From: Dumitru Ceara dceara@redhat.com
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@strlen.de Fixes: 05752523e565 ("openvswitch: Interface with NAT.") Signed-off-by: Dumitru Ceara dceara@redhat.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.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 9bfe89ec6efd..90462f58e991 100644 --- a/net/openvswitch/conntrack.c +++ b/net/openvswitch/conntrack.c @@ -899,15 +899,19 @@ 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. */