text: // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
  /* Copyright (c) 2019 Netronome Systems, Inc. */
  
  #include <errno.h>
  #include <fcntl.h>
  #include <string.h>
  #include <stdlib.h>
  #include <unistd.h>
  #include <net/if.h>
  #include <sys/utsname.h>
  
  #include <linux/btf.h>
  #include <linux/filter.h>
  #include <linux/kernel.h>
  
  #include "bpf.h"
  #include "libbpf.h"
  #include "libbpf_internal.h"
  
  static bool grep(const char *buffer, const char *pattern)
  {
  	return !!strstr(buffer, pattern);
  }
  
  static int get_vendor_id(int ifindex)
  {
  	char ifname[IF_NAMESIZE], path[64], buf[8];
  	ssize_t len;
  	int fd;
  
  	if (!if_indextoname(ifindex, ifname))
  		return -1;
  
  	snprintf(path, sizeof(path), "/sys/class/net/%s/device/vendor", ifname);
  
  	fd = open(path, O_RDONLY);
  	if (fd < 0)
  		return -1;
  
  	len = read(fd, buf, sizeof(buf));
  	close(fd);
  	if (len < 0)
  		return -1;
  	if (len >= (ssize_t)sizeof(buf))
  		return -1;
  	buf[len] = '\0';
  
  	return strtol(buf, NULL, 0);
  }
  
  static int get_kernel_version(void)
  {
  	int version, subversion, patchlevel;
  	struct utsname utsn;
  
  	/* Return 0 on failure, and attempt to probe with empty kversion */
  	if (uname(&utsn))
  		return 0;
  
  	if (sscanf(utsn.release, "%d.%d.%d",
  		   &version, &subversion, &patchlevel) != 3)
  		return 0;
  
  	return (version << 16) + (subversion << 8) + patchlevel;
  }
  
  static void
  probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
  	   size_t insns_cnt, char *buf, size_t buf_len, __u32 ifindex)
  {
  	struct bpf_load_program_attr xattr = {};
  	int fd;
  
  	switch (prog_type) {
  	case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
  		xattr.expected_attach_type = BPF_CGROUP_INET4_CONNECT;
  		break;
  	case BPF_PROG_TYPE_CGROUP_SOCKOPT:
  		xattr.expected_attach_type = BPF_CGROUP_GETSOCKOPT;
  		break;
  	case BPF_PROG_TYPE_SK_LOOKUP:
  		xattr.expected_attach_type = BPF_SK_LOOKUP;
  		break;
  	case BPF_PROG_TYPE_KPROBE:
  		xattr.kern_version = get_kernel_version();
  		break;
  	case BPF_PROG_TYPE_UNSPEC:
  	case BPF_PROG_TYPE_SOCKET_FILTER:
  	case BPF_PROG_TYPE_SCHED_CLS:
  	case BPF_PROG_TYPE_SCHED_ACT:
  	case BPF_PROG_TYPE_TRACEPOINT:
  	case BPF_PROG_TYPE_XDP:
  	case BPF_PROG_TYPE_PERF_EVENT:
  	case BPF_PROG_TYPE_CGROUP_SKB:
  	case BPF_PROG_TYPE_CGROUP_SOCK:
  	case BPF_PROG_TYPE_LWT_IN:
  	case BPF_PROG_TYPE_LWT_OUT:
  	case BPF_PROG_TYPE_LWT_XMIT:
  	case BPF_PROG_TYPE_SOCK_OPS:
  	case BPF_PROG_TYPE_SK_SKB:
  	case BPF_PROG_TYPE_CGROUP_DEVICE:
  	case BPF_PROG_TYPE_SK_MSG:
  	case BPF_PROG_TYPE_RAW_TRACEPOINT:
  	case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
  	case BPF_PROG_TYPE_LWT_SEG6LOCAL:
  	case BPF_PROG_TYPE_LIRC_MODE2:
  	case BPF_PROG_TYPE_SK_REUSEPORT:
  	case BPF_PROG_TYPE_FLOW_DISSECTOR:
  	case BPF_PROG_TYPE_CGROUP_SYSCTL:
  	case BPF_PROG_TYPE_TRACING:
  	case BPF_PROG_TYPE_STRUCT_OPS:
  	case BPF_PROG_TYPE_EXT:
  	case BPF_PROG_TYPE_LSM:
  	default:
  		break;
  	}
  
