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Commit 5d0c2b95 authored by Tom Herbert's avatar Tom Herbert Committed by David S. Miller
Browse files

net: Preserve CHECKSUM_COMPLETE at validation 



Currently when the first checksum in a packet is validated using
CHECKSUM_COMPLETE, ip_summed is overwritten to be CHECKSUM_UNNECESSARY
so that any subsequent checksums in the packet are not correctly
validated.

This patch adds csum_valid flag in sk_buff and uses that to indicate
validated checksum instead of setting CHECKSUM_UNNECESSARY. The bit
is set accordingly in the skb_checksum_validate_* functions. The flag
is checked in skb_checksum_complete, so that validation is communicated
between checksum_init and checksum_complete sequence in TCP and UDP.

Signed-off-by: default avatarTom Herbert <therbert@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1054cc15

include/linux/skbuff.h

+14 −9
Original line number Diff line number Diff line
@@ -572,7 +572,8 @@ struct sk_buff { 
	 */

	__u8			encapsulation:1;

	__u8			encap_hdr_csum:1;

	/* 5/7 bit hole (depending on ndisc_nodetype presence) */

	__u8			csum_valid:1;

	/* 4/6 bit hole (depending on ndisc_nodetype presence) */

	kmemcheck_bitfield_end(flags2);



#if defined CONFIG_NET_DMA || defined CONFIG_NET_RX_BUSY_POLL
@@ -2735,7 +2736,7 @@ __sum16 __skb_checksum_complete(struct sk_buff *skb); 


static inline int skb_csum_unnecessary(const struct sk_buff *skb)

{

	return skb->ip_summed & CHECKSUM_UNNECESSARY;

	return ((skb->ip_summed & CHECKSUM_UNNECESSARY) || skb->csum_valid);

}



/**
@@ -2769,10 +2770,8 @@ 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;

	if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {

		skb->csum_valid = 1;

		return false;

	}
@@ -2799,15 +2798,20 @@ static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb, 
{

	if (skb->ip_summed == CHECKSUM_COMPLETE) {

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

			skb->ip_summed = CHECKSUM_UNNECESSARY;

			skb->csum_valid = 1;

			return 0;

		}

	}



	skb->csum = psum;



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

		return __skb_checksum_complete(skb);

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

		__sum16 csum;



		csum = __skb_checksum_complete(skb);

		skb->csum_valid = !csum;

		return csum;

	}



	return 0;

}
@@ -2831,6 +2835,7 @@ static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto) 
				zero_okay, check, compute_pseudo)	\

({									\

	__sum16 __ret = 0;						\

	skb->csum_valid = 0;						\

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

		__ret = __skb_checksum_validate_complete(skb,		\

				complete, compute_pseudo(skb, proto));	\