From patchwork Fri Sep 25 20:04:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mathieu Desnoyers X-Patchwork-Id: 260185 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=-12.9 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 87AA4C4727E for ; Fri, 25 Sep 2020 20:38:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3921921D7A for ; Fri, 25 Sep 2020 20:38:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="O00q3CG1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727701AbgIYUdM (ORCPT ); Fri, 25 Sep 2020 16:33:12 -0400 Received: from mail.efficios.com ([167.114.26.124]:50758 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726743AbgIYUUI (ORCPT ); Fri, 25 Sep 2020 16:20:08 -0400 Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id 30D382D1ADB; Fri, 25 Sep 2020 16:05:00 -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 sk2Ybp6UR8WG; Fri, 25 Sep 2020 16:04:59 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id 8DB572D1A6A; Fri, 25 Sep 2020 16:04:59 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com 8DB572D1A6A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1601064299; bh=yrIS8m3rknvWl9hL7dggbRVvRNlMDfO6Jcr+vUoXE2M=; h=From:To:Date:Message-Id; b=O00q3CG1AzTRajoVJQQJ6s0DiWmpafLjvuxywMG3b8XFhDnx6W9QAHN+qmB4xj4Dn V0uwYlZPGeakNqkdoECu0jDAO+VnYZaprUMWs/kpNuE9yWrmFa3QJwRG+gb4uj9dTL Ot6Ro5/t/NEwKU44iRKma6OOVIDvwKV1iLwsWODOEfW+IKgo4e5qy0phhTbpfPdqei AoxRMvadGCqoJLHIVA8yv+RDg++3DkFA0mIyVSf20CmeIvmwEMuABz43MfQtY7C85d KpDP61UOf6DT+j2SDlZsAzz55RUcC8yeIQ3/zq58Jn50KQEPeVwAkS7Jc2yrwNZG2I Rh8aYp6Z8g+/A== 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 j_hJPL4vaurz; Fri, 25 Sep 2020 16:04:59 -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 5F38D2D1652; Fri, 25 Sep 2020 16:04:59 -0400 (EDT) From: Mathieu Desnoyers To: David Ahern , "David S . Miller" , netdev@vger.kernel.org, Michael Jeanson Cc: linux-kernel@vger.kernel.org, Mathieu Desnoyers Subject: [RFC PATCH 2/3] ipv6/icmp: l3mdev: Perform icmp error route lookup on source device routing table (v2) Date: Fri, 25 Sep 2020 16:04:51 -0400 Message-Id: <20200925200452.2080-3-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200925200452.2080-1-mathieu.desnoyers@efficios.com> References: <20200925200452.2080-1-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);