summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorLuiz Augusto von Dentz <luiz.von.dentz@intel.com>2021-12-01 21:54:52 +0300
committerMarcel Holtmann <marcel@holtmann.org>2021-12-07 19:05:38 +0300
commit13244cccc2b61ec715f0ac583d3037497004d4a5 (patch)
treea6f62154833573b637d1ce75ac7ca99b88311da2
parent561ae1d46a8ddcbc13162d5771f5ed6c8249e730 (diff)
downloadlinux-13244cccc2b61ec715f0ac583d3037497004d4a5.tar.xz
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 <kuba@kernel.org> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
-rw-r--r--include/linux/skbuff.h2
-rw-r--r--net/core/skbuff.c24
2 files changed, 26 insertions, 0 deletions
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..dd3ef966efdb 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2024,6 +2024,30 @@ 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
* @len: new length