From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2E66CA90AF for ; Wed, 13 May 2020 14:21:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 89748204EA for ; Wed, 13 May 2020 14:21:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="YPA5TAgK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388850AbgEMOVh (ORCPT ); Wed, 13 May 2020 10:21:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35354 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733142AbgEMOVg (ORCPT ); Wed, 13 May 2020 10:21:36 -0400 Received: from mail-ot1-x342.google.com (mail-ot1-x342.google.com [IPv6:2607:f8b0:4864:20::342]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AFFE2C061A0F for ; Wed, 13 May 2020 07:21:36 -0700 (PDT) Received: by mail-ot1-x342.google.com with SMTP id e20so13510402otk.12 for ; Wed, 13 May 2020 07:21:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=z4VXgd+zE4sqqhlf8pmbgOH5r+LEd8gnmKRJo3Gl5fY=; b=YPA5TAgKfumfVUDpmtoRY5G/myaD+x12+ATkr1ZXS4/pdnOs8FgXwqiDJy8Fy5mXL8 8UBI+41Ls9TdIPYuSeHqjZdSZOHtQIG6KsaMlKE7rVSdw1LLS6S41OY/yXLVGntHNCI0 ISl1vJPqgNJ2izUUaFOGLfjAmALLVrNHjJE9Q= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=z4VXgd+zE4sqqhlf8pmbgOH5r+LEd8gnmKRJo3Gl5fY=; b=Fvkeu4Ya7oY6b/JbyaWOKuGcJidGyIE5t6r3DBOtW9KtP8m+FY1nQXFboA/ZnWsBE5 NfdIqkTgFAUlVU6292aOeWh1BguTE5K/70Tsf2S55H74HBvMwP5kE69n8ZYiTkASa7sH RpIIy6fP4cua95VP8gfpfu3JU+Fmokl9Jfln5eBm/XrEqqxjzu7+4pvibi2yQdreaqvS 8eMdAYyUalt31duBL3iBmr/8dfO1wvKD7FT17Sjz3wJZAlbm0Ln08aARMLPk99aGlRLU DYkJoSjU3N3Z9BUu7+hx7fbe2o/fzWN3ulqetx5nMT0YB3FzRHQQ4JdVZQNJ38U+vzem YPWQ== X-Gm-Message-State: AGi0Puan/ApBmbtl0V0K0nv7WFEqzipbYBNQxWb0dUdiMHbAkR4BJVHf 5z6fosvXLbaIecvTiavwybacQvkubRAiG+Fj511bTw== X-Google-Smtp-Source: APiQypJHmHBQ2zzg44WjqJEXgL+RqABOJLmKL/0Nmwe6N3gdrGxA9CXCOHQzfuBd9rxw0MHGxOfGYY9GXYi9rsoyMj8= X-Received: by 2002:a9d:a4c:: with SMTP id 70mr13476366otg.334.1589379695564; Wed, 13 May 2020 07:21:35 -0700 (PDT) MIME-Version: 1.0 References: <20200511185218.1422406-1-jakub@cloudflare.com> <20200511185218.1422406-6-jakub@cloudflare.com> <20200511204445.i7sessmtszox36xd@ast-mbp> <871rnpuuob.fsf@cloudflare.com> In-Reply-To: <871rnpuuob.fsf@cloudflare.com> From: Lorenz Bauer Date: Wed, 13 May 2020 15:21:24 +0100 Message-ID: Subject: Re: [PATCH bpf-next v2 05/17] inet: Run SK_LOOKUP BPF program on socket lookup To: Jakub Sitnicki Cc: Alexei Starovoitov , Networking , bpf , dccp@vger.kernel.org, kernel-team , Alexei Starovoitov , Daniel Borkmann , "David S. Miller" , Eric Dumazet , Gerrit Renker , Jakub Kicinski , Andrii Nakryiko , Martin KaFai Lau , Marek Majkowski Content-Type: text/plain; charset="UTF-8" Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Tue, 12 May 2020 at 14:52, Jakub Sitnicki wrote: > > On Mon, May 11, 2020 at 10:44 PM CEST, Alexei Starovoitov wrote: > > On Mon, May 11, 2020 at 08:52:06PM +0200, Jakub Sitnicki wrote: > >> Run a BPF program before looking up a listening socket on the receive path. > >> Program selects a listening socket to yield as result of socket lookup by > >> calling bpf_sk_assign() helper and returning BPF_REDIRECT code. > >> > >> Alternatively, program can also fail the lookup by returning with BPF_DROP, > >> or let the lookup continue as usual with BPF_OK on return. > >> > >> This lets the user match packets with listening sockets freely at the last > >> possible point on the receive path, where we know that packets are destined > >> for local delivery after undergoing policing, filtering, and routing. > >> > >> With BPF code selecting the socket, directing packets destined to an IP > >> range or to a port range to a single socket becomes possible. > >> > >> Suggested-by: Marek Majkowski > >> Reviewed-by: Lorenz Bauer > >> Signed-off-by: Jakub Sitnicki > >> --- > >> include/net/inet_hashtables.h | 36 +++++++++++++++++++++++++++++++++++ > >> net/ipv4/inet_hashtables.c | 15 ++++++++++++++- > >> 2 files changed, 50 insertions(+), 