{"id":2226129,"url":"http://patchwork.ozlabs.org/api/patches/2226129/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260422094444.198178-3-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":"<20260422094444.198178-3-pablo@netfilter.org>","list_archive_url":null,"date":"2026-04-22T09:44:44","name":"[nf,v2,3/3] netfilter: nft_fwd_netdev: use recursion counter in neigh egress path","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"8320722c6cf2efcd14103d91f3a4dac6d534981c","submitter":{"id":1315,"url":"http://patchwork.ozlabs.org/api/people/1315/?format=json","name":"Pablo Neira Ayuso","email":"pablo@netfilter.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260422094444.198178-3-pablo@netfilter.org/mbox/","series":[{"id":500956,"url":"http://patchwork.ozlabs.org/api/series/500956/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/list/?series=500956","date":"2026-04-22T09:44:43","name":"[nf,v2,1/3] netfilter: replace skb_try_make_writable() by skb_ensure_writable()","version":2,"mbox":"http://patchwork.ozlabs.org/series/500956/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2226129/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2226129/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=F2KymRtx;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c0a:e001:db::12fc:5321; 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Wed, 22 Apr 2026 09:44:53 +0000 (UTC)","from localhost.localdomain (mail-agni [217.70.190.124])\n\tby mail.netfilter.org (Postfix) with ESMTPSA id CA0796017E\n\tfor ; Wed, 22 Apr 2026 11:44:51 +0200 (CEST)"],"ARC-Seal":"i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116;\n\tt=1776851094; cv=none;\n b=jBO6vVTrc/b89neF9bt/srnKa06ctndsTLVajK68u+VDuQBiybl0jAWZITAcywFVb9Zi1weUIzOu155qBHthYZKp3Rj/7YtUtNGQLYXF85zpO5Pue42oilIB0TTa5b/gUt1t1gdDZQeeyQgW/MW95Pd4XZtlMgZ18Nf8lZiJaS8=","ARC-Message-Signature":"i=1; a=rsa-sha256; d=subspace.kernel.org;\n\ts=arc-20240116; t=1776851094; c=relaxed/simple;\n\tbh=frOhg9qHKJ+e/ABNH67CCZQdXVCZvt6LgpZOjWR2xuA=;\n\th=From:To:Subject:Date:Message-ID:In-Reply-To:References:\n\t MIME-Version;\n b=WYLCARDcmY7MEfJChrt+rrBw1JttW8rX1Z4QxmHUPVUwRofELBJ2gT66dpw7yKJ3NA7NElHCcGv7EyAG0rsiKOg9iHiZ3bgirEdU0wpk2qhvfrgfeQ4e2VIdmhZE0bqgnpzQ0FKGP+qswUKTsVGDTIte8kTEHME/8P5EKfOL1u0=","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=F2KymRtx; 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=1776851091;\n\tbh=RAC6s5AkodAwF3xgiRD0CKvL05C6iqJd2onJgkd4jA0=;\n\th=From:To:Subject:Date:In-Reply-To:References:From;\n\tb=F2KymRtxpb64oBJpUDN9bZJ2K8KkdrJXhcSxrWXYzRJCyGIeBAea3LGF4Kj8sSU7z\n\t uSsshJjIKAEawS2td6mxpQL3EUDQccV8Y7dKYcsxefL5Z5XozSgwzYr9OGo26a9xyu\n\t YZTMP5gMxPFXCtFPPgXPhXcYUOWAavIfU34iyV2v0kKwZvI6kmqSXE64SUz1vjyncO\n\t 5MFFzoa3ZBH23xK4uh2h82ejIyaBBdlpgv1ReQE6PAoF966YlkBM/dcYQYYIPew+rH\n\t 78N4dcxKXmP7GDZbR89pnj9DCFBZba3EcvYkZB7Tx+Ixfa6XeeBqI/F9i+jJV206rd\n\t 3lUPL9RacFohg==","From":"Pablo Neira Ayuso ","To":"netfilter-devel@vger.kernel.org","Subject":"[PATCH nf,v2 3/3] netfilter: nft_fwd_netdev: use recursion counter in\n neigh egress path","Date":"Wed, 22 Apr 2026 11:44:44 +0200","Message-ID":"<20260422094444.198178-3-pablo@netfilter.org>","X-Mailer":"git-send-email 2.47.3","In-Reply-To":"<20260422094444.198178-1-pablo@netfilter.org>","References":"<20260422094444.198178-1-pablo@netfilter.org>","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":"From: Weiming Shi \n\nnft_fwd_neigh can be used in egress chains (NF_NETDEV_EGRESS). When the\nforwarding rule targets the same device or two devices forward to each\nother, neigh_xmit() triggers dev_queue_xmit() which re-enters\nnf_hook_egress(), causing infinite recursion and stack overflow.