netdev - [PATCH RFC bpf-next 09/15] xdp: Call skb_metadata_set when skb->data points at metadata end

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20251124-skb-meta-safeproof-netdevs-rx-only-v1-9-8978f5054417@cloudflare.com>
Date: Mon, 24 Nov 2025 17:28:45 +0100
From: Jakub Sitnicki <jakub@...udflare.com>
To: bpf@...r.kernel.org
Cc: netdev@...r.kernel.org, kernel-team@...udflare.com, 
 Martin KaFai Lau <martin.lau@...ux.dev>
Subject: [PATCH RFC bpf-next 09/15] xdp: Call skb_metadata_set when
 skb->data points at metadata end

Prepare to track skb metadata location independently of MAC header offset.

Following changes will make skb_metadata_set() record where metadata ends
relative to skb->head. Hence the helper must be called when skb->data
points just past the metadata area.

Tweak XDP generic mode accordingly.

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 69515edd17bc..70cf90d5c73c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5461,8 +5461,11 @@ 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