Documentation: netlink: add a YAML spec for mptcp

it describes most of the current netlink interface (uAPI definitions,
doit/dumpit operations and attributes)

Link: https://github.com/multipath-tcp/mptcp_net-next/issues/340Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Link: https://lore.kernel.org/r/20231023-send-net-next-20231023-1-v2-4-16b1f701f900@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/netlink/specs/mptcp.yaml

+# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+
+name: mptcp_pm
+protocol: genetlink-legacy
+doc: Multipath TCP.
+
+c-family-name: mptcp-pm-name
+c-version-name: mptcp-pm-ver
+max-by-define: true
+kernel-policy: per-op
+
+definitions:
+  -
+    type: enum
+    name: event-type
+    enum-name: mptcp-event-type
+    name-prefix: mptcp-event-
+    entries:
+     -
+      name: unspec
+      doc: unused event
+     -
+      name: created
+      doc:
+        token, family, saddr4 | saddr6, daddr4 | daddr6, sport, dport
+        A new MPTCP connection has been created. It is the good time to
+        allocate memory and send ADD_ADDR if needed. Depending on the
+        traffic-patterns it can take a long time until the
+        MPTCP_EVENT_ESTABLISHED is sent.
+     -
+      name: established
+      doc:
+        token, family, saddr4 | saddr6, daddr4 | daddr6, sport, dport
+        A MPTCP connection is established (can start new subflows).
+     -
+      name: closed
+      doc:
+        token
+        A MPTCP connection has stopped.
+     -
+      name: announced
+      value: 6
+      doc:
+        token, rem_id, family, daddr4 | daddr6 [, dport]
+        A new address has been announced by the peer.
+     -
+      name: removed
+      doc:
+        token, rem_id
+        An address has been lost by the peer.
+     -
+      name: sub-established
+      value: 10
+      doc:
+        token, family, loc_id, rem_id, saddr4 | saddr6, daddr4 | daddr6, sport,
+        dport, backup, if_idx [, error]
+        A new subflow has been established. 'error' should not be set.
+     -
+      name: sub-closed
+      doc:
+        token, family, loc_id, rem_id, saddr4 | saddr6, daddr4 | daddr6, sport,
+        dport, backup, if_idx [, error]
+        A subflow has been closed. An error (copy of sk_err) could be set if an
+        error has been detected for this subflow.
+     -
+      name: sub-priority
+      value: 13
+      doc:
+        token, family, loc_id, rem_id, saddr4 | saddr6, daddr4 | daddr6, sport,
+        dport, backup, if_idx [, error]
+        The priority of a subflow has changed. 'error' should not be set.
+     -
+      name: listener-created
+      value: 15
+      doc:
+        family, sport, saddr4 | saddr6
+        A new PM listener is created.
+     -
+      name: listener-closed
+      doc:
+        family, sport, saddr4 | saddr6
+        A PM listener is closed.
+
+attribute-sets:
+  -
+    name: address
+    name-prefix: mptcp-pm-addr-attr-
+    attributes:
+      -
+        name: unspec
+        type: unused
+        value: 0
+      -
+        name: family
+        type: u16
+      -
+        name: id
+        type: u8
+      -
+        name: addr4
+        type: u32
+        byte-order: big-endian
+      -
+        name: addr6
+        type: binary
+        checks:
+          exact-len: 16
+      -
+        name: port
+        type: u16
+        byte-order: big-endian
+      -
+        name: flags
+        type: u32
+      -
+        name: if-idx
+        type: s32
+  -
+    name: subflow-attribute
+    name-prefix: mptcp-subflow-attr-
+    attributes:
+      -
+        name: unspec
+        type: unused
+        value: 0
+      -
+        name: token-rem
+        type: u32
+      -
+        name: token-loc
+        type: u32
+      -
+        name: relwrite-seq
+        type: u32
+      -
+        name: map-seq
+        type: u64
+      -
+        name: map-sfseq
+        type: u32
+      -
+        name: ssn-offset
+        type: u32
+      -
+        name: map-datalen
+        type: u16
+      -
+        name: flags
+        type: u32
+      -
+        name: id-rem
+        type: u8
+      -
+        name: id-loc
+        type: u8
+      -
+        name: pad
+        type: pad
+  -
+    name: endpoint
+    name-prefix: mptcp-pm-endpoint-
+    attributes:
+      -
+        name: addr
+        type: nest
+        nested-attributes: address
+  -
+    name: attr
+    name-prefix: mptcp-pm-attr-
+    attributes:
+      -
+        name: unspec
+        type: unused
+        value: 0
+      -
+        name: addr
+        type: nest
+        nested-attributes: address
+      -
+        name: rcv-add-addrs
+        type: u32
+      -
+        name: subflows
+        type: u32
+      -
+        name: token
+        type: u32
+      -
