netfilter: nf_conncount: Fix garbage collection with zones

BugLink: https://bugs.launchpad.net/bugs/1811094

Currently, we use check_hlist() for garbage colleciton. However, we
use the ‘zone’ from the counted entry to query the existence of
existing entries in the hlist. This could be wrong when they are in
different zones, and this patch fixes this issue.

Fixes: e59ea3df ("netfilter: xt_connlimit: honor conntrack zone if available")
Signed-off-by: Yi-Hung Wei <yihung.wei@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
(backported from commit 21ba8847)
[mfo: backport: refresh context lines and use older symbol/file names, note hunk 5:
 - nf_conncount.c -> xt_connlimit.c
   - nf_conncount_rb -> xt_connlimit_rb
   - nf_conncount_tuple -> xt_connlimit_conn
   - hunk 5: remove check for non-NULL 'tuple', that isn't required as it's introduced
     by upstream commit 35d8deb8 ("netfilter: conncount: Support count only use case")
     which addresses nf_conncount_count() that does not exist yet -- it's introduced by
     upstream commit 625c5561 ("netfilter: connlimit: split xt_connlimit into front
     and backend"), a refactor change.
 - nft_connlimit.c -> removed, not used/doesn't exist yet.]
Signed-off-by: Mauricio Faria de Oliveira <mfo@canonical.com>
Acked-by: Khalid Elmously <khalid.elmously@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

include/net/netfilter/nf_conntrack_count.h

@@ -7,7 +7,8 @@ unsigned int nf_conncount_lookup(struct net *net, struct hlist_head *head,
 				 bool *addit);
 
 bool nf_conncount_add(struct hlist_head *head,
-		      const struct nf_conntrack_tuple *tuple);
+		      const struct nf_conntrack_tuple *tuple,
+		      const struct nf_conntrack_zone *zone);
 
 void nf_conncount_cache_free(struct hlist_head *hhead);
 

net/netfilter/xt_connlimit.c

@@ -46,6 +46,7 @@
 struct xt_connlimit_conn {
 	struct hlist_node		node;
 	struct nf_conntrack_tuple	tuple;
+	struct nf_conntrack_zone	zone;
 };
 
 struct xt_connlimit_rb {
@@ -116,7 +117,8 @@ same_source_net(const union nf_inet_addr *addr,
 }
 
 bool nf_conncount_add(struct hlist_head *head,
-		      const struct nf_conntrack_tuple *tuple)
+		      const struct nf_conntrack_tuple *tuple,
+		      const struct nf_conntrack_zone *zone)
 {
 	struct xt_connlimit_conn *conn;
 
@@ -124,6 +126,7 @@ bool nf_conncount_add(struct hlist_head *head,
 	if (conn == NULL)
 		return false;
 	conn->tuple = *tuple;
+	conn->zone = *zone;
 	hlist_add_head(&conn->node, head);
 	return true;
 }
@@ -145,7 +148,7 @@ unsigned int nf_conncount_lookup(struct net *net, struct hlist_head *head,
 
 	/* check the saved connections */
 	hlist_for_each_entry_safe(conn, n, head, node) {
-		found = nf_conntrack_find_get(net, zone, &conn->tuple);
+		found = nf_conntrack_find_get(net, &conn->zone, &conn->tuple);
 		if (found == NULL) {
 			hlist_del(&conn->node);
 			kmem_cache_free(connlimit_conn_cachep, conn);
@@ -154,7 +157,8 @@ unsigned int nf_conncount_lookup(struct net *net, struct hlist_head *head,
 
 		found_ct = nf_ct_tuplehash_to_ctrack(found);
 
-		if (nf_ct_tuple_equal(&conn->tuple, tuple)) {
+		if (nf_ct_tuple_equal(&conn->tuple, tuple) &&
+		    nf_ct_zone_equal(found_ct, zone, zone->dir)) {
 			/*
 			 * Just to be sure we have it only once in the list.
 			 * We should not see tuples twice unless someone hooks
@@ -235,7 +239,7 @@ count_tree(struct net *net, struct rb_root *root,
 			if (!addit)
 				return count;
 
-			if (!nf_conncount_add(&rbconn->hhead, tuple))
+			if (!nf_conncount_add(&rbconn->hhead, tuple, zone))
 				return 0; /* hotdrop */
 
 			return count + 1;
@@ -274,6 +278,7 @@ count_tree(struct net *net, struct rb_root *root,
 	}
 
 	conn->tuple = *tuple;
+	conn->zone = *zone;
 	rbconn->addr = *addr;
 
 	INIT_HLIST_HEAD(&rbconn->hhead);