Disable ARP/NA responders for vlan-passthru switches

When vlan-passthru is on, VIFs may attach different VLAN tags. In this
case, VIFs are not guaranteed to belong to the same L2 broadcast domain.
Because of that, we don't know if a peer port on the switch has the same
tag used and should not allow the local responder to generate neighbour
traffic. Instead, pass ARP and ND requests to the peer port owner and
allow it to reply, if needed.

Conflicts:
      northd/ovn_northd.dl

Signed-off-by: Ihar Hrachyshka <ihrachys@redhat.com>
Signed-off-by: Numan Siddique <numans@ovn.org>
Acked-by: Mark Michelson <mmichels@redhat.com>
(cherry picked from commit ea57f66)
(cherry picked from commit 0cfd85b)

northd/ovn-northd.8.xml

@@ -995,8 +995,10 @@ output;
           <code>localport</code> ports) that are down (unless <code>
           ignore_lsp_down</code> is configured as true in <code>options</code>
           column of <code>NB_Global</code> table of the <code>Northbound</code>
-          database), for logical ports of type <code>virtual</code> and for
-          logical ports with 'unknown' address set.
+          database), for logical ports of type <code>virtual</code>, for
+          logical ports with 'unknown' address set and for logical ports of
+          a logical switch configured with
+          <code>other_config:vlan-passthru=true</code>.
         </p>
       </li>
 

northd/ovn-northd.c

@@ -6936,6 +6936,10 @@ build_lswitch_arp_nd_responder_known_ips(struct ovn_port *op,
                 return;
             }
 
+            if (is_vlan_transparent(op->od)) {
+                return;
+            }
+
             for (size_t i = 0; i < op->n_lsp_addrs; i++) {
                 for (size_t j = 0; j < op->lsp_addrs[i].n_ipv4_addrs; j++) {
                     ds_clear(match);

tests/ovn.at

@@ -3155,6 +3155,118 @@ OVN_CLEANUP([hv-1],[hv-2])
 
 AT_CLEANUP
 
+OVN_FOR_EACH_NORTHD([
+AT_SETUP([ovn -- VLAN transparency, passthru=true, ARP responder disabled])
+ovn_start
+
+net_add net
+check ovs-vsctl add-br br-phys
+ovn_attach net br-phys 192.168.0.1
+
+check ovn-nbctl ls-add ls
+check ovn-nbctl --wait=sb add Logical-Switch ls other_config vlan-passthru=true
+
+for i in 1 2; do
+    check ovn-nbctl lsp-add ls lsp$i
+    check ovn-nbctl lsp-set-addresses lsp$i "f0:00:00:00:00:0$i 10.0.0.$i"
+done
+
+for i in 1 2; do
+    check ovs-vsctl add-port br-int vif$i -- set Interface vif$i external-ids:iface-id=lsp$i \
+                                  options:tx_pcap=vif$i-tx.pcap \
+                                  options:rxq_pcap=vif$i-rx.pcap \
+                                  ofport-request=$i
+done
+
+wait_for_ports_up
+
+ovn-sbctl dump-flows ls > lsflows
+AT_CAPTURE_FILE([lsflows])
+
+AT_CHECK([grep -w "ls_in_arp_rsp" lsflows | sort], [0], [dnl
+  table=16(ls_in_arp_rsp      ), priority=0    , match=(1), action=(next;)
+])
+
+test_arp() {
+    local inport=$1 outport=$2 sha=$3 spa=$4 tpa=$5 reply_ha=$6
+    tag=8100fefe
+    local request=ffffffffffff${sha}${tag}08060001080006040001${sha}${spa}ffffffffffff${tpa}
+    ovs-appctl netdev-dummy/receive vif$inport $request
+    echo $request >> $outport.expected
+
+    local reply=${sha}${reply_ha}${tag}08060001080006040002${reply_ha}${tpa}${sha}${spa}
+    ovs-appctl netdev-dummy/receive vif$outport $reply
+    echo $reply >> $inport.expected
+}
+
+test_arp 1 2 f00000000001 0a000001 0a000002 f00000000002
+test_arp 2 1 f00000000002 0a000002 0a000001 f00000000001
+
+for i in 1 2; do
+    OVN_CHECK_PACKETS([vif$i-tx.pcap], [$i.expected])
+done
+
+AT_CLEANUP
+])
+
+OVN_FOR_EACH_NORTHD([
+AT_SETUP([ovn -- VLAN transparency, passthru=true, ND/NA responder disabled])
+ovn_start
+
+net_add net
+check ovs-vsctl add-br br-phys
+ovn_attach net br-phys 192.168.0.1
+
+check ovn-nbctl ls-add ls
+check ovn-nbctl --wait=sb add Logical-Switch ls other_config vlan-passthru=true
+
+for i in 1 2; do
+    check ovn-nbctl lsp-add ls lsp$i
+    check ovn-nbctl lsp-set-addresses lsp$i "f0:00:00:00:00:0$i fe00::$i"
+done
+
+for i in 1 2; do
+    check ovs-vsctl add-port br-int vif$i -- set Interface vif$i external-ids:iface-id=lsp$i \
+                                  options:tx_pcap=vif$i-tx.pcap \
+                                  options:rxq_pcap=vif$i-rx.pcap \
+                                  ofport-request=$i
+done
+
+wait_for_ports_up
+
+ovn-sbctl dump-flows ls > lsflows
+AT_CAPTURE_FILE([lsflows])
+
+AT_CHECK([grep -w "ls_in_arp_rsp" lsflows | sort], [0], [dnl
+  table=16(ls_in_arp_rsp      ), priority=0    , match=(1), action=(next;)
+])
+
+test_nd_na() {
+    local inport=$1 outport=$2 sha=$3 spa=$4 tpa=$5 reply_ha=$6
+    tag=8100fefe
+    icmp_type=87
+    local request=ffffffffffff${sha}${tag}86dd6000000000183aff${spa}ff0200000000000000000001ff${tpa: -6}${icmp_type}007ea100000000${tpa}
+    ovs-appctl netdev-dummy/receive vif$inport $request
+    echo $request >> $outport.expected
+    echo $request
+
+    icmp_type=88
+    local reply=${sha}${reply_ha}${tag}86dd6000000000183aff${tpa}${spa}${icmp_type}003da540000000${tpa}
+    ovs-appctl netdev-dummy/receive vif$outport $reply
+    echo $reply >> $inport.expected
+    echo $reply
+}
+
+test_nd_na 1 2 f00000000001 fe000000000000000000000000000001 fe000000000000000000000000000002 f00000000002
+test_nd_na 2 1 f00000000002 fe000000000000000000000000000002 fe000000000000000000000000000001 f00000000001
+
+for i in 1 2; do
+    OVN_CHECK_PACKETS([vif$i-tx.pcap], [$i.expected])
+done
+
+AT_CLEANUP
+])
+
 OVN_FOR_EACH_NORTHD([
 AT_SETUP([ovn -- VLAN transparency, passthru=true, multiple hosts])
 ovn_start