text: // SPDX-License-Identifier: GPL-2.0
  // Copyright (c) 2019 Facebook
  
  #include <fcntl.h>
  #include <stdint.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  
  #include <linux/filter.h>
  
  #include <bpf/bpf.h>
  #include <bpf/libbpf.h>
  
  #include <bpf/bpf_endian.h>
  #include "bpf_rlimit.h"
  #include "bpf_util.h"
  #include "cgroup_helpers.h"
  
  #define CG_PATH			"/foo"
  #define MAX_INSNS		512
  #define FIXUP_SYSCTL_VALUE	0
  
  char bpf_log_buf[BPF_LOG_BUF_SIZE];
  
  struct sysctl_test {
  	const char *descr;
  	size_t fixup_value_insn;
  	struct bpf_insn	insns[MAX_INSNS];
  	const char *prog_file;
  	enum bpf_attach_type attach_type;
  	const char *sysctl;
  	int open_flags;
  	int seek;
  	const char *newval;
  	const char *oldval;
  	enum {
  		LOAD_REJECT,
  		ATTACH_REJECT,
  		OP_EPERM,
  		SUCCESS,
  	} result;
  };
  
  static struct sysctl_test tests[] = {
  	{
  		.descr = "sysctl wrong attach_type",
  		.insns = {
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = 0,
  		.sysctl = "kernel/ostype",
  		.open_flags = O_RDONLY,
  		.result = ATTACH_REJECT,
  	},
  	{
  		.descr = "sysctl:read allow all",
  		.insns = {
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "kernel/ostype",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		.descr = "sysctl:read deny all",
  		.insns = {
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "kernel/ostype",
  		.open_flags = O_RDONLY,
  		.result = OP_EPERM,
  	},
  	{
  		.descr = "ctx:write sysctl:read read ok",
  		.insns = {
  			/* If (write) */
  			BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_1,
  				    offsetof(struct bpf_sysctl, write)),
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 1, 2),
  
  			/* return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_JMP_A(1),
  
  			/* else return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "kernel/ostype",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		.descr = "ctx:write sysctl:write read ok",
  		.insns = {
  			/* If (write) */
  			BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_1,
  				    offsetof(struct bpf_sysctl, write)),
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 1, 2),
  
  			/* return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_JMP_A(1),
  
  			/* else return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "kernel/domainname",
  		.open_flags = O_WRONLY,
  		.newval = "(none)", /* same as default, should fail anyway */
  		.result = OP_EPERM,
  	},
  	{
  		.descr = "ctx:write sysctl:write read ok narrow",
  		.insns = {
  			/* u64 w = (u16)write & 1; */
  #if __BYTE_ORDER == __LITTLE_ENDIAN
  			BPF_LDX_MEM(BPF_H, BPF_REG_7, BPF_REG_1,
  				    offsetof(struct bpf_sysctl, write)),
  #else
  			BPF_LDX_MEM(BPF_H, BPF_REG_7, BPF_REG_1,
  				    offsetof(struct bpf_sysctl, write) + 2),
  #endif
  			BPF_ALU64_IMM(BPF_AND, BPF_REG_7, 1),
  			/* return 1 - w; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_7),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "kernel/domainname",
  		.open_flags = O_WRONLY,
  		.newval = "(none)", /* same as default, should fail anyway */
  		.result = OP_EPERM,
  	},
  	{
  		.descr = "ctx:write sysctl:read write reject",
  		.insns = {
  			/* write = X */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
  				    offsetof(struct bpf_sysctl, write)),
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "kernel/ostype",
  		.open_flags = O_RDONLY,
  		.result = LOAD_REJECT,
  	},
  	{
  		.descr = "ctx:file_pos sysctl:read read ok",
  		.insns = {
  			/* If (file_pos == X) */
  			BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_1,
  				    offsetof(struct bpf_sysctl, file_pos)),
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 3, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "kernel/ostype",
  		.open_flags = O_RDONLY,
  		.seek = 3,
  		.result = SUCCESS,
  	},
  	{
  		.descr = "ctx:file_pos sysctl:read read ok narrow",
  		.insns = {
  			/* If (file_pos == X) */
  #if __BYTE_ORDER == __LITTLE_ENDIAN
  			BPF_LDX_MEM(BPF_B, BPF_REG_7, BPF_REG_1,
  				    offsetof(struct bpf_sysctl, file_pos)),
  #else
  			BPF_LDX_MEM(BPF_B, BPF_REG_7, BPF_REG_1,
  				    offsetof(struct bpf_sysctl, file_pos) + 3),
  #endif
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 4, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "kernel/ostype",
  		.open_flags = O_RDONLY,
  		.seek = 4,
  		.result = SUCCESS,
  	},
  	{
  		.descr = "ctx:file_pos sysctl:read write ok",
  		.insns = {
  			/* file_pos = X */
  			BPF_MOV64_IMM(BPF_REG_0, 2),
  			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
  				    offsetof(struct bpf_sysctl, file_pos)),
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "kernel/ostype",
  		.open_flags = O_RDONLY,
  		.oldval = "nux\n",
  		.result = SUCCESS,
  	},
  	{
  		.descr = "sysctl_get_name sysctl_value:base ok",
  		.insns = {
  			/* sysctl_get_name arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_get_name arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 8),
  
