This is a note to let you know that I've just added the patch titled

net: igmp: Use correct source address on IGMPv3 reports

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: net-igmp-use-correct-source-address-on-igmpv3-reports.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Sun Dec 31 11:20:35 CET 2017

From: Kevin Cernekee cernekee@chromium.org Date: Mon, 11 Dec 2017 11:13:45 -0800 Subject: net: igmp: Use correct source address on IGMPv3 reports

From: Kevin Cernekee cernekee@chromium.org

[ 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 cernekee@chromium.org Reviewed-by: Andrew Lunn andrew@lunn.ch Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 <linux/rtnetlink.h> #include <linux/times.h> #include <linux/pkt_sched.h> +#include <linux/byteorder/generic.h>

#include <net/net_namespace.h> #include <net/arp.h> @@ -327,6 +328,23 @@ 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; @@ -374,7 +392,7 @@ 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);

Patches currently in stable-queue which might be from cernekee@chromium.org are

queue-4.4/net-igmp-use-correct-source-address-on-igmpv3-reports.patch queue-4.4/netlink-add-netns-check-on-taps.patch