netfilter: ipset: forbid family for hash:mac sets

Userspace `ipset` command forbids family option for hash:mac type:

ipset create test hash:mac family inet4
ipset v6.30: Unknown argument: `family'

However, this check is not done in kernel itself. When someone use
external netlink applications (pyroute2 python library for example), one
can create hash:mac with invalid family and inconsistant results from
userspace (`ipset` command cannot read set content anymore).

This patch enforce the logic in kernel, and forbids insertion of
hash:mac with a family set.

Since IP_SET_PROTO_UNDEF is defined only for hash:mac, this patch has no
impact on other hash:* sets

Signed-off-by: Florent Fourcot <florent.fourcot@wifirst.fr>
Signed-off-by: Victorien Molle <victorien.molle@wifirst.fr>
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>

net/netfilter/ipset/ip_set_hash_gen.h

@@ -1234,7 +1234,10 @@ IPSET_TOKEN(HTYPE, _create)(struct net *net, struct ip_set *set,
 	pr_debug("Create set %s with family %s\n",
 		 set->name, set->family == NFPROTO_IPV4 ? "inet" : "inet6");
 
-#ifndef IP_SET_PROTO_UNDEF
+#ifdef IP_SET_PROTO_UNDEF
+	if (set->family != NFPROTO_UNSPEC)
+		return -IPSET_ERR_INVALID_FAMILY;
+#else
 	if (!(set->family == NFPROTO_IPV4 || set->family == NFPROTO_IPV6))
 		return -IPSET_ERR_INVALID_FAMILY;
 #endif