inet6: prevent network storms caused by linux IPv6 routers

[ Upstream commit 72b43d0898e97f588293b4a24b33c58c46633d81 ]

Linux IPv6 forwards unicast packets, which are link layer multicasts...
The hole was present since day one. I was 100% this check is there, but it is not.

The problem shows itself, f.e. when Microsoft Network Load Balancer runs on a network.
This software resolves IPv6 unicast addresses to multicast MAC addresses.

Signed-off-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 94b5bf132b2e33a467f662b8c0e402a459f00a3d..5f8d242be3f3016592678d09e9cf4654be9234a7 100644 (file)
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -401,6 +401,9 @@ int ip6_forward(struct sk_buff *skb)
                goto drop;
        }
 
+       if (skb->pkt_type != PACKET_HOST)
+               goto drop;
+
        skb_forward_csum(skb);
 
        /*