\n\nMove the nf_get_nf_dup_skb_recursion() accessor and NF_RECURSION_LIMIT\nto the shared header nf_dup_netdev.h as a static inline, so that\nnft_fwd_netdev can use the recursion counter directly without exported\nfunction call overhead. Guard neigh_xmit() with the same recursion\nlimit already used in nf_do_netdev_egress().\n\nFixes: f87b9464d152 (\"netfilter: nft_fwd_netdev: Support egress hook\")\nReported-by: Xiang Mei \nSigned-off-by: Weiming Shi \nSigned-off-by: Pablo Neira Ayuso \n---\nv2: no changes\n\n include/net/netfilter/nf_dup_netdev.h | 13 +++++++++++++\n net/netfilter/nf_dup_netdev.c | 16 ----------------\n net/netfilter/nft_fwd_netdev.c | 7 +++++++\n 3 files changed, 20 insertions(+), 16 deletions(-)","diff":"diff --git a/include/net/netfilter/nf_dup_netdev.h b/include/net/netfilter/nf_dup_netdev.h\nindex b175d271aec9..609bcf422a9b 100644\n--- a/include/net/netfilter/nf_dup_netdev.h\n+++ b/include/net/netfilter/nf_dup_netdev.h\n@@ -3,10 +3,23 @@\n #define _NF_DUP_NETDEV_H_\n \n #include \n+#include \n+#include \n \n void nf_dup_netdev_egress(const struct nft_pktinfo *pkt, int oif);\n void nf_fwd_netdev_egress(const struct nft_pktinfo *pkt, int oif);\n \n+#define NF_RECURSION_LIMIT\t2\n+\n+static inline u8 *nf_get_nf_dup_skb_recursion(void)\n+{\n+#ifndef CONFIG_PREEMPT_RT\n+\treturn this_cpu_ptr(&softnet_data.xmit.nf_dup_skb_recursion);\n+#else\n+\treturn ¤t->net_xmit.nf_dup_skb_recursion;\n+#endif\n+}\n+\n struct nft_offload_ctx;\n struct nft_flow_rule;\n \ndiff --git a/net/netfilter/nf_dup_netdev.c b/net/netfilter/nf_dup_netdev.c\nindex e348fb90b8dc..3b0a70e154cd 100644\n--- a/net/netfilter/nf_dup_netdev.c\n+++ b/net/netfilter/nf_dup_netdev.c\n@@ -13,22 +13,6 @@\n #include \n #include \n \n-#define NF_RECURSION_LIMIT\t2\n-\n-#ifndef CONFIG_PREEMPT_RT\n-static u8 *nf_get_nf_dup_skb_recursion(void)\n-{\n-\treturn this_cpu_ptr(&softnet_data.xmit.nf_dup_skb_recursion);\n-}\n-#else\n-\n-static u8 *nf_get_nf_dup_skb_recursion(void)\n-{\n-\treturn ¤t->net_xmit.nf_dup_skb_recursion;\n-}\n-\n-#endif\n-\n static void nf_do_netdev_egress(struct sk_buff *skb, struct net_device *dev,\n \t\t\t\tenum nf_dev_hooks hook)\n {\ndiff --git a/net/netfilter/nft_fwd_netdev.c b/net/netfilter/nft_fwd_netdev.c\nindex 95b2af3eede4..08deac69b254 100644\n--- a/net/netfilter/nft_fwd_netdev.c\n+++ b/net/netfilter/nft_fwd_netdev.c\n@@ -152,6 +152,11 @@ static void nft_fwd_neigh_eval(const struct nft_expr *expr,\n \t\tgoto out;\n \t}\n \n+\tif (*nf_get_nf_dup_skb_recursion() > NF_RECURSION_LIMIT) {\n+\t\tverdict = NF_DROP;\n+\t\tgoto out;\n+\t}\n+\n \tdev = dev_get_by_index_rcu(nft_net(pkt), oif);\n \tif (dev == NULL) {\n \t\tverdict = NF_DROP;\n@@ -160,7 +165,9 @@ static void nft_fwd_neigh_eval(const struct nft_expr *expr,\n \n \tskb->dev = dev;\n \tskb_clear_tstamp(skb);\n+\t(*nf_get_nf_dup_skb_recursion())++;\n \tneigh_xmit(neigh_table, dev, addr, skb);\n+\t(*nf_get_nf_dup_skb_recursion())--;\n out:\n \tregs->verdict.code = verdict;\n }\n","prefixes":["nf","v2","3/3"]}