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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 DEEABC433E6 for ; Tue, 26 Jan 2021 09:00:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B2730230FF for ; Tue, 26 Jan 2021 09:00:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390730AbhAZJAd (ORCPT ); Tue, 26 Jan 2021 04:00:33 -0500 Received: from mail.kernel.org ([198.145.29.99]:33594 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730226AbhAYSqT (ORCPT ); Mon, 25 Jan 2021 13:46:19 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 95BEA20758; Mon, 25 Jan 2021 18:45:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1611600357; bh=CnUNnC7URhAek0WU9cE7ehGK+skGDbU0czUbUaRg7yg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fUe1LvAGp5QfUYUqKjOB141e+KBOWh75iXfuysjOZohdqnAKoE2vwEm87izGgN0FE ceNT+Ls1aanwwc8oMDDmojZbqGIUmKZi0QOy28xS5+os5Xl4cunslZh3o9rBMpU3X7 SlG57fa4t5uhNjEnlQgKoWTGQHGf6bYkzTFJ6CxQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Guillaume Nault , Jakub Kicinski Subject: [PATCH 5.4 69/86] netfilter: rpfilter: mask ecn bits before fib lookup Date: Mon, 25 Jan 2021 19:39:51 +0100 Message-Id: <20210125183203.961605243@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210125183201.024962206@linuxfoundation.org> References: <20210125183201.024962206@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Guillaume Nault commit 2e5a6266fbb11ae93c468dfecab169aca9c27b43 upstream. RT_TOS() only masks one of the two ECN bits. Therefore rpfilter_mt() treats Not-ECT or ECT(1) packets in a different way than those with ECT(0) or CE. Reproducer: Create two netns, connected with a veth: $ 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 veth01 up $ ip -netns ns1 link set dev veth10 up $ ip -netns ns0 address add 192.0.2.10/32 dev veth01 $ ip -netns ns1 address add 192.0.2.11/32 dev veth10 Add a route to ns1 in ns0: $ ip -netns ns0 route add 192.0.2.11/32 dev veth01 In ns1, only packets with TOS 4 can be routed to ns0: $ ip -netns ns1 route add 192.0.2.10/32 tos 4 dev veth10 Ping from ns0 to ns1 works regardless of the ECN bits, as long as TOS is 4: $ ip netns exec ns0 ping -Q 4 192.0.2.11 # TOS 4, Not-ECT ... 0% packet loss ... $ ip netns exec ns0 ping -Q 5 192.0.2.11 # TOS 4, ECT(1) ... 0% packet loss ... $ ip netns exec ns0 ping -Q 6 192.0.2.11 # TOS 4, ECT(0) ... 0% packet loss ... $ ip netns exec ns0 ping -Q 7 192.0.2.11 # TOS 4, CE ... 0% packet loss ... Now use iptable's rpfilter module in ns1: $ ip netns exec ns1 iptables-legacy -t raw -A PREROUTING -m rpfilter --invert -j DROP Not-ECT and ECT(1) packets still pass: $ ip netns exec ns0 ping -Q 4 192.0.2.11 # TOS 4, Not-ECT ... 0% packet loss ... $ ip netns exec ns0 ping -Q 5 192.0.2.11 # TOS 4, ECT(1) ... 0% packet loss ... But ECT(0) and ECN packets are dropped: $ ip netns exec ns0 ping -Q 6 192.0.2.11 # TOS 4, ECT(0) ... 100% packet loss ... $ ip netns exec ns0 ping -Q 7 192.0.2.11 # TOS 4, CE ... 100% packet loss ... After this patch, rpfilter doesn't drop ECT(0) and CE packets anymore. Fixes: 8f97339d3feb ("netfilter: add ipv4 reverse path filter match") Signed-off-by: Guillaume Nault Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/ipv4/netfilter/ipt_rpfilter.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/ipv4/netfilter/ipt_rpfilter.c +++ b/net/ipv4/netfilter/ipt_rpfilter.c @@ -76,7 +76,7 @@ static bool rpfilter_mt(const struct sk_ flow.daddr = iph->saddr; flow.saddr = rpfilter_get_saddr(iph->daddr); flow.flowi4_mark = info->flags & XT_RPFILTER_VALID_MARK ? skb->mark : 0; - flow.flowi4_tos = RT_TOS(iph->tos); + flow.flowi4_tos = iph->tos & IPTOS_RT_MASK; flow.flowi4_scope = RT_SCOPE_UNIVERSE; flow.flowi4_oif = l3mdev_master_ifindex_rcu(xt_in(par));