[NET]: Detect hardware rx checksum faults correctly

Here is the patch that introduces the generic skb_checksum_complete
which also checks for hardware RX checksum faults.  If that happens,
it'll call netdev_rx_csum_fault which currently prints out a stack
trace with the device name.  In future it can turn off RX checksum.

I've converted every spot under net/ that does RX checksum checks to
use skb_checksum_complete or __skb_checksum_complete with the
exceptions of:

* Those places where checksums are done bit by bit.  These will call
netdev_rx_csum_fault directly.

* The following have not been completely checked/converted:

ipmr
ip_vs
netfilter
dccp

This patch is based on patches and suggestions from Stephen Hemminger
and David S. Miller.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 5 deletions

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index c6247fc84060..c04607b49212 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -872,11 +872,18 @@ int igmp_rcv(struct sk_buff *skb)
                 return 0;
         }
 
-        if (!pskb_may_pull(skb, sizeof(struct igmphdr)) || 
-            (u16)csum_fold(skb_checksum(skb, 0, len, 0))) {
-                in_dev_put(in_dev);
-                kfree_skb(skb);
-                return 0;
+        if (!pskb_may_pull(skb, sizeof(struct igmphdr)))
+                goto drop;
+
+        switch (skb->ip_summed) {
+        case CHECKSUM_HW:
+                if (!(u16)csum_fold(skb->csum))
+                        break;
+                /* fall through */
+        case CHECKSUM_NONE:
+                skb->csum = 0;
+                if (__skb_checksum_complete(skb))
+                        goto drop;
         }
 
         ih = skb->h.igmph;
@@ -906,6 +913,8 @@ int igmp_rcv(struct sk_buff *skb)
         default:
                 NETDEBUG(KERN_DEBUG "New IGMP type=%d, why we do not know about it?\n", ih->type);
         }
+
+drop:
         in_dev_put(in_dev);
         kfree_skb(skb);
         return 0;