
  		}
  
  		if (t == BPF_WRITE && rdonly_mem) {
  			verbose(env, "R%d cannot write into %s\n",
  				regno, reg_type_str(env, reg->type));
  			return -EACCES;
  		}
  
  		if (t == BPF_WRITE && value_regno >= 0 &&
  		    is_pointer_value(env, value_regno)) {
  			verbose(env, "R%d leaks addr into mem\n", value_regno);
  			return -EACCES;
  		}
  
  		err = check_mem_region_access(env, regno, off, size,
  					      reg->mem_size, false);
  		if (!err && value_regno >= 0 && (t == BPF_READ || rdonly_mem))
  			mark_reg_unknown(env, regs, value_regno);
  	} else if (reg->type == PTR_TO_CTX) {
  		enum bpf_reg_type reg_type = SCALAR_VALUE;
  		struct btf *btf = NULL;
  		u32 btf_id = 0;
  
  		if (t == BPF_WRITE && value_regno >= 0 &&
  		    is_pointer_value(env, value_regno)) {
  			verbose(env, "R%d leaks addr into ctx\n", value_regno);
  			return -EACCES;
  		}
  
  		err = check_ptr_off_reg(env, reg, regno);
  		if (err < 0)
  			return err;
  
  		err = check_ctx_access(env, insn_idx, off, size, t, &reg_type, &btf,
  				       &btf_id);
  		if (err)
  			verbose_linfo(env, insn_idx, "; ");
  		if (!err && t == BPF_READ && value_regno >= 0) {
  			/* ctx access returns either a scalar, or a
  			 * PTR_TO_PACKET[_META,_END]. In the latter
  			 * case, we know the offset is zero.
  			 */
  			if (reg_type == SCALAR_VALUE) {
  				mark_reg_unknown(env, regs, value_regno);
  			} else {
  				mark_reg_known_zero(env, regs,
  						    value_regno);
  				if (type_may_be_null(reg_type))
  					regs[value_regno].id = ++env->id_gen;
  				/* A load of ctx field could have different
  				 * actual load size with the one encoded in the
  				 * insn. When the dst is PTR, it is for sure not
  				 * a sub-register.
  				 */
  				regs[value_regno].subreg_def = DEF_NOT_SUBREG;
  				if (base_type(reg_type) == PTR_TO_BTF_ID) {
  					regs[value_regno].btf = btf;
  					regs[value_regno].btf_id = btf_id;
  				}
  			}
  			regs[value_regno].type = reg_type;
  		}
  
  	} else if (reg->type == PTR_TO_STACK) {
  		/* Basic bounds checks. */
  		err = check_stack_access_within_bounds(env, regno, off, size, ACCESS_DIRECT, t);
  		if (err)
  			return err;
  
  		state = func(env, reg);
  		err = update_stack_depth(env, state, off);
  		if (err)
  			return err;
  
  		if (t == BPF_READ)
  			err = check_stack_read(env, regno, off, size,
  					       value_regno);
  		else
  			err = check_stack_write(env, regno, off, size,
  						value_regno, insn_idx);
  	} else if (reg_is_pkt_pointer(reg)) {
  		if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
  			verbose(env, "cannot write into packet\n");
  			return -EACCES;
  		}
  		if (t == BPF_WRITE && value_regno >= 0 &&
  		    is_pointer_value(env, value_regno)) {
  			verbose(env, "R%d leaks addr into packet\n",
  				value_regno);
  			return -EACCES;
  		}
  		err = check_packet_access(env, regno, off, size, false);
  		if (!err && t == BPF_READ && value_regno >= 0)
  			mark_reg_unknown(env, regs, value_regno);
  	} else if (reg->type == PTR_TO_FLOW_KEYS) {
  		if (t == BPF_WRITE && value_regno >= 0 &&
  		    is_pointer_value(env, value_regno)) {
  			verbose(env, "R%d leaks addr into flow keys\n",
  				value_regno);
  			return -EACCES;
  		}
  
  		err = check_flow_keys_access(env, off, size);
  		if (!err && t == BPF_READ && value_regno >= 0)
  			mark_reg_unknown(env, regs, value_regno);
  	} else if (type_is_sk_pointer(reg->type)) {
  		if (t == BPF_WRITE) {
  			verbose(env, "R%d cannot write into %s\n",
  				regno, reg_type_str(env, reg->type));
  			return -EACCES;
  		}
  		err = check_sock_access(env, insn_idx, regno, off, size, t);
  		if (!err && value_regno >= 0)
  			mark_reg_unknown(env, regs, value_regno);
  	} else if (reg->type == PTR_TO_TP_BUFFER) {
  		err = check_tp_buffer_access(env, reg, regno, off, size);
  		if (!err && t == BPF_READ && value_regno >= 0)
  			mark_reg_unknown(env, regs, value_regno);
  	} else if (base_type(reg->type) == PTR_TO_BTF_ID &&
  		   !type_may_be_null(reg->type)) {
  		err = check_ptr_to_btf_access(env, regs, regno, off, size, t,
  					      value_regno);
  	} else if (reg->type == CONST_PTR_TO_MAP) {
  		err = check_ptr_to_map_access(env, regs, regno, off, size, t,
  					      value_regno);
  	} else if (base_type(reg->type) == PTR_TO_BUF) {
  		bool rdonly_mem = type_is_rdonly_mem(reg->type);
  		u32 *max_access;
  
  		if (rdonly_mem) {
  			if (t == BPF_WRITE) {
  				verbose(env, "R%d cannot write into %s\n",
  					regno, reg_type_str(env, reg->type));
  				return -EACCES;
  			}
  			max_access = &env->prog->aux->max_rdonly_access;
  		} else {
  			max_access = &env->prog->aux->max_rdwr_access;
  		}
  
  		err = check_buffer_access(env, reg, regno, off, size, false,
  					  max_access);
  
  		if (!err && value_regno >= 0 && (rdonly_mem || t == BPF_READ))
  			mark_reg_unknown(env, regs, value_regno);
  	} else {
  		verbose(env, "R%d invalid mem access '%s'\n", regno,
  			reg_type_str(env, reg->type));
  		return -EACCES;
  	}
  
  	if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ &&
  	    regs[value_regno].type == SCALAR_VALUE) {
  		/* b/h/w load zero-extends, mark upper bits as known 0 */
  		coerce_reg_to_size(&regs[value_regno], size);
  	}
  	return err;
  }
  
  static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn)
  {
  	int load_reg;
  	int err;
  
  	switch (insn->imm) {
  	case BPF_ADD:
  	case BPF_ADD | BPF_FETCH:
  	case BPF_AND:
  	case BPF_AND | BPF_FETCH:
  	case BPF_OR:
  	case BPF_OR | BPF_FETCH:
  	case BPF_XOR:
  	case BPF_XOR | BPF_FETCH:
  	case BPF_XCHG:
  	case BPF_CMPXCHG:
  		break;
  	default:
  		verbose(env, "BPF_ATOMIC uses invalid atomic opcode %02x\n", insn->imm);
  		return -EINVAL;
  	}
  
  	if (BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) {
  		verbose(env, "invalid atomic operand size\n");
  		return -EINVAL;
  	}
  
  	/* check src1 operand */
  	err = check_reg_arg(env, insn->src_reg, SRC_OP);
  	if (err)
  		return err;
  
  	/* check src2 operand */
  	err = check_reg_arg(env, insn->dst_reg, SRC_OP);
  	if (err)
  		return err;
  
  	if (insn->imm == BPF_CMPXCHG) {
  		/* Check comparison of R0 with memory location */
  		const u32 aux_reg = BPF_REG_0;
  
  		err = check_reg_arg(env, aux_reg, SRC_OP);
  		if (err)
  			return err;
  
  		if (is_pointer_value(env, aux_reg)) {
  			verbose(env, "R%d leaks addr into mem\n", aux_reg);
  			return -EACCES;
  		}
  	}
  
  	if (is_pointer_value(env, insn->src_reg)) {
  		verbose(env, "R%d leaks addr into mem\n", insn->src_reg);
  		return -EACCES;
  	}
  
  	if (is_ctx_reg(env, insn->dst_reg) ||
  	    is_pkt_reg(env, insn->dst_reg) ||
  	    is_flow_key_reg(env, insn->dst_reg) ||
  	    is_sk_reg(env, insn->dst_reg)) {
  		verbose(env, "BPF_ATOMIC stores into R%d %s is not allowed\n",
  			insn->dst_reg,
  			reg_type_str(env, reg_state(env, insn->dst_reg)->type));
  		return -EACCES;
  	}
  
  	if (insn->imm & BPF_FETCH) {
  		if (insn->imm == BPF_CMPXCHG)
  			load_reg = BPF_REG_0;
  		else
  			load_reg = insn->src_reg;
  
  		/* check and record load of old value */
  		err = check_reg_arg(env, load_reg, DST_OP);
  		if (err)
  			return err;
  	} else {
  		/* This instruction accesses a memory location but doesn't
  		 * actually load it into a register.
  		 */
  		load_reg = -1;
  	}
  
  	/* Check whether we can read the memory, with second call for fetch
  	 * case to simulate the register fill.
  	 */
  	err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
  			       BPF_SIZE(insn->code), BPF_READ, -1, true);
  	if (!err && load_reg >= 0)
  		err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
  				       BPF_SIZE(insn->code), BPF_READ, load_reg,
  				       true);
  	if (err)
  		return err;
  
  	/* Check whether we can write into the same memory. */
  	err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
  			       BPF_SIZE(insn->code), BPF_WRITE, -1, true);
  	if (err)
  		return err;
  
  	return 0;
  }
  
  /* When register 'regno' is used to read the stack (either directly or through
   * a helper function) make sure that it's within stack boundary and, depending
   * on the access type, that all elements of the stack are initialized.
   *
   * 'off' includes 'regno->off', but not its dynamic part (if any).
   *
   * All registers that have been spilled on the stack in the slots within the
   * read offsets are marked as read.
   */
  static int check_stack_range_initialized(
  		struct bpf_verifier_env *env, int regno, int off,
  		int access_size, bool zero_size_allowed,
  		enum stack_access_src type, struct bpf_call_arg_meta *meta)
  {
  	struct bpf_reg_state *reg = reg_state(env, regno);
  	struct bpf_func_state *state = func(env, reg);
  	int err, min_off, max_off, i, j, slot, spi;
  	char *err_extra = type == ACCESS_HELPER ? " indirect" : "";
  	enum bpf_access_type bounds_check_type;
  	/* Some accesses can write anything into the stack, others are
  	 * read-only.
  	 */
  	bool clobber = false;
  
  	if (access_size == 0 && !zero_size_allowed) {
  		verbose(env, "invalid zero-sized read\n");
  		return -EACCES;
  	}
  
  	if (type == ACCESS_HELPER) {
  		/* The bounds checks for writes are more permissive than for
  		 * reads. However, if raw_mode is not set, we'll do extra
  		 * checks below.
  		 */
  		bounds_check_type = BPF_WRITE;
  		clobber = true;
  	} else {
  		bounds_check_type = BPF_READ;
  	}
  	err = check_stack_access_within_bounds(env, regno, off, access_size,
  					       type, bounds_check_type);
  	if (err)
  		return err;
  
  
  	if (tnum_is_const(reg->var_off)) {
  		min_off = max_off = reg->var_off.value + off;
  	} else {
  		/* Variable offset is prohibited for unprivileged mode for
  		 * simplicity since it requires corresponding support in
  		 * Spectre masking for stack ALU.
  		 * See also retrieve_ptr_limit().
  		 */
  		if (!env->bypass_spec_v1) {
  			char tn_buf[48];
  
  			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  			verbose(env, "R%d%s variable offset stack access prohibited for !root, var_off=%s\n",
  				regno, err_extra, tn_buf);
  			return -EACCES;
  		}
  		/* Only initialized buffer on stack is allowed to be accessed
  		 * with variable offset. With uninitialized buffer it's hard to
  		 * guarantee that whole memory is marked as initialized on
  		 * helper return since specific bounds are unknown what may
  		 * cause uninitialized stack leaking.
  		 */
  		if (meta && meta->raw_mode)
  			meta = NULL;
  
  		min_off = reg->smin_value + off;
  		max_off = reg->smax_value + off;
  	}
  
  	if (meta && meta->raw_mode) {
  		meta->access_size = access_size;
  		meta->regno = regno;
  		return 0;
  	}
  
  	for (i = min_off; i < max_off + access_size; i++) {
  		u8 *stype;
  
  		slot = -i - 1;
  		spi = slot / BPF_REG_SIZE;
  		if (state->allocated_stack <= slot)
  			goto err;
  		stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
  		if (*stype == STACK_MISC)
  			goto mark;
  		if (*stype == STACK_ZERO) {
  			if (clobber) {
  				/* helper can write anything into the stack */
  				*stype = STACK_MISC;
  			}
  			goto mark;
  		}
  
  		if (is_spilled_reg(&state->stack[spi]) &&
  		    base_type(state->stack[spi].spilled_ptr.type) == PTR_TO_BTF_ID)
  			goto mark;
  
  		if (is_spilled_reg(&state->stack[spi]) &&
  		    (state->stack[spi].spilled_ptr.type == SCALAR_VALUE ||
  		     env->allow_ptr_leaks)) {
  			if (clobber) {
  				__mark_reg_unknown(env, &state->stack[spi].spilled_ptr);
  				for (j = 0; j < BPF_REG_SIZE; j++)
  					scrub_spilled_slot(&state->stack[spi].slot_type[j]);
  			}
  			goto mark;
  		}
  
  err:
  		if (tnum_is_const(reg->var_off)) {
  			verbose(env, "invalid%s read from stack R%d off %d+%d size %d\n",
  				err_extra, regno, min_off, i - min_off, access_size);
  		} else {
  			char tn_buf[48];
  
  			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  			verbose(env, "invalid%s read from stack R%d var_off %s+%d size %d\n",
  				err_extra, regno, tn_buf, i - min_off, access_size);
  		}
  		return -EACCES;
  mark:
  		/* reading any byte out of 8-byte 'spill_slot' will cause
  		 * the whole slot to be marked as 'read'
  		 */
  		mark_reg_read(env, &state->stack[spi].spilled_ptr,
  			      state->stack[spi].spilled_ptr.parent,
  			      REG_LIVE_READ64);
  	}
  	return update_stack_depth(env, state, min_off);
  }
  
  static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
  				   int access_size, bool zero_size_allowed,
  				   struct bpf_call_arg_meta *meta)
  {
  	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
  	u32 *max_access;
  
  	switch (base_type(reg->type)) {
  	case PTR_TO_PACKET:
  	case PTR_TO_PACKET_META:
  		return check_packet_access(env, regno, reg->off, access_size,
  					   zero_size_allowed);
  	case PTR_TO_MAP_KEY:
  		return check_mem_region_access(env, regno, reg->off, access_size,
  					       reg->map_ptr->key_size, false);
  	case PTR_TO_MAP_VALUE:
  		if (check_map_access_type(env, regno, reg->off, access_size,
  					  meta && meta->raw_mode ? BPF_WRITE :
  					  BPF_READ))
  			return -EACCES;
  		return check_map_access(env, regno, reg->off, access_size,
  					zero_size_allowed);
  	case PTR_TO_MEM:
  		return check_mem_region_access(env, regno, reg->off,
  					       access_size, reg->mem_size,
  					       zero_size_allowed);
  	case PTR_TO_BUF:
  		if (type_is_rdonly_mem(reg->type)) {
  			if (meta && meta->raw_mode)
  				return -EACCES;
  
  			max_access = &env->prog->aux->max_rdonly_access;
  		} else {
  			max_access = &env->prog->aux->max_rdwr_access;
  		}
  		return check_buffer_access(env, reg, regno, reg->off,
  					   access_size, zero_size_allowed,
  					   max_access);
  	case PTR_TO_STACK:
  		return check_stack_range_initialized(
  				env,
  				regno, reg->off, access_size,
  				zero_size_allowed, ACCESS_HELPER, meta);
  	default: /* scalar_value or invalid ptr */
  		/* Allow zero-byte read from NULL, regardless of pointer type */
  		if (zero_size_allowed && access_size == 0 &&
  		    register_is_null(reg))
  			return 0;
  
  		verbose(env, "R%d type=%s ", regno,
  			reg_type_str(env, reg->type));
  		verbose(env, "expected=%s\n", reg_type_str(env, PTR_TO_STACK));
  		return -EACCES;
  	}
  }
  
  static int check_mem_size_reg(struct bpf_verifier_env *env,
  			      struct bpf_reg_state *reg, u32 regno,
  			      bool zero_size_allowed,
  			      struct bpf_call_arg_meta *meta)
  {
  	int err;
  
  	/* This is used to refine r0 return value bounds for helpers
  	 * that enforce this value as an upper bound on return values.
  	 * See do_refine_retval_range() for helpers that can refine
  	 * the return value. C type of helper is u32 so we pull register
  	 * bound from umax_value however, if negative verifier errors
  	 * out. Only upper bounds can be learned because retval is an
  	 * int type and negative retvals are allowed.
  	 */
  	if (meta)
  		meta->msize_max_value = reg->umax_value;
  
  	/* The register is SCALAR_VALUE; the access check
  	 * happens using its boundaries.
  	 */
  	if (!tnum_is_const(reg->var_off))
  		/* For unprivileged variable accesses, disable raw
  		 * mode so that the program is required to
  		 * initialize all the memory that the helper could
  		 * just partially fill up.
  		 */
  		meta = NULL;
  
  	if (reg->smin_value < 0) {
  		verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n",
  			regno);
  		return -EACCES;
  	}
  
  	if (reg->umin_value == 0) {
  		err = check_helper_mem_access(env, regno - 1, 0,
  					      zero_size_allowed,
  					      meta);
  		if (err)
  			return err;
  	}
  
  	if (reg->umax_value >= BPF_MAX_VAR_SIZ) {
  		verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
  			regno);
  		return -EACCES;
  	}
  	err = check_helper_mem_access(env, regno - 1,
  				      reg->umax_value,
  				      zero_size_allowed, meta);
  	if (!err)
  		err = mark_chain_precision(env, regno);
  	return err;
  }
  
  int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
  		   u32 regno, u32 mem_size)
  {
  	if (register_is_null(reg))
  		return 0;
  
  	if (type_may_be_null(reg->type)) {
  		/* Assuming that the register contains a value check if the memory
  		 * access is safe. Temporarily save and restore the register's state as
  		 * the conversion shouldn't be visible to a caller.
  		 */
  		const struct bpf_reg_state saved_reg = *reg;
  		int rv;
  
  		mark_ptr_not_null_reg(reg);
  		rv = check_helper_mem_access(env, regno, mem_size, true, NULL);
  		*reg = saved_reg;
  		return rv;
  	}
  
  	return check_helper_mem_access(env, regno, mem_size, true, NULL);
  }
  
  int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
  			     u32 regno)
  {
  	struct bpf_reg_state *mem_reg = &cur_regs(env)[regno - 1];
  	bool may_be_null = type_may_be_null(mem_reg->type);
  	struct bpf_reg_state saved_reg;
  	int err;
  
  	WARN_ON_ONCE(regno < BPF_REG_2 || regno > BPF_REG_5);
  
  	if (may_be_null) {
  		saved_reg = *mem_reg;
  		mark_ptr_not_null_reg(mem_reg);
  	}
  
  	err = check_mem_size_reg(env, reg, regno, true, NULL);
  
  	if (may_be_null)
  		*mem_reg = saved_reg;
  	return err;
  }
  
  /* Implementation details:
   * bpf_map_lookup returns PTR_TO_MAP_VALUE_OR_NULL
   * Two bpf_map_lookups (even with the same key) will have different reg->id.
   * For traditional PTR_TO_MAP_VALUE the verifier clears reg->id after
   * value_or_null->value transition, since the verifier only cares about
   * the range of access to valid map value pointer and doesn't care about actual
   * address of the map element.
   * For maps with 'struct bpf_spin_lock' inside map value the verifier keeps
   * reg->id > 0 after value_or_null->value transition. By doing so
   * two bpf_map_lookups will be considered two different pointers that
   * point to different bpf_spin_locks.
   * The verifier allows taking only one bpf_spin_lock at a time to avoid
   * dead-locks.
   * Since only one bpf_spin_lock is allowed the checks are simpler than
   * reg_is_refcounted() logic. The verifier needs to remember only
   * one spin_lock instead of array of acquired_refs.
   * cur_state->active_spin_lock remembers which map value element got locked
   * and clears it after bpf_spin_unlock.
   */
  static int process_spin_lock(struct bpf_verifier_env *env, int regno,
  			     bool is_lock)
  {
  	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
  	struct bpf_verifier_state *cur = env->cur_state;
  	bool is_const = tnum_is_const(reg->var_off);
  	struct bpf_map *map = reg->map_ptr;
  	u64 val = reg->var_off.value;
  
  	if (!is_const) {
  		verbose(env,
  			"R%d doesn't have constant offset. bpf_spin_lock has to be at the constant offset\n",
  			regno);
  		return -EINVAL;
  	}
  	if (!map->btf) {
  		verbose(env,
  			"map '%s' has to have BTF in order to use bpf_spin_lock\n",
  			map->name);
  		return -EINVAL;
  	}
  	if (!map_value_has_spin_lock(map)) {
  		if (map->spin_lock_off == -E2BIG)
  			verbose(env,
  				"map '%s' has more than one 'struct bpf_spin_lock'\n",
  				map->name);
  		else if (map->spin_lock_off == -ENOENT)
  			verbose(env,
  				"map '%s' doesn't have 'struct bpf_spin_lock'\n",
  				map->name);
  		else
  			verbose(env,
  				"map '%s' is not a struct type or bpf_spin_lock is mangled\n",
  				map->name);
  		return -EINVAL;
  	}
  	if (map->spin_lock_off != val + reg->off) {
  		verbose(env, "off %lld doesn't point to 'struct bpf_spin_lock'\n",
  			val + reg->off);
  		return -EINVAL;
  	}
  	if (is_lock) {
  		if (cur->active_spin_lock) {
  			verbose(env,
  				"Locking two bpf_spin_locks are not allowed\n");
  			return -EINVAL;
  		}
  		cur->active_spin_lock = reg->id;
  	} else {
  		if (!cur->active_spin_lock) {
  			verbose(env, "bpf_spin_unlock without taking a lock\n");
  			return -EINVAL;
  		}
  		if (cur->active_spin_lock != reg->id) {
  			verbose(env, "bpf_spin_unlock of different lock\n");
  			return -EINVAL;
  		}
  		cur->active_spin_lock = 0;
  	}
  	return 0;
  }
  
  static int process_timer_func(struct bpf_verifier_env *env, int regno,
  			      struct bpf_call_arg_meta *meta)
  {
  	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
  	bool is_const = tnum_is_const(reg->var_off);
  	struct bpf_map *map = reg->map_ptr;
  	u64 val = reg->var_off.value;
  
  	if (!is_const) {
  		verbose(env,
  			"R%d doesn't have constant offset. bpf_timer has to be at the constant offset\n",
  			regno);
  		return -EINVAL;
  	}
  	if (!map->btf) {
  		verbose(env, "map '%s' has to have BTF in order to use bpf_timer\n",
  			map->name);
  		return -EINVAL;
  	}
  	if (!map_value_has_timer(map)) {
  		if (map->timer_off == -E2BIG)
  			verbose(env,
  				"map '%s' has more than one 'struct bpf_timer'\n",
  				map->name);
  		else if (map->timer_off == -ENOENT)
  			verbose(env,
  				"map '%s' doesn't have 'struct bpf_timer'\n",
  				map->name);
  		else
  			verbose(env,
  				"map '%s' is not a struct type or bpf_timer is mangled\n",
  				map->name);
  		return -EINVAL;
  	}
  	if (map->timer_off != val + reg->off) {
  		verbose(env, "off %lld doesn't point to 'struct bpf_timer' that is at %d\n",
  			val + reg->off, map->timer_off);
  		return -EINVAL;
  	}
  	if (meta->map_ptr) {
  		verbose(env, "verifier bug. Two map pointers in a timer helper\n");
  		return -EFAULT;
  	}
  	meta->map_uid = reg->map_uid;
  	meta->map_ptr = map;
  	return 0;
  }
  
  static bool arg_type_is_mem_ptr(enum bpf_arg_type type)
  {
  	return base_type(type) == ARG_PTR_TO_MEM ||
  	       base_type(type) == ARG_PTR_TO_UNINIT_MEM;
  }
  
  static bool arg_type_is_mem_size(enum bpf_arg_type type)
  {
  	return type == ARG_CONST_SIZE ||
  	       type == ARG_CONST_SIZE_OR_ZERO;
  }
  
  static bool arg_type_is_alloc_size(enum bpf_arg_type type)
  {
  	return type == ARG_CONST_ALLOC_SIZE_OR_ZERO;
  }
  
  static bool arg_type_is_int_ptr(enum bpf_arg_type type)
  {
  	return type == ARG_PTR_TO_INT ||
  	       type == ARG_PTR_TO_LONG;
  }
  
  static int int_ptr_type_to_size(enum bpf_arg_type type)
  {
  	if (type == ARG_PTR_TO_INT)
  		return sizeof(u32);
  	else if (type == ARG_PTR_TO_LONG)
  		return sizeof(u64);
  
  	return -EINVAL;
  }
  
  static int resolve_map_arg_type(struct bpf_verifier_env *env,
  				 const struct bpf_call_arg_meta *meta,
  				 enum bpf_arg_type *arg_type)
  {
  	if (!meta->map_ptr) {
  		/* kernel subsystem misconfigured verifier */
  		verbose(env, "invalid map_ptr to access map->type\n");
  		return -EACCES;
  	}
  
  	switch (meta->map_ptr->map_type) {
  	case BPF_MAP_TYPE_SOCKMAP:
  	case BPF_MAP_TYPE_SOCKHASH:
  		if (*arg_type == ARG_PTR_TO_MAP_VALUE) {
  			*arg_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON;
  		} else {
  			verbose(env, "invalid arg_type for sockmap/sockhash\n");
  			return -EINVAL;
  		}
  		break;
  	case BPF_MAP_TYPE_BLOOM_FILTER:
  		if (meta->func_id == BPF_FUNC_map_peek_elem)
  			*arg_type = ARG_PTR_TO_MAP_VALUE;
  		break;
  	default:
  		break;
  	}
  	return 0;
  }
  
  struct bpf_reg_types {
  	const enum bpf_reg_type types[10];
  	u32 *btf_id;
  };
  
  static const struct bpf_reg_types map_key_value_types = {
  	.types = {
  		PTR_TO_STACK,
  		PTR_TO_PACKET,
  		PTR_TO_PACKET_META,
  		PTR_TO_MAP_KEY,
  		PTR_TO_MAP_VALUE,
  	},
  };
  
  static const struct bpf_reg_types sock_types = {
  	.types = {
  		PTR_TO_SOCK_COMMON,
  		PTR_TO_SOCKET,
  		PTR_TO_TCP_SOCK,
  		PTR_TO_XDP_SOCK,
  	},
  };
  
  #ifdef CONFIG_NET
  static const struct bpf_reg_types btf_id_sock_common_types = {
  	.types = {
  		PTR_TO_SOCK_COMMON,
  		PTR_TO_SOCKET,
  		PTR_TO_TCP_SOCK,
  		PTR_TO_XDP_SOCK,
  		PTR_TO_BTF_ID,
  	},
  	.btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
  };
  #endif
  
  static const struct bpf_reg_types mem_types = {
  	.types = {
  		PTR_TO_STACK,
  		PTR_TO_PACKET,
  		PTR_TO_PACKET_META,
  		PTR_TO_MAP_KEY,
  		PTR_TO_MAP_VALUE,
  		PTR_TO_MEM,
  		PTR_TO_MEM | MEM_ALLOC,
  		PTR_TO_BUF,
  	},
  };
  
  static const struct bpf_reg_types int_ptr_types = {
  	.types = {
  		PTR_TO_STACK,
  		PTR_TO_PACKET,
  		PTR_TO_PACKET_META,
  		PTR_TO_MAP_KEY,
  		PTR_TO_MAP_VALUE,
  	},
  };
  
  static const struct bpf_reg_types fullsock_types = { .types = { PTR_TO_SOCKET } };
  static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } };
  static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } };
  static const struct bpf_reg_types alloc_mem_types = { .types = { PTR_TO_MEM | MEM_ALLOC } };
  static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } };
  static const struct bpf_reg_types btf_ptr_types = { .types = { PTR_TO_BTF_ID } };
  static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALUE } };
  static const struct bpf_reg_types percpu_btf_ptr_types = { .types = { PTR_TO_BTF_ID | MEM_PERCPU } };
  static const struct bpf_reg_types func_ptr_types = { .types = { PTR_TO_FUNC } };
  static const struct bpf_reg_types stack_ptr_types = { .types = { PTR_TO_STACK } };
  static const struct bpf_reg_types const_str_ptr_types = { .types = { PTR_TO_MAP_VALUE } };
  static const struct bpf_reg_types timer_types = { .types = { PTR_TO_MAP_VALUE } };
  
  static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
  	[ARG_PTR_TO_MAP_KEY]		= &map_key_value_types,
  	[ARG_PTR_TO_MAP_VALUE]		= &map_key_value_types,
  	[ARG_PTR_TO_UNINIT_MAP_VALUE]	= &map_key_value_types,
  	[ARG_CONST_SIZE]		= &scalar_types,
  	[ARG_CONST_SIZE_OR_ZERO]	= &scalar_types,
  	[ARG_CONST_ALLOC_SIZE_OR_ZERO]	= &scalar_types,
  	[ARG_CONST_MAP_PTR]		= &const_map_ptr_types,
  	[ARG_PTR_TO_CTX]		= &context_types,
  	[ARG_PTR_TO_SOCK_COMMON]	= &sock_types,
  #ifdef CONFIG_NET
  	[ARG_PTR_TO_BTF_ID_SOCK_COMMON]	= &btf_id_sock_common_types,
  #endif
  	[ARG_PTR_TO_SOCKET]		= &fullsock_types,
  	[ARG_PTR_TO_BTF_ID]		= &btf_ptr_types,
  	[ARG_PTR_TO_SPIN_LOCK]		= &spin_lock_types,
  	[ARG_PTR_TO_MEM]		= &mem_types,
  	[ARG_PTR_TO_UNINIT_MEM]		= &mem_types,
  	[ARG_PTR_TO_ALLOC_MEM]		= &alloc_mem_types,
  	[ARG_PTR_TO_INT]		= &int_ptr_types,
  	[ARG_PTR_TO_LONG]		= &int_ptr_types,
  	[ARG_PTR_TO_PERCPU_BTF_ID]	= &percpu_btf_ptr_types,
  	[ARG_PTR_TO_FUNC]		= &func_ptr_types,
  	[ARG_PTR_TO_STACK]		= &stack_ptr_types,
  	[ARG_PTR_TO_CONST_STR]		= &const_str_ptr_types,
  	[ARG_PTR_TO_TIMER]		= &timer_types,
  };
  
  static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
  			  enum bpf_arg_type arg_type,
  			  const u32 *arg_btf_id)
  {
  	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
  	enum bpf_reg_type expected, type = reg->type;
  	const struct bpf_reg_types *compatible;
  	int i, j;
  
  	compatible = compatible_reg_types[base_type(arg_type)];
  	if (!compatible) {
  		verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type);
  		return -EFAULT;
  	}
  
  	/* ARG_PTR_TO_MEM + RDONLY is compatible with PTR_TO_MEM and PTR_TO_MEM + RDONLY,
  	 * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM and NOT with PTR_TO_MEM + RDONLY
  	 *
  	 * Same for MAYBE_NULL:
  	 *
  	 * ARG_PTR_TO_MEM + MAYBE_NULL is compatible with PTR_TO_MEM and PTR_TO_MEM + MAYBE_NULL,
  	 * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM but NOT with PTR_TO_MEM + MAYBE_NULL
  	 *
  	 * Therefore we fold these flags depending on the arg_type before comparison.
  	 */
  	if (arg_type & MEM_RDONLY)
  		type &= ~MEM_RDONLY;
  	if (arg_type & PTR_MAYBE_NULL)
  		type &= ~PTR_MAYBE_NULL;
  
  	for (i = 0; i < ARRAY_SIZE(compatible->types); i++) {
  		expected = compatible->types[i];
  		if (expected == NOT_INIT)
  			break;
  
  		if (type == expected)
  			goto found;
  	}
  
  	verbose(env, "R%d type=%s expected=", regno, reg_type_str(env, reg->type));
  	for (j = 0; j + 1 < i; j++)
  		verbose(env, "%s, ", reg_type_str(env, compatible->types[j]));
  	verbose(env, "%s\n", reg_type_str(env, compatible->types[j]));
  	return -EACCES;
  
  found:
  	if (reg->type == PTR_TO_BTF_ID) {
  		if (!arg_btf_id) {
  			if (!compatible->btf_id) {
  				verbose(env, "verifier internal error: missing arg compatible BTF ID\n");
  				return -EFAULT;
  			}
  			arg_btf_id = compatible->btf_id;
  		}
  
  		if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->off,
  					  btf_vmlinux, *arg_btf_id)) {
  			verbose(env, "R%d is of type %s but %s is expected\n",
  				regno, kernel_type_name(reg->btf, reg->btf_id),
  				kernel_type_name(btf_vmlinux, *arg_btf_id));
  			return -EACCES;
  		}
  	}
  
  	return 0;
  }
  
  int check_func_arg_reg_off(struct bpf_verifier_env *env,
  			   const struct bpf_reg_state *reg, int regno,
  			   enum bpf_arg_type arg_type,
  			   bool is_release_func)
  {
  	bool fixed_off_ok = false, release_reg;
  	enum bpf_reg_type type = reg->type;
  
  	switch ((u32)type) {
  	case SCALAR_VALUE:
  	/* Pointer types where reg offset is explicitly allowed: */
  	case PTR_TO_PACKET:
  	case PTR_TO_PACKET_META:
  	case PTR_TO_MAP_KEY:
  	case PTR_TO_MAP_VALUE:
  	case PTR_TO_MEM:
  	case PTR_TO_MEM | MEM_RDONLY:
  	case PTR_TO_MEM | MEM_ALLOC:
  	case PTR_TO_BUF:
  	case PTR_TO_BUF | MEM_RDONLY:
  	case PTR_TO_STACK:
  		/* Some of the argument types nevertheless require a
  		 * zero register offset.
  		 */
  		if (arg_type != ARG_PTR_TO_ALLOC_MEM)
  			return 0;
  		break;
  	/* All the rest must be rejected, except PTR_TO_BTF_ID which allows
  	 * fixed offset.
  	 */
  	case PTR_TO_BTF_ID:
  		/* When referenced PTR_TO_BTF_ID is passed to release function,
  		 * it's fixed offset must be 0. We rely on the property that
  		 * only one referenced register can be passed to BPF helpers and
  		 * kfuncs. In the other cases, fixed offset can be non-zero.
  		 */
  		release_reg = is_release_func && reg->ref_obj_id;
  		if (release_reg && reg->off) {
  			verbose(env, "R%d must have zero offset when passed to release func\n",
  				regno);
  			return -EINVAL;
  		}
  		/* For release_reg == true, fixed_off_ok must be false, but we
  		 * already checked and rejected reg->off != 0 above, so set to
  		 * true to allow fixed offset for all other cases.
  		 */
  		fixed_off_ok = true;
  		break;
  	default:
  		break;
  	}
  	return __check_ptr_off_reg(env, reg, regno, fixed_off_ok);
  }
  
  static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
  			  struct bpf_call_arg_meta *meta,
  			  const struct bpf_func_proto *fn)
  {
  	u32 regno = BPF_REG_1 + arg;
  	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
  	enum bpf_arg_type arg_type = fn->arg_type[arg];
  	enum bpf_reg_type type = reg->type;
  	int err = 0;
  
  	if (arg_type == ARG_DONTCARE)
  		return 0;
  
  	err = check_reg_arg(env, regno, SRC_OP);
  	if (err)
  		return err;
  
  	if (arg_type == ARG_ANYTHING) {
  		if (is_pointer_value(env, regno)) {
  			verbose(env, "R%d leaks addr into helper function\n",
  				regno);
  			return -EACCES;
  		}
  		return 0;
  	}
  
  	if (type_is_pkt_pointer(type) &&
  	    !may_access_direct_pkt_data(env, meta, BPF_READ)) {
  		verbose(env, "helper access to the packet is not allowed\n");
  		return -EACCES;
  	}
  
  	if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE ||
  	    base_type(arg_type) == ARG_PTR_TO_UNINIT_MAP_VALUE) {
  		err = resolve_map_arg_type(env, meta, &arg_type);
  		if (err)
  			return err;
  	}
  
  	if (register_is_null(reg) && type_may_be_null(arg_type))
  		/* A NULL register has a SCALAR_VALUE type, so skip
  		 * type checking.
  		 */
  		goto skip_type_check;
  
  	err = check_reg_type(env, regno, arg_type, fn->arg_btf_id[arg]);
  	if (err)
  		return err;
  
  	err = check_func_arg_reg_off(env, reg, regno, arg_type, is_release_function(meta->func_id));
  	if (err)
  		return err;
  
  skip_type_check:
  	/* check_func_arg_reg_off relies on only one referenced register being
  	 * allowed for BPF helpers.
  	 */
  	if (reg->ref_obj_id) {
  		if (meta->ref_obj_id) {
  			verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n",
  				regno, reg->ref_obj_id,
  				meta->ref_obj_id);
  			return -EFAULT;
  		}
  		meta->ref_obj_id = reg->ref_obj_id;
  	}
  
  	if (arg_type == ARG_CONST_MAP_PTR) {
  		/* bpf_map_xxx(map_ptr) call: remember that map_ptr */
  		if (meta->map_ptr) {
  			/* Use map_uid (which is unique id of inner map) to reject:
  			 * inner_map1 = bpf_map_lookup_elem(outer_map, key1)
  			 * inner_map2 = bpf_map_lookup_elem(outer_map, key2)
  			 * if (inner_map1 && inner_map2) {
  			 *     timer = bpf_map_lookup_elem(inner_map1);
  			 *     if (timer)
  			 *         // mismatch would have been allowed
  			 *         bpf_timer_init(timer, inner_map2);
  			 * }
  			 *
  			 * Comparing map_ptr is enough to distinguish normal and outer maps.
  			 */
  			if (meta->map_ptr != reg->map_ptr ||
  			    meta->map_uid != reg->map_uid) {
  				verbose(env,
  					"timer pointer in R1 map_uid=%d doesn't match map pointer in R2 map_uid=%d\n",
  					meta->map_uid, reg->map_uid);
  				return -EINVAL;
  			}
  		}
  		meta->map_ptr = reg->map_ptr;
  		meta->map_uid = reg->map_uid;
  	} else if (arg_type == ARG_PTR_TO_MAP_KEY) {
  		/* bpf_map_xxx(..., map_ptr, ..., key) call:
  		 * check that [key, key + map->key_size) are within
  		 * stack limits and initialized
  		 */
  		if (!meta->map_ptr) {
  			/* in function declaration map_ptr must come before
  			 * map_key, so that it's verified and known before
  			 * we have to check map_key here. Otherwise it means
  			 * that kernel subsystem misconfigured verifier
  			 */
  			verbose(env, "invalid map_ptr to access map->key\n");
  			return -EACCES;
  		}
  		err = check_helper_mem_access(env, regno,
  					      meta->map_ptr->key_size, false,
  					      NULL);
  	} else if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE ||
  		   base_type(arg_type) == ARG_PTR_TO_UNINIT_MAP_VALUE) {
  		if (type_may_be_null(arg_type) && register_is_null(reg))
  			return 0;
  
  		/* bpf_map_xxx(..., map_ptr, ..., value) call:
  		 * check [value, value + map->value_size) validity
  		 */
  		if (!meta->map_ptr) {
  			/* kernel subsystem misconfigured verifier */
  			verbose(env, "invalid map_ptr to access map->value\n");
  			return -EACCES;
  		}
  		meta->raw_mode = (arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE);
  		err = check_helper_mem_access(env, regno,
  					      meta->map_ptr->value_size, false,
  					      meta);
  	} else if (arg_type == ARG_PTR_TO_PERCPU_BTF_ID) {
  		if (!reg->btf_id) {
  			verbose(env, "Helper has invalid btf_id in R%d\n", regno);
  			return -EACCES;
  		}
  		meta->ret_btf = reg->btf;
  		meta->ret_btf_id = reg->btf_id;
  	} else if (arg_type == ARG_PTR_TO_SPIN_LOCK) {
  		if (meta->func_id == BPF_FUNC_spin_lock) {
  			if (process_spin_lock(env, regno, true))
  				return -EACCES;
  		} else if (meta->func_id == BPF_FUNC_spin_unlock) {
  			if (process_spin_lock(env, regno, false))
  				return -EACCES;
  		} else {
  			verbose(env, "verifier internal error\n");
  			return -EFAULT;
  		}
  	} else if (arg_type == ARG_PTR_TO_TIMER) {
  		if (process_timer_func(env, regno, meta))
  			return -EACCES;
  	} else if (arg_type == ARG_PTR_TO_FUNC) {
  		meta->subprogno = reg->subprogno;
  	} else if (arg_type_is_mem_ptr(arg_type)) {
  		/* The access to this pointer is only checked when we hit the
  		 * next is_mem_size argument below.
  		 */
  		meta->raw_mode = (arg_type == ARG_PTR_TO_UNINIT_MEM);
  	} else if (arg_type_is_mem_size(arg_type)) {
  		bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO);
  
  		err = check_mem_size_reg(env, reg, regno, zero_size_allowed, meta);
  	} else if (arg_type_is_alloc_size(arg_type)) {
  		if (!tnum_is_const(reg->var_off)) {
  			verbose(env, "R%d is not a known constant'\n",
  				regno);
  			return -EACCES;
  		}
  		meta->mem_size = reg->var_off.value;
  	} else if (arg_type_is_int_ptr(arg_type)) {
  		int size = int_ptr_type_to_size(arg_type);
  
  		err = check_helper_mem_access(env, regno, size, false, meta);
  		if (err)
  			return err;
  		err = check_ptr_alignment(env, reg, 0, size, true);
  	} else if (arg_type == ARG_PTR_TO_CONST_STR) {
  		struct bpf_map *map = reg->map_ptr;
  		int map_off;
  		u64 map_addr;
  		char *str_ptr;
  
  		if (!bpf_map_is_rdonly(map)) {
  			verbose(env, "R%d does not point to a readonly map'\n", regno);
  			return -EACCES;
  		}
  
  		if (!tnum_is_const(reg->var_off)) {
  			verbose(env, "R%d is not a constant address'\n", regno);
  			return -EACCES;
  		}
  
  		if (!map->ops->map_direct_value_addr) {
  			verbose(env, "no direct value access support for this map type\n");
  			return -EACCES;
  		}
  
  		err = check_map_access(env, regno, reg->off,
  				       map->value_size - reg->off, false);
  		if (err)
  			return err;
  
  		map_off = reg->off + reg->var_off.value;
  		err = map->ops->map_direct_value_addr(map, &map_addr, map_off);
  		if (err) {
  			verbose(env, "direct value access on string failed\n");
  			return err;
  		}
  
  		str_ptr = (char *)(long)(map_addr);
  		if (!strnchr(str_ptr + map_off, map->value_size - map_off, 0)) {
  			verbose(env, "string is not zero-terminated\n");
  			return -EINVAL;
  		}
  	}
  
  	return err;
  }
  
  static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id)
  {
  	enum bpf_attach_type eatype = env->prog->expected_attach_type;
  	enum bpf_prog_type type = resolve_prog_type(env->prog);
  
  	if (func_id != BPF_FUNC_map_update_elem)
  		return false;
  
  	/* It's not possible to get access to a locked struct sock in these
  	 * contexts, so updating is safe.
  	 */
  	switch (type) {
  	case BPF_PROG_TYPE_TRACING:
  		if (eatype == BPF_TRACE_ITER)
  			return true;
  		break;
  	case BPF_PROG_TYPE_SOCKET_FILTER:
  	case BPF_PROG_TYPE_SCHED_CLS:
  	case BPF_PROG_TYPE_SCHED_ACT:
  	case BPF_PROG_TYPE_XDP:
  	case BPF_PROG_TYPE_SK_REUSEPORT:
  	case BPF_PROG_TYPE_FLOW_DISSECTOR:
  	case BPF_PROG_TYPE_SK_LOOKUP:
  		return true;
  	default:
  		break;
  	}
  
  	verbose(env, "cannot update sockmap in this context\n");
  	return false;
  }
  
  static bool allow_tail_call_in_subprogs(struct bpf_verifier_env *env)
  {
  	return env->prog->jit_requested && IS_ENABLED(CONFIG_X86_64);
  }
  
  static int check_map_func_compatibility(struct bpf_verifier_env *env,
  					struct bpf_map *map, int func_id)
  {
  	if (!map)
  		return 0;
  
