From patchwork Fri Apr 14 21:26:38 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jarno Rajahalme X-Patchwork-Id: 750962 X-Patchwork-Delegate: pablo@netfilter.org Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3w4W266S8cz9s80 for ; Sat, 15 Apr 2017 07:26:54 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752152AbdDNV0y (ORCPT ); Fri, 14 Apr 2017 17:26:54 -0400 Received: from relay2-d.mail.gandi.net ([217.70.183.194]:45126 "EHLO relay2-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751830AbdDNV0x (ORCPT ); Fri, 14 Apr 2017 17:26:53 -0400 Received: from mfilter11-d.gandi.net (mfilter11-d.gandi.net [217.70.178.131]) by relay2-d.mail.gandi.net (Postfix) with ESMTP id 1C370C5A5A; Fri, 14 Apr 2017 23:26:52 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at mfilter11-d.gandi.net Received: from relay2-d.mail.gandi.net ([IPv6:::ffff:217.70.183.194]) by mfilter11-d.gandi.net (mfilter11-d.gandi.net [::ffff:10.0.15.180]) (amavisd-new, port 10024) with ESMTP id rdqpgmfI6btb; Fri, 14 Apr 2017 23:26:50 +0200 (CEST) X-Originating-IP: 208.91.1.34 Received: from sc9-mailhost1.vmware.com (unknown [208.91.1.34]) (Authenticated sender: jarno@ovn.org) by relay2-d.mail.gandi.net (Postfix) with ESMTPSA id 93546C5A67; Fri, 14 Apr 2017 23:26:49 +0200 (CEST) From: Jarno Rajahalme To: netfilter-devel@vger.kernel.org Cc: jarno@ovn.org, joe@ovn.org Subject: [PATCH nf v3] net/openvswitch: Delete conntrack entry clashing with an expectation. Date: Fri, 14 Apr 2017 14:26:38 -0700 Message-Id: <1492205198-41758-1-git-send-email-jarno@ovn.org> X-Mailer: git-send-email 2.1.4 Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Conntrack helpers do not check for a potentially clashing conntrack entry when creating a new expectation. Also, nf_conntrack_in() will check expectations (via init_conntrack()) only if a conntrack entry can not be found. The expectation for a packet which also matches an existing conntrack entry will not be removed by conntrack, and is currently handled inconsistently by OVS, as OVS expects the expectation to be removed when the connection tracking entry matching that expectation is confirmed. It should be noted that normally an IP stack would not allow reuse of a 5-tuple of an old (possibly lingering) connection for a new data connection, so this is somewhat unlikely corner case. However, it is possible that a misbehaving source could cause conntrack entries be created that could then interfere with new related connections. Fix this in the OVS module by deleting the clashing conntrack entry after an expectation has been matched. This causes the following nf_conntrack_in() call also find the expectation and remove it when creating the new conntrack entry, as well as the forthcoming reply direction packets to match the new related connection instead of the old clashing conntrack entry. Fixes: 7f8a436eaa2c ("openvswitch: Add conntrack action") Reported-by: Yang Song Signed-off-by: Jarno Rajahalme Acked-by: Joe Stringer --- v3: Removed unnecessary if statement. v2: Fixed commit title. net/openvswitch/conntrack.c | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c index 7b2c2fc..d796ae7 100644 --- a/net/openvswitch/conntrack.c +++ b/net/openvswitch/conntrack.c @@ -514,10 +514,39 @@ ovs_ct_expect_find(struct net *net, const struct nf_conntrack_zone *zone, u16 proto, const struct sk_buff *skb) { struct nf_conntrack_tuple tuple; + struct nf_conntrack_expect *exp; if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb), proto, net, &tuple)) return NULL; - return __nf_ct_expect_find(net, zone, &tuple); + + exp = __nf_ct_expect_find(net, zone, &tuple); + + if (exp) { + struct nf_conntrack_tuple_hash *h; + + /* Delete existing conntrack entry, if it clashes with the + * expectation. This can happen since conntrack ALGs do not + * check for clashes between (new) expectations and existing + * conntrack entries. nf_conntrack_in() will check the + * expectations only if a conntrack entry can not be found, + * which can lead to OVS finding the expectation (here) in the + * init direction, but which will not be removed by the + * nf_conntrack_in() call, if a matching conntrack entry is + * found instead. In this case all init direction packets + * would be reported as new related packets, while reply + * direction packets would be reported as un-related + * established packets. */ + + h = nf_conntrack_find_get(net, zone, &tuple); + if (h) { + struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h); + + nf_ct_delete(ct, 0, 0); + nf_conntrack_put(&ct->ct_general); + } + } + + return exp; } /* This replicates logic from nf_conntrack_core.c that is not exported. */