From patchwork Fri Sep 18 18:18:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mathieu Desnoyers X-Patchwork-Id: 260595 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=-12.8 required=3.0 tests=BAYES_00,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, 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 EE12EC43465 for ; Fri, 18 Sep 2020 18:25:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 808D521741 for ; Fri, 18 Sep 2020 18:25:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="cJHLomqS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726306AbgIRSZE (ORCPT ); Fri, 18 Sep 2020 14:25:04 -0400 Received: from mail.efficios.com ([167.114.26.124]:59982 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726152AbgIRSZC (ORCPT ); Fri, 18 Sep 2020 14:25:02 -0400 Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id B12732727B5; Fri, 18 Sep 2020 14:18:09 -0400 (EDT) Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id CPhPFy4Gzcoo; Fri, 18 Sep 2020 14:18:09 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id F0FEB2725C6; Fri, 18 Sep 2020 14:18:08 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com F0FEB2725C6 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1600453088; bh=yrIS8m3rknvWl9hL7dggbRVvRNlMDfO6Jcr+vUoXE2M=; h=From:To:Date:Message-Id; b=cJHLomqSDxRtxQI2tUIxCkf++c9Ln5Bhg1ClmYDc1Oi4ynMdpMcffQKX13NGydfeW N4DE7v/0Ia86k47S9VA7rTFGD78Ou4GPfBdXMcLLOip5xs/HFC7wHB/pp/MGnt1BV+ yjMhQuKMmvYuLvRchCL30ZWqkwhm1DoOTWW/dyvtXbEluPnRBQkjC35qA/EmgAo5q/ rZsppCC4XtoBAdRqhtg0s2f6AWq/R+SyExldJXkUx7D3cKrsJSC/YdqEw8Wd2c1KXQ SIVrFkBNWNgNfvE0o9h29XMtb2Yka9hAV61hqhw6dd9eLd4xuD5PRfg8t18aXUmlkU 7MK/A/1pDfWHA== X-Virus-Scanned: amavisd-new at efficios.com Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id kAV2HjzB4I_W; Fri, 18 Sep 2020 14:18:08 -0400 (EDT) Received: from localhost.localdomain (192-222-181-218.qc.cable.ebox.net [192.222.181.218]) by mail.efficios.com (Postfix) with ESMTPSA id D01B92727B2; Fri, 18 Sep 2020 14:18:08 -0400 (EDT) From: Mathieu Desnoyers To: David Ahern , "David S . Miller" , netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Mathieu Desnoyers Subject: [RFC PATCH v2 2/3] ipv6/icmp: l3mdev: Perform icmp error route lookup on source device routing table (v2) Date: Fri, 18 Sep 2020 14:18:00 -0400 Message-Id: <20200918181801.2571-3-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200918181801.2571-1-mathieu.desnoyers@efficios.com> References: <20200918181801.2571-1-mathieu.desnoyers@efficios.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org As per RFC4443, the destination address field for ICMPv6 error messages is copied from the source address field of the invoking packet. In configurations with Virtual Routing and Forwarding tables, looking up which routing table to use for sending ICMPv6 error messages is currently done by using the destination net_device. If the source and destination interfaces are within separate VRFs, or one in the global routing table and the other in a VRF, looking up the source address of the invoking packet in the destination interface's routing table will fail if the destination interface's routing table contains no route to the invoking packet's source address. One observable effect of this issue is that traceroute6 does not work in the following cases: - Route leaking between global routing table and VRF - Route leaking between VRFs Use the source device routing table when sending ICMPv6 error messages. [ In the context of ipv4, it has been pointed out that a similar issue may exist with ICMP errors triggered when forwarding between network namespaces. It would be worthwhile to investigate whether ipv6 has similar issues, but is outside of the scope of this investigation. ] [ Testing shows that similar issues exist with ipv6 unreachable / fragmentation needed messages. However, investigation of this additional failure mode is beyond this investigation's scope. ] Link: https://tools.ietf.org/html/rfc4443 Signed-off-by: Mathieu Desnoyers Cc: David Ahern Cc: David S. Miller Cc: netdev@vger.kernel.org --- Changes since v1: - Introduce icmp6_get_route_lookup_dev. - Use skb->dev for routing table lookup, because it is guaranteed to be non-NULL. --- net/ipv6/icmp.c | 7 +++++-- net/ipv6/ip6_output.c | 2 -- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c index a4e4912ad607..91209a2760aa 100644 --- a/net/ipv6/icmp.c +++ b/net/ipv6/icmp.c @@ -501,8 +501,11 @@ void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info, if (__ipv6_addr_needs_scope_id(addr_type)) { iif = icmp6_iif(skb); } else { - dst = skb_dst(skb); - iif = l3mdev_master_ifindex(dst ? dst->dev : skb->dev); + /* + * The source device is used for looking up which routing table + * to use for sending an ICMP error. + */ + iif = l3mdev_master_ifindex(skb->dev); } /* diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index c78e67d7747f..cd623068de53 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -468,8 +468,6 @@ int ip6_forward(struct sk_buff *skb) * check and decrement ttl */ if (hdr->hop_limit <= 1) { - /* Force OUTPUT device used as source address */ - skb->dev = dst->dev; icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT, 0); __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);