snmp: fix OutOctets counter to include forwarded datagrams

RFC 4293 defines ipIfStatsOutOctets (similar definition for
ipSystemStatsOutOctets):

   The total number of octets in IP datagrams delivered to the lower
   layers for transmission.  Octets from datagrams counted in
   ipIfStatsOutTransmits MUST be counted here.

And ipIfStatsOutTransmits:

   The total number of IP datagrams that this entity supplied to the
   lower layers for transmission.  This includes datagrams generated
   locally and those forwarded by this entity.

Therefore, IPSTATS_MIB_OUTOCTETS must be incremented when incrementing
IPSTATS_MIB_OUTFORWDATAGRAMS.

IP_UPD_PO_STATS is not used since ipIfStatsOutRequests must not
include forwarded datagrams:

   The total number of IP datagrams that local IP user-protocols
   (including ICMP) supplied to IP in requests for transmission.  Note
   that this counter does not include any datagrams counted in
   ipIfStatsOutForwDatagrams.

Signed-off-by: Vincent Bernat <bernat@luffy.cx>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
index e5c44fc586ab..ab09b126423c 100644
--- a/net/ipv4/ip_forward.c
+++ b/net/ipv4/ip_forward.c
@@ -44,6 +44,7 @@ static int ip_forward_finish(struct sk_buff *skb)
         struct ip_options *opt  = &(IPCB(skb)->opt);
 
         IP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), IPSTATS_MIB_OUTFORWDATAGRAMS);
+        IP_ADD_STATS_BH(dev_net(skb_dst(skb)->dev), IPSTATS_MIB_OUTOCTETS, skb->len);
 
         if (unlikely(opt->optlen))
                 ip_forward_options(skb);