1 deletion(-) > >> > >> diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h > >> index 6072dfbd1078..3fcbc8f66f88 100644 > >> --- a/include/net/inet_hashtables.h > >> +++ b/include/net/inet_hashtables.h > >> @@ -422,4 +422,40 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, > >> > >> int inet_hash_connect(struct inet_timewait_death_row *death_row, > >> struct sock *sk); > >> + > >> +static inline struct sock *bpf_sk_lookup_run(struct net *net, > >> + struct bpf_sk_lookup_kern *ctx) > >> +{ > >> + struct bpf_prog *prog; > >> + int ret = BPF_OK; > >> + > >> + rcu_read_lock(); > >> + prog = rcu_dereference(net->sk_lookup_prog); > >> + if (prog) > >> + ret = BPF_PROG_RUN(prog, ctx); > >> + rcu_read_unlock(); > >> + > >> + if (ret == BPF_DROP) > >> + return ERR_PTR(-ECONNREFUSED); > >> + if (ret == BPF_REDIRECT) > >> + return ctx->selected_sk; > >> + return NULL; > >> +} > >> + > >> +static inline struct sock *inet_lookup_run_bpf(struct net *net, u8 protocol, > >> + __be32 saddr, __be16 sport, > >> + __be32 daddr, u16 dport) > >> +{ > >> + struct bpf_sk_lookup_kern ctx = { > >> + .family = AF_INET, > >> + .protocol = protocol, > >> + .v4.saddr = saddr, > >> + .v4.daddr = daddr, > >> + .sport = sport, > >> + .dport = dport, > >> + }; > >> + > >> + return bpf_sk_lookup_run(net, &ctx); > >> +} > >> + > >> #endif /* _INET_HASHTABLES_H */ > >> diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c > >> index ab64834837c8..f4d07285591a 100644 > >> --- a/net/ipv4/inet_hashtables.c > >> +++ b/net/ipv4/inet_hashtables.c > >> @@ -307,9 +307,22 @@ struct sock *__inet_lookup_listener(struct net *net, > >> const int dif, const int sdif) > >> { > >> struct inet_listen_hashbucket *ilb2; > >> - struct sock *result = NULL; > >> + struct sock *result, *reuse_sk; > >> unsigned int hash2; > >> > >> + /* Lookup redirect from BPF */ > >> + result = inet_lookup_run_bpf(net, hashinfo->protocol, > >> + saddr, sport, daddr, hnum); > >> + if (IS_ERR(result)) > >> + return NULL; > >> + if (result) { > >> + reuse_sk = lookup_reuseport(net, result, skb, doff, > >> + saddr, sport, daddr, hnum); > >> + if (reuse_sk) > >> + result = reuse_sk; > >> + goto done; > >> + } > >> + > > > > The overhead is too high to do this all the time. > > The feature has to be static_key-ed. > > Static keys is something that Lorenz has also suggested internally, but > we wanted to keep it simple at first. > > Introduction of static keys forces us to decide when non-init_net netns > are allowed to attach to SK_LOOKUP, as attaching enabling SK_LOOKUP in > isolated netns will affect the rx path in init_net. > > I see two options, which seem sensible: > > 1) limit SK_LOOKUP to init_net, which makes testing setup harder, or > > 2) allow non-init_net netns to attach to SK_LOOKUP only if static key > has been already enabled (via sysctl?). > > > > > Also please add multi-prog support. Adding it later will cause > > all sorts of compatibility issues. The semantics of multi-prog > > needs to be thought through right now. > > For example BPF_DROP or BPF_REDIRECT could terminate the prog_run_array > > sequence of progs while BPF_OK could continue. > > It's not ideal, but better than nothing. > > I must say this approach is quite appealing because it's simple to > explain. I would need a custom BPF_PROG_RUN_ARRAY, though. > > I'm curious what downside do you see here? > Is overriding an earlier DROP/REDIRECT verdict useful? > > > Another option could be to execute all attached progs regardless > > of return code, but don't let second prog override selected_sk blindly. > > bpf_sk_assign() could get smarter. > > So if IIUC the rough idea here would be like below? > > - 1st program calls > > bpf_sk_assign(ctx, sk1, 0 /*flags*/) -> 0 (OK) > > - 2nd program calls > > bpf_sk_assign(ctx, sk2, 0) -> -EBUSY (already selected) > bpf_sk_assign(ctx, sk2, BPF_EXIST) -> 0 (OK, replace existing) > > In