From patchwork Fri Apr 8 21:21:30 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Friesen X-Patchwork-Id: 608226 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3qhXTK0ybCz9t7P for ; Sat, 9 Apr 2016 07:21:41 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758922AbcDHVVj (ORCPT ); Fri, 8 Apr 2016 17:21:39 -0400 Received: from mail1.windriver.com ([147.11.146.13]:57520 "EHLO mail1.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753964AbcDHVVi (ORCPT ); Fri, 8 Apr 2016 17:21:38 -0400 Received: from ALA-HCA.corp.ad.wrs.com (ala-hca.corp.ad.wrs.com [147.11.189.40]) by mail1.windriver.com (8.15.2/8.15.1) with ESMTPS id u38LLWcu000257 (version=TLSv1 cipher=AES128-SHA bits=128 verify=FAIL); Fri, 8 Apr 2016 14:21:32 -0700 (PDT) Received: from [172.25.39.6] (172.25.39.6) by ALA-HCA.corp.ad.wrs.com (147.11.189.50) with Microsoft SMTP Server (TLS) id 14.3.248.2; Fri, 8 Apr 2016 14:21:31 -0700 Message-ID: <570820DA.2070007@windriver.com> Date: Fri, 8 Apr 2016 15:21:30 -0600 From: Chris Friesen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Julian Anastasov CC: netdev Subject: [PATCH v4] route: do not cache fib route info on local routes with oif References: <5706B250.1060303@windriver.com> <5707C950.6060806@windriver.com> <57080F7E.809@windriver.com> In-Reply-To: X-Originating-IP: [172.25.39.6] Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org For local routes that require a particular output interface we do not want to cache the result. Caching the result causes incorrect behaviour when there are multiple source addresses on the interface. The end result being that if the intended recipient is waiting on that interface for the packet he won't receive it because it will be delivered on the loopback interface and the IP_PKTINFO ipi_ifindex will be set to the loopback interface as well. This can be tested by running a program such as "dhcp_release" which attempts to inject a packet on a particular interface so that it is received by another program on the same board. The receiving process should see an IP_PKTINFO ipi_ifndex value of the source interface (e.g., eth1) instead of the loopback interface (e.g., lo). The packet will still appear on the loopback interface in tcpdump but the important aspect is that the CMSG info is correct. Sample dhcp_release command line: dhcp_release eth1 192.168.204.222 02:11:33:22:44:66 Signed-off-by: Allain Legacy Signed off-by: Chris Friesen Reviewed-by: Julian Anastasov --- net/ipv4/route.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 02c6229..b050cf9 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -2045,6 +2045,18 @@ static struct rtable *__mkroute_output(const struct fib_result *res, */ if (fi && res->prefixlen < 4) fi = NULL; + } else if ((type == RTN_LOCAL) && (orig_oif != 0) && + (orig_oif != dev_out->ifindex)) { + /* For local routes that require a particular output interface + * we do not want to cache the result. Caching the result + * causes incorrect behaviour when there are multiple source + * addresses on the interface, the end result being that if the + * intended recipient is waiting on that interface for the + * packet he won't receive it because it will be delivered on + * the loopback interface and the IP_PKTINFO ipi_ifindex will + * be set to the loopback interface as well. + */ + fi = NULL; } fnhe = NULL;