On Mon, Jan 20, 2020 at 2:11 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote: > > 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. I don't believe the builtin requirement is permanent. Currently, that requirement comes from an undefined reference to nf_conntrack_find_get() during linking. As a future improvement, I am planning to propose a function pointer which ct_lookup() uses. The kernel proper would point this to an always NULL stub. nf_conntrack would populate to the real function when builtin or when loaded as a module. If there is a better way to solve the kernel proper using an exported symbol provided by a module, I'd be happy to hear of it.
