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=-10.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 EBD03C433E1 for ; Thu, 16 Jul 2020 02:23:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BC23A20663 for ; Thu, 16 Jul 2020 02:23:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Z+rzZo0l" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726989AbgGPCXW (ORCPT ); Wed, 15 Jul 2020 22:23:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48414 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726905AbgGPCXW (ORCPT ); Wed, 15 Jul 2020 22:23:22 -0400 Received: from mail-qt1-x843.google.com (mail-qt1-x843.google.com [IPv6:2607:f8b0:4864:20::843]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B852BC061755; Wed, 15 Jul 2020 19:23:21 -0700 (PDT) Received: by mail-qt1-x843.google.com with SMTP id u12so3694671qth.12; Wed, 15 Jul 2020 19:23:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=AHCM/Vm5YPHkzx659hJjD3hc5D8Y8Z+WICzJA1TTTs4=; b=Z+rzZo0l6JOcbbW9FHKOG3DhIeabG9zdxaDviLComxfuASqK6vgEhh0GG7wQdm5A3e Y48hEygXFK64oWNPSoJdknPWGhPl5Hc29MNHx2RwkZsnQxBdV8VNuA2J69ZgAkKZ5Fzs oVOWabSkxMUzMT8X0promatHtal2HbyUQggAixWFVt+KzQW4sVrwPX/mrqZn7MU7vGzU Xks/fr0H/kjalySJvTBDzUpA3PVl/Mz6zPcPnuxRo4SPYfaqXXMQnzvVDNJbKEsT2JMR XsxAEuG0T814p2ZC5gGX6i7jS+nX0buwQZXuYOPX5nqKjIdTNS/y/5757KQOPwI/K9Bl SMeQ== 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=AHCM/Vm5YPHkzx659hJjD3hc5D8Y8Z+WICzJA1TTTs4=; b=C8ykoevGo6GrqlhF6IhtlcRkUe3kuUVRwPakKHh5EfFWpGuDaaO0Fx+WuVNbPLJTYO fxCa4jU1pBSiExtJhdn2hbKVz7PttFxT7YGlvrZYkE5A2+1BDyihjjPSTs1qOr3C8HMW +P9lVpDx0tEsJzh5BbRO6biOebFNtxXN009RsvrtWDJ7FwLIF+wZDJAPrg5LtlVqCXwb Fw+KwhbM1piaSaRUqN9oU7NMckkVjC17yLBn52PMoacN02buJbDy/pzircelHQ01zSll l7pKZql8EOf31c8jb6UKjKHnrKtxINdd2Ou6uApPdeFB4qVA93U9uxpFWTgIp7SPVHcN +YCg== X-Gm-Message-State: AOAM5306s8wPYNe9ymGRHt7HrkKIWVL9Z/Fenv1Q5w9ADfqnX4W2bPGG zT9YK9dfmg70r4t+dhk0M0aAbCGl+BQvmu/no80= X-Google-Smtp-Source: ABdhPJwJe6oCaGZvcIHjWnINnsndXWILkvDTm2TQyVjA2h1FcY8PjInTdx9W5erpJa1Mbq2tIN1YQ1DtrDtKuLEg+5k= X-Received: by 2002:aed:2cc5:: with SMTP id g63mr2893348qtd.59.1594866200813; Wed, 15 Jul 2020 19:23:20 -0700 (PDT) MIME-Version: 1.0 References: <20200713174654.642628-1-jakub@cloudflare.com> <20200713174654.642628-5-jakub@cloudflare.com> In-Reply-To: <20200713174654.642628-5-jakub@cloudflare.com> From: Andrii Nakryiko Date: Wed, 15 Jul 2020 19:23:09 -0700 Message-ID: Subject: Re: [PATCH bpf-next v4 04/16] inet: Run SK_LOOKUP BPF program on socket lookup To: Jakub Sitnicki Cc: bpf , Networking , kernel-team , Alexei Starovoitov , Daniel Borkmann , "David S. Miller" , Jakub Kicinski , 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 Mon, Jul 13, 2020 at 10:47 AM 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 SK_PASS code. Program can > revert its decision by assigning a NULL socket with bpf_sk_assign(). > > Alternatively, BPF program can also fail the lookup by returning with > SK_DROP, or let the lookup continue as usual with SK_PASS on return, when > no socket has not been selected with bpf_sk_assign(). Other return values you probably meant "no socket has been selected"? > are treated the same as SK_DROP. Why not enforce it instead? Check check_return_code() in verifier.c, it's trivial to do it for SK_LOOKUP. > > 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. > > In case multiple programs are attached, they are run in series in the order > in which they were attached. The end result is determined from return codes > of all the programs according to following rules: > > 1. If any program returned SK_PASS and selected a valid socket, the socket > is used as result of socket lookup. > 2. If more than one program returned SK_PASS and selected a socket, > last selection takes effect. > 3. If any program returned SK_DROP or an invalid return code, and no > program returned SK_PASS and selected