On Thu, Jun 18, 2020 at 09:38:56PM -0700, Andrii Nakryiko wrote:
> On Tue, Jun 16, 2020 at 3:06 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> >
> > 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@xxxxxxxxxx>
> > ---
> > tools/testing/selftests/bpf/test_verifier.c | 13 ++++++-
> > tools/testing/selftests/bpf/verifier/d_path.c | 38 +++++++++++++++++++
> > 2 files changed, 50 insertions(+), 1 deletion(-)
> > create mode 100644 tools/testing/selftests/bpf/verifier/d_path.c
> >
> > diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
> > index 78a6bae56ea6..3cce3dc766a2 100644
> > --- a/tools/testing/selftests/bpf/test_verifier.c
> > +++ b/tools/testing/selftests/bpf/test_verifier.c
> > @@ -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 +985,18 @@ 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)
> emit more meaningful error, than later during load?
ok
>
> > + }
> > +
> > 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) &&
>
> nit: () are redundant
ok
>
> > + !bpf_probe_prog_type(prog_type, 0)) {
> > printf("SKIP (unsupported program type %d)\n", prog_type);
> > skips++;
> > goto close_fds;
> > diff --git a/tools/testing/selftests/bpf/verifier/d_path.c b/tools/testing/selftests/bpf/verifier/d_path.c
> > new file mode 100644
> > index 000000000000..e08181abc056
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/verifier/d_path.c
> > @@ -0,0 +1,38 @@
> > +{
> > + "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(),
> > + },
> > + .errstr = "R0 max value is outside of the array range",
> > + .result = ACCEPT,
>
> accept with error string expected?
oops, probably lefover, will check
thanks,
jirka
>
>
> > + .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",
> > +},
> > --
> > 2.25.4
> >
>
