On Fri, Jun 30, 2017 at 10:23:24PM +0200, Richard Weinberger wrote: > Florian, > > Am 30.06.2017 um 21:55 schrieb Florian Westphal: > >>> Why not use a hash of the address? > >> > >> Would also work. Or xor it with a random number. > >> > >> On the other hand, for user space it would be more useful when the > >> conntrack id > >> does not repeat that often. That's why I favor the good old counter method. > >> Currently the conntrack id is reused very fast. > >> e.g. in one of our applications we use the conntack id via NFQUEUE and > >> watch the > >> destroy events via conntrack. It happens regularly that a new connection > >> has the > >> same id than a different connection we saw some moments before, before we > >> receive > >> the destroy event from the conntrack socket. > > > > Perhaps we can place that in a new extension (its not needed in any > > fastpath ops)? > > To get rid of the infoleak we have to re-introduce the id field in struct > nf_conn > and struct nf_conntrack_expect. > Otherwise have nothing to compare against in the conntrack/expect remove case. > > So the only question is what to store, IMHO a counter that can wrap around is > the > cheapest method and would also not harm the fast-path.
I have a patch to assign ids through percpu approach that I can recover. It's dividing the u64 id space between the existing num_cpus.
