netfilter: xtables: do centralized checkentry call (1/2)

It used to be that {ip,ip6,etc}_tables called extension->checkentry
themselves, but this can be moved into the xtables core.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 4e7c719..b4c74a7 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -616,17 +616,14 @@
 	match = m->u.kernel.match;
 	ret = xt_check_match(match, AF_INET, m->u.match_size - sizeof(*m),
 			     name, hookmask, ip->proto,
-			     ip->invflags & IPT_INV_PROTO);
-	if (!ret && m->u.kernel.match->checkentry
-	    && !m->u.kernel.match->checkentry(name, ip, match, m->data,
-					      hookmask)) {
+			     ip->invflags & IPT_INV_PROTO, ip, m->data);
+	if (ret < 0) {
 		duprintf("ip_tables: check failed for `%s'.\n",
 			 m->u.kernel.match->name);
-		ret = -EINVAL;
+		return ret;
 	}
-	if (!ret)
-		(*i)++;
-	return ret;
+	++*i;
+	return 0;
 }
 
 static int
@@ -668,15 +665,13 @@
 	target = t->u.kernel.target;
 	ret = xt_check_target(target, AF_INET, t->u.target_size - sizeof(*t),
 			      name, e->comefrom, e->ip.proto,
-			      e->ip.invflags & IPT_INV_PROTO);
-	if (!ret && t->u.kernel.target->checkentry
-	    && !t->u.kernel.target->checkentry(name, e, target, t->data,
-					       e->comefrom)) {
+			      e->ip.invflags & IPT_INV_PROTO, e, t->data);
+	if (ret < 0) {
 		duprintf("ip_tables: check failed for `%s'.\n",
 			 t->u.kernel.target->name);
-		ret = -EINVAL;
+		return ret;
 	}
-	return ret;
+	return 0;
 }
 
 static int