From: Martin Lau <email@example.com> To: John Fastabend <firstname.lastname@example.org> Cc: Jakub Sitnicki <email@example.com>, "firstname.lastname@example.org" <email@example.com>, "firstname.lastname@example.org" <email@example.com>, "firstname.lastname@example.org" <email@example.com> Subject: Re: [RFC bpf-next 0/5] Extend SOCKMAP to store listening sockets Date: Mon, 28 Oct 2019 21:38:11 +0000 [thread overview] Message-ID: <20191028213804.yv3xfjjlayfghkcr@kafai-mbp> (raw) In-Reply-To: <5db758142fac5_6642abc699aa5c4fd@john-XPS-13-9370.notmuch> On Mon, Oct 28, 2019 at 02:05:24PM -0700, John Fastabend wrote: > Martin Lau wrote: > > 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 . Initially we repurposed REUSEPORT_SOCKARRAY but found it > > > >> problematic to extend due to being tightly coupled with reuseport > > > >> logic (see slides ). > > > >> 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  and custom SO_BINDTOPREFIX extension > > >  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 . > > > > > > 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 ) > > > 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. > > The extra bits sockmap needs are used for redirecting between > between sockets. These will fit in the udp cb area with some > extra room to spare. If that is paticularly challenging we can > also create a program attach type which would preclude using > those bits in the sk_reuseport bpf program types. We already > have types for rx, tx, nop progs, so one more should be fine. > > So at least that paticular concern is not difficult to fix. > > > > > > 4. programmable socket lookup for UDP (rest of ) > > > > > > 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? > > Perhaps not specifically sock_map but they do need to be consolidated > into a map somewhere IMO this has proven to be the most versatile. We > can add sockets from the various BPF hooks or from user space and have > the ability to use the existing map tools, etc. > > > > > If not, would it be cleaner to delicate another map_type > > for lookup-only use case to have both TCP and UDP support. > > But we (Cilium project and above splicing use case is also interested) > will need UDP support so it will be supported regardless of the > SK_REUSEPORT_BPF so I think it makes sense to consolidate all these > use cases on to the existing sockmap. > > Also sockmap supports inserting sockets from BPF and from userspace > which actually requires a bit of logic to track state, etc. Its been > in use and been beat on by various automated test tools so I think > at minimum this needs to be reused. Re-implementing this logic seems > a waste of time and it wasn't exactly trivial and took some work. > > Being able to insert the sockets from XDP (support coming soon) and > from sock_ops programs turns out to be fairly powerful. > > So in short I think it makes most sense to consolidate on sock_map > because > > (a) we need and will add udp support regardless, > (b) we already handle the tricky parts inerting/removing live sockets I didn't mean not to reuse the existing sockmap logic on tracking socks life-time. I was exploring options if the first step for UDP could be lookup-only support first. It is always better to get full UDP support ;) It seems to be confident also, then there is little reason not to do so in UDP sockmap support v1. > (c) from this series it looks like its fairly straight forward > (d) we get lots of shared code > > Thanks, > John > > > > > > > > > > -Jakub > > > > > >  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= > > >  https://firstname.lastname@example.org/ > > >  https://email@example.com/ > > >  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= > >
next prev parent reply other threads:[~2019-10-28 21:38 UTC|newest] Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-10-22 11:37 Jakub Sitnicki 2019-10-22 11:37 ` [RFC bpf-next 1/5] bpf, sockmap: Let BPF helpers use lookup operation on SOCKMAP Jakub Sitnicki 2019-10-24 16:59 ` John Fastabend 2019-10-22 11:37 ` [RFC bpf-next 2/5] bpf, sockmap: Allow inserting listening TCP sockets into SOCKMAP Jakub Sitnicki 2019-10-24 17:06 ` John Fastabend 2019-10-25 9:41 ` Jakub Sitnicki 2019-10-22 11:37 ` [RFC bpf-next 3/5] bpf, sockmap: Don't let child socket inherit psock or its ops on copy Jakub Sitnicki 2019-10-22 11:37 ` [RFC bpf-next 4/5] bpf: Allow selecting reuseport socket from a SOCKMAP Jakub Sitnicki 2019-10-22 11:37 ` [RFC bpf-next 5/5] selftests/bpf: Extend SK_REUSEPORT tests to cover SOCKMAP Jakub Sitnicki 2019-10-24 16:12 ` [RFC bpf-next 0/5] Extend SOCKMAP to store listening sockets Alexei Starovoitov 2019-10-24 16:56 ` John Fastabend 2019-10-25 9:26 ` Jakub Sitnicki 2019-10-25 14:18 ` John Fastabend 2019-10-28 5:52 ` Martin Lau 2019-10-28 12:35 ` Jakub Sitnicki 2019-10-28 19:04 ` John Fastabend 2019-10-29 8:56 ` Jakub Sitnicki 2019-10-28 20:42 ` Martin Lau 2019-10-28 21:05 ` John Fastabend 2019-10-28 21:38 ` Martin Lau [this message] 2019-10-29 8:52 ` Jakub Sitnicki
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