Subject: [PATCH] netfilter: flowtable: refresh timeout after dst and writable checks
From: Pablo Neira Ayuso <[email-masked]>
Date: Tue, 23 Mar 2021 00:56:27 +0100

Refresh the timeout (and retry hardware offload) once the skbuff dst
is confirmed to be current and after the skbuff is made writable.

Signed-off-by: Pablo Neira Ayuso <[email-masked]>
---

--- a/net/netfilter/nf_flow_table_ip.c
+++ b/net/netfilter/nf_flow_table_ip.c
@@ -246,8 +246,6 @@ nf_flow_offload_ip_hook(void *priv, stru
 	if (nf_flow_state_check(flow, iph->protocol, skb, thoff))
 		return NF_ACCEPT;
 
-	flow_offload_refresh(flow_table, flow);
-
 	if (!dst_check(&rt->dst, 0)) {
 		flow_offload_teardown(flow);
 		return NF_ACCEPT;
@@ -256,6 +254,8 @@ nf_flow_offload_ip_hook(void *priv, stru
 	if (skb_try_make_writable(skb, thoff + hdrsize))
 		return NF_DROP;
 
+	flow_offload_refresh(flow_table, flow);
+
 	iph = ip_hdr(skb);
 	nf_flow_nat_ip(flow, skb, thoff, dir, iph);
 
@@ -466,8 +466,6 @@ nf_flow_offload_ipv6_hook(void *priv, st
 				sizeof(*ip6h)))
 		return NF_ACCEPT;
 
-	flow_offload_refresh(flow_table, flow);
-
 	if (!dst_check(&rt->dst, 0)) {
 		flow_offload_teardown(flow);
 		return NF_ACCEPT;
@@ -476,6 +474,8 @@ nf_flow_offload_ipv6_hook(void *priv, st
 	if (skb_try_make_writable(skb, sizeof(*ip6h) + hdrsize))
 		return NF_DROP;
 
+	flow_offload_refresh(flow_table, flow);
+
 	ip6h = ipv6_hdr(skb);
 	nf_flow_nat_ipv6(flow, skb, dir, ip6h);