[NETFILTER]: Avoid unncessary checksum validation in UDP connection tracking

Signed-off-by: Keir Fraser <Keir.Fraser@xl.cam.ac.uk>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/net/ipv4/netfilter/ip_conntrack_proto_udp.c b/net/ipv4/netfilter/ip_conntrack_proto_udp.c
index 5bc28a224623..8c1eaba098d4 100644
--- a/net/ipv4/netfilter/ip_conntrack_proto_udp.c
+++ b/net/ipv4/netfilter/ip_conntrack_proto_udp.c
@@ -120,6 +120,7 @@ static int udp_error(struct sk_buff *skb, enum ip_conntrack_info *ctinfo,
          * and moreover root might send raw packets.
          * FIXME: Source route IP option packets --RR */
         if (hooknum == NF_IP_PRE_ROUTING
+            && skb->ip_summed != CHECKSUM_UNNECESSARY
             && csum_tcpudp_magic(iph->saddr, iph->daddr, udplen, IPPROTO_UDP,
                                  skb->ip_summed == CHECKSUM_HW ? skb->csum
                                  : skb_checksum(skb, iph->ihl*4, udplen, 0))) {