From: Numan Siddique <[email protected]>

IPv6 Neigh Solicitation (NS) responder logical flows match on ip6.dst
field.  These flows when translated to datapath flows also match on
ip6.dst, which means a separate datapath flow per destination IP
address.  This may cause significant performance issues in some
setups (particularly ovs-dpdk telco deployments).

This patch addresses this issue by matching on eth.mcast6 so that
datapath flows for normal IPv6 traffic doesn't have to match on
ip6.dst.  IPv6 NS packets are generally multicast.  A new logical
match "nd_ns_mcast" for this purpose.

After this patch, We no longer respond to IPv6 NS unicast packets.
This behavior now matches the IPv4 ARP responder flows.  Note
that after the commit [1] which was recently added we now only
respond to IPv4 ARP broadcast packets.

A recent patch [2] from Ilya partially addressed the same datapath
flow explosion issue by matching on eth.mcast6 for MLD packets.
With this patch, we now completely address the datapath flow
explosion issue for IPv6 traffic provided all the logical ports
of a logical switch are not configured with port security.

[1] - c48ed1736a58 ("Do not reply on unicast arps for IPv4 targets.")
[2] - 43c34f2e6676 ("logical-fields: Add missing multicast matches for MLD and 
IGMP.")

Reported-at: https://issues.redhat.com/browse/FDP-728
Reported-by: Mike Pattrick <[email protected]>
Signed-off-by: Numan Siddique <[email protected]>
---
 lib/logical-fields.c |   3 ++
 northd/northd.c      |  11 ++--
 tests/ovn-northd.at  |   4 +-
 tests/ovn.at         |   2 +-
 tests/system-ovn.at  | 126 +++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 138 insertions(+), 8 deletions(-)

diff --git a/lib/logical-fields.c b/lib/logical-fields.c
index 2c9d3c61bf..f1ba1a7ac1 100644
--- a/lib/logical-fields.c
+++ b/lib/logical-fields.c
@@ -293,6 +293,9 @@ ovn_init_symtab(struct shash *symtab)
               "icmp6.type == {135, 136} && icmp6.code == 0 && ip.ttl == 255");
     expr_symtab_add_predicate(symtab, "nd_ns",
               "icmp6.type == 135 && icmp6.code == 0 && ip.ttl == 255");
+    expr_symtab_add_predicate(symtab, "nd_ns_mcast",
+              "eth.mcastv6 && icmp6.type == 135 && icmp6.code == 0 && "
+              "ip.ttl == 255");
     expr_symtab_add_predicate(symtab, "nd_na",
               "icmp6.type == 136 && icmp6.code == 0 && ip.ttl == 255");
     expr_symtab_add_predicate(symtab, "nd_rs",
diff --git a/northd/northd.c b/northd/northd.c
index 5ad30d854b..c0cda85e36 100644
--- a/northd/northd.c
+++ b/northd/northd.c
@@ -9638,11 +9638,12 @@ build_lswitch_arp_nd_responder_known_ips(struct 
ovn_port *op,
              * but always respond with the unicast IPv6 address. */
             for (size_t j = 0; j < op->lsp_addrs[i].n_ipv6_addrs; j++) {
                 ds_clear(match);
-                ds_put_format(match,
-                        "nd_ns && ip6.dst == {%s, %s} && nd.target == %s",
-                        op->lsp_addrs[i].ipv6_addrs[j].addr_s,
-                        op->lsp_addrs[i].ipv6_addrs[j].sn_addr_s,
-                        op->lsp_addrs[i].ipv6_addrs[j].addr_s);
+                ds_put_format(
+                    match,
+                    "nd_ns_mcast && ip6.dst == {%s, %s} && nd.target == %s",
+                    op->lsp_addrs[i].ipv6_addrs[j].addr_s,
+                    op->lsp_addrs[i].ipv6_addrs[j].sn_addr_s,
+                    op->lsp_addrs[i].ipv6_addrs[j].addr_s);
 
