From: Dumitru Ceara <dceara@xxxxxxxxxx> commit 8aa7b526dc0b5dbf40c1b834d76a667ad672a410 upstream. 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@xxxxxxxxx> Fixes: 05752523e565 ("openvswitch: Interface with NAT.") Signed-off-by: Dumitru Ceara <dceara@xxxxxxxxxx> Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/openvswitch/conntrack.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) --- a/net/openvswitch/conntrack.c +++ b/net/openvswitch/conntrack.c @@ -899,15 +899,19 @@ static int ovs_ct_nat(struct net *net, s } 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; + 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); + 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. */
