netdev - [PATCH net 1/2] openvswitch: support asymmetric conntrack

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Message-Id: <20191108210714.12426-1-aconole@redhat.com>
Date:   Fri,  8 Nov 2019 16:07:13 -0500
From:   Aaron Conole <aconole@...hat.com>
To:     netdev@...r.kernel.org
Cc:     Pravin B Shelar <pshelar@....org>,
        "David S . Miller" <davem@...emloft.net>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>, dev@...nvswitch.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH net 1/2] openvswitch: support asymmetric conntrack

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>
---
 net/openvswitch/conntrack.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index 05249eb45082..283e8f9a5fd2 100644
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -903,6 +903,17 @@ static int ovs_ct_nat(struct net *net, struct sw_flow_key *key,
 	}
 	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);
-- 
2.21.0