inet6: prevent network storms caused by linux IPv6 routers

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>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 94b5bf132b2e..5f8d242be3f3 100644
--- 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);
 
         /*