netfilter: ebt_ip6: fix source and destination matching

This bug was introduced on commit 0898f99. This just recovers two
checks that existed before as suggested by Bart De Schuymer.

Signed-off-by: Luís Fernando Cornachioni Estrozi <lestrozi@uolinc.com>
Signed-off-by: Bart De Schuymer <bdschuym@pandora.be>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/bridge/netfilter/ebt_ip6.c

@@ -48,10 +48,12 @@ ebt_ip6_mt(const struct sk_buff *skb, struct xt_action_param *par)
 	if (info->bitmask & EBT_IP6_TCLASS &&
 	   FWINV(info->tclass != ipv6_get_dsfield(ih6), EBT_IP6_TCLASS))
 		return false;
-	if (FWINV(ipv6_masked_addr_cmp(&ih6->saddr, &info->smsk,
-				       &info->saddr), EBT_IP6_SOURCE) ||
+	if ((info->bitmask & EBT_IP6_SOURCE &&
+	    FWINV(ipv6_masked_addr_cmp(&ih6->saddr, &info->smsk,
+				       &info->saddr), EBT_IP6_SOURCE)) ||
+	    (info->bitmask & EBT_IP6_DEST &&
 	    FWINV(ipv6_masked_addr_cmp(&ih6->daddr, &info->dmsk,
-				       &info->daddr), EBT_IP6_DEST))
+				       &info->daddr), EBT_IP6_DEST)))
 		return false;
 	if (info->bitmask & EBT_IP6_PROTO) {
 		uint8_t nexthdr = ih6->nexthdr;