net: Save software checksum complete

In skb_checksum complete, if we need to compute the checksum for the
packet (via skb_checksum) save the result as CHECKSUM_COMPLETE.
Subsequent checksum verification can use this.

Also, added csum_complete_sw flag to distinguish between software and
hardware generated checksum complete, we should always be able to trust
the software computation.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 2 deletions

diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
index 24deb3928b9e..eb92deb12666 100644
--- a/net/ipv4/gre_offload.c
+++ b/net/ipv4/gre_offload.c
@@ -131,10 +131,12 @@ static __sum16 gro_skb_checksum(struct sk_buff *skb)
                 csum_partial(skb->data, skb_gro_offset(skb), 0));
         sum = csum_fold(NAPI_GRO_CB(skb)->csum);
         if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) {
-                if (unlikely(!sum))
+                if (unlikely(!sum) && !skb->csum_complete_sw)
                         netdev_rx_csum_fault(skb->dev);
-        } else
+        } else {
                 skb->ip_summed = CHECKSUM_COMPLETE;
+                skb->csum_complete_sw = 1;
+        }
 
         return sum;
 }