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net: Fix save software checksum complete

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Geert reported issues regarding checksum complete and UDP.
The logic introduced in commit 7e3cead517
("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>
This commit is contained in:
Tom Herbert 2014-06-14 23:24:03 -07:00 committed by David S. Miller
parent 4b28252cad
commit 46fb51eb96
2 changed files with 29 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
net/core/datagram.c
View File

@ -739,22 +739,38 @@ __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
__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);

3
net/core/skbuff.c
View File

@ -689,6 +689,9 @@ static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
new->ooo_okay = old->ooo_okay;
new->no_fcs = old->no_fcs;
new->encapsulation = old->encapsulation;
new->encap_hdr_csum = old->encap_hdr_csum;
new->csum_valid = old->csum_valid;
new->csum_complete_sw = old->csum_complete_sw;
#ifdef CONFIG_XFRM
new->sp = secpath_get(old->sp);
#endif