this case the last program to run has the final say, as opposed to > the semantics where DROP/REDIRECT terminates. Does sk_assign from TC also gain BPF_EXIST semantics? As you know, I'm a bit concerned that TC and sk_lookup sk_assign are actually to completely separate helpers. This is a good way to figure out if its a good idea to overload the name, imo. > > Also, 2nd and subsequent programs would probably need to know if and > which socket has been already selected. I think the selection could be > exposed in context as bpf_sock pointer. > > I admit, I can't quite see the benefit of running thru all programs in > array, so I'm tempted to go with terminate of DROP/REDIRECT in v3. > > > > > Also please switch to bpf_link way of attaching. All system wide attachments > > should be visible and easily debuggable via 'bpftool link show'. > > Currently we're converting tc and xdp hooks to bpf_link. This new hook > > should have it from the beginning. > > Will do in v3. > > Thanks for feedback, > Jakub -- Lorenz Bauer | Systems Engineer 6th Floor, County Hall/The Riverside Building, SE1 7PB, UK www.cloudflare.com From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lorenz Bauer Date: Wed, 13 May 2020 14:21:24 +0000 Subject: Re: [PATCH bpf-next v2 05/17] inet: Run SK_LOOKUP BPF program on socket lookup Message-Id: List-Id: References: <20200511185218.1422406-6-jakub@cloudflare.com> In-Reply-To: <20200511185218.1422406-6-jakub@cloudflare.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: dccp@vger.kernel.org On Tue, 12 May 2020 at 14:52, Jakub Sitnicki wrote: > > On Mon, May 11, 2020 at 10:44 PM CEST, Alexei Starovoitov wrote: > > On Mon, May 11, 2020 at 08:52:06PM +0200, Jakub Sitnicki wrote: > >> Run a BPF program before looking up a listening socket on the receive path. > >> Program selects a listening socket to yield as result of socket lookup by > >> calling bpf_sk_assign() helper and returning BPF_REDIRECT code. > >> > >> Alternatively, program can also fail the lookup by returning with BPF_DROP, > >> or let the lookup continue as usual with BPF_OK on return. > >> > >> This lets the user match packets with listening sockets freely at the last > >> possible point on the receive path, where we know that packets are destined > >> for local delivery after undergoing policing, filtering, and routing. > >> > >> With BPF code selecting the socket, directing packets destined to an IP > >> range or to a port range to a single socket becomes possible. > >> > >> Suggested-by: Marek Majkowski > >> Reviewed-by: Lorenz Bauer > >> Signed-off-by: Jakub Sitnicki > >> --- > >> include/net/inet_hashtables.h | 36 +++++++++++++++++++++++++++++++++++ > >> net/ipv4/inet_hashtables.c | 15 ++++++++++++++- > >> 2 files changed, 50 insertions(+), 1 deletion(-) > >> > >> diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h > >> index 6072dfbd1078..3fcbc8f66f88 100644 > >> --- a/include/net/inet_hashtables.h > >> +++ b/include/net/inet_hashtables.h > >> @@ -422,4 +422,40 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, > >> > >> int inet_hash_connect(struct inet_timewait_death_row *death_row, > >> struct sock *sk); > >> + > >> +static inline struct sock *bpf_sk_lookup_run(struct net *net, > >> + struct bpf_sk_lookup_kern *ctx) > >> +{ > >> + struct bpf_prog *prog; > >> + int ret = BPF_OK; > >> + > >> + rcu_read_lock(); > >> + prog = rcu_dereference(net->sk_lookup_prog); > >> + if (prog) > >> + ret = BPF_PROG_RUN(prog, ctx); > >> + rcu_read_unlock(); > >> + > >> + if (ret = BPF_DROP) > >> + return ERR_PTR(-ECONNREFUSED); > >> + if (ret = BPF_REDIRECT) > >> + return ctx->selected_sk; > >> + return NULL; > >> +} > >> + > >> +static inline struct sock *inet_lookup_run_bpf(struct net *net, u8 protocol, > >> + __be32 saddr, __be16 sport, > >> + __be32 daddr, u16 dport) > >> +{ > >> + struct bpf_sk_lookup_kern ctx = { > >> + .family = AF_INET, > >> + .protocol = protocol, > >> + .v4.saddr = saddr, > >> + .v4.daddr = daddr, > >> + .sport = sport, > >> + .dport = dport, > >> + }; > >> + > >> + return bpf_sk_lookup_run(net, &ctx); > >> +} > >> + > >> #endif /* _INET_HASHTABLES_H */ > >> diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c > >> index ab64834837c8..f4d07285591a 100644 > >> --- a/net/ipv4/inet_hashtables.c > >> +++ b/net/ipv4/inet_hashtables.c > >> @@ -307,9 +307,22 @@ struct sock *__inet_lookup_listener(struct net *net, > >> const int dif, const int sdif) > >> { > >> struct inet_listen_hashbucket *ilb2; > >> - struct sock *result = NULL; > >> + struct sock *result, *reuse_sk; > >> unsigned int hash2; > >> > >> + /* Lookup redirect from BPF */ > >> + result = inet_lookup_run_bpf(net, hashinfo->protocol, > >> + saddr, sport, daddr, hnum); > >> + if (IS_ERR(result)) > >> + return NULL; > >> + if (result) { > >> + reuse_sk = lookup_reuseport(net, result, skb, doff, > >> + saddr, sport, daddr, hnum); > >> + if (reuse_sk) > >> + result = reuse_sk; > >> + goto done; > >> + } > >> + > > > > The overhead is too high to do this all the time. > > The feature has to be static_key-ed. > > Static keys is something that Lorenz has also suggested internally, but > we wanted to keep it simple at first. > > Introduction of static keys forces us to decide when non-init_net netns > are allowed to attach to SK_LOOKUP, as attaching enabling SK_LOOKUP in > isolated netns will affect the rx path in init_net. > > I see two options, which seem sensible: > > 1) limit SK_LOOKUP to init_net, which makes testing setup harder, or > > 2) allow non-init_net netns to attach to SK_LOOKUP only if static key > has been already enabled (via sysctl?). > > > > > Also please add multi-prog support. Adding it later will cause > > all sorts of compatibility issues. The semantics of multi-prog > > needs to be thought through right now. > > For example BPF_DROP or BPF_REDIRECT could terminate the prog_run_array > > sequence of progs while BPF_OK could continue. > > It's not ideal, but better than nothing. > > I must say this approach is quite appealing because it's simple to > explain. I would need a custom BPF_PROG_RUN_ARRAY, though. > > I'm curious what downside do you see here? > Is overriding an earlier DROP/REDIRECT verdict useful? > > > Another option could be to execute all attached progs regardless > > of return code, but don't let second prog override selected_sk blindly. > > bpf_sk_assign() could get smarter. > > So if IIUC the rough idea here would be like below? > > - 1st program calls > > bpf_sk_assign(ctx, sk1, 0 /*flags*/) -> 0 (OK) > > - 2nd program calls > > bpf_sk_assign(ctx, sk2, 0) -> -EBUSY (already selected) > bpf_sk_assign(ctx, sk2, BPF_EXIST) -> 0 (OK, replace existing) > > In this case the last program to run has the final say, as opposed to > the semantics where DROP/REDIRECT terminates. Does sk_assign from TC also gain BPF_EXIST semantics? As you know, I'm a bit concerned that TC and sk_lookup sk_assign are actually to completely separate helpers. This is a good way to figure out if its a good idea to overload the name, imo. > > Also, 2nd and subsequent programs would probably need to know if and > which socket has been already selected. I think the selection could be > exposed in context as bpf_sock pointer. > > I admit, I can't quite see the benefit of running thru all programs in > array, so I'm tempted to go with terminate of DROP/REDIRECT in v3. > > > > > Also please switch to bpf_link way of attaching. All system wide attachments > > should be visible and easily debuggable via 'bpftool link show'. > > Currently we're converting tc and xdp hooks to bpf_link. This new hook > > should have it from the beginning. > > Will do in v3. > > Thanks for feedback, > Jakub -- Lorenz Bauer | Systems Engineer 6th Floor, County Hall/The Riverside Building, SE1 7PB, UK www.cloudflare.com