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Commit 76ba0aae authored by Tom Herbert's avatar Tom Herbert Committed by David S. Miller
Browse files

net: Generalize checksum_init functions 



Create a general __skb_checksum_validate function (actually a
macro) to subsume the various checksum_init functions. This
function can either init the checksum, or do the full validation
(logically checksum_init+skb_check_complete)-- a flag specifies
if full vaidation is performed. Also, there is a flag to the function
to indicate that zero checksums are allowed (to support optional
UDP checksums).

Added several stub functions for calling __skb_checksum_validate.

Signed-off-by: default avatarTom Herbert <therbert@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 20fce54f

include/linux/skbuff.h

+93 −0
Original line number Diff line number Diff line
@@ -2741,6 +2741,99 @@ static inline __sum16 skb_checksum_complete(struct sk_buff *skb) 
	       0 : __skb_checksum_complete(skb);

}



/* Check if we need to perform checksum complete validation.

 *

 * Returns true if checksum complete is needed, false otherwise

 * (either checksum is unnecessary or zero checksum is allowed).

 */

static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,

						  bool zero_okay,

						  __sum16 check)

{

	if (skb_csum_unnecessary(skb)) {

		return false;

	} else if (zero_okay && !check) {

		skb->ip_summed = CHECKSUM_UNNECESSARY;

		return false;

	}



	return true;

}



/* For small packets <= CHECKSUM_BREAK peform checksum complete directly

 * in checksum_init.

 */

#define CHECKSUM_BREAK 76



/* Validate (init) checksum based on checksum complete.

 *

 * Return values:

 *   0: checksum is validated or try to in skb_checksum_complete. In the latter

 *	case the ip_summed will not be CHECKSUM_UNNECESSARY and the pseudo

 *	checksum is stored in skb->csum for use in __skb_checksum_complete

 *   non-zero: value of invalid checksum

 *

 */

static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,

						       bool complete,

						       __wsum psum)

{

	if (skb->ip_summed == CHECKSUM_COMPLETE) {

		if (!csum_fold(csum_add(psum, skb->csum))) {

			skb->ip_summed = CHECKSUM_UNNECESSARY;

			return 0;

		}

	}



	skb->csum = psum;



	if (complete || skb->len <= CHECKSUM_BREAK)

		return __skb_checksum_complete(skb);



	return 0;

}



static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)

{

	return 0;

}



/* Perform checksum validate (init). Note that this is a macro since we only

 * want to calculate the pseudo header which is an input function if necessary.

 * First we try to validate without any computation (checksum unnecessary) and

 * then calculate based on checksum complete calling the function to compute

 * pseudo header.

 *

 * Return values:

 *   0: checksum is validated or try to in skb_checksum_complete

 *   non-zero: value of invalid checksum

 */

#define __skb_checksum_validate(skb, proto, complete,			\

				zero_okay, check, compute_pseudo)	\

({									\

	__sum16 __ret = 0;						\

	if (__skb_checksum_validate_needed(skb, zero_okay, check))	\

		__ret = __skb_checksum_validate_complete(skb,		\

				complete, compute_pseudo(skb, proto));	\

	__ret;								\

})



#define skb_checksum_init(skb, proto, compute_pseudo)			\

	__skb_checksum_validate(skb, proto, false, false, 0, compute_pseudo)



#define skb_checksum_init_zero_check(skb, proto, check, compute_pseudo)	\

	__skb_checksum_validate(skb, proto, false, true, check, compute_pseudo)



#define skb_checksum_validate(skb, proto, compute_pseudo)		\

	__skb_checksum_validate(skb, proto, true, false, 0, compute_pseudo)



#define skb_checksum_validate_zero_check(skb, proto, check,		\

					 compute_pseudo)		\

	__skb_checksum_validate_(skb, proto, true, true, check, compute_pseudo)



#define skb_checksum_simple_validate(skb)				\

	__skb_checksum_validate(skb, 0, true, false, 0, null_compute_pseudo)



#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)

void nf_conntrack_destroy(struct nf_conntrack *nfct);

static inline void nf_conntrack_put(struct nf_conntrack *nfct)