On Thu, May 14, 2020 at 8:01 AM Yonghong Song <yhs@xxxxxx> wrote:
>
>
>
> On 5/13/20 11:14 PM, Andrii Nakryiko wrote:
> > On Wed, May 13, 2020 at 10:32 PM Yonghong Song <yhs@xxxxxx> wrote:
> >>
> >> Currently, tracing/fentry and tracing/fexit prog
> >> return values are not enforced. In trampoline codes,
> >> the fentry/fexit prog return values are ignored.
> >> Let us enforce it to be 0 to avoid confusion and
> >> allows potential future extension.
> >>
> >> This patch also explicitly added return value
> >> checking for tracing/raw_tp, tracing/fmod_ret,
> >> and freplace programs such that these program
> >> return values can be anything. The purpose are
> >> two folds:
> >> 1. to make it explicit about return value expectations
> >> for these programs in verifier.
> >> 2. for tracing prog_type, if a future attach type
> >> is added, the default is -ENOTSUPP which will
> >> enforce to specify return value ranges explicitly.
> >>
> >> Fixes: fec56f5890d9 ("bpf: Introduce BPF trampoline")
> >> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> >> ---
> >
> > Looks good, except a nit below.
> >
> > Acked-by: Andrii Nakryiko <andriin@xxxxxx>
> >
> > [...]
> >
> >> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> >> index fa1d8245b925..2d80cce0a28a 100644
> >> --- a/kernel/bpf/verifier.c
> >> +++ b/kernel/bpf/verifier.c
> >> @@ -7059,6 +7059,24 @@ static int check_return_code(struct bpf_verifier_env *env)
> >> return 0;
> >> range = tnum_const(0);
> >> break;
> >> + case BPF_PROG_TYPE_TRACING:
> >> + switch ((env->prog->expected_attach_type)) {
> >
> > nit: extra pair of ()?
>
> Sorry about this. Not sure whether it is worthwhile to send another
> revision. Please let me know if another revision is needed.
Applied to bpf tree with that typo fixed. Thanks
