[ovs-dev] [PATCH V4 18/24] datapath: support asymmetric conntrack

[Greg Rose]

From: aaron conole <aconole at redhat.com>

Upstream commit:
    commit 5d50aa83e2c8e91ced2cca77c198b468ca9210f4
    author: aaron conole <aconole at redhat.com>
    date:   tue dec 3 16:34:13 2019 -0500

    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 at redhat.com>
    signed-off-by: david s. miller <davem at davemloft.net>

Fixes: c5f6c06b58d6 ("datapath: Interface with NAT.")
Cc: aaron conole <aconole at redhat.com>
Acked-by: Aaron Conole <aconole at redhat.com>
Signed-off-by: Greg Rose <gvrose8192 at gmail.com>
---
 datapath/conntrack.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/datapath/conntrack.c b/datapath/conntrack.c
index 5b4d6cce0..c7a318baf 100644
--- a/datapath/conntrack.c
+++ b/datapath/conntrack.c
@@ -978,6 +978,17 @@ 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);
-- 
2.17.1