[PATCH bpf-next v2 05/15] bpf: Make bpf_skb_vlan_push helper metadata-safe
From: Jakub Sitnicki <jakub@cloudflare.com>
Date: 2025-10-19 12:45:50
Also in:
bpf
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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> --- include/linux/if_vlan.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index 4ecc2509b0d4..f7f34eb15e06 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h@@ -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;
--
2.43.0