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[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>
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@ -897,7 +897,10 @@ int igmp_rcv(struct sk_buff *skb)
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/* Is it our report looped back? */
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if (((struct rtable*)skb->dst)->fl.iif == 0)
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break;
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igmp_heard_report(in_dev, ih->group);
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/* don't rely on MC router hearing unicast reports */
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if (skb->pkt_type == PACKET_MULTICAST ||
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skb->pkt_type == PACKET_BROADCAST)
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igmp_heard_report(in_dev, ih->group);
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break;
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case IGMP_PIM:
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#ifdef CONFIG_IP_PIMSM_V1
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@ -1231,6 +1231,11 @@ int igmp6_event_report(struct sk_buff *skb)
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if (skb->pkt_type == PACKET_LOOPBACK)
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return 0;
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/* send our report if the MC router may not have heard this report */
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if (skb->pkt_type != PACKET_MULTICAST &&
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skb->pkt_type != PACKET_BROADCAST)
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return 0;
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if (!pskb_may_pull(skb, sizeof(struct in6_addr)))
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return -EINVAL;
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