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net: igmp: Use correct source address on IGMPv3 reports 

commit a46182b00290839fa3fa159d54fd3237bd8669f0 upstream.

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.

Change-Id: I39d64ccedc8b11a4854f2ba8f5ff05fe9a2ea761
Signed-off-by: Kevin Cernekee <cernekee@chromium.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
Kevin Cernekee 2017-12-11 11:13:45 -08:00 committed by syphyr
parent 9b947a1549
commit 31b1159223
1 changed files with 19 additions and 1 deletions
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20
net/ipv4/igmp.c
View File

@ -88,6 +88,7 @@
#include <linux/if_arp.h>
#include <linux/rtnetlink.h>
#include <linux/times.h>
#include <linux/byteorder/generic.h>
#include <net/net_namespace.h>
#include <net/arp.h>
@ -298,6 +299,23 @@ 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);
}
#define igmp_skb_size(skb) (*(unsigned int *)((skb)->cb))
static struct sk_buff *igmpv3_newpack(struct net_device *dev, int size)
@ -345,7 +363,7 @@ static struct sk_buff *igmpv3_newpack(struct net_device *dev, int size)
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(skb, NULL);