  	/* We need a two way check, first is from map perspective ... */
  	switch (map->map_type) {
  	case BPF_MAP_TYPE_PROG_ARRAY:
  		if (func_id != BPF_FUNC_tail_call)
  			goto error;
  		break;
  	case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
  		if (func_id != BPF_FUNC_perf_event_read &&
  		    func_id != BPF_FUNC_perf_event_output &&
  		    func_id != BPF_FUNC_skb_output &&
  		    func_id != BPF_FUNC_perf_event_read_value &&
  		    func_id != BPF_FUNC_xdp_output)
  			goto error;
  		break;
  	case BPF_MAP_TYPE_RINGBUF:
  		if (func_id != BPF_FUNC_ringbuf_output &&
  		    func_id != BPF_FUNC_ringbuf_reserve &&
  		    func_id != BPF_FUNC_ringbuf_query)
  			goto error;
  		break;
  	case BPF_MAP_TYPE_STACK_TRACE:
  		if (func_id != BPF_FUNC_get_stackid)
  			goto error;
  		break;
  	case BPF_MAP_TYPE_CGROUP_ARRAY:
  		if (func_id != BPF_FUNC_skb_under_cgroup &&
  		    func_id != BPF_FUNC_current_task_under_cgroup)
  			goto error;
  		break;
  	case BPF_MAP_TYPE_CGROUP_STORAGE:
  	case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
  		if (func_id != BPF_FUNC_get_local_storage)
  			goto error;
  		break;
  	case BPF_MAP_TYPE_DEVMAP:
  	case BPF_MAP_TYPE_DEVMAP_HASH:
  		if (func_id != BPF_FUNC_redirect_map &&
  		    func_id != BPF_FUNC_map_lookup_elem)
  			goto error;
  		break;
  	/* Restrict bpf side of cpumap and xskmap, open when use-cases
  	 * appear.
  	 */
  	case BPF_MAP_TYPE_CPUMAP:
  		if (func_id != BPF_FUNC_redirect_map)
  			goto error;
  		break;
  	case BPF_MAP_TYPE_XSKMAP:
  		if (func_id != BPF_FUNC_redirect_map &&
  		    func_id != BPF_FUNC_map_lookup_elem)
  			goto error;
  		break;
  	case BPF_MAP_TYPE_ARRAY_OF_MAPS:
  	case BPF_MAP_TYPE_HASH_OF_MAPS:
  		if (func_id != BPF_FUNC_map_lookup_elem)
  			goto error;
  		break;
  	case BPF_MAP_TYPE_SOCKMAP:
  		if (func_id != BPF_FUNC_sk_redirect_map &&
  		    func_id != BPF_FUNC_sock_map_update &&
  		    func_id != BPF_FUNC_map_delete_elem &&
  		    func_id != BPF_FUNC_msg_redirect_map &&
  		    func_id != BPF_FUNC_sk_select_reuseport &&
  		    func_id != BPF_FUNC_map_lookup_elem &&
  		    !may_update_sockmap(env, func_id))
  			goto error;
  		break;
  	case BPF_MAP_TYPE_SOCKHASH:
  		if (func_id != BPF_FUNC_sk_redirect_hash &&
  		    func_id != BPF_FUNC_sock_hash_update &&
  		    func_id != BPF_FUNC_map_delete_elem &&
  		    func_id != BPF_FUNC_msg_redirect_hash &&
  		    func_id != BPF_FUNC_sk_select_reuseport &&
  		    func_id != BPF_FUNC_map_lookup_elem &&
  		    !may_update_sockmap(env, func_id))
  			goto error;
  		break;
  	case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
  		if (func_id != BPF_FUNC_sk_select_reuseport)
  			goto error;
  		break;
  	case BPF_MAP_TYPE_QUEUE:
  	case BPF_MAP_TYPE_STACK:
  		if (func_id != BPF_FUNC_map_peek_elem &&
  		    func_id != BPF_FUNC_map_pop_elem &&
  		    func_id != BPF_FUNC_map_push_elem)
  			goto error;
  		break;
  	case BPF_MAP_TYPE_SK_STORAGE:
  		if (func_id != BPF_FUNC_sk_storage_get &&
  		    func_id != BPF_FUNC_sk_storage_delete)
  			goto error;
  		break;
  	case BPF_MAP_TYPE_INODE_STORAGE:
  		if (func_id != BPF_FUNC_inode_storage_get &&
  		    func_id != BPF_FUNC_inode_storage_delete)
  			goto error;
  		break;
  	case BPF_MAP_TYPE_TASK_STORAGE:
  		if (func_id != BPF_FUNC_task_storage_get &&
  		    func_id != BPF_FUNC_task_storage_delete)
  			goto error;
  		break;
  	case BPF_MAP_TYPE_BLOOM_FILTER:
  		if (func_id != BPF_FUNC_map_peek_elem &&
  		    func_id != BPF_FUNC_map_push_elem)
  			goto error;
  		break;
  	default:
  		break;
  	}
  
  	/* ... and second from the function itself. */
  	switch (func_id) {
  	case BPF_FUNC_tail_call:
  		if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
  			goto error;
  		if (env->subprog_cnt > 1 && !allow_tail_call_in_subprogs(env)) {
  			verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
  			return -EINVAL;
  		}
  		break;
  	case BPF_FUNC_perf_event_read:
  	case BPF_FUNC_perf_event_output:
  	case BPF_FUNC_perf_event_read_value:
  	case BPF_FUNC_skb_output:
  	case BPF_FUNC_xdp_output:
  		if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
  			goto error;
  		break;
  	case BPF_FUNC_ringbuf_output:
  	case BPF_FUNC_ringbuf_reserve:
  	case BPF_FUNC_ringbuf_query:
  		if (map->map_type != BPF_MAP_TYPE_RINGBUF)
  			goto error;
  		break;
  	case BPF_FUNC_get_stackid:
  		if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
  			goto error;
  		break;
  	case BPF_FUNC_current_task_under_cgroup:
  	case BPF_FUNC_skb_under_cgroup:
  		if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
  			goto error;
  		break;
  	case BPF_FUNC_redirect_map:
  		if (map->map_type != BPF_MAP_TYPE_DEVMAP &&
  		    map->map_type != BPF_MAP_TYPE_DEVMAP_HASH &&
  		    map->map_type != BPF_MAP_TYPE_CPUMAP &&
  		    map->map_type != BPF_MAP_TYPE_XSKMAP)
  			goto error;
  		break;
  	case BPF_FUNC_sk_redirect_map:
  	case BPF_FUNC_msg_redirect_map:
  	case BPF_FUNC_sock_map_update:
  		if (map->map_type != BPF_MAP_TYPE_SOCKMAP)
  			goto error;
  		break;
  	case BPF_FUNC_sk_redirect_hash:
  	case BPF_FUNC_msg_redirect_hash:
  	case BPF_FUNC_sock_hash_update:
  		if (map->map_type != BPF_MAP_TYPE_SOCKHASH)
  			goto error;
  		break;
  	case BPF_FUNC_get_local_storage:
  		if (map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE &&
  		    map->map_type != BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
  			goto error;
  		break;
  	case BPF_FUNC_sk_select_reuseport:
  		if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY &&
  		    map->map_type != BPF_MAP_TYPE_SOCKMAP &&
  		    map->map_type != BPF_MAP_TYPE_SOCKHASH)
  			goto error;
  		break;
  	case BPF_FUNC_map_pop_elem:
  		if (map->map_type != BPF_MAP_TYPE_QUEUE &&
  		    map->map_type != BPF_MAP_TYPE_STACK)
  			goto error;
  		break;
  	case BPF_FUNC_map_peek_elem:
  	case BPF_FUNC_map_push_elem:
  		if (map->map_type != BPF_MAP_TYPE_QUEUE &&
  		    map->map_type != BPF_MAP_TYPE_STACK &&
  		    map->map_type != BPF_MAP_TYPE_BLOOM_FILTER)
  			goto error;
  		break;
  	case BPF_FUNC_sk_storage_get:
  	case BPF_FUNC_sk_storage_delete:
  		if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
  			goto error;
  		break;
  	case BPF_FUNC_inode_storage_get:
  	case BPF_FUNC_inode_storage_delete:
  		if (map->map_type != BPF_MAP_TYPE_INODE_STORAGE)
  			goto error;
  		break;
  	case BPF_FUNC_task_storage_get:
  	case BPF_FUNC_task_storage_delete:
  		if (map->map_type != BPF_MAP_TYPE_TASK_STORAGE)
  			goto error;
  		break;
  	default:
  		break;
  	}
  
  	return 0;
  error:
  	verbose(env, "cannot pass map_type %d into func %s#%d\n",
  		map->map_type, func_id_name(func_id), func_id);
  	return -EINVAL;
  }
  
  static bool check_raw_mode_ok(const struct bpf_func_proto *fn)
  {
  	int count = 0;
  
  	if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM)
  		count++;
  	if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM)
  		count++;
  	if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM)
  		count++;
  	if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM)
  		count++;
  	if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM)
  		count++;
  
  	/* We only support one arg being in raw mode at the moment,
  	 * which is sufficient for the helper functions we have
  	 * right now.
  	 */
  	return count <= 1;
  }
  
  static bool check_args_pair_invalid(enum bpf_arg_type arg_curr,
  				    enum bpf_arg_type arg_next)
  {
  	return (arg_type_is_mem_ptr(arg_curr) &&
  	        !arg_type_is_mem_size(arg_next)) ||
  	       (!arg_type_is_mem_ptr(arg_curr) &&
  		arg_type_is_mem_size(arg_next));
  }
  
  static bool check_arg_pair_ok(const struct bpf_func_proto *fn)
  {
  	/* bpf_xxx(..., buf, len) call will access 'len'
  	 * bytes from memory 'buf'. Both arg types need
  	 * to be paired, so make sure there's no buggy
  	 * helper function specification.
  	 */
  	if (arg_type_is_mem_size(fn->arg1_type) ||
  	    arg_type_is_mem_ptr(fn->arg5_type)  ||
  	    check_args_pair_invalid(fn->arg1_type, fn->arg2_type) ||
  	    check_args_pair_invalid(fn->arg2_type, fn->arg3_type) ||
  	    check_args_pair_invalid(fn->arg3_type, fn->arg4_type) ||
  	    check_args_pair_invalid(fn->arg4_type, fn->arg5_type))
  		return false;
  
  	return true;
  }
  
  static bool check_refcount_ok(const struct bpf_func_proto *fn, int func_id)
  {
  	int count = 0;
  
  	if (arg_type_may_be_refcounted(fn->arg1_type))
  		count++;
  	if (arg_type_may_be_refcounted(fn->arg2_type))
  		count++;
  	if (arg_type_may_be_refcounted(fn->arg3_type))
  		count++;
  	if (arg_type_may_be_refcounted(fn->arg4_type))
  		count++;
  	if (arg_type_may_be_refcounted(fn->arg5_type))
  		count++;
  
  	/* A reference acquiring function cannot acquire
  	 * another refcounted ptr.
  	 */
  	if (may_be_acquire_function(func_id) && count)
  		return false;
  
  	/* We only support one arg being unreferenced at the moment,
  	 * which is sufficient for the helper functions we have right now.
  	 */
  	return count <= 1;
  }
  
  static bool check_btf_id_ok(const struct bpf_func_proto *fn)
  {
  	int i;
  
  	for (i = 0; i < ARRAY_SIZE(fn->arg_type); i++) {
  		if (fn->arg_type[i] == ARG_PTR_TO_BTF_ID && !fn->arg_btf_id[i])
  			return false;
  
  		if (fn->arg_type[i] != ARG_PTR_TO_BTF_ID && fn->arg_btf_id[i])
  			return false;
  	}
  
  	return true;
  }
  
  static int check_func_proto(const struct bpf_func_proto *fn, int func_id)
  {
  	return check_raw_mode_ok(fn) &&
  	       check_arg_pair_ok(fn) &&
  	       check_btf_id_ok(fn) &&
  	       check_refcount_ok(fn, func_id) ? 0 : -EINVAL;
  }
  
  /* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
   * are now invalid, so turn them into unknown SCALAR_VALUE.
   */
  static void __clear_all_pkt_pointers(struct bpf_verifier_env *env,
  				     struct bpf_func_state *state)
  {
  	struct bpf_reg_state *regs = state->regs, *reg;
  	int i;
  
  	for (i = 0; i < MAX_BPF_REG; i++)
  		if (reg_is_pkt_pointer_any(&regs[i]))
  			mark_reg_unknown(env, regs, i);
  
  	bpf_for_each_spilled_reg(i, state, reg) {
  		if (!reg)
  			continue;
  		if (reg_is_pkt_pointer_any(reg))
  			__mark_reg_unknown(env, reg);
  	}
  }
  
  static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
  {
  	struct bpf_verifier_state *vstate = env->cur_state;
  	int i;
  
  	for (i = 0; i <= vstate->curframe; i++)
  		__clear_all_pkt_pointers(env, vstate->frame[i]);
  }
  
  enum {
  	AT_PKT_END = -1,
  	BEYOND_PKT_END = -2,
  };
  
  static void mark_pkt_end(struct bpf_verifier_state *vstate, int regn, bool range_open)
  {
  	struct bpf_func_state *state = vstate->frame[vstate->curframe];
  	struct bpf_reg_state *reg = &state->regs[regn];
  
  	if (reg->type != PTR_TO_PACKET)
  		/* PTR_TO_PACKET_META is not supported yet */
  		return;
  
  	/* The 'reg' is pkt > pkt_end or pkt >= pkt_end.
  	 * How far beyond pkt_end it goes is unknown.
  	 * if (!range_open) it's the case of pkt >= pkt_end
  	 * if (range_open) it's the case of pkt > pkt_end
  	 * hence this pointer is at least 1 byte bigger than pkt_end
  	 */
  	if (range_open)
  		reg->range = BEYOND_PKT_END;
  	else
  		reg->range = AT_PKT_END;
  }
  
  static void release_reg_references(struct bpf_verifier_env *env,
  				   struct bpf_func_state *state,
  				   int ref_obj_id)
  {
  	struct bpf_reg_state *regs = state->regs, *reg;
  	int i;
  
  	for (i = 0; i < MAX_BPF_REG; i++)
  		if (regs[i].ref_obj_id == ref_obj_id)
  			mark_reg_unknown(env, regs, i);
  
  	bpf_for_each_spilled_reg(i, state, reg) {
  		if (!reg)
  			continue;
  		if (reg->ref_obj_id == ref_obj_id)
  			__mark_reg_unknown(env, reg);
  	}
  }
  
  /* The pointer with the specified id has released its reference to kernel
   * resources. Identify all copies of the same pointer and clear the reference.
   */
  static int release_reference(struct bpf_verifier_env *env,
  			     int ref_obj_id)
  {
  	struct bpf_verifier_state *vstate = env->cur_state;
  	int err;
  	int i;
  
  	err = release_reference_state(cur_func(env), ref_obj_id);
  	if (err)
  		return err;
  
  	for (i = 0; i <= vstate->curframe; i++)
  		release_reg_references(env, vstate->frame[i], ref_obj_id);
  
  	return 0;
  }
  
  static void clear_caller_saved_regs(struct bpf_verifier_env *env,
  				    struct bpf_reg_state *regs)
  {
  	int i;
  
  	/* after the call registers r0 - r5 were scratched */
  	for (i = 0; i < CALLER_SAVED_REGS; i++) {
  		mark_reg_not_init(env, regs, caller_saved[i]);
  		check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
  	}
  }
  
  typedef int (*set_callee_state_fn)(struct bpf_verifier_env *env,
  				   struct bpf_func_state *caller,
  				   struct bpf_func_state *callee,
  				   int insn_idx);
  
  static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
  			     int *insn_idx, int subprog,
  			     set_callee_state_fn set_callee_state_cb)
  {
  	struct bpf_verifier_state *state = env->cur_state;
  	struct bpf_func_info_aux *func_info_aux;
  	struct bpf_func_state *caller, *callee;
  	int err;
  	bool is_global = false;
  
  	if (state->curframe + 1 >= MAX_CALL_FRAMES) {
  		verbose(env, "the call stack of %d frames is too deep\n",
  			state->curframe + 2);
  		return -E2BIG;
  	}
  
  	caller = state->frame[state->curframe];
  	if (state->frame[state->curframe + 1]) {
  		verbose(env, "verifier bug. Frame %d already allocated\n",
  			state->curframe + 1);
  		return -EFAULT;
  	}
  
  	func_info_aux = env->prog->aux->func_info_aux;
  	if (func_info_aux)
  		is_global = func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL;
  	err = btf_check_subprog_arg_match(env, subprog, caller->regs);
  	if (err == -EFAULT)
  		return err;
  	if (is_global) {
  		if (err) {
  			verbose(env, "Caller passes invalid args into func#%d\n",
  				subprog);
  			return err;
  		} else {
  			if (env->log.level & BPF_LOG_LEVEL)
  				verbose(env,
  					"Func#%d is global and valid. Skipping.\n",
  					subprog);
  			clear_caller_saved_regs(env, caller->regs);
  
  			/* All global functions return a 64-bit SCALAR_VALUE */
  			mark_reg_unknown(env, caller->regs, BPF_REG_0);
  			caller->regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;
  
  			/* continue with next insn after call */
  			return 0;
  		}
  	}
  
  	if (insn->code == (BPF_JMP | BPF_CALL) &&
  	    insn->src_reg == 0 &&
  	    insn->imm == BPF_FUNC_timer_set_callback) {
  		struct bpf_verifier_state *async_cb;
  
  		/* there is no real recursion here. timer callbacks are async */
  		env->subprog_info[subprog].is_async_cb = true;
  		async_cb = push_async_cb(env, env->subprog_info[subprog].start,
  					 *insn_idx, subprog);
  		if (!async_cb)
  			return -EFAULT;
  		callee = async_cb->frame[0];
  		callee->async_entry_cnt = caller->async_entry_cnt + 1;
  
  		/* Convert bpf_timer_set_callback() args into timer callback args */
  		err = set_callee_state_cb(env, caller, callee, *insn_idx);
  		if (err)
  			return err;
  
  		clear_caller_saved_regs(env, caller->regs);
  		mark_reg_unknown(env, caller->regs, BPF_REG_0);
  		caller->regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;
  		/* continue with next insn after call */
  		return 0;
  	}
  
  	callee = kzalloc(sizeof(*callee), GFP_KERNEL);
  	if (!callee)
  		return -ENOMEM;
  	state->frame[state->curframe + 1] = callee;
  
  	/* callee cannot access r0, r6 - r9 for reading and has to write
  	 * into its own stack before reading from it.
  	 * callee can read/write into caller's stack
  	 */
  	init_func_state(env, callee,
  			/* remember the callsite, it will be used by bpf_exit */
  			*insn_idx /* callsite */,
  			state->curframe + 1 /* frameno within this callchain */,
  			subprog /* subprog number within this prog */);
  
  	/* Transfer references to the callee */
  	err = copy_reference_state(callee, caller);
  	if (err)
  		return err;
  
  	err = set_callee_state_cb(env, caller, callee, *insn_idx);
  	if (err)
  		return err;
  
  	clear_caller_saved_regs(env, caller->regs);
  
  	/* only increment it after check_reg_arg() finished */
  	state->curframe++;
  
  	/* and go analyze first insn of the callee */
  	*insn_idx = env->subprog_info[subprog].start - 1;
  
  	if (env->log.level & BPF_LOG_LEVEL) {
  		verbose(env, "caller:\n");
  		print_verifier_state(env, caller, true);
  		verbose(env, "callee:\n");
  		print_verifier_state(env, callee, true);
  	}
  	return 0;
  }
  
  int map_set_for_each_callback_args(struct bpf_verifier_env *env,
  				   struct bpf_func_state *caller,
  				   struct bpf_func_state *callee)
  {
  	/* bpf_for_each_map_elem(struct bpf_map *map, void *callback_fn,
  	 *      void *callback_ctx, u64 flags);
  	 * callback_fn(struct bpf_map *map, void *key, void *value,
  	 *      void *callback_ctx);
  	 */
  	callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1];
  
  	callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY;
  	__mark_reg_known_zero(&callee->regs[BPF_REG_2]);
  	callee->regs[BPF_REG_2].map_ptr = caller->regs[BPF_REG_1].map_ptr;
  
  	callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE;
  	__mark_reg_known_zero(&callee->regs[BPF_REG_3]);
  	callee->regs[BPF_REG_3].map_ptr = caller->regs[BPF_REG_1].map_ptr;
  
  	/* pointer to stack or null */
  	callee->regs[BPF_REG_4] = caller->regs[BPF_REG_3];
  
  	/* unused */
  	__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
  	return 0;
  }
  
  static int set_callee_state(struct bpf_verifier_env *env,
  			    struct bpf_func_state *caller,
  			    struct bpf_func_state *callee, int insn_idx)
  {
  	int i;
  
  	/* copy r1 - r5 args that callee can access.  The copy includes parent
  	 * pointers, which connects us up to the liveness chain
  	 */
  	for (i = BPF_REG_1; i <= BPF_REG_5; i++)
  		callee->regs[i] = caller->regs[i];
  	return 0;
  }
  
  static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
  			   int *insn_idx)
  {
  	int subprog, target_insn;
  
  	target_insn = *insn_idx + insn->imm + 1;
  	subprog = find_subprog(env, target_insn);
  	if (subprog < 0) {
  		verbose(env, "verifier bug. No program starts at insn %d\n",
  			target_insn);
  		return -EFAULT;
  	}
  
  	return __check_func_call(env, insn, insn_idx, subprog, set_callee_state);
  }
  
  static int set_map_elem_callback_state(struct bpf_verifier_env *env,
  				       struct bpf_func_state *caller,
  				       struct bpf_func_state *callee,
  				       int insn_idx)
  {
  	struct bpf_insn_aux_data *insn_aux = &env->insn_aux_data[insn_idx];
  	struct bpf_map *map;
  	int err;
  
  	if (bpf_map_ptr_poisoned(insn_aux)) {
  		verbose(env, "tail_call abusing map_ptr\n");
  		return -EINVAL;
  	}
  
  	map = BPF_MAP_PTR(insn_aux->map_ptr_state);
  	if (!map->ops->map_set_for_each_callback_args ||
  	    !map->ops->map_for_each_callback) {
  		verbose(env, "callback function not allowed for map\n");
  		return -ENOTSUPP;
  	}
  
  	err = map->ops->map_set_for_each_callback_args(env, caller, callee);
  	if (err)
  		return err;
  
  	callee->in_callback_fn = true;
  	return 0;
  }
  
  static int set_loop_callback_state(struct bpf_verifier_env *env,
  				   struct bpf_func_state *caller,
  				   struct bpf_func_state *callee,
  				   int insn_idx)
  {
  	/* bpf_loop(u32 nr_loops, void *callback_fn, void *callback_ctx,
  	 *	    u64 flags);
  	 * callback_fn(u32 index, void *callback_ctx);
  	 */
  	callee->regs[BPF_REG_1].type = SCALAR_VALUE;
  	callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3];
  
  	/* unused */
  	__mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
  	__mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
  	__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
  
  	callee->in_callback_fn = true;
  	return 0;
  }
  
  static int set_timer_callback_state(struct bpf_verifier_env *env,
  				    struct bpf_func_state *caller,
  				    struct bpf_func_state *callee,
  				    int insn_idx)
  {
  	struct bpf_map *map_ptr = caller->regs[BPF_REG_1].map_ptr;
  
  	/* bpf_timer_set_callback(struct bpf_timer *timer, void *callback_fn);
  	 * callback_fn(struct bpf_map *map, void *key, void *value);
  	 */
  	callee->regs[BPF_REG_1].type = CONST_PTR_TO_MAP;
  	__mark_reg_known_zero(&callee->regs[BPF_REG_1]);
  	callee->regs[BPF_REG_1].map_ptr = map_ptr;
  
  	callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY;
  	__mark_reg_known_zero(&callee->regs[BPF_REG_2]);
  	callee->regs[BPF_REG_2].map_ptr = map_ptr;
  
  	callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE;
  	__mark_reg_known_zero(&callee->regs[BPF_REG_3]);
  	callee->regs[BPF_REG_3].map_ptr = map_ptr;
  
  	/* unused */
  	__mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
  	__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
  	callee->in_async_callback_fn = true;
  	return 0;
  }
  
  static int set_find_vma_callback_state(struct bpf_verifier_env *env,
  				       struct bpf_func_state *caller,
  				       struct bpf_func_state *callee,
  				       int insn_idx)
  {
  	/* bpf_find_vma(struct task_struct *task, u64 addr,
  	 *               void *callback_fn, void *callback_ctx, u64 flags)
  	 * (callback_fn)(struct task_struct *task,
  	 *               struct vm_area_struct *vma, void *callback_ctx);
  	 */
  	callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1];
  
  	callee->regs[BPF_REG_2].type = PTR_TO_BTF_ID;
  	__mark_reg_known_zero(&callee->regs[BPF_REG_2]);
  	callee->regs[BPF_REG_2].btf =  btf_vmlinux;
  	callee->regs[BPF_REG_2].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_VMA],
  
  	/* pointer to stack or null */
  	callee->regs[BPF_REG_3] = caller->regs[BPF_REG_4];
  
  	/* unused */
  	__mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
  	__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
  	callee->in_callback_fn = true;
  	return 0;
  }
  
  static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
  {
  	struct bpf_verifier_state *state = env->cur_state;
  	struct bpf_func_state *caller, *callee;
  	struct bpf_reg_state *r0;
  	int err;
  
  	callee = state->frame[state->curframe];
  	r0 = &callee->regs[BPF_REG_0];
  	if (r0->type == PTR_TO_STACK) {
  		/* technically it's ok to return caller's stack pointer
  		 * (or caller's caller's pointer) back to the caller,
  		 * since these pointers are valid. Only current stack
  		 * pointer will be invalid as soon as function exits,
  		 * but let's be conservative
  		 */
  		verbose(env, "cannot return stack pointer to the caller\n");
  		return -EINVAL;
  	}
  
  	state->curframe--;
  	caller = state->frame[state->curframe];
  	if (callee->in_callback_fn) {
  		/* enforce R0 return value range [0, 1]. */
  		struct tnum range = tnum_range(0, 1);
  
  		if (r0->type != SCALAR_VALUE) {
  			verbose(env, "R0 not a scalar value\n");
  			return -EACCES;
  		}
  		if (!tnum_in(range, r0->var_off)) {
  			verbose_invalid_scalar(env, r0, &range, "callback return", "R0");
  			return -EINVAL;
  		}
  	} else {
  		/* return to the caller whatever r0 had in the callee */
  		caller->regs[BPF_REG_0] = *r0;
  	}
  
  	/* Transfer references to the caller */
  	err = copy_reference_state(caller, callee);
  	if (err)
  		return err;
  
  	*insn_idx = callee->callsite + 1;
  	if (env->log.level & BPF_LOG_LEVEL) {
  		verbose(env, "returning from callee:\n");
  		print_verifier_state(env, callee, true);
  		verbose(env, "to caller at %d:\n", *insn_idx);
  		print_verifier_state(env, caller, true);
  	}
  	/* clear everything in the callee */
  	free_func_state(callee);
  	state->frame[state->curframe + 1] = NULL;
  	return 0;
  }
  
  static void do_refine_retval_range(struct bpf_reg_state *regs, int ret_type,
  				   int func_id,
  				   struct bpf_call_arg_meta *meta)
  {
  	struct bpf_reg_state *ret_reg = &regs[BPF_REG_0];
  
  	if (ret_type != RET_INTEGER ||
  	    (func_id != BPF_FUNC_get_stack &&
  	     func_id != BPF_FUNC_get_task_stack &&
  	     func_id != BPF_FUNC_probe_read_str &&
  	     func_id != BPF_FUNC_probe_read_kernel_str &&
  	     func_id != BPF_FUNC_probe_read_user_str))
  		return;
  
  	ret_reg->smax_value = meta->msize_max_value;
  	ret_reg->s32_max_value = meta->msize_max_value;
  	ret_reg->smin_value = -MAX_ERRNO;
  	ret_reg->s32_min_value = -MAX_ERRNO;
  	__reg_deduce_bounds(ret_reg);
  	__reg_bound_offset(ret_reg);
  	__update_reg_bounds(ret_reg);
  }
  
  static int
  record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
  		int func_id, int insn_idx)
  {
  	struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
  	struct bpf_map *map = meta->map_ptr;
  
  	if (func_id != BPF_FUNC_tail_call &&
  	    func_id != BPF_FUNC_map_lookup_elem &&
  	    func_id != BPF_FUNC_map_update_elem &&
  	    func_id != BPF_FUNC_map_delete_elem &&
  	    func_id != BPF_FUNC_map_push_elem &&
  	    func_id != BPF_FUNC_map_pop_elem &&
  	    func_id != BPF_FUNC_map_peek_elem &&
  	    func_id != BPF_FUNC_for_each_map_elem &&
  	    func_id != BPF_FUNC_redirect_map)
  		return 0;
  
  	if (map == NULL) {
  		verbose(env, "kernel subsystem misconfigured verifier\n");
  		return -EINVAL;
  	}
  
  	/* In case of read-only, some additional restrictions
  	 * need to be applied in order to prevent altering the
  	 * state of the map from program side.
  	 */
  	if ((map->map_flags & BPF_F_RDONLY_PROG) &&
  	    (func_id == BPF_FUNC_map_delete_elem ||
  	     func_id == BPF_FUNC_map_update_elem ||
  	     func_id == BPF_FUNC_map_push_elem ||
  	     func_id == BPF_FUNC_map_pop_elem)) {
  		verbose(env, "write into map forbidden\n");
  		return -EACCES;
  	}
  
  	if (!BPF_MAP_PTR(aux->map_ptr_state))
  		bpf_map_ptr_store(aux, meta->map_ptr,
  				  !meta->map_ptr->bypass_spec_v1);
  	else if (BPF_MAP_PTR(aux->map_ptr_state) != meta->map_ptr)
  		bpf_map_ptr_store(aux, BPF_MAP_PTR_POISON,
  				  !meta->map_ptr->bypass_spec_v1);
  	return 0;
  }
  
  static int
  record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
  		int func_id, int insn_idx)
  {
  	struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
  	struct bpf_reg_state *regs = cur_regs(env), *reg;
  	struct bpf_map *map = meta->map_ptr;
  	struct tnum range;
  	u64 val;
  	int err;
  
  	if (func_id != BPF_FUNC_tail_call)
  		return 0;
  	if (!map || map->map_type != BPF_MAP_TYPE_PROG_ARRAY) {
  		verbose(env, "kernel subsystem misconfigured verifier\n");
  		return -EINVAL;
  	}
  
  	range = tnum_range(0, map->max_entries - 1);
  	reg = &regs[BPF_REG_3];
  
  	if (!register_is_const(reg) || !tnum_in(range, reg->var_off)) {
  		bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
  		return 0;
  	}
  
  	err = mark_chain_precision(env, BPF_REG_3);
  	if (err)
  		return err;
  
  	val = reg->var_off.value;
  	if (bpf_map_key_unseen(aux))
  		bpf_map_key_store(aux, val);
  	else if (!bpf_map_key_poisoned(aux) &&
  		  bpf_map_key_immediate(aux) != val)
  		bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
  	return 0;
  }
  
  static int check_reference_leak(struct bpf_verifier_env *env)
  {
  	struct bpf_func_state *state = cur_func(env);
  	int i;
  
  	for (i = 0; i < state->acquired_refs; i++) {
  		verbose(env, "Unreleased reference id=%d alloc_insn=%d\n",
  			state->refs[i].id, state->refs[i].insn_idx);
  	}
  	return state->acquired_refs ? -EINVAL : 0;
  }
  
  static int check_bpf_snprintf_call(struct bpf_verifier_env *env,
  				   struct bpf_reg_state *regs)
  {
  	struct bpf_reg_state *fmt_reg = &regs[BPF_REG_3];
  	struct bpf_reg_state *data_len_reg = &regs[BPF_REG_5];
  	struct bpf_map *fmt_map = fmt_reg->map_ptr;
  	int err, fmt_map_off, num_args;
  	u64 fmt_addr;
  	char *fmt;
  
  	/* data must be an array of u64 */
  	if (data_len_reg->var_off.value % 8)
  		return -EINVAL;
  	num_args = data_len_reg->var_off.value / 8;
  
  	/* fmt being ARG_PTR_TO_CONST_STR guarantees that var_off is const
  	 * and map_direct_value_addr is set.
  	 */
  	fmt_map_off = fmt_reg->off + fmt_reg->var_off.value;
  	err = fmt_map->ops->map_direct_value_addr(fmt_map, &fmt_addr,
  						  fmt_map_off);
  	if (err) {
  		verbose(env, "verifier bug\n");
  		return -EFAULT;
  	}
  	fmt = (char *)(long)fmt_addr + fmt_map_off;
  
  	/* We are also guaranteed that fmt+fmt_map_off is NULL terminated, we
  	 * can focus on validating the format specifiers.
  	 */
  	err = bpf_bprintf_prepare(fmt, UINT_MAX, NULL, NULL, num_args);
  	if (err < 0)
  		verbose(env, "Invalid format string\n");
  
  	return err;
  }
  
  static int check_get_func_ip(struct bpf_verifier_env *env)
  {
  	enum bpf_prog_type type = resolve_prog_type(env->prog);
  	int func_id = BPF_FUNC_get_func_ip;
  
  	if (type == BPF_PROG_TYPE_TRACING) {
  		if (!bpf_prog_has_trampoline(env->prog)) {
  			verbose(env, "func %s#%d supported only for fentry/fexit/fmod_ret programs\n",
  				func_id_name(func_id), func_id);
  			return -ENOTSUPP;
  		}
  		return 0;
  	} else if (type == BPF_PROG_TYPE_KPROBE) {
  		return 0;
  	}
  
  	verbose(env, "func %s#%d not supported for program type %d\n",
  		func_id_name(func_id), func_id, type);
  	return -ENOTSUPP;
  }
  
  static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
  			     int *insn_idx_p)
  {
  	const struct bpf_func_proto *fn = NULL;
  	enum bpf_return_type ret_type;
  	enum bpf_type_flag ret_flag;
  	struct bpf_reg_state *regs;
  	struct bpf_call_arg_meta meta;
  	int insn_idx = *insn_idx_p;
  	bool changes_data;
  	int i, err, func_id;
  
  	/* find function prototype */
  	func_id = insn->imm;
  	if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
  		verbose(env, "invalid func %s#%d\n", func_id_name(func_id),
  			func_id);
  		return -EINVAL;
  	}
  
  	if (env->ops->get_func_proto)
  		fn = env->ops->get_func_proto(func_id, env->prog);
  	if (!fn) {
  		verbose(env, "unknown func %s#%d\n", func_id_name(func_id),
  			func_id);
  		return -EINVAL;
  	}
  
  	/* eBPF programs must be GPL compatible to use GPL-ed functions */
  	if (!env->prog->gpl_compatible && fn->gpl_only) {
  		verbose(env, "cannot call GPL-restricted function from non-GPL compatible program\n");
  		return -EINVAL;
  	}
  
  	if (fn->allowed && !fn->allowed(env->prog)) {
  		verbose(env, "helper call is not allowed in probe\n");
  		return -EINVAL;
  	}
  
  	/* With LD_ABS/IND some JITs save/restore skb from r1. */
  	changes_data = bpf_helper_changes_pkt_data(fn->func);
  	if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) {
  		verbose(env, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n",
  			func_id_name(func_id), func_id);
  		return -EINVAL;
  	}
  
  	memset(&meta, 0, sizeof(meta));
  	meta.pkt_access = fn->pkt_access;
  
  	err = check_func_proto(fn, func_id);
  	if (err) {
  		verbose(env, "kernel subsystem misconfigured func %s#%d\n",
  			func_id_name(func_id), func_id);
  		return err;
  	}
  
  	meta.func_id = func_id;
  	/* check args */
  	for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) {
  		err = check_func_arg(env, i, &meta, fn);
  		if (err)
  			return err;
  	}
  
  	err = record_func_map(env, &meta, func_id, insn_idx);
  	if (err)
  		return err;
  
  	err = record_func_key(env, &meta, func_id, insn_idx);
  	if (err)
  		return err;
  
  	/* Mark slots with STACK_MISC in case of raw mode, stack offset
  	 * is inferred from register state.
  	 */
  	for (i = 0; i < meta.access_size; i++) {
  		err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B,
  				       BPF_WRITE, -1, false);
  		if (err)
  			return err;
  	}
  
  	if (is_release_function(func_id)) {
  		err = release_reference(env, meta.ref_obj_id);
  		if (err) {
  			verbose(env, "func %s#%d reference has not been acquired before\n",
  				func_id_name(func_id), func_id);
  			return err;
  		}
  	}
  
  	regs = cur_regs(env);
  
  	switch (func_id) {
  	case BPF_FUNC_tail_call:
  		err = check_reference_leak(env);
  		if (err) {
  			verbose(env, "tail_call would lead to reference leak\n");
  			return err;
  		}
  		break;
  	case BPF_FUNC_get_local_storage:
  		/* check that flags argument in get_local_storage(map, flags) is 0,
  		 * this is required because get_local_storage() can't return an error.
  		 */
  		if (!register_is_null(&regs[BPF_REG_2])) {
  			verbose(env, "get_local_storage() doesn't support non-zero flags\n");
  			return -EINVAL;
  		}
  		break;
  	case BPF_FUNC_for_each_map_elem:
  		err = __check_func_call(env, insn, insn_idx_p, meta.subprogno,
  					set_map_elem_callback_state);
  		break;
  	case BPF_FUNC_timer_set_callback:
  		err = __check_func_call(env, insn, insn_idx_p, meta.subprogno,
  					set_timer_callback_state);
  		break;
  	case BPF_FUNC_find_vma:
  		err = __check_func_call(env, insn, insn_idx_p, meta.subprogno,
  					set_find_vma_callback_state);
  		break;
  	case BPF_FUNC_snprintf:
  		err = check_bpf_snprintf_call(env, regs);
  		break;
  	case BPF_FUNC_loop:
  		err = __check_func_call(env, insn, insn_idx_p, meta.subprogno,
  					set_loop_callback_state);
  		break;
  	}
  
  	if (err)
  		return err;
  
  	/* reset caller saved regs */
  	for (i = 0; i < CALLER_SAVED_REGS; i++) {
  		mark_reg_not_init(env, regs, caller_saved[i]);
  		check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
  	}
  
  	/* helper call returns 64-bit value. */
  	regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;
  
  	/* update return register (already marked as written above) */
  	ret_type = fn->ret_type;
  	ret_flag = type_flag(fn->ret_type);
  	if (ret_type == RET_INTEGER) {
  		/* sets type to SCALAR_VALUE */
  		mark_reg_unknown(env, regs, BPF_REG_0);
  	} else if (ret_type == RET_VOID) {
  		regs[BPF_REG_0].type = NOT_INIT;
  	} else if (base_type(ret_type) == RET_PTR_TO_MAP_VALUE) {
  		/* There is no offset yet applied, variable or fixed */
  		mark_reg_known_zero(env, regs, BPF_REG_0);
  		/* remember map_ptr, so that check_map_access()
  		 * can check 'value_size' boundary of memory access
  		 * to map element returned from bpf_map_lookup_elem()
  		 */
  		if (meta.map_ptr == NULL) {
  			verbose(env,
  				"kernel subsystem misconfigured verifier\n");
  			return -EINVAL;
  		}
  		regs[BPF_REG_0].map_ptr = meta.map_ptr;
  		regs[BPF_REG_0].map_uid = meta.map_uid;
  		regs[BPF_REG_0].type = PTR_TO_MAP_VALUE | ret_flag;
  		if (!type_may_be_null(ret_type) &&
  		    map_value_has_spin_lock(meta.map_ptr)) {
  			regs[BPF_REG_0].id = ++env->id_gen;
  		}
  	} else if (base_type(ret_type) == RET_PTR_TO_SOCKET) {
  		mark_reg_known_zero(env, regs, BPF_REG_0);
  		regs[BPF_REG_0].type = PTR_TO_SOCKET | ret_flag;
  	} else if (base_type(ret_type) == RET_PTR_TO_SOCK_COMMON) {
  		mark_reg_known_zero(env, regs, BPF_REG_0);
  		regs[BPF_REG_0].type = PTR_TO_SOCK_COMMON | ret_flag;
  	} else if (base_type(ret_type) == RET_PTR_TO_TCP_SOCK) {
  		mark_reg_known_zero(env, regs, BPF_REG_0);
  		regs[BPF_REG_0].type = PTR_TO_TCP_SOCK | ret_flag;
  	} else if (base_type(ret_type) == RET_PTR_TO_ALLOC_MEM) {
  		mark_reg_known_zero(env, regs, BPF_REG_0);
  		regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
  		regs[BPF_REG_0].mem_size = meta.mem_size;
  	} else if (base_type(ret_type) == RET_PTR_TO_MEM_OR_BTF_ID) {
  		const struct btf_type *t;
  
  		mark_reg_known_zero(env, regs, BPF_REG_0);
  		t = btf_type_skip_modifiers(meta.ret_btf, meta.ret_btf_id, NULL);
  		if (!btf_type_is_struct(t)) {
  			u32 tsize;
  			const struct btf_type *ret;
  			const char *tname;
  
  			/* resolve the type size of ksym. */
  			ret = btf_resolve_size(meta.ret_btf, t, &tsize);
  			if (IS_ERR(ret)) {
  				tname = btf_name_by_offset(meta.ret_btf, t->name_off);
  				verbose(env, "unable to resolve the size of type '%s': %ld\n",
  					tname, PTR_ERR(ret));
  				return -EINVAL;
  			}
  			regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
  			regs[BPF_REG_0].mem_size = tsize;
  		} else {
  			/* MEM_RDONLY may be carried from ret_flag, but it
  			 * doesn't apply on PTR_TO_BTF_ID. Fold it, otherwise
  			 * it will confuse the check of PTR_TO_BTF_ID in
  			 * check_mem_access().
  			 */
  			ret_flag &= ~MEM_RDONLY;
  
  			regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag;
  			regs[BPF_REG_0].btf = meta.ret_btf;
  			regs[BPF_REG_0].btf_id = meta.ret_btf_id;
  		}
  	} else if (base_type(ret_type) == RET_PTR_TO_BTF_ID) {
  		int ret_btf_id;
  
  		mark_reg_known_zero(env, regs, BPF_REG_0);
  		regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag;
  		ret_btf_id = *fn->ret_btf_id;
  		if (ret_btf_id == 0) {
  			verbose(env, "invalid return type %u of func %s#%d\n",
  				base_type(ret_type), func_id_name(func_id),
  				func_id);
  			return -EINVAL;
  		}
  		/* current BPF helper definitions are only coming from
  		 * built-in code with type IDs from  vmlinux BTF
  		 */
  		regs[BPF_REG_0].btf = btf_vmlinux;
  		regs[BPF_REG_0].btf_id = ret_btf_id;
  	} else {
  		verbose(env, "unknown return type %u of func %s#%d\n",
  			base_type(ret_type), func_id_name(func_id), func_id);
  		return -EINVAL;
  	}
  
  	if (type_may_be_null(regs[BPF_REG_0].type))
  		regs[BPF_REG_0].id = ++env->id_gen;
  
  	if (is_ptr_cast_function(func_id)) {
  		/* For release_reference() */
  		regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id;
  	} else if (is_acquire_function(func_id, meta.map_ptr)) {
  		int id = acquire_reference_state(env, insn_idx);
  
  		if (id < 0)
  			return id;
  		/* For mark_ptr_or_null_reg() */
  		regs[BPF_REG_0].id = id;
  		/* For release_reference() */
  		regs[BPF_REG_0].ref_obj_id = id;
  	}
  
  	do_refine_retval_range(regs, fn->ret_type, func_id, &meta);
  
  	err = check_map_func_compatibility(env, meta.map_ptr, func_id);
  	if (err)
  		return err;
  
  	if ((func_id == BPF_FUNC_get_stack ||
  	     func_id == BPF_FUNC_get_task_stack) &&
  	    !env->prog->has_callchain_buf) {
  		const char *err_str;
  
  #ifdef CONFIG_PERF_EVENTS
  		err = get_callchain_buffers(sysctl_perf_event_max_stack);
  		err_str = "cannot get callchain buffer for func %s#%d\n";
  #else
  		err = -ENOTSUPP;
  		err_str = "func %s#%d not supported without CONFIG_PERF_EVENTS\n";
  #endif
  		if (err) {
  			verbose(env, err_str, func_id_name(func_id), func_id);
  			return err;
  		}
  
  		env->prog->has_callchain_buf = true;
  	}
  
  	if (func_id == BPF_FUNC_get_stackid || func_id == BPF_FUNC_get_stack)
  		env->prog->call_get_stack = true;
  
  	if (func_id == BPF_FUNC_get_func_ip) {
  		if (check_get_func_ip(env))
  			return -ENOTSUPP;
  		env->prog->call_get_func_ip = true;
  	}
  
  	if (changes_data)
  		clear_all_pkt_pointers(env);
  	return 0;
  }
  
  /* mark_btf_func_reg_size() is used when the reg size is determined by
   * the BTF func_proto's return value size and argument.
   */
  static void mark_btf_func_reg_size(struct bpf_verifier_env *env, u32 regno,
  				   size_t reg_size)
  {
  	struct bpf_reg_state *reg = &cur_regs(env)[regno];
  
  	if (regno == BPF_REG_0) {
  		/* Function return value */
  		reg->live |= REG_LIVE_WRITTEN;
  		reg->subreg_def = reg_size == sizeof(u64) ?
  			DEF_NOT_SUBREG : env->insn_idx + 1;
  	} else {
  		/* Function argument */
  		if (reg_size == sizeof(u64)) {
  			mark_insn_zext(env, reg);
  			mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
  		} else {
  			mark_reg_read(env, reg, reg->parent, REG_LIVE_READ32);
  		}
  	}
  }
  
  static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
  			    int *insn_idx_p)
  {
  	const struct btf_type *t, *func, *func_proto, *ptr_type;
  	struct bpf_reg_state *regs = cur_regs(env);
  	const char *func_name, *ptr_type_name;
  	u32 i, nargs, func_id, ptr_type_id;
  	int err, insn_idx = *insn_idx_p;
  	const struct btf_param *args;
  	struct btf *desc_btf;
  	bool acq;
  
  	/* skip for now, but return error when we find this in fixup_kfunc_call */
  	if (!insn->imm)
  		return 0;
  
  	desc_btf = find_kfunc_desc_btf(env, insn->imm, insn->off);
  	if (IS_ERR(desc_btf))
  		return PTR_ERR(desc_btf);
  
  	func_id = insn->imm;
  	func = btf_type_by_id(desc_btf, func_id);
  	func_name = btf_name_by_offset(desc_btf, func->name_off);
  	func_proto = btf_type_by_id(desc_btf, func->type);
  
  	if (!btf_kfunc_id_set_contains(desc_btf, resolve_prog_type(env->prog),
  				      BTF_KFUNC_TYPE_CHECK, func_id)) {
  		verbose(env, "calling kernel function %s is not allowed\n",
  			func_name);
  		return -EACCES;
  	}
  
  	acq = btf_kfunc_id_set_contains(desc_btf, resolve_prog_type(env->prog),
  					BTF_KFUNC_TYPE_ACQUIRE, func_id);
  