  			/* sysctl_get_name arg4 (flags) */
  			BPF_MOV64_IMM(BPF_REG_4, BPF_F_SYSCTL_BASE_NAME),
  
  			/* sysctl_get_name(ctx, buf, buf_len, flags) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, sizeof("tcp_mem") - 1, 6),
  			/*     buf == "tcp_mem\0") */
  			BPF_LD_IMM64(BPF_REG_8,
  				     bpf_be64_to_cpu(0x7463705f6d656d00ULL)),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/tcp_mem",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		.descr = "sysctl_get_name sysctl_value:base E2BIG truncated",
  		.insns = {
  			/* sysctl_get_name arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_get_name arg3 (buf_len) too small */
  			BPF_MOV64_IMM(BPF_REG_3, 7),
  
  			/* sysctl_get_name arg4 (flags) */
  			BPF_MOV64_IMM(BPF_REG_4, BPF_F_SYSCTL_BASE_NAME),
  
  			/* sysctl_get_name(ctx, buf, buf_len, flags) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 6),
  
  			/*     buf[0:7] == "tcp_me\0") */
  			BPF_LD_IMM64(BPF_REG_8,
  				     bpf_be64_to_cpu(0x7463705f6d650000ULL)),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/tcp_mem",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		.descr = "sysctl_get_name sysctl:full ok",
  		.insns = {
  			/* sysctl_get_name arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -24),
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 8),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 16),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_get_name arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 17),
  
  			/* sysctl_get_name arg4 (flags) */
  			BPF_MOV64_IMM(BPF_REG_4, 0),
  
  			/* sysctl_get_name(ctx, buf, buf_len, flags) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 16, 14),
  
  			/*     buf[0:8] == "net/ipv4" && */
  			BPF_LD_IMM64(BPF_REG_8,
  				     bpf_be64_to_cpu(0x6e65742f69707634ULL)),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 10),
  
  			/*     buf[8:16] == "/tcp_mem" && */
  			BPF_LD_IMM64(BPF_REG_8,
  				     bpf_be64_to_cpu(0x2f7463705f6d656dULL)),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 8),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 6),
  
  			/*     buf[16:24] == "\0") */
  			BPF_LD_IMM64(BPF_REG_8, 0x0ULL),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 16),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/tcp_mem",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		.descr = "sysctl_get_name sysctl:full E2BIG truncated",
  		.insns = {
  			/* sysctl_get_name arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -16),
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 8),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_get_name arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 16),
  
  			/* sysctl_get_name arg4 (flags) */
  			BPF_MOV64_IMM(BPF_REG_4, 0),
  
  			/* sysctl_get_name(ctx, buf, buf_len, flags) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 10),
  
  			/*     buf[0:8] == "net/ipv4" && */
  			BPF_LD_IMM64(BPF_REG_8,
  				     bpf_be64_to_cpu(0x6e65742f69707634ULL)),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 6),
  
