Commit 13244ccc authored by Luiz Augusto von Dentz's avatar Luiz Augusto von Dentz Committed by Marcel Holtmann
Browse files

skbuff: introduce skb_pull_data 



Like skb_pull but returns the original data pointer before pulling the
data after performing a check against sbk->len.

This allows to change code that does "struct foo *p = (void *)skb->data;"
which is hard to audit and error prone, to:

        p = skb_pull_data(skb, sizeof(*p));
        if (!p)
                return;

Which is both safer and cleaner.

Acked-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarLuiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarMarcel Holtmann <marcel@holtmann.org>
parent 561ae1d4

include/linux/skbuff.h

+2 −0
Original line number Diff line number Diff line
@@ -2373,6 +2373,8 @@ static inline void *skb_pull_inline(struct sk_buff *skb, unsigned int len) 
	return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);

}



void *skb_pull_data(struct sk_buff *skb, size_t len);



void *__pskb_pull_tail(struct sk_buff *skb, int delta);



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

net/core/skbuff.c

+24 −0
Original line number Diff line number Diff line
@@ -2023,6 +2023,30 @@ void *skb_pull(struct sk_buff *skb, unsigned int len) 
}

EXPORT_SYMBOL(skb_pull);



/**

 *	skb_pull_data - remove data from the start of a buffer returning its

 *	original position.

 *	@skb: buffer to use

 *	@len: amount of data to remove

 *

 *	This function removes data from the start of a buffer, returning

 *	the memory to the headroom. A pointer to the original data in the buffer

 *	is returned after checking if there is enough data to pull. Once the

 *	data has been pulled future pushes will overwrite the old data.

 */

void *skb_pull_data(struct sk_buff *skb, size_t len)

{

	void *data = skb->data;



	if (skb->len < len)

		return NULL;



	skb_pull(skb, len);



	return data;

}

EXPORT_SYMBOL(skb_pull_data);



/**

 *	skb_trim - remove end from a buffer

 *	@skb: buffer to alter