{"id":2226700,"url":"http://patchwork.ozlabs.org/api/patches/2226700/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260422183429.240452-1-pablo@netfilter.org/","project":{"id":26,"url":"http://patchwork.ozlabs.org/api/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,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260422183429.240452-1-pablo@netfilter.org>","list_archive_url":null,"date":"2026-04-22T18:34:27","name":"[nf,v3,1/3] netfilter: replace skb_try_make_writable() by skb_ensure_writable()","commit_ref":null,"pull_url":null,"state":"superseded","archived":true,"hash":"c3281a270636241f67c06af26678734bf7e0171c","submitter":{"id":1315,"url":"http://patchwork.ozlabs.org/api/people/1315/?format=json","name":"Pablo Neira Ayuso","email":"pablo@netfilter.org"},"delegate":{"id":11902,"url":"http://patchwork.ozlabs.org/api/users/11902/?format=json","username":"strlen","first_name":"Florian","last_name":"Westphal","email":"fw@strlen.de"},"mbox":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260422183429.240452-1-pablo@netfilter.org/mbox/","series":[{"id":501077,"url":"http://patchwork.ozlabs.org/api/series/501077/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/list/?series=501077","date":"2026-04-22T18:34:28","name":"[nf,v3,1/3] netfilter: replace skb_try_make_writable() by skb_ensure_writable()","version":3,"mbox":"http://patchwork.ozlabs.org/series/501077/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2226700/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2226700/checks/","tags":{},"related":[],"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=Lohe2ZoE;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=104.64.211.4; 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t=1776882884; c=relaxed/simple;\n\tbh=hGzP2lYMCo4QvpN2I8esGTeVwX6Ek1wZGvPJAQ7Ekq4=;\n\th=From:To:Subject:Date:Message-ID:MIME-Version;\n b=GKYj3mTJab4H/fcaxUhzusf1O8hXhzaAxm4j8kMi66LT653qUxyg2rBBpe8a5Sd6BlBadcqZjM+UGbLMwSAosvp/CLHEakn76AClG+Y12QYBf/2eEqqkLlwwy+a49CAv6GWxyDJw3NmNGG0FCg+xlemNF6LC5kDPPjmsPyOxQZw=","ARC-Authentication-Results":"i=1; smtp.subspace.kernel.org;\n dmarc=none (p=none dis=none) header.from=netfilter.org;\n spf=pass smtp.mailfrom=netfilter.org;\n dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org\n header.b=Lohe2ZoE; 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=1776882872;\n\tbh=sV7tBI/ddYEK6pE0N5GS5pxvGpHY18e1WFFc43aQcmw=;\n\th=From:To:Subject:Date:From;\n\tb=Lohe2ZoEEi2K3o80t9749+hxqAIJlVtZaSGcrS3ARMUMJNRs+ECEY63vD6v3x+sC6\n\t h/+aFxMMfCAumIAwdmbm/j6eodjQni7GQOLlMw7UBOqpStLq/HOegv5iiamcA+bjF+\n\t dEO4PR7juo5LUeN5oyUVV5DIDjUUzZ9oSpepsRsggugnols1LVwNz+CNUA9fRdAhhR\n\t 7wyPFulevd6bQ7C4ABcj9Fa5UQFMZP4B7S7eP5meIRfd1FjwZZzoGpTuYLKaztHZHD\n\t bV9QNfmJcXkFyIQyrBGUGzS/7Rb41oyHdHXFiPtEbzR9H2lBPqAxaKK/Mrnmdx9K7B\n\t ZErwzL7ldpEOA==","From":"Pablo Neira Ayuso ","To":"netfilter-devel@vger.kernel.org","Subject":"[PATCH nf,v3 1/3] netfilter: replace skb_try_make_writable() by\n skb_ensure_writable()","Date":"Wed, 22 Apr 2026 20:34:27 +0200","Message-ID":"<20260422183429.240452-1-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---\nv3: apparently I posted a patch version which does not compile.\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","v3","1/3"]}