From: Numan Siddique <num...@ovn.org>
Presently OVN assumes that an IPv6 Neigh Adv packet will have the
target link layer option preset. But that's not the case all the time.
This field is optional and as per rfc4861 (quoted below).
Target link-layer address
The link-layer address for the target, i.e., the
sender of the advertisement. This option MUST be
included on link layers that have addresses when
responding to multicast solicitations. When
responding to a unicast Neighbor Solicitation this
option SHOULD be included.
The option MUST be included for multicast
solicitations in order to avoid infinite Neighbor
Solicitation "recursion" when the peer node does
not have a cache entry to return a Neighbor
Advertisements message. When responding to unicast
solicitations, the option can be omitted since the
sender of the solicitation has the correct link-
layer address; otherwise, it would not be able to
send the unicast solicitation in the first place.
However, including the link-layer address in this
case adds little overhead and eliminates a
potential race condition where the sender deletes
the cached link-layer address prior to receiving a
response to a previous solicitation.
If target link layer option is not present, then ovn-controller learns
the mac binding with 00:00:00:00:00:00 address which is not correct.
This patch fixes the issue by adding the below logical flow in router
pipeline:
table=2 (lr_in_learn_neighbor), priority=95 , match=(nd_na && nd.tll == 0),
action=(put_nd(inport, nd.target, eth.src); next;)
Reported-at: https://bugzilla.redhat.com/show_bug.cgi?id=2078026
Signed-off-by: Numan Siddique <num...@ovn.org>
---
northd/northd.c | 6 ++++++
northd/ovn-northd.8.xml | 6 ++++++
tests/ovn-northd.at | 23 +++++++++++++++++++++++
3 files changed, 35 insertions(+)
diff --git a/northd/northd.c b/northd/northd.c
index bc195146d0..8c4187eae1 100644
--- a/northd/northd.c
+++ b/northd/northd.c
@@ -10943,6 +10943,12 @@ build_neigh_learning_flows_for_lrouter(
copp_meter_get(COPP_ARP, od->nbr->copp,
meter_groups));
+ ovn_lflow_metered(lflows, od, S_ROUTER_IN_LEARN_NEIGHBOR, 95,
+ "nd_na && nd.tll == 0",
+ "put_nd(inport, nd.target, eth.src); next;",
+ copp_meter_get(COPP_ND_NA, od->nbr->copp,
+ meter_groups));
+
ovn_lflow_metered(lflows, od, S_ROUTER_IN_LEARN_NEIGHBOR, 90,
"nd_na", "put_nd(inport, nd.target, nd.tll); next;",
copp_meter_get(COPP_ND_NA, od->nbr->copp,
diff --git a/northd/ovn-northd.8.xml b/northd/ovn-northd.8.xml
index db4f4d267c..d95e9c3fd2 100644
--- a/northd/ovn-northd.8.xml
+++ b/northd/ovn-northd.8.xml
@@ -2307,6 +2307,12 @@ next;
<code>put_arp(inport, arp.spa, arp.sha); next;</code>
</li>
+ <li>
+ A priority-95 flow with the match <code>nd_na &&
+ nd.tll == 0</code> and applies the action
+ <code>put_nd(inport, nd.target, eth.src); next;</code>
+ </li>
+
<li>
A priority-90 flow with the match <code>nd_na</code> and
applies the action
diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at
index adb3043853..163287edfa 100644
--- a/tests/ovn-northd.at
+++ b/tests/ovn-northd.at
@@ -6664,3 +6664,26 @@ ovn-nbctl --may-exist static-mac-binding-add lr0-p0
192.168.10.100 00:00:22:33:5
wait_row_count Static_MAC_Binding 1 logical_port=lr0-p0 ip=192.168.10.100
mac="00\:00\:22\:33\:55\:66"
AT_CLEANUP
+
+AT_SETUP([LR neighbor lookup and learning flows])
+ovn_start
+
+# Create logical routers
+ovn-nbctl --wait=sb lr-add lr0
+
+ovn-sbctl dump-flows lr0 > lrflows
+AT_CAPTURE_FILE([lrflows])
+
+AT_CHECK([cat lrflows | grep -e lr_in_lookup_neighbor -e lr_in_learn_neighbor
| sort], [0], [dnl
+ table=1 (lr_in_lookup_neighbor), priority=0 , match=(1),
action=(reg9[[2]] = 1; next;)
+ table=1 (lr_in_lookup_neighbor), priority=100 , match=(arp.op == 2),
action=(reg9[[2]] = lookup_arp(inport, arp.spa, arp.sha); next;)
+ table=1 (lr_in_lookup_neighbor), priority=100 , match=(nd_na),
action=(reg9[[2]] = lookup_nd(inport, nd.target, nd.tll); next;)
+ table=1 (lr_in_lookup_neighbor), priority=100 , match=(nd_ns),
action=(reg9[[2]] = lookup_nd(inport, ip6.src, nd.sll); next;)
+ table=2 (lr_in_learn_neighbor), priority=100 , match=(reg9[[2]] == 1),
action=(next;)
+ table=2 (lr_in_learn_neighbor), priority=90 , match=(arp),
action=(put_arp(inport, arp.spa, arp.sha); next;)
+ table=2 (lr_in_learn_neighbor), priority=90 , match=(nd_na),
action=(put_nd(inport, nd.target, nd.tll); next;)
+ table=2 (lr_in_learn_neighbor), priority=90 , match=(nd_ns),
action=(put_nd(inport, ip6.src, nd.sll); next;)
+ table=2 (lr_in_learn_neighbor), priority=95 , match=(nd_na && nd.tll ==
0), action=(put_nd(inport, nd.target, eth.src); next;)
+])
+
+AT_CLEANUP
--
2.35.1
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