net/ipv6: Increment OUTxxx counters after netfilter hook

At the end of ip6_forward(), IPSTATS_MIB_OUTFORWDATAGRAMS and IPSTATS_MIB_OUTOCTETS are incremented immediately before the NF_HOOK call for NFPROTO_IPV6 / NF_INET_FORWARD. As a result, these counters get incremented regardless of whether or not the netfilter hook allows the packet to continue being processed. This change increments the counters in ip6_forward_finish() so that it will not happen if the netfilter hook chooses to terminate the packet, which is similar to how IPv4 works.

---
 net/ipv6/ip6_output.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

index b8ee50e94af3..2e891d2c30ef 100644
@@ -375,6 +375,11 @@ static int ip6_forward_proxy_check(struct sk_buff *skb)
 static inline int ip6_forward_finish(struct net *net, struct sock *sk,
 				     struct sk_buff *skb)
 {
+	struct dst_entry *dst = skb_dst(skb);
+
+	__IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTFORWDATAGRAMS);
+	__IP6_ADD_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTOCTETS, skb->len);
+
 	return dst_output(net, sk, skb);
 }
 

@@ -569,8 +574,6 @@ int ip6_forward(struct sk_buff *skb)
 
 	hdr->hop_limit--;
 
-	__IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTFORWDATAGRAMS);
-	__IP6_ADD_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTOCTETS, skb->len);
 	return NF_HOOK(NFPROTO_IPV6, NF_INET_FORWARD,
 		       net, NULL, skb, skb->dev, dst->dev,
 		       ip6_forward_finish);

2.14.1

From: Jeff Barnhill <[email protected]>
Date: Thu, 5 Apr 2018 21:29:47 +0000

Yep, this is more consistent with ipv4.

Applied, thank you.

Hi,

[This is an automated email]

This commit has been processed by the -stable helper bot and determined to be a high probability candidate for -stable trees. (score: 5.8567)

The bot has tested the following trees: v4.16.1, v4.15.16, v4.14.33, v4.9.93, v4.4.127.

v4.16.1: Build OK!
v4.15.16: Build OK!
v4.14.33: Build OK!
v4.9.93: Build OK!
v4.4.127: Failed to apply! Possible dependencies:

    1d0155035918 ("ipv6: rename IP6_INC_STATS_BH()")

Please let us know if you'd like to have this patch included in a stable tree.