Re: [PATCH bpf-next] bpf: add bpf_ct_lookup_{tcp,udp}() helpers

[Daniel Borkmann]

On 1/20/20 9:10 PM, Matt Cover wrote:
> On Mon, Jan 20, 2020 at 11:11 AM Matt Cover <werekraken@xxxxxxxxx> wrote:
> > On Sat, Jan 18, 2020 at 8:05 PM John Fastabend <john.fastabend@xxxxxxxxx> wrote:
> > > Matthew Cover wrote:
> > > > Allow looking up an nf_conn. This allows eBPF programs to leverage
> > > > nf_conntrack state for similar purposes to socket state use cases,
> > > > as provided by the socket lookup helpers. This is particularly
> > > > useful when nf_conntrack state is locally available, but socket
> > > > state is not.
> > > >
> > > > Signed-off-by: Matthew Cover <matthew.cover@xxxxxxxxxxxxx>
> > > > ---
> > >
> > > Couple coding comments below. Also looks like a couple build errors
> > > so fix those up. I'm still thinking over this though.
> >
> > Thank you for taking the time to look this over. I will be looking
> > into the build issues.
>
> Looks like I missed static inline on a couple functions when
> nf_conntrack isn't builtin. I'll include the fix in v2.

One of the big issues I'd see with this integration is that literally no-one
will be able to use it unless they manually recompile their distro kernel with
ct as builtin instead of module .. Have you considered writing a tcp/udp ct in
plain bpf? Perhaps would make sense to have some sort of tools/lib/bpf/util/
with bpf prog library code that can be included.