  	/* Check the arguments */
  	err = btf_check_kfunc_arg_match(env, desc_btf, func_id, regs);
  	if (err < 0)
  		return err;
  	/* In case of release function, we get register number of refcounted
  	 * PTR_TO_BTF_ID back from btf_check_kfunc_arg_match, do the release now
  	 */
  	if (err) {
  		err = release_reference(env, regs[err].ref_obj_id);
  		if (err) {
  			verbose(env, "kfunc %s#%d reference has not been acquired before\n",
  				func_name, func_id);
  			return err;
  		}
  	}
  
  	for (i = 0; i < CALLER_SAVED_REGS; i++)
  		mark_reg_not_init(env, regs, caller_saved[i]);
  
  	/* Check return type */
  	t = btf_type_skip_modifiers(desc_btf, func_proto->type, NULL);
  
  	if (acq && !btf_type_is_ptr(t)) {
  		verbose(env, "acquire kernel function does not return PTR_TO_BTF_ID\n");
  		return -EINVAL;
  	}
  
  	if (btf_type_is_scalar(t)) {
  		mark_reg_unknown(env, regs, BPF_REG_0);
  		mark_btf_func_reg_size(env, BPF_REG_0, t->size);
  	} else if (btf_type_is_ptr(t)) {
  		ptr_type = btf_type_skip_modifiers(desc_btf, t->type,
  						   &ptr_type_id);
  		if (!btf_type_is_struct(ptr_type)) {
  			ptr_type_name = btf_name_by_offset(desc_btf,
  							   ptr_type->name_off);
  			verbose(env, "kernel function %s returns pointer type %s %s is not supported\n",
  				func_name, btf_type_str(ptr_type),
  				ptr_type_name);
  			return -EINVAL;
  		}
  		mark_reg_known_zero(env, regs, BPF_REG_0);
  		regs[BPF_REG_0].btf = desc_btf;
  		regs[BPF_REG_0].type = PTR_TO_BTF_ID;
  		regs[BPF_REG_0].btf_id = ptr_type_id;
  		if (btf_kfunc_id_set_contains(desc_btf, resolve_prog_type(env->prog),
  					      BTF_KFUNC_TYPE_RET_NULL, func_id)) {
  			regs[BPF_REG_0].type |= PTR_MAYBE_NULL;
  			/* For mark_ptr_or_null_reg, see 93c230e3f5bd6 */
  			regs[BPF_REG_0].id = ++env->id_gen;
  		}
  		mark_btf_func_reg_size(env, BPF_REG_0, sizeof(void *));
  		if (acq) {
  			int id = acquire_reference_state(env, insn_idx);
  
  			if (id < 0)
  				return id;
  			regs[BPF_REG_0].id = id;
  			regs[BPF_REG_0].ref_obj_id = id;
  		}
  	} /* else { add_kfunc_call() ensures it is btf_type_is_void(t) } */
  
  	nargs = btf_type_vlen(func_proto);
  	args = (const struct btf_param *)(func_proto + 1);
  	for (i = 0; i < nargs; i++) {
  		u32 regno = i + 1;
  
  		t = btf_type_skip_modifiers(desc_btf, args[i].type, NULL);
  		if (btf_type_is_ptr(t))
  			mark_btf_func_reg_size(env, regno, sizeof(void *));
  		else
  			/* scalar. ensured by btf_check_kfunc_arg_match() */
  			mark_btf_func_reg_size(env, regno, t->size);
  	}
  
  	return 0;
  }
  
  static bool signed_add_overflows(s64 a, s64 b)
  {
  	/* Do the add in u64, where overflow is well-defined */
  	s64 res = (s64)((u64)a + (u64)b);
  
  	if (b < 0)
  		return res > a;
  	return res < a;
  }
  
  static bool signed_add32_overflows(s32 a, s32 b)
  {
  	/* Do the add in u32, where overflow is well-defined */
  	s32 res = (s32)((u32)a + (u32)b);
  
  	if (b < 0)
  		return res > a;
  	return res < a;
  }
  
  static bool signed_sub_overflows(s64 a, s64 b)
  {
  	/* Do the sub in u64, where overflow is well-defined */
  	s64 res = (s64)((u64)a - (u64)b);
  
  	if (b < 0)
  		return res < a;
  	return res > a;
  }
  
  static bool signed_sub32_overflows(s32 a, s32 b)
  {
  	/* Do the sub in u32, where overflow is well-defined */
  	s32 res = (s32)((u32)a - (u32)b);
  
  	if (b < 0)
  		return res < a;
  	return res > a;
  }
  
  static bool check_reg_sane_offset(struct bpf_verifier_env *env,
  				  const struct bpf_reg_state *reg,
  				  enum bpf_reg_type type)
  {
  	bool known = tnum_is_const(reg->var_off);
  	s64 val = reg->var_off.value;
  	s64 smin = reg->smin_value;
  
  	if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) {
  		verbose(env, "math between %s pointer and %lld is not allowed\n",
  			reg_type_str(env, type), val);
  		return false;
  	}
  
  	if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) {
  		verbose(env, "%s pointer offset %d is not allowed\n",
  			reg_type_str(env, type), reg->off);
  		return false;
  	}
  
  	if (smin == S64_MIN) {
  		verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n",
  			reg_type_str(env, type));
  		return false;
  	}
  
  	if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) {
  		verbose(env, "value %lld makes %s pointer be out of bounds\n",
  			smin, reg_type_str(env, type));
  		return false;
  	}
  
  	return true;
  }
  
  static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env)
  {
  	return &env->insn_aux_data[env->insn_idx];
  }
  
  enum {
  	REASON_BOUNDS	= -1,
  	REASON_TYPE	= -2,
  	REASON_PATHS	= -3,
  	REASON_LIMIT	= -4,
  	REASON_STACK	= -5,
  };
  
  static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg,
  			      u32 *alu_limit, bool mask_to_left)
  {
  	u32 max = 0, ptr_limit = 0;
  
  	switch (ptr_reg->type) {
  	case PTR_TO_STACK:
  		/* Offset 0 is out-of-bounds, but acceptable start for the
  		 * left direction, see BPF_REG_FP. Also, unknown scalar
  		 * offset where we would need to deal with min/max bounds is
  		 * currently prohibited for unprivileged.
  		 */
  		max = MAX_BPF_STACK + mask_to_left;
  		ptr_limit = -(ptr_reg->var_off.value + ptr_reg->off);
  		break;
  	case PTR_TO_MAP_VALUE:
  		max = ptr_reg->map_ptr->value_size;
  		ptr_limit = (mask_to_left ?
  			     ptr_reg->smin_value :
  			     ptr_reg->umax_value) + ptr_reg->off;
  		break;
  	default:
  		return REASON_TYPE;
  	}
  
  	if (ptr_limit >= max)
  		return REASON_LIMIT;
  	*alu_limit = ptr_limit;
  	return 0;
  }
  
  static bool can_skip_alu_sanitation(const struct bpf_verifier_env *env,
  				    const struct bpf_insn *insn)
  {
  	return env->bypass_spec_v1 || BPF_SRC(insn->code) == BPF_K;
  }
  
  static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux,
  				       u32 alu_state, u32 alu_limit)
  {
  	/* If we arrived here from different branches with different
  	 * state or limits to sanitize, then this won't work.
  	 */
  	if (aux->alu_state &&
  	    (aux->alu_state != alu_state ||
  	     aux->alu_limit != alu_limit))
  		return REASON_PATHS;
  
  	/* Corresponding fixup done in do_misc_fixups(). */
  	aux->alu_state = alu_state;
  	aux->alu_limit = alu_limit;
  	return 0;
  }
  
  static int sanitize_val_alu(struct bpf_verifier_env *env,
  			    struct bpf_insn *insn)
  {
  	struct bpf_insn_aux_data *aux = cur_aux(env);
  
  	if (can_skip_alu_sanitation(env, insn))
  		return 0;
  
  	return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0);
  }
  
  static bool sanitize_needed(u8 opcode)
  {
  	return opcode == BPF_ADD || opcode == BPF_SUB;
  }
  
  struct bpf_sanitize_info {
  	struct bpf_insn_aux_data aux;
  	bool mask_to_left;
  };
  
  static struct bpf_verifier_state *
  sanitize_speculative_path(struct bpf_verifier_env *env,
  			  const struct bpf_insn *insn,
  			  u32 next_idx, u32 curr_idx)
  {
  	struct bpf_verifier_state *branch;
  	struct bpf_reg_state *regs;
  
  	branch = push_stack(env, next_idx, curr_idx, true);
  	if (branch && insn) {
  		regs = branch->frame[branch->curframe]->regs;
  		if (BPF_SRC(insn->code) == BPF_K) {
  			mark_reg_unknown(env, regs, insn->dst_reg);
  		} else if (BPF_SRC(insn->code) == BPF_X) {
  			mark_reg_unknown(env, regs, insn->dst_reg);
  			mark_reg_unknown(env, regs, insn->src_reg);
  		}
  	}
  	return branch;
  }
  
  static int sanitize_ptr_alu(struct bpf_verifier_env *env,
  			    struct bpf_insn *insn,
  			    const struct bpf_reg_state *ptr_reg,
  			    const struct bpf_reg_state *off_reg,
  			    struct bpf_reg_state *dst_reg,
  			    struct bpf_sanitize_info *info,
  			    const bool commit_window)
  {
  	struct bpf_insn_aux_data *aux = commit_window ? cur_aux(env) : &info->aux;
  	struct bpf_verifier_state *vstate = env->cur_state;
  	bool off_is_imm = tnum_is_const(off_reg->var_off);
  	bool off_is_neg = off_reg->smin_value < 0;
  	bool ptr_is_dst_reg = ptr_reg == dst_reg;
  	u8 opcode = BPF_OP(insn->code);
  	u32 alu_state, alu_limit;
  	struct bpf_reg_state tmp;
  	bool ret;
  	int err;
  
  	if (can_skip_alu_sanitation(env, insn))
  		return 0;
  
  	/* We already marked aux for masking from non-speculative
  	 * paths, thus we got here in the first place. We only care
  	 * to explore bad access from here.
  	 */
  	if (vstate->speculative)
  		goto do_sim;
  
  	if (!commit_window) {
  		if (!tnum_is_const(off_reg->var_off) &&
  		    (off_reg->smin_value < 0) != (off_reg->smax_value < 0))
  			return REASON_BOUNDS;
  
  		info->mask_to_left = (opcode == BPF_ADD &&  off_is_neg) ||
  				     (opcode == BPF_SUB && !off_is_neg);
  	}
  
  	err = retrieve_ptr_limit(ptr_reg, &alu_limit, info->mask_to_left);
  	if (err < 0)
  		return err;
  
  	if (commit_window) {
  		/* In commit phase we narrow the masking window based on
  		 * the observed pointer move after the simulated operation.
  		 */
  		alu_state = info->aux.alu_state;
  		alu_limit = abs(info->aux.alu_limit - alu_limit);
  	} else {
  		alu_state  = off_is_neg ? BPF_ALU_NEG_VALUE : 0;
  		alu_state |= off_is_imm ? BPF_ALU_IMMEDIATE : 0;
  		alu_state |= ptr_is_dst_reg ?
  			     BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST;
  
  		/* Limit pruning on unknown scalars to enable deep search for
  		 * potential masking differences from other program paths.
  		 */
  		if (!off_is_imm)
  			env->explore_alu_limits = true;
  	}
  
  	err = update_alu_sanitation_state(aux, alu_state, alu_limit);
  	if (err < 0)
  		return err;
  do_sim:
  	/* If we're in commit phase, we're done here given we already
  	 * pushed the truncated dst_reg into the speculative verification
  	 * stack.
  	 *
  	 * Also, when register is a known constant, we rewrite register-based
  	 * operation to immediate-based, and thus do not need masking (and as
  	 * a consequence, do not need to simulate the zero-truncation either).
  	 */
  	if (commit_window || off_is_imm)
  		return 0;
  
  	/* Simulate and find potential out-of-bounds access under
  	 * speculative execution from truncation as a result of
  	 * masking when off was not within expected range. If off
  	 * sits in dst, then we temporarily need to move ptr there
  	 * to simulate dst (== 0) +/-= ptr. Needed, for example,
  	 * for cases where we use K-based arithmetic in one direction
  	 * and truncated reg-based in the other in order to explore
  	 * bad access.
  	 */
  	if (!ptr_is_dst_reg) {
  		tmp = *dst_reg;
  		*dst_reg = *ptr_reg;
  	}
  	ret = sanitize_speculative_path(env, NULL, env->insn_idx + 1,
  					env->insn_idx);
  	if (!ptr_is_dst_reg && ret)
  		*dst_reg = tmp;
  	return !ret ? REASON_STACK : 0;
  }
  
  static void sanitize_mark_insn_seen(struct bpf_verifier_env *env)
  {
  	struct bpf_verifier_state *vstate = env->cur_state;
  
  	/* If we simulate paths under speculation, we don't update the
  	 * insn as 'seen' such that when we verify unreachable paths in
  	 * the non-speculative domain, sanitize_dead_code() can still
  	 * rewrite/sanitize them.
  	 */
  	if (!vstate->speculative)
  		env->insn_aux_data[env->insn_idx].seen = env->pass_cnt;
  }
  
  static int sanitize_err(struct bpf_verifier_env *env,
  			const struct bpf_insn *insn, int reason,
  			const struct bpf_reg_state *off_reg,
  			const struct bpf_reg_state *dst_reg)
  {
  	static const char *err = "pointer arithmetic with it prohibited for !root";
  	const char *op = BPF_OP(insn->code) == BPF_ADD ? "add" : "sub";
  	u32 dst = insn->dst_reg, src = insn->src_reg;
  
  	switch (reason) {
  	case REASON_BOUNDS:
  		verbose(env, "R%d has unknown scalar with mixed signed bounds, %s\n",
  			off_reg == dst_reg ? dst : src, err);
  		break;
  	case REASON_TYPE:
  		verbose(env, "R%d has pointer with unsupported alu operation, %s\n",
  			off_reg == dst_reg ? src : dst, err);
  		break;
  	case REASON_PATHS:
  		verbose(env, "R%d tried to %s from different maps, paths or scalars, %s\n",
  			dst, op, err);
  		break;
  	case REASON_LIMIT:
  		verbose(env, "R%d tried to %s beyond pointer bounds, %s\n",
  			dst, op, err);
  		break;
  	case REASON_STACK:
  		verbose(env, "R%d could not be pushed for speculative verification, %s\n",
  			dst, err);
  		break;
  	default:
  		verbose(env, "verifier internal error: unknown reason (%d)\n",
  			reason);
  		break;
  	}
  
  	return -EACCES;
  }
  
  /* check that stack access falls within stack limits and that 'reg' doesn't
   * have a variable offset.
   *
   * Variable offset is prohibited for unprivileged mode for simplicity since it
   * requires corresponding support in Spectre masking for stack ALU.  See also
   * retrieve_ptr_limit().
   *
   *
   * 'off' includes 'reg->off'.
   */
  static int check_stack_access_for_ptr_arithmetic(
  				struct bpf_verifier_env *env,
  				int regno,
  				const struct bpf_reg_state *reg,
  				int off)
  {
  	if (!tnum_is_const(reg->var_off)) {
  		char tn_buf[48];
  
  		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  		verbose(env, "R%d variable stack access prohibited for !root, var_off=%s off=%d\n",
  			regno, tn_buf, off);
  		return -EACCES;
  	}
  
  	if (off >= 0 || off < -MAX_BPF_STACK) {
  		verbose(env, "R%d stack pointer arithmetic goes out of range, "
  			"prohibited for !root; off=%d\n", regno, off);
  		return -EACCES;
  	}
  
  	return 0;
  }
  
  static int sanitize_check_bounds(struct bpf_verifier_env *env,
  				 const struct bpf_insn *insn,
  				 const struct bpf_reg_state *dst_reg)
  {
  	u32 dst = insn->dst_reg;
  
  	/* For unprivileged we require that resulting offset must be in bounds
  	 * in order to be able to sanitize access later on.
  	 */
  	if (env->bypass_spec_v1)
  		return 0;
  
  	switch (dst_reg->type) {
  	case PTR_TO_STACK:
  		if (check_stack_access_for_ptr_arithmetic(env, dst, dst_reg,
  					dst_reg->off + dst_reg->var_off.value))
  			return -EACCES;
  		break;
  	case PTR_TO_MAP_VALUE:
  		if (check_map_access(env, dst, dst_reg->off, 1, false)) {
  			verbose(env, "R%d pointer arithmetic of map value goes out of range, "
  				"prohibited for !root\n", dst);
  			return -EACCES;
  		}
  		break;
  	default:
  		break;
  	}
  
  	return 0;
  }
  
  /* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
   * Caller should also handle BPF_MOV case separately.
   * If we return -EACCES, caller may want to try again treating pointer as a
   * scalar.  So we only emit a diagnostic if !env->allow_ptr_leaks.
   */
  static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
  				   struct bpf_insn *insn,
  				   const struct bpf_reg_state *ptr_reg,
  				   const struct bpf_reg_state *off_reg)
  {
  	struct bpf_verifier_state *vstate = env->cur_state;
  	struct bpf_func_state *state = vstate->frame[vstate->curframe];
  	struct bpf_reg_state *regs = state->regs, *dst_reg;
  	bool known = tnum_is_const(off_reg->var_off);
  	s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value,
  	    smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value;
  	u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value,
  	    umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value;
  	struct bpf_sanitize_info info = {};
  	u8 opcode = BPF_OP(insn->code);
  	u32 dst = insn->dst_reg;
  	int ret;
  
  	dst_reg = &regs[dst];
  
  	if ((known && (smin_val != smax_val || umin_val != umax_val)) ||
  	    smin_val > smax_val || umin_val > umax_val) {
  		/* Taint dst register if offset had invalid bounds derived from
  		 * e.g. dead branches.
  		 */
  		__mark_reg_unknown(env, dst_reg);
  		return 0;
  	}
  
  	if (BPF_CLASS(insn->code) != BPF_ALU64) {
  		/* 32-bit ALU ops on pointers produce (meaningless) scalars */
  		if (opcode == BPF_SUB && env->allow_ptr_leaks) {
  			__mark_reg_unknown(env, dst_reg);
  			return 0;
  		}
  
  		verbose(env,
  			"R%d 32-bit pointer arithmetic prohibited\n",
  			dst);
  		return -EACCES;
  	}
  
  	if (ptr_reg->type & PTR_MAYBE_NULL) {
  		verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n",
  			dst, reg_type_str(env, ptr_reg->type));
  		return -EACCES;
  	}
  
  	switch (base_type(ptr_reg->type)) {
  	case CONST_PTR_TO_MAP:
  		/* smin_val represents the known value */
  		if (known && smin_val == 0 && opcode == BPF_ADD)
  			break;
  		fallthrough;
  	case PTR_TO_PACKET_END:
  	case PTR_TO_SOCKET:
  	case PTR_TO_SOCK_COMMON:
  	case PTR_TO_TCP_SOCK:
  	case PTR_TO_XDP_SOCK:
  		verbose(env, "R%d pointer arithmetic on %s prohibited\n",
  			dst, reg_type_str(env, ptr_reg->type));
  		return -EACCES;
  	default:
  		break;
  	}
  
  	/* In case of 'scalar += pointer', dst_reg inherits pointer type and id.
  	 * The id may be overwritten later if we create a new variable offset.
  	 */
  	dst_reg->type = ptr_reg->type;
  	dst_reg->id = ptr_reg->id;
  
  	if (!check_reg_sane_offset(env, off_reg, ptr_reg->type) ||
  	    !check_reg_sane_offset(env, ptr_reg, ptr_reg->type))
  		return -EINVAL;
  
  	/* pointer types do not carry 32-bit bounds at the moment. */
  	__mark_reg32_unbounded(dst_reg);
  
  	if (sanitize_needed(opcode)) {
  		ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg,
  				       &info, false);
  		if (ret < 0)
  			return sanitize_err(env, insn, ret, off_reg, dst_reg);
  	}
  
  	switch (opcode) {
  	case BPF_ADD:
  		/* We can take a fixed offset as long as it doesn't overflow
  		 * the s32 'off' field
  		 */
  		if (known && (ptr_reg->off + smin_val ==
  			      (s64)(s32)(ptr_reg->off + smin_val))) {
  			/* pointer += K.  Accumulate it into fixed offset */
  			dst_reg->smin_value = smin_ptr;
  			dst_reg->smax_value = smax_ptr;
  			dst_reg->umin_value = umin_ptr;
  			dst_reg->umax_value = umax_ptr;
  			dst_reg->var_off = ptr_reg->var_off;
  			dst_reg->off = ptr_reg->off + smin_val;
  			dst_reg->raw = ptr_reg->raw;
  			break;
  		}
  		/* A new variable offset is created.  Note that off_reg->off
  		 * == 0, since it's a scalar.
  		 * dst_reg gets the pointer type and since some positive
  		 * integer value was added to the pointer, give it a new 'id'
  		 * if it's a PTR_TO_PACKET.
  		 * this creates a new 'base' pointer, off_reg (variable) gets
  		 * added into the variable offset, and we copy the fixed offset
  		 * from ptr_reg.
  		 */
  		if (signed_add_overflows(smin_ptr, smin_val) ||
  		    signed_add_overflows(smax_ptr, smax_val)) {
  			dst_reg->smin_value = S64_MIN;
  			dst_reg->smax_value = S64_MAX;
  		} else {
  			dst_reg->smin_value = smin_ptr + smin_val;
  			dst_reg->smax_value = smax_ptr + smax_val;
  		}
  		if (umin_ptr + umin_val < umin_ptr ||
  		    umax_ptr + umax_val < umax_ptr) {
  			dst_reg->umin_value = 0;
  			dst_reg->umax_value = U64_MAX;
  		} else {
  			dst_reg->umin_value = umin_ptr + umin_val;
  			dst_reg->umax_value = umax_ptr + umax_val;
  		}
  		dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off);
  		dst_reg->off = ptr_reg->off;
  		dst_reg->raw = ptr_reg->raw;
  		if (reg_is_pkt_pointer(ptr_reg)) {
  			dst_reg->id = ++env->id_gen;
  			/* something was added to pkt_ptr, set range to zero */
  			memset(&dst_reg->raw, 0, sizeof(dst_reg->raw));
  		}
  		break;
  	case BPF_SUB:
  		if (dst_reg == off_reg) {
  			/* scalar -= pointer.  Creates an unknown scalar */
  			verbose(env, "R%d tried to subtract pointer from scalar\n",
  				dst);
  			return -EACCES;
  		}
  		/* We don't allow subtraction from FP, because (according to
  		 * test_verifier.c test "invalid fp arithmetic", JITs might not
  		 * be able to deal with it.
  		 */
  		if (ptr_reg->type == PTR_TO_STACK) {
  			verbose(env, "R%d subtraction from stack pointer prohibited\n",
  				dst);
  			return -EACCES;
  		}
  		if (known && (ptr_reg->off - smin_val ==
  			      (s64)(s32)(ptr_reg->off - smin_val))) {
  			/* pointer -= K.  Subtract it from fixed offset */
  			dst_reg->smin_value = smin_ptr;
  			dst_reg->smax_value = smax_ptr;
  			dst_reg->umin_value = umin_ptr;
  			dst_reg->umax_value = umax_ptr;
  			dst_reg->var_off = ptr_reg->var_off;
  			dst_reg->id = ptr_reg->id;
  			dst_reg->off = ptr_reg->off - smin_val;
  			dst_reg->raw = ptr_reg->raw;
  			break;
  		}
  		/* A new variable offset is created.  If the subtrahend is known
  		 * nonnegative, then any reg->range we had before is still good.
  		 */
  		if (signed_sub_overflows(smin_ptr, smax_val) ||
  		    signed_sub_overflows(smax_ptr, smin_val)) {
  			/* Overflow possible, we know nothing */
  			dst_reg->smin_value = S64_MIN;
  			dst_reg->smax_value = S64_MAX;
  		} else {
  			dst_reg->smin_value = smin_ptr - smax_val;
  			dst_reg->smax_value = smax_ptr - smin_val;
  		}
  		if (umin_ptr < umax_val) {
  			/* Overflow possible, we know nothing */
  			dst_reg->umin_value = 0;
  			dst_reg->umax_value = U64_MAX;
  		} else {
  			/* Cannot overflow (as long as bounds are consistent) */
  			dst_reg->umin_value = umin_ptr - umax_val;
  			dst_reg->umax_value = umax_ptr - umin_val;
  		}
  		dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off);
  		dst_reg->off = ptr_reg->off;
  		dst_reg->raw = ptr_reg->raw;
  		if (reg_is_pkt_pointer(ptr_reg)) {
  			dst_reg->id = ++env->id_gen;
  			/* something was added to pkt_ptr, set range to zero */
  			if (smin_val < 0)
  				memset(&dst_reg->raw, 0, sizeof(dst_reg->raw));
  		}
  		break;
  	case BPF_AND:
  	case BPF_OR:
  	case BPF_XOR:
  		/* bitwise ops on pointers are troublesome, prohibit. */
  		verbose(env, "R%d bitwise operator %s on pointer prohibited\n",
  			dst, bpf_alu_string[opcode >> 4]);
  		return -EACCES;
  	default:
  		/* other operators (e.g. MUL,LSH) produce non-pointer results */
  		verbose(env, "R%d pointer arithmetic with %s operator prohibited\n",
  			dst, bpf_alu_string[opcode >> 4]);
  		return -EACCES;
  	}
  
  	if (!check_reg_sane_offset(env, dst_reg, ptr_reg->type))
  		return -EINVAL;
  
  	__update_reg_bounds(dst_reg);
  	__reg_deduce_bounds(dst_reg);
  	__reg_bound_offset(dst_reg);
  
  	if (sanitize_check_bounds(env, insn, dst_reg) < 0)
  		return -EACCES;
  	if (sanitize_needed(opcode)) {
  		ret = sanitize_ptr_alu(env, insn, dst_reg, off_reg, dst_reg,
  				       &info, true);
  		if (ret < 0)
  			return sanitize_err(env, insn, ret, off_reg, dst_reg);
  	}
  
  	return 0;
  }
  
  static void scalar32_min_max_add(struct bpf_reg_state *dst_reg,
  				 struct bpf_reg_state *src_reg)
  {
  	s32 smin_val = src_reg->s32_min_value;
  	s32 smax_val = src_reg->s32_max_value;
  	u32 umin_val = src_reg->u32_min_value;
  	u32 umax_val = src_reg->u32_max_value;
  
  	if (signed_add32_overflows(dst_reg->s32_min_value, smin_val) ||
  	    signed_add32_overflows(dst_reg->s32_max_value, smax_val)) {
  		dst_reg->s32_min_value = S32_MIN;
  		dst_reg->s32_max_value = S32_MAX;
  	} else {
  		dst_reg->s32_min_value += smin_val;
  		dst_reg->s32_max_value += smax_val;
  	}
  	if (dst_reg->u32_min_value + umin_val < umin_val ||
  	    dst_reg->u32_max_value + umax_val < umax_val) {
  		dst_reg->u32_min_value = 0;
  		dst_reg->u32_max_value = U32_MAX;
  	} else {
  		dst_reg->u32_min_value += umin_val;
  		dst_reg->u32_max_value += umax_val;
  	}
  }
  
  static void scalar_min_max_add(struct bpf_reg_state *dst_reg,
  			       struct bpf_reg_state *src_reg)
  {
  	s64 smin_val = src_reg->smin_value;
  	s64 smax_val = src_reg->smax_value;
  	u64 umin_val = src_reg->umin_value;
  	u64 umax_val = src_reg->umax_value;
  
  	if (signed_add_overflows(dst_reg->smin_value, smin_val) ||
  	    signed_add_overflows(dst_reg->smax_value, smax_val)) {
  		dst_reg->smin_value = S64_MIN;
  		dst_reg->smax_value = S64_MAX;
  	} else {
  		dst_reg->smin_value += smin_val;
  		dst_reg->smax_value += smax_val;
  	}
  	if (dst_reg->umin_value + umin_val < umin_val ||
  	    dst_reg->umax_value + umax_val < umax_val) {
  		dst_reg->umin_value = 0;
  		dst_reg->umax_value = U64_MAX;
  	} else {
  		dst_reg->umin_value += umin_val;
  		dst_reg->umax_value += umax_val;
  	}
  }
  
  static void scalar32_min_max_sub(struct bpf_reg_state *dst_reg,
  				 struct bpf_reg_state *src_reg)
  {
  	s32 smin_val = src_reg->s32_min_value;
  	s32 smax_val = src_reg->s32_max_value;
  	u32 umin_val = src_reg->u32_min_value;
  	u32 umax_val = src_reg->u32_max_value;
  
  	if (signed_sub32_overflows(dst_reg->s32_min_value, smax_val) ||
  	    signed_sub32_overflows(dst_reg->s32_max_value, smin_val)) {
  		/* Overflow possible, we know nothing */
  		dst_reg->s32_min_value = S32_MIN;
  		dst_reg->s32_max_value = S32_MAX;
  	} else {
  		dst_reg->s32_min_value -= smax_val;
  		dst_reg->s32_max_value -= smin_val;
  	}
  	if (dst_reg->u32_min_value < umax_val) {
  		/* Overflow possible, we know nothing */
  		dst_reg->u32_min_value = 0;
  		dst_reg->u32_max_value = U32_MAX;
  	} else {
  		/* Cannot overflow (as long as bounds are consistent) */
  		dst_reg->u32_min_value -= umax_val;
  		dst_reg->u32_max_value -= umin_val;
  	}
  }
  
  static void scalar_min_max_sub(struct bpf_reg_state *dst_reg,
  			       struct bpf_reg_state *src_reg)
  {
  	s64 smin_val = src_reg->smin_value;
  	s64 smax_val = src_reg->smax_value;
  	u64 umin_val = src_reg->umin_value;
  	u64 umax_val = src_reg->umax_value;
  
  	if (signed_sub_overflows(dst_reg->smin_value, smax_val) ||
  	    signed_sub_overflows(dst_reg->smax_value, smin_val)) {
  		/* Overflow possible, we know nothing */
  		dst_reg->smin_value = S64_MIN;
  		dst_reg->smax_value = S64_MAX;
  	} else {
  		dst_reg->smin_value -= smax_val;
  		dst_reg->smax_value -= smin_val;
  	}
  	if (dst_reg->umin_value < umax_val) {
  		/* Overflow possible, we know nothing */
  		dst_reg->umin_value = 0;
  		dst_reg->umax_value = U64_MAX;
  	} else {
  		/* Cannot overflow (as long as bounds are consistent) */
  		dst_reg->umin_value -= umax_val;
  		dst_reg->umax_value -= umin_val;
  	}
  }
  
  static void scalar32_min_max_mul(struct bpf_reg_state *dst_reg,
  				 struct bpf_reg_state *src_reg)
  {
  	s32 smin_val = src_reg->s32_min_value;
  	u32 umin_val = src_reg->u32_min_value;
  	u32 umax_val = src_reg->u32_max_value;
  
  	if (smin_val < 0 || dst_reg->s32_min_value < 0) {
  		/* Ain't nobody got time to multiply that sign */
  		__mark_reg32_unbounded(dst_reg);
  		return;
  	}
  	/* Both values are positive, so we can work with unsigned and
  	 * copy the result to signed (unless it exceeds S32_MAX).
  	 */
  	if (umax_val > U16_MAX || dst_reg->u32_max_value > U16_MAX) {
  		/* Potential overflow, we know nothing */
  		__mark_reg32_unbounded(dst_reg);
  		return;
  	}
  	dst_reg->u32_min_value *= umin_val;
  	dst_reg->u32_max_value *= umax_val;
  	if (dst_reg->u32_max_value > S32_MAX) {
  		/* Overflow possible, we know nothing */
  		dst_reg->s32_min_value = S32_MIN;
  		dst_reg->s32_max_value = S32_MAX;
  	} else {
  		dst_reg->s32_min_value = dst_reg->u32_min_value;
  		dst_reg->s32_max_value = dst_reg->u32_max_value;
  	}
  }
  
  static void scalar_min_max_mul(struct bpf_reg_state *dst_reg,
  			       struct bpf_reg_state *src_reg)
  {
  	s64 smin_val = src_reg->smin_value;
  	u64 umin_val = src_reg->umin_value;
  	u64 umax_val = src_reg->umax_value;
  
  	if (smin_val < 0 || dst_reg->smin_value < 0) {
  		/* Ain't nobody got time to multiply that sign */
  		__mark_reg64_unbounded(dst_reg);
  		return;
  	}
  	/* Both values are positive, so we can work with unsigned and
  	 * copy the result to signed (unless it exceeds S64_MAX).
  	 */
  	if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) {
  		/* Potential overflow, we know nothing */
  		__mark_reg64_unbounded(dst_reg);
  		return;
  	}
  	dst_reg->umin_value *= umin_val;
  	dst_reg->umax_value *= umax_val;
  	if (dst_reg->umax_value > S64_MAX) {
  		/* Overflow possible, we know nothing */
  		dst_reg->smin_value = S64_MIN;
  		dst_reg->smax_value = S64_MAX;
  	} else {
  		dst_reg->smin_value = dst_reg->umin_value;
  		dst_reg->smax_value = dst_reg->umax_value;
  	}
  }
  
  static void scalar32_min_max_and(struct bpf_reg_state *dst_reg,
  				 struct bpf_reg_state *src_reg)
  {
  	bool src_known = tnum_subreg_is_const(src_reg->var_off);
  	bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
  	struct tnum var32_off = tnum_subreg(dst_reg->var_off);
  	s32 smin_val = src_reg->s32_min_value;
  	u32 umax_val = src_reg->u32_max_value;
  
  	if (src_known && dst_known) {
  		__mark_reg32_known(dst_reg, var32_off.value);
  		return;
  	}
  
  	/* We get our minimum from the var_off, since that's inherently
  	 * bitwise.  Our maximum is the minimum of the operands' maxima.
  	 */
  	dst_reg->u32_min_value = var32_off.value;
  	dst_reg->u32_max_value = min(dst_reg->u32_max_value, umax_val);
  	if (dst_reg->s32_min_value < 0 || smin_val < 0) {
  		/* Lose signed bounds when ANDing negative numbers,
  		 * ain't nobody got time for that.
  		 */
  		dst_reg->s32_min_value = S32_MIN;
  		dst_reg->s32_max_value = S32_MAX;
  	} else {
  		/* ANDing two positives gives a positive, so safe to
  		 * cast result into s64.
  		 */
  		dst_reg->s32_min_value = dst_reg->u32_min_value;
  		dst_reg->s32_max_value = dst_reg->u32_max_value;
  	}
  }
  
  static void scalar_min_max_and(struct bpf_reg_state *dst_reg,
  			       struct bpf_reg_state *src_reg)
  {
  	bool src_known = tnum_is_const(src_reg->var_off);
  	bool dst_known = tnum_is_const(dst_reg->var_off);
  	s64 smin_val = src_reg->smin_value;
  	u64 umax_val = src_reg->umax_value;
  
  	if (src_known && dst_known) {
  		__mark_reg_known(dst_reg, dst_reg->var_off.value);
  		return;
  	}
  
  	/* We get our minimum from the var_off, since that's inherently
  	 * bitwise.  Our maximum is the minimum of the operands' maxima.
  	 */
  	dst_reg->umin_value = dst_reg->var_off.value;
  	dst_reg->umax_value = min(dst_reg->umax_value, umax_val);
  	if (dst_reg->smin_value < 0 || smin_val < 0) {
  		/* Lose signed bounds when ANDing negative numbers,
  		 * ain't nobody got time for that.
  		 */
  		dst_reg->smin_value = S64_MIN;
  		dst_reg->smax_value = S64_MAX;
  	} else {
  		/* ANDing two positives gives a positive, so safe to
  		 * cast result into s64.
  		 */
  		dst_reg->smin_value = dst_reg->umin_value;
  		dst_reg->smax_value = dst_reg->umax_value;
  	}
  	/* We may learn something more from the var_off */
  	__update_reg_bounds(dst_reg);
  }
  
  static void scalar32_min_max_or(struct bpf_reg_state *dst_reg,
  				struct bpf_reg_state *src_reg)
  {
  	bool src_known = tnum_subreg_is_const(src_reg->var_off);
  	bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
  	struct tnum var32_off = tnum_subreg(dst_reg->var_off);
  	s32 smin_val = src_reg->s32_min_value;
  	u32 umin_val = src_reg->u32_min_value;
  
  	if (src_known && dst_known) {
  		__mark_reg32_known(dst_reg, var32_off.value);
  		return;
  	}
  
  	/* We get our maximum from the var_off, and our minimum is the
  	 * maximum of the operands' minima
  	 */
  	dst_reg->u32_min_value = max(dst_reg->u32_min_value, umin_val);
  	dst_reg->u32_max_value = var32_off.value | var32_off.mask;
  	if (dst_reg->s32_min_value < 0 || smin_val < 0) {
  		/* Lose signed bounds when ORing negative numbers,
  		 * ain't nobody got time for that.
  		 */
  		dst_reg->s32_min_value = S32_MIN;
  		dst_reg->s32_max_value = S32_MAX;
  	} else {
  		/* ORing two positives gives a positive, so safe to
  		 * cast result into s64.
  		 */
  		dst_reg->s32_min_value = dst_reg->u32_min_value;
  		dst_reg->s32_max_value = dst_reg->u32_max_value;
  	}
  }
  
  static void scalar_min_max_or(struct bpf_reg_state *dst_reg,
  			      struct bpf_reg_state *src_reg)
  {
  	bool src_known = tnum_is_const(src_reg->var_off);
  	bool dst_known = tnum_is_const(dst_reg->var_off);
  	s64 smin_val = src_reg->smin_value;
  	u64 umin_val = src_reg->umin_value;
  
  	if (src_known && dst_known) {
  		__mark_reg_known(dst_reg, dst_reg->var_off.value);
  		return;
  	}
  
  	/* We get our maximum from the var_off, and our minimum is the
  	 * maximum of the operands' minima
  	 */
  	dst_reg->umin_value = max(dst_reg->umin_value, umin_val);
  	dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;
  	if (dst_reg->smin_value < 0 || smin_val < 0) {
  		/* Lose signed bounds when ORing negative numbers,
  		 * ain't nobody got time for that.
  		 */
  		dst_reg->smin_value = S64_MIN;
  		dst_reg->smax_value = S64_MAX;
  	} else {
  		/* ORing two positives gives a positive, so safe to
  		 * cast result into s64.
  		 */
  		dst_reg->smin_value = dst_reg->umin_value;
  		dst_reg->smax_value = dst_reg->umax_value;
  	}
  	/* We may learn something more from the var_off */
  	__update_reg_bounds(dst_reg);
  }
  
  static void scalar32_min_max_xor(struct bpf_reg_state *dst_reg,
  				 struct bpf_reg_state *src_reg)
  {
  	bool src_known = tnum_subreg_is_const(src_reg->var_off);
  	bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
  	struct tnum var32_off = tnum_subreg(dst_reg->var_off);
  	s32 smin_val = src_reg->s32_min_value;
  
  	if (src_known && dst_known) {
  		__mark_reg32_known(dst_reg, var32_off.value);
  		return;
  	}
  
  	/* We get both minimum and maximum from the var32_off. */
  	dst_reg->u32_min_value = var32_off.value;
  	dst_reg->u32_max_value = var32_off.value | var32_off.mask;
  
  	if (dst_reg->s32_min_value >= 0 && smin_val >= 0) {
  		/* XORing two positive sign numbers gives a positive,
  		 * so safe to cast u32 result into s32.
  		 */
  		dst_reg->s32_min_value = dst_reg->u32_min_value;
  		dst_reg->s32_max_value = dst_reg->u32_max_value;
  	} else {
  		dst_reg->s32_min_value = S32_MIN;
  		dst_reg->s32_max_value = S32_MAX;
  	}
  }
  
  static void scalar_min_max_xor(struct bpf_reg_state *dst_reg,
  			       struct bpf_reg_state *src_reg)
  {
  	bool src_known = tnum_is_const(src_reg->var_off);
  	bool dst_known = tnum_is_const(dst_reg->var_off);
  	s64 smin_val = src_reg->smin_value;
  
  	if (src_known && dst_known) {
  		/* dst_reg->var_off.value has been updated earlier */
  		__mark_reg_known(dst_reg, dst_reg->var_off.value);
  		return;
  	}
  
  	/* We get both minimum and maximum from the var_off. */
  	dst_reg->umin_value = dst_reg->var_off.value;
  	dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;
  
  	if (dst_reg->smin_value >= 0 && smin_val >= 0) {
  		/* XORing two positive sign numbers gives a positive,
  		 * so safe to cast u64 result into s64.
  		 */
  		dst_reg->smin_value = dst_reg->umin_value;
  		dst_reg->smax_value = dst_reg->umax_value;
  	} else {
  		dst_reg->smin_value = S64_MIN;
  		dst_reg->smax_value = S64_MAX;
  	}
  
  	__update_reg_bounds(dst_reg);
  }
  
  static void __scalar32_min_max_lsh(struct bpf_reg_state *dst_reg,
  				   u64 umin_val, u64 umax_val)
  {
  	/* We lose all sign bit information (except what we can pick
  	 * up from var_off)
  	 */
  	dst_reg->s32_min_value = S32_MIN;
  	dst_reg->s32_max_value = S32_MAX;
  	/* If we might shift our top bit out, then we know nothing */
  	if (umax_val > 31 || dst_reg->u32_max_value > 1ULL << (31 - umax_val)) {
  		dst_reg->u32_min_value = 0;
  		dst_reg->u32_max_value = U32_MAX;
  	} else {
  		dst_reg->u32_min_value <<= umin_val;
  		dst_reg->u32_max_value <<= umax_val;
  	}
  }
  
  static void scalar32_min_max_lsh(struct bpf_reg_state *dst_reg,
  				 struct bpf_reg_state *src_reg)
  {
  	u32 umax_val = src_reg->u32_max_value;
  	u32 umin_val = src_reg->u32_min_value;
  	/* u32 alu operation will zext upper bits */
  	struct tnum subreg = tnum_subreg(dst_reg->var_off);
  
  	__scalar32_min_max_lsh(dst_reg, umin_val, umax_val);
  	dst_reg->var_off = tnum_subreg(tnum_lshift(subreg, umin_val));
  	/* Not required but being careful mark reg64 bounds as unknown so
  	 * that we are forced to pick them up from tnum and zext later and
  	 * if some path skips this step we are still safe.
  	 */
  	__mark_reg64_unbounded(dst_reg);
  	__update_reg32_bounds(dst_reg);
  }
  
  static void __scalar64_min_max_lsh(struct bpf_reg_state *dst_reg,
  				   u64 umin_val, u64 umax_val)
  {
  	/* Special case <<32 because it is a common compiler pattern to sign
  	 * extend subreg by doing <<32 s>>32. In this case if 32bit bounds are
  	 * positive we know this shift will also be positive so we can track
  	 * bounds correctly. Otherwise we lose all sign bit information except
  	 * what we can pick up from var_off. Perhaps we can generalize this
  	 * later to shifts of any length.
  	 */
  	if (umin_val == 32 && umax_val == 32 && dst_reg->s32_max_value >= 0)
  		dst_reg->smax_value = (s64)dst_reg->s32_max_value << 32;
  	else
  		dst_reg->smax_value = S64_MAX;
  
  	if (umin_val == 32 && umax_val == 32 && dst_reg->s32_min_value >= 0)
  		dst_reg->smin_value = (s64)dst_reg->s32_min_value << 32;
  	else
  		dst_reg->smin_value = S64_MIN;
  
  	/* If we might shift our top bit out, then we know nothing */
  	if (dst_reg->umax_value > 1ULL << (63 - umax_val)) {
  		dst_reg->umin_value = 0;
  		dst_reg->umax_value = U64_MAX;
  	} else {
  		dst_reg->umin_value <<= umin_val;
  		dst_reg->umax_value <<= umax_val;
  	}
  }
  
  static void scalar_min_max_lsh(struct bpf_reg_state *dst_reg,
  			       struct bpf_reg_state *src_reg)
  {
  	u64 umax_val = src_reg->umax_value;
  	u64 umin_val = src_reg->umin_value;
  
  	/* scalar64 calc uses 32bit unshifted bounds so must be called first */
  	__scalar64_min_max_lsh(dst_reg, umin_val, umax_val);
  	__scalar32_min_max_lsh(dst_reg, umin_val, umax_val);
  
  	dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);
  	/* We may learn something more from the var_off */
  	__update_reg_bounds(dst_reg);
  }
  
  static void scalar32_min_max_rsh(struct bpf_reg_state *dst_reg,
  				 struct bpf_reg_state *src_reg)
  {
  	struct tnum subreg = tnum_subreg(dst_reg->var_off);
  	u32 umax_val = src_reg->u32_max_value;
  	u32 umin_val = src_reg->u32_min_value;
  
  	/* BPF_RSH is an unsigned shift.  If the value in dst_reg might
  	 * be negative, then either:
  	 * 1) src_reg might be zero, so the sign bit of the result is
  	 *    unknown, so we lose our signed bounds
  	 * 2) it's known negative, thus the unsigned bounds capture the
  	 *    signed bounds
  	 * 3) the signed bounds cross zero, so they tell us nothing
  	 *    about the result
  	 * If the value in dst_reg is known nonnegative, then again the
  	 * unsigned bounds capture the signed bounds.
  	 * Thus, in all cases it suffices to blow away our signed bounds
  	 * and rely on inferring new ones from the unsigned bounds and
  	 * var_off of the result.
  	 */
  	dst_reg->s32_min_value = S32_MIN;
  	dst_reg->s32_max_value = S32_MAX;
  
  	dst_reg->var_off = tnum_rshift(subreg, umin_val);
  	dst_reg->u32_min_value >>= umax_val;
  	dst_reg->u32_max_value >>= umin_val;
  
