From patchwork Thu Dec 24 19:01:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Guillaume Nault X-Patchwork-Id: 352217 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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS 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 BF013C433E0 for ; Thu, 24 Dec 2020 19:02:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8A02722795 for ; Thu, 24 Dec 2020 19:02:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728704AbgLXTCp (ORCPT ); Thu, 24 Dec 2020 14:02:45 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:48327 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728563AbgLXTCp (ORCPT ); Thu, 24 Dec 2020 14:02:45 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1608836478; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type; bh=Z8MpfZcGhrP8iGy29XT88QvFzgqRvNA/G6lBDtAxjSI=; b=J4fH0kEPQORPQZ5RpaNbLTyssXdPTGqiIZItj7egQkzYpcTesrO4mNwhE9uujCkQlh2B5k 5Q+r4QMu3k7kNVEsAqMfnve6d1i80ieAfDuapwT/1zMhAkTWVq3WggV9iTs+hdK06Zv8L0 r+DXPknLnLdpm6jyQw4Wb5pfBdRjILQ= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-528-WkrCTilSNceRAdzwnIi2QQ-1; Thu, 24 Dec 2020 14:01:13 -0500 X-MC-Unique: WkrCTilSNceRAdzwnIi2QQ-1 Received: by mail-wr1-f72.google.com with SMTP id u29so1209510wru.6 for ; Thu, 24 Dec 2020 11:01:13 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:mime-version :content-disposition; bh=Z8MpfZcGhrP8iGy29XT88QvFzgqRvNA/G6lBDtAxjSI=; b=WoG+wabpy9HymY1ex4fYNJ6zRw634RBZlg8OkPAe6q50gCKOfHH2lNy1Mf01hHmxI6 EUrOxTBTk0jdCkxWhVVpG5vTp69IzIarQHkz7ZU2REp9z1+HKo/0iEk+BKQ36iqZPniw aG+0VKp93GYz8u3gpCslDGm9JKvt+Cvkf/i9A3V/WmUvoh/LbLB6Zb1ZHD7c8LrjXU4N D5kMDfInjtNYBICXpmUKOrVGn3UfTTzYPjNq7VaMLvNtZ2M0T6wWfvZx/ru5dSRipl8e eHbZfyCN4CeDRmGfGS6BCTd3+m7rz3TiNGA4zgQubQvkQEcX+upVULgqNeh/+rPMZD0U Be/A== X-Gm-Message-State: AOAM531R/Lzn7bgLPJkpm9sEEz++VEzbUy/G/duCKpQabHZgXAeABthv 2vUMTSClqxjHa2PzBVHCUtNNHP8KXECgFNYdGr5sgcMvamyP26qxPRwD6eRGe7Uz6hnWZRtZ7Na plvfr1p6SaW99pHsi X-Received: by 2002:a1c:2e88:: with SMTP id u130mr5501001wmu.83.1608836472016; Thu, 24 Dec 2020 11:01:12 -0800 (PST) X-Google-Smtp-Source: ABdhPJzjug5k5Hu6/nXivtFpCBUcIbzBxu94e7Zi5ybGss+pMF8ofMM1a4nzikRpQmOLzOIRBKLjWg== X-Received: by 2002:a1c:2e88:: with SMTP id u130mr5500988wmu.83.1608836471846; Thu, 24 Dec 2020 11:01:11 -0800 (PST) Received: from linux.home (2a01cb058918ce00dd1a5a4f9908f2d5.ipv6.abo.wanadoo.fr. [2a01:cb05:8918:ce00:dd1a:5a4f:9908:f2d5]) by smtp.gmail.com with ESMTPSA id i11sm4367126wmd.47.2020.12.24.11.01.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Dec 2020 11:01:11 -0800 (PST) Date: Thu, 24 Dec 2020 20:01:09 +0100 From: Guillaume Nault To: David Miller , Jakub Kicinski Cc: netdev@vger.kernel.org Subject: [PATCH net] ipv4: Ignore ECN bits for fib lookups in fib_compute_spec_dst() Message-ID: <49ff39b1f55c914847cd58678bae6282112db701.1608836260.git.gnault@redhat.com> MIME-Version: 1.0 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org RT_TOS() only clears one of the ECN bits. Therefore, when fib_compute_spec_dst() resorts to a fib lookup, it can return different results depending on the value of the second ECN bit. For example, ECT(0) and ECT(1) packets could be treated differently. $ ip netns add ns0 $ ip netns add ns1 $ ip link add name veth01 netns ns0 type veth peer name veth10 netns ns1 $ ip -netns ns0 link set dev lo up $ ip -netns ns1 link set dev lo up $ ip -netns ns0 link set dev veth01 up $ ip -netns ns1 link set dev veth10 up $ ip -netns ns0 address add 192.0.2.10/24 dev veth01 $ ip -netns ns1 address add 192.0.2.11/24 dev veth10 $ ip -netns ns1 address add 192.0.2.21/32 dev lo $ ip -netns ns1 route add 192.0.2.10/32 tos 4 dev veth10 src 192.0.2.21 $ ip netns exec ns1 sysctl -wq net.ipv4.icmp_echo_ignore_broadcasts=0 With TOS 4 and ECT(1), ns1 replies using source address 192.0.2.21 (ping uses -Q to set all TOS and ECN bits): $ ip netns exec ns0 ping -c 1 -b -Q 5 192.0.2.255 [...] 64 bytes from 192.0.2.21: icmp_seq=1 ttl=64 time=0.544 ms But with TOS 4 and ECT(0), ns1 replies using source address 192.0.2.11 because the "tos 4" route isn't matched: $ ip netns exec ns0 ping -c 1 -b -Q 6 192.0.2.255 [...] 64 bytes from 192.0.2.11: icmp_seq=1 ttl=64 time=0.597 ms After this patch the ECN bits don't affect the result anymore: $ ip netns exec ns0 ping -c 1 -b -Q 6 192.0.2.255 [...] 64 bytes from 192.0.2.21: icmp_seq=1 ttl=64 time=0.591 ms Fixes: 35ebf65e851c ("ipv4: Create and use fib_compute_spec_dst() helper.") Signed-off-by: Guillaume Nault --- net/ipv4/fib_frontend.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c index cdf6ec5aa45d..84bb707bd88d 100644 --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -292,7 +292,7 @@ __be32 fib_compute_spec_dst(struct sk_buff *skb) .flowi4_iif = LOOPBACK_IFINDEX, .flowi4_oif = l3mdev_master_ifindex_rcu(dev), .daddr = ip_hdr(skb)->saddr, - .flowi4_tos = RT_TOS(ip_hdr(skb)->tos), + .flowi4_tos = ip_hdr(skb)->tos & IPTOS_RT_MASK, .flowi4_scope = scope, .flowi4_mark = vmark ? skb->mark : 0, };