From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Date: Wed, 9 Jun 2021 11:23:56 -0300
Subject: net/sched: act_ct: handle DNAT tuple collision
Patch-mainline: v5.13-rc7
Git-commit: 13c62f5371e3eb4fc3400cfa26e64ca75f888008
References: bsc#1154353

This this the counterpart of 8aa7b526dc0b ("openvswitch: handle DNAT
tuple collision") for act_ct. From that commit changelog:

"""
With multiple DNAT rules it's possible that after destination
translation the resulting tuples collide.

...

Netfilter handles this case by allocating a null binding for SNAT at
egress by default.  Perform the same operation in openvswitch for DNAT
if no explicit SNAT is requested by the user and allocate a null binding
for SNAT for packets in the "original" direction.
"""

Fixes: 95219afbb980 ("act_ct: support asymmetric conntrack")
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/sched/act_ct.c |   19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -361,14 +361,19 @@ static int tcf_ct_act_nat(struct sk_buff
 	}
 
 	err = ct_nat_execute(skb, ct, ctinfo, 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;
+	if (err == NF_ACCEPT && ct->status & IPS_DST_NAT) {
+		if (ct->status & IPS_SRC_NAT) {
+			if (maniptype == NF_NAT_MANIP_SRC)
+				maniptype = NF_NAT_MANIP_DST;
+			else
+				maniptype = NF_NAT_MANIP_SRC;
 
-		err = ct_nat_execute(skb, ct, ctinfo, range, maniptype);
+			err = ct_nat_execute(skb, ct, ctinfo, range,
+					     maniptype);
+		} else if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
+			err = ct_nat_execute(skb, ct, ctinfo, NULL,
+					     NF_NAT_MANIP_SRC);
+		}
 	}
 	return err;
 #else