Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753451AbeAAOf3 (ORCPT + 1 other); Mon, 1 Jan 2018 09:35:29 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:43606 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753436AbeAAOfY (ORCPT ); Mon, 1 Jan 2018 09:35:24 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Kevin Cernekee , Andrew Lunn , "David S. Miller" Subject: [PATCH 4.9 27/75] net: igmp: Use correct source address on IGMPv3 reports Date: Mon, 1 Jan 2018 15:32:04 +0100 Message-Id: <20180101140100.858496151@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20180101140056.475827799@linuxfoundation.org> References: <20180101140056.475827799@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kevin Cernekee [ Upstream commit a46182b00290839fa3fa159d54fd3237bd8669f0 ] 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 Reviewed-by: Andrew Lunn Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/igmp.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) --- 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 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(st 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);