netfilter: ipset: allow a 0 netmask with hash_netiface type

Jozsef says:
 The correct behaviour is that if we have
 ipset create test1 hash:net,iface
 ipset add test1 0.0.0.0/0,eth0
 iptables -A INPUT -m set --match-set test1 src,src

 then the rule should match for any traffic coming in through eth0.

This removes the -EINVAL runtime test to make matching work
in case packet arrived via the specified interface.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1297092
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/ipset/ip_set_hash_netiface.c

@@ -164,8 +164,6 @@ hash_netiface4_kadt(struct ip_set *set, const struct sk_buff *skb,
 	};
 	struct ip_set_ext ext = IP_SET_INIT_KEXT(skb, opt, set);
 
-	if (e.cidr == 0)
-		return -EINVAL;
 	if (adt == IPSET_TEST)
 		e.cidr = HOST_MASK;
 
@@ -377,8 +375,6 @@ hash_netiface6_kadt(struct ip_set *set, const struct sk_buff *skb,
 	};
 	struct ip_set_ext ext = IP_SET_INIT_KEXT(skb, opt, set);
 
-	if (e.cidr == 0)
-		return -EINVAL;
 	if (adt == IPSET_TEST)
 		e.cidr = HOST_MASK;