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selftests/bpf: Add verifier test for d_path helper

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Adding verifier test for attaching tracing program and
calling d_path helper from within and testing that it's
allowed for dentry_open function and denied for 'd_path'
function with appropriate error.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200825192124.710397-13-jolsa@kernel.org
This commit is contained in:
Jiri Olsa 2020-08-25 21:21:22 +02:00 committed by Alexei Starovoitov
parent 68a26bc792
commit 762f851568
2 changed files with 55 additions and 1 deletions
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19
tools/testing/selftests/bpf/test_verifier.c
View file

@ -114,6 +114,7 @@ struct bpf_test {
bpf_testdata_struct_t retvals[MAX_TEST_RUNS];
};
enum bpf_attach_type expected_attach_type;
const char *kfunc;
};
/* Note we want this to be 64 bit aligned so that the end of our array is
@ -984,8 +985,24 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
attr.log_level = 4;
attr.prog_flags = pflags;
if (prog_type == BPF_PROG_TYPE_TRACING && test->kfunc) {
attr.attach_btf_id = libbpf_find_vmlinux_btf_id(test->kfunc,
attr.expected_attach_type);
if (attr.attach_btf_id < 0) {
printf("FAIL\nFailed to find BTF ID for '%s'!\n",
test->kfunc);
(*errors)++;
return;
}
}
fd_prog = bpf_load_program_xattr(&attr, bpf_vlog, sizeof(bpf_vlog));
if (fd_prog < 0 && !bpf_probe_prog_type(prog_type, 0)) {
/* BPF_PROG_TYPE_TRACING requires more setup and
* bpf_probe_prog_type won't give correct answer
*/
if (fd_prog < 0 && prog_type != BPF_PROG_TYPE_TRACING &&
!bpf_probe_prog_type(prog_type, 0)) {
printf("SKIP (unsupported program type %d)\n", prog_type);
skips++;
goto close_fds;

37
tools/testing/selftests/bpf/verifier/d_path.c Normal file
View file

@ -0,0 +1,37 @@
{
"d_path accept",
.insns = {
BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_1, 0),
BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
BPF_MOV64_IMM(BPF_REG_6, 0),
BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_6, 0),
BPF_LD_IMM64(BPF_REG_3, 8),
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_d_path),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.result = ACCEPT,
.prog_type = BPF_PROG_TYPE_TRACING,
.expected_attach_type = BPF_TRACE_FENTRY,
.kfunc = "dentry_open",
},
{
"d_path reject",
.insns = {
BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_1, 0),
BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
BPF_MOV64_IMM(BPF_REG_6, 0),
BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_6, 0),
BPF_LD_IMM64(BPF_REG_3, 8),
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_d_path),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.errstr = "helper call is not allowed in probe",
.result = REJECT,
.prog_type = BPF_PROG_TYPE_TRACING,
.expected_attach_type = BPF_TRACE_FENTRY,
.kfunc = "d_path",
},