netdev-vport: Deprecate STT tunnel port type.

STT tunnel implementation was rejected in the upstream Linux kernel long time ago and will probably never be there. So, the only implementation for Linux is in the OOT kernel module shipped with OVS 2.17. It is deprecated and will reach end of life in Feb 2025. Deprecate the port type now, so it can be removed once 2.17 is EoL. There is another implementation for this tunnel type in the Windows datapath. However, the protocol itself is considered harmful as it may confuse stateful network hardware by pretending to be TCP (hence the reason it was rejected in the Linux kernel). So, it is better if we deprecate this implementation and stop supporting it as well. The standard draft for the protocol itself is also expired and archived with the latest update made in 2016: https://datatracker.ietf.org/doc/draft-davie-stt/ Signed-off-by: Ilya Maximets <[email protected]>
igsilya · Dec 4, 2024 · e019bf9 · e019bf9
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Showing 7 changed files with 34 additions and 19 deletions.
diff --git a/Documentation/faq/releases.rst b/Documentation/faq/releases.rst
@@ -142,7 +142,7 @@ Q: Are all features available with all datapaths?
     Conntrack NAT6                  4.6            2.6          2.8      3.0
     Conntrack Helper Persist.       YES            YES          3.3      NO
     Tunnel - LISP (deprecated)      NO             2.11         NO       NO
-    Tunnel - STT                    NO             2.4          NO       YES
+    Tunnel - STT  (deprecated)      NO             2.4          NO       YES
     Tunnel - GRE                    3.11           1.0          2.4      YES
     Tunnel - VXLAN                  3.12           1.10         2.4      YES
     Tunnel - Geneve                 3.18           2.4          2.4      YES

diff --git a/Documentation/intro/install/windows.rst b/Documentation/intro/install/windows.rst
@@ -703,7 +703,8 @@ Add tunnels
 
 #. IPv4 tunnel, e.g.:
 
-   The Windows Open vSwitch implementation support VXLAN and STT tunnels.
+   The Windows Open vSwitch implementation support VXLAN and STT tunnels
+   (STT tunnel ports are deprecated).
    To add tunnels. For example, first add the tunnel port between
    172.168.201.101 <->172.168.201.102:
 

diff --git a/NEWS b/NEWS
@@ -26,8 +26,8 @@ Post-v3.4.0
    - DPDK:
      * OVS validated with DPDK 23.11.2.
    - Tunnels:
-     * LISP tunnel port type is deprecated and will be removed in the next
-       release.
+     * LISP and STT tunnel port types are deprecated and will be removed in
+       the next release.
 
 
 v3.4.0 - 15 Aug 2024

diff --git a/include/linux/openvswitch.h b/include/linux/openvswitch.h
@@ -248,7 +248,7 @@ enum ovs_vport_type {
 	OVS_VPORT_TYPE_VXLAN,	 /* VXLAN tunnel. */
 	OVS_VPORT_TYPE_GENEVE,	 /* Geneve tunnel. */
 	OVS_VPORT_TYPE_LISP = 105,  /* LISP tunnel (deprecated). */
-	OVS_VPORT_TYPE_STT = 106, /* STT tunnel */
+	OVS_VPORT_TYPE_STT = 106, /* STT tunnel (deprecated). */
 	OVS_VPORT_TYPE_ERSPAN = 107, /* ERSPAN tunnel. */
 	OVS_VPORT_TYPE_IP6ERSPAN = 108, /* ERSPAN tunnel. */
 	OVS_VPORT_TYPE_IP6GRE = 109,

diff --git a/lib/netdev-vport.c b/lib/netdev-vport.c
@@ -229,6 +229,7 @@ netdev_vport_construct(struct netdev *netdev_)
         VLOG_WARN("%s: 'lisp' port type is deprecated.", name);
     } else if (!strcmp(type, "stt")) {
         tnl_cfg->dst_port = port ? htons(port) : htons(STT_DST_PORT);
+        VLOG_WARN("%s: 'stt' port type is deprecated.", name);
     } else if (!strcmp(type, "gtpu")) {
         tnl_cfg->dst_port = port ? htons(port) : htons(GTPU_DST_PORT);
     } else if (!strcmp(type, "bareudp")) {

diff --git a/tests/ofproto-dpif.at b/tests/ofproto-dpif.at
@@ -8658,7 +8658,7 @@ dnl Remove the flow which contains sample action.
 AT_CHECK([ovs-ofctl del-flows br0 in_port=3], [0], [ignore])
 AT_CHECK([ovs-vsctl destroy Flow_Sample_Collector_Set 1], [0], [ignore])
 
-OVS_VSWITCHD_STOP
+OVS_VSWITCHD_STOP(["/'stt' port type is deprecated/d"])
 AT_CLEANUP
 
 AT_SETUP([ofproto-dpif - Flow IPFIX sanity check - from field])

diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
@@ -2844,20 +2844,33 @@
 
           <dt><code>stt</code></dt>
           <dd>
-            The Stateless TCP Tunnel (STT) is particularly useful when tunnel
-            endpoints are in end-systems, as it utilizes the capabilities of
-            standard network interface cards to improve performance.  STT utilizes
-            a TCP-like header inside the IP header. It is stateless, i.e., there is
-            no TCP connection state of any kind associated with the tunnel.  The
-            TCP-like header is used to leverage the capabilities of existing
-            network interface cards, but should not be interpreted as implying
-            any sort of connection state between endpoints.
-            Since the STT protocol does not engage in the usual TCP 3-way handshake,
-            so it will have difficulty traversing stateful firewalls.
-            The protocol is documented at
-            https://tools.ietf.org/html/draft-davie-stt
+            <p>
+              This port type is deprecated.
+            </p>
+
+            <p>
+              The Stateless TCP Tunnel (STT) is particularly useful when tunnel
+              endpoints are in end-systems, as it utilizes the capabilities of
+              standard network interface cards to improve performance.
+              STT utilizes a TCP-like header inside the IP header.  It is
+              stateless, i.e., there is no TCP connection state of any kind
+              associated with the tunnel.  The TCP-like header is used to
+              leverage the capabilities of existing network interface cards,
+              but should not be interpreted as implying any sort of connection
+              state between endpoints.
+            </p>
+
+            <p>
+              Since the STT protocol does not engage in the usual TCP 3-way
+              handshake, so it will have difficulty traversing stateful
+              firewalls.
+            </p>
 
-            All traffic uses a default destination port of 7471.
+            <p>
+              The protocol is documented at
+              <code>https://tools.ietf.org/html/draft-davie-stt</code>.
+              All traffic uses a default destination port of 7471.
+            </p>
           </dd>
 
           <dt><code>patch</code></dt>