On Mon, Oct 28, 2019 at 06:52 AM CET, Martin Lau wrote: > On Tue, Oct 22, 2019 at 01:37:25PM +0200, Jakub Sitnicki wrote: >> This patch set is a follow up on a suggestion from LPC '19 discussions to >> make SOCKMAP (or a new map type derived from it) a generic type for storing >> established as well as listening sockets. >> >> We found ourselves in need of a map type that keeps references to listening >> sockets when working on making the socket lookup programmable, aka BPF >> inet_lookup [1]. Initially we repurposed REUSEPORT_SOCKARRAY but found it >> problematic to extend due to being tightly coupled with reuseport >> logic (see slides [2]). >> So we've turned our attention to SOCKMAP instead. >> >> As it turns out the changes needed to make SOCKMAP suitable for storing >> listening sockets are self-contained and have use outside of programming >> the socket lookup. Hence this patch set. >> >> With these patches SOCKMAP can be used in SK_REUSEPORT BPF programs as a >> drop-in replacement for REUSEPORT_SOCKARRAY for TCP. This can hopefully >> lead to code consolidation between the two map types in the future. > What is the plan for UDP support in sockmap? It's on our road-map because without SOCKMAP support for UDP we won't be able to move away from TPROXY [1] and custom SO_BINDTOPREFIX extension [2] for steering new UDP flows to receiving sockets. Also we would like to look into using SOCKMAP for connected UDP socket splicing in the future [3]. I was planning to split work as follows: 1. SOCKMAP support for listening sockets (this series) 2. programmable socket lookup for TCP (cut-down version of [4]) 3. SOCKMAP support for UDP (work not started) 4. programmable socket lookup for UDP (rest of [4]) I'm open to suggestions on how to organize it. >> Having said that, the main intention here is to lay groundwork for using >> SOCKMAP in the next iteration of programmable socket lookup patches. > What may be the minimal to get only lookup work for UDP sockmap? > .close() and .unhash()? John would know better. I haven't tried doing it yet. >From just reading the code - override the two proto ops you mentioned, close and unhash, and adapt the socket checks in SOCKMAP. -Jakub [1] https://blog.cloudflare.com/how-we-built-spectrum/ [2] https://lore.kernel.org/netdev/1458699966-3752-1-git-send-email-gilberto.bertin@xxxxxxxxx/ [3] https://lore.kernel.org/bpf/20190828072250.29828-1-jakub@xxxxxxxxxxxxxx/ [4] https://blog.cloudflare.com/sockmap-tcp-splicing-of-the-future/
