netdev - [PATCH RFC bpf-next 1/9] net: Preserve metadata on pskb_expand

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Message-Id: <20250929-skb-meta-rx-path-v1-1-de700a7ab1cb@cloudflare.com>
Date: Mon, 29 Sep 2025 16:09:06 +0200
From: Jakub Sitnicki <jakub@...udflare.com>
To: bpf@...r.kernel.org
Cc: netdev@...r.kernel.org, kernel-team@...udflare.com
Subject: [PATCH RFC bpf-next 1/9] 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 a headroom reallocation.

Let the skb metadata be in the newly created copy of head.

Signed-off-by: Jakub Sitnicki <jakub@...udflare.com>
---
 net/core/skbuff.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index ee0274417948..dd58cc9c997f 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2288,8 +2288,6 @@ 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).

-- 
2.43.0