  			/*     buf[8:16] == "/tcp_me\0") */
  			BPF_LD_IMM64(BPF_REG_8,
  				     bpf_be64_to_cpu(0x2f7463705f6d6500ULL)),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 8),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/tcp_mem",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		.descr = "sysctl_get_name sysctl:full E2BIG truncated small",
  		.insns = {
  			/* sysctl_get_name arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_get_name arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 7),
  
  			/* sysctl_get_name arg4 (flags) */
  			BPF_MOV64_IMM(BPF_REG_4, 0),
  
  			/* sysctl_get_name(ctx, buf, buf_len, flags) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 6),
  
  			/*     buf[0:8] == "net/ip\0") */
  			BPF_LD_IMM64(BPF_REG_8,
  				     bpf_be64_to_cpu(0x6e65742f69700000ULL)),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/tcp_mem",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		.descr = "sysctl_get_current_value sysctl:read ok, gt",
  		.insns = {
  			/* sysctl_get_current_value arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_get_current_value arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 8),
  
  			/* sysctl_get_current_value(ctx, buf, buf_len) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 6, 6),
  
  			/*     buf[0:6] == "Linux\n\0") */
  			BPF_LD_IMM64(BPF_REG_8,
  				     bpf_be64_to_cpu(0x4c696e75780a0000ULL)),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "kernel/ostype",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		.descr = "sysctl_get_current_value sysctl:read ok, eq",
  		.insns = {
  			/* sysctl_get_current_value arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_STX_MEM(BPF_B, BPF_REG_7, BPF_REG_0, 7),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_get_current_value arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 7),
  
  			/* sysctl_get_current_value(ctx, buf, buf_len) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 6, 6),
  
  			/*     buf[0:6] == "Linux\n\0") */
  			BPF_LD_IMM64(BPF_REG_8,
  				     bpf_be64_to_cpu(0x4c696e75780a0000ULL)),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "kernel/ostype",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		.descr = "sysctl_get_current_value sysctl:read E2BIG truncated",
  		.insns = {
  			/* sysctl_get_current_value arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_STX_MEM(BPF_H, BPF_REG_7, BPF_REG_0, 6),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_get_current_value arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 6),
  
  			/* sysctl_get_current_value(ctx, buf, buf_len) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 6),
  
  			/*     buf[0:6] == "Linux\0") */
  			BPF_LD_IMM64(BPF_REG_8,
  				     bpf_be64_to_cpu(0x4c696e7578000000ULL)),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "kernel/ostype",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		.descr = "sysctl_get_current_value sysctl:read EINVAL",
  		.insns = {
  			/* sysctl_get_current_value arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_get_current_value arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 8),
  
  			/* sysctl_get_current_value(ctx, buf, buf_len) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -EINVAL, 4),
  
  			/*     buf[0:8] is NUL-filled) */
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 0, 2),
  
  			/* return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_JMP_A(1),
  
  			/* else return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv6/conf/lo/stable_secret", /* -EIO */
  		.open_flags = O_RDONLY,
  		.result = OP_EPERM,
  	},
  	{
  		.descr = "sysctl_get_current_value sysctl:write ok",
  		.fixup_value_insn = 6,
  		.insns = {
  			/* sysctl_get_current_value arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_get_current_value arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 8),
  
  			/* sysctl_get_current_value(ctx, buf, buf_len) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 4, 6),
  
  			/*     buf[0:4] == expected) */
  			BPF_LD_IMM64(BPF_REG_8, FIXUP_SYSCTL_VALUE),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
  
  			/* return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_JMP_A(1),
  
  			/* else return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_WRONLY,
  		.newval = "600", /* same as default, should fail anyway */
  		.result = OP_EPERM,
  	},
  	{
  		.descr = "sysctl_get_new_value sysctl:read EINVAL",
  		.insns = {
  			/* sysctl_get_new_value arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_get_new_value arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 8),
  
  			/* sysctl_get_new_value(ctx, buf, buf_len) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_get_new_value),
  
  			/* if (ret == expected) */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -EINVAL, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/tcp_mem",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		.descr = "sysctl_get_new_value sysctl:write ok",
  		.insns = {
  			/* sysctl_get_new_value arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_get_new_value arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 4),
  
  			/* sysctl_get_new_value(ctx, buf, buf_len) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_get_new_value),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 3, 4),
  
