net: Rename and export copy_skb_header

jira VULN-1439
cve-prereq CVE-2022-33741
commit-author Ilya Lesokhin <[email protected]>
commit 08303c1

copy_skb_header is renamed to skb_copy_header and
exported. Exposing this function give more flexibility
in copying SKBs.
skb_copy and skb_copy_expand do not give enough control
over which parts are copied.

	Signed-off-by: Ilya Lesokhin <[email protected]>
	Signed-off-by: Boris Pismenny <[email protected]>
	Signed-off-by: David S. Miller <[email protected]>
(cherry picked from commit 08303c1)
	Signed-off-by: Brett Mastbergen <[email protected]>

Author: bmastbergen

include/linux/skbuff.h

@@ -1030,6 +1030,7 @@ static inline struct sk_buff *alloc_skb_head(gfp_t priority)
 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t priority);
+void skb_copy_header(struct sk_buff *new, const struct sk_buff *old);
 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t priority);
 struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom, gfp_t gfp_mask);
 

net/core/skbuff.c

@@ -1115,14 +1115,15 @@ static void skb_headers_offset_update(struct sk_buff *skb, int off)
 	skb->inner_mac_header += off;
 }
 
-static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
+void skb_copy_header(struct sk_buff *new, const struct sk_buff *old)
 {
 	__copy_skb_header(new, old);
 
 	skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
 	skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
 	skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
 }
+EXPORT_SYMBOL(skb_copy_header);
 
 static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
 {
@@ -1166,7 +1167,7 @@ struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
 	if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
 		BUG();
 
-	copy_skb_header(n, skb);
+	skb_copy_header(n, skb);
 	return n;
 }
 EXPORT_SYMBOL(skb_copy);
@@ -1225,7 +1226,7 @@ struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom, gfp_t gfp_mask)
 		skb_clone_fraglist(n);
 	}
 
-	copy_skb_header(n, skb);
+	skb_copy_header(n, skb);
 out:
 	return n;
 }
@@ -1396,7 +1397,7 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
 			  skb->len + head_copy_len))
 		BUG();
 
-	copy_skb_header(n, skb);
+	skb_copy_header(n, skb);
 
 	skb_headers_offset_update(n, newheadroom - oldheadroom);