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>

1 files changed, 8 insertions, 0 deletions

diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 027c7ff6f1e5..a46c64eb0a66 100644
--- 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);