+        name: loc-id
+        type: u8
+      -
+        name: addr-remote
+        type: nest
+        nested-attributes: address
+  -
+    name: event-attr
+    enum-name: mptcp-event-attr
+    name-prefix: mptcp-attr-
+    attributes:
+      -
+        name: unspec
+        type: unused
+        value: 0
+      -
+        name: token
+        type: u32
+      -
+        name: family
+        type: u16
+      -
+        name: loc-id
+        type: u8
+      -
+        name: rem-id
+        type: u8
+      -
+        name: saddr4
+        type: u32
+        byte-order: big-endian
+      -
+        name: saddr6
+        type: binary
+        checks:
+          min-len: 16
+      -
+        name: daddr4
+        type: u32
+        byte-order: big-endian
+      -
+        name: daddr6
+        type: binary
+        checks:
+          min-len: 16
+      -
+        name: sport
+        type: u16
+        byte-order: big-endian
+      -
+        name: dport
+        type: u16
+        byte-order: big-endian
+      -
+        name: backup
+        type: u8
+      -
+        name: error
+        type: u8
+      -
+        name: flags
+        type: u16
+      -
+        name: timeout
+        type: u32
+      -
+        name: if_idx
+        type: u32
+      -
+        name: reset-reason
+        type: u32
+      -
+        name: reset-flags
+        type: u32
+      -
+        name: server-side
+        type: u8
+
+operations:
+  list:
+    -
+      name: unspec
+      doc: unused
+      value: 0
+    -
+      name: add-addr
+      doc: Add endpoint
+      attribute-set: endpoint
+      dont-validate: [ strict ]
+      flags: [ uns-admin-perm ]
+      do: &add-addr-attrs
+        request:
+          attributes:
+            - addr
+    -
+      name: del-addr
+      doc: Delete endpoint
+      attribute-set: endpoint
+      dont-validate: [ strict ]
+      flags: [ uns-admin-perm ]
+      do: *add-addr-attrs
+    -
+      name: get-addr
+      doc: Get endpoint information
+      attribute-set: endpoint
+      dont-validate: [ strict ]
+      flags: [ uns-admin-perm ]
+      do: &get-addr-attrs
+        request:
+          attributes:
+           - addr
+        reply:
+          attributes:
+           - addr
+      dump:
+        reply:
+         attributes:
+           - addr
+    -
+      name:  flush-addrs
+      doc: flush addresses
+      attribute-set: endpoint
+      dont-validate: [ strict ]
+      flags: [ uns-admin-perm ]
+      do: *add-addr-attrs
+    -
+      name: set-limits
+      doc: Set protocol limits
+      attribute-set: attr
+      dont-validate: [ strict ]
+      flags: [ uns-admin-perm ]
+      do: &mptcp-limits
+        request:
+          attributes:
+            - rcv-add-addrs
+            - subflows
+    -
+      name: get-limits
+      doc: Get protocol limits
+      attribute-set: attr
+      dont-validate: [ strict ]
+      do: &mptcp-get-limits
+        request:
+           attributes:
+            - rcv-add-addrs
+            - subflows
+        reply:
+          attributes:
+            - rcv-add-addrs
+            - subflows
+    -
+      name: set-flags
+      doc: Change endpoint flags
+      attribute-set: attr
+      dont-validate: [ strict ]
+      flags: [ uns-admin-perm ]
+      do: &mptcp-set-flags
+        request:
+          attributes:
+            - addr
+            - token
+            - addr-remote
+    -
+      name: announce
+      doc: announce new sf
+      attribute-set: attr
+      dont-validate: [ strict ]
+      flags: [ uns-admin-perm ]
+      do: &announce-add
+        request:
+          attributes:
+            - addr
+            - token
+    -
+      name: remove
+      doc: announce removal
+      attribute-set: attr
+      dont-validate: [ strict ]
+      flags: [ uns-admin-perm ]
+      do:
+        request:
+         attributes:
+           - token
+           - loc-id
+    -
+      name: subflow-create
+      doc: todo
+      attribute-set: attr
+      dont-validate: [ strict ]
+      flags: [ uns-admin-perm ]
+      do: &sf-create
+        request:
+          attributes:
+            - addr
+            - token
+            - addr-remote
+    -
+      name: subflow-destroy
+      doc: todo
+      attribute-set: attr
+      dont-validate: [ strict ]
+      flags: [ uns-admin-perm ]
+      do: *sf-create

MAINTAINERS

@@ -14960,6 +14960,7 @@ W:	https://github.com/multipath-tcp/mptcp_net-next/wiki
 B:	https://github.com/multipath-tcp/mptcp_net-next/issues
 T:	git https://github.com/multipath-tcp/mptcp_net-next.git export-net
 T:	git https://github.com/multipath-tcp/mptcp_net-next.git export
+F:	Documentation/netlink/specs/mptcp.yaml
 F:	Documentation/networking/mptcp-sysctl.rst
 F:	include/net/mptcp.h
 F:	include/trace/events/mptcp.h