[SRU T][PATCH 1/3] netfilter: connlimit: improve packet-to-closed-connection logic

[Mauricio Faria de Oliveira]

From: Florian Westphal <fw at strlen.de>

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

Instead of freeing the entry from our list and then adding
it back again in the 'packet to closing connection' case just keep the
matching entry around.  Also drop the found_ct != NULL test as
nf_ct_tuplehash_to_ctrack is just container_of().

Reviewed-by: Jesper Dangaard Brouer <brouer at redhat.com>
Signed-off-by: Florian Westphal <fw at strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>
(backported from commit d9ec4f1ee280e5f8732e3c40ca672419b2532600)
[mfo: backport: s/head/hash/ in the hlist_for_each_entry_safe() call
 due to lack of commit 15cfd5289575 ("netfilter: connlimit: factor
 hlist search into new function")]
Signed-off-by: Mauricio Faria de Oliveira <mfo at canonical.com>
---
 net/netfilter/xt_connlimit.c | 23 ++++++++---------------
 1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/net/netfilter/xt_connlimit.c b/net/netfilter/xt_connlimit.c
index c40b2695633b..5d18f39ad69b 100644
--- a/net/netfilter/xt_connlimit.c
+++ b/net/netfilter/xt_connlimit.c
@@ -118,29 +118,22 @@ static int count_them(struct net *net,
 	hlist_for_each_entry_safe(conn, n, hash, node) {
 		found    = nf_conntrack_find_get(net, NF_CT_DEFAULT_ZONE,
 						 &conn->tuple);
-		found_ct = NULL;
+		if (found == NULL) {
+			hlist_del(&conn->node);
+			kfree(conn);
+			continue;
+		}
 
-		if (found != NULL)
-			found_ct = nf_ct_tuplehash_to_ctrack(found);
+		found_ct = nf_ct_tuplehash_to_ctrack(found);
 
-		if (found_ct != NULL &&
-		    nf_ct_tuple_equal(&conn->tuple, tuple) &&
-		    !already_closed(found_ct))
+		if (nf_ct_tuple_equal(&conn->tuple, tuple)) {
 			/*
 			 * Just to be sure we have it only once in the list.
 			 * We should not see tuples twice unless someone hooks
 			 * this into a table without "-p tcp --syn".
 			 */
 			addit = false;
-
-		if (found == NULL) {
-			/* this one is gone */
-			hlist_del(&conn->node);
-			kfree(conn);
-			continue;
-		}
-
-		if (already_closed(found_ct)) {
+		} else if (already_closed(found_ct)) {
 			/*
 			 * we do not care about connections which are
 			 * closed already -> ditch it
-- 
2.17.1