Commit a46182b0 authored by Kevin Cernekee's avatar Kevin Cernekee Committed by David S. Miller

net: igmp: Use correct source address on IGMPv3 reports

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: default avatarKevin Cernekee <cernekee@chromium.org>
Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c545a945
......@@ -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>
......@@ -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);
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment