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selftests/bpf: Test sysctl_get_current_value helper

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Test sysctl_get_current_value on sysctl read and write, buffers with
enough space and too small buffers to get E2BIG and truncated result,
etc.

  # ./test_sysctl
  ...
  Test case: sysctl_get_current_value sysctl:read ok, gt .. [PASS]
  Test case: sysctl_get_current_value sysctl:read ok, eq .. [PASS]
  Test case: sysctl_get_current_value sysctl:read E2BIG truncated ..  [PASS]
  Test case: sysctl_get_current_value sysctl:read EINVAL .. [PASS]
  Test case: sysctl_get_current_value sysctl:write ok .. [PASS]
  Summary: 16 PASSED, 0 FAILED

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrey Ignatov 2019-03-08 15:17:51 -08:00 committed by Alexei Starovoitov
parent 6041c67f28
commit 11ff34f74e
1 changed files with 228 additions and 0 deletions
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228
tools/testing/selftests/bpf/test_sysctl.c
View file

@ -18,11 +18,13 @@
#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];
enum bpf_attach_type attach_type;
const char *sysctl;
@ -350,6 +352,190 @@ static struct sysctl_test tests[] = {
.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, 0x000a78756e694cULL),
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, 0x000a78756e694cULL),
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, 0x000078756e694cULL),
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,
},
};
static size_t probe_prog_length(const struct bpf_insn *fp)
@ -362,6 +548,27 @@ static size_t probe_prog_length(const struct bpf_insn *fp)
return len + 1;
}
static int fixup_sysctl_value(const char *buf, size_t buf_len,
struct bpf_insn *prog, size_t insn_num)
{
uint32_t value_num = 0;
uint8_t c, i;
if (buf_len > sizeof(value_num)) {
log_err("Value is too big (%zd) to use in fixup", buf_len);
return -1;
}
for (i = 0; i < buf_len; ++i) {
c = buf[i];
value_num |= (c << i * 8);
}
prog[insn_num].imm = value_num;
return 0;
}
static int load_sysctl_prog(struct sysctl_test *test, const char *sysctl_path)
{
struct bpf_insn *prog = test->insns;
@ -374,6 +581,27 @@ static int load_sysctl_prog(struct sysctl_test *test, const char *sysctl_path)
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"