Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752653AbdLKTOW (ORCPT ); Mon, 11 Dec 2017 14:14:22 -0500 Received: from mail-qt0-f202.google.com ([209.85.216.202]:52916 "EHLO mail-qt0-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751566AbdLKTOU (ORCPT ); Mon, 11 Dec 2017 14:14:20 -0500 X-Google-Smtp-Source: ACJfBovn1+FEbmKA9C0zhOTZXiZnHlhQcJHM/Qby1tLJhwKVlaUB0U5tKzn6qrPy3fX1PAmMdxJPmidqgWz46Q== MIME-Version: 1.0 Date: Mon, 11 Dec 2017 11:13:45 -0800 Message-Id: <20171211191345.104136-1-cernekee@chromium.org> X-Mailer: git-send-email 2.15.1.424.g9478a66081-goog Subject: [PATCH] net: igmp: Use correct source address on IGMPv3 reports From: Kevin Cernekee To: davem@davemloft.net, kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org Cc: netdev@vger.kernel.org, andrew@lunn.ch, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2373 Lines: 79 Closing a multicast socket after the final IPv4 address is deleted from an interface can generate a membership report that uses the source IP from a different interface. The following test script, run from an isolated netns, reproduces the issue: #!/bin/bash ip link add dummy0 type dummy ip link add dummy1 type dummy ip link set dummy0 up ip link set dummy1 up ip addr add 10.1.1.1/24 dev dummy0 ip addr add 192.168.99.99/24 dev dummy1 tcpdump -U -i dummy0 & socat EXEC:"sleep 2" \ UDP4-DATAGRAM:239.101.1.68:8889,ip-add-membership=239.0.1.68:10.1.1.1 & sleep 1 ip addr del 10.1.1.1/24 dev dummy0 sleep 5 kill %tcpdump RFC 3376 specifies that the report must be sent with a valid IP source address from the destination subnet, or from address 0.0.0.0. Add an extra check to make sure this is the case. Signed-off-by: Kevin Cernekee --- net/ipv4/igmp.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index d1f8f302dbf3..0672264c9d93 100644 --- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -89,6 +89,7 @@ #include #include #include +#include #include #include @@ -321,6 +322,23 @@ igmp_scount(struct ip_mc_list *pmc, int type, int gdeleted, int sdeleted) return scount; } +/* source address selection per RFC 3376 section 4.2.13 */ +static __be32 igmpv3_get_srcaddr(struct net_device *dev, + const struct flowi4 *fl4) +{ + struct in_device *in_dev = __in_dev_get_rcu(dev); + + if (!in_dev) + return htonl(INADDR_ANY); + + for_ifa(in_dev) { + if (inet_ifa_match(fl4->saddr, ifa)) + return fl4->saddr; + } endfor_ifa(in_dev); + + return htonl(INADDR_ANY); +} + static struct sk_buff *igmpv3_newpack(struct net_device *dev, unsigned int mtu) { struct sk_buff *skb; @@ -368,7 +386,7 @@ static struct sk_buff *igmpv3_newpack(struct net_device *dev, unsigned int mtu) pip->frag_off = htons(IP_DF); pip->ttl = 1; pip->daddr = fl4.daddr; - pip->saddr = fl4.saddr; + pip->saddr = igmpv3_get_srcaddr(dev, &fl4); pip->protocol = IPPROTO_IGMP; pip->tot_len = 0; /* filled in later */ ip_select_ident(net, skb, NULL); -- 2.15.1.424.g9478a66081-goog