  	__mark_reg64_unbounded(dst_reg);
  	__update_reg32_bounds(dst_reg);
  }
  
  static void scalar_min_max_rsh(struct bpf_reg_state *dst_reg,
  			       struct bpf_reg_state *src_reg)
  {
  	u64 umax_val = src_reg->umax_value;
  	u64 umin_val = src_reg->umin_value;
  
  	/* BPF_RSH is an unsigned shift.  If the value in dst_reg might
  	 * be negative, then either:
  	 * 1) src_reg might be zero, so the sign bit of the result is
  	 *    unknown, so we lose our signed bounds
  	 * 2) it's known negative, thus the unsigned bounds capture the
  	 *    signed bounds
  	 * 3) the signed bounds cross zero, so they tell us nothing
  	 *    about the result
  	 * If the value in dst_reg is known nonnegative, then again the
  	 * unsigned bounds capture the signed bounds.
  	 * Thus, in all cases it suffices to blow away our signed bounds
  	 * and rely on inferring new ones from the unsigned bounds and
  	 * var_off of the result.
  	 */
  	dst_reg->smin_value = S64_MIN;
  	dst_reg->smax_value = S64_MAX;
  	dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val);
  	dst_reg->umin_value >>= umax_val;
  	dst_reg->umax_value >>= umin_val;
  
  	/* Its not easy to operate on alu32 bounds here because it depends
  	 * on bits being shifted in. Take easy way out and mark unbounded
  	 * so we can recalculate later from tnum.
  	 */
  	__mark_reg32_unbounded(dst_reg);
  	__update_reg_bounds(dst_reg);
  }
  
  static void scalar32_min_max_arsh(struct bpf_reg_state *dst_reg,
  				  struct bpf_reg_state *src_reg)
  {
  	u64 umin_val = src_reg->u32_min_value;
  
  	/* Upon reaching here, src_known is true and
  	 * umax_val is equal to umin_val.
  	 */
  	dst_reg->s32_min_value = (u32)(((s32)dst_reg->s32_min_value) >> umin_val);
  	dst_reg->s32_max_value = (u32)(((s32)dst_reg->s32_max_value) >> umin_val);
  
  	dst_reg->var_off = tnum_arshift(tnum_subreg(dst_reg->var_off), umin_val, 32);
  
  	/* blow away the dst_reg umin_value/umax_value and rely on
  	 * dst_reg var_off to refine the result.
  	 */
  	dst_reg->u32_min_value = 0;
  	dst_reg->u32_max_value = U32_MAX;
  
  	__mark_reg64_unbounded(dst_reg);
  	__update_reg32_bounds(dst_reg);
  }
  
  static void scalar_min_max_arsh(struct bpf_reg_state *dst_reg,
  				struct bpf_reg_state *src_reg)
  {
  	u64 umin_val = src_reg->umin_value;
  
  	/* Upon reaching here, src_known is true and umax_val is equal
  	 * to umin_val.
  	 */
  	dst_reg->smin_value >>= umin_val;
  	dst_reg->smax_value >>= umin_val;
  
  	dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val, 64);
  
  	/* blow away the dst_reg umin_value/umax_value and rely on
  	 * dst_reg var_off to refine the result.
  	 */
  	dst_reg->umin_value = 0;
  	dst_reg->umax_value = U64_MAX;
  
  	/* Its not easy to operate on alu32 bounds here because it depends
  	 * on bits being shifted in from upper 32-bits. Take easy way out
  	 * and mark unbounded so we can recalculate later from tnum.
  	 */
  	__mark_reg32_unbounded(dst_reg);
  	__update_reg_bounds(dst_reg);
  }
  
  /* WARNING: This function does calculations on 64-bit values, but the actual
   * execution may occur on 32-bit values. Therefore, things like bitshifts
   * need extra checks in the 32-bit case.
   */
  static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
  				      struct bpf_insn *insn,
  				      struct bpf_reg_state *dst_reg,
  				      struct bpf_reg_state src_reg)
  {
  	struct bpf_reg_state *regs = cur_regs(env);
  	u8 opcode = BPF_OP(insn->code);
  	bool src_known;
  	s64 smin_val, smax_val;
  	u64 umin_val, umax_val;
  	s32 s32_min_val, s32_max_val;
  	u32 u32_min_val, u32_max_val;
  	u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32;
  	bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64);
  	int ret;
  
  	smin_val = src_reg.smin_value;
  	smax_val = src_reg.smax_value;
  	umin_val = src_reg.umin_value;
  	umax_val = src_reg.umax_value;
  
  	s32_min_val = src_reg.s32_min_value;
  	s32_max_val = src_reg.s32_max_value;
  	u32_min_val = src_reg.u32_min_value;
  	u32_max_val = src_reg.u32_max_value;
  
  	if (alu32) {
  		src_known = tnum_subreg_is_const(src_reg.var_off);
  		if ((src_known &&
  		     (s32_min_val != s32_max_val || u32_min_val != u32_max_val)) ||
  		    s32_min_val > s32_max_val || u32_min_val > u32_max_val) {
  			/* Taint dst register if offset had invalid bounds
  			 * derived from e.g. dead branches.
  			 */
  			__mark_reg_unknown(env, dst_reg);
  			return 0;
  		}
  	} else {
  		src_known = tnum_is_const(src_reg.var_off);
  		if ((src_known &&
  		     (smin_val != smax_val || umin_val != umax_val)) ||
  		    smin_val > smax_val || umin_val > umax_val) {
  			/* Taint dst register if offset had invalid bounds
  			 * derived from e.g. dead branches.
  			 */
  			__mark_reg_unknown(env, dst_reg);
  			return 0;
  		}
  	}
  
  	if (!src_known &&
  	    opcode != BPF_ADD && opcode != BPF_SUB && opcode != BPF_AND) {
  		__mark_reg_unknown(env, dst_reg);
  		return 0;
  	}
  
  	if (sanitize_needed(opcode)) {
  		ret = sanitize_val_alu(env, insn);
  		if (ret < 0)
  			return sanitize_err(env, insn, ret, NULL, NULL);
  	}
  
  	/* Calculate sign/unsigned bounds and tnum for alu32 and alu64 bit ops.
  	 * There are two classes of instructions: The first class we track both
  	 * alu32 and alu64 sign/unsigned bounds independently this provides the
  	 * greatest amount of precision when alu operations are mixed with jmp32
  	 * operations. These operations are BPF_ADD, BPF_SUB, BPF_MUL, BPF_ADD,
  	 * and BPF_OR. This is possible because these ops have fairly easy to
  	 * understand and calculate behavior in both 32-bit and 64-bit alu ops.
  	 * See alu32 verifier tests for examples. The second class of
  	 * operations, BPF_LSH, BPF_RSH, and BPF_ARSH, however are not so easy
  	 * with regards to tracking sign/unsigned bounds because the bits may
  	 * cross subreg boundaries in the alu64 case. When this happens we mark
  	 * the reg unbounded in the subreg bound space and use the resulting
  	 * tnum to calculate an approximation of the sign/unsigned bounds.
  	 */
  	switch (opcode) {
  	case BPF_ADD:
  		scalar32_min_max_add(dst_reg, &src_reg);
  		scalar_min_max_add(dst_reg, &src_reg);
  		dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
  		break;
  	case BPF_SUB:
  		scalar32_min_max_sub(dst_reg, &src_reg);
  		scalar_min_max_sub(dst_reg, &src_reg);
  		dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off);
  		break;
  	case BPF_MUL:
  		dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off);
  		scalar32_min_max_mul(dst_reg, &src_reg);
  		scalar_min_max_mul(dst_reg, &src_reg);
  		break;
  	case BPF_AND:
  		dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off);
  		scalar32_min_max_and(dst_reg, &src_reg);
  		scalar_min_max_and(dst_reg, &src_reg);
  		break;
  	case BPF_OR:
  		dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off);
  		scalar32_min_max_or(dst_reg, &src_reg);
  		scalar_min_max_or(dst_reg, &src_reg);
  		break;
  	case BPF_XOR:
  		dst_reg->var_off = tnum_xor(dst_reg->var_off, src_reg.var_off);
  		scalar32_min_max_xor(dst_reg, &src_reg);
  		scalar_min_max_xor(dst_reg, &src_reg);
  		break;
  	case BPF_LSH:
  		if (umax_val >= insn_bitness) {
  			/* Shifts greater than 31 or 63 are undefined.
  			 * This includes shifts by a negative number.
  			 */
  			mark_reg_unknown(env, regs, insn->dst_reg);
  			break;
  		}
  		if (alu32)
  			scalar32_min_max_lsh(dst_reg, &src_reg);
  		else
  			scalar_min_max_lsh(dst_reg, &src_reg);
  		break;
  	case BPF_RSH:
  		if (umax_val >= insn_bitness) {
  			/* Shifts greater than 31 or 63 are undefined.
  			 * This includes shifts by a negative number.
  			 */
  			mark_reg_unknown(env, regs, insn->dst_reg);
  			break;
  		}
  		if (alu32)
  			scalar32_min_max_rsh(dst_reg, &src_reg);
  		else
  			scalar_min_max_rsh(dst_reg, &src_reg);
  		break;
  	case BPF_ARSH:
  		if (umax_val >= insn_bitness) {
  			/* Shifts greater than 31 or 63 are undefined.
  			 * This includes shifts by a negative number.
  			 */
  			mark_reg_unknown(env, regs, insn->dst_reg);
  			break;
  		}
  		if (alu32)
  			scalar32_min_max_arsh(dst_reg, &src_reg);
  		else
  			scalar_min_max_arsh(dst_reg, &src_reg);
  		break;
  	default:
  		mark_reg_unknown(env, regs, insn->dst_reg);
  		break;
  	}
  
  	/* ALU32 ops are zero extended into 64bit register */
  	if (alu32)
  		zext_32_to_64(dst_reg);
  
  	__update_reg_bounds(dst_reg);
  	__reg_deduce_bounds(dst_reg);
  	__reg_bound_offset(dst_reg);
  	return 0;
  }
  
  /* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max
   * and var_off.
   */
  static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
  				   struct bpf_insn *insn)
  {
  	struct bpf_verifier_state *vstate = env->cur_state;
  	struct bpf_func_state *state = vstate->frame[vstate->curframe];
  	struct bpf_reg_state *regs = state->regs, *dst_reg, *src_reg;
  	struct bpf_reg_state *ptr_reg = NULL, off_reg = {0};
  	u8 opcode = BPF_OP(insn->code);
  	int err;
  
  	dst_reg = &regs[insn->dst_reg];
  	src_reg = NULL;
  	if (dst_reg->type != SCALAR_VALUE)
  		ptr_reg = dst_reg;
  	else
  		/* Make sure ID is cleared otherwise dst_reg min/max could be
  		 * incorrectly propagated into other registers by find_equal_scalars()
  		 */
  		dst_reg->id = 0;
  	if (BPF_SRC(insn->code) == BPF_X) {
  		src_reg = &regs[insn->src_reg];
  		if (src_reg->type != SCALAR_VALUE) {
  			if (dst_reg->type != SCALAR_VALUE) {
  				/* Combining two pointers by any ALU op yields
  				 * an arbitrary scalar. Disallow all math except
  				 * pointer subtraction
  				 */
  				if (opcode == BPF_SUB && env->allow_ptr_leaks) {
  					mark_reg_unknown(env, regs, insn->dst_reg);
  					return 0;
  				}
  				verbose(env, "R%d pointer %s pointer prohibited\n",
  					insn->dst_reg,
  					bpf_alu_string[opcode >> 4]);
  				return -EACCES;
  			} else {
  				/* scalar += pointer
  				 * This is legal, but we have to reverse our
  				 * src/dest handling in computing the range
  				 */
  				err = mark_chain_precision(env, insn->dst_reg);
  				if (err)
  					return err;
  				return adjust_ptr_min_max_vals(env, insn,
  							       src_reg, dst_reg);
  			}
  		} else if (ptr_reg) {
  			/* pointer += scalar */
  			err = mark_chain_precision(env, insn->src_reg);
  			if (err)
  				return err;
  			return adjust_ptr_min_max_vals(env, insn,
  						       dst_reg, src_reg);
  		}
  	} else {
  		/* Pretend the src is a reg with a known value, since we only
  		 * need to be able to read from this state.
  		 */
  		off_reg.type = SCALAR_VALUE;
  		__mark_reg_known(&off_reg, insn->imm);
  		src_reg = &off_reg;
  		if (ptr_reg) /* pointer += K */
  			return adjust_ptr_min_max_vals(env, insn,
  						       ptr_reg, src_reg);
  	}
  
  	/* Got here implies adding two SCALAR_VALUEs */
  	if (WARN_ON_ONCE(ptr_reg)) {
  		print_verifier_state(env, state, true);
  		verbose(env, "verifier internal error: unexpected ptr_reg\n");
  		return -EINVAL;
  	}
  	if (WARN_ON(!src_reg)) {
  		print_verifier_state(env, state, true);
  		verbose(env, "verifier internal error: no src_reg\n");
  		return -EINVAL;
  	}
  	return adjust_scalar_min_max_vals(env, insn, dst_reg, *src_reg);
  }
  
  /* check validity of 32-bit and 64-bit arithmetic operations */
  static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
  {
  	struct bpf_reg_state *regs = cur_regs(env);
  	u8 opcode = BPF_OP(insn->code);
  	int err;
  
  	if (opcode == BPF_END || opcode == BPF_NEG) {
  		if (opcode == BPF_NEG) {
  			if (BPF_SRC(insn->code) != 0 ||
  			    insn->src_reg != BPF_REG_0 ||
  			    insn->off != 0 || insn->imm != 0) {
  				verbose(env, "BPF_NEG uses reserved fields\n");
  				return -EINVAL;
  			}
  		} else {
  			if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
  			    (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) ||
  			    BPF_CLASS(insn->code) == BPF_ALU64) {
  				verbose(env, "BPF_END uses reserved fields\n");
  				return -EINVAL;
  			}
  		}
  
  		/* check src operand */
  		err = check_reg_arg(env, insn->dst_reg, SRC_OP);
  		if (err)
  			return err;
  
  		if (is_pointer_value(env, insn->dst_reg)) {
  			verbose(env, "R%d pointer arithmetic prohibited\n",
  				insn->dst_reg);
  			return -EACCES;
  		}
  
  		/* check dest operand */
  		err = check_reg_arg(env, insn->dst_reg, DST_OP);
  		if (err)
  			return err;
  
  	} else if (opcode == BPF_MOV) {
  
  		if (BPF_SRC(insn->code) == BPF_X) {
  			if (insn->imm != 0 || insn->off != 0) {
  				verbose(env, "BPF_MOV uses reserved fields\n");
  				return -EINVAL;
  			}
  
  			/* check src operand */
  			err = check_reg_arg(env, insn->src_reg, SRC_OP);
  			if (err)
  				return err;
  		} else {
  			if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
  				verbose(env, "BPF_MOV uses reserved fields\n");
  				return -EINVAL;
  			}
  		}
  
  		/* check dest operand, mark as required later */
  		err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
  		if (err)
  			return err;
  
  		if (BPF_SRC(insn->code) == BPF_X) {
  			struct bpf_reg_state *src_reg = regs + insn->src_reg;
  			struct bpf_reg_state *dst_reg = regs + insn->dst_reg;
  
  			if (BPF_CLASS(insn->code) == BPF_ALU64) {
  				/* case: R1 = R2
  				 * copy register state to dest reg
  				 */
  				if (src_reg->type == SCALAR_VALUE && !src_reg->id)
  					/* Assign src and dst registers the same ID
  					 * that will be used by find_equal_scalars()
  					 * to propagate min/max range.
  					 */
  					src_reg->id = ++env->id_gen;
  				*dst_reg = *src_reg;
  				dst_reg->live |= REG_LIVE_WRITTEN;
  				dst_reg->subreg_def = DEF_NOT_SUBREG;
  			} else {
  				/* R1 = (u32) R2 */
  				if (is_pointer_value(env, insn->src_reg)) {
  					verbose(env,
  						"R%d partial copy of pointer\n",
  						insn->src_reg);
  					return -EACCES;
  				} else if (src_reg->type == SCALAR_VALUE) {
  					*dst_reg = *src_reg;
  					/* Make sure ID is cleared otherwise
  					 * dst_reg min/max could be incorrectly
  					 * propagated into src_reg by find_equal_scalars()
  					 */
  					dst_reg->id = 0;
  					dst_reg->live |= REG_LIVE_WRITTEN;
  					dst_reg->subreg_def = env->insn_idx + 1;
  				} else {
  					mark_reg_unknown(env, regs,
  							 insn->dst_reg);
  				}
  				zext_32_to_64(dst_reg);
  
  				__update_reg_bounds(dst_reg);
  				__reg_deduce_bounds(dst_reg);
  				__reg_bound_offset(dst_reg);
  			}
  		} else {
  			/* case: R = imm
  			 * remember the value we stored into this reg
  			 */
  			/* clear any state __mark_reg_known doesn't set */
  			mark_reg_unknown(env, regs, insn->dst_reg);
  			regs[insn->dst_reg].type = SCALAR_VALUE;
  			if (BPF_CLASS(insn->code) == BPF_ALU64) {
  				__mark_reg_known(regs + insn->dst_reg,
  						 insn->imm);
  			} else {
  				__mark_reg_known(regs + insn->dst_reg,
  						 (u32)insn->imm);
  			}
  		}
  
  	} else if (opcode > BPF_END) {
  		verbose(env, "invalid BPF_ALU opcode %x\n", opcode);
  		return -EINVAL;
  
  	} else {	/* all other ALU ops: and, sub, xor, add, ... */
  
  		if (BPF_SRC(insn->code) == BPF_X) {
  			if (insn->imm != 0 || insn->off != 0) {
  				verbose(env, "BPF_ALU uses reserved fields\n");
  				return -EINVAL;
  			}
  			/* check src1 operand */
  			err = check_reg_arg(env, insn->src_reg, SRC_OP);
  			if (err)
  				return err;
  		} else {
  			if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
  				verbose(env, "BPF_ALU uses reserved fields\n");
  				return -EINVAL;
  			}
  		}
  
  		/* check src2 operand */
  		err = check_reg_arg(env, insn->dst_reg, SRC_OP);
  		if (err)
  			return err;
  
  		if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
  		    BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
  			verbose(env, "div by zero\n");
  			return -EINVAL;
  		}
  
  		if ((opcode == BPF_LSH || opcode == BPF_RSH ||
  		     opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
  			int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;
  
  			if (insn->imm < 0 || insn->imm >= size) {
  				verbose(env, "invalid shift %d\n", insn->imm);
  				return -EINVAL;
  			}
  		}
  
  		/* check dest operand */
  		err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
  		if (err)
  			return err;
  
  		return adjust_reg_min_max_vals(env, insn);
  	}
  
  	return 0;
  }
  
  static void __find_good_pkt_pointers(struct bpf_func_state *state,
  				     struct bpf_reg_state *dst_reg,
  				     enum bpf_reg_type type, int new_range)
  {
  	struct bpf_reg_state *reg;
  	int i;
  
  	for (i = 0; i < MAX_BPF_REG; i++) {
  		reg = &state->regs[i];
  		if (reg->type == type && reg->id == dst_reg->id)
  			/* keep the maximum range already checked */
  			reg->range = max(reg->range, new_range);
  	}
  
  	bpf_for_each_spilled_reg(i, state, reg) {
  		if (!reg)
  			continue;
  		if (reg->type == type && reg->id == dst_reg->id)
  			reg->range = max(reg->range, new_range);
  	}
  }
  
  static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
  				   struct bpf_reg_state *dst_reg,
  				   enum bpf_reg_type type,
  				   bool range_right_open)
  {
  	int new_range, i;
  
  	if (dst_reg->off < 0 ||
  	    (dst_reg->off == 0 && range_right_open))
  		/* This doesn't give us any range */
  		return;
  
  	if (dst_reg->umax_value > MAX_PACKET_OFF ||
  	    dst_reg->umax_value + dst_reg->off > MAX_PACKET_OFF)
  		/* Risk of overflow.  For instance, ptr + (1<<63) may be less
  		 * than pkt_end, but that's because it's also less than pkt.
  		 */
  		return;
  
  	new_range = dst_reg->off;
  	if (range_right_open)
  		new_range++;
  
  	/* Examples for register markings:
  	 *
  	 * pkt_data in dst register:
  	 *
  	 *   r2 = r3;
  	 *   r2 += 8;
  	 *   if (r2 > pkt_end) goto <handle exception>
  	 *   <access okay>
  	 *
  	 *   r2 = r3;
  	 *   r2 += 8;
  	 *   if (r2 < pkt_end) goto <access okay>
  	 *   <handle exception>
  	 *
  	 *   Where:
  	 *     r2 == dst_reg, pkt_end == src_reg
  	 *     r2=pkt(id=n,off=8,r=0)
  	 *     r3=pkt(id=n,off=0,r=0)
  	 *
  	 * pkt_data in src register:
  	 *
  	 *   r2 = r3;
  	 *   r2 += 8;
  	 *   if (pkt_end >= r2) goto <access okay>
  	 *   <handle exception>
  	 *
  	 *   r2 = r3;
  	 *   r2 += 8;
  	 *   if (pkt_end <= r2) goto <handle exception>
  	 *   <access okay>
  	 *
  	 *   Where:
  	 *     pkt_end == dst_reg, r2 == src_reg
  	 *     r2=pkt(id=n,off=8,r=0)
  	 *     r3=pkt(id=n,off=0,r=0)
  	 *
  	 * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
  	 * or r3=pkt(id=n,off=0,r=8-1), so that range of bytes [r3, r3 + 8)
  	 * and [r3, r3 + 8-1) respectively is safe to access depending on
  	 * the check.
  	 */
  
  	/* If our ids match, then we must have the same max_value.  And we
  	 * don't care about the other reg's fixed offset, since if it's too big
  	 * the range won't allow anything.
  	 * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16.
  	 */
  	for (i = 0; i <= vstate->curframe; i++)
  		__find_good_pkt_pointers(vstate->frame[i], dst_reg, type,
  					 new_range);
  }
  
  static int is_branch32_taken(struct bpf_reg_state *reg, u32 val, u8 opcode)
  {
  	struct tnum subreg = tnum_subreg(reg->var_off);
  	s32 sval = (s32)val;
  
  	switch (opcode) {
  	case BPF_JEQ:
  		if (tnum_is_const(subreg))
  			return !!tnum_equals_const(subreg, val);
  		break;
  	case BPF_JNE:
  		if (tnum_is_const(subreg))
  			return !tnum_equals_const(subreg, val);
  		break;
  	case BPF_JSET:
  		if ((~subreg.mask & subreg.value) & val)
  			return 1;
  		if (!((subreg.mask | subreg.value) & val))
  			return 0;
  		break;
  	case BPF_JGT:
  		if (reg->u32_min_value > val)
  			return 1;
  		else if (reg->u32_max_value <= val)
  			return 0;
  		break;
  	case BPF_JSGT:
  		if (reg->s32_min_value > sval)
  			return 1;
  		else if (reg->s32_max_value <= sval)
  			return 0;
  		break;
  	case BPF_JLT:
  		if (reg->u32_max_value < val)
  			return 1;
  		else if (reg->u32_min_value >= val)
  			return 0;
  		break;
  	case BPF_JSLT:
  		if (reg->s32_max_value < sval)
  			return 1;
  		else if (reg->s32_min_value >= sval)
  			return 0;
  		break;
  	case BPF_JGE:
  		if (reg->u32_min_value >= val)
  			return 1;
  		else if (reg->u32_max_value < val)
  			return 0;
  		break;
  	case BPF_JSGE:
  		if (reg->s32_min_value >= sval)
  			return 1;
  		else if (reg->s32_max_value < sval)
  			return 0;
  		break;
  	case BPF_JLE:
  		if (reg->u32_max_value <= val)
  			return 1;
  		else if (reg->u32_min_value > val)
  			return 0;
  		break;
  	case BPF_JSLE:
  		if (reg->s32_max_value <= sval)
  			return 1;
  		else if (reg->s32_min_value > sval)
  			return 0;
  		break;
  	}
  
  	return -1;
  }
  
  
  static int is_branch64_taken(struct bpf_reg_state *reg, u64 val, u8 opcode)
  {
  	s64 sval = (s64)val;
  
  	switch (opcode) {
  	case BPF_JEQ:
  		if (tnum_is_const(reg->var_off))
  			return !!tnum_equals_const(reg->var_off, val);
  		break;
  	case BPF_JNE:
  		if (tnum_is_const(reg->var_off))
  			return !tnum_equals_const(reg->var_off, val);
  		break;
  	case BPF_JSET:
  		if ((~reg->var_off.mask & reg->var_off.value) & val)
  			return 1;
  		if (!((reg->var_off.mask | reg->var_off.value) & val))
  			return 0;
  		break;
  	case BPF_JGT:
  		if (reg->umin_value > val)
  			return 1;
  		else if (reg->umax_value <= val)
  			return 0;
  		break;
  	case BPF_JSGT:
  		if (reg->smin_value > sval)
  			return 1;
  		else if (reg->smax_value <= sval)
  			return 0;
  		break;
  	case BPF_JLT:
  		if (reg->umax_value < val)
  			return 1;
  		else if (reg->umin_value >= val)
  			return 0;
  		break;
  	case BPF_JSLT:
  		if (reg->smax_value < sval)
  			return 1;
  		else if (reg->smin_value >= sval)
  			return 0;
  		break;
  	case BPF_JGE:
  		if (reg->umin_value >= val)
  			return 1;
  		else if (reg->umax_value < val)
  			return 0;
  		break;
  	case BPF_JSGE:
  		if (reg->smin_value >= sval)
  			return 1;
  		else if (reg->smax_value < sval)
  			return 0;
  		break;
  	case BPF_JLE:
  		if (reg->umax_value <= val)
  			return 1;
  		else if (reg->umin_value > val)
  			return 0;
  		break;
  	case BPF_JSLE:
  		if (reg->smax_value <= sval)
  			return 1;
  		else if (reg->smin_value > sval)
  			return 0;
  		break;
  	}
  
  	return -1;
  }
  
  /* compute branch direction of the expression "if (reg opcode val) goto target;"
   * and return:
   *  1 - branch will be taken and "goto target" will be executed
   *  0 - branch will not be taken and fall-through to next insn
   * -1 - unknown. Example: "if (reg < 5)" is unknown when register value
   *      range [0,10]
   */
  static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode,
  			   bool is_jmp32)
  {
  	if (__is_pointer_value(false, reg)) {
  		if (!reg_type_not_null(reg->type))
  			return -1;
  
  		/* If pointer is valid tests against zero will fail so we can
  		 * use this to direct branch taken.
  		 */
  		if (val != 0)
  			return -1;
  
  		switch (opcode) {
  		case BPF_JEQ:
  			return 0;
  		case BPF_JNE:
  			return 1;
  		default:
  			return -1;
  		}
  	}
  
  	if (is_jmp32)
  		return is_branch32_taken(reg, val, opcode);
  	return is_branch64_taken(reg, val, opcode);
  }
  
  static int flip_opcode(u32 opcode)
  {
  	/* How can we transform "a <op> b" into "b <op> a"? */
  	static const u8 opcode_flip[16] = {
  		/* these stay the same */
  		[BPF_JEQ  >> 4] = BPF_JEQ,
  		[BPF_JNE  >> 4] = BPF_JNE,
  		[BPF_JSET >> 4] = BPF_JSET,
  		/* these swap "lesser" and "greater" (L and G in the opcodes) */
  		[BPF_JGE  >> 4] = BPF_JLE,
  		[BPF_JGT  >> 4] = BPF_JLT,
  		[BPF_JLE  >> 4] = BPF_JGE,
  		[BPF_JLT  >> 4] = BPF_JGT,
  		[BPF_JSGE >> 4] = BPF_JSLE,
  		[BPF_JSGT >> 4] = BPF_JSLT,
  		[BPF_JSLE >> 4] = BPF_JSGE,
  		[BPF_JSLT >> 4] = BPF_JSGT
  	};
  	return opcode_flip[opcode >> 4];
  }
  
  static int is_pkt_ptr_branch_taken(struct bpf_reg_state *dst_reg,
  				   struct bpf_reg_state *src_reg,
  				   u8 opcode)
  {
  	struct bpf_reg_state *pkt;
  
  	if (src_reg->type == PTR_TO_PACKET_END) {
  		pkt = dst_reg;
  	} else if (dst_reg->type == PTR_TO_PACKET_END) {
  		pkt = src_reg;
  		opcode = flip_opcode(opcode);
  	} else {
  		return -1;
  	}
  
  	if (pkt->range >= 0)
  		return -1;
  
  	switch (opcode) {
  	case BPF_JLE:
  		/* pkt <= pkt_end */
  		fallthrough;
  	case BPF_JGT:
  		/* pkt > pkt_end */
  		if (pkt->range == BEYOND_PKT_END)
  			/* pkt has at last one extra byte beyond pkt_end */
  			return opcode == BPF_JGT;
  		break;
  	case BPF_JLT:
  		/* pkt < pkt_end */
  		fallthrough;
  	case BPF_JGE:
  		/* pkt >= pkt_end */
  		if (pkt->range == BEYOND_PKT_END || pkt->range == AT_PKT_END)
  			return opcode == BPF_JGE;
  		break;
  	}
  	return -1;
  }
  
  /* Adjusts the register min/max values in the case that the dst_reg is the
   * variable register that we are working on, and src_reg is a constant or we're
   * simply doing a BPF_K check.
   * In JEQ/JNE cases we also adjust the var_off values.
   */
  static void reg_set_min_max(struct bpf_reg_state *true_reg,
  			    struct bpf_reg_state *false_reg,
  			    u64 val, u32 val32,
  			    u8 opcode, bool is_jmp32)
  {
  	struct tnum false_32off = tnum_subreg(false_reg->var_off);
  	struct tnum false_64off = false_reg->var_off;
  	struct tnum true_32off = tnum_subreg(true_reg->var_off);
  	struct tnum true_64off = true_reg->var_off;
  	s64 sval = (s64)val;
  	s32 sval32 = (s32)val32;
  
  	/* If the dst_reg is a pointer, we can't learn anything about its
  	 * variable offset from the compare (unless src_reg were a pointer into
  	 * the same object, but we don't bother with that.
  	 * Since false_reg and true_reg have the same type by construction, we
  	 * only need to check one of them for pointerness.
  	 */
  	if (__is_pointer_value(false, false_reg))
  		return;
  
  	switch (opcode) {
  	case BPF_JEQ:
  	case BPF_JNE:
  	{
  		struct bpf_reg_state *reg =
  			opcode == BPF_JEQ ? true_reg : false_reg;
  
  		/* JEQ/JNE comparison doesn't change the register equivalence.
  		 * r1 = r2;
  		 * if (r1 == 42) goto label;
  		 * ...
  		 * label: // here both r1 and r2 are known to be 42.
  		 *
  		 * Hence when marking register as known preserve it's ID.
  		 */
  		if (is_jmp32)
  			__mark_reg32_known(reg, val32);
  		else
  			___mark_reg_known(reg, val);
  		break;
  	}
  	case BPF_JSET:
  		if (is_jmp32) {
  			false_32off = tnum_and(false_32off, tnum_const(~val32));
  			if (is_power_of_2(val32))
  				true_32off = tnum_or(true_32off,
  						     tnum_const(val32));
  		} else {
  			false_64off = tnum_and(false_64off, tnum_const(~val));
  			if (is_power_of_2(val))
  				true_64off = tnum_or(true_64off,
  						     tnum_const(val));
  		}
  		break;
  	case BPF_JGE:
  	case BPF_JGT:
  	{
  		if (is_jmp32) {
  			u32 false_umax = opcode == BPF_JGT ? val32  : val32 - 1;
  			u32 true_umin = opcode == BPF_JGT ? val32 + 1 : val32;
  
  			false_reg->u32_max_value = min(false_reg->u32_max_value,
  						       false_umax);
  			true_reg->u32_min_value = max(true_reg->u32_min_value,
  						      true_umin);
  		} else {
  			u64 false_umax = opcode == BPF_JGT ? val    : val - 1;
  			u64 true_umin = opcode == BPF_JGT ? val + 1 : val;
  
  			false_reg->umax_value = min(false_reg->umax_value, false_umax);
  			true_reg->umin_value = max(true_reg->umin_value, true_umin);
  		}
  		break;
  	}
  	case BPF_JSGE:
  	case BPF_JSGT:
  	{
  		if (is_jmp32) {
  			s32 false_smax = opcode == BPF_JSGT ? sval32    : sval32 - 1;
  			s32 true_smin = opcode == BPF_JSGT ? sval32 + 1 : sval32;
  
  			false_reg->s32_max_value = min(false_reg->s32_max_value, false_smax);
  			true_reg->s32_min_value = max(true_reg->s32_min_value, true_smin);
  		} else {
  			s64 false_smax = opcode == BPF_JSGT ? sval    : sval - 1;
  			s64 true_smin = opcode == BPF_JSGT ? sval + 1 : sval;
  
  			false_reg->smax_value = min(false_reg->smax_value, false_smax);
  			true_reg->smin_value = max(true_reg->smin_value, true_smin);
  		}
  		break;
  	}
  	case BPF_JLE:
  	case BPF_JLT:
  	{
  		if (is_jmp32) {
  			u32 false_umin = opcode == BPF_JLT ? val32  : val32 + 1;
  			u32 true_umax = opcode == BPF_JLT ? val32 - 1 : val32;
  
  			false_reg->u32_min_value = max(false_reg->u32_min_value,
  						       false_umin);
  			true_reg->u32_max_value = min(true_reg->u32_max_value,
  						      true_umax);
  		} else {
  			u64 false_umin = opcode == BPF_JLT ? val    : val + 1;
  			u64 true_umax = opcode == BPF_JLT ? val - 1 : val;
  
  			false_reg->umin_value = max(false_reg->umin_value, false_umin);
  			true_reg->umax_value = min(true_reg->umax_value, true_umax);
  		}
  		break;
  	}
  	case BPF_JSLE:
  	case BPF_JSLT:
  	{
  		if (is_jmp32) {
  			s32 false_smin = opcode == BPF_JSLT ? sval32    : sval32 + 1;
  			s32 true_smax = opcode == BPF_JSLT ? sval32 - 1 : sval32;
  
  			false_reg->s32_min_value = max(false_reg->s32_min_value, false_smin);
  			true_reg->s32_max_value = min(true_reg->s32_max_value, true_smax);
  		} else {
  			s64 false_smin = opcode == BPF_JSLT ? sval    : sval + 1;
  			s64 true_smax = opcode == BPF_JSLT ? sval - 1 : sval;
  
  			false_reg->smin_value = max(false_reg->smin_value, false_smin);
  			true_reg->smax_value = min(true_reg->smax_value, true_smax);
  		}
  		break;
  	}
  	default:
  		return;
  	}
  
  	if (is_jmp32) {
  		false_reg->var_off = tnum_or(tnum_clear_subreg(false_64off),
  					     tnum_subreg(false_32off));
  		true_reg->var_off = tnum_or(tnum_clear_subreg(true_64off),
  					    tnum_subreg(true_32off));
  		__reg_combine_32_into_64(false_reg);
  		__reg_combine_32_into_64(true_reg);
  	} else {
  		false_reg->var_off = false_64off;
  		true_reg->var_off = true_64off;
  		__reg_combine_64_into_32(false_reg);
  		__reg_combine_64_into_32(true_reg);
  	}
  }
  
  /* Same as above, but for the case that dst_reg holds a constant and src_reg is
   * the variable reg.
   */
  static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
  				struct bpf_reg_state *false_reg,
  				u64 val, u32 val32,
  				u8 opcode, bool is_jmp32)
  {
  	opcode = flip_opcode(opcode);
  	/* This uses zero as "not present in table"; luckily the zero opcode,
  	 * BPF_JA, can't get here.
  	 */
  	if (opcode)
  		reg_set_min_max(true_reg, false_reg, val, val32, opcode, is_jmp32);
  }
  
  /* Regs are known to be equal, so intersect their min/max/var_off */
  static void __reg_combine_min_max(struct bpf_reg_state *src_reg,
  				  struct bpf_reg_state *dst_reg)
  {
  	src_reg->umin_value = dst_reg->umin_value = max(src_reg->umin_value,
  							dst_reg->umin_value);
  	src_reg->umax_value = dst_reg->umax_value = min(src_reg->umax_value,
  							dst_reg->umax_value);
  	src_reg->smin_value = dst_reg->smin_value = max(src_reg->smin_value,
  							dst_reg->smin_value);
  	src_reg->smax_value = dst_reg->smax_value = min(src_reg->smax_value,
  							dst_reg->smax_value);
  	src_reg->var_off = dst_reg->var_off = tnum_intersect(src_reg->var_off,
  							     dst_reg->var_off);
  	/* We might have learned new bounds from the var_off. */
  	__update_reg_bounds(src_reg);
  	__update_reg_bounds(dst_reg);
  	/* We might have learned something about the sign bit. */
  	__reg_deduce_bounds(src_reg);
  	__reg_deduce_bounds(dst_reg);
  	/* We might have learned some bits from the bounds. */
  	__reg_bound_offset(src_reg);
  	__reg_bound_offset(dst_reg);
  	/* Intersecting with the old var_off might have improved our bounds
  	 * slightly.  e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
  	 * then new var_off is (0; 0x7f...fc) which improves our umax.
  	 */
  	__update_reg_bounds(src_reg);
  	__update_reg_bounds(dst_reg);
  }
  
  static void reg_combine_min_max(struct bpf_reg_state *true_src,
  				struct bpf_reg_state *true_dst,
  				struct bpf_reg_state *false_src,
  				struct bpf_reg_state *false_dst,
  				u8 opcode)
  {
  	switch (opcode) {
  	case BPF_JEQ:
  		__reg_combine_min_max(true_src, true_dst);
  		break;
  	case BPF_JNE:
  		__reg_combine_min_max(false_src, false_dst);
  		break;
  	}
  }
  
  static void mark_ptr_or_null_reg(struct bpf_func_state *state,
  				 struct bpf_reg_state *reg, u32 id,
  				 bool is_null)
  {
  	if (type_may_be_null(reg->type) && reg->id == id &&
  	    !WARN_ON_ONCE(!reg->id)) {
  		if (WARN_ON_ONCE(reg->smin_value || reg->smax_value ||
  				 !tnum_equals_const(reg->var_off, 0) ||
  				 reg->off)) {
  			/* Old offset (both fixed and variable parts) should
  			 * have been known-zero, because we don't allow pointer
  			 * arithmetic on pointers that might be NULL. If we
  			 * see this happening, don't convert the register.
  			 */
  			return;
  		}
  		if (is_null) {
  			reg->type = SCALAR_VALUE;
  			/* We don't need id and ref_obj_id from this point
  			 * onwards anymore, thus we should better reset it,
  			 * so that state pruning has chances to take effect.
  			 */
  			reg->id = 0;
  			reg->ref_obj_id = 0;
  
  			return;
  		}
  
  		mark_ptr_not_null_reg(reg);
  
  		if (!reg_may_point_to_spin_lock(reg)) {
  			/* For not-NULL ptr, reg->ref_obj_id will be reset
  			 * in release_reg_references().
  			 *
  			 * reg->id is still used by spin_lock ptr. Other
  			 * than spin_lock ptr type, reg->id can be reset.
  			 */
  			reg->id = 0;
  		}
  	}
  }
  
  static void __mark_ptr_or_null_regs(struct bpf_func_state *state, u32 id,
  				    bool is_null)
  {
  	struct bpf_reg_state *reg;
  	int i;
  
  	for (i = 0; i < MAX_BPF_REG; i++)
  		mark_ptr_or_null_reg(state, &state->regs[i], id, is_null);
  
  	bpf_for_each_spilled_reg(i, state, reg) {
  		if (!reg)
  			continue;
  		mark_ptr_or_null_reg(state, reg, id, is_null);
  	}
  }
  
  /* The logic is similar to find_good_pkt_pointers(), both could eventually
   * be folded together at some point.
   */
  static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno,
  				  bool is_null)
  {
  	struct bpf_func_state *state = vstate->frame[vstate->curframe];
  	struct bpf_reg_state *regs = state->regs;
  	u32 ref_obj_id = regs[regno].ref_obj_id;
  	u32 id = regs[regno].id;
  	int i;
  
  	if (ref_obj_id && ref_obj_id == id && is_null)
  		/* regs[regno] is in the " == NULL" branch.
  		 * No one could have freed the reference state before
  		 * doing the NULL check.
  		 */
  		WARN_ON_ONCE(release_reference_state(state, id));
  
  	for (i = 0; i <= vstate->curframe; i++)
  		__mark_ptr_or_null_regs(vstate->frame[i], id, is_null);
  }
  
  static bool try_match_pkt_pointers(const struct bpf_insn *insn,
  				   struct bpf_reg_state *dst_reg,
  				   struct bpf_reg_state *src_reg,
  				   struct bpf_verifier_state *this_branch,
  				   struct bpf_verifier_state *other_branch)
  {
  	if (BPF_SRC(insn->code) != BPF_X)
  		return false;
  
  	/* Pointers are always 64-bit. */
  	if (BPF_CLASS(insn->code) == BPF_JMP32)
  		return false;
  
  	switch (BPF_OP(insn->code)) {
  	case BPF_JGT:
  		if ((dst_reg->type == PTR_TO_PACKET &&
  		     src_reg->type == PTR_TO_PACKET_END) ||
  		    (dst_reg->type == PTR_TO_PACKET_META &&
  		     reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
  			/* pkt_data' > pkt_end, pkt_meta' > pkt_data */
  			find_good_pkt_pointers(this_branch, dst_reg,
  					       dst_reg->type, false);
  			mark_pkt_end(other_branch, insn->dst_reg, true);
  		} else if ((dst_reg->type == PTR_TO_PACKET_END &&
  			    src_reg->type == PTR_TO_PACKET) ||
  			   (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
  			    src_reg->type == PTR_TO_PACKET_META)) {
  			/* pkt_end > pkt_data', pkt_data > pkt_meta' */
  			find_good_pkt_pointers(other_branch, src_reg,
  					       src_reg->type, true);
  			mark_pkt_end(this_branch, insn->src_reg, false);
  		} else {
  			return false;
  		}
  		break;
  	case BPF_JLT:
  		if ((dst_reg->type == PTR_TO_PACKET &&
  		     src_reg->type == PTR_TO_PACKET_END) ||
  		    (dst_reg->type == PTR_TO_PACKET_META &&
  		     reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
  			/* pkt_data' < pkt_end, pkt_meta' < pkt_data */
  			find_good_pkt_pointers(other_branch, dst_reg,
  					       dst_reg->type, true);
  			mark_pkt_end(this_branch, insn->dst_reg, false);
  		} else if ((dst_reg->type == PTR_TO_PACKET_END &&
  			    src_reg->type == PTR_TO_PACKET) ||
  			   (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
  			    src_reg->type == PTR_TO_PACKET_META)) {
  			/* pkt_end < pkt_data', pkt_data > pkt_meta' */
  			find_good_pkt_pointers(this_branch, src_reg,
  					       src_reg->type, false);
  			mark_pkt_end(other_branch, insn->src_reg, true);
  		} else {
  			return false;
  		}
  		break;
  	case BPF_JGE:
  		if ((dst_reg->type == PTR_TO_PACKET &&
  		     src_reg->type == PTR_TO_PACKET_END) ||
  		    (dst_reg->type == PTR_TO_PACKET_META &&
  		     reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
  			/* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */
  			find_good_pkt_pointers(this_branch, dst_reg,
  					       dst_reg->type, true);
  			mark_pkt_end(other_branch, insn->dst_reg, false);
  		} else if ((dst_reg->type == PTR_TO_PACKET_END &&
  			    src_reg->type == PTR_TO_PACKET) ||
  			   (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
  			    src_reg->type == PTR_TO_PACKET_META)) {
  			/* pkt_end >= pkt_data', pkt_data >= pkt_meta' */
  			find_good_pkt_pointers(other_branch, src_reg,
  					       src_reg->type, false);
  			mark_pkt_end(this_branch, insn->src_reg, true);
  		} else {
  			return false;
  		}
  		break;
  	case BPF_JLE:
  		if ((dst_reg->type == PTR_TO_PACKET &&
  		     src_reg->type == PTR_TO_PACKET_END) ||
  		    (dst_reg->type == PTR_TO_PACKET_META &&
  		     reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
  			/* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */
  			find_good_pkt_pointers(other_branch, dst_reg,
  					       dst_reg->type, false);
  			mark_pkt_end(this_branch, insn->dst_reg, true);
  		} else if ((dst_reg->type == PTR_TO_PACKET_END &&
  			    src_reg->type == PTR_TO_PACKET) ||
  			   (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
  			    src_reg->type == PTR_TO_PACKET_META)) {
  			/* pkt_end <= pkt_data', pkt_data <= pkt_meta' */
  			find_good_pkt_pointers(this_branch, src_reg,
  					       src_reg->type, true);
  			mark_pkt_end(other_branch, insn->src_reg, false);
  		} else {
  			return false;
  		}
  		break;
  	default:
  		return false;
  	}
  
  	return true;
  }
  
  static void find_equal_scalars(struct bpf_verifier_state *vstate,
  			       struct bpf_reg_state *known_reg)
  {
  	struct bpf_func_state *state;
  	struct bpf_reg_state *reg;
  	int i, j;
  
  	for (i = 0; i <= vstate->curframe; i++) {
  		state = vstate->frame[i];
  		for (j = 0; j < MAX_BPF_REG; j++) {
  			reg = &state->regs[j];
  			if (reg->type == SCALAR_VALUE && reg->id == known_reg->id)
  				*reg = *known_reg;
  		}
  
  		bpf_for_each_spilled_reg(j, state, reg) {
  			if (!reg)
  				continue;
  			if (reg->type == SCALAR_VALUE && reg->id == known_reg->id)
  				*reg = *known_reg;
  		}
  	}
  }
  
  static int check_cond_jmp_op(struct bpf_verifier_env *env,
  			     struct bpf_insn *insn, int *insn_idx)
  {
  	struct bpf_verifier_state *this_branch = env->cur_state;
  	struct bpf_verifier_state *other_branch;
  	struct bpf_reg_state *regs = this_branch->frame[this_branch->curframe]->regs;
  	struct bpf_reg_state *dst_reg, *other_branch_regs, *src_reg = NULL;
  	u8 opcode = BPF_OP(insn->code);
  	bool is_jmp32;
  	int pred = -1;
  	int err;
  
