From patchwork Wed Oct 7 19:32:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Francesco Ruggeri X-Patchwork-Id: 1378248 X-Patchwork-Delegate: pablo@netfilter.org Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netfilter-devel-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=arista.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=arista.com header.i=@arista.com header.a=rsa-sha256 header.s=Arista-A header.b=mXoD2Q+n; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4C64HZ4r55z9sSG for ; Thu, 8 Oct 2020 06:32:58 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727858AbgJGTcx (ORCPT ); Wed, 7 Oct 2020 15:32:53 -0400 Received: from mx.aristanetworks.com ([162.210.129.12]:28723 "EHLO smtp.aristanetworks.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726129AbgJGTcx (ORCPT ); Wed, 7 Oct 2020 15:32:53 -0400 Received: from us180.sjc.aristanetworks.com (us180.sjc.aristanetworks.com [10.243.128.7]) by smtp.aristanetworks.com (Postfix) with ESMTP id 925304000A4; Wed, 7 Oct 2020 12:32:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=Arista-A; t=1602099172; bh=C0+5yjcysMk84GoYj0z05bOXjUBeWKhioIraoOaj5pU=; h=Date:To:Subject:From:From; b=mXoD2Q+nkriF0p709lff2+rKBzk1REnY4s8WWlfDsdp8XssJvXd27weNqnsFx5/U/ sRUi67pxVPh5Y1O4b2/L1D+zOL9gmM86BSOv1xl5badSNO8lnSusEz9+dTETDN/B2P yDPwY0lve2/jTMyBTnHwZM2B3zQZ1yFqXPIE+Q458cvvJ+bWR0ZKcN8LvQTzqSDKl9 c8HjBTU+6M9Ifi9cVezxItw69tTl98ScyOuKIrXsD0rOAjhqdMPRjsWLzgrg449rob BLG0t3+vLnLsM8/zxfEgRo1tDe4Sahgq6xzk7LYcqIq14UeYcigAnEkAUCMGKhDceW 7zhhKeaxmY6cQ== Received: by us180.sjc.aristanetworks.com (Postfix, from userid 10189) id 7009D95C169C; Wed, 7 Oct 2020 12:32:52 -0700 (PDT) Date: Wed, 07 Oct 2020 12:32:52 -0700 To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, coreteam@netfilter.org, netfilter-devel@vger.kernel.org, kuba@kernel.org, davem@davemloft.net, fw@strlen.org, kadlec@netfilter.org, pablo@netfilter.org, fruggeri@arista.com Subject: [PATCH nf v2] netfilter: conntrack: connection timeout after re-register User-Agent: Heirloom mailx 12.5 7/5/10 Message-Id: <20201007193252.7009D95C169C@us180.sjc.aristanetworks.com> From: fruggeri@arista.com (Francesco Ruggeri) Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org If the first packet conntrack sees after a re-register is an outgoing keepalive packet with no data (SEG.SEQ = SND.NXT-1), td_end is set to SND.NXT-1. When the peer correctly acknowledges SND.NXT, tcp_in_window fails check III (Upper bound for valid (s)ack: sack <= receiver.td_end) and returns false, which cascades into nf_conntrack_in setting skb->_nfct = 0 and in later conntrack iptables rules not matching. In cases where iptables are dropping packets that do not match conntrack rules this can result in idle tcp connections to time out. v2: adjust td_end when getting the reply rather than when sending out the keepalive packet. Fixes: f94e63801ab2 ("netfilter: conntrack: reset tcp maxwin on re-register") Signed-off-by: Francesco Ruggeri --- net/netfilter/nf_conntrack_proto_tcp.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c index e8c86ee4c1c4..c8fb2187ad4b 100644 --- a/net/netfilter/nf_conntrack_proto_tcp.c +++ b/net/netfilter/nf_conntrack_proto_tcp.c @@ -541,13 +541,20 @@ static bool tcp_in_window(const struct nf_conn *ct, swin = win << sender->td_scale; sender->td_maxwin = (swin == 0 ? 1 : swin); sender->td_maxend = end + sender->td_maxwin; - /* - * We haven't seen traffic in the other direction yet - * but we have to tweak window tracking to pass III - * and IV until that happens. - */ - if (receiver->td_maxwin == 0) + if (receiver->td_maxwin == 0) { + /* We haven't seen traffic in the other + * direction yet but we have to tweak window + * tracking to pass III and IV until that + * happens. + */ receiver->td_end = receiver->td_maxend = sack; + } else if (sack == receiver->td_end + 1) { + /* Likely a reply to a keepalive. + * Needed for III. + */ + receiver->td_end++; + } + } } else if (((state->state == TCP_CONNTRACK_SYN_SENT && dir == IP_CT_DIR_ORIGINAL)