diff options
author | Kevin Cernekee <cernekee@chromium.org> | 2017-12-11 11:13:45 -0800 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2017-12-13 13:51:27 -0500 |
commit | a46182b00290839fa3fa159d54fd3237bd8669f0 (patch) | |
tree | 48f19d1cd5275ab4c88cb9d8a5c967f556c35382 | |
parent | c545a945d0d9ea2ea2c7d23d43cf0d86e32cd7cf (diff) | |
download | linux-a46182b00290839fa3fa159d54fd3237bd8669f0.tar.bz2 |
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: Kevin Cernekee <cernekee@chromium.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r-- | net/ipv4/igmp.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index 50448a220a1f..726f6b608274 100644 --- 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> @@ -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); |