net: Fix save software checksum complete
Geert reported issues regarding checksum complete and UDP.
The logic introduced in commit 7e3cead5172927732f51fde
("net: Save software checksum complete") is not correct.
This patch:
1) Restores code in __skb_checksum_complete_header except for setting
CHECKSUM_UNNECESSARY. This function may be calculating checksum on
something less than skb->len.
2) Adds saving checksum to __skb_checksum_complete. The full packet
checksum 0..skb->len is calculated without adding in pseudo header.
This value is saved in skb->csum and then the pseudo header is added
to that to derive the checksum for validation.
3) In both __skb_checksum_complete_header and __skb_checksum_complete,
set skb->csum_valid to whether checksum of zero was computed. This
allows skb_csum_unnecessary to return true without changing to
CHECKSUM_UNNECESSARY which was done previously.
4) Copy new csum related bits in __copy_skb_header.
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/datagram.c b/net/core/datagram.c
index 6b1c04c..488dd1a 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -739,22 +739,38 @@
__sum16 sum;
sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
- if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) && !sum &&
- !skb->csum_complete_sw)
- netdev_rx_csum_fault(skb->dev);
-
- /* Save checksum complete for later use */
- skb->csum = sum;
- skb->ip_summed = CHECKSUM_COMPLETE;
- skb->csum_complete_sw = 1;
-
+ if (likely(!sum)) {
+ if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
+ !skb->csum_complete_sw)
+ netdev_rx_csum_fault(skb->dev);
+ }
+ skb->csum_valid = !sum;
return sum;
}
EXPORT_SYMBOL(__skb_checksum_complete_head);
__sum16 __skb_checksum_complete(struct sk_buff *skb)
{
- return __skb_checksum_complete_head(skb, skb->len);
+ __wsum csum;
+ __sum16 sum;
+
+ csum = skb_checksum(skb, 0, skb->len, 0);
+
+ /* skb->csum holds pseudo checksum */
+ sum = csum_fold(csum_add(skb->csum, csum));
+ if (likely(!sum)) {
+ if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
+ !skb->csum_complete_sw)
+ netdev_rx_csum_fault(skb->dev);
+ }
+
+ /* Save full packet checksum */
+ skb->csum = csum;
+ skb->ip_summed = CHECKSUM_COMPLETE;
+ skb->csum_complete_sw = 1;
+ skb->csum_valid = !sum;
+
+ return sum;
}
EXPORT_SYMBOL(__skb_checksum_complete);