On Thu, Feb 23, 2023 at 1:48 PM Stanislav Fomichev <sdf@xxxxxxxxxx> wrote:
>
> On 02/22, Alexei Starovoitov wrote:
> > From: Alexei Starovoitov <ast@xxxxxxxxxx>
>
> > Adjust cgroup kfunc test to dereference RCU protected cgroup pointer
> > as PTR_TRUSTED and pass into KF_TRUSTED_ARGS kfunc.
>
> > Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
> > ---
> > tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h | 2 +-
> > tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c | 2 +-
> > tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c | 7 ++++++-
> > 3 files changed, 8 insertions(+), 3 deletions(-)
>
> > diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h
> > b/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h
> > index 50d8660ffa26..eb5bf3125816 100644
> > --- a/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h
> > +++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h
> > @@ -10,7 +10,7 @@
> > #include <bpf/bpf_tracing.h>
>
> > struct __cgrps_kfunc_map_value {
> > - struct cgroup __kptr * cgrp;
> > + struct cgroup __kptr_rcu * cgrp;
> > };
>
> > struct hash_map {
> > diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c
> > b/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c
> > index 4ad7fe24966d..d5a53b5e708f 100644
> > --- a/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c
> > +++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c
> > @@ -205,7 +205,7 @@ int BPF_PROG(cgrp_kfunc_get_unreleased, struct cgroup
> > *cgrp, const char *path)
> > }
>
> > SEC("tp_btf/cgroup_mkdir")
> > -__failure __msg("arg#0 is untrusted_ptr_or_null_ expected ptr_ or
> > socket")
> > +__failure __msg("bpf_cgroup_release expects refcounted")
> > int BPF_PROG(cgrp_kfunc_release_untrusted, struct cgroup *cgrp, const
> > char *path)
> > {
> > struct __cgrps_kfunc_map_value *v;
> > diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c
> > b/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c
> > index 0c23ea32df9f..37ed73186fba 100644
> > --- a/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c
> > +++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c
> > @@ -61,7 +61,7 @@ int BPF_PROG(test_cgrp_acquire_leave_in_map, struct
> > cgroup *cgrp, const char *pa
> > SEC("tp_btf/cgroup_mkdir")
> > int BPF_PROG(test_cgrp_xchg_release, struct cgroup *cgrp, const char
> > *path)
> > {
> > - struct cgroup *kptr;
> > + struct cgroup *kptr, *cg;
> > struct __cgrps_kfunc_map_value *v;
> > long status;
>
> > @@ -80,6 +80,11 @@ int BPF_PROG(test_cgrp_xchg_release, struct cgroup
> > *cgrp, const char *path)
> > return 0;
> > }
>
>
> [..]
>
> > + kptr = v->cgrp;
> > + cg = bpf_cgroup_ancestor(kptr, 1);
> > + if (cg)
> > + bpf_cgroup_release(cg);
>
> I went through the series, it all makes sense, I'm assuming Kumar
> will have another look eventually? (since he did for v1).
>
> One question here, should we have something like the following?
>
> if (cg) {
> bpf_cgroup_release(cg);
> } else {
> err = 4;
> return 0;
> }
>
> Or are we just making sure here that the verifier is not complaining
> about bpf_cgroup_ancestor(v->cgrp) and don't really care whether
> bpf_cgroup_ancestor returns something useful or not?
It's the verifier only check.
See other bpf_cgroup_ancestor() related tests in the same file.
They check the run-time component quite well.
No need to duplicate.
