On Wed, Apr 5, 2023 at 10:29 AM Lorenz Bauer <lmb@xxxxxxxxxxxxx> wrote:
>
> On Tue, Apr 4, 2023 at 5:37 AM Andrii Nakryiko <andrii@xxxxxxxxxx> wrote:
> >
> > Simplify internal verifier log API down to bpf_vlog_init() and
> > bpf_vlog_finalize(). The former handles input arguments validation in
> > one place and makes it easier to change it. The latter subsumes -ENOSPC
> > (truncation) and -EFAULT handling and simplifies both caller's code
> > (bpf_check() and btf_parse()).
> >
> > For btf_parse(), this patch also makes sure that verifier log
> > finalization happens even if there is some error condition during BTF
> > verification process prior to normal finalization step.
> >
> > Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
>
> Acked-by: Lorenz Bauer <lmb@xxxxxxxxxxxxx>
>
> > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> > index 1e974383f0e6..9aeac68ae7ea 100644
> > --- a/kernel/bpf/btf.c
> > +++ b/kernel/bpf/btf.c
> > @@ -5504,16 +5504,30 @@ static int btf_check_type_tags(struct btf_verifier_env *env,
> > return 0;
> > }
> >
> > +static int finalize_log(struct bpf_verifier_log *log, bpfptr_t uattr, u32 uattr_size)
> > +{
> > + u32 log_size_actual;
> > + int err;
> > +
> > + err = bpf_vlog_finalize(log, &log_size_actual);
> > +
> > + if (uattr_size >= offsetofend(union bpf_attr, btf_log_size_actual) &&
> > + copy_to_bpfptr_offset(uattr, offsetof(union bpf_attr, btf_log_size_actual),
> > + &log_size_actual, sizeof(log_size_actual)))
>
> Why not share this with the verifier as well?
it's different field names (right now, log_size_actual for
BPF_PROG_LOAD and btf_log_size_actual for BPF_BTF_LOAD), so different
offsets as well. We could pass offsets, but that seems ugly and I
don't think it would save us much in terms of complexity.