  			/*     buf[0:4] == "606\0") */
  			BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_9,
  				    bpf_ntohl(0x36303600), 2),
  
  			/* return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_JMP_A(1),
  
  			/* else return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_WRONLY,
  		.newval = "606",
  		.result = OP_EPERM,
  	},
  	{
  		.descr = "sysctl_get_new_value sysctl:write ok long",
  		.insns = {
  			/* sysctl_get_new_value arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -24),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_get_new_value arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 24),
  
  			/* sysctl_get_new_value(ctx, buf, buf_len) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_get_new_value),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 23, 14),
  
  			/*     buf[0:8] == "3000000 " && */
  			BPF_LD_IMM64(BPF_REG_8,
  				     bpf_be64_to_cpu(0x3330303030303020ULL)),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 10),
  
  			/*     buf[8:16] == "4000000 " && */
  			BPF_LD_IMM64(BPF_REG_8,
  				     bpf_be64_to_cpu(0x3430303030303020ULL)),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 8),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 6),
  
  			/*     buf[16:24] == "6000000\0") */
  			BPF_LD_IMM64(BPF_REG_8,
  				     bpf_be64_to_cpu(0x3630303030303000ULL)),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 16),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
  
  			/* return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_JMP_A(1),
  
  			/* else return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/tcp_mem",
  		.open_flags = O_WRONLY,
  		.newval = "3000000 4000000 6000000",
  		.result = OP_EPERM,
  	},
  	{
  		.descr = "sysctl_get_new_value sysctl:write E2BIG",
  		.insns = {
  			/* sysctl_get_new_value arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_STX_MEM(BPF_B, BPF_REG_7, BPF_REG_0, 3),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_get_new_value arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 3),
  
  			/* sysctl_get_new_value(ctx, buf, buf_len) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_get_new_value),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 4),
  
  			/*     buf[0:3] == "60\0") */
  			BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_9,
  				    bpf_ntohl(0x36300000), 2),
  
  			/* return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_JMP_A(1),
  
  			/* else return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_WRONLY,
  		.newval = "606",
  		.result = OP_EPERM,
  	},
  	{
  		.descr = "sysctl_set_new_value sysctl:read EINVAL",
  		.insns = {
  			/* sysctl_set_new_value arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_MOV64_IMM(BPF_REG_0,
  				      bpf_ntohl(0x36303000)),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_set_new_value arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 3),
  
  			/* sysctl_set_new_value(ctx, buf, buf_len) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_set_new_value),
  
  			/* if (ret == expected) */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -EINVAL, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		.descr = "sysctl_set_new_value sysctl:write ok",
  		.fixup_value_insn = 2,
  		.insns = {
  			/* sysctl_set_new_value arg2 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_LD_IMM64(BPF_REG_0, FIXUP_SYSCTL_VALUE),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  
  			BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
  
  			/* sysctl_set_new_value arg3 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_3, 3),
  
  			/* sysctl_set_new_value(ctx, buf, buf_len) */
  			BPF_EMIT_CALL(BPF_FUNC_sysctl_set_new_value),
  
  			/* if (ret == expected) */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_WRONLY,
  		.newval = "606",
  		.result = SUCCESS,
  	},
  	{
  		"bpf_strtoul one number string",
  		.insns = {
  			/* arg1 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_MOV64_IMM(BPF_REG_0,
  				      bpf_ntohl(0x36303000)),
  			BPF_STX_MEM(BPF_W, BPF_REG_7, BPF_REG_0, 0),
  
  			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
  
  			/* arg2 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_2, 4),
  
  			/* arg3 (flags) */
  			BPF_MOV64_IMM(BPF_REG_3, 0),
  
  			/* arg4 (res) */
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_MOV64_REG(BPF_REG_4, BPF_REG_7),
  
  			BPF_EMIT_CALL(BPF_FUNC_strtoul),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 3, 4),
  			/*     res == expected) */
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 600, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		"bpf_strtoul multi number string",
  		.insns = {
  			/* arg1 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			/* "600 602\0" */
  			BPF_LD_IMM64(BPF_REG_0,
  				     bpf_be64_to_cpu(0x3630302036303200ULL)),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
  