  	/* Only conditional jumps are expected to reach here. */
  	if (opcode == BPF_JA || opcode > BPF_JSLE) {
  		verbose(env, "invalid BPF_JMP/JMP32 opcode %x\n", opcode);
  		return -EINVAL;
  	}
  
  	if (BPF_SRC(insn->code) == BPF_X) {
  		if (insn->imm != 0) {
  			verbose(env, "BPF_JMP/JMP32 uses reserved fields\n");
  			return -EINVAL;
  		}
  
  		/* check src1 operand */
  		err = check_reg_arg(env, insn->src_reg, SRC_OP);
  		if (err)
  			return err;
  
  		if (is_pointer_value(env, insn->src_reg)) {
  			verbose(env, "R%d pointer comparison prohibited\n",
  				insn->src_reg);
  			return -EACCES;
  		}
  		src_reg = &regs[insn->src_reg];
  	} else {
  		if (insn->src_reg != BPF_REG_0) {
  			verbose(env, "BPF_JMP/JMP32 uses reserved fields\n");
  			return -EINVAL;
  		}
  	}
  
  	/* check src2 operand */
  	err = check_reg_arg(env, insn->dst_reg, SRC_OP);
  	if (err)
  		return err;
  
  	dst_reg = &regs[insn->dst_reg];
  	is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
  
  	if (BPF_SRC(insn->code) == BPF_K) {
  		pred = is_branch_taken(dst_reg, insn->imm, opcode, is_jmp32);
  	} else if (src_reg->type == SCALAR_VALUE &&
  		   is_jmp32 && tnum_is_const(tnum_subreg(src_reg->var_off))) {
  		pred = is_branch_taken(dst_reg,
  				       tnum_subreg(src_reg->var_off).value,
  				       opcode,
  				       is_jmp32);
  	} else if (src_reg->type == SCALAR_VALUE &&
  		   !is_jmp32 && tnum_is_const(src_reg->var_off)) {
  		pred = is_branch_taken(dst_reg,
  				       src_reg->var_off.value,
  				       opcode,
  				       is_jmp32);
  	} else if (reg_is_pkt_pointer_any(dst_reg) &&
  		   reg_is_pkt_pointer_any(src_reg) &&
  		   !is_jmp32) {
  		pred = is_pkt_ptr_branch_taken(dst_reg, src_reg, opcode);
  	}
  
  	if (pred >= 0) {
  		/* If we get here with a dst_reg pointer type it is because
  		 * above is_branch_taken() special cased the 0 comparison.
  		 */
  		if (!__is_pointer_value(false, dst_reg))
  			err = mark_chain_precision(env, insn->dst_reg);
  		if (BPF_SRC(insn->code) == BPF_X && !err &&
  		    !__is_pointer_value(false, src_reg))
  			err = mark_chain_precision(env, insn->src_reg);
  		if (err)
  			return err;
  	}
  
  	if (pred == 1) {
  		/* Only follow the goto, ignore fall-through. If needed, push
  		 * the fall-through branch for simulation under speculative
  		 * execution.
  		 */
  		if (!env->bypass_spec_v1 &&
  		    !sanitize_speculative_path(env, insn, *insn_idx + 1,
  					       *insn_idx))
  			return -EFAULT;
  		*insn_idx += insn->off;
  		return 0;
  	} else if (pred == 0) {
  		/* Only follow the fall-through branch, since that's where the
  		 * program will go. If needed, push the goto branch for
  		 * simulation under speculative execution.
  		 */
  		if (!env->bypass_spec_v1 &&
  		    !sanitize_speculative_path(env, insn,
  					       *insn_idx + insn->off + 1,
  					       *insn_idx))
  			return -EFAULT;
  		return 0;
  	}
  
  	other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx,
  				  false);
  	if (!other_branch)
  		return -EFAULT;
  	other_branch_regs = other_branch->frame[other_branch->curframe]->regs;
  
  	/* detect if we are comparing against a constant value so we can adjust
  	 * our min/max values for our dst register.
  	 * this is only legit if both are scalars (or pointers to the same
  	 * object, I suppose, but we don't support that right now), because
  	 * otherwise the different base pointers mean the offsets aren't
  	 * comparable.
  	 */
  	if (BPF_SRC(insn->code) == BPF_X) {
  		struct bpf_reg_state *src_reg = &regs[insn->src_reg];
  
  		if (dst_reg->type == SCALAR_VALUE &&
  		    src_reg->type == SCALAR_VALUE) {
  			if (tnum_is_const(src_reg->var_off) ||
  			    (is_jmp32 &&
  			     tnum_is_const(tnum_subreg(src_reg->var_off))))
  				reg_set_min_max(&other_branch_regs[insn->dst_reg],
  						dst_reg,
  						src_reg->var_off.value,
  						tnum_subreg(src_reg->var_off).value,
  						opcode, is_jmp32);
  			else if (tnum_is_const(dst_reg->var_off) ||
  				 (is_jmp32 &&
  				  tnum_is_const(tnum_subreg(dst_reg->var_off))))
  				reg_set_min_max_inv(&other_branch_regs[insn->src_reg],
  						    src_reg,
  						    dst_reg->var_off.value,
  						    tnum_subreg(dst_reg->var_off).value,
  						    opcode, is_jmp32);
  			else if (!is_jmp32 &&
  				 (opcode == BPF_JEQ || opcode == BPF_JNE))
  				/* Comparing for equality, we can combine knowledge */
  				reg_combine_min_max(&other_branch_regs[insn->src_reg],
  						    &other_branch_regs[insn->dst_reg],
  						    src_reg, dst_reg, opcode);
  			if (src_reg->id &&
  			    !WARN_ON_ONCE(src_reg->id != other_branch_regs[insn->src_reg].id)) {
  				find_equal_scalars(this_branch, src_reg);
  				find_equal_scalars(other_branch, &other_branch_regs[insn->src_reg]);
  			}
  
  		}
  	} else if (dst_reg->type == SCALAR_VALUE) {
  		reg_set_min_max(&other_branch_regs[insn->dst_reg],
  					dst_reg, insn->imm, (u32)insn->imm,
  					opcode, is_jmp32);
  	}
  
  	if (dst_reg->type == SCALAR_VALUE && dst_reg->id &&
  	    !WARN_ON_ONCE(dst_reg->id != other_branch_regs[insn->dst_reg].id)) {
  		find_equal_scalars(this_branch, dst_reg);
  		find_equal_scalars(other_branch, &other_branch_regs[insn->dst_reg]);
  	}
  
  	/* detect if R == 0 where R is returned from bpf_map_lookup_elem().
  	 * NOTE: these optimizations below are related with pointer comparison
  	 *       which will never be JMP32.
  	 */
  	if (!is_jmp32 && BPF_SRC(insn->code) == BPF_K &&
  	    insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
  	    type_may_be_null(dst_reg->type)) {
  		/* Mark all identical registers in each branch as either
  		 * safe or unknown depending R == 0 or R != 0 conditional.
  		 */
  		mark_ptr_or_null_regs(this_branch, insn->dst_reg,
  				      opcode == BPF_JNE);
  		mark_ptr_or_null_regs(other_branch, insn->dst_reg,
  				      opcode == BPF_JEQ);
  	} else if (!try_match_pkt_pointers(insn, dst_reg, &regs[insn->src_reg],
  					   this_branch, other_branch) &&
  		   is_pointer_value(env, insn->dst_reg)) {
  		verbose(env, "R%d pointer comparison prohibited\n",
  			insn->dst_reg);
  		return -EACCES;
  	}
  	if (env->log.level & BPF_LOG_LEVEL)
  		print_insn_state(env, this_branch->frame[this_branch->curframe]);
  	return 0;
  }
  
  /* verify BPF_LD_IMM64 instruction */
  static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
  {
  	struct bpf_insn_aux_data *aux = cur_aux(env);
  	struct bpf_reg_state *regs = cur_regs(env);
  	struct bpf_reg_state *dst_reg;
  	struct bpf_map *map;
  	int err;
  
  	if (BPF_SIZE(insn->code) != BPF_DW) {
  		verbose(env, "invalid BPF_LD_IMM insn\n");
  		return -EINVAL;
  	}
  	if (insn->off != 0) {
  		verbose(env, "BPF_LD_IMM64 uses reserved fields\n");
  		return -EINVAL;
  	}
  
  	err = check_reg_arg(env, insn->dst_reg, DST_OP);
  	if (err)
  		return err;
  
  	dst_reg = &regs[insn->dst_reg];
  	if (insn->src_reg == 0) {
  		u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
  
  		dst_reg->type = SCALAR_VALUE;
  		__mark_reg_known(&regs[insn->dst_reg], imm);
  		return 0;
  	}
  
  	/* All special src_reg cases are listed below. From this point onwards
  	 * we either succeed and assign a corresponding dst_reg->type after
  	 * zeroing the offset, or fail and reject the program.
  	 */
  	mark_reg_known_zero(env, regs, insn->dst_reg);
  
  	if (insn->src_reg == BPF_PSEUDO_BTF_ID) {
  		dst_reg->type = aux->btf_var.reg_type;
  		switch (base_type(dst_reg->type)) {
  		case PTR_TO_MEM:
  			dst_reg->mem_size = aux->btf_var.mem_size;
  			break;
  		case PTR_TO_BTF_ID:
  			dst_reg->btf = aux->btf_var.btf;
  			dst_reg->btf_id = aux->btf_var.btf_id;
  			break;
  		default:
  			verbose(env, "bpf verifier is misconfigured\n");
  			return -EFAULT;
  		}
  		return 0;
  	}
  
  	if (insn->src_reg == BPF_PSEUDO_FUNC) {
  		struct bpf_prog_aux *aux = env->prog->aux;
  		u32 subprogno = find_subprog(env,
  					     env->insn_idx + insn->imm + 1);
  
  		if (!aux->func_info) {
  			verbose(env, "missing btf func_info\n");
  			return -EINVAL;
  		}
  		if (aux->func_info_aux[subprogno].linkage != BTF_FUNC_STATIC) {
  			verbose(env, "callback function not static\n");
  			return -EINVAL;
  		}
  
  		dst_reg->type = PTR_TO_FUNC;
  		dst_reg->subprogno = subprogno;
  		return 0;
  	}
  
  	map = env->used_maps[aux->map_index];
  	dst_reg->map_ptr = map;
  
  	if (insn->src_reg == BPF_PSEUDO_MAP_VALUE ||
  	    insn->src_reg == BPF_PSEUDO_MAP_IDX_VALUE) {
  		dst_reg->type = PTR_TO_MAP_VALUE;
  		dst_reg->off = aux->map_off;
  		if (map_value_has_spin_lock(map))
  			dst_reg->id = ++env->id_gen;
  	} else if (insn->src_reg == BPF_PSEUDO_MAP_FD ||
  		   insn->src_reg == BPF_PSEUDO_MAP_IDX) {
  		dst_reg->type = CONST_PTR_TO_MAP;
  	} else {
  		verbose(env, "bpf verifier is misconfigured\n");
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  static bool may_access_skb(enum bpf_prog_type type)
  {
  	switch (type) {
  	case BPF_PROG_TYPE_SOCKET_FILTER:
  	case BPF_PROG_TYPE_SCHED_CLS:
  	case BPF_PROG_TYPE_SCHED_ACT:
  		return true;
  	default:
  		return false;
  	}
  }
  
  /* verify safety of LD_ABS|LD_IND instructions:
   * - they can only appear in the programs where ctx == skb
   * - since they are wrappers of function calls, they scratch R1-R5 registers,
   *   preserve R6-R9, and store return value into R0
   *
   * Implicit input:
   *   ctx == skb == R6 == CTX
   *
   * Explicit input:
   *   SRC == any register
   *   IMM == 32-bit immediate
   *
   * Output:
   *   R0 - 8/16/32-bit skb data converted to cpu endianness
   */
  static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
  {
  	struct bpf_reg_state *regs = cur_regs(env);
  	static const int ctx_reg = BPF_REG_6;
  	u8 mode = BPF_MODE(insn->code);
  	int i, err;
  
  	if (!may_access_skb(resolve_prog_type(env->prog))) {
  		verbose(env, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
  		return -EINVAL;
  	}
  
  	if (!env->ops->gen_ld_abs) {
  		verbose(env, "bpf verifier is misconfigured\n");
  		return -EINVAL;
  	}
  
  	if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
  	    BPF_SIZE(insn->code) == BPF_DW ||
  	    (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
  		verbose(env, "BPF_LD_[ABS|IND] uses reserved fields\n");
  		return -EINVAL;
  	}
  
  	/* check whether implicit source operand (register R6) is readable */
  	err = check_reg_arg(env, ctx_reg, SRC_OP);
  	if (err)
  		return err;
  
  	/* Disallow usage of BPF_LD_[ABS|IND] with reference tracking, as
  	 * gen_ld_abs() may terminate the program at runtime, leading to
  	 * reference leak.
  	 */
  	err = check_reference_leak(env);
  	if (err) {
  		verbose(env, "BPF_LD_[ABS|IND] cannot be mixed with socket references\n");
  		return err;
  	}
  
  	if (env->cur_state->active_spin_lock) {
  		verbose(env, "BPF_LD_[ABS|IND] cannot be used inside bpf_spin_lock-ed region\n");
  		return -EINVAL;
  	}
  
  	if (regs[ctx_reg].type != PTR_TO_CTX) {
  		verbose(env,
  			"at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
  		return -EINVAL;
  	}
  
  	if (mode == BPF_IND) {
  		/* check explicit source operand */
  		err = check_reg_arg(env, insn->src_reg, SRC_OP);
  		if (err)
  			return err;
  	}
  
  	err = check_ptr_off_reg(env, &regs[ctx_reg], ctx_reg);
  	if (err < 0)
  		return err;
  
  	/* reset caller saved regs to unreadable */
  	for (i = 0; i < CALLER_SAVED_REGS; i++) {
  		mark_reg_not_init(env, regs, caller_saved[i]);
  		check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
  	}
  
  	/* mark destination R0 register as readable, since it contains
  	 * the value fetched from the packet.
  	 * Already marked as written above.
  	 */
  	mark_reg_unknown(env, regs, BPF_REG_0);
  	/* ld_abs load up to 32-bit skb data. */
  	regs[BPF_REG_0].subreg_def = env->insn_idx + 1;
  	return 0;
  }
  
  static int check_return_code(struct bpf_verifier_env *env)
  {
  	struct tnum enforce_attach_type_range = tnum_unknown;
  	const struct bpf_prog *prog = env->prog;
  	struct bpf_reg_state *reg;
  	struct tnum range = tnum_range(0, 1);
  	enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
  	int err;
  	struct bpf_func_state *frame = env->cur_state->frame[0];
  	const bool is_subprog = frame->subprogno;
  
  	/* LSM and struct_ops func-ptr's return type could be "void" */
  	if (!is_subprog &&
  	    (prog_type == BPF_PROG_TYPE_STRUCT_OPS ||
  	     prog_type == BPF_PROG_TYPE_LSM) &&
  	    !prog->aux->attach_func_proto->type)
  		return 0;
  
  	/* eBPF calling convention is such that R0 is used
  	 * to return the value from eBPF program.
  	 * Make sure that it's readable at this time
  	 * of bpf_exit, which means that program wrote
  	 * something into it earlier
  	 */
  	err = check_reg_arg(env, BPF_REG_0, SRC_OP);
  	if (err)
  		return err;
  
  	if (is_pointer_value(env, BPF_REG_0)) {
  		verbose(env, "R0 leaks addr as return value\n");
  		return -EACCES;
  	}
  
  	reg = cur_regs(env) + BPF_REG_0;
  
  	if (frame->in_async_callback_fn) {
  		/* enforce return zero from async callbacks like timer */
  		if (reg->type != SCALAR_VALUE) {
  			verbose(env, "In async callback the register R0 is not a known value (%s)\n",
  				reg_type_str(env, reg->type));
  			return -EINVAL;
  		}
  
  		if (!tnum_in(tnum_const(0), reg->var_off)) {
  			verbose_invalid_scalar(env, reg, &range, "async callback", "R0");
  			return -EINVAL;
  		}
  		return 0;
  	}
  
  	if (is_subprog) {
  		if (reg->type != SCALAR_VALUE) {
  			verbose(env, "At subprogram exit the register R0 is not a scalar value (%s)\n",
  				reg_type_str(env, reg->type));
  			return -EINVAL;
  		}
  		return 0;
  	}
  
  	switch (prog_type) {
  	case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
  		if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG ||
  		    env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG ||
  		    env->prog->expected_attach_type == BPF_CGROUP_INET4_GETPEERNAME ||
  		    env->prog->expected_attach_type == BPF_CGROUP_INET6_GETPEERNAME ||
  		    env->prog->expected_attach_type == BPF_CGROUP_INET4_GETSOCKNAME ||
  		    env->prog->expected_attach_type == BPF_CGROUP_INET6_GETSOCKNAME)
  			range = tnum_range(1, 1);
  		if (env->prog->expected_attach_type == BPF_CGROUP_INET4_BIND ||
  		    env->prog->expected_attach_type == BPF_CGROUP_INET6_BIND)
  			range = tnum_range(0, 3);
  		break;
  	case BPF_PROG_TYPE_CGROUP_SKB:
  		if (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS) {
  			range = tnum_range(0, 3);
  			enforce_attach_type_range = tnum_range(2, 3);
  		}
  		break;
  	case BPF_PROG_TYPE_CGROUP_SOCK:
  	case BPF_PROG_TYPE_SOCK_OPS:
  	case BPF_PROG_TYPE_CGROUP_DEVICE:
  	case BPF_PROG_TYPE_CGROUP_SYSCTL:
  	case BPF_PROG_TYPE_CGROUP_SOCKOPT:
  		break;
  	case BPF_PROG_TYPE_RAW_TRACEPOINT:
  		if (!env->prog->aux->attach_btf_id)
  			return 0;
  		range = tnum_const(0);
  		break;
  	case BPF_PROG_TYPE_TRACING:
  		switch (env->prog->expected_attach_type) {
  		case BPF_TRACE_FENTRY:
  		case BPF_TRACE_FEXIT:
  			range = tnum_const(0);
  			break;
  		case BPF_TRACE_RAW_TP:
  		case BPF_MODIFY_RETURN:
  			return 0;
  		case BPF_TRACE_ITER:
  			break;
  		default:
  			return -ENOTSUPP;
  		}
  		break;
  	case BPF_PROG_TYPE_SK_LOOKUP:
  		range = tnum_range(SK_DROP, SK_PASS);
  		break;
  	case BPF_PROG_TYPE_EXT:
  		/* freplace program can return anything as its return value
  		 * depends on the to-be-replaced kernel func or bpf program.
  		 */
  	default:
  		return 0;
  	}
  
  	if (reg->type != SCALAR_VALUE) {
  		verbose(env, "At program exit the register R0 is not a known value (%s)\n",
  			reg_type_str(env, reg->type));
  		return -EINVAL;
  	}
  
  	if (!tnum_in(range, reg->var_off)) {
  		verbose_invalid_scalar(env, reg, &range, "program exit", "R0");
  		return -EINVAL;
  	}
  
  	if (!tnum_is_unknown(enforce_attach_type_range) &&
  	    tnum_in(enforce_attach_type_range, reg->var_off))
  		env->prog->enforce_expected_attach_type = 1;
  	return 0;
  }
  
  /* non-recursive DFS pseudo code
   * 1  procedure DFS-iterative(G,v):
   * 2      label v as discovered
   * 3      let S be a stack
   * 4      S.push(v)
   * 5      while S is not empty
   * 6            t <- S.pop()
   * 7            if t is what we're looking for:
   * 8                return t
   * 9            for all edges e in G.adjacentEdges(t) do
   * 10               if edge e is already labelled
   * 11                   continue with the next edge
   * 12               w <- G.adjacentVertex(t,e)
   * 13               if vertex w is not discovered and not explored
   * 14                   label e as tree-edge
   * 15                   label w as discovered
   * 16                   S.push(w)
   * 17                   continue at 5
   * 18               else if vertex w is discovered
   * 19                   label e as back-edge
   * 20               else
   * 21                   // vertex w is explored
   * 22                   label e as forward- or cross-edge
   * 23           label t as explored
   * 24           S.pop()
   *
   * convention:
   * 0x10 - discovered
   * 0x11 - discovered and fall-through edge labelled
   * 0x12 - discovered and fall-through and branch edges labelled
   * 0x20 - explored
   */
  
  enum {
  	DISCOVERED = 0x10,
  	EXPLORED = 0x20,
  	FALLTHROUGH = 1,
  	BRANCH = 2,
  };
  
  static u32 state_htab_size(struct bpf_verifier_env *env)
  {
  	return env->prog->len;
  }
  
  static struct bpf_verifier_state_list **explored_state(
  					struct bpf_verifier_env *env,
  					int idx)
  {
  	struct bpf_verifier_state *cur = env->cur_state;
  	struct bpf_func_state *state = cur->frame[cur->curframe];
  
  	return &env->explored_states[(idx ^ state->callsite) % state_htab_size(env)];
  }
  
  static void init_explored_state(struct bpf_verifier_env *env, int idx)
  {
  	env->insn_aux_data[idx].prune_point = true;
  }
  
  enum {
  	DONE_EXPLORING = 0,
  	KEEP_EXPLORING = 1,
  };
  
  /* t, w, e - match pseudo-code above:
   * t - index of current instruction
   * w - next instruction
   * e - edge
   */
  static int push_insn(int t, int w, int e, struct bpf_verifier_env *env,
  		     bool loop_ok)
  {
  	int *insn_stack = env->cfg.insn_stack;
  	int *insn_state = env->cfg.insn_state;
  
  	if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
  		return DONE_EXPLORING;
  
  	if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH))
  		return DONE_EXPLORING;
  
  	if (w < 0 || w >= env->prog->len) {
  		verbose_linfo(env, t, "%d: ", t);
  		verbose(env, "jump out of range from insn %d to %d\n", t, w);
  		return -EINVAL;
  	}
  
  	if (e == BRANCH)
  		/* mark branch target for state pruning */
  		init_explored_state(env, w);
  
  	if (insn_state[w] == 0) {
  		/* tree-edge */
  		insn_state[t] = DISCOVERED | e;
  		insn_state[w] = DISCOVERED;
  		if (env->cfg.cur_stack >= env->prog->len)
  			return -E2BIG;
  		insn_stack[env->cfg.cur_stack++] = w;
  		return KEEP_EXPLORING;
  	} else if ((insn_state[w] & 0xF0) == DISCOVERED) {
  		if (loop_ok && env->bpf_capable)
  			return DONE_EXPLORING;
  		verbose_linfo(env, t, "%d: ", t);
  		verbose_linfo(env, w, "%d: ", w);
  		verbose(env, "back-edge from insn %d to %d\n", t, w);
  		return -EINVAL;
  	} else if (insn_state[w] == EXPLORED) {
  		/* forward- or cross-edge */
  		insn_state[t] = DISCOVERED | e;
  	} else {
  		verbose(env, "insn state internal bug\n");
  		return -EFAULT;
  	}
  	return DONE_EXPLORING;
  }
  
  static int visit_func_call_insn(int t, int insn_cnt,
  				struct bpf_insn *insns,
  				struct bpf_verifier_env *env,
  				bool visit_callee)
  {
  	int ret;
  
  	ret = push_insn(t, t + 1, FALLTHROUGH, env, false);
  	if (ret)
  		return ret;
  
  	if (t + 1 < insn_cnt)
  		init_explored_state(env, t + 1);
  	if (visit_callee) {
  		init_explored_state(env, t);
  		ret = push_insn(t, t + insns[t].imm + 1, BRANCH, env,
  				/* It's ok to allow recursion from CFG point of
  				 * view. __check_func_call() will do the actual
  				 * check.
  				 */
  				bpf_pseudo_func(insns + t));
  	}
  	return ret;
  }
  
  /* Visits the instruction at index t and returns one of the following:
   *  < 0 - an error occurred
   *  DONE_EXPLORING - the instruction was fully explored
   *  KEEP_EXPLORING - there is still work to be done before it is fully explored
   */
  static int visit_insn(int t, int insn_cnt, struct bpf_verifier_env *env)
  {
  	struct bpf_insn *insns = env->prog->insnsi;
  	int ret;
  
  	if (bpf_pseudo_func(insns + t))
  		return visit_func_call_insn(t, insn_cnt, insns, env, true);
  
  	/* All non-branch instructions have a single fall-through edge. */
  	if (BPF_CLASS(insns[t].code) != BPF_JMP &&
  	    BPF_CLASS(insns[t].code) != BPF_JMP32)
  		return push_insn(t, t + 1, FALLTHROUGH, env, false);
  
  	switch (BPF_OP(insns[t].code)) {
  	case BPF_EXIT:
  		return DONE_EXPLORING;
  
  	case BPF_CALL:
  		if (insns[t].imm == BPF_FUNC_timer_set_callback)
  			/* Mark this call insn to trigger is_state_visited() check
  			 * before call itself is processed by __check_func_call().
  			 * Otherwise new async state will be pushed for further
  			 * exploration.
  			 */
  			init_explored_state(env, t);
  		return visit_func_call_insn(t, insn_cnt, insns, env,
  					    insns[t].src_reg == BPF_PSEUDO_CALL);
  
  	case BPF_JA:
  		if (BPF_SRC(insns[t].code) != BPF_K)
  			return -EINVAL;
  
  		/* unconditional jump with single edge */
  		ret = push_insn(t, t + insns[t].off + 1, FALLTHROUGH, env,
  				true);
  		if (ret)
  			return ret;
  
  		/* unconditional jmp is not a good pruning point,
  		 * but it's marked, since backtracking needs
  		 * to record jmp history in is_state_visited().
  		 */
  		init_explored_state(env, t + insns[t].off + 1);
  		/* tell verifier to check for equivalent states
  		 * after every call and jump
  		 */
  		if (t + 1 < insn_cnt)
  			init_explored_state(env, t + 1);
  
  		return ret;
  
  	default:
  		/* conditional jump with two edges */
  		init_explored_state(env, t);
  		ret = push_insn(t, t + 1, FALLTHROUGH, env, true);
  		if (ret)
  			return ret;
  
  		return push_insn(t, t + insns[t].off + 1, BRANCH, env, true);
  	}
  }
  
  /* non-recursive depth-first-search to detect loops in BPF program
   * loop == back-edge in directed graph
   */
  static int check_cfg(struct bpf_verifier_env *env)
  {
  	int insn_cnt = env->prog->len;
  	int *insn_stack, *insn_state;
  	int ret = 0;
  	int i;
  
  	insn_state = env->cfg.insn_state = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
  	if (!insn_state)
  		return -ENOMEM;
  
  	insn_stack = env->cfg.insn_stack = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
  	if (!insn_stack) {
  		kvfree(insn_state);
  		return -ENOMEM;
  	}
  
  	insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
  	insn_stack[0] = 0; /* 0 is the first instruction */
  	env->cfg.cur_stack = 1;
  
  	while (env->cfg.cur_stack > 0) {
  		int t = insn_stack[env->cfg.cur_stack - 1];
  
  		ret = visit_insn(t, insn_cnt, env);
  		switch (ret) {
  		case DONE_EXPLORING:
  			insn_state[t] = EXPLORED;
  			env->cfg.cur_stack--;
  			break;
  		case KEEP_EXPLORING:
  			break;
  		default:
  			if (ret > 0) {
  				verbose(env, "visit_insn internal bug\n");
  				ret = -EFAULT;
  			}
  			goto err_free;
  		}
  	}
  
  	if (env->cfg.cur_stack < 0) {
  		verbose(env, "pop stack internal bug\n");
  		ret = -EFAULT;
  		goto err_free;
  	}
  
  	for (i = 0; i < insn_cnt; i++) {
  		if (insn_state[i] != EXPLORED) {
  			verbose(env, "unreachable insn %d\n", i);
  			ret = -EINVAL;
  			goto err_free;
  		}
  	}
  	ret = 0; /* cfg looks good */
  
  err_free:
  	kvfree(insn_state);
  	kvfree(insn_stack);
  	env->cfg.insn_state = env->cfg.insn_stack = NULL;
  	return ret;
  }
  
  static int check_abnormal_return(struct bpf_verifier_env *env)
  {
  	int i;
  
  	for (i = 1; i < env->subprog_cnt; i++) {
  		if (env->subprog_info[i].has_ld_abs) {
  			verbose(env, "LD_ABS is not allowed in subprogs without BTF\n");
  			return -EINVAL;
  		}
  		if (env->subprog_info[i].has_tail_call) {
  			verbose(env, "tail_call is not allowed in subprogs without BTF\n");
  			return -EINVAL;
  		}
  	}
  	return 0;
  }
  
  /* The minimum supported BTF func info size */
  #define MIN_BPF_FUNCINFO_SIZE	8
  #define MAX_FUNCINFO_REC_SIZE	252
  
  static int check_btf_func(struct bpf_verifier_env *env,
  			  const union bpf_attr *attr,
  			  bpfptr_t uattr)
  {
  	const struct btf_type *type, *func_proto, *ret_type;
  	u32 i, nfuncs, urec_size, min_size;
  	u32 krec_size = sizeof(struct bpf_func_info);
  	struct bpf_func_info *krecord;
  	struct bpf_func_info_aux *info_aux = NULL;
  	struct bpf_prog *prog;
  	const struct btf *btf;
  	bpfptr_t urecord;
  	u32 prev_offset = 0;
  	bool scalar_return;
  	int ret = -ENOMEM;
  
  	nfuncs = attr->func_info_cnt;
  	if (!nfuncs) {
  		if (check_abnormal_return(env))
  			return -EINVAL;
  		return 0;
  	}
  
  	if (nfuncs != env->subprog_cnt) {
  		verbose(env, "number of funcs in func_info doesn't match number of subprogs\n");
  		return -EINVAL;
  	}
  
  	urec_size = attr->func_info_rec_size;
  	if (urec_size < MIN_BPF_FUNCINFO_SIZE ||
  	    urec_size > MAX_FUNCINFO_REC_SIZE ||
  	    urec_size % sizeof(u32)) {
  		verbose(env, "invalid func info rec size %u\n", urec_size);
  		return -EINVAL;
  	}
  
  	prog = env->prog;
  	btf = prog->aux->btf;
  
  	urecord = make_bpfptr(attr->func_info, uattr.is_kernel);
  	min_size = min_t(u32, krec_size, urec_size);
  
  	krecord = kvcalloc(nfuncs, krec_size, GFP_KERNEL | __GFP_NOWARN);
  	if (!krecord)
  		return -ENOMEM;
  	info_aux = kcalloc(nfuncs, sizeof(*info_aux), GFP_KERNEL | __GFP_NOWARN);
  	if (!info_aux)
  		goto err_free;
  
  	for (i = 0; i < nfuncs; i++) {
  		ret = bpf_check_uarg_tail_zero(urecord, krec_size, urec_size);
  		if (ret) {
  			if (ret == -E2BIG) {
  				verbose(env, "nonzero tailing record in func info");
  				/* set the size kernel expects so loader can zero
  				 * out the rest of the record.
  				 */
  				if (copy_to_bpfptr_offset(uattr,
  							  offsetof(union bpf_attr, func_info_rec_size),
  							  &min_size, sizeof(min_size)))
  					ret = -EFAULT;
  			}
  			goto err_free;
  		}
  
  		if (copy_from_bpfptr(&krecord[i], urecord, min_size)) {
  			ret = -EFAULT;
  			goto err_free;
  		}
  
  		/* check insn_off */
  		ret = -EINVAL;
  		if (i == 0) {
  			if (krecord[i].insn_off) {
  				verbose(env,
  					"nonzero insn_off %u for the first func info record",
  					krecord[i].insn_off);
  				goto err_free;
  			}
  		} else if (krecord[i].insn_off <= prev_offset) {
  			verbose(env,
  				"same or smaller insn offset (%u) than previous func info record (%u)",
  				krecord[i].insn_off, prev_offset);
  			goto err_free;
  		}
  
  		if (env->subprog_info[i].start != krecord[i].insn_off) {
  			verbose(env, "func_info BTF section doesn't match subprog layout in BPF program\n");
  			goto err_free;
  		}
  
  		/* check type_id */
  		type = btf_type_by_id(btf, krecord[i].type_id);
  		if (!type || !btf_type_is_func(type)) {
  			verbose(env, "invalid type id %d in func info",
  				krecord[i].type_id);
  			goto err_free;
  		}
  		info_aux[i].linkage = BTF_INFO_VLEN(type->info);
  
  		func_proto = btf_type_by_id(btf, type->type);
  		if (unlikely(!func_proto || !btf_type_is_func_proto(func_proto)))
  			/* btf_func_check() already verified it during BTF load */
  			goto err_free;
  		ret_type = btf_type_skip_modifiers(btf, func_proto->type, NULL);
  		scalar_return =
  			btf_type_is_small_int(ret_type) || btf_type_is_enum(ret_type);
  		if (i && !scalar_return && env->subprog_info[i].has_ld_abs) {
  			verbose(env, "LD_ABS is only allowed in functions that return 'int'.\n");
  			goto err_free;
  		}
  		if (i && !scalar_return && env->subprog_info[i].has_tail_call) {
  			verbose(env, "tail_call is only allowed in functions that return 'int'.\n");
  			goto err_free;
  		}
  
  		prev_offset = krecord[i].insn_off;
  		bpfptr_add(&urecord, urec_size);
  	}
  
  	prog->aux->func_info = krecord;
  	prog->aux->func_info_cnt = nfuncs;
  	prog->aux->func_info_aux = info_aux;
  	return 0;
  
  err_free:
  	kvfree(krecord);
  	kfree(info_aux);
  	return ret;
  }
  
  static void adjust_btf_func(struct bpf_verifier_env *env)
  {
  	struct bpf_prog_aux *aux = env->prog->aux;
  	int i;
  
  	if (!aux->func_info)
  		return;
  
  	for (i = 0; i < env->subprog_cnt; i++)
  		aux->func_info[i].insn_off = env->subprog_info[i].start;
  }
  
  #define MIN_BPF_LINEINFO_SIZE	offsetofend(struct bpf_line_info, line_col)
  #define MAX_LINEINFO_REC_SIZE	MAX_FUNCINFO_REC_SIZE
  
  static int check_btf_line(struct bpf_verifier_env *env,
  			  const union bpf_attr *attr,
  			  bpfptr_t uattr)
  {
  	u32 i, s, nr_linfo, ncopy, expected_size, rec_size, prev_offset = 0;
  	struct bpf_subprog_info *sub;
  	struct bpf_line_info *linfo;
  	struct bpf_prog *prog;
  	const struct btf *btf;
  	bpfptr_t ulinfo;
  	int err;
  
  	nr_linfo = attr->line_info_cnt;
  	if (!nr_linfo)
  		return 0;
  	if (nr_linfo > INT_MAX / sizeof(struct bpf_line_info))
  		return -EINVAL;
  
  	rec_size = attr->line_info_rec_size;
  	if (rec_size < MIN_BPF_LINEINFO_SIZE ||
  	    rec_size > MAX_LINEINFO_REC_SIZE ||
  	    rec_size & (sizeof(u32) - 1))
  		return -EINVAL;
  
  	/* Need to zero it in case the userspace may
  	 * pass in a smaller bpf_line_info object.
  	 */
  	linfo = kvcalloc(nr_linfo, sizeof(struct bpf_line_info),
  			 GFP_KERNEL | __GFP_NOWARN);
  	if (!linfo)
  		return -ENOMEM;
  
  	prog = env->prog;
  	btf = prog->aux->btf;
  
  	s = 0;
  	sub = env->subprog_info;
  	ulinfo = make_bpfptr(attr->line_info, uattr.is_kernel);
  	expected_size = sizeof(struct bpf_line_info);
  	ncopy = min_t(u32, expected_size, rec_size);
  	for (i = 0; i < nr_linfo; i++) {
  		err = bpf_check_uarg_tail_zero(ulinfo, expected_size, rec_size);
  		if (err) {
  			if (err == -E2BIG) {
  				verbose(env, "nonzero tailing record in line_info");
  				if (copy_to_bpfptr_offset(uattr,
  							  offsetof(union bpf_attr, line_info_rec_size),
  							  &expected_size, sizeof(expected_size)))
  					err = -EFAULT;
  			}
  			goto err_free;
  		}
  
  		if (copy_from_bpfptr(&linfo[i], ulinfo, ncopy)) {
  			err = -EFAULT;
  			goto err_free;
  		}
  
  		/*
  		 * Check insn_off to ensure
  		 * 1) strictly increasing AND
  		 * 2) bounded by prog->len
  		 *
  		 * The linfo[0].insn_off == 0 check logically falls into
  		 * the later "missing bpf_line_info for func..." case
  		 * because the first linfo[0].insn_off must be the
  		 * first sub also and the first sub must have
  		 * subprog_info[0].start == 0.
  		 */
  		if ((i && linfo[i].insn_off <= prev_offset) ||
  		    linfo[i].insn_off >= prog->len) {
  			verbose(env, "Invalid line_info[%u].insn_off:%u (prev_offset:%u prog->len:%u)\n",
  				i, linfo[i].insn_off, prev_offset,
  				prog->len);
  			err = -EINVAL;
  			goto err_free;
  		}
  
  		if (!prog->insnsi[linfo[i].insn_off].code) {
  			verbose(env,
  				"Invalid insn code at line_info[%u].insn_off\n",
  				i);
  			err = -EINVAL;
  			goto err_free;
  		}
  
  		if (!btf_name_by_offset(btf, linfo[i].line_off) ||
  		    !btf_name_by_offset(btf, linfo[i].file_name_off)) {
  			verbose(env, "Invalid line_info[%u].line_off or .file_name_off\n", i);
  			err = -EINVAL;
  			goto err_free;
  		}
  
  		if (s != env->subprog_cnt) {
  			if (linfo[i].insn_off == sub[s].start) {
  				sub[s].linfo_idx = i;
  				s++;
  			} else if (sub[s].start < linfo[i].insn_off) {
  				verbose(env, "missing bpf_line_info for func#%u\n", s);
  				err = -EINVAL;
  				goto err_free;
  			}
  		}
  
  		prev_offset = linfo[i].insn_off;
  		bpfptr_add(&ulinfo, rec_size);
  	}
  
  	if (s != env->subprog_cnt) {
  		verbose(env, "missing bpf_line_info for %u funcs starting from func#%u\n",
  			env->subprog_cnt - s, s);
  		err = -EINVAL;
  		goto err_free;
  	}
  
  	prog->aux->linfo = linfo;
  	prog->aux->nr_linfo = nr_linfo;
  
  	return 0;
  
  err_free:
  	kvfree(linfo);
  	return err;
  }
  
  #define MIN_CORE_RELO_SIZE	sizeof(struct bpf_core_relo)
  #define MAX_CORE_RELO_SIZE	MAX_FUNCINFO_REC_SIZE
  
  static int check_core_relo(struct bpf_verifier_env *env,
  			   const union bpf_attr *attr,
  			   bpfptr_t uattr)
  {
  	u32 i, nr_core_relo, ncopy, expected_size, rec_size;
  	struct bpf_core_relo core_relo = {};
  	struct bpf_prog *prog = env->prog;
  	const struct btf *btf = prog->aux->btf;
  	struct bpf_core_ctx ctx = {
  		.log = &env->log,
  		.btf = btf,
  	};
  	bpfptr_t u_core_relo;
  	int err;
  
  	nr_core_relo = attr->core_relo_cnt;
  	if (!nr_core_relo)
  		return 0;
  	if (nr_core_relo > INT_MAX / sizeof(struct bpf_core_relo))
  		return -EINVAL;
  
  	rec_size = attr->core_relo_rec_size;
  	if (rec_size < MIN_CORE_RELO_SIZE ||
  	    rec_size > MAX_CORE_RELO_SIZE ||
  	    rec_size % sizeof(u32))
  		return -EINVAL;
  
  	u_core_relo = make_bpfptr(attr->core_relos, uattr.is_kernel);
  	expected_size = sizeof(struct bpf_core_relo);
  	ncopy = min_t(u32, expected_size, rec_size);
  
  	/* Unlike func_info and line_info, copy and apply each CO-RE
  	 * relocation record one at a time.
  	 */
  	for (i = 0; i < nr_core_relo; i++) {
  		/* future proofing when sizeof(bpf_core_relo) changes */
  		err = bpf_check_uarg_tail_zero(u_core_relo, expected_size, rec_size);
  		if (err) {
  			if (err == -E2BIG) {
  				verbose(env, "nonzero tailing record in core_relo");
  				if (copy_to_bpfptr_offset(uattr,
  							  offsetof(union bpf_attr, core_relo_rec_size),
  							  &expected_size, sizeof(expected_size)))
  					err = -EFAULT;
  			}
  			break;
  		}
  
  		if (copy_from_bpfptr(&core_relo, u_core_relo, ncopy)) {
  			err = -EFAULT;
  			break;
  		}
  
  		if (core_relo.insn_off % 8 || core_relo.insn_off / 8 >= prog->len) {
  			verbose(env, "Invalid core_relo[%u].insn_off:%u prog->len:%u\n",
  				i, core_relo.insn_off, prog->len);
  			err = -EINVAL;
  			break;
  		}
  
  		err = bpf_core_apply(&ctx, &core_relo, i,
  				     &prog->insnsi[core_relo.insn_off / 8]);
  		if (err)
  			break;
  		bpfptr_add(&u_core_relo, rec_size);
  	}
  	return err;
  }
  
  static int check_btf_info(struct bpf_verifier_env *env,
  			  const union bpf_attr *attr,
  			  bpfptr_t uattr)
  {
  	struct btf *btf;
  	int err;
  
  	if (!attr->func_info_cnt && !attr->line_info_cnt) {
  		if (check_abnormal_return(env))
  			return -EINVAL;
  		return 0;
  	}
  
  	btf = btf_get_by_fd(attr->prog_btf_fd);
  	if (IS_ERR(btf))
  		return PTR_ERR(btf);
  	if (btf_is_kernel(btf)) {
  		btf_put(btf);
  		return -EACCES;
  	}
  	env->prog->aux->btf = btf;
  
  	err = check_btf_func(env, attr, uattr);
  	if (err)
  		return err;
  
  	err = check_btf_line(env, attr, uattr);
  	if (err)
  		return err;
  
  	err = check_core_relo(env, attr, uattr);
  	if (err)
  		return err;
  
  	return 0;
  }
  
  /* check %cur's range satisfies %old's */
  static bool range_within(struct bpf_reg_state *old,
  			 struct bpf_reg_state *cur)
  {
  	return old->umin_value <= cur->umin_value &&
  	       old->umax_value >= cur->umax_value &&
  	       old->smin_value <= cur->smin_value &&
  	       old->smax_value >= cur->smax_value &&
  	       old->u32_min_value <= cur->u32_min_value &&
  	       old->u32_max_value >= cur->u32_max_value &&
  	       old->s32_min_value <= cur->s32_min_value &&
  	       old->s32_max_value >= cur->s32_max_value;
  }
  
  /* If in the old state two registers had the same id, then they need to have
   * the same id in the new state as well.  But that id could be different from
   * the old state, so we need to track the mapping from old to new ids.
   * Once we have seen that, say, a reg with old id 5 had new id 9, any subsequent
   * regs with old id 5 must also have new id 9 for the new state to be safe.  But
   * regs with a different old id could still have new id 9, we don't care about
   * that.
   * So we look through our idmap to see if this old id has been seen before.  If
   * so, we require the new id to match; otherwise, we add the id pair to the map.
   */
  static bool check_ids(u32 old_id, u32 cur_id, struct bpf_id_pair *idmap)
  {
  	unsigned int i;
  
  	for (i = 0; i < BPF_ID_MAP_SIZE; i++) {
  		if (!idmap[i].old) {
  			/* Reached an empty slot; haven't seen this id before */
  			idmap[i].old = old_id;
  			idmap[i].cur = cur_id;
  			return true;
  		}
  		if (idmap[i].old == old_id)
  			return idmap[i].cur == cur_id;
  	}
  	/* We ran out of idmap slots, which should be impossible */
  	WARN_ON_ONCE(1);
  	return false;
  }
  
  static void clean_func_state(struct bpf_verifier_env *env,
  			     struct bpf_func_state *st)
  {
  	enum bpf_reg_liveness live;
  	int i, j;
  
  	for (i = 0; i < BPF_REG_FP; i++) {
  		live = st->regs[i].live;
  		/* liveness must not touch this register anymore */
  		st->regs[i].live |= REG_LIVE_DONE;
  		if (!(live & REG_LIVE_READ))
  			/* since the register is unused, clear its state
  			 * to make further comparison simpler
  			 */
  			__mark_reg_not_init(env, &st->regs[i]);
  	}
  
  	for (i = 0; i < st->allocated_stack / BPF_REG_SIZE; i++) {
  		live = st->stack[i].spilled_ptr.live;
  		/* liveness must not touch this stack slot anymore */
  		st->stack[i].spilled_ptr.live |= REG_LIVE_DONE;
  		if (!(live & REG_LIVE_READ)) {
  			__mark_reg_not_init(env, &st->stack[i].spilled_ptr);
  			for (j = 0; j < BPF_REG_SIZE; j++)
  				st->stack[i].slot_type[j] = STACK_INVALID;
  		}
  	}
  }
  
  static void clean_verifier_state(struct bpf_verifier_env *env,
  				 struct bpf_verifier_state *st)
  {
  	int i;
  
  	if (st->frame[0]->regs[0].live & REG_LIVE_DONE)
  		/* all regs in this state in all frames were already marked */
  		return;
  
  	for (i = 0; i <= st->curframe; i++)
  		clean_func_state(env, st->frame[i]);
  }
  
  /* the parentage chains form a tree.
   * the verifier states are added to state lists at given insn and
   * pushed into state stack for future exploration.
   * when the verifier reaches bpf_exit insn some of the verifer states
   * stored in the state lists have their final liveness state already,
   * but a lot of states will get revised from liveness point of view when
   * the verifier explores other branches.
   * Example:
   * 1: r0 = 1
   * 2: if r1 == 100 goto pc+1
   * 3: r0 = 2
   * 4: exit
   * when the verifier reaches exit insn the register r0 in the state list of
   * insn 2 will be seen as !REG_LIVE_READ. Then the verifier pops the other_branch
   * of insn 2 and goes exploring further. At the insn 4 it will walk the
   * parentage chain from insn 4 into insn 2 and will mark r0 as REG_LIVE_READ.
   *
   * Since the verifier pushes the branch states as it sees them while exploring
   * the program the condition of walking the branch instruction for the second
   * time means that all states below this branch were already explored and
   * their final liveness marks are already propagated.
   * Hence when the verifier completes the search of state list in is_state_visited()
   * we can call this clean_live_states() function to mark all liveness states
   * as REG_LIVE_DONE to indicate that 'parent' pointers of 'struct bpf_reg_state'
   * will not be used.
   * This function also clears the registers and stack for states that !READ
   * to simplify state merging.
   *
   * Important note here that walking the same branch instruction in the callee
   * doesn't meant that the states are DONE. The verifier has to compare
   * the callsites
   */
  static void clean_live_states(struct bpf_verifier_env *env, int insn,
  			      struct bpf_verifier_state *cur)
  {
  	struct bpf_verifier_state_list *sl;
  	int i;
  
  	sl = *explored_state(env, insn);
  	while (sl) {
  		if (sl->state.branches)
  			goto next;
  		if (sl->state.insn_idx != insn ||
  		    sl->state.curframe != cur->curframe)
  			goto next;
  		for (i = 0; i <= cur->curframe; i++)
  			if (sl->state.frame[i]->callsite != cur->frame[i]->callsite)
  				goto next;
  		clean_verifier_state(env, &sl->state);
  next:
  		sl = sl->next;
  	}
  }
  
