linux-kernel - [PATCH 5.3 10/25] openvswitch: support asymmetric conntrack

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Date:   Tue, 17 Dec 2019 21:16:09 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Aaron Conole <aconole@...hat.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.3 10/25] openvswitch: support asymmetric conntrack

From: Aaron Conole <aconole@...hat.com>

[ Upstream commit 5d50aa83e2c8e91ced2cca77c198b468ca9210f4 ]

The openvswitch module shares a common conntrack and NAT infrastructure
exposed via netfilter.  It's possible that a packet needs both SNAT and
DNAT manipulation, due to e.g. tuple collision.  Netfilter can support
this because it runs through the NAT table twice - once on ingress and
again after egress.  The openvswitch module doesn't have such capability.

Like netfilter hook infrastructure, we should run through NAT twice to
keep the symmetry.

Fixes: 05752523e565 ("openvswitch: Interface with NAT.")
Signed-off-by: Aaron Conole <aconole@...hat.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/openvswitch/conntrack.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -903,6 +903,17 @@ static int ovs_ct_nat(struct net *net, s
 	}
 	err = ovs_ct_nat_execute(skb, ct, ctinfo, &info->range, maniptype);
 
+	if (err == NF_ACCEPT &&
+	    ct->status & IPS_SRC_NAT && ct->status & IPS_DST_NAT) {
+		if (maniptype == NF_NAT_MANIP_SRC)
+			maniptype = NF_NAT_MANIP_DST;
+		else
+			maniptype = NF_NAT_MANIP_SRC;
+
+		err = ovs_ct_nat_execute(skb, ct, ctinfo, &info->range,
+					 maniptype);
+	}
+
 	/* Mark NAT done if successful and update the flow key. */
 	if (err == NF_ACCEPT)
 		ovs_nat_update_key(key, skb, maniptype);