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bpf: Make bpf_skb_vlan_push helper metadata-safe

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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: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20251105-skb-meta-rx-path-v4-6-5ceb08a9b37b@cloudflare.com
This commit is contained in:
Jakub Sitnicki
2025-11-05 21:19:43 +01:00
committed by Martin KaFai Lau
parent efd35c2623
commit 55ffc98b44
1 changed files with 3 additions and 2 deletions
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5
include/linux/if_vlan.h
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@@ -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;