  			/* arg2 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_2, 8),
  
  			/* arg3 (flags) */
  			BPF_MOV64_IMM(BPF_REG_3, 0),
  
  			/* arg4 (res) */
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_MOV64_REG(BPF_REG_4, BPF_REG_7),
  
  			BPF_EMIT_CALL(BPF_FUNC_strtoul),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 3, 18),
  			/*     res == expected) */
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 600, 16),
  
  			/*     arg1 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_ALU64_REG(BPF_ADD, BPF_REG_7, BPF_REG_0),
  			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
  
  			/*     arg2 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_2, 8),
  			BPF_ALU64_REG(BPF_SUB, BPF_REG_2, BPF_REG_0),
  
  			/*     arg3 (flags) */
  			BPF_MOV64_IMM(BPF_REG_3, 0),
  
  			/*     arg4 (res) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -16),
  			BPF_MOV64_REG(BPF_REG_4, BPF_REG_7),
  
  			BPF_EMIT_CALL(BPF_FUNC_strtoul),
  
  			/*     if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 4, 4),
  			/*         res == expected) */
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 602, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/tcp_mem",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		"bpf_strtoul buf_len = 0, reject",
  		.insns = {
  			/* arg1 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_MOV64_IMM(BPF_REG_0,
  				      bpf_ntohl(0x36303000)),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  
  			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
  
  			/* arg2 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_2, 0),
  
  			/* arg3 (flags) */
  			BPF_MOV64_IMM(BPF_REG_3, 0),
  
  			/* arg4 (res) */
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_MOV64_REG(BPF_REG_4, BPF_REG_7),
  
  			BPF_EMIT_CALL(BPF_FUNC_strtoul),
  
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_RDONLY,
  		.result = LOAD_REJECT,
  	},
  	{
  		"bpf_strtoul supported base, ok",
  		.insns = {
  			/* arg1 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_MOV64_IMM(BPF_REG_0,
  				      bpf_ntohl(0x30373700)),
  			BPF_STX_MEM(BPF_W, BPF_REG_7, BPF_REG_0, 0),
  
  			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
  
  			/* arg2 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_2, 4),
  
  			/* arg3 (flags) */
  			BPF_MOV64_IMM(BPF_REG_3, 8),
  
  			/* arg4 (res) */
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_MOV64_REG(BPF_REG_4, BPF_REG_7),
  
  			BPF_EMIT_CALL(BPF_FUNC_strtoul),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 3, 4),
  			/*     res == expected) */
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 63, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		"bpf_strtoul unsupported base, EINVAL",
  		.insns = {
  			/* arg1 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_MOV64_IMM(BPF_REG_0,
  				      bpf_ntohl(0x36303000)),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  
  			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
  
  			/* arg2 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_2, 4),
  
  			/* arg3 (flags) */
  			BPF_MOV64_IMM(BPF_REG_3, 3),
  
  			/* arg4 (res) */
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_MOV64_REG(BPF_REG_4, BPF_REG_7),
  
  			BPF_EMIT_CALL(BPF_FUNC_strtoul),
  
  			/* if (ret == expected) */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -EINVAL, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		"bpf_strtoul buf with spaces only, EINVAL",
  		.insns = {
  			/* arg1 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_MOV64_IMM(BPF_REG_0,
  				      bpf_ntohl(0x0d0c0a09)),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  
  			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
  
  			/* arg2 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_2, 4),
  
  			/* arg3 (flags) */
  			BPF_MOV64_IMM(BPF_REG_3, 0),
  
  			/* arg4 (res) */
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_MOV64_REG(BPF_REG_4, BPF_REG_7),
  
  			BPF_EMIT_CALL(BPF_FUNC_strtoul),
  
  			/* if (ret == expected) */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -EINVAL, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		"bpf_strtoul negative number, EINVAL",
  		.insns = {
  			/* arg1 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			/* " -6\0" */
  			BPF_MOV64_IMM(BPF_REG_0,
  				      bpf_ntohl(0x0a2d3600)),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  
  			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
  
