Re: [Patch net v3] cls_flower: call nla_ok() before nla_next()

[Cong Wang]

On Thu, Jan 14, 2021 at 1:36 PM Jakub Kicinski <k...@kernel.org> wrote:
>
> On Thu, 14 Jan 2021 13:07:49 -0800 Cong Wang wrote:
> > -                     if (msk_depth)
> > -                             nla_opt_msk = nla_next(nla_opt_msk, 
> > &msk_depth);
> >                       break;
> >               default:
> >                       NL_SET_ERR_MSG(extack, "Unknown tunnel option type");
> >                       return -EINVAL;
> >               }
> > +
> > +             if (!nla_opt_msk)
> > +                     continue;
>
> Why the switch from !msk_depth to !nla_opt_msk?

It is the same, when nla_opt_msk is NULL, msk_depth is 0.
Checking nla_opt_msk is NULL is more readable to express that
mask is not provided.

>
> Seems like previously providing masks for only subset of options
> would have worked.

I don't think so, every type has this check:

                        if (key->enc_opts.len != mask->enc_opts.len) {
                                NL_SET_ERR_MSG(extack, "Key and mask
miss aligned");
                                return -EINVAL;
                        }

which guarantees the numbers are aligned.

Thanks.