netfilter: ipset: Support updating extensions when the set is full

When the set was full (hash type and maxelem reached), it was not
possible to update the extension part of already existing elements.
The patch removes this limitation.

Fixes: https://bugzilla.netfilter.org/show_bug.cgi?id=880
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/ipset/ip_set_hash_gen.h

@@ -633,29 +633,6 @@ mtype_add(struct ip_set *set, void *value, const struct ip_set_ext *ext,
 	bool flag_exist = flags & IPSET_FLAG_EXIST;
 	u32 key, multi = 0;
 
-	if (h->elements >= h->maxelem && SET_WITH_FORCEADD(set)) {
-		rcu_read_lock_bh();
-		t = rcu_dereference_bh(h->table);
-		key = HKEY(value, h->initval, t->htable_bits);
-		n = hbucket(t,key);
-		if (n->pos) {
-			/* Choosing the first entry in the array to replace */
-			j = 0;
-			goto reuse_slot;
-		}
-		rcu_read_unlock_bh();
-	}
-	if (SET_WITH_TIMEOUT(set) && h->elements >= h->maxelem)
-		/* FIXME: when set is full, we slow down here */
-		mtype_expire(set, h, NLEN(set->family), set->dsize);
-
-	if (h->elements >= h->maxelem) {
-		if (net_ratelimit())
-			pr_warn("Set %s is full, maxelem %u reached\n",
-				set->name, h->maxelem);
-		return -IPSET_ERR_HASH_FULL;
-	}
-
 	rcu_read_lock_bh();
 	t = rcu_dereference_bh(h->table);
 	key = HKEY(value, h->initval, t->htable_bits);
@@ -680,6 +657,23 @@ mtype_add(struct ip_set *set, void *value, const struct ip_set_ext *ext,
 		    j != AHASH_MAX(h) + 1)
 			j = i;
 	}
+	if (h->elements >= h->maxelem && SET_WITH_FORCEADD(set) && n->pos) {
+		/* Choosing the first entry in the array to replace */
+		j = 0;
+		goto reuse_slot;
+	}
+	if (SET_WITH_TIMEOUT(set) && h->elements >= h->maxelem)
+		/* FIXME: when set is full, we slow down here */
+		mtype_expire(set, h, NLEN(set->family), set->dsize);
+
+	if (h->elements >= h->maxelem) {
+		if (net_ratelimit())
+			pr_warn("Set %s is full, maxelem %u reached\n",
+				set->name, h->maxelem);
+		ret = -IPSET_ERR_HASH_FULL;
+		goto out;
+	}
+
 reuse_slot:
 	if (j != AHASH_MAX(h) + 1) {
 		/* Fill out reused slot */