On Mon, Oct 28, 2019 at 01:35:26PM +0100, Jakub Sitnicki wrote: > 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) hmm...It is hard to comment how the full UDP sockmap may work out without a code attempt because I am not fluent in sock_map ;) >From a quick look, it seems there are quite a few things to do. For example, the TCP_SKB_CB(skb) usage and how that may look like in UDP. "struct udp_skb_cb" is 28 bytes while "struct napi_gro_cb" seems to be 48 bytes already which may need a closer look. > 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. Do your use cases need bpf prog attached to sock_map? If not, would it be cleaner to delicate another map_type for lookup-only use case to have both TCP and UDP support. > > -Jakub > > [1] https://urldefense.proofpoint.com/v2/url?u=https-3A__blog.cloudflare.com_how-2Dwe-2Dbuilt-2Dspectrum_&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=VQnoQ7LvghIj0gVEaiQSUw&m=lSo-FsOeNl_8znZZ07H8I6ZYAinPKTR5C3Cn_Ol3QYQ&s=DZgW8-2Xl1P8NU59ji4ieQLzwWpx4t3gGq_tqB0l3Bo&e= > [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://urldefense.proofpoint.com/v2/url?u=https-3A__blog.cloudflare.com_sockmap-2Dtcp-2Dsplicing-2Dof-2Dthe-2Dfuture_&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=VQnoQ7LvghIj0gVEaiQSUw&m=lSo-FsOeNl_8znZZ07H8I6ZYAinPKTR5C3Cn_Ol3QYQ&s=NerUqb4j7IsGBTcni6Yxk40wf6kTkckHXn3Nx5i4mCU&e=
