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[79.184.211.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b728937cc82sm45038766b.21.2025.11.05.12.19.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Nov 2025 12:19:59 -0800 (PST) From: Jakub Sitnicki Date: Wed, 05 Nov 2025 21:19:44 +0100 Subject: [PATCH bpf-next v4 07/16] bpf: Make bpf_skb_adjust_room 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-v4-7-5ceb08a9b37b@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 bpf_skb_adjust_room() may push or pull bytes from skb->data. In both cases, skb metadata must be moved accordingly to stay accessible. Replace existing memmove() calls, which only move payload, with a helper that also handles metadata. Reserve enough space for metadata to fit after skb_push. Signed-off-by: Jakub Sitnicki --- net/core/filter.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index 96714eab9c91..370ddc61bc72 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3260,11 +3260,11 @@ static void bpf_skb_change_protocol(struct sk_buff *skb, u16 proto) static int bpf_skb_generic_push(struct sk_buff *skb, u32 off, u32 len) { - /* Caller already did skb_cow() with len as headroom, + /* Caller already did skb_cow() with meta_len+len as headroom, * so no need to do it here. */ skb_push(skb, len); - memmove(skb->data, skb->data + len, off); + skb_postpush_data_move(skb, len, off); memset(skb->data + off, 0, len); /* No skb_postpush_rcsum(skb, skb->data + off, len) @@ -3288,7 +3288,7 @@ static int bpf_skb_generic_pop(struct sk_buff *skb, u32 off, u32 len) old_data = skb->data; __skb_pull(skb, len); skb_postpull_rcsum(skb, old_data + off, len); - memmove(skb->data, old_data, off); + skb_postpull_data_move(skb, len, off); return 0; } @@ -3496,6 +3496,7 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff, u8 inner_mac_len = flags >> BPF_ADJ_ROOM_ENCAP_L2_SHIFT; bool encap = flags & BPF_F_ADJ_ROOM_ENCAP_L3_MASK; u16 mac_len = 0, inner_net = 0, inner_trans = 0; + const u8 meta_len = skb_metadata_len(skb); unsigned int gso_type = SKB_GSO_DODGY; int ret; @@ -3506,7 +3507,7 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff, return -ENOTSUPP; } - ret = skb_cow_head(skb, len_diff); + ret = skb_cow_head(skb, meta_len + len_diff); if (unlikely(ret < 0)) return ret; -- 2.43.0