netdev - [PATCH net-next 3/8] netfilter: nft_payload: rebuild vlan header when needed

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Message-Id: <20230626064749.75525-4-pablo@netfilter.org>
Date: Mon, 26 Jun 2023 08:47:44 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net,
	netdev@...r.kernel.org,
	kuba@...nel.org,
	pabeni@...hat.com,
	edumazet@...gle.com
Subject: [PATCH net-next 3/8] netfilter: nft_payload: rebuild vlan header when needed

Skip rebuilding the vlan header when accessing destination and source
mac address.

Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nft_payload.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nft_payload.c b/net/netfilter/nft_payload.c
index 3a3c7746e88f..8cb800989947 100644
--- a/net/netfilter/nft_payload.c
+++ b/net/netfilter/nft_payload.c
@@ -171,7 +171,8 @@ void nft_payload_eval(const struct nft_expr *expr,
 		if (!skb_mac_header_was_set(skb))
 			goto err;
 
-		if (skb_vlan_tag_present(skb)) {
+		if (skb_vlan_tag_present(skb) &&
+		    priv->offset >= offsetof(struct ethhdr, h_proto)) {
 			if (!nft_payload_copy_vlan(dest, skb,
 						   priv->offset, priv->len))
 				goto err;
-- 
2.30.2