netfilter: xtables: fix IPv6 dependency in the cluster match

This patch fixes a dependency with IPv6:

ERROR: "__ipv6_addr_type" [net/netfilter/xt_cluster.ko] undefined!

This patch adds a function that checks if the higher bits of the
address is 0xFF to identify a multicast address, instead of adding a
dependency due to __ipv6_addr_type(). I came up with this idea after
Patrick McHardy pointed possible problems with runtime module
dependencies.

Reported-by: Steven Noonan <steven@uplinklabs.net>
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Reported-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 2 deletions

diff --git a/net/netfilter/xt_cluster.c b/net/netfilter/xt_cluster.c
index ad5bd890e4e8..6c4847662b85 100644
--- a/net/netfilter/xt_cluster.c
+++ b/net/netfilter/xt_cluster.c
@@ -58,6 +58,13 @@ xt_cluster_hash(const struct nf_conn *ct,
 }
 
 static inline bool
+xt_cluster_ipv6_is_multicast(const struct in6_addr *addr)
+{
+        __be32 st = addr->s6_addr32[0];
+        return ((st & htonl(0xFF000000)) == htonl(0xFF000000));
+}
+
+static inline bool
 xt_cluster_is_multicast_addr(const struct sk_buff *skb, u_int8_t family)
 {
         bool is_multicast = false;
@@ -67,8 +74,8 @@ xt_cluster_is_multicast_addr(const struct sk_buff *skb, u_int8_t family)
                 is_multicast = ipv4_is_multicast(ip_hdr(skb)->daddr);
                 break;
         case NFPROTO_IPV6:
-                is_multicast = ipv6_addr_type(&ipv6_hdr(skb)->daddr) &
-                                                IPV6_ADDR_MULTICAST;
+                is_multicast =
+                        xt_cluster_ipv6_is_multicast(&ipv6_hdr(skb)->daddr);
                 break;
         default:
                 WARN_ON(1);