  			/* arg2 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_2, 4),
  
  			/* arg3 (flags) */
  			BPF_MOV64_IMM(BPF_REG_3, 0),
  
  			/* arg4 (res) */
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_MOV64_REG(BPF_REG_4, BPF_REG_7),
  
  			BPF_EMIT_CALL(BPF_FUNC_strtoul),
  
  			/* if (ret == expected) */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -EINVAL, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		"bpf_strtol negative number, ok",
  		.insns = {
  			/* arg1 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			/* " -6\0" */
  			BPF_MOV64_IMM(BPF_REG_0,
  				      bpf_ntohl(0x0a2d3600)),
  			BPF_STX_MEM(BPF_W, BPF_REG_7, BPF_REG_0, 0),
  
  			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
  
  			/* arg2 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_2, 4),
  
  			/* arg3 (flags) */
  			BPF_MOV64_IMM(BPF_REG_3, 10),
  
  			/* arg4 (res) */
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_MOV64_REG(BPF_REG_4, BPF_REG_7),
  
  			BPF_EMIT_CALL(BPF_FUNC_strtol),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 3, 4),
  			/*     res == expected) */
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_9, -6, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		"bpf_strtol hex number, ok",
  		.insns = {
  			/* arg1 (buf) */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			/* "0xfe" */
  			BPF_MOV64_IMM(BPF_REG_0,
  				      bpf_ntohl(0x30786665)),
  			BPF_STX_MEM(BPF_W, BPF_REG_7, BPF_REG_0, 0),
  
  			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
  
  			/* arg2 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_2, 4),
  
  			/* arg3 (flags) */
  			BPF_MOV64_IMM(BPF_REG_3, 0),
  
  			/* arg4 (res) */
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_MOV64_REG(BPF_REG_4, BPF_REG_7),
  
  			BPF_EMIT_CALL(BPF_FUNC_strtol),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 4, 4),
  			/*     res == expected) */
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 254, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		"bpf_strtol max long",
  		.insns = {
  			/* arg1 (buf) 9223372036854775807 */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -24),
  			BPF_LD_IMM64(BPF_REG_0,
  				     bpf_be64_to_cpu(0x3932323333373230ULL)),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_LD_IMM64(BPF_REG_0,
  				     bpf_be64_to_cpu(0x3336383534373735ULL)),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 8),
  			BPF_LD_IMM64(BPF_REG_0,
  				     bpf_be64_to_cpu(0x3830370000000000ULL)),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 16),
  
  			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
  
  			/* arg2 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_2, 19),
  
  			/* arg3 (flags) */
  			BPF_MOV64_IMM(BPF_REG_3, 0),
  
  			/* arg4 (res) */
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_MOV64_REG(BPF_REG_4, BPF_REG_7),
  
  			BPF_EMIT_CALL(BPF_FUNC_strtol),
  
  			/* if (ret == expected && */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 19, 6),
  			/*     res == expected) */
  			BPF_LD_IMM64(BPF_REG_8, 0x7fffffffffffffffULL),
  			BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
  			BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		"bpf_strtol overflow, ERANGE",
  		.insns = {
  			/* arg1 (buf) 9223372036854775808 */
  			BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -24),
  			BPF_LD_IMM64(BPF_REG_0,
  				     bpf_be64_to_cpu(0x3932323333373230ULL)),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_LD_IMM64(BPF_REG_0,
  				     bpf_be64_to_cpu(0x3336383534373735ULL)),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 8),
  			BPF_LD_IMM64(BPF_REG_0,
  				     bpf_be64_to_cpu(0x3830380000000000ULL)),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 16),
  
  			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
  
  			/* arg2 (buf_len) */
  			BPF_MOV64_IMM(BPF_REG_2, 19),
  
  			/* arg3 (flags) */
  			BPF_MOV64_IMM(BPF_REG_3, 0),
  
  			/* arg4 (res) */
  			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  			BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
  			BPF_MOV64_REG(BPF_REG_4, BPF_REG_7),
  
  			BPF_EMIT_CALL(BPF_FUNC_strtol),
  
  			/* if (ret == expected) */
  			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -ERANGE, 2),
  
