ipv6: Fix MLD Query message check

Based on RFC3810 6.2, we also need to check the hop limit and router alert
option besides source address.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Acked-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 2 deletions

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 08b367c6b9cf..617f0958e164 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1301,8 +1301,17 @@ int igmp6_event_query(struct sk_buff *skb)
         len = ntohs(ipv6_hdr(skb)->payload_len) + sizeof(struct ipv6hdr);
         len -= skb_network_header_len(skb);
 
-        /* Drop queries with not link local source */
-        if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL))
+        /* RFC3810 6.2
+         * Upon reception of an MLD message that contains a Query, the node
+         * checks if the source address of the message is a valid link-local
+         * address, if the Hop Limit is set to 1, and if the Router Alert
+         * option is present in the Hop-By-Hop Options header of the IPv6
+         * packet.  If any of these checks fails, the packet is dropped.
+         */
+        if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL) ||
+            ipv6_hdr(skb)->hop_limit != 1 ||
+            !(IP6CB(skb)->flags & IP6SKB_ROUTERALERT) ||
+            IP6CB(skb)->ra != htons(IPV6_OPT_ROUTERALERT_MLD))
                 return -EINVAL;
 
         idev = __in6_dev_get(skb->dev);