From 8aa7b526dc0b5dbf40c1b834d76a667ad672a410 Mon Sep 17 00:00:00 2001
From: Dumitru Ceara <dceara@redhat.com>
Date: Wed, 7 Oct 2020 17:48:03 +0200
Subject: [PATCH] openvswitch: handle DNAT tuple collision
With multiple DNAT rules it's possible that after destination
translation the resulting tuples collide.
For example, two openvswitch flows:
nw_dst=10.0.0.10,tp_dst=10, actions=ct(commit,table=2,nat(dst=20.0.0.1:20))
nw_dst=10.0.0.20,tp_dst=10, actions=ct(commit,table=2,nat(dst=20.0.0.1:20))
Assuming two TCP clients initiating the following connections:
10.0.0.10:5000->10.0.0.10:10
10.0.0.10:5000->10.0.0.20:10
Both tuples would translate to 10.0.0.10:5000->20.0.0.1:20 causing
nf_conntrack_confirm() to fail because of tuple collision.
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.
Reported-at: https://bugzilla.redhat.com/1877128
Suggested-by: Florian Westphal <fw@strlen.de>
Fixes: 05752523e565 ("openvswitch: Interface with NAT.")
Signed-off-by: Dumitru Ceara <dceara@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
net/openvswitch/conntrack.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)
diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index a3f1204f1ed2..12d42ab0193b 100644
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -905,15 +905,19 @@ 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);
+ 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 = ovs_ct_nat_execute(skb, ct, ctinfo, &info->range,
+ maniptype);
+ } else if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
+ err = ovs_ct_nat_execute(skb, ct, ctinfo, NULL,
+ NF_NAT_MANIP_SRC);
+ }
}
/* Mark NAT done if successful and update the flow key. */
--
2.42.0