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[79.184.211.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b72896c8e3fsm45540666b.75.2025.11.05.12.19.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Nov 2025 12:19:58 -0800 (PST) From: Jakub Sitnicki Date: Wed, 05 Nov 2025 21:19:43 +0100 Subject: [PATCH bpf-next v4 06/16] bpf: Make bpf_skb_vlan_push helper metadata-safe Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20251105-skb-meta-rx-path-v4-6-5ceb08a9b37b@cloudflare.com> References: <20251105-skb-meta-rx-path-v4-0-5ceb08a9b37b@cloudflare.com> In-Reply-To: <20251105-skb-meta-rx-path-v4-0-5ceb08a9b37b@cloudflare.com> To: bpf@vger.kernel.org Cc: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Martin KaFai Lau , Daniel Borkmann , John Fastabend , Stanislav Fomichev , Alexei Starovoitov , Andrii Nakryiko , Eduard Zingerman , Song Liu , Yonghong Song , KP Singh , Hao Luo , Jiri Olsa , Arthur Fabre , Jesper Dangaard Brouer , netdev@vger.kernel.org, kernel-team@cloudflare.com X-Mailer: b4 0.15-dev-07fe9 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 --- 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