  			/* return ALLOW; */
  			BPF_MOV64_IMM(BPF_REG_0, 1),
  			BPF_JMP_A(1),
  
  			/* else return DENY; */
  			BPF_MOV64_IMM(BPF_REG_0, 0),
  			BPF_EXIT_INSN(),
  		},
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  	{
  		"C prog: deny all writes",
  		.prog_file = "./test_sysctl_prog.o",
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/tcp_mem",
  		.open_flags = O_WRONLY,
  		.newval = "123 456 789",
  		.result = OP_EPERM,
  	},
  	{
  		"C prog: deny access by name",
  		.prog_file = "./test_sysctl_prog.o",
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/route/mtu_expires",
  		.open_flags = O_RDONLY,
  		.result = OP_EPERM,
  	},
  	{
  		"C prog: read tcp_mem",
  		.prog_file = "./test_sysctl_prog.o",
  		.attach_type = BPF_CGROUP_SYSCTL,
  		.sysctl = "net/ipv4/tcp_mem",
  		.open_flags = O_RDONLY,
  		.result = SUCCESS,
  	},
  };
  
  static size_t probe_prog_length(const struct bpf_insn *fp)
  {
  	size_t len;
  
  	for (len = MAX_INSNS - 1; len > 0; --len)
  		if (fp[len].code != 0 || fp[len].imm != 0)
  			break;
  	return len + 1;
  }
  
  static int fixup_sysctl_value(const char *buf, size_t buf_len,
  			      struct bpf_insn *prog, size_t insn_num)
  {
  	union {
  		uint8_t raw[sizeof(uint64_t)];
  		uint64_t num;
  	} value = {};
  
  	if (buf_len > sizeof(value)) {
  		log_err("Value is too big (%zd) to use in fixup", buf_len);
  		return -1;
  	}
  	if (prog[insn_num].code != (BPF_LD | BPF_DW | BPF_IMM)) {
  		log_err("Can fixup only BPF_LD_IMM64 insns");
  		return -1;
  	}
  
  	memcpy(value.raw, buf, buf_len);
  	prog[insn_num].imm = (uint32_t)value.num;
  	prog[insn_num + 1].imm = (uint32_t)(value.num >> 32);
  
  	return 0;
  }
  
  static int load_sysctl_prog_insns(struct sysctl_test *test,
  				  const char *sysctl_path)
  {
  	struct bpf_insn *prog = test->insns;
  	struct bpf_load_program_attr attr;
  	int ret;
  
  	memset(&attr, 0, sizeof(struct bpf_load_program_attr));
  	attr.prog_type = BPF_PROG_TYPE_CGROUP_SYSCTL;
  	attr.insns = prog;
  	attr.insns_cnt = probe_prog_length(attr.insns);
  	attr.license = "GPL";
  
  	if (test->fixup_value_insn) {
  		char buf[128];
  		ssize_t len;
  		int fd;
  
  		fd = open(sysctl_path, O_RDONLY | O_CLOEXEC);
  		if (fd < 0) {
  			log_err("open(%s) failed", sysctl_path);
  			return -1;
  		}
  		len = read(fd, buf, sizeof(buf));
  		if (len == -1) {
  			log_err("read(%s) failed", sysctl_path);
  			close(fd);
  			return -1;
  		}
  		close(fd);
  		if (fixup_sysctl_value(buf, len, prog, test->fixup_value_insn))
  			return -1;
  	}
  
  	ret = bpf_load_program_xattr(&attr, bpf_log_buf, BPF_LOG_BUF_SIZE);
  	if (ret < 0 && test->result != LOAD_REJECT) {
  		log_err(">>> Loading program error.\n"
  			">>> Verifier output:\n%s\n-------\n", bpf_log_buf);
  	}
  
  	return ret;
  }
  
  static int load_sysctl_prog_file(struct sysctl_test *test)
  {
  	struct bpf_prog_load_attr attr;
  	struct bpf_object *obj;
  	int prog_fd;
  
  	memset(&attr, 0, sizeof(struct bpf_prog_load_attr));
  	attr.file = test->prog_file;
  	attr.prog_type = BPF_PROG_TYPE_CGROUP_SYSCTL;
  
  	if (bpf_prog_load_xattr(&attr, &obj, &prog_fd)) {
  		if (test->result != LOAD_REJECT)
  			log_err(">>> Loading program (%s) error.\n",
  				test->prog_file);
  		return -1;
  	}
  
