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[IGMP]: workaround for IGMP v1/v2 bug

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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>
This commit is contained in:
David Stevens
2005-12-02 20:32:59 -08:00
committed by David S. Miller
parent bf031fff1f
commit 24c6927505
2 changed files with 9 additions and 1 deletions
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5
net/ipv4/igmp.c
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@ -897,7 +897,10 @@ int igmp_rcv(struct sk_buff *skb)
/* 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