From be5b458778abfc6dd3d30c0f520c77186935f9b2 Mon Sep 17 00:00:00 2001
From: Numan Siddique <numans@ovn.org>
Date: Tue, 19 Nov 2019 17:52:01 +0530
Subject: [PATCH 2/2] Skip IPv6 NS packets in router egress SNAT pipeline
When ovn-controller injects IPv6 NS packet to learn the mac, in some
setups it is observed that the packet is dropped by ovs-vswitchd. We see
below logs
2019-11-18T10:42:17.973Z|00001|ofproto_dpif_upcall(handler6)|INFO|received packet on unassociated datapath port 4294967295
2019-11-18T10:42:18.221Z|00001|ofproto_dpif_upcall(revalidator8)|WARN|Failed to acquire udpif_key corresponding to unexpected flow (Invalid argument): ufid:9ba1081f-a692-4c1c-a79b-d1cf04175f7d
Upon further debugging I noticed that, xlate_lookup() fails when there is upcall
from kernel datapath because of ct related actions. When ovn-controller injects
the packet it sets inport=CONTROLLER.
This patch addresses this issue by avoiding the IPv6 NS packets to be
sent to conntrack in the router egress pipeline.
This should be ideally fixed in ovs-vswitchd.
Reported-by: Russell Bryant <russell@ovn.org>
Signed-off-by: Numan Siddique <numans@ovn.org>
---
ovn/northd/ovn-northd.8.xml | 9 +++++++++
ovn/northd/ovn-northd.c | 5 +++++
2 files changed, 14 insertions(+)
diff --git a/ovn/northd/ovn-northd.8.xml b/ovn/northd/ovn-northd.8.xml
index 0fac02340..8f8fd5c01 100644
--- a/ovn/northd/ovn-northd.8.xml
+++ b/ovn/northd/ovn-northd.8.xml
@@ -2704,6 +2704,15 @@ nd_ns {
changed based on the configuration in the OVN Northbound database.
</p>
+ <ul>
+ <li>
+ A priority-120 flow to advance the IPv6 Neighbor solicitation packet
+ to next table to skip SNAT. In the case where ovn-controller injects
+ an IPv6 Neighbor Solicitation packet (for <code>nd_ns</code> action)
+ we don't want the packet to go throught conntrack.
+ </li>
+ </ul>
+
<p>Egress Table 1: SNAT on Gateway Routers</p>
<ul>
diff --git a/ovn/northd/ovn-northd.c b/ovn/northd/ovn-northd.c
index bcadcca3d..d94276b1e 100644
--- a/ovn/northd/ovn-northd.c
+++ b/ovn/northd/ovn-northd.c
@@ -7394,6 +7394,11 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
ovn_lflow_add(lflows, od, S_ROUTER_OUT_UNDNAT, 0, "1", "next;");
ovn_lflow_add(lflows, od, S_ROUTER_OUT_EGR_LOOP, 0, "1", "next;");
+ /* Send the IPv6 NS packets to next table. When ovn-controller
+ * generates IPv6 NS (for the action - nd_ns{}), the injected
+ * packet would go through conntrack - which is not required. */
+ ovn_lflow_add(lflows, od, S_ROUTER_OUT_SNAT, 120, "nd_ns", "next;");
+
/* NAT rules are only valid on Gateway routers and routers with
* l3dgw_port (router has a port with "redirect-chassis"
* specified). */
--
2.23.0