  /* Returns true if (rold safe implies rcur safe) */
  static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold,
  		    struct bpf_reg_state *rcur, struct bpf_id_pair *idmap)
  {
  	bool equal;
  
  	if (!(rold->live & REG_LIVE_READ))
  		/* explored state didn't use this */
  		return true;
  
  	equal = memcmp(rold, rcur, offsetof(struct bpf_reg_state, parent)) == 0;
  
  	if (rold->type == PTR_TO_STACK)
  		/* two stack pointers are equal only if they're pointing to
  		 * the same stack frame, since fp-8 in foo != fp-8 in bar
  		 */
  		return equal && rold->frameno == rcur->frameno;
  
  	if (equal)
  		return true;
  
  	if (rold->type == NOT_INIT)
  		/* explored state can't have used this */
  		return true;
  	if (rcur->type == NOT_INIT)
  		return false;
  	switch (base_type(rold->type)) {
  	case SCALAR_VALUE:
  		if (env->explore_alu_limits)
  			return false;
  		if (rcur->type == SCALAR_VALUE) {
  			if (!rold->precise && !rcur->precise)
  				return true;
  			/* new val must satisfy old val knowledge */
  			return range_within(rold, rcur) &&
  			       tnum_in(rold->var_off, rcur->var_off);
  		} else {
  			/* We're trying to use a pointer in place of a scalar.
  			 * Even if the scalar was unbounded, this could lead to
  			 * pointer leaks because scalars are allowed to leak
  			 * while pointers are not. We could make this safe in
  			 * special cases if root is calling us, but it's
  			 * probably not worth the hassle.
  			 */
  			return false;
  		}
  	case PTR_TO_MAP_KEY:
  	case PTR_TO_MAP_VALUE:
  		/* a PTR_TO_MAP_VALUE could be safe to use as a
  		 * PTR_TO_MAP_VALUE_OR_NULL into the same map.
  		 * However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL-
  		 * checked, doing so could have affected others with the same
  		 * id, and we can't check for that because we lost the id when
  		 * we converted to a PTR_TO_MAP_VALUE.
  		 */
  		if (type_may_be_null(rold->type)) {
  			if (!type_may_be_null(rcur->type))
  				return false;
  			if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)))
  				return false;
  			/* Check our ids match any regs they're supposed to */
  			return check_ids(rold->id, rcur->id, idmap);
  		}
  
  		/* If the new min/max/var_off satisfy the old ones and
  		 * everything else matches, we are OK.
  		 * 'id' is not compared, since it's only used for maps with
  		 * bpf_spin_lock inside map element and in such cases if
  		 * the rest of the prog is valid for one map element then
  		 * it's valid for all map elements regardless of the key
  		 * used in bpf_map_lookup()
  		 */
  		return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 &&
  		       range_within(rold, rcur) &&
  		       tnum_in(rold->var_off, rcur->var_off);
  	case PTR_TO_PACKET_META:
  	case PTR_TO_PACKET:
  		if (rcur->type != rold->type)
  			return false;
  		/* We must have at least as much range as the old ptr
  		 * did, so that any accesses which were safe before are
  		 * still safe.  This is true even if old range < old off,
  		 * since someone could have accessed through (ptr - k), or
  		 * even done ptr -= k in a register, to get a safe access.
  		 */
  		if (rold->range > rcur->range)
  			return false;
  		/* If the offsets don't match, we can't trust our alignment;
  		 * nor can we be sure that we won't fall out of range.
  		 */
  		if (rold->off != rcur->off)
  			return false;
  		/* id relations must be preserved */
  		if (rold->id && !check_ids(rold->id, rcur->id, idmap))
  			return false;
  		/* new val must satisfy old val knowledge */
  		return range_within(rold, rcur) &&
  		       tnum_in(rold->var_off, rcur->var_off);
  	case PTR_TO_CTX:
  	case CONST_PTR_TO_MAP:
  	case PTR_TO_PACKET_END:
  	case PTR_TO_FLOW_KEYS:
  	case PTR_TO_SOCKET:
  	case PTR_TO_SOCK_COMMON:
  	case PTR_TO_TCP_SOCK:
  	case PTR_TO_XDP_SOCK:
  		/* Only valid matches are exact, which memcmp() above
  		 * would have accepted
  		 */
  	default:
  		/* Don't know what's going on, just say it's not safe */
  		return false;
  	}
  
  	/* Shouldn't get here; if we do, say it's not safe */
  	WARN_ON_ONCE(1);
  	return false;
  }
  
  static bool stacksafe(struct bpf_verifier_env *env, struct bpf_func_state *old,
  		      struct bpf_func_state *cur, struct bpf_id_pair *idmap)
  {
  	int i, spi;
  
  	/* walk slots of the explored stack and ignore any additional
  	 * slots in the current stack, since explored(safe) state
  	 * didn't use them
  	 */
  	for (i = 0; i < old->allocated_stack; i++) {
  		spi = i / BPF_REG_SIZE;
  
  		if (!(old->stack[spi].spilled_ptr.live & REG_LIVE_READ)) {
  			i += BPF_REG_SIZE - 1;
  			/* explored state didn't use this */
  			continue;
  		}
  
  		if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_INVALID)
  			continue;
  
  		/* explored stack has more populated slots than current stack
  		 * and these slots were used
  		 */
  		if (i >= cur->allocated_stack)
  			return false;
  
  		/* if old state was safe with misc data in the stack
  		 * it will be safe with zero-initialized stack.
  		 * The opposite is not true
  		 */
  		if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_MISC &&
  		    cur->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_ZERO)
  			continue;
  		if (old->stack[spi].slot_type[i % BPF_REG_SIZE] !=
  		    cur->stack[spi].slot_type[i % BPF_REG_SIZE])
  			/* Ex: old explored (safe) state has STACK_SPILL in
  			 * this stack slot, but current has STACK_MISC ->
  			 * this verifier states are not equivalent,
  			 * return false to continue verification of this path
  			 */
  			return false;
  		if (i % BPF_REG_SIZE != BPF_REG_SIZE - 1)
  			continue;
  		if (!is_spilled_reg(&old->stack[spi]))
  			continue;
  		if (!regsafe(env, &old->stack[spi].spilled_ptr,
  			     &cur->stack[spi].spilled_ptr, idmap))
  			/* when explored and current stack slot are both storing
  			 * spilled registers, check that stored pointers types
  			 * are the same as well.
  			 * Ex: explored safe path could have stored
  			 * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8}
  			 * but current path has stored:
  			 * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16}
  			 * such verifier states are not equivalent.
  			 * return false to continue verification of this path
  			 */
  			return false;
  	}
  	return true;
  }
  
  static bool refsafe(struct bpf_func_state *old, struct bpf_func_state *cur)
  {
  	if (old->acquired_refs != cur->acquired_refs)
  		return false;
  	return !memcmp(old->refs, cur->refs,
  		       sizeof(*old->refs) * old->acquired_refs);
  }
  
  /* compare two verifier states
   *
   * all states stored in state_list are known to be valid, since
   * verifier reached 'bpf_exit' instruction through them
   *
   * this function is called when verifier exploring different branches of
   * execution popped from the state stack. If it sees an old state that has
   * more strict register state and more strict stack state then this execution
   * branch doesn't need to be explored further, since verifier already
   * concluded that more strict state leads to valid finish.
   *
   * Therefore two states are equivalent if register state is more conservative
   * and explored stack state is more conservative than the current one.
   * Example:
   *       explored                   current
   * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
   * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
   *
   * In other words if current stack state (one being explored) has more
   * valid slots than old one that already passed validation, it means
   * the verifier can stop exploring and conclude that current state is valid too
   *
   * Similarly with registers. If explored state has register type as invalid
   * whereas register type in current state is meaningful, it means that
   * the current state will reach 'bpf_exit' instruction safely
   */
  static bool func_states_equal(struct bpf_verifier_env *env, struct bpf_func_state *old,
  			      struct bpf_func_state *cur)
  {
  	int i;
  
  	memset(env->idmap_scratch, 0, sizeof(env->idmap_scratch));
  	for (i = 0; i < MAX_BPF_REG; i++)
  		if (!regsafe(env, &old->regs[i], &cur->regs[i],
  			     env->idmap_scratch))
  			return false;
  
  	if (!stacksafe(env, old, cur, env->idmap_scratch))
  		return false;
  
  	if (!refsafe(old, cur))
  		return false;
  
  	return true;
  }
  
  static bool states_equal(struct bpf_verifier_env *env,
  			 struct bpf_verifier_state *old,
  			 struct bpf_verifier_state *cur)
  {
  	int i;
  
  	if (old->curframe != cur->curframe)
  		return false;
  
  	/* Verification state from speculative execution simulation
  	 * must never prune a non-speculative execution one.
  	 */
  	if (old->speculative && !cur->speculative)
  		return false;
  
  	if (old->active_spin_lock != cur->active_spin_lock)
  		return false;
  
  	/* for states to be equal callsites have to be the same
  	 * and all frame states need to be equivalent
  	 */
  	for (i = 0; i <= old->curframe; i++) {
  		if (old->frame[i]->callsite != cur->frame[i]->callsite)
  			return false;
  		if (!func_states_equal(env, old->frame[i], cur->frame[i]))
  			return false;
  	}
  	return true;
  }
  
  /* Return 0 if no propagation happened. Return negative error code if error
   * happened. Otherwise, return the propagated bit.
   */
  static int propagate_liveness_reg(struct bpf_verifier_env *env,
  				  struct bpf_reg_state *reg,
  				  struct bpf_reg_state *parent_reg)
  {
  	u8 parent_flag = parent_reg->live & REG_LIVE_READ;
  	u8 flag = reg->live & REG_LIVE_READ;
  	int err;
  
  	/* When comes here, read flags of PARENT_REG or REG could be any of
  	 * REG_LIVE_READ64, REG_LIVE_READ32, REG_LIVE_NONE. There is no need
  	 * of propagation if PARENT_REG has strongest REG_LIVE_READ64.
  	 */
  	if (parent_flag == REG_LIVE_READ64 ||
  	    /* Or if there is no read flag from REG. */
  	    !flag ||
  	    /* Or if the read flag from REG is the same as PARENT_REG. */
  	    parent_flag == flag)
  		return 0;
  
  	err = mark_reg_read(env, reg, parent_reg, flag);
  	if (err)
  		return err;
  
  	return flag;
  }
  
  /* A write screens off any subsequent reads; but write marks come from the
   * straight-line code between a state and its parent.  When we arrive at an
   * equivalent state (jump target or such) we didn't arrive by the straight-line
   * code, so read marks in the state must propagate to the parent regardless
   * of the state's write marks. That's what 'parent == state->parent' comparison
   * in mark_reg_read() is for.
   */
  static int propagate_liveness(struct bpf_verifier_env *env,
  			      const struct bpf_verifier_state *vstate,
  			      struct bpf_verifier_state *vparent)
  {
  	struct bpf_reg_state *state_reg, *parent_reg;
  	struct bpf_func_state *state, *parent;
  	int i, frame, err = 0;
  
  	if (vparent->curframe != vstate->curframe) {
  		WARN(1, "propagate_live: parent frame %d current frame %d\n",
  		     vparent->curframe, vstate->curframe);
  		return -EFAULT;
  	}
  	/* Propagate read liveness of registers... */
  	BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG);
  	for (frame = 0; frame <= vstate->curframe; frame++) {
  		parent = vparent->frame[frame];
  		state = vstate->frame[frame];
  		parent_reg = parent->regs;
  		state_reg = state->regs;
  		/* We don't need to worry about FP liveness, it's read-only */
  		for (i = frame < vstate->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++) {
  			err = propagate_liveness_reg(env, &state_reg[i],
  						     &parent_reg[i]);
  			if (err < 0)
  				return err;
  			if (err == REG_LIVE_READ64)
  				mark_insn_zext(env, &parent_reg[i]);
  		}
  
  		/* Propagate stack slots. */
  		for (i = 0; i < state->allocated_stack / BPF_REG_SIZE &&
  			    i < parent->allocated_stack / BPF_REG_SIZE; i++) {
  			parent_reg = &parent->stack[i].spilled_ptr;
  			state_reg = &state->stack[i].spilled_ptr;
  			err = propagate_liveness_reg(env, state_reg,
  						     parent_reg);
  			if (err < 0)
  				return err;
  		}
  	}
  	return 0;
  }
  
  /* find precise scalars in the previous equivalent state and
   * propagate them into the current state
   */
  static int propagate_precision(struct bpf_verifier_env *env,
  			       const struct bpf_verifier_state *old)
  {
  	struct bpf_reg_state *state_reg;
  	struct bpf_func_state *state;
  	int i, err = 0;
  
  	state = old->frame[old->curframe];
  	state_reg = state->regs;
  	for (i = 0; i < BPF_REG_FP; i++, state_reg++) {
  		if (state_reg->type != SCALAR_VALUE ||
  		    !state_reg->precise)
  			continue;
  		if (env->log.level & BPF_LOG_LEVEL2)
  			verbose(env, "propagating r%d\n", i);
  		err = mark_chain_precision(env, i);
  		if (err < 0)
  			return err;
  	}
  
  	for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
  		if (!is_spilled_reg(&state->stack[i]))
  			continue;
  		state_reg = &state->stack[i].spilled_ptr;
  		if (state_reg->type != SCALAR_VALUE ||
  		    !state_reg->precise)
  			continue;
  		if (env->log.level & BPF_LOG_LEVEL2)
  			verbose(env, "propagating fp%d\n",
  				(-i - 1) * BPF_REG_SIZE);
  		err = mark_chain_precision_stack(env, i);
  		if (err < 0)
  			return err;
  	}
  	return 0;
  }
  
  static bool states_maybe_looping(struct bpf_verifier_state *old,
  				 struct bpf_verifier_state *cur)
  {
  	struct bpf_func_state *fold, *fcur;
  	int i, fr = cur->curframe;
  
  	if (old->curframe != fr)
  		return false;
  
  	fold = old->frame[fr];
  	fcur = cur->frame[fr];
  	for (i = 0; i < MAX_BPF_REG; i++)
  		if (memcmp(&fold->regs[i], &fcur->regs[i],
  			   offsetof(struct bpf_reg_state, parent)))
  			return false;
  	return true;
  }
  
  
  static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
  {
  	struct bpf_verifier_state_list *new_sl;
  	struct bpf_verifier_state_list *sl, **pprev;
  	struct bpf_verifier_state *cur = env->cur_state, *new;
  	int i, j, err, states_cnt = 0;
  	bool add_new_state = env->test_state_freq ? true : false;
  
  	cur->last_insn_idx = env->prev_insn_idx;
  	if (!env->insn_aux_data[insn_idx].prune_point)
  		/* this 'insn_idx' instruction wasn't marked, so we will not
  		 * be doing state search here
  		 */
  		return 0;
  
  	/* bpf progs typically have pruning point every 4 instructions
  	 * http://vger.kernel.org/bpfconf2019.html#session-1
  	 * Do not add new state for future pruning if the verifier hasn't seen
  	 * at least 2 jumps and at least 8 instructions.
  	 * This heuristics helps decrease 'total_states' and 'peak_states' metric.
  	 * In tests that amounts to up to 50% reduction into total verifier
  	 * memory consumption and 20% verifier time speedup.
  	 */
  	if (env->jmps_processed - env->prev_jmps_processed >= 2 &&
  	    env->insn_processed - env->prev_insn_processed >= 8)
  		add_new_state = true;
  
  	pprev = explored_state(env, insn_idx);
  	sl = *pprev;
  
  	clean_live_states(env, insn_idx, cur);
  
  	while (sl) {
  		states_cnt++;
  		if (sl->state.insn_idx != insn_idx)
  			goto next;
  
  		if (sl->state.branches) {
  			struct bpf_func_state *frame = sl->state.frame[sl->state.curframe];
  
  			if (frame->in_async_callback_fn &&
  			    frame->async_entry_cnt != cur->frame[cur->curframe]->async_entry_cnt) {
  				/* Different async_entry_cnt means that the verifier is
  				 * processing another entry into async callback.
  				 * Seeing the same state is not an indication of infinite
  				 * loop or infinite recursion.
  				 * But finding the same state doesn't mean that it's safe
  				 * to stop processing the current state. The previous state
  				 * hasn't yet reached bpf_exit, since state.branches > 0.
  				 * Checking in_async_callback_fn alone is not enough either.
  				 * Since the verifier still needs to catch infinite loops
  				 * inside async callbacks.
  				 */
  			} else if (states_maybe_looping(&sl->state, cur) &&
  				   states_equal(env, &sl->state, cur)) {
  				verbose_linfo(env, insn_idx, "; ");
  				verbose(env, "infinite loop detected at insn %d\n", insn_idx);
  				return -EINVAL;
  			}
  			/* if the verifier is processing a loop, avoid adding new state
  			 * too often, since different loop iterations have distinct
  			 * states and may not help future pruning.
  			 * This threshold shouldn't be too low to make sure that
  			 * a loop with large bound will be rejected quickly.
  			 * The most abusive loop will be:
  			 * r1 += 1
  			 * if r1 < 1000000 goto pc-2
  			 * 1M insn_procssed limit / 100 == 10k peak states.
  			 * This threshold shouldn't be too high either, since states
  			 * at the end of the loop are likely to be useful in pruning.
  			 */
  			if (env->jmps_processed - env->prev_jmps_processed < 20 &&
  			    env->insn_processed - env->prev_insn_processed < 100)
  				add_new_state = false;
  			goto miss;
  		}
  		if (states_equal(env, &sl->state, cur)) {
  			sl->hit_cnt++;
  			/* reached equivalent register/stack state,
  			 * prune the search.
  			 * Registers read by the continuation are read by us.
  			 * If we have any write marks in env->cur_state, they
  			 * will prevent corresponding reads in the continuation
  			 * from reaching our parent (an explored_state).  Our
  			 * own state will get the read marks recorded, but
  			 * they'll be immediately forgotten as we're pruning
  			 * this state and will pop a new one.
  			 */
  			err = propagate_liveness(env, &sl->state, cur);
  
  			/* if previous state reached the exit with precision and
  			 * current state is equivalent to it (except precsion marks)
  			 * the precision needs to be propagated back in
  			 * the current state.
  			 */
  			err = err ? : push_jmp_history(env, cur);
  			err = err ? : propagate_precision(env, &sl->state);
  			if (err)
  				return err;
  			return 1;
  		}
  miss:
  		/* when new state is not going to be added do not increase miss count.
  		 * Otherwise several loop iterations will remove the state
  		 * recorded earlier. The goal of these heuristics is to have
  		 * states from some iterations of the loop (some in the beginning
  		 * and some at the end) to help pruning.
  		 */
  		if (add_new_state)
  			sl->miss_cnt++;
  		/* heuristic to determine whether this state is beneficial
  		 * to keep checking from state equivalence point of view.
  		 * Higher numbers increase max_states_per_insn and verification time,
  		 * but do not meaningfully decrease insn_processed.
  		 */
  		if (sl->miss_cnt > sl->hit_cnt * 3 + 3) {
  			/* the state is unlikely to be useful. Remove it to
  			 * speed up verification
  			 */
  			*pprev = sl->next;
  			if (sl->state.frame[0]->regs[0].live & REG_LIVE_DONE) {
  				u32 br = sl->state.branches;
  
  				WARN_ONCE(br,
  					  "BUG live_done but branches_to_explore %d\n",
  					  br);
  				free_verifier_state(&sl->state, false);
  				kfree(sl);
  				env->peak_states--;
  			} else {
  				/* cannot free this state, since parentage chain may
  				 * walk it later. Add it for free_list instead to
  				 * be freed at the end of verification
  				 */
  				sl->next = env->free_list;
  				env->free_list = sl;
  			}
  			sl = *pprev;
  			continue;
  		}
  next:
  		pprev = &sl->next;
  		sl = *pprev;
  	}
  
  	if (env->max_states_per_insn < states_cnt)
  		env->max_states_per_insn = states_cnt;
  
  	if (!env->bpf_capable && states_cnt > BPF_COMPLEXITY_LIMIT_STATES)
  		return push_jmp_history(env, cur);
  
  	if (!add_new_state)
  		return push_jmp_history(env, cur);
  
  	/* There were no equivalent states, remember the current one.
  	 * Technically the current state is not proven to be safe yet,
  	 * but it will either reach outer most bpf_exit (which means it's safe)
  	 * or it will be rejected. When there are no loops the verifier won't be
  	 * seeing this tuple (frame[0].callsite, frame[1].callsite, .. insn_idx)
  	 * again on the way to bpf_exit.
  	 * When looping the sl->state.branches will be > 0 and this state
  	 * will not be considered for equivalence until branches == 0.
  	 */
  	new_sl = kzalloc(sizeof(struct bpf_verifier_state_list), GFP_KERNEL);
  	if (!new_sl)
  		return -ENOMEM;
  	env->total_states++;
  	env->peak_states++;
  	env->prev_jmps_processed = env->jmps_processed;
  	env->prev_insn_processed = env->insn_processed;
  
  	/* add new state to the head of linked list */
  	new = &new_sl->state;
  	err = copy_verifier_state(new, cur);
  	if (err) {
  		free_verifier_state(new, false);
  		kfree(new_sl);
  		return err;
  	}
  	new->insn_idx = insn_idx;
  	WARN_ONCE(new->branches != 1,
  		  "BUG is_state_visited:branches_to_explore=%d insn %d\n", new->branches, insn_idx);
  
  	cur->parent = new;
  	cur->first_insn_idx = insn_idx;
  	clear_jmp_history(cur);
  	new_sl->next = *explored_state(env, insn_idx);
  	*explored_state(env, insn_idx) = new_sl;
  	/* connect new state to parentage chain. Current frame needs all
  	 * registers connected. Only r6 - r9 of the callers are alive (pushed
  	 * to the stack implicitly by JITs) so in callers' frames connect just
  	 * r6 - r9 as an optimization. Callers will have r1 - r5 connected to
  	 * the state of the call instruction (with WRITTEN set), and r0 comes
  	 * from callee with its full parentage chain, anyway.
  	 */
  	/* clear write marks in current state: the writes we did are not writes
  	 * our child did, so they don't screen off its reads from us.
  	 * (There are no read marks in current state, because reads always mark
  	 * their parent and current state never has children yet.  Only
  	 * explored_states can get read marks.)
  	 */
  	for (j = 0; j <= cur->curframe; j++) {
  		for (i = j < cur->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++)
  			cur->frame[j]->regs[i].parent = &new->frame[j]->regs[i];
  		for (i = 0; i < BPF_REG_FP; i++)
  			cur->frame[j]->regs[i].live = REG_LIVE_NONE;
  	}
  
  	/* all stack frames are accessible from callee, clear them all */
  	for (j = 0; j <= cur->curframe; j++) {
  		struct bpf_func_state *frame = cur->frame[j];
  		struct bpf_func_state *newframe = new->frame[j];
  
  		for (i = 0; i < frame->allocated_stack / BPF_REG_SIZE; i++) {
  			frame->stack[i].spilled_ptr.live = REG_LIVE_NONE;
  			frame->stack[i].spilled_ptr.parent =
  						&newframe->stack[i].spilled_ptr;
  		}
  	}
  	return 0;
  }
  
  /* Return true if it's OK to have the same insn return a different type. */
  static bool reg_type_mismatch_ok(enum bpf_reg_type type)
  {
  	switch (base_type(type)) {
  	case PTR_TO_CTX:
  	case PTR_TO_SOCKET:
  	case PTR_TO_SOCK_COMMON:
  	case PTR_TO_TCP_SOCK:
  	case PTR_TO_XDP_SOCK:
  	case PTR_TO_BTF_ID:
  		return false;
  	default:
  		return true;
  	}
  }
  
  /* If an instruction was previously used with particular pointer types, then we
   * need to be careful to avoid cases such as the below, where it may be ok
   * for one branch accessing the pointer, but not ok for the other branch:
   *
   * R1 = sock_ptr
   * goto X;
   * ...
   * R1 = some_other_valid_ptr;
   * goto X;
   * ...
   * R2 = *(u32 *)(R1 + 0);
   */
  static bool reg_type_mismatch(enum bpf_reg_type src, enum bpf_reg_type prev)
  {
  	return src != prev && (!reg_type_mismatch_ok(src) ||
  			       !reg_type_mismatch_ok(prev));
  }
  
  static int do_check(struct bpf_verifier_env *env)
  {
  	bool pop_log = !(env->log.level & BPF_LOG_LEVEL2);
  	struct bpf_verifier_state *state = env->cur_state;
  	struct bpf_insn *insns = env->prog->insnsi;
  	struct bpf_reg_state *regs;
  	int insn_cnt = env->prog->len;
  	bool do_print_state = false;
  	int prev_insn_idx = -1;
  
  	for (;;) {
  		struct bpf_insn *insn;
  		u8 class;
  		int err;
  
  		env->prev_insn_idx = prev_insn_idx;
  		if (env->insn_idx >= insn_cnt) {
  			verbose(env, "invalid insn idx %d insn_cnt %d\n",
  				env->insn_idx, insn_cnt);
  			return -EFAULT;
  		}
  
  		insn = &insns[env->insn_idx];
  		class = BPF_CLASS(insn->code);
  
  		if (++env->insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) {
  			verbose(env,
  				"BPF program is too large. Processed %d insn\n",
  				env->insn_processed);
  			return -E2BIG;
  		}
  
  		err = is_state_visited(env, env->insn_idx);
  		if (err < 0)
  			return err;
  		if (err == 1) {
  			/* found equivalent state, can prune the search */
  			if (env->log.level & BPF_LOG_LEVEL) {
  				if (do_print_state)
  					verbose(env, "\nfrom %d to %d%s: safe\n",
  						env->prev_insn_idx, env->insn_idx,
  						env->cur_state->speculative ?
  						" (speculative execution)" : "");
  				else
  					verbose(env, "%d: safe\n", env->insn_idx);
  			}
  			goto process_bpf_exit;
  		}
  
  		if (signal_pending(current))
  			return -EAGAIN;
  
  		if (need_resched())
  			cond_resched();
  
  		if (env->log.level & BPF_LOG_LEVEL2 && do_print_state) {
  			verbose(env, "\nfrom %d to %d%s:",
  				env->prev_insn_idx, env->insn_idx,
  				env->cur_state->speculative ?
  				" (speculative execution)" : "");
  			print_verifier_state(env, state->frame[state->curframe], true);
  			do_print_state = false;
  		}
  
  		if (env->log.level & BPF_LOG_LEVEL) {
  			const struct bpf_insn_cbs cbs = {
  				.cb_call	= disasm_kfunc_name,
  				.cb_print	= verbose,
  				.private_data	= env,
  			};
  
  			if (verifier_state_scratched(env))
  				print_insn_state(env, state->frame[state->curframe]);
  
  			verbose_linfo(env, env->insn_idx, "; ");
  			env->prev_log_len = env->log.len_used;
  			verbose(env, "%d: ", env->insn_idx);
  			print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
  			env->prev_insn_print_len = env->log.len_used - env->prev_log_len;
  			env->prev_log_len = env->log.len_used;
  		}
  
  		if (bpf_prog_is_dev_bound(env->prog->aux)) {
  			err = bpf_prog_offload_verify_insn(env, env->insn_idx,
  							   env->prev_insn_idx);
  			if (err)
  				return err;
  		}
  
  		regs = cur_regs(env);
  		sanitize_mark_insn_seen(env);
  		prev_insn_idx = env->insn_idx;
  
  		if (class == BPF_ALU || class == BPF_ALU64) {
  			err = check_alu_op(env, insn);
  			if (err)
  				return err;
  
  		} else if (class == BPF_LDX) {
  			enum bpf_reg_type *prev_src_type, src_reg_type;
  
  			/* check for reserved fields is already done */
  
  			/* check src operand */
  			err = check_reg_arg(env, insn->src_reg, SRC_OP);
  			if (err)
  				return err;
  
  			err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
  			if (err)
  				return err;
  
  			src_reg_type = regs[insn->src_reg].type;
  
  			/* check that memory (src_reg + off) is readable,
  			 * the state of dst_reg will be updated by this func
  			 */
  			err = check_mem_access(env, env->insn_idx, insn->src_reg,
  					       insn->off, BPF_SIZE(insn->code),
  					       BPF_READ, insn->dst_reg, false);
  			if (err)
  				return err;
  
  			prev_src_type = &env->insn_aux_data[env->insn_idx].ptr_type;
  
  			if (*prev_src_type == NOT_INIT) {
  				/* saw a valid insn
  				 * dst_reg = *(u32 *)(src_reg + off)
  				 * save type to validate intersecting paths
  				 */
  				*prev_src_type = src_reg_type;
  
  			} else if (reg_type_mismatch(src_reg_type, *prev_src_type)) {
  				/* ABuser program is trying to use the same insn
  				 * dst_reg = *(u32*) (src_reg + off)
  				 * with different pointer types:
  				 * src_reg == ctx in one branch and
  				 * src_reg == stack|map in some other branch.
  				 * Reject it.
  				 */
  				verbose(env, "same insn cannot be used with different pointers\n");
  				return -EINVAL;
  			}
  
  		} else if (class == BPF_STX) {
  			enum bpf_reg_type *prev_dst_type, dst_reg_type;
  
  			if (BPF_MODE(insn->code) == BPF_ATOMIC) {
  				err = check_atomic(env, env->insn_idx, insn);
  				if (err)
  					return err;
  				env->insn_idx++;
  				continue;
  			}
  
  			if (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0) {
  				verbose(env, "BPF_STX uses reserved fields\n");
  				return -EINVAL;
  			}
  
  			/* check src1 operand */
  			err = check_reg_arg(env, insn->src_reg, SRC_OP);
  			if (err)
  				return err;
  			/* check src2 operand */
  			err = check_reg_arg(env, insn->dst_reg, SRC_OP);
  			if (err)
  				return err;
  
  			dst_reg_type = regs[insn->dst_reg].type;
  
  			/* check that memory (dst_reg + off) is writeable */
  			err = check_mem_access(env, env->insn_idx, insn->dst_reg,
  					       insn->off, BPF_SIZE(insn->code),
  					       BPF_WRITE, insn->src_reg, false);
  			if (err)
  				return err;
  
  			prev_dst_type = &env->insn_aux_data[env->insn_idx].ptr_type;
  
  			if (*prev_dst_type == NOT_INIT) {
  				*prev_dst_type = dst_reg_type;
  			} else if (reg_type_mismatch(dst_reg_type, *prev_dst_type)) {
  				verbose(env, "same insn cannot be used with different pointers\n");
  				return -EINVAL;
  			}
  
  		} else if (class == BPF_ST) {
  			if (BPF_MODE(insn->code) != BPF_MEM ||
  			    insn->src_reg != BPF_REG_0) {
  				verbose(env, "BPF_ST uses reserved fields\n");
  				return -EINVAL;
  			}
  			/* check src operand */
  			err = check_reg_arg(env, insn->dst_reg, SRC_OP);
  			if (err)
  				return err;
  
  			if (is_ctx_reg(env, insn->dst_reg)) {
  				verbose(env, "BPF_ST stores into R%d %s is not allowed\n",
  					insn->dst_reg,
  					reg_type_str(env, reg_state(env, insn->dst_reg)->type));
  				return -EACCES;
  			}
  
  			/* check that memory (dst_reg + off) is writeable */
  			err = check_mem_access(env, env->insn_idx, insn->dst_reg,
  					       insn->off, BPF_SIZE(insn->code),
  					       BPF_WRITE, -1, false);
  			if (err)
  				return err;
  
  		} else if (class == BPF_JMP || class == BPF_JMP32) {
  			u8 opcode = BPF_OP(insn->code);
  
  			env->jmps_processed++;
  			if (opcode == BPF_CALL) {
  				if (BPF_SRC(insn->code) != BPF_K ||
  				    (insn->src_reg != BPF_PSEUDO_KFUNC_CALL
  				     && insn->off != 0) ||
  				    (insn->src_reg != BPF_REG_0 &&
  				     insn->src_reg != BPF_PSEUDO_CALL &&
  				     insn->src_reg != BPF_PSEUDO_KFUNC_CALL) ||
  				    insn->dst_reg != BPF_REG_0 ||
  				    class == BPF_JMP32) {
  					verbose(env, "BPF_CALL uses reserved fields\n");
  					return -EINVAL;
  				}
  
  				if (env->cur_state->active_spin_lock &&
  				    (insn->src_reg == BPF_PSEUDO_CALL ||
  				     insn->imm != BPF_FUNC_spin_unlock)) {
  					verbose(env, "function calls are not allowed while holding a lock\n");
  					return -EINVAL;
  				}
  				if (insn->src_reg == BPF_PSEUDO_CALL)
  					err = check_func_call(env, insn, &env->insn_idx);
  				else if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL)
  					err = check_kfunc_call(env, insn, &env->insn_idx);
  				else
  					err = check_helper_call(env, insn, &env->insn_idx);
  				if (err)
  					return err;
  			} else if (opcode == BPF_JA) {
  				if (BPF_SRC(insn->code) != BPF_K ||
  				    insn->imm != 0 ||
  				    insn->src_reg != BPF_REG_0 ||
  				    insn->dst_reg != BPF_REG_0 ||
  				    class == BPF_JMP32) {
  					verbose(env, "BPF_JA uses reserved fields\n");
  					return -EINVAL;
  				}
  
  				env->insn_idx += insn->off + 1;
  				continue;
  
  			} else if (opcode == BPF_EXIT) {
  				if (BPF_SRC(insn->code) != BPF_K ||
  				    insn->imm != 0 ||
  				    insn->src_reg != BPF_REG_0 ||
  				    insn->dst_reg != BPF_REG_0 ||
  				    class == BPF_JMP32) {
  					verbose(env, "BPF_EXIT uses reserved fields\n");
  					return -EINVAL;
  				}
  
  				if (env->cur_state->active_spin_lock) {
  					verbose(env, "bpf_spin_unlock is missing\n");
  					return -EINVAL;
  				}
  
  				if (state->curframe) {
  					/* exit from nested function */
  					err = prepare_func_exit(env, &env->insn_idx);
  					if (err)
  						return err;
  					do_print_state = true;
  					continue;
  				}
  
  				err = check_reference_leak(env);
  				if (err)
  					return err;
  
  				err = check_return_code(env);
  				if (err)
  					return err;
  process_bpf_exit:
  				mark_verifier_state_scratched(env);
  				update_branch_counts(env, env->cur_state);
  				err = pop_stack(env, &prev_insn_idx,
  						&env->insn_idx, pop_log);
  				if (err < 0) {
  					if (err != -ENOENT)
  						return err;
  					break;
  				} else {
  					do_print_state = true;
  					continue;
  				}
  			} else {
  				err = check_cond_jmp_op(env, insn, &env->insn_idx);
  				if (err)
  					return err;
  			}
  		} else if (class == BPF_LD) {
  			u8 mode = BPF_MODE(insn->code);
  
  			if (mode == BPF_ABS || mode == BPF_IND) {
  				err = check_ld_abs(env, insn);
  				if (err)
  					return err;
  
  			} else if (mode == BPF_IMM) {
  				err = check_ld_imm(env, insn);
  				if (err)
  					return err;
  
  				env->insn_idx++;
  				sanitize_mark_insn_seen(env);
  			} else {
  				verbose(env, "invalid BPF_LD mode\n");
  				return -EINVAL;
  			}
  		} else {
  			verbose(env, "unknown insn class %d\n", class);
  			return -EINVAL;
  		}
  
  		env->insn_idx++;
  	}
  
  	return 0;
  }
  
  static int find_btf_percpu_datasec(struct btf *btf)
  {
  	const struct btf_type *t;
  	const char *tname;
  	int i, n;
  
  	/*
  	 * Both vmlinux and module each have their own ".data..percpu"
  	 * DATASECs in BTF. So for module's case, we need to skip vmlinux BTF
  	 * types to look at only module's own BTF types.
  	 */
  	n = btf_nr_types(btf);
  	if (btf_is_module(btf))
  		i = btf_nr_types(btf_vmlinux);
  	else
  		i = 1;
  
  	for(; i < n; i++) {
  		t = btf_type_by_id(btf, i);
  		if (BTF_INFO_KIND(t->info) != BTF_KIND_DATASEC)
  			continue;
  
  		tname = btf_name_by_offset(btf, t->name_off);
  		if (!strcmp(tname, ".data..percpu"))
  			return i;
  	}
  
  	return -ENOENT;
  }
  
  /* replace pseudo btf_id with kernel symbol address */
  static int check_pseudo_btf_id(struct bpf_verifier_env *env,
  			       struct bpf_insn *insn,
  			       struct bpf_insn_aux_data *aux)
  {
  	const struct btf_var_secinfo *vsi;
  	const struct btf_type *datasec;
  	struct btf_mod_pair *btf_mod;
  	const struct btf_type *t;
  	const char *sym_name;
  	bool percpu = false;
  	u32 type, id = insn->imm;
  	struct btf *btf;
  	s32 datasec_id;
  	u64 addr;
  	int i, btf_fd, err;
  
  	btf_fd = insn[1].imm;
  	if (btf_fd) {
  		btf = btf_get_by_fd(btf_fd);
  		if (IS_ERR(btf)) {
  			verbose(env, "invalid module BTF object FD specified.\n");
  			return -EINVAL;
  		}
  	} else {
  		if (!btf_vmlinux) {
  			verbose(env, "kernel is missing BTF, make sure CONFIG_DEBUG_INFO_BTF=y is specified in Kconfig.\n");
  			return -EINVAL;
  		}
  		btf = btf_vmlinux;
  		btf_get(btf);
  	}
  
  	t = btf_type_by_id(btf, id);
  	if (!t) {
  		verbose(env, "ldimm64 insn specifies invalid btf_id %d.\n", id);
  		err = -ENOENT;
  		goto err_put;
  	}
  
  	if (!btf_type_is_var(t)) {
  		verbose(env, "pseudo btf_id %d in ldimm64 isn't KIND_VAR.\n", id);
  		err = -EINVAL;
  		goto err_put;
  	}
  
  	sym_name = btf_name_by_offset(btf, t->name_off);
  	addr = kallsyms_lookup_name(sym_name);
  	if (!addr) {
  		verbose(env, "ldimm64 failed to find the address for kernel symbol '%s'.\n",
  			sym_name);
  		err = -ENOENT;
  		goto err_put;
  	}
  
  	datasec_id = find_btf_percpu_datasec(btf);
  	if (datasec_id > 0) {
  		datasec = btf_type_by_id(btf, datasec_id);
  		for_each_vsi(i, datasec, vsi) {
  			if (vsi->type == id) {
  				percpu = true;
  				break;
  			}
  		}
  	}
  
  	insn[0].imm = (u32)addr;
  	insn[1].imm = addr >> 32;
  
  	type = t->type;
  	t = btf_type_skip_modifiers(btf, type, NULL);
  	if (percpu) {
  		aux->btf_var.reg_type = PTR_TO_BTF_ID | MEM_PERCPU;
  		aux->btf_var.btf = btf;
  		aux->btf_var.btf_id = type;
  	} else if (!btf_type_is_struct(t)) {
  		const struct btf_type *ret;
  		const char *tname;
  		u32 tsize;
  
  		/* resolve the type size of ksym. */
  		ret = btf_resolve_size(btf, t, &tsize);
  		if (IS_ERR(ret)) {
  			tname = btf_name_by_offset(btf, t->name_off);
  			verbose(env, "ldimm64 unable to resolve the size of type '%s': %ld\n",
  				tname, PTR_ERR(ret));
  			err = -EINVAL;
  			goto err_put;
  		}
  		aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY;
  		aux->btf_var.mem_size = tsize;
  	} else {
  		aux->btf_var.reg_type = PTR_TO_BTF_ID;
  		aux->btf_var.btf = btf;
  		aux->btf_var.btf_id = type;
  	}
  
  	/* check whether we recorded this BTF (and maybe module) already */
  	for (i = 0; i < env->used_btf_cnt; i++) {
  		if (env->used_btfs[i].btf == btf) {
  			btf_put(btf);
  			return 0;
  		}
  	}
  
  	if (env->used_btf_cnt >= MAX_USED_BTFS) {
  		err = -E2BIG;
  		goto err_put;
  	}
  
  	btf_mod = &env->used_btfs[env->used_btf_cnt];
  	btf_mod->btf = btf;
  	btf_mod->module = NULL;
  
  	/* if we reference variables from kernel module, bump its refcount */
  	if (btf_is_module(btf)) {
  		btf_mod->module = btf_try_get_module(btf);
  		if (!btf_mod->module) {
  			err = -ENXIO;
  			goto err_put;
  		}
  	}
  
  	env->used_btf_cnt++;
  
  	return 0;
  err_put:
  	btf_put(btf);
  	return err;
  }
  
  static int check_map_prealloc(struct bpf_map *map)
  {
  	return (map->map_type != BPF_MAP_TYPE_HASH &&
  		map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
  		map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) ||
  		!(map->map_flags & BPF_F_NO_PREALLOC);
  }
  
  static bool is_tracing_prog_type(enum bpf_prog_type type)
  {
  	switch (type) {
  	case BPF_PROG_TYPE_KPROBE:
  	case BPF_PROG_TYPE_TRACEPOINT:
  	case BPF_PROG_TYPE_PERF_EVENT:
  	case BPF_PROG_TYPE_RAW_TRACEPOINT:
  		return true;
  	default:
  		return false;
  	}
  }
  
  static bool is_preallocated_map(struct bpf_map *map)
  {
  	if (!check_map_prealloc(map))
  		return false;
  	if (map->inner_map_meta && !check_map_prealloc(map->inner_map_meta))
  		return false;
  	return true;
  }
  
  static int check_map_prog_compatibility(struct bpf_verifier_env *env,
  					struct bpf_map *map,
  					struct bpf_prog *prog)
  
  {
  	enum bpf_prog_type prog_type = resolve_prog_type(prog);
  	/*
  	 * Validate that trace type programs use preallocated hash maps.
  	 *
  	 * For programs attached to PERF events this is mandatory as the
  	 * perf NMI can hit any arbitrary code sequence.
  	 *
  	 * All other trace types using preallocated hash maps are unsafe as
  	 * well because tracepoint or kprobes can be inside locked regions
  	 * of the memory allocator or at a place where a recursion into the
  	 * memory allocator would see inconsistent state.
  	 *
  	 * On RT enabled kernels run-time allocation of all trace type
  	 * programs is strictly prohibited due to lock type constraints. On
  	 * !RT kernels it is allowed for backwards compatibility reasons for
  	 * now, but warnings are emitted so developers are made aware of
  	 * the unsafety and can fix their programs before this is enforced.
  	 */
  	if (is_tracing_prog_type(prog_type) && !is_preallocated_map(map)) {
  		if (prog_type == BPF_PROG_TYPE_PERF_EVENT) {
  			verbose(env, "perf_event programs can only use preallocated hash map\n");
  			return -EINVAL;
  		}
  		if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
  			verbose(env, "trace type programs can only use preallocated hash map\n");
  			return -EINVAL;
  		}
  		WARN_ONCE(1, "trace type BPF program uses run-time allocation\n");
  		verbose(env, "trace type programs with run-time allocated hash maps are unsafe. Switch to preallocated hash maps.\n");
  	}
  
  	if (map_value_has_spin_lock(map)) {
  		if (prog_type == BPF_PROG_TYPE_SOCKET_FILTER) {
  			verbose(env, "socket filter progs cannot use bpf_spin_lock yet\n");
  			return -EINVAL;
  		}
  
  		if (is_tracing_prog_type(prog_type)) {
  			verbose(env, "tracing progs cannot use bpf_spin_lock yet\n");
  			return -EINVAL;
  		}
  
  		if (prog->aux->sleepable) {
  			verbose(env, "sleepable progs cannot use bpf_spin_lock yet\n");
  			return -EINVAL;
  		}
  	}
  
  	if (map_value_has_timer(map)) {
  		if (is_tracing_prog_type(prog_type)) {
  			verbose(env, "tracing progs cannot use bpf_timer yet\n");
  			return -EINVAL;
  		}
  	}
  
  	if ((bpf_prog_is_dev_bound(prog->aux) || bpf_map_is_dev_bound(map)) &&
  	    !bpf_offload_prog_map_match(prog, map)) {
  		verbose(env, "offload device mismatch between prog and map\n");
  		return -EINVAL;
  	}
  
  	if (map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
  		verbose(env, "bpf_struct_ops map cannot be used in prog\n");
  		return -EINVAL;
  	}
  
  	if (prog->aux->sleepable)
  		switch (map->map_type) {
  		case BPF_MAP_TYPE_HASH:
  		case BPF_MAP_TYPE_LRU_HASH:
  		case BPF_MAP_TYPE_ARRAY:
  		case BPF_MAP_TYPE_PERCPU_HASH:
  		case BPF_MAP_TYPE_PERCPU_ARRAY:
  		case BPF_MAP_TYPE_LRU_PERCPU_HASH:
  		case BPF_MAP_TYPE_ARRAY_OF_MAPS:
  		case BPF_MAP_TYPE_HASH_OF_MAPS:
  			if (!is_preallocated_map(map)) {
  				verbose(env,
  					"Sleepable programs can only use preallocated maps\n");
  				return -EINVAL;
  			}
  			break;
  		case BPF_MAP_TYPE_RINGBUF:
  		case BPF_MAP_TYPE_INODE_STORAGE:
  		case BPF_MAP_TYPE_SK_STORAGE:
  		case BPF_MAP_TYPE_TASK_STORAGE:
  			break;
  		default:
  			verbose(env,
  				"Sleepable programs can only use array, hash, and ringbuf maps\n");
  			return -EINVAL;
  		}
  
  	return 0;
  }
  
  static bool bpf_map_is_cgroup_storage(struct bpf_map *map)
  {
  	return (map->map_type == BPF_MAP_TYPE_CGROUP_STORAGE ||
  		map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE);
  }
  
