Commit 55ffc98b authored by Jakub Sitnicki's avatar Jakub Sitnicki Committed by Martin KaFai Lau
Browse files

bpf: Make bpf_skb_vlan_push helper metadata-safe 



Use the metadata-aware helper to move packet bytes after skb_push(),
ensuring metadata remains valid after calling the BPF helper.

Also, take care to reserve sufficient headroom for metadata to fit.

Signed-off-by: default avatarJakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20251105-skb-meta-rx-path-v4-6-5ceb08a9b37b@cloudflare.com
parent efd35c26

include/linux/if_vlan.h

+3 −2
Original line number Diff line number Diff line
@@ -355,16 +355,17 @@ static inline int __vlan_insert_inner_tag(struct sk_buff *skb, 
					  __be16 vlan_proto, u16 vlan_tci,

					  unsigned int mac_len)

{

	const u8 meta_len = mac_len > ETH_TLEN ? skb_metadata_len(skb) : 0;

	struct vlan_ethhdr *veth;



	if (skb_cow_head(skb, VLAN_HLEN) < 0)

	if (skb_cow_head(skb, meta_len + VLAN_HLEN) < 0)

		return -ENOMEM;



	skb_push(skb, VLAN_HLEN);



	/* Move the mac header sans proto to the beginning of the new header. */

	if (likely(mac_len > ETH_TLEN))

		memmove(skb->data, skb->data + VLAN_HLEN, mac_len - ETH_TLEN);

		skb_postpush_data_move(skb, VLAN_HLEN, mac_len - ETH_TLEN);

	if (skb_mac_header_was_set(skb))

		skb->mac_header -= VLAN_HLEN;