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Commit 018c5bba authored by David S. Miller's avatar David S. Miller
Browse files

net: Handle CHECKSUM_COMPLETE more adequately in pskb_trim_rcsum(). 



Currently pskb_trim_rcsum() just balks on CHECKSUM_COMPLETE packets
and remarks them as CHECKSUM_NONE, forcing a software checksum
validation later.

We have all of the mechanics available to fixup the skb->csum value,
even for complicated fragmented packets, via the helpers
skb_checksum() and csum_sub().

So just use them.

Based upon a suggestion by Herbert Xu.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f52ed899

include/linux/skbuff.h

+21 −18
Original line number Diff line number Diff line
@@ -2263,24 +2263,6 @@ static inline void skb_postpull_rcsum(struct sk_buff *skb, 


unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);



/**

 *	pskb_trim_rcsum - trim received skb and update checksum

 *	@skb: buffer to trim

 *	@len: new length

 *

 *	This is exactly the same as pskb_trim except that it ensures the

 *	checksum of received packets are still valid after the operation.

 */



static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)

{

	if (likely(len >= skb->len))

		return 0;

	if (skb->ip_summed == CHECKSUM_COMPLETE)

		skb->ip_summed = CHECKSUM_NONE;

	return __pskb_trim(skb, len);

}



#define skb_queue_walk(queue, skb) \

		for (skb = (queue)->next;					\

		     skb != (struct sk_buff *)(queue);				\
@@ -2378,6 +2360,27 @@ __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len, 
__wsum skb_checksum(const struct sk_buff *skb, int offset, int len,

		    __wsum csum);



/**

 *	pskb_trim_rcsum - trim received skb and update checksum

 *	@skb: buffer to trim

 *	@len: new length

 *

 *	This is exactly the same as pskb_trim except that it ensures the

 *	checksum of received packets are still valid after the operation.

 */



static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)

{

	if (likely(len >= skb->len))

		return 0;

	if (skb->ip_summed == CHECKSUM_COMPLETE) {

		__wsum adj = skb_checksum(skb, len, skb->len - len, 0);



		skb->csum = csum_sub(skb->csum, adj);

	}

	return __pskb_trim(skb, len);

}



static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,

				       int len, void *buffer)

{