Re: [PATCH nf-next] netfilter: nf_tables: add ebpf expression

Florian Westphal
2022-08-31T15:35:14Z

Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > asking the kernel to store an additional label with the program rule?
>
> @Florian, could you probably use the object infrastructure to refer to
> the program?

Yes, I would like to extend objref infra later once this is accepted.

> This might also allow you to refer to this new object type from
> nf_tables maps.

Yes, but first nft needs to be able to construct some meaningful output
again. If we don't attach a specific label (such as filename), we need
to be able to reconstruct info based on what we can query via id/tag and
bpf syscall.

objref infra doesn't help here unless we'll force something like
'nft-defined-objref-name-must-match-elf-binary-name', and I find that
terrible.

> It would be good to avoid linear rule-based matching to select what
> program to run.

Hmmm, I did not consider it a huge deal, its an ebpf program so
users can dispatch to another program.

Objref is nice if the program to run should be selected from a criterion that isn't
readily available to a sk_filter program though.