                 ds_clear(actions);
                 ds_put_format(actions,
diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at
index e4c8822656..509cfd2d30 100644
--- a/tests/ovn-northd.at
+++ b/tests/ovn-northd.at
@@ -9490,9 +9490,9 @@ AT_CAPTURE_FILE([S1flows])
 AT_CHECK([grep -e "ls_in_arp_rsp" S1flows | ovn_strip_lflows], [0], [dnl
   table=??(ls_in_arp_rsp      ), priority=0    , match=(1), action=(next;)
   table=??(ls_in_arp_rsp      ), priority=100  , match=(arp.tpa == 
192.168.0.10 && arp.op == 1 && eth.dst == ff:ff:ff:ff:ff:ff && inport == 
"S1-vm1"), action=(next;)
-  table=??(ls_in_arp_rsp      ), priority=100  , match=(nd_ns && ip6.dst == 
{fd00::10, ff02::1:ff00:10} && nd.target == fd00::10 && inport == "S1-vm1"), 
action=(next;)
+  table=??(ls_in_arp_rsp      ), priority=100  , match=(nd_ns_mcast && ip6.dst 
== {fd00::10, ff02::1:ff00:10} && nd.target == fd00::10 && inport == "S1-vm1"), 
action=(next;)
   table=??(ls_in_arp_rsp      ), priority=50   , match=(arp.tpa == 
192.168.0.10 && arp.op == 1 && eth.dst == ff:ff:ff:ff:ff:ff), action=(eth.dst = 
eth.src; eth.src = 50:54:00:00:00:10; arp.op = 2; /* ARP reply */ arp.tha = 
arp.sha; arp.sha = 50:54:00:00:00:10; arp.tpa = arp.spa; arp.spa = 
192.168.0.10; outport = inport; flags.loopback = 1; output;)
-  table=??(ls_in_arp_rsp      ), priority=50   , match=(nd_ns && ip6.dst == 
{fd00::10, ff02::1:ff00:10} && nd.target == fd00::10), action=(nd_na { eth.src 
= 50:54:00:00:00:10; ip6.src = fd00::10; nd.target = fd00::10; nd.tll = 
50:54:00:00:00:10; outport = inport; flags.loopback = 1; output; };)
+  table=??(ls_in_arp_rsp      ), priority=50   , match=(nd_ns_mcast && ip6.dst 
== {fd00::10, ff02::1:ff00:10} && nd.target == fd00::10), action=(nd_na { 
eth.src = 50:54:00:00:00:10; ip6.src = fd00::10; nd.target = fd00::10; nd.tll = 
50:54:00:00:00:10; outport = inport; flags.loopback = 1; output; };)
 ])
 
 #Set the disable_arp_nd_rsp option and verify the flow
diff --git a/tests/ovn.at b/tests/ovn.at
index a1d689e849..96a89c7d8c 100644
--- a/tests/ovn.at
+++ b/tests/ovn.at
@@ -14417,7 +14417,7 @@ test_ns_na() {
     local inport=$1 src_mac=$2 dst_mac=$3 src_ip=$4 dst_ip=$5
 
