[IGMP]: workaround for IGMP v1/v2 bug
From: David Stevens <dlstevens@us.ibm.com>
As explained at:
http://www.cs.ucsb.edu/~krishna/igmp_dos/
With IGMP version 1 and 2 it is possible to inject a unicast
report to a client which will make it ignore multicast
reports sent later by the router.
The fix is to only accept the report if is was sent to a
multicast or unicast address.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index c04607b..4a195c7 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -897,7 +897,10 @@
/* Is it our report looped back? */
if (((struct rtable*)skb->dst)->fl.iif == 0)
break;
- igmp_heard_report(in_dev, ih->group);
+ /* don't rely on MC router hearing unicast reports */
+ if (skb->pkt_type == PACKET_MULTICAST ||
+ skb->pkt_type == PACKET_BROADCAST)
+ igmp_heard_report(in_dev, ih->group);
break;
case IGMP_PIM:
#ifdef CONFIG_IP_PIMSM_V1