  	xattr.prog_type = prog_type;
  	xattr.insns = insns;
  	xattr.insns_cnt = insns_cnt;
  	xattr.license = "GPL";
  	xattr.prog_ifindex = ifindex;
  
  	fd = bpf_load_program_xattr(&xattr, buf, buf_len);
  	if (fd >= 0)
  		close(fd);
  }
  
  bool bpf_probe_prog_type(enum bpf_prog_type prog_type, __u32 ifindex)
  {
  	struct bpf_insn insns[2] = {
  		BPF_MOV64_IMM(BPF_REG_0, 0),
  		BPF_EXIT_INSN()
  	};
  
  	if (ifindex && prog_type == BPF_PROG_TYPE_SCHED_CLS)
  		/* nfp returns -EINVAL on exit(0) with TC offload */
  		insns[0].imm = 2;
  
  	errno = 0;
  	probe_load(prog_type, insns, ARRAY_SIZE(insns), NULL, 0, ifindex);
  
  	return errno != EINVAL && errno != EOPNOTSUPP;
  }
  
  int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
  			 const char *str_sec, size_t str_len)
  {
  	struct btf_header hdr = {
  		.magic = BTF_MAGIC,
  		.version = BTF_VERSION,
  		.hdr_len = sizeof(struct btf_header),
  		.type_len = types_len,
  		.str_off = types_len,
  		.str_len = str_len,
  	};
  	int btf_fd, btf_len;
  	__u8 *raw_btf;
  
  	btf_len = hdr.hdr_len + hdr.type_len + hdr.str_len;
  	raw_btf = malloc(btf_len);
  	if (!raw_btf)
  		return -ENOMEM;
  
  	memcpy(raw_btf, &hdr, sizeof(hdr));
  	memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len);
  	memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len);
  
  	btf_fd = bpf_load_btf(raw_btf, btf_len, NULL, 0, false);
  
  	free(raw_btf);
  	return btf_fd;
  }
  
  static int load_local_storage_btf(void)
  {
  	const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l";
  	/* struct bpf_spin_lock {
  	 *   int val;
  	 * };
  	 * struct val {
  	 *   int cnt;
  	 *   struct bpf_spin_lock l;
  	 * };
  	 */
  	__u32 types[] = {
  		/* int */
  		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
  		/* struct bpf_spin_lock */                      /* [2] */
  		BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 4),
  		BTF_MEMBER_ENC(15, 1, 0), /* int val; */
  		/* struct val */                                /* [3] */
  		BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
  		BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
  		BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
  	};
  
  	return libbpf__load_raw_btf((char *)types, sizeof(types),
  				     strs, sizeof(strs));
  }
  
  bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
  {
  	int key_size, value_size, max_entries, map_flags;
  	__u32 btf_key_type_id = 0, btf_value_type_id = 0;
  	struct bpf_create_map_attr attr = {};
  	int fd = -1, btf_fd = -1, fd_inner;
  
  	key_size	= sizeof(__u32);
  	value_size	= sizeof(__u32);
  	max_entries	= 1;
  	map_flags	= 0;
  
