linux-kernel - [PATCH 5.4 14/90] net/sched: act_ct: handle DNAT tuple collision

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Date:   Mon, 21 Jun 2021 18:14:49 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 14/90] net/sched: act_ct: handle DNAT tuple collision

From: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>

[ Upstream commit 13c62f5371e3eb4fc3400cfa26e64ca75f888008 ]

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@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/sched/act_ct.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
index 31eb8eefc868..16c4cbf6d1f0 100644
--- 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 *skb,
 	}
 
 	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;
-
-		err = ct_nat_execute(skb, ct, ctinfo, range, maniptype);
+	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);
+		} else if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
+			err = ct_nat_execute(skb, ct, ctinfo, NULL,
+					     NF_NAT_MANIP_SRC);
+		}
 	}
 	return err;
 #else
-- 
2.30.2