diff options
| author | Jakub Sitnicki <jakub@cloudflare.com> | 2025-11-05 21:19:39 +0100 |
|---|---|---|
| committer | Martin KaFai Lau <martin.lau@kernel.org> | 2025-11-10 10:52:31 -0800 |
| commit | 290fc0be09e2f6e08754782616bb7e67f8191fa1 (patch) | |
| tree | 4bfa1d8c8ffbc429d9b2f461b079f70c2786e6e5 /net/core | |
| parent | 8989d328dfe7c7a3b9f4b9f0ef60006d277f81cc (diff) | |
net: Preserve metadata on pskb_expand_head
pskb_expand_head() copies headroom, including skb metadata, into the newly
allocated head, but then clears the metadata. As a result, metadata is lost
when BPF helpers trigger an skb head reallocation.
Let the skb metadata remain in the newly created copy of head.
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20251105-skb-meta-rx-path-v4-2-5ceb08a9b37b@cloudflare.com
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/skbuff.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 7ac5f8aa1235..d95658b738d1 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -2234,6 +2234,10 @@ EXPORT_SYMBOL(__pskb_copy_fclone); * * All the pointers pointing into skb header may change and must be * reloaded after call to this function. + * + * Note: If you skb_push() the start of the buffer after reallocating the + * header, call skb_postpush_data_move() first to move the metadata out of + * the way before writing to &sk_buff->data. */ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, @@ -2305,8 +2309,6 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, skb->nohdr = 0; atomic_set(&skb_shinfo(skb)->dataref, 1); - skb_metadata_clear(skb); - /* It is not generally safe to change skb->truesize. * For the moment, we really care of rx path, or * when skb is orphaned (not attached to a socket). |