From 13244cccc2b61ec715f0ac583d3037497004d4a5 Mon Sep 17 00:00:00 2001 From: Luiz Augusto von Dentz Date: Wed, 1 Dec 2021 10:54:52 -0800 Subject: 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: Jakub Kicinski Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Dan Carpenter Signed-off-by: Marcel Holtmann --- net/core/skbuff.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'net') diff --git a/net/core/skbuff.c b/net/core/skbuff.c index a33247fdb8f5..dd3ef966efdb 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -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 -- cgit v1.2.3