{"id":2229260,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2229260/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260427224929.29868-1-pablo@netfilter.org/","project":{"id":26,"url":"http://patchwork.ozlabs.org/api/1.1/projects/26/?format=json","name":"Netfilter Development","link_name":"netfilter-devel","list_id":"netfilter-devel.vger.kernel.org","list_email":"netfilter-devel@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null},"msgid":"<20260427224929.29868-1-pablo@netfilter.org>","date":"2026-04-27T22:49:27","name":"[nf,v7,1/3] netfilter: replace skb_try_make_writable() by skb_ensure_writable()","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"c3281a270636241f67c06af26678734bf7e0171c","submitter":{"id":1315,"url":"http://patchwork.ozlabs.org/api/1.1/people/1315/?format=json","name":"Pablo Neira Ayuso","email":"pablo@netfilter.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260427224929.29868-1-pablo@netfilter.org/mbox/","series":[{"id":501740,"url":"http://patchwork.ozlabs.org/api/1.1/series/501740/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/list/?series=501740","date":"2026-04-27T22:49:29","name":"[nf,v7,1/3] netfilter: replace skb_try_make_writable() by skb_ensure_writable()","version":7,"mbox":"http://patchwork.ozlabs.org/series/501740/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2229260/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2229260/checks/","tags":{},"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","netfilter-devel@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=netfilter.org header.i=@netfilter.org\n header.a=rsa-sha256 header.s=2025 header.b=SVkezs/G;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.234.253.10; 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arc=none smtp.client-ip=217.70.190.124","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org;\n\ts=2025; t=1777330172;\n\tbh=0UfPkDr6It0h5TRChF527XWHGUjFoWq9buw8jCixh7M=;\n\th=From:To:Subject:Date:From;\n\tb=SVkezs/GzcmHlYo2WWqurZMswk72ZGYl4vOU2BZ7W1F/4dxwpPoEgUXEQyUJEHCvP\n\t Eiem3RnYynB+w3fHLf4BhEe1Sof0MPXMoi6Ij0q3Hb6/u5oGatG3wRI4+r/dGbidcf\n\t DyiG3m3dyweKZ1YrPTQoBhovctloxuRUx3yaidZ75BNgWTIosVEa531SbQwZvTzdAe\n\t JoEymB7Jjoojrvg8+at64rYScok81g3hD/nLKxYNL/muJotlakC2IekhJTozCv/eur\n\t NLxkLUXiPBe8wgjS3BKwvEJbHiQViIAhBqqi2qW2awMwaEaUmD3N0N4zK/KIGzWhE9\n\t BTtI3+56IxcGw==","From":"Pablo Neira Ayuso ","To":"netfilter-devel@vger.kernel.org","Subject":"[PATCH nf,v7 1/3] netfilter: replace skb_try_make_writable() by\n skb_ensure_writable()","Date":"Tue, 28 Apr 2026 00:49:27 +0200","Message-ID":"<20260427224929.29868-1-pablo@netfilter.org>","X-Mailer":"git-send-email 2.47.3","Precedence":"bulk","X-Mailing-List":"netfilter-devel@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit"},"content":"skb_try_make_writable() only works on clones and uncloned packets might\nhave their network header in paged fragments.\n\nnft_fwd needs to work for the ingress and egress hooks, but the egress\nhook where skb->data points to the mac header, use skb_network_offset()\nto include the mac header. The flowtable is fine since it already uses\nthe transport offset.\n\nFixes: d32de98ea70f (\"netfilter: nft_fwd_netdev: allow to forward packets via neighbour layer\")\nFixes: 7d2086871762 (\"netfilter: nf_flow_table: move ipv4 offload hook code to nf_flow_table\")\nSigned-off-by: Pablo Neira Ayuso \n---\nv7: no changes, previous v6 posted on the ML has duplicated 1/3 and 2/3.\n\n net/netfilter/nf_flow_table_ip.c | 4 ++--\n net/netfilter/nft_fwd_netdev.c | 5 +++--\n 2 files changed, 5 insertions(+), 4 deletions(-)","diff":"diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c\nindex fd56d663cb5b..dbd7644fdbeb 100644\n--- a/net/netfilter/nf_flow_table_ip.c\n+++ b/net/netfilter/nf_flow_table_ip.c\n@@ -524,7 +524,7 @@ static int nf_flow_offload_forward(struct nf_flowtable_ctx *ctx,\n \t\treturn 0;\n \t}\n \n-\tif (skb_try_make_writable(skb, thoff + ctx->hdrsize))\n+\tif (skb_ensure_writable(skb, thoff + ctx->hdrsize))\n \t\treturn -1;\n \n \tflow_offload_refresh(flow_table, flow, false);\n@@ -1037,7 +1037,7 @@ static int nf_flow_offload_ipv6_forward(struct nf_flowtable_ctx *ctx,\n \t\treturn 0;\n \t}\n \n-\tif (skb_try_make_writable(skb, thoff + ctx->hdrsize))\n+\tif (skb_ensure_writable(skb, thoff + ctx->hdrsize))\n \t\treturn -1;\n \n \tflow_offload_refresh(flow_table, flow, false);\ndiff --git a/net/netfilter/nft_fwd_netdev.c b/net/netfilter/nft_fwd_netdev.c\nindex 4bce36c3a6a0..2cc809303ce8 100644\n--- a/net/netfilter/nft_fwd_netdev.c\n+++ b/net/netfilter/nft_fwd_netdev.c\n@@ -100,6 +100,7 @@ static void nft_fwd_neigh_eval(const struct nft_expr *expr,\n \tint oif = regs->data[priv->sreg_dev];\n \tunsigned int verdict = NF_STOLEN;\n \tstruct sk_buff *skb = pkt->skb;\n+\tint nhoff = skb_network_offset(skb);\n \tstruct net_device *dev;\n \tint neigh_table;\n \n@@ -111,7 +112,7 @@ static void nft_fwd_neigh_eval(const struct nft_expr *expr,\n \t\t\tverdict = NFT_BREAK;\n \t\t\tgoto out;\n \t\t}\n-\t\tif (skb_try_make_writable(skb, sizeof(*iph))) {\n+\t\tif (skb_ensure_writable(skb, nhoff + sizeof(*iph))) {\n \t\t\tverdict = NF_DROP;\n \t\t\tgoto out;\n \t\t}\n@@ -132,7 +133,7 @@ static void nft_fwd_neigh_eval(const struct nft_expr *expr,\n \t\t\tverdict = NFT_BREAK;\n \t\t\tgoto out;\n \t\t}\n-\t\tif (skb_try_make_writable(skb, sizeof(*ip6h))) {\n+\t\tif (skb_ensure_writable(skb, nhoff + sizeof(*ip6h))) {\n \t\t\tverdict = NF_DROP;\n \t\t\tgoto out;\n \t\t}\n","prefixes":["nf","v7","1/3"]}