From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BF6D847127A; Tue, 21 Jul 2026 18:51:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784659898; cv=none; b=B0leis3VNUx3rSNAIHBUjnB29Dq48AoEfDkUj2kW/hYuVUmpCjMQmYKG8qsh5PrRhMVuQdKcPfUTo6/nJ+yn6tMnYQyh1CsWu7XYo5Fy0KT1TkRZLLUzgJPdYNLUcxPqMkVQHvJhs4d6cyu6qVcaypSOs4ogFREJfsD93YMQHoU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784659898; c=relaxed/simple; bh=gZgeXd26PO7+XjFUekphY72626wU5GA5ydTmNGVk+Nc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cwxPCG6H3+bPO8+QPvkeRlV7ZRe/4IFv72orDvzKqRogg8P05D/NcT38wnSl7iKBy7SN4TVAWmqGBei+bEgHlVH72fOCQnpsfgyjSxdFqKcEkQF+GEG7EJnD36r6V20a5bPdmmgXDaYTPFi7n/ecQhseyex+XtgTRvWh0uzbGr4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=VP5alzeZ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="VP5alzeZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3040E1F000E9; Tue, 21 Jul 2026 18:51:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784659897; bh=dvhXn8ZK334Zt0cwjmiiD8srz5VNL+pH7nirwEJaivo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=VP5alzeZ3SYuQcpkcUgdKyX4HhZvmzTTCGMun5Z56PJUuZv22Wn2rFtwHPscyQaK/ UMLgo/BzM3vS0Y7pLqHlmKo3chZjqWfi2Id1tr5ywsmapKVvpZOCl2hNlPRpZH9/Jp syuPQoSUI+PrkydHTxf+geXEduS4OD7lU94ifLek= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 7.1 0773/2077] netfilter: nf_dup_netdev: add nf_dev_xmit_recursion*() helpers and use them Date: Tue, 21 Jul 2026 17:07:26 +0200 Message-ID: <20260721152611.027253167@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152552.646164743@linuxfoundation.org> References: <20260721152552.646164743@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pablo Neira Ayuso [ Upstream commit 2354e975932dabb06fad239f07a3b68fd1809737 ] Update nft_dup and nft_fwd to use the nf_dev_xmit_recursion() helpers. This patch also disables BH when transmitting the skb to address a possible migration to different CPU leading to imbalanced decrementation of the recursion counters. This is modeled after Florian Westphal's dev_xmit_recursion*() API available since commit 97cdcf37b57e ("net: place xmit recursion in softnet data") according to its current state in the tree. Fixes: 1d47b55b36d2 ("netfilter: nft_fwd_netdev: use recursion counter in neigh egress path") Fixes: f37ad9127039 ("netfilter: nf_dup_netdev: Move the recursion counter struct netdev_xmit") Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- include/net/netfilter/nf_dup_netdev.h | 34 +++++++++++++++++++++++---- net/netfilter/nf_dup_netdev.c | 15 ++++++------ net/netfilter/nft_fwd_netdev.c | 17 ++++++++------ 3 files changed, 47 insertions(+), 19 deletions(-) diff --git a/include/net/netfilter/nf_dup_netdev.h b/include/net/netfilter/nf_dup_netdev.h index 609bcf422a9b31..f6b05bd80c3fe3 100644 --- a/include/net/netfilter/nf_dup_netdev.h +++ b/include/net/netfilter/nf_dup_netdev.h @@ -11,15 +11,39 @@ 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); +static inline bool nf_dev_xmit_recursion(void) +{ + return unlikely(__this_cpu_read(softnet_data.xmit.nf_dup_skb_recursion) > + NF_RECURSION_LIMIT); +} + +static inline void nf_dev_xmit_recursion_inc(void) +{ + __this_cpu_inc(softnet_data.xmit.nf_dup_skb_recursion); +} + +static inline void nf_dev_xmit_recursion_dec(void) +{ + __this_cpu_dec(softnet_data.xmit.nf_dup_skb_recursion); +} #else - return ¤t->net_xmit.nf_dup_skb_recursion; -#endif +static inline bool nf_dev_xmit_recursion(void) +{ + return unlikely(current->net_xmit.nf_dup_skb_recursion > NF_RECURSION_LIMIT); +} + +static inline void nf_dev_xmit_recursion_inc(void) +{ + current->net_xmit.nf_dup_skb_recursion++; } +static inline void nf_dev_xmit_recursion_dec(void) +{ + current->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 3d88ef927f31cb..c6bd5c29bed66d 100644 --- a/net/netfilter/nf_dup_netdev.c +++ b/net/netfilter/nf_dup_netdev.c @@ -16,11 +16,6 @@ static void nf_do_netdev_egress(struct sk_buff *skb, struct net_device *dev, enum nf_dev_hooks hook) { - u8 *nf_dup_skb_recursion = nf_get_nf_dup_skb_recursion(); - - if (*nf_dup_skb_recursion > NF_RECURSION_LIMIT) - goto err; - if (hook == NF_NETDEV_INGRESS && skb_mac_header_was_set(skb)) { if (skb_cow_head(skb, skb->mac_len)) goto err; @@ -30,9 +25,15 @@ static void nf_do_netdev_egress(struct sk_buff *skb, struct net_device *dev, skb->dev = dev; skb_clear_tstamp(skb); - (*nf_dup_skb_recursion)++; + local_bh_disable(); + if (nf_dev_xmit_recursion()) { + local_bh_enable(); + goto err; + } + nf_dev_xmit_recursion_inc(); dev_queue_xmit(skb); - (*nf_dup_skb_recursion)--; + nf_dev_xmit_recursion_dec(); + local_bh_enable(); return; err: kfree_skb(skb); diff --git a/net/netfilter/nft_fwd_netdev.c b/net/netfilter/nft_fwd_netdev.c index b9e88d7cf3081a..a48c2f765bbaad 100644 --- a/net/netfilter/nft_fwd_netdev.c +++ b/net/netfilter/nft_fwd_netdev.c @@ -95,7 +95,6 @@ static void nft_fwd_neigh_eval(const struct nft_expr *expr, struct nft_regs *regs, const struct nft_pktinfo *pkt) { - u8 *nf_dup_skb_recursion = nf_get_nf_dup_skb_recursion(); struct nft_fwd_neigh *priv = nft_expr_priv(expr); void *addr = ®s->data[priv->sreg_addr]; int oif = regs->data[priv->sreg_dev]; @@ -154,13 +153,15 @@ static void nft_fwd_neigh_eval(const struct nft_expr *expr, goto out; } - if (*nf_dup_skb_recursion > NF_RECURSION_LIMIT) { + dev = dev_get_by_index_rcu(nft_net(pkt), oif); + if (!dev) { verdict = NF_DROP; goto out; } - dev = dev_get_by_index_rcu(nft_net(pkt), oif); - if (dev == NULL) { + local_bh_disable(); + if (nf_dev_xmit_recursion()) { + local_bh_enable(); verdict = NF_DROP; goto out; } @@ -169,16 +170,18 @@ static void nft_fwd_neigh_eval(const struct nft_expr *expr, if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { skb = skb_expand_head(skb, hh_len); if (!skb) { - verdict = NF_STOLEN; + local_bh_enable(); goto out; } } skb->dev = dev; skb_clear_tstamp(skb); - (*nf_dup_skb_recursion)++; + + nf_dev_xmit_recursion_inc(); neigh_xmit(neigh_table, dev, addr, skb); - (*nf_dup_skb_recursion)--; + nf_dev_xmit_recursion_dec(); + local_bh_enable(); out: regs->verdict.code = verdict; } -- 2.53.0