a socket, socket lookup fails > with -ECONNREFUSED. > 4. If all programs returned SK_PASS and none of them selected a socket, > socket lookup continues to htable-based lookup. > > Suggested-by: Marek Majkowski > Signed-off-by: Jakub Sitnicki > --- > > Notes: > v4: > - Reduce BPF sk_lookup prog return codes to SK_PASS/SK_DROP. (Lorenz) your description above still assumes prog can return something besides SK_PASS and SK_DROP? > - Default to drop & warn on illegal return value from BPF prog. (Lorenz) > - Rename netns_bpf_attach_type_enable/disable to _need/unneed. (Lorenz) > - Export bpf_sk_lookup_enabled symbol for CONFIG_IPV6=m (kernel test robot) > - Invert return value from bpf_sk_lookup_run_v4 to true on skip reuseport. > - Move dedicated prog_array runner close to its callers in filter.h. > > v3: > - Use a static_key to minimize the hook overhead when not used. (Alexei) > - Adapt for running an array of attached programs. (Alexei) > - Adapt for optionally skipping reuseport selection. (Martin) > > include/linux/filter.h | 102 +++++++++++++++++++++++++++++++++++++ > kernel/bpf/net_namespace.c | 32 +++++++++++- > net/core/filter.c | 3 ++ > net/ipv4/inet_hashtables.c | 31 +++++++++++ > 4 files changed, 167 insertions(+), 1 deletion(-) > > diff --git a/include/linux/filter.h b/include/linux/filter.h > index 380746f47fa1..b9ad0fdabca5 100644 > --- a/include/linux/filter.h > +++ b/include/linux/filter.h > @@ -1295,4 +1295,106 @@ struct bpf_sk_lookup_kern { > bool no_reuseport; > }; > > +extern struct static_key_false bpf_sk_lookup_enabled; > + > +/* Runners for BPF_SK_LOOKUP programs to invoke on socket lookup. > + * > + * Allowed return values for a BPF SK_LOOKUP program are SK_PASS and > + * SK_DROP. Any other return value is treated as SK_DROP. Their > + * meaning is as follows: > + * > + * SK_PASS && ctx.selected_sk != NULL: use selected_sk as lookup result > + * SK_PASS && ctx.selected_sk == NULL: continue to htable-based socket lookup > + * SK_DROP : terminate lookup with -ECONNREFUSED > + * > + * This macro aggregates return values and selected sockets from > + * multiple BPF programs according to following rules: > + * > + * 1. If any program returned SK_PASS and a non-NULL ctx.selected_sk, > + * macro result is SK_PASS and last ctx.selected_sk is used. > + * 2. If any program returned non-SK_PASS return value, > + * macro result is the last non-SK_PASS return value. > + * 3. Otherwise result is SK_PASS and ctx.selected_sk is NULL. > + * > + * Caller must ensure that the prog array is non-NULL, and that the > + * array as well as the programs it contains remain valid. > + */ > +#define BPF_PROG_SK_LOOKUP_RUN_ARRAY(array, ctx, func) \ > + ({ \ > + struct bpf_sk_lookup_kern *_ctx = &(ctx); \ > + struct bpf_prog_array_item *_item; \ > + struct sock *_selected_sk; \ > + struct bpf_prog *_prog; \ > + u32 _ret, _last_ret; \ > + bool _no_reuseport; \ > + \ > + migrate_disable(); \ > + _last_ret = SK_PASS; \ > + _selected_sk = NULL; \ > + _no_reuseport = false; \ these three could be moved before migrate_disable(), or even better just initialize corresponding variables above? > + _item = &(array)->items[0]; \ > + while ((_prog = READ_ONCE(_item->prog))) { \ > + /* restore most recent selection */ \ > + _ctx->selected_sk = _selected_sk; \ > + _ctx->no_reuseport = _no_reuseport; \ > + \ > + _ret = func(_prog, _ctx); \ > + if (_ret == SK_PASS) { \ > + /* remember last non-NULL socket */ \ > + if (_ctx->selected_sk) { \ > + _selected_sk = _ctx->selected_sk; \ > + _no_reuseport = _ctx->no_reuseport; \ > + } \ > + } else { \ > + /* remember last non-PASS ret code */ \ > + _last_ret = _ret; \ > + } \ > + _item++; \ > + } \ > + _ctx->selected_sk = _selected_sk; \ > + _ctx->no_reuseport = _no_reuseport; \ > + migrate_enable(); \ > + _ctx->selected_sk ? SK_PASS : _last_ret; \ > + }) > + [...]