     packet=$(fmt_pkt "
-        Ether(dst='ff:ff:ff:ff:ff:ff', src='${src_mac}') /
+        Ether(dst='33:33:ff:ff:ff:ff', src='${src_mac}') /
         IPv6(src='${src_ip}', dst='ff02::1:ff00:2') /
         ICMPv6ND_NS(tgt='${dst_ip}')
     ")
diff --git a/tests/system-ovn.at b/tests/system-ovn.at
index c54b0f3a5f..980472f4e0 100644
--- a/tests/system-ovn.at
+++ b/tests/system-ovn.at
@@ -13750,3 +13750,129 @@ OVS_TRAFFIC_VSWITCHD_STOP(["/.*error receiving.*/d
 /.*terminating with signal 15.*/d"])
 AT_CLEANUP
 ])
+
+dnl This test sends IPv6 TCP packets between two lports of the same
+dnl logical switch and checks that the datapath flows don't match on
+dnl IPv6 source and destination addresses.
+OVN_FOR_EACH_NORTHD([
+AT_SETUP([ovn -- IPv6 switching - datapath flows])
+AT_KEYWORDS([IPv6])
+
+ovn_start
+OVS_TRAFFIC_VSWITCHD_START()
+ADD_BR([br-int])
+
+dnl Set external-ids in br-int needed for ovn-controller
+check ovs-vsctl \
+        -- set Open_vSwitch . external-ids:system-id=hv1 \
+        -- set Open_vSwitch . 
external-ids:ovn-remote=unix:$ovs_base/ovn-sb/ovn-sb.sock \
+        -- set Open_vSwitch . external-ids:ovn-encap-type=geneve \
+        -- set Open_vSwitch . external-ids:ovn-encap-ip=169.0.0.1 \
+        -- set bridge br-int fail-mode=secure other-config:disable-in-band=true
+
+dnl Start ovn-controller
+start_daemon ovn-controller
+
+check ovn-nbctl ls-add sw0
+
+check ovn-nbctl lsp-add sw0 vm0
+check ovn-nbctl lsp-set-addresses vm0 "f0:00:0f:01:02:03 10.0.0.3 1000::3"
+
+check ovn-nbctl lsp-add sw0 vm1
+check ovn-nbctl lsp-set-addresses vm1 "f0:00:0f:01:02:04 10.0.0.4 1000::4"
+
+check ovn-nbctl --wait=hv sync
+
+ovn-sbctl dump-flows sw0 > /tmp/c.txt
+
+ADD_NAMESPACES(vm0)
+ADD_VETH(vm0, vm0, br-int, "1000::3/64", "f0:00:0f:01:02:03", "1000::1", 
"nodad")
+
+ADD_NAMESPACES(vm1)
+ADD_VETH(vm1, vm1, br-int, "1000::4/64", "f0:00:0f:01:02:04", "1000::1", 
"nodad")
+
+dnl Checks the datapath flows and makes sure that there are no matches to
+dnl IPv6 src or dst fields.
+check_dp_flows() {
+  ipv6_src_dst_match=$1
+  dnl Dump the flows. Will be helpful while debugging.
+  ovs-appctl dpctl/dump-flows
+
+  eth_match1="eth(src=f0:00:0f:01:02:03,dst=f0:00:0f:01:02:04)"
+  eth_match2="eth(src=f0:00:0f:01:02:04,dst=f0:00:0f:01:02:03)"
+  ipv6_src_match="ipv6(src="
+  ipv6_dst_match="ipv6(dst="
+
+  AT_CHECK([ovs-appctl dpctl/dump-flows | grep "$eth_match1" -c], [0], [dnl
+2
+])
+
+  AT_CHECK([ovs-appctl dpctl/dump-flows | grep "$eth_match2" -c], [0], [dnl
+2
+])
+
+  if [[ "$ipv6_src_dst_match" == "yes" ]]; then
+    dnl Check that the dp flow for 
eth(src=f0:00:0f:01:02:03,dst=f0:00:0f:01:02:04)
+    dnl matches on IPv6 src or dst.
+    AT_CHECK([ovs-appctl dpctl/dump-flows | grep "$eth_match1" | grep -e 
"$ipv6_src_match" -e "$ipv6_dst_match" -c], [0], [dnl
+2
+])
+
+    dnl Check that the dp flow for 
eth(src=f0:00:0f:01:02:04,dst=f0:00:0f:01:02:03)
+    dnl matches on IPv6 src or dst.
+    AT_CHECK([ovs-appctl dpctl/dump-flows | grep "$eth_match2" | grep -e 
"$ipv6_src_match" -e "$ipv6_dst_match" -c], [0], [dnl
+2
+])
+  else
+    dnl Check that the dp flow for 
eth(src=f0:00:0f:01:02:03,dst=f0:00:0f:01:02:04)
+    dnl doesn't match on IPv6 src or dst.
+    AT_CHECK([ovs-appctl dpctl/dump-flows | grep "$eth_match1" | grep 
"$ipv6_src_match"], [1], [])
+    AT_CHECK([ovs-appctl dpctl/dump-flows | grep "$eth_match1" | grep 
"$ipv6_dst_match"], [1], [])
+
+    dnl Check that the dp flow for 
eth(src=f0:00:0f:01:02:04,dst=f0:00:0f:01:02:03)
+    AT_CHECK([ovs-appctl dpctl/dump-flows | grep "$eth_match2" | grep 
"$ipv6_src_match"], [1], [])
+    AT_CHECK([ovs-appctl dpctl/dump-flows | grep "$eth_match2" | grep 
"$ipv6_dst_match"], [1], [])
+  fi
+}
+
+NS_CHECK_EXEC([vm0], [ping6 -q -c 3 -i 0.3 -w 2 1000::4 | FORMAT_PING], \
+[0], [dnl
+3 packets transmitted, 3 received, 0% packet loss, time 0ms
+])
+
+# Start IPv6 TCP server on vm0.
+NETNS_DAEMONIZE([vm0], [nc -6 -l -k 1000::3 4242], [nc-vm1-1.pid])
+NS_CHECK_EXEC([vm1], [nc -6 1000::3 4242 -z], [0], [ignore], [ignore])
+
+check_dp_flows no
+
+# Now configure port security on vm0.  dp flows should now match on IPv6 
fields.
+check ovn-nbctl lsp-set-port-security vm0 "f0:00:0f:01:02:03 10.0.0.3 1000::3"
+check ovn-nbctl --wait=hv sync
+
+NS_CHECK_EXEC([vm0], [ping6 -q -c 3 -i 0.3 -w 2 1000::4 | FORMAT_PING], \
+[0], [dnl
+3 packets transmitted, 3 received, 0% packet loss, time 0ms
+])
+
+# ovs-appctl dpctl/del-flows || :
+NS_CHECK_EXEC([vm1], [nc -6 1000::3 4242 -z], [0], [ignore], [ignore])
+check_dp_flows yes
+
+OVS_APP_EXIT_AND_WAIT([ovn-controller])
+
+as ovn-sb
+OVS_APP_EXIT_AND_WAIT([ovsdb-server])
+
+as ovn-nb
+OVS_APP_EXIT_AND_WAIT([ovsdb-server])
+
+as northd
+OVS_APP_EXIT_AND_WAIT([ovn-northd])
+
+as
+OVS_TRAFFIC_VSWITCHD_STOP(["/.*error receiving.*/d
+/failed to query port patch-.*/d
+/.*terminating with signal 15.*/d"])
+AT_CLEANUP
+])
-- 
2.45.2

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