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 847F42C158A; Wed, 10 Jun 2026 16:16:36 +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=1781108198; cv=none; b=Kme4LwqCaYIj7nJW3V4KTpvp/mdaQqOocFhFqu6uTaFxO1FNdku/BkMM5InY4Si0RpmTvvQfqYDkpNC+Uw+kE+aNB5JBjeIBOhr/TO8SNEg1sFivpor6HT5PPy7dergl/wJOgSL/9xVza5Y+8ZlJ043CTP/IUntkqNfkiWbPm6I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781108198; c=relaxed/simple; bh=eUs6aE/X6PjMmZ8GhdCffdgajOxGWiaw9AWn9FdekXY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kcOrTyYX0TNG/BvA15ZyyJmQ+8cjG0t19o7FO1ugHyH85+YYS3K0j678VdE2HEa5L15HMW/G+UH7/WKe8LEdB3SmWWOOuSjLkIu56wKeEWi22dW9/Zliqlf96M1Szi7oHKJkYYdZQffEYyi3j7SdO0X4Gn7MumlTX8Cer1yliuM= 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=L9eW19wK; 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="L9eW19wK" Received: from localhost.localdomain (mail-agni [217.70.190.124]) by mail.netfilter.org (Postfix) with ESMTPSA id 59956601BC; Wed, 10 Jun 2026 18:16:34 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org; s=2025; t=1781108194; bh=1M/9winQCUlkug/E+s/WMieHPIsWBkxRusyhtgRtDPk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L9eW19wKjbqXPm9+ULMaoBG/h7qlhce0HY+d5r0ZmZkEGpvvcmywjobc+2nrTDlBp kPupxlbDkandWtE8ousyzctJJPrUZalH4iNcKfbhFjkWthk1CvF4c4QJ/l8yQzS8Y/ r0OSVKV9+FtR7dt+aetZOC9yn32S6fgb5QEbRLJZ+3YuAyAVIX8MV8Z2U4caSC6bZw 4DtSU+FFBchYE4Qbi4cEb71MGiHzSlSiwV8TOtvZuHVk1RuxDbyEelRM9jJgThlcur SqegobByk1LgAFxAVQxkrZssItWPNtdKRRmYTpZi6UQ4E8ZxAXIAv76VrtcgLZoXYU R3NxawqFhXpRA== 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 1/8] netfilter: revalidate bridge ports Date: Wed, 10 Jun 2026 18:16:21 +0200 Message-ID: <20260610161629.214092-2-pablo@netfilter.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260610161629.214092-1-pablo@netfilter.org> References: <20260610161629.214092-1-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: Florian Westphal ebt_redirect_tg() dereferences br_port_get_rcu() return without a NULL check, causing a kernel panic when the bridge port has been removed between the original hook invocation and an NFQUEUE reinject. A mere NULL check isn't sufficient, however. As sashiko review points out userspace can not only remove the port from the bridge, it could also place the device in a different virtual device, e.g. macvlan. If this happens, we must drop the packet, there is no way for us to reinject it into the bridge path. Switch to _upper API, we don't need the bridge port structure. Also, this fix keeps another bug intact: Both nfnetlink_log and nfnetlink_queue use CONFIG_BRIDGE_NETFILTER too aggressive, which prevents certain logging features when queueing in bridge family: NETFILTER_FAMILY_BRIDGE can be enabled while the old CONFIG_BRIDGE_NETFILTER cruft is off. Fixes tag is a common ancestor, this was always broken. Fixes: f350a0a87374 ("bridge: use rx_handler_data pointer to store net_bridge_port pointer") Reported-by: Ji'an Zhou Assisted-by: Claude:claude-sonnet-4-6 Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/bridge/netfilter/ebt_dnat.c | 4 +- net/bridge/netfilter/ebt_redirect.c | 16 +++++--- net/netfilter/nfnetlink_log.c | 23 +++++++++-- net/netfilter/nfnetlink_queue.c | 64 +++++++++++++++++++++++++---- 4 files changed, 89 insertions(+), 18 deletions(-) diff --git a/net/bridge/netfilter/ebt_dnat.c b/net/bridge/netfilter/ebt_dnat.c index 3fda71a8579d..73f185cccd63 100644 --- a/net/bridge/netfilter/ebt_dnat.c +++ b/net/bridge/netfilter/ebt_dnat.c @@ -39,7 +39,9 @@ ebt_dnat_tg(struct sk_buff *skb, const struct xt_action_param *par) dev = xt_in(par); break; case NF_BR_PRE_ROUTING: - dev = br_port_get_rcu(xt_in(par))->br->dev; + dev = netdev_master_upper_dev_get_rcu(xt_in(par)); + if (!dev) /* bridge port removed? */ + return EBT_DROP; break; default: dev = NULL; diff --git a/net/bridge/netfilter/ebt_redirect.c b/net/bridge/netfilter/ebt_redirect.c index 307790562b49..83486cd4d564 100644 --- a/net/bridge/netfilter/ebt_redirect.c +++ b/net/bridge/netfilter/ebt_redirect.c @@ -24,12 +24,18 @@ ebt_redirect_tg(struct sk_buff *skb, const struct xt_action_param *par) if (skb_ensure_writable(skb, 0)) return EBT_DROP; - if (xt_hooknum(par) != NF_BR_BROUTING) - /* rcu_read_lock()ed by nf_hook_thresh */ - ether_addr_copy(eth_hdr(skb)->h_dest, - br_port_get_rcu(xt_in(par))->br->dev->dev_addr); - else + if (xt_hooknum(par) != NF_BR_BROUTING) { + const struct net_device *dev; + + dev = netdev_master_upper_dev_get_rcu(xt_in(par)); + if (!dev) + return EBT_DROP; + + ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr); + } else { ether_addr_copy(eth_hdr(skb)->h_dest, xt_in(par)->dev_addr); + } + skb->pkt_type = PACKET_HOST; return info->target; } diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c index 2439cbbd5b26..fa3657599861 100644 --- a/net/netfilter/nfnetlink_log.c +++ b/net/netfilter/nfnetlink_log.c @@ -451,6 +451,23 @@ static int nfulnl_put_bridge(struct nfulnl_instance *inst, const struct sk_buff return -1; } +#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) +static int nflog_put_master_ifindex(struct sk_buff *nlskb, int attr, + const struct net_device *dev) +{ + const struct net_device *upper; + + if (dev && !netif_is_bridge_port(dev)) + return 0; + + upper = netdev_master_upper_dev_get_rcu((struct net_device *)dev); + if (upper && nla_put_be32(nlskb, attr, htonl(upper->ifindex))) + return -EMSGSIZE; + + return 0; +} +#endif + /* This is an inline function, we don't really care about a long * list of arguments */ static inline int @@ -505,8 +522,7 @@ __build_packet_message(struct nfnl_log_net *log, /* rcu_read_lock()ed by nf_hook_thresh or * nf_log_packet. */ - nla_put_be32(inst->skb, NFULA_IFINDEX_INDEV, - htonl(br_port_get_rcu(indev)->br->dev->ifindex))) + nflog_put_master_ifindex(inst->skb, NFULA_IFINDEX_INDEV, indev)) goto nla_put_failure; } else { int physinif; @@ -542,8 +558,7 @@ __build_packet_message(struct nfnl_log_net *log, /* rcu_read_lock()ed by nf_hook_thresh or * nf_log_packet. */ - nla_put_be32(inst->skb, NFULA_IFINDEX_OUTDEV, - htonl(br_port_get_rcu(outdev)->br->dev->ifindex))) + nflog_put_master_ifindex(inst->skb, NFULA_IFINDEX_OUTDEV, outdev)) goto nla_put_failure; } else { struct net_device *physoutdev; diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c index 60ab88d45096..c5e29fec419b 100644 --- a/net/netfilter/nfnetlink_queue.c +++ b/net/netfilter/nfnetlink_queue.c @@ -440,10 +440,47 @@ static bool nf_ct_drop_unconfirmed(const struct nf_queue_entry *entry, bool *is_ return false; } +static bool nf_bridge_port_valid(const struct net_device *dev) +{ + if (!dev) + return true; + + return netif_is_bridge_port(dev); +} + +/* queued skbs leave rcu protection. We bump device refcount so that + * the device cannot go away. However, while packet was out the port + * could have been removed from the bridge. + * + * Ensure in+outdev are still part of a bridge at reinject time. + * + * The device rx_handler_data could even be pointing at data that is + * not a net_bridge_port structure. + */ +static bool nf_bridge_ports_valid(const struct nf_queue_entry *entry) +{ +#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) + if (!nf_bridge_port_valid(entry->physin) || + !nf_bridge_port_valid(entry->physout)) + return false; +#endif + if (entry->state.pf != PF_BRIDGE) + return true; + + if (!nf_bridge_port_valid(entry->state.in) || + !nf_bridge_port_valid(entry->state.out)) + return false; + + return true; +} + static void nfqnl_reinject(struct nf_queue_entry *entry, unsigned int verdict) { const struct nf_ct_hook *ct_hook; + if (!nf_bridge_ports_valid(entry)) + verdict = NF_DROP; + if (verdict == NF_ACCEPT || verdict == NF_REPEAT || verdict == NF_STOP) { @@ -636,6 +673,23 @@ static int nf_queue_checksum_help(struct sk_buff *entskb) return skb_checksum_help(entskb); } +#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) +static int nfqnl_put_master_ifindex(struct sk_buff *nlskb, int attr, + const struct net_device *dev) +{ + const struct net_device *upper; + + if (dev && !netif_is_bridge_port(dev)) + return 0; + + upper = netdev_master_upper_dev_get_rcu((struct net_device *)dev); + if (upper && nla_put_be32(nlskb, attr, htonl(upper->ifindex))) + return -EMSGSIZE; + + return 0; +} +#endif + static struct sk_buff * nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue, struct nf_queue_entry *entry, @@ -771,10 +825,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue, * netfilter_bridge) */ if (nla_put_be32(skb, NFQA_IFINDEX_PHYSINDEV, htonl(indev->ifindex)) || - /* this is the bridge group "brX" */ - /* rcu_read_lock()ed by __nf_queue */ - nla_put_be32(skb, NFQA_IFINDEX_INDEV, - htonl(br_port_get_rcu(indev)->br->dev->ifindex))) + nfqnl_put_master_ifindex(skb, NFQA_IFINDEX_INDEV, indev)) goto nla_put_failure; } else { int physinif; @@ -805,10 +856,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue, * netfilter_bridge) */ if (nla_put_be32(skb, NFQA_IFINDEX_PHYSOUTDEV, htonl(outdev->ifindex)) || - /* this is the bridge group "brX" */ - /* rcu_read_lock()ed by __nf_queue */ - nla_put_be32(skb, NFQA_IFINDEX_OUTDEV, - htonl(br_port_get_rcu(outdev)->br->dev->ifindex))) + nfqnl_put_master_ifindex(skb, NFQA_IFINDEX_OUTDEV, outdev)) goto nla_put_failure; } else { int physoutif; -- 2.47.3