netlink: specs: rt_link: decode ip6tnl, vti and vti6 link attrs

Some of our tests load vti and ip6tnl so not being able to decode
the link attrs gets in the way of using Python YNL for testing.

Decode link attributes for ip6tnl, vti and vti6.

ip6tnl uses IFLA_IPTUN_FLAGS as u32, while ipv4 and sit expect
a u16 attribute, so we have a (first?) subset type override...

Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250107022820.2087101-4-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/netlink/specs/rt_link.yaml

@@ -1825,6 +1825,48 @@ attribute-sets:
       -
         name: erspan-hwid
         type: u16
+  -
+    name: linkinfo-vti-attrs
+    name-prefix: ifla-vti-
+    attributes:
+      -
+        name: link
+        type: u32
+      -
+        name: ikey
+        type: u32
+      -
+        name: okey
+        type: u32
+      -
+        name: local
+        type: binary
+        display-hint: ipv4
+      -
+        name: remote
+        type: binary
+        display-hint: ipv4
+      -
+        name: fwmark
+        type: u32
+  -
+    name: linkinfo-vti6-attrs
+    subset-of: linkinfo-vti-attrs
+    attributes:
+      -
+        name: link
+      -
+        name: ikey
+      -
+        name: okey
+      -
+        name: local
+        display-hint: ipv6
+      -
+        name: remote
+        display-hint: ipv6
+      -
+        name: fwmark
   -
     name: linkinfo-geneve-attrs
     name-prefix: ifla-geneve-
@@ -1941,6 +1983,42 @@ attribute-sets:
       -
         name: fwmark
         type: u32
+  -
+    name: linkinfo-ip6tnl-attrs
+    subset-of: linkinfo-iptun-attrs
+    attributes:
+      -
+        name: link
+      -
+        name: local
+        display-hint: ipv6
+      -
+        name: remote
+        display-hint: ipv6
+      -
+        name: ttl
+      -
+        name: encap-limit
+      -
+        name: flowinfo
+      -
+        name: flags
+        # ip6tnl unlike ipip and sit has 32b flags
+        type: u32
+      -
+        name: proto
+      -
+        name: encap-type
+      -
+        name: encap-flags
+      -
+        name: encap-sport
+      -
+        name: encap-dport
+      -
+        name: collect-metadata
+      -
+        name: fwmark
   -
     name: linkinfo-tun-attrs
     name-prefix: ifla-tun-
@@ -2201,6 +2279,9 @@ sub-messages:
       -
         value: ipip
         attribute-set: linkinfo-iptun-attrs
+      -
+        value: ip6tnl
+        attribute-set: linkinfo-ip6tnl-attrs
       -
         value: sit
         attribute-set: linkinfo-iptun-attrs
@@ -2213,6 +2294,12 @@ sub-messages:
       -
         value: vrf
         attribute-set: linkinfo-vrf-attrs
+      -
+        value: vti
+        attribute-set: linkinfo-vti-attrs
+      -
+        value: vti6
+        attribute-set: linkinfo-vti6-attrs
       -
         value: netkit
         attribute-set: linkinfo-netkit-attrs