On Wed, Aug 31, 2022 at 09:37:41AM -0700, Aditi Ghag wrote: > - Use BPF (sockets) iterator to identify sockets connected to a > deleted backend. The BPF (sockets) iterator is network namespace aware > so we'll either need to enter every possible container network > namespace to identify the affected connections, or adapt the iterator > to be without netns checks [3]. This was discussed with my colleague > Daniel Borkmann based on the feedback he shared from the LSFMMBPF > conference discussions. Being able to iterate all sockets across different netns will be useful. It should be doable to ignore the netns check. For udp, a quick thought is to have another iter target. eg. "udp_all_netns". >From the sk, the bpf prog should be able to learn the netns and the bpf prog can filter the netns by itself. The TCP side is going to have an 'optional' per netns ehash table [0] soon, not lhash2 (listening hash) though. Ideally, the same bpf all-netns iter interface should work similarly for both udp and tcp case. Thus, both should be considered and work at the same time. For udp, something more useful than plain udp_abort() could potentially be done. eg. directly connect to another backend (by bpf kfunc?). There may be some details in socket locking...etc but should be doable and the bpf-iter program could be sleepable also. fwiw, we are iterating the tcp socket to retire some older bpf-tcp-cc (congestion control) on the long-lived connections by bpf_setsockopt(TCP_CONGESTION). Also, potentially, instead of iterating all, a more selective case can be done by bpf_prog_test_run()+bpf_sk_lookup_*()+udp_abort(). [0]: https://lore.kernel.org/netdev/20220830191518.77083-1-kuniyu@xxxxxxxxxx/
