ipv6: drop packets when source address is multicast

RFC 4291 Section 2.7 says Multicast addresses must not be used as source
addresses in IPv6 packets - drop them on input so we don't process the
packet further.

Signed-off-by: Brian Haley <brian.haley@hp.com>
Reported-and-Tested-by: Kumar Sanghvi <divinekumar@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 027c7ff..a46c64e 100644 (file)
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -111,6 +111,14 @@ int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt
            ipv6_addr_loopback(&hdr->daddr))
                goto err;
 
+       /*
+        * RFC4291 2.7
+        * Multicast addresses must not be used as source addresses in IPv6
+        * packets or appear in any Routing header.
+        */
+       if (ipv6_addr_is_multicast(&hdr->saddr))
+               goto err;
+
        skb->transport_header = skb->network_header + sizeof(*hdr);
        IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);