From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED19CC636CC for ; Tue, 31 Jan 2023 10:42:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229693AbjAaKmu (ORCPT ); Tue, 31 Jan 2023 05:42:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229661AbjAaKmu (ORCPT ); Tue, 31 Jan 2023 05:42:50 -0500 Received: from mail.netfilter.org (mail.netfilter.org [217.70.188.207]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 2FBDF7EC1 for ; Tue, 31 Jan 2023 02:42:49 -0800 (PST) Date: Tue, 31 Jan 2023 11:42:43 +0100 From: Pablo Neira Ayuso To: Florian Westphal Cc: netfilter-devel , Wolfgang Nothdurft Subject: Re: [PATCH nf] netfilter: br_netfilter: disable sabotage_in hook after first suppression Message-ID: References: <20230130103929.66551-1-fw@strlen.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230130103929.66551-1-fw@strlen.de> Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On Mon, Jan 30, 2023 at 11:39:29AM +0100, Florian Westphal wrote: > When using a xfrm interface in a bridged setup (the outgoing device is > bridged), the incoming packets in the xfrm interface are only tracked > in the outgoing direction. > > $ brctl show > bridge name interfaces > br_eth1 eth1 > > $ conntrack -L > tcp 115 SYN_SENT src=192... dst=192... [UNREPLIED] ... > > If br_netfilter is enabled, the first (encrypted) packet is received onR > eth1, conntrack hooks are called from br_netfilter emulation which > allocates nf_bridge info for this skb. > > If the packet is for local machine, skb gets passed up the ip stack. > The skb passes through ip prerouting a second time. br_netfilter > ip_sabotage_in supresses the re-invocation of the hooks. > > After this, skb gets decrypted in xfrm layer and appears in > network stack a second time (after decyption). > > Then, ip_sabotage_in is called again and suppresses netfilter > hook invocation, even though the bridge layer never called them > for the plaintext incarnation of the packet. > > Free the bridge info after the first suppression to avoid this. I'll add this tag (just one sufficiently old): Fixes: c4b0e771f906 ("netfilter: avoid using skb->nf_bridge directly") unless you prefer anything else. Let me know, thanks. > Reported-and-tested-by: Wolfgang Nothdurft > Signed-off-by: Florian Westphal > --- > net/bridge/br_netfilter_hooks.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c > index f20f4373ff40..9554abcfd5b4 100644 > --- a/net/bridge/br_netfilter_hooks.c > +++ b/net/bridge/br_netfilter_hooks.c > @@ -871,6 +871,7 @@ static unsigned int ip_sabotage_in(void *priv, > if (nf_bridge && !nf_bridge->in_prerouting && > !netif_is_l3_master(skb->dev) && > !netif_is_l3_slave(skb->dev)) { > + nf_bridge_info_free(skb); > state->okfn(state->net, state->sk, skb); > return NF_STOLEN; > } > -- > 2.39.1 >