  /* find and rewrite pseudo imm in ld_imm64 instructions:
   *
   * 1. if it accesses map FD, replace it with actual map pointer.
   * 2. if it accesses btf_id of a VAR, replace it with pointer to the var.
   *
   * NOTE: btf_vmlinux is required for converting pseudo btf_id.
   */
  static int resolve_pseudo_ldimm64(struct bpf_verifier_env *env)
  {
  	struct bpf_insn *insn = env->prog->insnsi;
  	int insn_cnt = env->prog->len;
  	int i, j, err;
  
  	err = bpf_prog_calc_tag(env->prog);
  	if (err)
  		return err;
  
  	for (i = 0; i < insn_cnt; i++, insn++) {
  		if (BPF_CLASS(insn->code) == BPF_LDX &&
  		    (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) {
  			verbose(env, "BPF_LDX uses reserved fields\n");
  			return -EINVAL;
  		}
  
  		if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
  			struct bpf_insn_aux_data *aux;
  			struct bpf_map *map;
  			struct fd f;
  			u64 addr;
  			u32 fd;
  
  			if (i == insn_cnt - 1 || insn[1].code != 0 ||
  			    insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
  			    insn[1].off != 0) {
  				verbose(env, "invalid bpf_ld_imm64 insn\n");
  				return -EINVAL;
  			}
  
  			if (insn[0].src_reg == 0)
  				/* valid generic load 64-bit imm */
  				goto next_insn;
  
  			if (insn[0].src_reg == BPF_PSEUDO_BTF_ID) {
  				aux = &env->insn_aux_data[i];
  				err = check_pseudo_btf_id(env, insn, aux);
  				if (err)
  					return err;
  				goto next_insn;
  			}
  
  			if (insn[0].src_reg == BPF_PSEUDO_FUNC) {
  				aux = &env->insn_aux_data[i];
  				aux->ptr_type = PTR_TO_FUNC;
  				goto next_insn;
  			}
  
  			/* In final convert_pseudo_ld_imm64() step, this is
  			 * converted into regular 64-bit imm load insn.
  			 */
  			switch (insn[0].src_reg) {
  			case BPF_PSEUDO_MAP_VALUE:
  			case BPF_PSEUDO_MAP_IDX_VALUE:
  				break;
  			case BPF_PSEUDO_MAP_FD:
  			case BPF_PSEUDO_MAP_IDX:
  				if (insn[1].imm == 0)
  					break;
  				fallthrough;
  			default:
  				verbose(env, "unrecognized bpf_ld_imm64 insn\n");
  				return -EINVAL;
  			}
  
  			switch (insn[0].src_reg) {
  			case BPF_PSEUDO_MAP_IDX_VALUE:
  			case BPF_PSEUDO_MAP_IDX:
  				if (bpfptr_is_null(env->fd_array)) {
  					verbose(env, "fd_idx without fd_array is invalid\n");
  					return -EPROTO;
  				}
  				if (copy_from_bpfptr_offset(&fd, env->fd_array,
  							    insn[0].imm * sizeof(fd),
  							    sizeof(fd)))
  					return -EFAULT;
  				break;
  			default:
  				fd = insn[0].imm;
  				break;
  			}
  
  			f = fdget(fd);
  			map = __bpf_map_get(f);
  			if (IS_ERR(map)) {
  				verbose(env, "fd %d is not pointing to valid bpf_map\n",
  					insn[0].imm);
  				return PTR_ERR(map);
  			}
  
  			err = check_map_prog_compatibility(env, map, env->prog);
  			if (err) {
  				fdput(f);
  				return err;
  			}
  
  			aux = &env->insn_aux_data[i];
  			if (insn[0].src_reg == BPF_PSEUDO_MAP_FD ||
  			    insn[0].src_reg == BPF_PSEUDO_MAP_IDX) {
  				addr = (unsigned long)map;
  			} else {
  				u32 off = insn[1].imm;
  
  				if (off >= BPF_MAX_VAR_OFF) {
  					verbose(env, "direct value offset of %u is not allowed\n", off);
  					fdput(f);
  					return -EINVAL;
  				}
  
  				if (!map->ops->map_direct_value_addr) {
  					verbose(env, "no direct value access support for this map type\n");
  					fdput(f);
  					return -EINVAL;
  				}
  
  				err = map->ops->map_direct_value_addr(map, &addr, off);
  				if (err) {
  					verbose(env, "invalid access to map value pointer, value_size=%u off=%u\n",
  						map->value_size, off);
  					fdput(f);
  					return err;
  				}
  
  				aux->map_off = off;
  				addr += off;
  			}
  
  			insn[0].imm = (u32)addr;
  			insn[1].imm = addr >> 32;
  
  			/* check whether we recorded this map already */
  			for (j = 0; j < env->used_map_cnt; j++) {
  				if (env->used_maps[j] == map) {
  					aux->map_index = j;
  					fdput(f);
  					goto next_insn;
  				}
  			}
  
  			if (env->used_map_cnt >= MAX_USED_MAPS) {
  				fdput(f);
  				return -E2BIG;
  			}
  
  			/* hold the map. If the program is rejected by verifier,
  			 * the map will be released by release_maps() or it
  			 * will be used by the valid program until it's unloaded
  			 * and all maps are released in free_used_maps()
  			 */
  			bpf_map_inc(map);
  
  			aux->map_index = env->used_map_cnt;
  			env->used_maps[env->used_map_cnt++] = map;
  
  			if (bpf_map_is_cgroup_storage(map) &&
  			    bpf_cgroup_storage_assign(env->prog->aux, map)) {
  				verbose(env, "only one cgroup storage of each type is allowed\n");
  				fdput(f);
  				return -EBUSY;
  			}
  
  			fdput(f);
  next_insn:
  			insn++;
  			i++;
  			continue;
  		}
  
  		/* Basic sanity check before we invest more work here. */
  		if (!bpf_opcode_in_insntable(insn->code)) {
  			verbose(env, "unknown opcode %02x\n", insn->code);
  			return -EINVAL;
  		}
  	}
  
  	/* now all pseudo BPF_LD_IMM64 instructions load valid
  	 * 'struct bpf_map *' into a register instead of user map_fd.
  	 * These pointers will be used later by verifier to validate map access.
  	 */
  	return 0;
  }
  
  /* drop refcnt of maps used by the rejected program */
  static void release_maps(struct bpf_verifier_env *env)
  {
  	__bpf_free_used_maps(env->prog->aux, env->used_maps,
  			     env->used_map_cnt);
  }
  
  /* drop refcnt of maps used by the rejected program */
  static void release_btfs(struct bpf_verifier_env *env)
  {
  	__bpf_free_used_btfs(env->prog->aux, env->used_btfs,
  			     env->used_btf_cnt);
  }
  
  /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
  static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
  {
  	struct bpf_insn *insn = env->prog->insnsi;
  	int insn_cnt = env->prog->len;
  	int i;
  
  	for (i = 0; i < insn_cnt; i++, insn++) {
  		if (insn->code != (BPF_LD | BPF_IMM | BPF_DW))
  			continue;
  		if (insn->src_reg == BPF_PSEUDO_FUNC)
  			continue;
  		insn->src_reg = 0;
  	}
  }
  
  /* single env->prog->insni[off] instruction was replaced with the range
   * insni[off, off + cnt).  Adjust corresponding insn_aux_data by copying
   * [0, off) and [off, end) to new locations, so the patched range stays zero
   */
  static void adjust_insn_aux_data(struct bpf_verifier_env *env,
  				 struct bpf_insn_aux_data *new_data,
  				 struct bpf_prog *new_prog, u32 off, u32 cnt)
  {
  	struct bpf_insn_aux_data *old_data = env->insn_aux_data;
  	struct bpf_insn *insn = new_prog->insnsi;
  	u32 old_seen = old_data[off].seen;
  	u32 prog_len;
  	int i;
  
  	/* aux info at OFF always needs adjustment, no matter fast path
  	 * (cnt == 1) is taken or not. There is no guarantee INSN at OFF is the
  	 * original insn at old prog.
  	 */
  	old_data[off].zext_dst = insn_has_def32(env, insn + off + cnt - 1);
  
  	if (cnt == 1)
  		return;
  	prog_len = new_prog->len;
  
  	memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off);
  	memcpy(new_data + off + cnt - 1, old_data + off,
  	       sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
  	for (i = off; i < off + cnt - 1; i++) {
  		/* Expand insni[off]'s seen count to the patched range. */
  		new_data[i].seen = old_seen;
  		new_data[i].zext_dst = insn_has_def32(env, insn + i);
  	}
  	env->insn_aux_data = new_data;
  	vfree(old_data);
  }
  
  static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len)
  {
  	int i;
  
  	if (len == 1)
  		return;
  	/* NOTE: fake 'exit' subprog should be updated as well. */
  	for (i = 0; i <= env->subprog_cnt; i++) {
  		if (env->subprog_info[i].start <= off)
  			continue;
  		env->subprog_info[i].start += len - 1;
  	}
  }
  
  static void adjust_poke_descs(struct bpf_prog *prog, u32 off, u32 len)
  {
  	struct bpf_jit_poke_descriptor *tab = prog->aux->poke_tab;
  	int i, sz = prog->aux->size_poke_tab;
  	struct bpf_jit_poke_descriptor *desc;
  
  	for (i = 0; i < sz; i++) {
  		desc = &tab[i];
  		if (desc->insn_idx <= off)
  			continue;
  		desc->insn_idx += len - 1;
  	}
  }
  
  static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off,
  					    const struct bpf_insn *patch, u32 len)
  {
  	struct bpf_prog *new_prog;
  	struct bpf_insn_aux_data *new_data = NULL;
  
  	if (len > 1) {
  		new_data = vzalloc(array_size(env->prog->len + len - 1,
  					      sizeof(struct bpf_insn_aux_data)));
  		if (!new_data)
  			return NULL;
  	}
  
  	new_prog = bpf_patch_insn_single(env->prog, off, patch, len);
  	if (IS_ERR(new_prog)) {
  		if (PTR_ERR(new_prog) == -ERANGE)
  			verbose(env,
  				"insn %d cannot be patched due to 16-bit range\n",
  				env->insn_aux_data[off].orig_idx);
  		vfree(new_data);
  		return NULL;
  	}
  	adjust_insn_aux_data(env, new_data, new_prog, off, len);
  	adjust_subprog_starts(env, off, len);
  	adjust_poke_descs(new_prog, off, len);
  	return new_prog;
  }
  
  static int adjust_subprog_starts_after_remove(struct bpf_verifier_env *env,
  					      u32 off, u32 cnt)
  {
  	int i, j;
  
  	/* find first prog starting at or after off (first to remove) */
  	for (i = 0; i < env->subprog_cnt; i++)
  		if (env->subprog_info[i].start >= off)
  			break;
  	/* find first prog starting at or after off + cnt (first to stay) */
  	for (j = i; j < env->subprog_cnt; j++)
  		if (env->subprog_info[j].start >= off + cnt)
  			break;
  	/* if j doesn't start exactly at off + cnt, we are just removing
  	 * the front of previous prog
  	 */
  	if (env->subprog_info[j].start != off + cnt)
  		j--;
  
  	if (j > i) {
  		struct bpf_prog_aux *aux = env->prog->aux;
  		int move;
  
  		/* move fake 'exit' subprog as well */
  		move = env->subprog_cnt + 1 - j;
  
  		memmove(env->subprog_info + i,
  			env->subprog_info + j,
  			sizeof(*env->subprog_info) * move);
  		env->subprog_cnt -= j - i;
  
  		/* remove func_info */
  		if (aux->func_info) {
  			move = aux->func_info_cnt - j;
  
  			memmove(aux->func_info + i,
  				aux->func_info + j,
  				sizeof(*aux->func_info) * move);
  			aux->func_info_cnt -= j - i;
  			/* func_info->insn_off is set after all code rewrites,
  			 * in adjust_btf_func() - no need to adjust
  			 */
  		}
  	} else {
  		/* convert i from "first prog to remove" to "first to adjust" */
  		if (env->subprog_info[i].start == off)
  			i++;
  	}
  
  	/* update fake 'exit' subprog as well */
  	for (; i <= env->subprog_cnt; i++)
  		env->subprog_info[i].start -= cnt;
  
  	return 0;
  }
  
  static int bpf_adj_linfo_after_remove(struct bpf_verifier_env *env, u32 off,
  				      u32 cnt)
  {
  	struct bpf_prog *prog = env->prog;
  	u32 i, l_off, l_cnt, nr_linfo;
  	struct bpf_line_info *linfo;
  
  	nr_linfo = prog->aux->nr_linfo;
  	if (!nr_linfo)
  		return 0;
  
  	linfo = prog->aux->linfo;
  
  	/* find first line info to remove, count lines to be removed */
  	for (i = 0; i < nr_linfo; i++)
  		if (linfo[i].insn_off >= off)
  			break;
  
  	l_off = i;
  	l_cnt = 0;
  	for (; i < nr_linfo; i++)
  		if (linfo[i].insn_off < off + cnt)
  			l_cnt++;
  		else
  			break;
  
  	/* First live insn doesn't match first live linfo, it needs to "inherit"
  	 * last removed linfo.  prog is already modified, so prog->len == off
  	 * means no live instructions after (tail of the program was removed).
  	 */
  	if (prog->len != off && l_cnt &&
  	    (i == nr_linfo || linfo[i].insn_off != off + cnt)) {
  		l_cnt--;
  		linfo[--i].insn_off = off + cnt;
  	}
  
  	/* remove the line info which refer to the removed instructions */
  	if (l_cnt) {
  		memmove(linfo + l_off, linfo + i,
  			sizeof(*linfo) * (nr_linfo - i));
  
  		prog->aux->nr_linfo -= l_cnt;
  		nr_linfo = prog->aux->nr_linfo;
  	}
  
  	/* pull all linfo[i].insn_off >= off + cnt in by cnt */
  	for (i = l_off; i < nr_linfo; i++)
  		linfo[i].insn_off -= cnt;
  
  	/* fix up all subprogs (incl. 'exit') which start >= off */
  	for (i = 0; i <= env->subprog_cnt; i++)
  		if (env->subprog_info[i].linfo_idx > l_off) {
  			/* program may have started in the removed region but
  			 * may not be fully removed
  			 */
  			if (env->subprog_info[i].linfo_idx >= l_off + l_cnt)
  				env->subprog_info[i].linfo_idx -= l_cnt;
  			else
  				env->subprog_info[i].linfo_idx = l_off;
  		}
  
  	return 0;
  }
  
  static int verifier_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt)
  {
  	struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
  	unsigned int orig_prog_len = env->prog->len;
  	int err;
  
  	if (bpf_prog_is_dev_bound(env->prog->aux))
  		bpf_prog_offload_remove_insns(env, off, cnt);
  
  	err = bpf_remove_insns(env->prog, off, cnt);
  	if (err)
  		return err;
  
  	err = adjust_subprog_starts_after_remove(env, off, cnt);
  	if (err)
  		return err;
  
  	err = bpf_adj_linfo_after_remove(env, off, cnt);
  	if (err)
  		return err;
  
  	memmove(aux_data + off,	aux_data + off + cnt,
  		sizeof(*aux_data) * (orig_prog_len - off - cnt));
  
  	return 0;
  }
  
  /* The verifier does more data flow analysis than llvm and will not
   * explore branches that are dead at run time. Malicious programs can
   * have dead code too. Therefore replace all dead at-run-time code
   * with 'ja -1'.
   *
   * Just nops are not optimal, e.g. if they would sit at the end of the
   * program and through another bug we would manage to jump there, then
   * we'd execute beyond program memory otherwise. Returning exception
   * code also wouldn't work since we can have subprogs where the dead
   * code could be located.
   */
  static void sanitize_dead_code(struct bpf_verifier_env *env)
  {
  	struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
  	struct bpf_insn trap = BPF_JMP_IMM(BPF_JA, 0, 0, -1);
  	struct bpf_insn *insn = env->prog->insnsi;
  	const int insn_cnt = env->prog->len;
  	int i;
  
  	for (i = 0; i < insn_cnt; i++) {
  		if (aux_data[i].seen)
  			continue;
  		memcpy(insn + i, &trap, sizeof(trap));
  		aux_data[i].zext_dst = false;
  	}
  }
  
  static bool insn_is_cond_jump(u8 code)
  {
  	u8 op;
  
  	if (BPF_CLASS(code) == BPF_JMP32)
  		return true;
  
  	if (BPF_CLASS(code) != BPF_JMP)
  		return false;
  
  	op = BPF_OP(code);
  	return op != BPF_JA && op != BPF_EXIT && op != BPF_CALL;
  }
  
  static void opt_hard_wire_dead_code_branches(struct bpf_verifier_env *env)
  {
  	struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
  	struct bpf_insn ja = BPF_JMP_IMM(BPF_JA, 0, 0, 0);
  	struct bpf_insn *insn = env->prog->insnsi;
  	const int insn_cnt = env->prog->len;
  	int i;
  
  	for (i = 0; i < insn_cnt; i++, insn++) {
  		if (!insn_is_cond_jump(insn->code))
  			continue;
  
  		if (!aux_data[i + 1].seen)
  			ja.off = insn->off;
  		else if (!aux_data[i + 1 + insn->off].seen)
  			ja.off = 0;
  		else
  			continue;
  
  		if (bpf_prog_is_dev_bound(env->prog->aux))
  			bpf_prog_offload_replace_insn(env, i, &ja);
  
  		memcpy(insn, &ja, sizeof(ja));
  	}
  }
  
  static int opt_remove_dead_code(struct bpf_verifier_env *env)
  {
  	struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
  	int insn_cnt = env->prog->len;
  	int i, err;
  
  	for (i = 0; i < insn_cnt; i++) {
  		int j;
  
  		j = 0;
  		while (i + j < insn_cnt && !aux_data[i + j].seen)
  			j++;
  		if (!j)
  			continue;
  
  		err = verifier_remove_insns(env, i, j);
  		if (err)
  			return err;
  		insn_cnt = env->prog->len;
  	}
  
  	return 0;
  }
  
  static int opt_remove_nops(struct bpf_verifier_env *env)
  {
  	const struct bpf_insn ja = BPF_JMP_IMM(BPF_JA, 0, 0, 0);
  	struct bpf_insn *insn = env->prog->insnsi;
  	int insn_cnt = env->prog->len;
  	int i, err;
  
  	for (i = 0; i < insn_cnt; i++) {
  		if (memcmp(&insn[i], &ja, sizeof(ja)))
  			continue;
  
  		err = verifier_remove_insns(env, i, 1);
  		if (err)
  			return err;
  		insn_cnt--;
  		i--;
  	}
  
  	return 0;
  }
  
  static int opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env,
  					 const union bpf_attr *attr)
  {
  	struct bpf_insn *patch, zext_patch[2], rnd_hi32_patch[4];
  	struct bpf_insn_aux_data *aux = env->insn_aux_data;
  	int i, patch_len, delta = 0, len = env->prog->len;
  	struct bpf_insn *insns = env->prog->insnsi;
  	struct bpf_prog *new_prog;
  	bool rnd_hi32;
  
  	rnd_hi32 = attr->prog_flags & BPF_F_TEST_RND_HI32;
  	zext_patch[1] = BPF_ZEXT_REG(0);
  	rnd_hi32_patch[1] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, 0);
  	rnd_hi32_patch[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_AX, 32);
  	rnd_hi32_patch[3] = BPF_ALU64_REG(BPF_OR, 0, BPF_REG_AX);
  	for (i = 0; i < len; i++) {
  		int adj_idx = i + delta;
  		struct bpf_insn insn;
  		int load_reg;
  
  		insn = insns[adj_idx];
  		load_reg = insn_def_regno(&insn);
  		if (!aux[adj_idx].zext_dst) {
  			u8 code, class;
  			u32 imm_rnd;
  
  			if (!rnd_hi32)
  				continue;
  
  			code = insn.code;
  			class = BPF_CLASS(code);
  			if (load_reg == -1)
  				continue;
  
  			/* NOTE: arg "reg" (the fourth one) is only used for
  			 *       BPF_STX + SRC_OP, so it is safe to pass NULL
  			 *       here.
  			 */
  			if (is_reg64(env, &insn, load_reg, NULL, DST_OP)) {
  				if (class == BPF_LD &&
  				    BPF_MODE(code) == BPF_IMM)
  					i++;
  				continue;
  			}
  
  			/* ctx load could be transformed into wider load. */
  			if (class == BPF_LDX &&
  			    aux[adj_idx].ptr_type == PTR_TO_CTX)
  				continue;
  
  			imm_rnd = get_random_int();
  			rnd_hi32_patch[0] = insn;
  			rnd_hi32_patch[1].imm = imm_rnd;
  			rnd_hi32_patch[3].dst_reg = load_reg;
  			patch = rnd_hi32_patch;
  			patch_len = 4;
  			goto apply_patch_buffer;
  		}
  
  		/* Add in an zero-extend instruction if a) the JIT has requested
  		 * it or b) it's a CMPXCHG.
  		 *
  		 * The latter is because: BPF_CMPXCHG always loads a value into
  		 * R0, therefore always zero-extends. However some archs'
  		 * equivalent instruction only does this load when the
  		 * comparison is successful. This detail of CMPXCHG is
  		 * orthogonal to the general zero-extension behaviour of the
  		 * CPU, so it's treated independently of bpf_jit_needs_zext.
  		 */
  		if (!bpf_jit_needs_zext() && !is_cmpxchg_insn(&insn))
  			continue;
  
  		if (WARN_ON(load_reg == -1)) {
  			verbose(env, "verifier bug. zext_dst is set, but no reg is defined\n");
  			return -EFAULT;
  		}
  
  		zext_patch[0] = insn;
  		zext_patch[1].dst_reg = load_reg;
  		zext_patch[1].src_reg = load_reg;
  		patch = zext_patch;
  		patch_len = 2;
  apply_patch_buffer:
  		new_prog = bpf_patch_insn_data(env, adj_idx, patch, patch_len);
  		if (!new_prog)
  			return -ENOMEM;
  		env->prog = new_prog;
  		insns = new_prog->insnsi;
  		aux = env->insn_aux_data;
  		delta += patch_len - 1;
  	}
  
  	return 0;
  }
  
  /* convert load instructions that access fields of a context type into a
   * sequence of instructions that access fields of the underlying structure:
   *     struct __sk_buff    -> struct sk_buff
   *     struct bpf_sock_ops -> struct sock
   */
  static int convert_ctx_accesses(struct bpf_verifier_env *env)
  {
  	const struct bpf_verifier_ops *ops = env->ops;
  	int i, cnt, size, ctx_field_size, delta = 0;
  	const int insn_cnt = env->prog->len;
  	struct bpf_insn insn_buf[16], *insn;
  	u32 target_size, size_default, off;
  	struct bpf_prog *new_prog;
  	enum bpf_access_type type;
  	bool is_narrower_load;
  
  	if (ops->gen_prologue || env->seen_direct_write) {
  		if (!ops->gen_prologue) {
  			verbose(env, "bpf verifier is misconfigured\n");
  			return -EINVAL;
  		}
  		cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
  					env->prog);
  		if (cnt >= ARRAY_SIZE(insn_buf)) {
  			verbose(env, "bpf verifier is misconfigured\n");
  			return -EINVAL;
  		} else if (cnt) {
  			new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
  			if (!new_prog)
  				return -ENOMEM;
  
  			env->prog = new_prog;
  			delta += cnt - 1;
  		}
  	}
  
  	if (bpf_prog_is_dev_bound(env->prog->aux))
  		return 0;
  
  	insn = env->prog->insnsi + delta;
  
  	for (i = 0; i < insn_cnt; i++, insn++) {
  		bpf_convert_ctx_access_t convert_ctx_access;
  		bool ctx_access;
  
  		if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) ||
  		    insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
  		    insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
  		    insn->code == (BPF_LDX | BPF_MEM | BPF_DW)) {
  			type = BPF_READ;
  			ctx_access = true;
  		} else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) ||
  			   insn->code == (BPF_STX | BPF_MEM | BPF_H) ||
  			   insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
  			   insn->code == (BPF_STX | BPF_MEM | BPF_DW) ||
  			   insn->code == (BPF_ST | BPF_MEM | BPF_B) ||
  			   insn->code == (BPF_ST | BPF_MEM | BPF_H) ||
  			   insn->code == (BPF_ST | BPF_MEM | BPF_W) ||
  			   insn->code == (BPF_ST | BPF_MEM | BPF_DW)) {
  			type = BPF_WRITE;
  			ctx_access = BPF_CLASS(insn->code) == BPF_STX;
  		} else {
  			continue;
  		}
  
  		if (type == BPF_WRITE &&
  		    env->insn_aux_data[i + delta].sanitize_stack_spill) {
  			struct bpf_insn patch[] = {
  				*insn,
  				BPF_ST_NOSPEC(),
  			};
  
  			cnt = ARRAY_SIZE(patch);
  			new_prog = bpf_patch_insn_data(env, i + delta, patch, cnt);
  			if (!new_prog)
  				return -ENOMEM;
  
  			delta    += cnt - 1;
  			env->prog = new_prog;
  			insn      = new_prog->insnsi + i + delta;
  			continue;
  		}
  
  		if (!ctx_access)
  			continue;
  
  		switch (env->insn_aux_data[i + delta].ptr_type) {
  		case PTR_TO_CTX:
  			if (!ops->convert_ctx_access)
  				continue;
  			convert_ctx_access = ops->convert_ctx_access;
  			break;
  		case PTR_TO_SOCKET:
  		case PTR_TO_SOCK_COMMON:
  			convert_ctx_access = bpf_sock_convert_ctx_access;
  			break;
  		case PTR_TO_TCP_SOCK:
  			convert_ctx_access = bpf_tcp_sock_convert_ctx_access;
  			break;
  		case PTR_TO_XDP_SOCK:
  			convert_ctx_access = bpf_xdp_sock_convert_ctx_access;
  			break;
  		case PTR_TO_BTF_ID:
  			if (type == BPF_READ) {
  				insn->code = BPF_LDX | BPF_PROBE_MEM |
  					BPF_SIZE((insn)->code);
  				env->prog->aux->num_exentries++;
  			} else if (resolve_prog_type(env->prog) != BPF_PROG_TYPE_STRUCT_OPS) {
  				verbose(env, "Writes through BTF pointers are not allowed\n");
  				return -EINVAL;
  			}
  			continue;
  		default:
  			continue;
  		}
  
  		ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size;
  		size = BPF_LDST_BYTES(insn);
  
  		/* If the read access is a narrower load of the field,
  		 * convert to a 4/8-byte load, to minimum program type specific
  		 * convert_ctx_access changes. If conversion is successful,
  		 * we will apply proper mask to the result.
  		 */
  		is_narrower_load = size < ctx_field_size;
  		size_default = bpf_ctx_off_adjust_machine(ctx_field_size);
  		off = insn->off;
  		if (is_narrower_load) {
  			u8 size_code;
  
  			if (type == BPF_WRITE) {
  				verbose(env, "bpf verifier narrow ctx access misconfigured\n");
  				return -EINVAL;
  			}
  
  			size_code = BPF_H;
  			if (ctx_field_size == 4)
  				size_code = BPF_W;
  			else if (ctx_field_size == 8)
  				size_code = BPF_DW;
  
  			insn->off = off & ~(size_default - 1);
  			insn->code = BPF_LDX | BPF_MEM | size_code;
  		}
  
  		target_size = 0;
  		cnt = convert_ctx_access(type, insn, insn_buf, env->prog,
  					 &target_size);
  		if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) ||
  		    (ctx_field_size && !target_size)) {
  			verbose(env, "bpf verifier is misconfigured\n");
  			return -EINVAL;
  		}
  
  		if (is_narrower_load && size < target_size) {
  			u8 shift = bpf_ctx_narrow_access_offset(
  				off, size, size_default) * 8;
  			if (shift && cnt + 1 >= ARRAY_SIZE(insn_buf)) {
  				verbose(env, "bpf verifier narrow ctx load misconfigured\n");
  				return -EINVAL;
  			}
  			if (ctx_field_size <= 4) {
  				if (shift)
  					insn_buf[cnt++] = BPF_ALU32_IMM(BPF_RSH,
  									insn->dst_reg,
  									shift);
  				insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg,
  								(1 << size * 8) - 1);
  			} else {
  				if (shift)
  					insn_buf[cnt++] = BPF_ALU64_IMM(BPF_RSH,
  									insn->dst_reg,
  									shift);
  				insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg,
  								(1ULL << size * 8) - 1);
  			}
  		}
  
  		new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
  		if (!new_prog)
  			return -ENOMEM;
  
  		delta += cnt - 1;
  
  		/* keep walking new program and skip insns we just inserted */
  		env->prog = new_prog;
  		insn      = new_prog->insnsi + i + delta;
  	}
  
  	return 0;
  }
  
  static int jit_subprogs(struct bpf_verifier_env *env)
  {
  	struct bpf_prog *prog = env->prog, **func, *tmp;
  	int i, j, subprog_start, subprog_end = 0, len, subprog;
  	struct bpf_map *map_ptr;
  	struct bpf_insn *insn;
  	void *old_bpf_func;
  	int err, num_exentries;
  
  	if (env->subprog_cnt <= 1)
  		return 0;
  
  	for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
  		if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn))
  			continue;
  
  		/* Upon error here we cannot fall back to interpreter but
  		 * need a hard reject of the program. Thus -EFAULT is
  		 * propagated in any case.
  		 */
  		subprog = find_subprog(env, i + insn->imm + 1);
  		if (subprog < 0) {
  			WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
  				  i + insn->imm + 1);
  			return -EFAULT;
  		}
  		/* temporarily remember subprog id inside insn instead of
  		 * aux_data, since next loop will split up all insns into funcs
  		 */
  		insn->off = subprog;
  		/* remember original imm in case JIT fails and fallback
  		 * to interpreter will be needed
  		 */
  		env->insn_aux_data[i].call_imm = insn->imm;
  		/* point imm to __bpf_call_base+1 from JITs point of view */
  		insn->imm = 1;
  		if (bpf_pseudo_func(insn))
  			/* jit (e.g. x86_64) may emit fewer instructions
  			 * if it learns a u32 imm is the same as a u64 imm.
  			 * Force a non zero here.
  			 */
  			insn[1].imm = 1;
  	}
  
  	err = bpf_prog_alloc_jited_linfo(prog);
  	if (err)
  		goto out_undo_insn;
  
  	err = -ENOMEM;
  	func = kcalloc(env->subprog_cnt, sizeof(prog), GFP_KERNEL);
  	if (!func)
  		goto out_undo_insn;
  
  	for (i = 0; i < env->subprog_cnt; i++) {
  		subprog_start = subprog_end;
  		subprog_end = env->subprog_info[i + 1].start;
  
  		len = subprog_end - subprog_start;
  		/* bpf_prog_run() doesn't call subprogs directly,
  		 * hence main prog stats include the runtime of subprogs.
  		 * subprogs don't have IDs and not reachable via prog_get_next_id
  		 * func[i]->stats will never be accessed and stays NULL
  		 */
  		func[i] = bpf_prog_alloc_no_stats(bpf_prog_size(len), GFP_USER);
  		if (!func[i])
  			goto out_free;
  		memcpy(func[i]->insnsi, &prog->insnsi[subprog_start],
  		       len * sizeof(struct bpf_insn));
  		func[i]->type = prog->type;
  		func[i]->len = len;
  		if (bpf_prog_calc_tag(func[i]))
  			goto out_free;
  		func[i]->is_func = 1;
  		func[i]->aux->func_idx = i;
  		/* Below members will be freed only at prog->aux */
  		func[i]->aux->btf = prog->aux->btf;
  		func[i]->aux->func_info = prog->aux->func_info;
  		func[i]->aux->poke_tab = prog->aux->poke_tab;
  		func[i]->aux->size_poke_tab = prog->aux->size_poke_tab;
  
  		for (j = 0; j < prog->aux->size_poke_tab; j++) {
  			struct bpf_jit_poke_descriptor *poke;
  
  			poke = &prog->aux->poke_tab[j];
  			if (poke->insn_idx < subprog_end &&
  			    poke->insn_idx >= subprog_start)
  				poke->aux = func[i]->aux;
  		}
  
  		/* Use bpf_prog_F_tag to indicate functions in stack traces.
  		 * Long term would need debug info to populate names
  		 */
  		func[i]->aux->name[0] = 'F';
  		func[i]->aux->stack_depth = env->subprog_info[i].stack_depth;
  		func[i]->jit_requested = 1;
  		func[i]->blinding_requested = prog->blinding_requested;
  		func[i]->aux->kfunc_tab = prog->aux->kfunc_tab;
  		func[i]->aux->kfunc_btf_tab = prog->aux->kfunc_btf_tab;
  		func[i]->aux->linfo = prog->aux->linfo;
  		func[i]->aux->nr_linfo = prog->aux->nr_linfo;
  		func[i]->aux->jited_linfo = prog->aux->jited_linfo;
  		func[i]->aux->linfo_idx = env->subprog_info[i].linfo_idx;
  		num_exentries = 0;
  		insn = func[i]->insnsi;
  		for (j = 0; j < func[i]->len; j++, insn++) {
  			if (BPF_CLASS(insn->code) == BPF_LDX &&
  			    BPF_MODE(insn->code) == BPF_PROBE_MEM)
  				num_exentries++;
  		}
  		func[i]->aux->num_exentries = num_exentries;
  		func[i]->aux->tail_call_reachable = env->subprog_info[i].tail_call_reachable;
  		func[i] = bpf_int_jit_compile(func[i]);
  		if (!func[i]->jited) {
  			err = -ENOTSUPP;
  			goto out_free;
  		}
  		cond_resched();
  	}
  
  	/* at this point all bpf functions were successfully JITed
  	 * now populate all bpf_calls with correct addresses and
  	 * run last pass of JIT
  	 */
  	for (i = 0; i < env->subprog_cnt; i++) {
  		insn = func[i]->insnsi;
  		for (j = 0; j < func[i]->len; j++, insn++) {
  			if (bpf_pseudo_func(insn)) {
  				subprog = insn->off;
  				insn[0].imm = (u32)(long)func[subprog]->bpf_func;
  				insn[1].imm = ((u64)(long)func[subprog]->bpf_func) >> 32;
  				continue;
  			}
  			if (!bpf_pseudo_call(insn))
  				continue;
  			subprog = insn->off;
  			insn->imm = BPF_CALL_IMM(func[subprog]->bpf_func);
  		}
  
  		/* we use the aux data to keep a list of the start addresses
  		 * of the JITed images for each function in the program
  		 *
  		 * for some architectures, such as powerpc64, the imm field
  		 * might not be large enough to hold the offset of the start
  		 * address of the callee's JITed image from __bpf_call_base
  		 *
  		 * in such cases, we can lookup the start address of a callee
  		 * by using its subprog id, available from the off field of
  		 * the call instruction, as an index for this list
  		 */
  		func[i]->aux->func = func;
  		func[i]->aux->func_cnt = env->subprog_cnt;
  	}
  	for (i = 0; i < env->subprog_cnt; i++) {
  		old_bpf_func = func[i]->bpf_func;
  		tmp = bpf_int_jit_compile(func[i]);
  		if (tmp != func[i] || func[i]->bpf_func != old_bpf_func) {
  			verbose(env, "JIT doesn't support bpf-to-bpf calls\n");
  			err = -ENOTSUPP;
  			goto out_free;
  		}
  		cond_resched();
  	}
  
  	/* finally lock prog and jit images for all functions and
  	 * populate kallsysm
  	 */
  	for (i = 0; i < env->subprog_cnt; i++) {
  		bpf_prog_lock_ro(func[i]);
  		bpf_prog_kallsyms_add(func[i]);
  	}
  
  	/* Last step: make now unused interpreter insns from main
  	 * prog consistent for later dump requests, so they can
  	 * later look the same as if they were interpreted only.
  	 */
  	for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
  		if (bpf_pseudo_func(insn)) {
  			insn[0].imm = env->insn_aux_data[i].call_imm;
  			insn[1].imm = insn->off;
  			insn->off = 0;
  			continue;
  		}
  		if (!bpf_pseudo_call(insn))
  			continue;
  		insn->off = env->insn_aux_data[i].call_imm;
  		subprog = find_subprog(env, i + insn->off + 1);
  		insn->imm = subprog;
  	}
  
  	prog->jited = 1;
  	prog->bpf_func = func[0]->bpf_func;
  	prog->jited_len = func[0]->jited_len;
  	prog->aux->func = func;
  	prog->aux->func_cnt = env->subprog_cnt;
  	bpf_prog_jit_attempt_done(prog);
  	return 0;
  out_free:
  	/* We failed JIT'ing, so at this point we need to unregister poke
  	 * descriptors from subprogs, so that kernel is not attempting to
  	 * patch it anymore as we're freeing the subprog JIT memory.
  	 */
  	for (i = 0; i < prog->aux->size_poke_tab; i++) {
  		map_ptr = prog->aux->poke_tab[i].tail_call.map;
  		map_ptr->ops->map_poke_untrack(map_ptr, prog->aux);
  	}
  	/* At this point we're guaranteed that poke descriptors are not
  	 * live anymore. We can just unlink its descriptor table as it's
  	 * released with the main prog.
  	 */
  	for (i = 0; i < env->subprog_cnt; i++) {
  		if (!func[i])
  			continue;
  		func[i]->aux->poke_tab = NULL;
  		bpf_jit_free(func[i]);
  	}
  	kfree(func);
  out_undo_insn:
  	/* cleanup main prog to be interpreted */
  	prog->jit_requested = 0;
  	prog->blinding_requested = 0;
  	for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
  		if (!bpf_pseudo_call(insn))
  			continue;
  		insn->off = 0;
  		insn->imm = env->insn_aux_data[i].call_imm;
  	}
  	bpf_prog_jit_attempt_done(prog);
  	return err;
  }
  
  static int fixup_call_args(struct bpf_verifier_env *env)
  {
  #ifndef CONFIG_BPF_JIT_ALWAYS_ON
  	struct bpf_prog *prog = env->prog;
  	struct bpf_insn *insn = prog->insnsi;
  	bool has_kfunc_call = bpf_prog_has_kfunc_call(prog);
  	int i, depth;
  #endif
  	int err = 0;
  
  	if (env->prog->jit_requested &&
  	    !bpf_prog_is_dev_bound(env->prog->aux)) {
  		err = jit_subprogs(env);
  		if (err == 0)
  			return 0;
  		if (err == -EFAULT)
  			return err;
  	}
  #ifndef CONFIG_BPF_JIT_ALWAYS_ON
  	if (has_kfunc_call) {
  		verbose(env, "calling kernel functions are not allowed in non-JITed programs\n");
  		return -EINVAL;
  	}
  	if (env->subprog_cnt > 1 && env->prog->aux->tail_call_reachable) {
  		/* When JIT fails the progs with bpf2bpf calls and tail_calls
  		 * have to be rejected, since interpreter doesn't support them yet.
  		 */
  		verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
  		return -EINVAL;
  	}
  	for (i = 0; i < prog->len; i++, insn++) {
  		if (bpf_pseudo_func(insn)) {
  			/* When JIT fails the progs with callback calls
  			 * have to be rejected, since interpreter doesn't support them yet.
  			 */
  			verbose(env, "callbacks are not allowed in non-JITed programs\n");
  			return -EINVAL;
  		}
  
  		if (!bpf_pseudo_call(insn))
  			continue;
  		depth = get_callee_stack_depth(env, insn, i);
  		if (depth < 0)
  			return depth;
  		bpf_patch_call_args(insn, depth);
  	}
  	err = 0;
  #endif
  	return err;
  }
  
  static int fixup_kfunc_call(struct bpf_verifier_env *env,
  			    struct bpf_insn *insn)
  {
  	const struct bpf_kfunc_desc *desc;
  
  	if (!insn->imm) {
  		verbose(env, "invalid kernel function call not eliminated in verifier pass\n");
  		return -EINVAL;
  	}
  
  	/* insn->imm has the btf func_id. Replace it with
  	 * an address (relative to __bpf_base_call).
  	 */
  	desc = find_kfunc_desc(env->prog, insn->imm, insn->off);
  	if (!desc) {
  		verbose(env, "verifier internal error: kernel function descriptor not found for func_id %u\n",
  			insn->imm);
  		return -EFAULT;
  	}
  
  	insn->imm = desc->imm;
  
  	return 0;
  }
  
  /* Do various post-verification rewrites in a single program pass.
   * These rewrites simplify JIT and interpreter implementations.
   */
  static int do_misc_fixups(struct bpf_verifier_env *env)
  {
  	struct bpf_prog *prog = env->prog;
  	enum bpf_attach_type eatype = prog->expected_attach_type;
  	enum bpf_prog_type prog_type = resolve_prog_type(prog);
  	struct bpf_insn *insn = prog->insnsi;
  	const struct bpf_func_proto *fn;
  	const int insn_cnt = prog->len;
  	const struct bpf_map_ops *ops;
  	struct bpf_insn_aux_data *aux;
  	struct bpf_insn insn_buf[16];
  	struct bpf_prog *new_prog;
  	struct bpf_map *map_ptr;
  	int i, ret, cnt, delta = 0;
  
  	for (i = 0; i < insn_cnt; i++, insn++) {
  		/* Make divide-by-zero exceptions impossible. */
  		if (insn->code == (BPF_ALU64 | BPF_MOD | BPF_X) ||
  		    insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) ||
  		    insn->code == (BPF_ALU | BPF_MOD | BPF_X) ||
  		    insn->code == (BPF_ALU | BPF_DIV | BPF_X)) {
  			bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
  			bool isdiv = BPF_OP(insn->code) == BPF_DIV;
  			struct bpf_insn *patchlet;
  			struct bpf_insn chk_and_div[] = {
  				/* [R,W]x div 0 -> 0 */
  				BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
  					     BPF_JNE | BPF_K, insn->src_reg,
  					     0, 2, 0),
  				BPF_ALU32_REG(BPF_XOR, insn->dst_reg, insn->dst_reg),
  				BPF_JMP_IMM(BPF_JA, 0, 0, 1),
  				*insn,
  			};
  			struct bpf_insn chk_and_mod[] = {
  				/* [R,W]x mod 0 -> [R,W]x */
  				BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
  					     BPF_JEQ | BPF_K, insn->src_reg,
  					     0, 1 + (is64 ? 0 : 1), 0),
  				*insn,
  				BPF_JMP_IMM(BPF_JA, 0, 0, 1),
  				BPF_MOV32_REG(insn->dst_reg, insn->dst_reg),
  			};
  
  			patchlet = isdiv ? chk_and_div : chk_and_mod;
  			cnt = isdiv ? ARRAY_SIZE(chk_and_div) :
  				      ARRAY_SIZE(chk_and_mod) - (is64 ? 2 : 0);
  
  			new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt);
  			if (!new_prog)
  				return -ENOMEM;
  
  			delta    += cnt - 1;
  			env->prog = prog = new_prog;
  			insn      = new_prog->insnsi + i + delta;
  			continue;
  		}
  
  		/* Implement LD_ABS and LD_IND with a rewrite, if supported by the program type. */
  		if (BPF_CLASS(insn->code) == BPF_LD &&
  		    (BPF_MODE(insn->code) == BPF_ABS ||
  		     BPF_MODE(insn->code) == BPF_IND)) {
  			cnt = env->ops->gen_ld_abs(insn, insn_buf);
  			if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
  				verbose(env, "bpf verifier is misconfigured\n");
  				return -EINVAL;
  			}
  
  			new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
  			if (!new_prog)
  				return -ENOMEM;
  
  			delta    += cnt - 1;
  			env->prog = prog = new_prog;
  			insn      = new_prog->insnsi + i + delta;
  			continue;
  		}
  
