From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f46.google.com (mail-pj1-f46.google.com [209.85.216.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A6BE437B402 for ; Thu, 9 Apr 2026 10:49:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775731794; cv=none; b=QAWP9JTkiYkvO7bQt0cw+fGCFI8jTf5Fag1ag4Y6FGLAxAWIOArUl+doANa8KY/5mKViAfiMYXWUixC0qYsJzKD+f9rRY8oCpt6AG5M+oREJYKUdJrZVg1+uleUhJvZ3lk84ZuYqjVXQXiKaQ6XaU3rX7WQ5I3XpuxGA+zTtqrA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775731794; c=relaxed/simple; bh=JNT33Wmq43E/C5jtUNTbbsnfLcnJM8zf0ttEv/gKCIs=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=cm+Sif9YNwJJWR8ODMZwUSu1Bxl37H023vwXvFmu57gYXknjUQzJXfFcbk9iXMdlj9+8vevYlfOxn+UjxdE67WMSCsQMGkO1toEX7O5gzELR/ptwsxFppq0EuZCmXnlRZ/sNtNo4P+1OLDNK1tK4elL9wZLjfYwN8XZW3wJ+n4Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=WwfcPWkk; arc=none smtp.client-ip=209.85.216.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="WwfcPWkk" Received: by mail-pj1-f46.google.com with SMTP id 98e67ed59e1d1-358e3cc5e7eso470029a91.0 for ; Thu, 09 Apr 2026 03:49:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1775731791; x=1776336591; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=Ukbyd6N1MhmvxaPd3moBUEUJpBd5mNCDxCGpsq2J5LA=; b=WwfcPWkkwJgxDug0ekTYyXrV/xouXrB9HBUMAfrkdkjELiDzkLUX2IODG1upfUYKYS jQg2msyCQT2bCu989fFE1Fo3LBhWrj24SXXnKNVBEmtaYBzici0xmgW4x7yUQCsmr4Ng dUmgiCYZ1N0VcOTT3NuU09Ox/EjbbNq2zYCgLagY68DHcXt8h5101pDtWyWLJ2Y2eZTH ocM91IvDxQV1T59o+yWxCbdcPLiSTgLfGp7zmk9TMjf8XsNpBs9AHYYkgyCui7svfK+N ZGGrjjL8LlptLrTzzzI2MmViOu5jDKgOZ1Jn38iEOLJY6o8poGqBvKW+pdqV+EAlDsw6 1K5w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775731791; x=1776336591; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=Ukbyd6N1MhmvxaPd3moBUEUJpBd5mNCDxCGpsq2J5LA=; b=j2pALB+NEAG6GueCq9vRrH1WpwX6T1xv49l3BoxNtuyokYeffoQzOm3+T22Z/e4wcR Z9Pvv+BJj9IAsCpUcJDqDLoEHYjOF6R9WHAb6jlwI9nCEBPYJMvykokC9890ePMRpJih YKmZ6pGFOxtX+6A+K86ZMySsojijGaGNq6rvfHZ5VInEXWRd8VT4Qd02uIEfokn++NsQ gzAhqtIUGYrj71lfR+9ymlZRoQM7SLtBFMDIzDiwQN5v9+Txn4o8YvdvUBcg3vNsDdXB sn0VRxmt8pFZ7yX8jdJlSU+xXkz320MQ0mb3c/VcCcCW91B7asdH5Aj6EMlbC0WtEdsg c3zA== X-Forwarded-Encrypted: i=1; AJvYcCXQ1Y5x3WTvtg84jhA60YsqycbYlUbstssvHCcS3E3uJ95Xs0UrnfPAQMoyIMrlucoqxMg23Ahz/AdbEOj9rdM=@vger.kernel.org X-Gm-Message-State: AOJu0YwxkDYBVCE3meIqXDC1kaLyRrAn5/RaqHV1tIVRTb6/+zzOdkpt kc7xnY/QyaSsRjalfVX7FEpDfwvUQoYU4ydwIspUd0WhdFnmpn+Mo1gj X-Gm-Gg: AeBDievlXFlPaSs5qMmSPR2ijat+7d0VOH5Ibu21AAhccXqadSHEWoYtqCFrU3dXF74 obWir18pso2Y5+CsZuy2+Zh026PaNZoeR4dobE7QqdpHB3Bn+NfPjnlpdhXOc8TFWzdYyZg40l0 EnT69HH707HSOGhnLDpZTB+n5UJkuMEivtoiBfN4SFwlSy/TmfHwLYTfqFfuEXwYxAS0d66najA OtQh7c6tPtRl9veionwJqS+/FWZihC4Avn/v5R7BWj31pfouFo5rLYwKKyIHf7muy3CnQ66aU9I MXA1cWsXUoAXog7jsJQZlJlFtVCxuWwYa9wQTdh/13jNEwA5Xg7LBHpfaI1vcmnj1n2qadwIDdH IPP+Gx0IBg8KhhBkX2W8wOCeuuEDx5VV7loB1N9Ovjlbb8BwdVAHy9QjfF3nEj7CRoSjhzE3m7w 3WnQ5LyZhEudkLYbARyKeE3OHSsDgIQvnsf24l4j5uhJ9rPNTElIjf17jMLFulYYtg+kNv7/DvH XunqebMEwLc X-Received: by 2002:a17:90b:5585:b0:355:35b0:8b78 with SMTP id 98e67ed59e1d1-35de69a6545mr23786223a91.27.1775731790627; Thu, 09 Apr 2026 03:49:50 -0700 (PDT) Received: from SLSGDTSWING002.tail0ac356.ts.net ([129.126.109.177]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-35e3503b278sm3724426a91.16.2026.04.09.03.49.