  	switch (map_type) {
  	case BPF_MAP_TYPE_STACK_TRACE:
  		value_size	= sizeof(__u64);
  		break;
  	case BPF_MAP_TYPE_LPM_TRIE:
  		key_size	= sizeof(__u64);
  		value_size	= sizeof(__u64);
  		map_flags	= BPF_F_NO_PREALLOC;
  		break;
  	case BPF_MAP_TYPE_CGROUP_STORAGE:
  	case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
  		key_size	= sizeof(struct bpf_cgroup_storage_key);
  		value_size	= sizeof(__u64);
  		max_entries	= 0;
  		break;
  	case BPF_MAP_TYPE_QUEUE:
  	case BPF_MAP_TYPE_STACK:
  		key_size	= 0;
  		break;
  	case BPF_MAP_TYPE_SK_STORAGE:
  	case BPF_MAP_TYPE_INODE_STORAGE:
  	case BPF_MAP_TYPE_TASK_STORAGE:
  		btf_key_type_id = 1;
  		btf_value_type_id = 3;
  		value_size = 8;
  		max_entries = 0;
  		map_flags = BPF_F_NO_PREALLOC;
  		btf_fd = load_local_storage_btf();
  		if (btf_fd < 0)
  			return false;
  		break;
  	case BPF_MAP_TYPE_RINGBUF:
  		key_size = 0;
  		value_size = 0;
  		max_entries = 4096;
  		break;
  	case BPF_MAP_TYPE_UNSPEC:
  	case BPF_MAP_TYPE_HASH:
  	case BPF_MAP_TYPE_ARRAY:
  	case BPF_MAP_TYPE_PROG_ARRAY:
  	case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
  	case BPF_MAP_TYPE_PERCPU_HASH:
  	case BPF_MAP_TYPE_PERCPU_ARRAY:
  	case BPF_MAP_TYPE_CGROUP_ARRAY:
  	case BPF_MAP_TYPE_LRU_HASH:
  	case BPF_MAP_TYPE_LRU_PERCPU_HASH:
  	case BPF_MAP_TYPE_ARRAY_OF_MAPS:
  	case BPF_MAP_TYPE_HASH_OF_MAPS:
  	case BPF_MAP_TYPE_DEVMAP:
  	case BPF_MAP_TYPE_DEVMAP_HASH:
  	case BPF_MAP_TYPE_SOCKMAP:
  	case BPF_MAP_TYPE_CPUMAP:
  	case BPF_MAP_TYPE_XSKMAP:
  	case BPF_MAP_TYPE_SOCKHASH:
  	case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
  	case BPF_MAP_TYPE_STRUCT_OPS:
  	default:
  		break;
  	}
  
  	if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
  	    map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
  		/* TODO: probe for device, once libbpf has a function to create
  		 * map-in-map for offload
  		 */
  		if (ifindex)
  			return false;
  
  		fd_inner = bpf_create_map(BPF_MAP_TYPE_HASH,
  					  sizeof(__u32), sizeof(__u32), 1, 0);
  		if (fd_inner < 0)
  			return false;
  		fd = bpf_create_map_in_map(map_type, NULL, sizeof(__u32),
  					   fd_inner, 1, 0);
  		close(fd_inner);
  	} else {
  		/* Note: No other restriction on map type probes for offload */
  		attr.map_type = map_type;
  		attr.key_size = key_size;
  		attr.value_size = value_size;
  		attr.max_entries = max_entries;
  		attr.map_flags = map_flags;
  		attr.map_ifindex = ifindex;
  		if (btf_fd >= 0) {
  			attr.btf_fd = btf_fd;
  			attr.btf_key_type_id = btf_key_type_id;
  			attr.btf_value_type_id = btf_value_type_id;
  		}
  
  		fd = bpf_create_map_xattr(&attr);
  	}
  	if (fd >= 0)
  		close(fd);
  	if (btf_fd >= 0)
  		close(btf_fd);
  
  	return fd >= 0;
  }
  
  bool bpf_probe_helper(enum bpf_func_id id, enum bpf_prog_type prog_type,
  		      __u32 ifindex)
  {
  	struct bpf_insn insns[2] = {
  		BPF_EMIT_CALL(id),
  		BPF_EXIT_INSN()
  	};
  	char buf[4096] = {};
  	bool res;
  
  	probe_load(prog_type, insns, ARRAY_SIZE(insns), buf, sizeof(buf),
  		   ifindex);
  	res = !grep(buf, "invalid func ") && !grep(buf, "unknown func ");
  
  	if (ifindex) {
  		switch (get_vendor_id(ifindex)) {
  		case 0x19ee: /* Netronome specific */
  			res = res && !grep(buf, "not supported by FW") &&
  				!grep(buf, "unsupported function id");
  			break;
  		default:
  			break;
  		}
  	}
  
  	return res;
  }
  
  /*
   * Probe for availability of kernel commit (5.3):
   *
   * c04c0d2b968a ("bpf: increase complexity limit and maximum program size")
   */
  bool bpf_probe_large_insn_limit(__u32 ifindex)
  {
  	struct bpf_insn insns[BPF_MAXINSNS + 1];
  	int i;
  
  	for (i = 0; i < BPF_MAXINSNS; i++)
  		insns[i] = BPF_MOV64_IMM(BPF_REG_0, 1);
  	insns[BPF_MAXINSNS] = BPF_EXIT_INSN();
  
  	errno = 0;
  	probe_load(BPF_PROG_TYPE_SCHED_CLS, insns, ARRAY_SIZE(insns), NULL, 0,
  		   ifindex);
  
  	return errno != E2BIG && errno != EINVAL;
  }
  