netdev - [PATCH net 3/3] netfilter: ctnetlink: remove expired entries first

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Date:   Fri, 17 Dec 2021 09:53:03 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org
Subject: [PATCH net 3/3] netfilter: ctnetlink: remove expired entries first

From: Florian Westphal <fw@...len.de>

When dumping conntrack table to userspace via ctnetlink, check if the ct has
already expired before doing any of the 'skip' checks.

This expires dead entries faster.
/proc handler also removes outdated entries first.

Reported-by: Vitaly Zuevsky <vzuevsky@....com>
Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nf_conntrack_netlink.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 81d03acf68d4..ec4164c32d27 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -1195,8 +1195,6 @@ ctnetlink_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
 		}
 		hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[cb->args[0]],
 					   hnnode) {
-			if (NF_CT_DIRECTION(h) != IP_CT_DIR_ORIGINAL)
-				continue;
 			ct = nf_ct_tuplehash_to_ctrack(h);
 			if (nf_ct_is_expired(ct)) {
 				if (i < ARRAY_SIZE(nf_ct_evict) &&
@@ -1208,6 +1206,9 @@ ctnetlink_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
 			if (!net_eq(net, nf_ct_net(ct)))
 				continue;
 
+			if (NF_CT_DIRECTION(h) != IP_CT_DIR_ORIGINAL)
+				continue;
+
 			if (cb->args[1]) {
 				if (ct != last)
 					continue;
-- 
2.30.2