[PATCH 5.12 031/178] net/sched: act_ct: handle DNAT tuple collision

Greg Kroah-Hartman
2021-06-21T16:38:37Z

From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.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@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.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 ba7f57cb41c3..143786d8cde0 100644
--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -904,14 +904,19 @@ 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