From patchwork Mon Apr 20 12:39:14 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 227453 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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT 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 887E5C3A5A0 for ; Mon, 20 Apr 2020 12:48:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 629D4206E9 for ; Mon, 20 Apr 2020 12:48:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587386907; bh=Zxmgv2pBfl9kBTfjjx2DGGbJnMniCyABQcS1iX5czk8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=1Gb9t0GKFC2otNvk9ePvC49URb2rICXPTEPm4UOII0ZE+AUSdDBXL2ll7mt2nVbDA mt9UBOJ47jl8xDsIwYYdRgrPmyUr2kLIO9xR44db0SewmoTJlVNF6zPKUU2QUGJGN4 9pkw3OmIxP4GeSrRZdCabWns5TzN5aqrIdNkKQ4Q= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729245AbgDTMs0 (ORCPT ); Mon, 20 Apr 2020 08:48:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:44952 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729184AbgDTMsW (ORCPT ); Mon, 20 Apr 2020 08:48:22 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4AA34206E9; Mon, 20 Apr 2020 12:48:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587386901; bh=Zxmgv2pBfl9kBTfjjx2DGGbJnMniCyABQcS1iX5czk8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZM2VJEQ2pst/A9Mf1gAGeFI022Rohgx62g+FEw6FKWNoiYwjoYPKwDDsCP3cz4y1q 6lpj5yj78vSD5qHLLVfhrcRivW05tJj15kEmPcdK2TsofLjFAnLV4aBDrK3PnjRwbz 4q7Sin3chYRp/c8lZUYtpxZcn0l0TEY7JL0dTWKM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tim Stallard , "David S. Miller" Subject: [PATCH 4.19 04/40] net: ipv6: do not consider routes via gateways for anycast address check Date: Mon, 20 Apr 2020 14:39:14 +0200 Message-Id: <20200420121451.519491651@linuxfoundation.org> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20200420121444.178150063@linuxfoundation.org> References: <20200420121444.178150063@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Tim Stallard [ Upstream commit 03e2a984b6165621f287fadf5f4b5cd8b58dcaba ] The behaviour for what is considered an anycast address changed in commit 45e4fd26683c ("ipv6: Only create RTF_CACHE routes after encountering pmtu exception"). This now considers the first address in a subnet where there is a route via a gateway to be an anycast address. This breaks path MTU discovery and traceroutes when a host in a remote network uses the address at the start of a prefix (eg 2600:: advertised as 2600::/48 in the DFZ) as ICMP errors will not be sent to anycast addresses. This patch excludes any routes with a gateway, or via point to point links, like the behaviour previously from rt6_is_gw_or_nonexthop in net/ipv6/route.c. This can be tested with: ip link add v1 type veth peer name v2 ip netns add test ip netns exec test ip link set lo up ip link set v2 netns test ip link set v1 up ip netns exec test ip link set v2 up ip addr add 2001:db8::1/64 dev v1 nodad ip addr add 2001:db8:100:: dev lo nodad ip netns exec test ip addr add 2001:db8::2/64 dev v2 nodad ip netns exec test ip route add unreachable 2001:db8:1::1 ip netns exec test ip route add 2001:db8:100::/64 via 2001:db8::1 ip netns exec test sysctl net.ipv6.conf.all.forwarding=1 ip route add 2001:db8:1::1 via 2001:db8::2 ping -I 2001:db8::1 2001:db8:1::1 -c1 ping -I 2001:db8:100:: 2001:db8:1::1 -c1 ip addr delete 2001:db8:100:: dev lo ip netns delete test Currently the first ping will get back a destination unreachable ICMP error, but the second will never get a response, with "icmp6_send: acast source" logged. After this patch, both get destination unreachable ICMP replies. Fixes: 45e4fd26683c ("ipv6: Only create RTF_CACHE routes after encountering pmtu exception") Signed-off-by: Tim Stallard Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/net/ip6_route.h | 1 + 1 file changed, 1 insertion(+) --- a/include/net/ip6_route.h +++ b/include/net/ip6_route.h @@ -234,6 +234,7 @@ static inline bool ipv6_anycast_destinat return rt->rt6i_flags & RTF_ANYCAST || (rt->rt6i_dst.plen < 127 && + !(rt->rt6i_flags & (RTF_GATEWAY | RTF_NONEXTHOP)) && ipv6_addr_equal(&rt->rt6i_dst.addr, daddr)); }