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selftests/bpf: Test file_pos field in bpf_sysctl ctx

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Test access to file_pos field of bpf_sysctl context, both read (incl.
narrow read) and write.

  # ./test_sysctl
  ...
  Test case: ctx:file_pos sysctl:read read ok .. [PASS]
  Test case: ctx:file_pos sysctl:read read ok narrow .. [PASS]
  Test case: ctx:file_pos sysctl:read write ok .. [PASS]
  ...

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 15:25:02 -08:00 committed by Alexei Starovoitov
parent 786047dd08
commit 9a1027e525
1 changed files with 64 additions and 0 deletions
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64
tools/testing/selftests/bpf/test_sysctl.c
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@ -30,6 +30,7 @@ struct sysctl_test {
const char *sysctl;
int open_flags;
const char *newval;
const char *oldval;
enum {
LOAD_REJECT,
ATTACH_REJECT,
@ -130,6 +131,64 @@ static struct sysctl_test tests[] = {
.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, 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 = "kernel/ostype",
.open_flags = O_RDONLY,
.result = SUCCESS,
},
{
.descr = "ctx:file_pos sysctl:read read ok narrow",
.insns = {
/* If (file_pos == X) */
BPF_LDX_MEM(BPF_B, BPF_REG_7, BPF_REG_1,
offsetof(struct bpf_sysctl, file_pos)),
BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 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 = "kernel/ostype",
.open_flags = O_RDONLY,
.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 = {
@ -848,6 +907,11 @@ static int access_sysctl(const char *sysctl_path,
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");