From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.netfilter.org (mail.netfilter.org [217.70.190.124]) (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 A33111DA60D; Mon, 1 Jun 2026 11:59:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.190.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780315176; cv=none; b=BARmjGL7Aw6OMFzf/gE4Pec8yWx6D4bgeLR/l8gGGwJ7/M49kroJeqcFQp5pCV9D9vpSLsmgqJ7CAsaI/nEWDXI3leJ4e7R8fkSel5tK8XtqiYTpHnF7turfKNmHq43aqGzVk2spMdaG5xqCNEFDyEDHjnXzI7dbJE4v0CIStIs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780315176; c=relaxed/simple; bh=gMryO+GUDj0Mrzn0TOtghewI2/kmcTwaBonfuN/0hCQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=X5V6rB3eZ9cC/rPzU+HD9Vw3yPCtmLZslTDP9Nech7sjvG67QdOUKNvyBoyQPiCrikZHcIPB6M9XTcm9oRdtUO5Nf69VC400SjKMG0VuPORWSuUOzU+NEAVu0Qf4OCQtBa4Skbpvtt7+s2cTRIQEaBVFGwltrIgIthnoQf37s0Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org; spf=pass smtp.mailfrom=netfilter.org; dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org header.b=GmvasXSf; arc=none smtp.client-ip=217.70.190.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=netfilter.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org header.b="GmvasXSf" Received: from localhost.localdomain (mail-agni [217.70.190.124]) by mail.netfilter.org (Postfix) with ESMTPSA id 0981D601A6; Mon, 1 Jun 2026 13:59:32 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org; s=2025; t=1780315173; bh=GBV7Izyq5SsFMiqD2t72nhYgYdmpWh2Cbiwtu6AddH0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GmvasXSfxS19ILtbGF+M1YUqsKc0/t0xiuaYAR7lWp4J3YhqAGamhIxzwXtiW7Jkl eDKbnIzRvD/mVJZcIwmz6YJxQNjQiItyzbkQ/6XATNSUw1JO/hCKiZgj70awv/UgKv PaSRxLR6L45R6YEHwz6pU8CXFqBtluopJAsX8rHnYmsRquCRmjpJl1TyZl8oo5c8ff Z12HRNBXgLgArAK6BWrG/TvoA8DYAPOFmMK4AOailmBVehkccHb75NmzvMcb4Z4pWv 3+I7zxtV2zo9TzyHFVLkSTR335K0ouSYrFRuXheuao79cxQSzaHza1PkiAEMiY95mF X7XzhLBc1TN4A== From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, fw@strlen.de, horms@kernel.org Subject: [PATCH net 4/9] netfilter: synproxy: add mutex to guard hook reference counting Date: Mon, 1 Jun 2026 13:59:18 +0200 Message-ID: <20260601115923.433946-5-pablo@netfilter.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260601115923.433946-1-pablo@netfilter.org> References: <20260601115923.433946-1-pablo@netfilter.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Fernando Fernandez Mancera As the synproxy infrastructure register netfilter hooks on-demand when a user adds the first iptables target or nftables expression, if done concurrently they can race each other. Introduce a mutex to serialize the refcount control blocks access from both frontends. While a per namespace mutex might be more efficient, it is not needed for target/expression like SYNPROXY. Fixes: ad49d86e07a4 ("netfilter: nf_tables: Add synproxy support") Signed-off-by: Fernando Fernandez Mancera Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_synproxy_core.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/net/netfilter/nf_synproxy_core.c b/net/netfilter/nf_synproxy_core.c index 036c8586f49b..ed00114f65f3 100644 --- a/net/netfilter/nf_synproxy_core.c +++ b/net/netfilter/nf_synproxy_core.c @@ -22,6 +22,8 @@ #include #include +static DEFINE_MUTEX(synproxy_mutex); + unsigned int synproxy_net_id; EXPORT_SYMBOL_GPL(synproxy_net_id); @@ -769,26 +771,31 @@ static const struct nf_hook_ops ipv4_synproxy_ops[] = { int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net) { - int err; + int err = 0; + mutex_lock(&synproxy_mutex); if (snet->hook_ref4 == 0) { err = nf_register_net_hooks(net, ipv4_synproxy_ops, ARRAY_SIZE(ipv4_synproxy_ops)); if (err) - return err; + goto out; } snet->hook_ref4++; - return 0; +out: + mutex_unlock(&synproxy_mutex); + return err; } EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_init); void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net) { + mutex_lock(&synproxy_mutex); snet->hook_ref4--; if (snet->hook_ref4 == 0) nf_unregister_net_hooks(net, ipv4_synproxy_ops, ARRAY_SIZE(ipv4_synproxy_ops)); + mutex_unlock(&synproxy_mutex); } EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_fini); @@ -1193,27 +1200,32 @@ static const struct nf_hook_ops ipv6_synproxy_ops[] = { int nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net) { - int err; + int err = 0; + mutex_lock(&synproxy_mutex); if (snet->hook_ref6 == 0) { err = nf_register_net_hooks(net, ipv6_synproxy_ops, ARRAY_SIZE(ipv6_synproxy_ops)); if (err) - return err; + goto out; } snet->hook_ref6++; - return 0; +out: + mutex_unlock(&synproxy_mutex); + return err; } EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_init); void nf_synproxy_ipv6_fini(struct synproxy_net *snet, struct net *net) { + mutex_lock(&synproxy_mutex); snet->hook_ref6--; if (snet->hook_ref6 == 0) nf_unregister_net_hooks(net, ipv6_synproxy_ops, ARRAY_SIZE(ipv6_synproxy_ops)); + mutex_unlock(&synproxy_mutex); } EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_fini); #endif /* CONFIG_IPV6 */ -- 2.47.3