Re: [PATCH bpf-next v2] bpf: check flags in 'bpf_ringbuf_discard()' and 'bpf_ringbuf_submit()'

[Alexei Starovoitov]

On Tue, Mar 30, 2021 at 3:54 PM Pedro Tammela <pctammela@xxxxxxxxx> wrote:
>
>  BPF_CALL_2(bpf_ringbuf_submit, void *, sample, u64, flags)
>  {
> +       if (unlikely(flags & ~(BPF_RB_NO_WAKEUP | BPF_RB_FORCE_WAKEUP)))
> +               return -EINVAL;
> +
>         bpf_ringbuf_commit(sample, flags, false /* discard */);
> +
>         return 0;

I think ringbuf design was meant for bpf_ringbuf_submit to never fail.
If we do flag validation it probably should be done at the verifier time.