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Apr 2026 03:49:50 -0700 (PDT) From: Weiming Shi To: Pablo Neira Ayuso , Florian Westphal , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Phil Sutter , Simon Horman , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, Xiang Mei , Weiming Shi Subject: [PATCH v2] netfilter: nft_fwd_netdev: use recursion counter in neigh egress path Date: Thu, 9 Apr 2026 18:49:12 +0800 Message-ID: <20260409104911.722698-2-bestswngs@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: netfilter-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit nft_fwd_neigh can be used in egress chains (NF_NETDEV_EGRESS). When the forwarding rule targets the same device or two devices forward to each other, neigh_xmit() triggers dev_queue_xmit() which re-enters nf_hook_egress(), causing infinite recursion and stack overflow. Move the nf_get_nf_dup_skb_recursion() accessor and NF_RECURSION_LIMIT to the shared header nf_dup_netdev.h as a static inline, so that nft_fwd_netdev can use the recursion counter directly without exported function call overhead. Guard neigh_xmit() with the same recursion limit already used in nf_do_netdev_egress(). Fixes: f87b9464d152 ("netfilter: nft_fwd_netdev: Support egress hook") Reported-by: Xiang Mei Signed-off-by: Weiming Shi --- include/net/netfilter/nf_dup_netdev.h | 13 +++++++++++++ net/netfilter/nf_dup_netdev.c | 16 ---------------- net/netfilter/nft_fwd_netdev.c | 7 +++++++ 3 files changed, 20 insertions(+), 16 deletions(-) diff --git a/include/net/netfilter/nf_dup_netdev.h b/include/net/netfilter/nf_dup_netdev.h index b175d271aec9..609bcf422a9b 100644 --- a/include/net/netfilter/nf_dup_netdev.h +++ b/include/net/netfilter/nf_dup_netdev.h @@ -3,10 +3,23 @@ #define _NF_DUP_NETDEV_H_ #include +#include +#include void nf_dup_netdev_egress(const struct nft_pktinfo *pkt, int oif); void nf_fwd_netdev_egress(const struct nft_pktinfo *pkt, int oif); +#define NF_RECURSION_LIMIT 2 + +static inline u8 *nf_get_nf_dup_skb_recursion(void) +{ +#ifndef CONFIG_PREEMPT_RT + return this_cpu_ptr(&softnet_data.xmit.nf_dup_skb_recursion); +#else + return ¤t->net_xmit.nf_dup_skb_recursion; +#endif +} + struct nft_offload_ctx; struct nft_flow_rule; diff --git a/net/netfilter/nf_dup_netdev.c b/net/netfilter/nf_dup_netdev.c index fab8b9011098..a958a1b0c5be 100644 --- a/net/netfilter/nf_dup_netdev.c +++ b/net/netfilter/nf_dup_netdev.c @@ -13,22 +13,6 @@ #include #include -#define NF_RECURSION_LIMIT 2 - -#ifndef CONFIG_PREEMPT_RT -static u8 *nf_get_nf_dup_skb_recursion(void) -{ - return this_cpu_ptr(&softnet_data.xmit.nf_dup_skb_recursion); -} -#else - -static u8 *nf_get_nf_dup_skb_recursion(void) -{ - return ¤t->net_xmit.nf_dup_skb_recursion; -} - -#endif - static void nf_do_netdev_egress(struct sk_buff *skb, struct net_device *dev, enum nf_dev_hooks hook) { diff --git a/net/netfilter/nft_fwd_netdev.c b/net/netfilter/nft_fwd_netdev.c index 152a9fb4d23a..492bb599a499 100644 --- a/net/netfilter/nft_fwd_netdev.c +++ b/net/netfilter/nft_fwd_netdev.c @@ -141,13 +141,20 @@ static void nft_fwd_neigh_eval(const struct nft_expr *expr, goto out; } + if (*nf_get_nf_dup_skb_recursion() > NF_RECURSION_LIMIT) { + verdict = NF_DROP; + goto out; + } + dev = dev_get_by_index_rcu(nft_net(pkt), oif); if (dev == NULL) return; skb->dev = dev; skb_clear_tstamp(skb); + (*nf_get_nf_dup_skb_recursion())++; neigh_xmit(neigh_table, dev, addr, skb); + (*nf_get_nf_dup_skb_recursion())--; out: regs->verdict.code = verdict; } -- 2.43.0