[PATCH 01/15] skbuff: introduce skb_pull_data
STALE1665d
From: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date: 2021-12-01 00:03:05
Also in:
linux-bluetooth
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Revision v1 of 2 in this series.
Revisions (2)
- v1 current
- v2 [diff vs current]
From: Luiz Augusto von Dentz <redacted>
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.
Signed-off-by: Luiz Augusto von Dentz <redacted>
Signed-off-by: Dan Carpenter <redacted>
---
include/linux/skbuff.h | 2 ++
net/core/skbuff.c | 23 +++++++++++++++++++++++
2 files changed, 25 insertions(+)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index eba256af64a5..877dda38684a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h@@ -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)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index a33247fdb8f5..0b19833ffbce 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c@@ -2023,6 +2023,29 @@ 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; +} + /** * skb_trim - remove end from a buffer * @skb: buffer to alter
--
2.33.1