netfilter: nf_ct_icmp: keep the ICMP ct entries longer

Current conntrack code kills the ICMP conntrack entry as soon as
the first reply is received. This is incorrect, as we then see only
the first ICMP echo reply out of several possible duplicates as
ESTABLISHED, while the rest will be INVALID. Also this unnecessarily
increases the conntrackd traffic on H-A firewalls.

Make all the ICMP conntrack entries (including the replied ones)
last for the default of nf_conntrack_icmp{,v6}_timeout seconds.

Signed-off-by: Jan "Yenya" Kasprzak <kas@fi.muni.cz>
Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 4 insertions, 12 deletions

diff --git a/net/ipv4/netfilter/nf_conntrack_proto_icmp.c b/net/ipv4/netfilter/nf_conntrack_proto_icmp.c
index c6ab3d99e792..d71ba7677344 100644
--- a/net/ipv4/netfilter/nf_conntrack_proto_icmp.c
+++ b/net/ipv4/netfilter/nf_conntrack_proto_icmp.c
@@ -82,17 +82,10 @@ static int icmp_packet(struct nf_conn *ct,
 		       u_int8_t pf,
 		       unsigned int hooknum)
 {
-	/* Try to delete connection immediately after all replies:
-	   won't actually vanish as we still have skb, and del_timer
-	   means this will only run once even if count hits zero twice
-	   (theoretically possible with SMP) */
-	if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
-		if (atomic_dec_and_test(&ct->proto.icmp.count))
-			nf_ct_kill_acct(ct, ctinfo, skb);
-	} else {
-		atomic_inc(&ct->proto.icmp.count);
-		nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout);
-	}
+	/* Do not immediately delete the connection after the first
+	   successful reply to avoid excessive conntrackd traffic
+	   and also to handle correctly ICMP echo reply duplicates. */
+	nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout);
 
 	return NF_ACCEPT;
 }
@@ -116,7 +109,6 @@ static bool icmp_new(struct nf_conn *ct, const struct sk_buff *skb,
 		nf_ct_dump_tuple_ip(&ct->tuplehash[0].tuple);
 		return false;
 	}
-	atomic_set(&ct->proto.icmp.count, 0);
 	return true;
 }