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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E13D4C43334 for ; Tue, 19 Jul 2022 12:50:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238100AbiGSMuY (ORCPT ); Tue, 19 Jul 2022 08:50:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237674AbiGSMsl (ORCPT ); Tue, 19 Jul 2022 08:48:41 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 939B38D5CA; Tue, 19 Jul 2022 05:19:09 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 7BF2DB81B21; Tue, 19 Jul 2022 12:19:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E2CF1C341C6; Tue, 19 Jul 2022 12:19:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658233148; bh=o7qzqHx+I24J2T5hE92OpaglvEMG/SRhBOpBoQSsWHs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DFQrfIQHQP1z08Tjte6vMAqu9vjpOqFO3oQmd2ZEVk0N4eu6TsHVrN6w0MBqpWf+3 +b4M1LAQQ0bzVaNbYwoeyse7d8IKG/Yca2KCJ7eBcfKsVREbVOrxrS6mMmEV4xTaR+ Z1UCcplxGj6sp/I+LQQUBIntctHVR1eM+XgPbFO0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Edwin Brossette , Nicolas Dichtel , Paolo Abeni Subject: [PATCH 5.18 022/231] ip: fix dflt addr selection for connected nexthop Date: Tue, 19 Jul 2022 13:51:47 +0200 Message-Id: <20220719114715.859200840@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220719114714.247441733@linuxfoundation.org> References: <20220719114714.247441733@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: Nicolas Dichtel commit 747c14307214b55dbd8250e1ab44cad8305756f1 upstream. When a nexthop is added, without a gw address, the default scope was set to 'host'. Thus, when a source address is selected, 127.0.0.1 may be chosen but rejected when the route is used. When using a route without a nexthop id, the scope can be configured in the route, thus the problem doesn't exist. To explain more deeply: when a user creates a nexthop, it cannot specify the scope. To create it, the function nh_create_ipv4() calls fib_check_nh() with scope set to 0. fib_check_nh() calls fib_check_nh_nongw() wich was setting scope to 'host'. Then, nh_create_ipv4() calls fib_info_update_nhc_saddr() with scope set to 'host'. The src addr is chosen before the route is inserted. When a 'standard' route (ie without a reference to a nexthop) is added, fib_create_info() calls fib_info_update_nhc_saddr() with the scope set by the user. iproute2 set the scope to 'link' by default. Here is a way to reproduce the problem: ip netns add foo ip -n foo link set lo up ip netns add bar ip -n bar link set lo up sleep 1 ip -n foo link add name eth0 type dummy ip -n foo link set eth0 up ip -n foo address add 192.168.0.1/24 dev eth0 ip -n foo link add name veth0 type veth peer name veth1 netns bar ip -n foo link set veth0 up ip -n bar link set veth1 up ip -n bar address add 192.168.1.1/32 dev veth1 ip -n bar route add default dev veth1 ip -n foo nexthop add id 1 dev veth0 ip -n foo route add 192.168.1.1 nhid 1 Try to get/use the route: > $ ip -n foo route get 192.168.1.1 > RTNETLINK answers: Invalid argument > $ ip netns exec foo ping -c1 192.168.1.1 > ping: connect: Invalid argument Try without nexthop group (iproute2 sets scope to 'link' by dflt): ip -n foo route del 192.168.1.1 ip -n foo route add 192.168.1.1 dev veth0 Try to get/use the route: > $ ip -n foo route get 192.168.1.1 > 192.168.1.1 dev veth0 src 192.168.0.1 uid 0 > cache > $ ip netns exec foo ping -c1 192.168.1.1 > PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data. > 64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=0.039 ms > > --- 192.168.1.1 ping statistics --- > 1 packets transmitted, 1 received, 0% packet loss, time 0ms > rtt min/avg/max/mdev = 0.039/0.039/0.039/0.000 ms CC: stable@vger.kernel.org Fixes: 597cfe4fc339 ("nexthop: Add support for IPv4 nexthops") Reported-by: Edwin Brossette Signed-off-by: Nicolas Dichtel Link: https://lore.kernel.org/r/20220713114853.29406-1-nicolas.dichtel@6wind.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman --- net/ipv4/fib_semantics.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -1230,7 +1230,7 @@ static int fib_check_nh_nongw(struct net nh->fib_nh_dev = in_dev->dev; dev_hold_track(nh->fib_nh_dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC); - nh->fib_nh_scope = RT_SCOPE_HOST; + nh->fib_nh_scope = RT_SCOPE_LINK; if (!netif_carrier_ok(nh->fib_nh_dev)) nh->fib_nh_flags |= RTNH_F_LINKDOWN; err = 0;