netdev - [PATCH net-next 10/10] xdp: Call skb_metadata_set when skb->data points past metadata

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Message-Id: <20260110-skb-meta-fixup-skb_metadata_set-calls-v1-10-1047878ed1b0@cloudflare.com>
Date: Sat, 10 Jan 2026 22:05:24 +0100
From: Jakub Sitnicki <jakub@...udflare.com>
To: netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
 Michael Chan <michael.chan@...adcom.com>, 
 Pavan Chebbi <pavan.chebbi@...adcom.com>, 
 Andrew Lunn <andrew+netdev@...n.ch>, 
 Tony Nguyen <anthony.l.nguyen@...el.com>, 
 Przemek Kitszel <przemyslaw.kitszel@...el.com>, 
 Saeed Mahameed <saeedm@...dia.com>, Leon Romanovsky <leon@...nel.org>, 
 Tariq Toukan <tariqt@...dia.com>, Mark Bloch <mbloch@...dia.com>, 
 Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
 Jesper Dangaard Brouer <hawk@...nel.org>, 
 John Fastabend <john.fastabend@...il.com>, 
 Stanislav Fomichev <sdf@...ichev.me>, intel-wired-lan@...ts.osuosl.org, 
 bpf@...r.kernel.org, kernel-team@...udflare.com
Subject: [PATCH net-next 10/10] xdp: Call skb_metadata_set when skb->data
 points past metadata

Prepare to copy the XDP metadata into an skb extension in skb_metadata_set.

XDP generic mode runs after MAC header has been already pulled. Adjust
skb->data before calling skb_metadata_set to adhere to new contract.

Signed-off-by: Jakub Sitnicki <jakub@...udflare.com>
---
 net/core/dev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index c711da335510..f8e5672e835f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5468,8 +5468,11 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
 		break;
 	case XDP_PASS:
 		metalen = xdp->data - xdp->data_meta;
-		if (metalen)
+		if (metalen) {
+			__skb_push(skb, mac_len);
 			skb_metadata_set(skb, metalen);
+			__skb_pull(skb, mac_len);
+		}
 		break;
 	}

-- 
2.43.0