  	return prog_fd;
  }
  
  static int load_sysctl_prog(struct sysctl_test *test, const char *sysctl_path)
  {
  		return test->prog_file
  			? load_sysctl_prog_file(test)
  			: load_sysctl_prog_insns(test, sysctl_path);
  }
  
  static int access_sysctl(const char *sysctl_path,
  			 const struct sysctl_test *test)
  {
  	int err = 0;
  	int fd;
  
  	fd = open(sysctl_path, test->open_flags | O_CLOEXEC);
  	if (fd < 0)
  		return fd;
  
  	if (test->seek && lseek(fd, test->seek, SEEK_SET) == -1) {
  		log_err("lseek(%d) failed", test->seek);
  		goto err;
  	}
  
  	if (test->open_flags == O_RDONLY) {
  		char buf[128];
  
  		if (read(fd, buf, sizeof(buf)) == -1)
  			goto err;
  		if (test->oldval &&
  		    strncmp(buf, test->oldval, strlen(test->oldval))) {
  			log_err("Read value %s != %s", buf, test->oldval);
  			goto err;
  		}
  	} else if (test->open_flags == O_WRONLY) {
  		if (!test->newval) {
  			log_err("New value for sysctl is not set");
  			goto err;
  		}
  		if (write(fd, test->newval, strlen(test->newval)) == -1)
  			goto err;
  	} else {
  		log_err("Unexpected sysctl access: neither read nor write");
  		goto err;
  	}
  
  	goto out;
  err:
  	err = -1;
  out:
  	close(fd);
  	return err;
  }
  
  static int run_test_case(int cgfd, struct sysctl_test *test)
  {
  	enum bpf_attach_type atype = test->attach_type;
  	char sysctl_path[128];
  	int progfd = -1;
  	int err = 0;
  
  	printf("Test case: %s .. ", test->descr);
  
  	snprintf(sysctl_path, sizeof(sysctl_path), "/proc/sys/%s",
  		 test->sysctl);
  
  	progfd = load_sysctl_prog(test, sysctl_path);
  	if (progfd < 0) {
  		if (test->result == LOAD_REJECT)
  			goto out;
  		else
  			goto err;
  	}
  
  	if (bpf_prog_attach(progfd, cgfd, atype, BPF_F_ALLOW_OVERRIDE) == -1) {
  		if (test->result == ATTACH_REJECT)
  			goto out;
  		else
  			goto err;
  	}
  
  	errno = 0;
  	if (access_sysctl(sysctl_path, test) == -1) {
  		if (test->result == OP_EPERM && errno == EPERM)
  			goto out;
  		else
  			goto err;
  	}
  
  	if (test->result != SUCCESS) {
  		log_err("Unexpected success");
  		goto err;
  	}
  
  	goto out;
  err:
  	err = -1;
  out:
  	/* Detaching w/o checking return code: best effort attempt. */
  	if (progfd != -1)
  		bpf_prog_detach(cgfd, atype);
  	close(progfd);
  	printf("[%s]\n", err ? "FAIL" : "PASS");
  	return err;
  }
  
  static int run_tests(int cgfd)
  {
  	int passes = 0;
  	int fails = 0;
  	int i;
  
  	for (i = 0; i < ARRAY_SIZE(tests); ++i) {
  		if (run_test_case(cgfd, &tests[i]))
  			++fails;
  		else
  			++passes;
  	}
  	printf("Summary: %d PASSED, %d FAILED\n", passes, fails);
  	return fails ? -1 : 0;
  }
  
  int main(int argc, char **argv)
  {
  	int cgfd = -1;
  	int err = 0;
  
  	if (setup_cgroup_environment())
  		goto err;
  
  	cgfd = create_and_get_cgroup(CG_PATH);
  	if (cgfd < 0)
  		goto err;
  
  	if (join_cgroup(CG_PATH))
  		goto err;
  
  	if (run_tests(cgfd))
  		goto err;
  
  	goto out;
  err:
  	err = -1;
  out:
  	close(cgfd);
  	cleanup_cgroup_environment();
  	return err;
  }
  