  		/* Rewrite pointer arithmetic to mitigate speculation attacks. */
  		if (insn->code == (BPF_ALU64 | BPF_ADD | BPF_X) ||
  		    insn->code == (BPF_ALU64 | BPF_SUB | BPF_X)) {
  			const u8 code_add = BPF_ALU64 | BPF_ADD | BPF_X;
  			const u8 code_sub = BPF_ALU64 | BPF_SUB | BPF_X;
  			struct bpf_insn *patch = &insn_buf[0];
  			bool issrc, isneg, isimm;
  			u32 off_reg;
  
  			aux = &env->insn_aux_data[i + delta];
  			if (!aux->alu_state ||
  			    aux->alu_state == BPF_ALU_NON_POINTER)
  				continue;
  
  			isneg = aux->alu_state & BPF_ALU_NEG_VALUE;
  			issrc = (aux->alu_state & BPF_ALU_SANITIZE) ==
  				BPF_ALU_SANITIZE_SRC;
  			isimm = aux->alu_state & BPF_ALU_IMMEDIATE;
  
  			off_reg = issrc ? insn->src_reg : insn->dst_reg;
  			if (isimm) {
  				*patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit);
  			} else {
  				if (isneg)
  					*patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
  				*patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit);
  				*patch++ = BPF_ALU64_REG(BPF_SUB, BPF_REG_AX, off_reg);
  				*patch++ = BPF_ALU64_REG(BPF_OR, BPF_REG_AX, off_reg);
  				*patch++ = BPF_ALU64_IMM(BPF_NEG, BPF_REG_AX, 0);
  				*patch++ = BPF_ALU64_IMM(BPF_ARSH, BPF_REG_AX, 63);
  				*patch++ = BPF_ALU64_REG(BPF_AND, BPF_REG_AX, off_reg);
  			}
  			if (!issrc)
  				*patch++ = BPF_MOV64_REG(insn->dst_reg, insn->src_reg);
  			insn->src_reg = BPF_REG_AX;
  			if (isneg)
  				insn->code = insn->code == code_add ?
  					     code_sub : code_add;
  			*patch++ = *insn;
  			if (issrc && isneg && !isimm)
  				*patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
  			cnt = patch - insn_buf;
  
  			new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
  			if (!new_prog)
  				return -ENOMEM;
  
  			delta    += cnt - 1;
  			env->prog = prog = new_prog;
  			insn      = new_prog->insnsi + i + delta;
  			continue;
  		}
  
  		if (insn->code != (BPF_JMP | BPF_CALL))
  			continue;
  		if (insn->src_reg == BPF_PSEUDO_CALL)
  			continue;
  		if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) {
  			ret = fixup_kfunc_call(env, insn);
  			if (ret)
  				return ret;
  			continue;
  		}
  
  		if (insn->imm == BPF_FUNC_get_route_realm)
  			prog->dst_needed = 1;
  		if (insn->imm == BPF_FUNC_get_prandom_u32)
  			bpf_user_rnd_init_once();
  		if (insn->imm == BPF_FUNC_override_return)
  			prog->kprobe_override = 1;
  		if (insn->imm == BPF_FUNC_tail_call) {
  			/* If we tail call into other programs, we
  			 * cannot make any assumptions since they can
  			 * be replaced dynamically during runtime in
  			 * the program array.
  			 */
  			prog->cb_access = 1;
  			if (!allow_tail_call_in_subprogs(env))
  				prog->aux->stack_depth = MAX_BPF_STACK;
  			prog->aux->max_pkt_offset = MAX_PACKET_OFF;
  
  			/* mark bpf_tail_call as different opcode to avoid
  			 * conditional branch in the interpreter for every normal
  			 * call and to prevent accidental JITing by JIT compiler
  			 * that doesn't support bpf_tail_call yet
  			 */
  			insn->imm = 0;
  			insn->code = BPF_JMP | BPF_TAIL_CALL;
  
  			aux = &env->insn_aux_data[i + delta];
  			if (env->bpf_capable && !prog->blinding_requested &&
  			    prog->jit_requested &&
  			    !bpf_map_key_poisoned(aux) &&
  			    !bpf_map_ptr_poisoned(aux) &&
  			    !bpf_map_ptr_unpriv(aux)) {
  				struct bpf_jit_poke_descriptor desc = {
  					.reason = BPF_POKE_REASON_TAIL_CALL,
  					.tail_call.map = BPF_MAP_PTR(aux->map_ptr_state),
  					.tail_call.key = bpf_map_key_immediate(aux),
  					.insn_idx = i + delta,
  				};
  
  				ret = bpf_jit_add_poke_descriptor(prog, &desc);
  				if (ret < 0) {
  					verbose(env, "adding tail call poke descriptor failed\n");
  					return ret;
  				}
  
  				insn->imm = ret + 1;
  				continue;
  			}
  
  			if (!bpf_map_ptr_unpriv(aux))
  				continue;
  
  			/* instead of changing every JIT dealing with tail_call
  			 * emit two extra insns:
  			 * if (index >= max_entries) goto out;
  			 * index &= array->index_mask;
  			 * to avoid out-of-bounds cpu speculation
  			 */
  			if (bpf_map_ptr_poisoned(aux)) {
  				verbose(env, "tail_call abusing map_ptr\n");
  				return -EINVAL;
  			}
  
  			map_ptr = BPF_MAP_PTR(aux->map_ptr_state);
  			insn_buf[0] = BPF_JMP_IMM(BPF_JGE, BPF_REG_3,
  						  map_ptr->max_entries, 2);
  			insn_buf[1] = BPF_ALU32_IMM(BPF_AND, BPF_REG_3,
  						    container_of(map_ptr,
  								 struct bpf_array,
  								 map)->index_mask);
  			insn_buf[2] = *insn;
  			cnt = 3;
  			new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
  			if (!new_prog)
  				return -ENOMEM;
  
  			delta    += cnt - 1;
  			env->prog = prog = new_prog;
  			insn      = new_prog->insnsi + i + delta;
  			continue;
  		}
  
  		if (insn->imm == BPF_FUNC_timer_set_callback) {
  			/* The verifier will process callback_fn as many times as necessary
  			 * with different maps and the register states prepared by
  			 * set_timer_callback_state will be accurate.
  			 *
  			 * The following use case is valid:
  			 *   map1 is shared by prog1, prog2, prog3.
  			 *   prog1 calls bpf_timer_init for some map1 elements
  			 *   prog2 calls bpf_timer_set_callback for some map1 elements.
  			 *     Those that were not bpf_timer_init-ed will return -EINVAL.
  			 *   prog3 calls bpf_timer_start for some map1 elements.
  			 *     Those that were not both bpf_timer_init-ed and
  			 *     bpf_timer_set_callback-ed will return -EINVAL.
  			 */
  			struct bpf_insn ld_addrs[2] = {
  				BPF_LD_IMM64(BPF_REG_3, (long)prog->aux),
  			};
  
  			insn_buf[0] = ld_addrs[0];
  			insn_buf[1] = ld_addrs[1];
  			insn_buf[2] = *insn;
  			cnt = 3;
  
  			new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
  			if (!new_prog)
  				return -ENOMEM;
  
  			delta    += cnt - 1;
  			env->prog = prog = new_prog;
  			insn      = new_prog->insnsi + i + delta;
  			goto patch_call_imm;
  		}
  
  		if (insn->imm == BPF_FUNC_task_storage_get ||
  		    insn->imm == BPF_FUNC_sk_storage_get ||
  		    insn->imm == BPF_FUNC_inode_storage_get) {
  			if (env->prog->aux->sleepable)
  				insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_KERNEL);
  			else
  				insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_ATOMIC);
  			insn_buf[1] = *insn;
  			cnt = 2;
  
  			new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
  			if (!new_prog)
  				return -ENOMEM;
  
  			delta += cnt - 1;
  			env->prog = prog = new_prog;
  			insn = new_prog->insnsi + i + delta;
  			goto patch_call_imm;
  		}
  
  		/* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup
  		 * and other inlining handlers are currently limited to 64 bit
  		 * only.
  		 */
  		if (prog->jit_requested && BITS_PER_LONG == 64 &&
  		    (insn->imm == BPF_FUNC_map_lookup_elem ||
  		     insn->imm == BPF_FUNC_map_update_elem ||
  		     insn->imm == BPF_FUNC_map_delete_elem ||
  		     insn->imm == BPF_FUNC_map_push_elem   ||
  		     insn->imm == BPF_FUNC_map_pop_elem    ||
  		     insn->imm == BPF_FUNC_map_peek_elem   ||
  		     insn->imm == BPF_FUNC_redirect_map    ||
  		     insn->imm == BPF_FUNC_for_each_map_elem)) {
  			aux = &env->insn_aux_data[i + delta];
  			if (bpf_map_ptr_poisoned(aux))
  				goto patch_call_imm;
  
  			map_ptr = BPF_MAP_PTR(aux->map_ptr_state);
  			ops = map_ptr->ops;
  			if (insn->imm == BPF_FUNC_map_lookup_elem &&
  			    ops->map_gen_lookup) {
  				cnt = ops->map_gen_lookup(map_ptr, insn_buf);
  				if (cnt == -EOPNOTSUPP)
  					goto patch_map_ops_generic;
  				if (cnt <= 0 || cnt >= ARRAY_SIZE(insn_buf)) {
  					verbose(env, "bpf verifier is misconfigured\n");
  					return -EINVAL;
  				}
  
  				new_prog = bpf_patch_insn_data(env, i + delta,
  							       insn_buf, cnt);
  				if (!new_prog)
  					return -ENOMEM;
  
  				delta    += cnt - 1;
  				env->prog = prog = new_prog;
  				insn      = new_prog->insnsi + i + delta;
  				continue;
  			}
  
  			BUILD_BUG_ON(!__same_type(ops->map_lookup_elem,
  				     (void *(*)(struct bpf_map *map, void *key))NULL));
  			BUILD_BUG_ON(!__same_type(ops->map_delete_elem,
  				     (int (*)(struct bpf_map *map, void *key))NULL));
  			BUILD_BUG_ON(!__same_type(ops->map_update_elem,
  				     (int (*)(struct bpf_map *map, void *key, void *value,
  					      u64 flags))NULL));
  			BUILD_BUG_ON(!__same_type(ops->map_push_elem,
  				     (int (*)(struct bpf_map *map, void *value,
  					      u64 flags))NULL));
  			BUILD_BUG_ON(!__same_type(ops->map_pop_elem,
  				     (int (*)(struct bpf_map *map, void *value))NULL));
  			BUILD_BUG_ON(!__same_type(ops->map_peek_elem,
  				     (int (*)(struct bpf_map *map, void *value))NULL));
  			BUILD_BUG_ON(!__same_type(ops->map_redirect,
  				     (int (*)(struct bpf_map *map, u32 ifindex, u64 flags))NULL));
  			BUILD_BUG_ON(!__same_type(ops->map_for_each_callback,
  				     (int (*)(struct bpf_map *map,
  					      bpf_callback_t callback_fn,
  					      void *callback_ctx,
  					      u64 flags))NULL));
  
  patch_map_ops_generic:
  			switch (insn->imm) {
  			case BPF_FUNC_map_lookup_elem:
  				insn->imm = BPF_CALL_IMM(ops->map_lookup_elem);
  				continue;
  			case BPF_FUNC_map_update_elem:
  				insn->imm = BPF_CALL_IMM(ops->map_update_elem);
  				continue;
  			case BPF_FUNC_map_delete_elem:
  				insn->imm = BPF_CALL_IMM(ops->map_delete_elem);
  				continue;
  			case BPF_FUNC_map_push_elem:
  				insn->imm = BPF_CALL_IMM(ops->map_push_elem);
  				continue;
  			case BPF_FUNC_map_pop_elem:
  				insn->imm = BPF_CALL_IMM(ops->map_pop_elem);
  				continue;
  			case BPF_FUNC_map_peek_elem:
  				insn->imm = BPF_CALL_IMM(ops->map_peek_elem);
  				continue;
  			case BPF_FUNC_redirect_map:
  				insn->imm = BPF_CALL_IMM(ops->map_redirect);
  				continue;
  			case BPF_FUNC_for_each_map_elem:
  				insn->imm = BPF_CALL_IMM(ops->map_for_each_callback);
  				continue;
  			}
  
  			goto patch_call_imm;
  		}
  
  		/* Implement bpf_jiffies64 inline. */
  		if (prog->jit_requested && BITS_PER_LONG == 64 &&
  		    insn->imm == BPF_FUNC_jiffies64) {
  			struct bpf_insn ld_jiffies_addr[2] = {
  				BPF_LD_IMM64(BPF_REG_0,
  					     (unsigned long)&jiffies),
  			};
  
  			insn_buf[0] = ld_jiffies_addr[0];
  			insn_buf[1] = ld_jiffies_addr[1];
  			insn_buf[2] = BPF_LDX_MEM(BPF_DW, BPF_REG_0,
  						  BPF_REG_0, 0);
  			cnt = 3;
  
  			new_prog = bpf_patch_insn_data(env, i + delta, insn_buf,
  						       cnt);
  			if (!new_prog)
  				return -ENOMEM;
  
  			delta    += cnt - 1;
  			env->prog = prog = new_prog;
  			insn      = new_prog->insnsi + i + delta;
  			continue;
  		}
  
  		/* Implement bpf_get_func_arg inline. */
  		if (prog_type == BPF_PROG_TYPE_TRACING &&
  		    insn->imm == BPF_FUNC_get_func_arg) {
  			/* Load nr_args from ctx - 8 */
  			insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
  			insn_buf[1] = BPF_JMP32_REG(BPF_JGE, BPF_REG_2, BPF_REG_0, 6);
  			insn_buf[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_2, 3);
  			insn_buf[3] = BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_1);
  			insn_buf[4] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_2, 0);
  			insn_buf[5] = BPF_STX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, 0);
  			insn_buf[6] = BPF_MOV64_IMM(BPF_REG_0, 0);
  			insn_buf[7] = BPF_JMP_A(1);
  			insn_buf[8] = BPF_MOV64_IMM(BPF_REG_0, -EINVAL);
  			cnt = 9;
  
  			new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
  			if (!new_prog)
  				return -ENOMEM;
  
  			delta    += cnt - 1;
  			env->prog = prog = new_prog;
  			insn      = new_prog->insnsi + i + delta;
  			continue;
  		}
  
  		/* Implement bpf_get_func_ret inline. */
  		if (prog_type == BPF_PROG_TYPE_TRACING &&
  		    insn->imm == BPF_FUNC_get_func_ret) {
  			if (eatype == BPF_TRACE_FEXIT ||
  			    eatype == BPF_MODIFY_RETURN) {
  				/* Load nr_args from ctx - 8 */
  				insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
  				insn_buf[1] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_0, 3);
  				insn_buf[2] = BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1);
  				insn_buf[3] = BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, 0);
  				insn_buf[4] = BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_3, 0);
  				insn_buf[5] = BPF_MOV64_IMM(BPF_REG_0, 0);
  				cnt = 6;
  			} else {
  				insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, -EOPNOTSUPP);
  				cnt = 1;
  			}
  
  			new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
  			if (!new_prog)
  				return -ENOMEM;
  
  			delta    += cnt - 1;
  			env->prog = prog = new_prog;
  			insn      = new_prog->insnsi + i + delta;
  			continue;
  		}
  
  		/* Implement get_func_arg_cnt inline. */
  		if (prog_type == BPF_PROG_TYPE_TRACING &&
  		    insn->imm == BPF_FUNC_get_func_arg_cnt) {
  			/* Load nr_args from ctx - 8 */
  			insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
  
  			new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1);
  			if (!new_prog)
  				return -ENOMEM;
  
  			env->prog = prog = new_prog;
  			insn      = new_prog->insnsi + i + delta;
  			continue;
  		}
  
  		/* Implement bpf_get_func_ip inline. */
  		if (prog_type == BPF_PROG_TYPE_TRACING &&
  		    insn->imm == BPF_FUNC_get_func_ip) {
  			/* Load IP address from ctx - 16 */
  			insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -16);
  
  			new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1);
  			if (!new_prog)
  				return -ENOMEM;
  
  			env->prog = prog = new_prog;
  			insn      = new_prog->insnsi + i + delta;
  			continue;
  		}
  
  patch_call_imm:
  		fn = env->ops->get_func_proto(insn->imm, env->prog);
  		/* all functions that have prototype and verifier allowed
  		 * programs to call them, must be real in-kernel functions
  		 */
  		if (!fn->func) {
  			verbose(env,
  				"kernel subsystem misconfigured func %s#%d\n",
  				func_id_name(insn->imm), insn->imm);
  			return -EFAULT;
  		}
  		insn->imm = fn->func - __bpf_call_base;
  	}
  
  	/* Since poke tab is now finalized, publish aux to tracker. */
  	for (i = 0; i < prog->aux->size_poke_tab; i++) {
  		map_ptr = prog->aux->poke_tab[i].tail_call.map;
  		if (!map_ptr->ops->map_poke_track ||
  		    !map_ptr->ops->map_poke_untrack ||
  		    !map_ptr->ops->map_poke_run) {
  			verbose(env, "bpf verifier is misconfigured\n");
  			return -EINVAL;
  		}
  
  		ret = map_ptr->ops->map_poke_track(map_ptr, prog->aux);
  		if (ret < 0) {
  			verbose(env, "tracking tail call prog failed\n");
  			return ret;
  		}
  	}
  
  	sort_kfunc_descs_by_imm(env->prog);
  
  	return 0;
  }
  
  static void free_states(struct bpf_verifier_env *env)
  {
  	struct bpf_verifier_state_list *sl, *sln;
  	int i;
  
  	sl = env->free_list;
  	while (sl) {
  		sln = sl->next;
  		free_verifier_state(&sl->state, false);
  		kfree(sl);
  		sl = sln;
  	}
  	env->free_list = NULL;
  
  	if (!env->explored_states)
  		return;
  
  	for (i = 0; i < state_htab_size(env); i++) {
  		sl = env->explored_states[i];
  
  		while (sl) {
  			sln = sl->next;
  			free_verifier_state(&sl->state, false);
  			kfree(sl);
  			sl = sln;
  		}
  		env->explored_states[i] = NULL;
  	}
  }
  
  static int do_check_common(struct bpf_verifier_env *env, int subprog)
  {
  	bool pop_log = !(env->log.level & BPF_LOG_LEVEL2);
  	struct bpf_verifier_state *state;
  	struct bpf_reg_state *regs;
  	int ret, i;
  
  	env->prev_linfo = NULL;
  	env->pass_cnt++;
  
  	state = kzalloc(sizeof(struct bpf_verifier_state), GFP_KERNEL);
  	if (!state)
  		return -ENOMEM;
  	state->curframe = 0;
  	state->speculative = false;
  	state->branches = 1;
  	state->frame[0] = kzalloc(sizeof(struct bpf_func_state), GFP_KERNEL);
  	if (!state->frame[0]) {
  		kfree(state);
  		return -ENOMEM;
  	}
  	env->cur_state = state;
  	init_func_state(env, state->frame[0],
  			BPF_MAIN_FUNC /* callsite */,
  			0 /* frameno */,
  			subprog);
  
  	regs = state->frame[state->curframe]->regs;
  	if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) {
  		ret = btf_prepare_func_args(env, subprog, regs);
  		if (ret)
  			goto out;
  		for (i = BPF_REG_1; i <= BPF_REG_5; i++) {
  			if (regs[i].type == PTR_TO_CTX)
  				mark_reg_known_zero(env, regs, i);
  			else if (regs[i].type == SCALAR_VALUE)
  				mark_reg_unknown(env, regs, i);
  			else if (base_type(regs[i].type) == PTR_TO_MEM) {
  				const u32 mem_size = regs[i].mem_size;
  
  				mark_reg_known_zero(env, regs, i);
  				regs[i].mem_size = mem_size;
  				regs[i].id = ++env->id_gen;
  			}
  		}
  	} else {
  		/* 1st arg to a function */
  		regs[BPF_REG_1].type = PTR_TO_CTX;
  		mark_reg_known_zero(env, regs, BPF_REG_1);
  		ret = btf_check_subprog_arg_match(env, subprog, regs);
  		if (ret == -EFAULT)
  			/* unlikely verifier bug. abort.
  			 * ret == 0 and ret < 0 are sadly acceptable for
  			 * main() function due to backward compatibility.
  			 * Like socket filter program may be written as:
  			 * int bpf_prog(struct pt_regs *ctx)
  			 * and never dereference that ctx in the program.
  			 * 'struct pt_regs' is a type mismatch for socket
  			 * filter that should be using 'struct __sk_buff'.
  			 */
  			goto out;
  	}
  
  	ret = do_check(env);
  out:
  	/* check for NULL is necessary, since cur_state can be freed inside
  	 * do_check() under memory pressure.
  	 */
  	if (env->cur_state) {
  		free_verifier_state(env->cur_state, true);
  		env->cur_state = NULL;
  	}
  	while (!pop_stack(env, NULL, NULL, false));
  	if (!ret && pop_log)
  		bpf_vlog_reset(&env->log, 0);
  	free_states(env);
  	return ret;
  }
  
  /* Verify all global functions in a BPF program one by one based on their BTF.
   * All global functions must pass verification. Otherwise the whole program is rejected.
   * Consider:
   * int bar(int);
   * int foo(int f)
   * {
   *    return bar(f);
   * }
   * int bar(int b)
   * {
   *    ...
   * }
   * foo() will be verified first for R1=any_scalar_value. During verification it
   * will be assumed that bar() already verified successfully and call to bar()
   * from foo() will be checked for type match only. Later bar() will be verified
   * independently to check that it's safe for R1=any_scalar_value.
   */
  static int do_check_subprogs(struct bpf_verifier_env *env)
  {
  	struct bpf_prog_aux *aux = env->prog->aux;
  	int i, ret;
  
  	if (!aux->func_info)
  		return 0;
  
  	for (i = 1; i < env->subprog_cnt; i++) {
  		if (aux->func_info_aux[i].linkage != BTF_FUNC_GLOBAL)
  			continue;
  		env->insn_idx = env->subprog_info[i].start;
  		WARN_ON_ONCE(env->insn_idx == 0);
  		ret = do_check_common(env, i);
  		if (ret) {
  			return ret;
  		} else if (env->log.level & BPF_LOG_LEVEL) {
  			verbose(env,
  				"Func#%d is safe for any args that match its prototype\n",
  				i);
  		}
  	}
  	return 0;
  }
  
  static int do_check_main(struct bpf_verifier_env *env)
  {
  	int ret;
  
  	env->insn_idx = 0;
  	ret = do_check_common(env, 0);
  	if (!ret)
  		env->prog->aux->stack_depth = env->subprog_info[0].stack_depth;
  	return ret;
  }
  
  
  static void print_verification_stats(struct bpf_verifier_env *env)
  {
  	int i;
  
  	if (env->log.level & BPF_LOG_STATS) {
  		verbose(env, "verification time %lld usec\n",
  			div_u64(env->verification_time, 1000));
  		verbose(env, "stack depth ");
  		for (i = 0; i < env->subprog_cnt; i++) {
  			u32 depth = env->subprog_info[i].stack_depth;
  
  			verbose(env, "%d", depth);
  			if (i + 1 < env->subprog_cnt)
  				verbose(env, "+");
  		}
  		verbose(env, "\n");
  	}
  	verbose(env, "processed %d insns (limit %d) max_states_per_insn %d "
  		"total_states %d peak_states %d mark_read %d\n",
  		env->insn_processed, BPF_COMPLEXITY_LIMIT_INSNS,
  		env->max_states_per_insn, env->total_states,
  		env->peak_states, env->longest_mark_read_walk);
  }
  
  static int check_struct_ops_btf_id(struct bpf_verifier_env *env)
  {
  	const struct btf_type *t, *func_proto;
  	const struct bpf_struct_ops *st_ops;
  	const struct btf_member *member;
  	struct bpf_prog *prog = env->prog;
  	u32 btf_id, member_idx;
  	const char *mname;
  
  	if (!prog->gpl_compatible) {
  		verbose(env, "struct ops programs must have a GPL compatible license\n");
  		return -EINVAL;
  	}
  
  	btf_id = prog->aux->attach_btf_id;
  	st_ops = bpf_struct_ops_find(btf_id);
  	if (!st_ops) {
  		verbose(env, "attach_btf_id %u is not a supported struct\n",
  			btf_id);
  		return -ENOTSUPP;
  	}
  
  	t = st_ops->type;
  	member_idx = prog->expected_attach_type;
  	if (member_idx >= btf_type_vlen(t)) {
  		verbose(env, "attach to invalid member idx %u of struct %s\n",
  			member_idx, st_ops->name);
  		return -EINVAL;
  	}
  
  	member = &btf_type_member(t)[member_idx];
  	mname = btf_name_by_offset(btf_vmlinux, member->name_off);
  	func_proto = btf_type_resolve_func_ptr(btf_vmlinux, member->type,
  					       NULL);
  	if (!func_proto) {
  		verbose(env, "attach to invalid member %s(@idx %u) of struct %s\n",
  			mname, member_idx, st_ops->name);
  		return -EINVAL;
  	}
  
  	if (st_ops->check_member) {
  		int err = st_ops->check_member(t, member);
  
  		if (err) {
  			verbose(env, "attach to unsupported member %s of struct %s\n",
  				mname, st_ops->name);
  			return err;
  		}
  	}
  
  	prog->aux->attach_func_proto = func_proto;
  	prog->aux->attach_func_name = mname;
  	env->ops = st_ops->verifier_ops;
  
  	return 0;
  }
  #define SECURITY_PREFIX "security_"
  
  static int check_attach_modify_return(unsigned long addr, const char *func_name)
  {
  	if (within_error_injection_list(addr) ||
  	    !strncmp(SECURITY_PREFIX, func_name, sizeof(SECURITY_PREFIX) - 1))
  		return 0;
  
  	return -EINVAL;
  }
  
  /* list of non-sleepable functions that are otherwise on
   * ALLOW_ERROR_INJECTION list
   */
  BTF_SET_START(btf_non_sleepable_error_inject)
  /* Three functions below can be called from sleepable and non-sleepable context.
   * Assume non-sleepable from bpf safety point of view.
   */
  BTF_ID(func, __filemap_add_folio)
  BTF_ID(func, should_fail_alloc_page)
  BTF_ID(func, should_failslab)
  BTF_SET_END(btf_non_sleepable_error_inject)
  
  static int check_non_sleepable_error_inject(u32 btf_id)
  {
  	return btf_id_set_contains(&btf_non_sleepable_error_inject, btf_id);
  }
  
  int bpf_check_attach_target(struct bpf_verifier_log *log,
  			    const struct bpf_prog *prog,
  			    const struct bpf_prog *tgt_prog,
  			    u32 btf_id,
  			    struct bpf_attach_target_info *tgt_info)
  {
  	bool prog_extension = prog->type == BPF_PROG_TYPE_EXT;
  	const char prefix[] = "btf_trace_";
  	int ret = 0, subprog = -1, i;
  	const struct btf_type *t;
  	bool conservative = true;
  	const char *tname;
  	struct btf *btf;
  	long addr = 0;
  
  	if (!btf_id) {
  		bpf_log(log, "Tracing programs must provide btf_id\n");
  		return -EINVAL;
  	}
  	btf = tgt_prog ? tgt_prog->aux->btf : prog->aux->attach_btf;
  	if (!btf) {
  		bpf_log(log,
  			"FENTRY/FEXIT program can only be attached to another program annotated with BTF\n");
  		return -EINVAL;
  	}
  	t = btf_type_by_id(btf, btf_id);
  	if (!t) {
  		bpf_log(log, "attach_btf_id %u is invalid\n", btf_id);
  		return -EINVAL;
  	}
  	tname = btf_name_by_offset(btf, t->name_off);
  	if (!tname) {
  		bpf_log(log, "attach_btf_id %u doesn't have a name\n", btf_id);
  		return -EINVAL;
  	}
  	if (tgt_prog) {
  		struct bpf_prog_aux *aux = tgt_prog->aux;
  
  		for (i = 0; i < aux->func_info_cnt; i++)
  			if (aux->func_info[i].type_id == btf_id) {
  				subprog = i;
  				break;
  			}
  		if (subprog == -1) {
  			bpf_log(log, "Subprog %s doesn't exist\n", tname);
  			return -EINVAL;
  		}
  		conservative = aux->func_info_aux[subprog].unreliable;
  		if (prog_extension) {
  			if (conservative) {
  				bpf_log(log,
  					"Cannot replace static functions\n");
  				return -EINVAL;
  			}
  			if (!prog->jit_requested) {
  				bpf_log(log,
  					"Extension programs should be JITed\n");
  				return -EINVAL;
  			}
  		}
  		if (!tgt_prog->jited) {
  			bpf_log(log, "Can attach to only JITed progs\n");
  			return -EINVAL;
  		}
  		if (tgt_prog->type == prog->type) {
  			/* Cannot fentry/fexit another fentry/fexit program.
  			 * Cannot attach program extension to another extension.
  			 * It's ok to attach fentry/fexit to extension program.
  			 */
  			bpf_log(log, "Cannot recursively attach\n");
  			return -EINVAL;
  		}
  		if (tgt_prog->type == BPF_PROG_TYPE_TRACING &&
  		    prog_extension &&
  		    (tgt_prog->expected_attach_type == BPF_TRACE_FENTRY ||
  		     tgt_prog->expected_attach_type == BPF_TRACE_FEXIT)) {
  			/* Program extensions can extend all program types
  			 * except fentry/fexit. The reason is the following.
  			 * The fentry/fexit programs are used for performance
  			 * analysis, stats and can be attached to any program
  			 * type except themselves. When extension program is
  			 * replacing XDP function it is necessary to allow
  			 * performance analysis of all functions. Both original
  			 * XDP program and its program extension. Hence
  			 * attaching fentry/fexit to BPF_PROG_TYPE_EXT is
  			 * allowed. If extending of fentry/fexit was allowed it
  			 * would be possible to create long call chain
  			 * fentry->extension->fentry->extension beyond
  			 * reasonable stack size. Hence extending fentry is not
  			 * allowed.
  			 */
  			bpf_log(log, "Cannot extend fentry/fexit\n");
  			return -EINVAL;
  		}
  	} else {
  		if (prog_extension) {
  			bpf_log(log, "Cannot replace kernel functions\n");
  			return -EINVAL;
  		}
  	}
  
  	switch (prog->expected_attach_type) {
  	case BPF_TRACE_RAW_TP:
  		if (tgt_prog) {
  			bpf_log(log,
  				"Only FENTRY/FEXIT progs are attachable to another BPF prog\n");
  			return -EINVAL;
  		}
  		if (!btf_type_is_typedef(t)) {
  			bpf_log(log, "attach_btf_id %u is not a typedef\n",
  				btf_id);
  			return -EINVAL;
  		}
  		if (strncmp(prefix, tname, sizeof(prefix) - 1)) {
  			bpf_log(log, "attach_btf_id %u points to wrong type name %s\n",
  				btf_id, tname);
  			return -EINVAL;
  		}
  		tname += sizeof(prefix) - 1;
  		t = btf_type_by_id(btf, t->type);
  		if (!btf_type_is_ptr(t))
  			/* should never happen in valid vmlinux build */
  			return -EINVAL;
  		t = btf_type_by_id(btf, t->type);
  		if (!btf_type_is_func_proto(t))
  			/* should never happen in valid vmlinux build */
  			return -EINVAL;
  
  		break;
  	case BPF_TRACE_ITER:
  		if (!btf_type_is_func(t)) {
  			bpf_log(log, "attach_btf_id %u is not a function\n",
  				btf_id);
  			return -EINVAL;
  		}
  		t = btf_type_by_id(btf, t->type);
  		if (!btf_type_is_func_proto(t))
  			return -EINVAL;
  		ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel);
  		if (ret)
  			return ret;
  		break;
  	default:
  		if (!prog_extension)
  			return -EINVAL;
  		fallthrough;
  	case BPF_MODIFY_RETURN:
  	case BPF_LSM_MAC:
  	case BPF_TRACE_FENTRY:
  	case BPF_TRACE_FEXIT:
  		if (!btf_type_is_func(t)) {
  			bpf_log(log, "attach_btf_id %u is not a function\n",
  				btf_id);
  			return -EINVAL;
  		}
  		if (prog_extension &&
  		    btf_check_type_match(log, prog, btf, t))
  			return -EINVAL;
  		t = btf_type_by_id(btf, t->type);
  		if (!btf_type_is_func_proto(t))
  			return -EINVAL;
  
  		if ((prog->aux->saved_dst_prog_type || prog->aux->saved_dst_attach_type) &&
  		    (!tgt_prog || prog->aux->saved_dst_prog_type != tgt_prog->type ||
  		     prog->aux->saved_dst_attach_type != tgt_prog->expected_attach_type))
  			return -EINVAL;
  
  		if (tgt_prog && conservative)
  			t = NULL;
  
  		ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel);
  		if (ret < 0)
  			return ret;
  
  		if (tgt_prog) {
  			if (subprog == 0)
  				addr = (long) tgt_prog->bpf_func;
  			else
  				addr = (long) tgt_prog->aux->func[subprog]->bpf_func;
  		} else {
  			addr = kallsyms_lookup_name(tname);
  			if (!addr) {
  				bpf_log(log,
  					"The address of function %s cannot be found\n",
  					tname);
  				return -ENOENT;
  			}
  		}
  
  		if (prog->aux->sleepable) {
  			ret = -EINVAL;
  			switch (prog->type) {
  			case BPF_PROG_TYPE_TRACING:
  				/* fentry/fexit/fmod_ret progs can be sleepable only if they are
  				 * attached to ALLOW_ERROR_INJECTION and are not in denylist.
  				 */
  				if (!check_non_sleepable_error_inject(btf_id) &&
  				    within_error_injection_list(addr))
  					ret = 0;
  				break;
  			case BPF_PROG_TYPE_LSM:
  				/* LSM progs check that they are attached to bpf_lsm_*() funcs.
  				 * Only some of them are sleepable.
  				 */
  				if (bpf_lsm_is_sleepable_hook(btf_id))
  					ret = 0;
  				break;
  			default:
  				break;
  			}
  			if (ret) {
  				bpf_log(log, "%s is not sleepable\n", tname);
  				return ret;
  			}
  		} else if (prog->expected_attach_type == BPF_MODIFY_RETURN) {
  			if (tgt_prog) {
  				bpf_log(log, "can't modify return codes of BPF programs\n");
  				return -EINVAL;
  			}
  			ret = check_attach_modify_return(addr, tname);
  			if (ret) {
  				bpf_log(log, "%s() is not modifiable\n", tname);
  				return ret;
  			}
  		}
  
  		break;
  	}
  	tgt_info->tgt_addr = addr;
  	tgt_info->tgt_name = tname;
  	tgt_info->tgt_type = t;
  	return 0;
  }
  
  BTF_SET_START(btf_id_deny)
  BTF_ID_UNUSED
  #ifdef CONFIG_SMP
  BTF_ID(func, migrate_disable)
  BTF_ID(func, migrate_enable)
  #endif
  #if !defined CONFIG_PREEMPT_RCU && !defined CONFIG_TINY_RCU
  BTF_ID(func, rcu_read_unlock_strict)
  #endif
  BTF_SET_END(btf_id_deny)
  
  static int check_attach_btf_id(struct bpf_verifier_env *env)
  {
  	struct bpf_prog *prog = env->prog;
  	struct bpf_prog *tgt_prog = prog->aux->dst_prog;
  	struct bpf_attach_target_info tgt_info = {};
  	u32 btf_id = prog->aux->attach_btf_id;
  	struct bpf_trampoline *tr;
  	int ret;
  	u64 key;
  
  	if (prog->type == BPF_PROG_TYPE_SYSCALL) {
  		if (prog->aux->sleepable)
  			/* attach_btf_id checked to be zero already */
  			return 0;
  		verbose(env, "Syscall programs can only be sleepable\n");
  		return -EINVAL;
  	}
  
  	if (prog->aux->sleepable && prog->type != BPF_PROG_TYPE_TRACING &&
  	    prog->type != BPF_PROG_TYPE_LSM) {
  		verbose(env, "Only fentry/fexit/fmod_ret and lsm programs can be sleepable\n");
  		return -EINVAL;
  	}
  
  	if (prog->type == BPF_PROG_TYPE_STRUCT_OPS)
  		return check_struct_ops_btf_id(env);
  
  	if (prog->type != BPF_PROG_TYPE_TRACING &&
  	    prog->type != BPF_PROG_TYPE_LSM &&
  	    prog->type != BPF_PROG_TYPE_EXT)
  		return 0;
  
  	ret = bpf_check_attach_target(&env->log, prog, tgt_prog, btf_id, &tgt_info);
  	if (ret)
  		return ret;
  
  	if (tgt_prog && prog->type == BPF_PROG_TYPE_EXT) {
  		/* to make freplace equivalent to their targets, they need to
  		 * inherit env->ops and expected_attach_type for the rest of the
  		 * verification
  		 */
  		env->ops = bpf_verifier_ops[tgt_prog->type];
  		prog->expected_attach_type = tgt_prog->expected_attach_type;
  	}
  
  	/* store info about the attachment target that will be used later */
  	prog->aux->attach_func_proto = tgt_info.tgt_type;
  	prog->aux->attach_func_name = tgt_info.tgt_name;
  
  	if (tgt_prog) {
  		prog->aux->saved_dst_prog_type = tgt_prog->type;
  		prog->aux->saved_dst_attach_type = tgt_prog->expected_attach_type;
  	}
  
  	if (prog->expected_attach_type == BPF_TRACE_RAW_TP) {
  		prog->aux->attach_btf_trace = true;
  		return 0;
  	} else if (prog->expected_attach_type == BPF_TRACE_ITER) {
  		if (!bpf_iter_prog_supported(prog))
  			return -EINVAL;
  		return 0;
  	}
  
  	if (prog->type == BPF_PROG_TYPE_LSM) {
  		ret = bpf_lsm_verify_prog(&env->log, prog);
  		if (ret < 0)
  			return ret;
  	} else if (prog->type == BPF_PROG_TYPE_TRACING &&
  		   btf_id_set_contains(&btf_id_deny, btf_id)) {
  		return -EINVAL;
  	}
  
  	key = bpf_trampoline_compute_key(tgt_prog, prog->aux->attach_btf, btf_id);
  	tr = bpf_trampoline_get(key, &tgt_info);
  	if (!tr)
  		return -ENOMEM;
  
  	prog->aux->dst_trampoline = tr;
  	return 0;
  }
  
  struct btf *bpf_get_btf_vmlinux(void)
  {
  	if (!btf_vmlinux && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
  		mutex_lock(&bpf_verifier_lock);
  		if (!btf_vmlinux)
  			btf_vmlinux = btf_parse_vmlinux();
  		mutex_unlock(&bpf_verifier_lock);
  	}
  	return btf_vmlinux;
  }
  
  int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr)
  {
  	u64 start_time = ktime_get_ns();
  	struct bpf_verifier_env *env;
  	struct bpf_verifier_log *log;
  	int i, len, ret = -EINVAL;
  	bool is_priv;
  
  	/* no program is valid */
  	if (ARRAY_SIZE(bpf_verifier_ops) == 0)
  		return -EINVAL;
  
  	/* 'struct bpf_verifier_env' can be global, but since it's not small,
  	 * allocate/free it every time bpf_check() is called
  	 */
  	env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
  	if (!env)
  		return -ENOMEM;
  	log = &env->log;
  
  	len = (*prog)->len;
  	env->insn_aux_data =
  		vzalloc(array_size(sizeof(struct bpf_insn_aux_data), len));
  	ret = -ENOMEM;
  	if (!env->insn_aux_data)
  		goto err_free_env;
  	for (i = 0; i < len; i++)
  		env->insn_aux_data[i].orig_idx = i;
  	env->prog = *prog;
  	env->ops = bpf_verifier_ops[env->prog->type];
  	env->fd_array = make_bpfptr(attr->fd_array, uattr.is_kernel);
  	is_priv = bpf_capable();
  
  	bpf_get_btf_vmlinux();
  
  	/* grab the mutex to protect few globals used by verifier */
  	if (!is_priv)
  		mutex_lock(&bpf_verifier_lock);
  
  	if (attr->log_level || attr->log_buf || attr->log_size) {
  		/* user requested verbose verifier output
  		 * and supplied buffer to store the verification trace
  		 */
  		log->level = attr->log_level;
  		log->ubuf = (char __user *) (unsigned long) attr->log_buf;
  		log->len_total = attr->log_size;
  
  		/* log attributes have to be sane */
  		if (!bpf_verifier_log_attr_valid(log)) {
  			ret = -EINVAL;
  			goto err_unlock;
  		}
  	}
  
  	mark_verifier_state_clean(env);
  
  	if (IS_ERR(btf_vmlinux)) {
  		/* Either gcc or pahole or kernel are broken. */
  		verbose(env, "in-kernel BTF is malformed\n");
  		ret = PTR_ERR(btf_vmlinux);
  		goto skip_full_check;
  	}
  
  	env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT);
  	if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
  		env->strict_alignment = true;
  	if (attr->prog_flags & BPF_F_ANY_ALIGNMENT)
  		env->strict_alignment = false;
  
  	env->allow_ptr_leaks = bpf_allow_ptr_leaks();
  	env->allow_uninit_stack = bpf_allow_uninit_stack();
  	env->allow_ptr_to_map_access = bpf_allow_ptr_to_map_access();
  	env->bypass_spec_v1 = bpf_bypass_spec_v1();
  	env->bypass_spec_v4 = bpf_bypass_spec_v4();
  	env->bpf_capable = bpf_capable();
  
  	if (is_priv)
  		env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ;
  
  	env->explored_states = kvcalloc(state_htab_size(env),
  				       sizeof(struct bpf_verifier_state_list *),
  				       GFP_USER);
  	ret = -ENOMEM;
  	if (!env->explored_states)
  		goto skip_full_check;
  
  	ret = add_subprog_and_kfunc(env);
  	if (ret < 0)
  		goto skip_full_check;
  
  	ret = check_subprogs(env);
  	if (ret < 0)
  		goto skip_full_check;
  
  	ret = check_btf_info(env, attr, uattr);
  	if (ret < 0)
  		goto skip_full_check;
  
  	ret = check_attach_btf_id(env);
  	if (ret)
  		goto skip_full_check;
  
  	ret = resolve_pseudo_ldimm64(env);
  	if (ret < 0)
  		goto skip_full_check;
  
  	if (bpf_prog_is_dev_bound(env->prog->aux)) {
  		ret = bpf_prog_offload_verifier_prep(env->prog);
  		if (ret)
  			goto skip_full_check;
  	}
  
  	ret = check_cfg(env);
  	if (ret < 0)
  		goto skip_full_check;
  
  	ret = do_check_subprogs(env);
  	ret = ret ?: do_check_main(env);
  
  	if (ret == 0 && bpf_prog_is_dev_bound(env->prog->aux))
  		ret = bpf_prog_offload_finalize(env);
  
  skip_full_check:
  	kvfree(env->explored_states);
  
  	if (ret == 0)
  		ret = check_max_stack_depth(env);
  
  	/* instruction rewrites happen after this point */
  	if (is_priv) {
  		if (ret == 0)
  			opt_hard_wire_dead_code_branches(env);
  		if (ret == 0)
  			ret = opt_remove_dead_code(env);
  		if (ret == 0)
  			ret = opt_remove_nops(env);
  	} else {
  		if (ret == 0)
  			sanitize_dead_code(env);
  	}
  
  	if (ret == 0)
  		/* program is valid, convert *(u32*)(ctx + off) accesses */
  		ret = convert_ctx_accesses(env);
  
  	if (ret == 0)
  		ret = do_misc_fixups(env);
  
  	/* do 32-bit optimization after insn patching has done so those patched
  	 * insns could be handled correctly.
  	 */
  	if (ret == 0 && !bpf_prog_is_dev_bound(env->prog->aux)) {
  		ret = opt_subreg_zext_lo32_rnd_hi32(env, attr);
  		env->prog->aux->verifier_zext = bpf_jit_needs_zext() ? !ret
  								     : false;
  	}
  
  	if (ret == 0)
  		ret = fixup_call_args(env);
  
  	env->verification_time = ktime_get_ns() - start_time;
  	print_verification_stats(env);
  	env->prog->aux->verified_insns = env->insn_processed;
  
  	if (log->level && bpf_verifier_log_full(log))
  		ret = -ENOSPC;
  	if (log->level && !log->ubuf) {
  		ret = -EFAULT;
  		goto err_release_maps;
  	}
  
  	if (ret)
  		goto err_release_maps;
  
  	if (env->used_map_cnt) {
  		/* if program passed verifier, update used_maps in bpf_prog_info */
  		env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
  							  sizeof(env->used_maps[0]),
  							  GFP_KERNEL);
  
  		if (!env->prog->aux->used_maps) {
  			ret = -ENOMEM;
  			goto err_release_maps;
  		}
  
  		memcpy(env->prog->aux->used_maps, env->used_maps,
  		       sizeof(env->used_maps[0]) * env->used_map_cnt);
  		env->prog->aux->used_map_cnt = env->used_map_cnt;
  	}
  	if (env->used_btf_cnt) {
  		/* if program passed verifier, update used_btfs in bpf_prog_aux */
  		env->prog->aux->used_btfs = kmalloc_array(env->used_btf_cnt,
  							  sizeof(env->used_btfs[0]),
  							  GFP_KERNEL);
  		if (!env->prog->aux->used_btfs) {
  			ret = -ENOMEM;
  			goto err_release_maps;
  		}
  
  		memcpy(env->prog->aux->used_btfs, env->used_btfs,
  		       sizeof(env->used_btfs[0]) * env->used_btf_cnt);
  		env->prog->aux->used_btf_cnt = env->used_btf_cnt;
  	}
  	if (env->used_map_cnt || env->used_btf_cnt) {
  		/* program is valid. Convert pseudo bpf_ld_imm64 into generic
  		 * bpf_ld_imm64 instructions
  		 */
  		convert_pseudo_ld_imm64(env);
  	}
  
  	adjust_btf_func(env);
  
  err_release_maps:
  	if (!env->prog->aux->used_maps)
  		/* if we didn't copy map pointers into bpf_prog_info, release
  		 * them now. Otherwise free_used_maps() will release them.
  		 */
  		release_maps(env);
  	if (!env->prog->aux->used_btfs)
  		release_btfs(env);
  
  	/* extension progs temporarily inherit the attach_type of their targets
  	   for verification purposes, so set it back to zero before returning
  	 */
  	if (env->prog->type == BPF_PROG_TYPE_EXT)
  		env->prog->expected_attach_type = 0;
  
  	*prog = env->prog;
  err_unlock:
  	if (!is_priv)
  		mutex_unlock(&bpf_verifier_lock);
  	vfree(env->insn_aux_data);
  err_free_env:
  	kfree(env);
  	return ret;
  }
  