linux/Documentation/netlink/genetlink-c.yaml

# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
%YAML 1.2
---
$id: http://kernel.org/schemas/netlink/genetlink-c.yaml#
$schema: https://json-schema.org/draft-07/schema

# Common defines
$defs:
  uint:
    type: integer
    minimum: 0
  len-or-define:
    type: [ string, integer ]
    pattern: ^[0-9A-Za-z_-]+( - 1)?$
    minimum: 0
  len-or-limit:
    # literal int or limit based on fixed-width type e.g. u8-min, u16-max, etc.
    type: [ string, integer ]
    pattern: ^[su](8|16|32|64)-(min|max)$
    minimum: 0

# Schema for specs
title: Protocol
description: Specification of a genetlink protocol
type: object
required: [ name, doc, attribute-sets, operations ]
additionalProperties: False
properties:
  name:
    description: Name of the genetlink family.
    type: string
  doc:
    type: string
  protocol:
    description: Schema compatibility level. Default is "genetlink".
    enum: [ genetlink, genetlink-c ]
  uapi-header:
    description: Path to the uAPI header, default is linux/${family-name}.h
    type: string
  # Start genetlink-c
  c-family-name:
    description: Name of the define for the family name.
    type: string
  c-version-name:
    description: Name of the define for the version of the family.
    type: string
  max-by-define:
    description: Makes the number of attributes and commands be specified by a define, not an enum value.
    type: boolean
  cmd-max-name:
    description: Name of the define for the last operation in the list.
    type: string
  cmd-cnt-name:
    description: The explicit name for constant holding the count of operations (last operation + 1).
    type: string
  # End genetlink-c

  definitions:
    description: List of type and constant definitions (enums, flags, defines).
    type: array
    items:
      type: object
      required: [ type, name ]
      additionalProperties: False
      properties:
        name:
          type: string
        header:
          description: For C-compatible languages, header which already defines this value.
          type: string
        type:
          enum: [ const, enum, flags ]
        doc:
          type: string
        # For const
        value:
          description: For const - the value.
          type: [ string, integer ]
        # For enum and flags
        value-start:
          description: For enum or flags the literal initializer for the first value.
          type: [ string, integer ]
        entries:
          description: For enum or flags array of values.
          type: array
          items:
            oneOf:
              - type: string
              - type: object
                required: [ name ]
                additionalProperties: False
                properties:
                  name:
                    type: string
                  value:
                    type: integer
                  doc:
                    type: string
        render-max:
          description: Render the max members for this enum.
          type: boolean
        # Start genetlink-c
        enum-name:
          description: Name for enum, if empty no name will be used.
          type: [ string, "null" ]
        name-prefix:
          description: For enum the prefix of the values, optional.
          type: string
        # End genetlink-c

  attribute-sets:
    description: Definition of attribute spaces for this family.
    type: array
    items:
      description: Definition of a single attribute space.
      type: object
      required: [ name, attributes ]
      additionalProperties: False
      properties:
        name:
          description: |
            Name used when referring to this space in other definitions, not used outside of the spec.            
          type: string
        name-prefix:
          description: |
            Prefix for the C enum name of the attributes. Default family[name]-set[name]-a-            
          type: string
        enum-name:
          description: |
            Name for the enum type of the attribute, if empty no name will be used.            
          type: [ string, "null" ]
        doc:
          description: Documentation of the space.
          type: string
        subset-of:
          description: |
            Name of another space which this is a logical part of. Sub-spaces can be used to define
            a limited group of attributes which are used in a nest.            
          type: string
        # Start genetlink-c
        attr-cnt-name:
          description: The explicit name for constant holding the count of attributes (last attr + 1).
          type: string
        attr-max-name:
          description: The explicit name for last member of attribute enum.
          type: string
        # End genetlink-c
        attributes:
          description: List of attributes in the space.
          type: array
          items:
            type: object
            required: [ name ]
            additionalProperties: False
            properties:
              name:
                type: string
              type: &attr-type
                enum: [ unused, pad, flag, binary,
                        uint, sint, u8, u16, u32, u64, s32, s64,
                        string, nest, indexed-array, nest-type-value ]
              doc:
                description: Documentation of the attribute.
                type: string
              value:
                description: Value for the enum item representing this attribute in the uAPI.
                $ref: '#/$defs/uint'
              type-value:
                description: Name of the value extracted from the type of a nest-type-value attribute.
                type: array
                items:
                  type: string
              byte-order:
                enum: [ little-endian, big-endian ]
              multi-attr:
                type: boolean
              nested-attributes:
                description: Name of the space (sub-space) used inside the attribute.
                type: string
              enum:
                description: Name of the enum type used for the attribute.
                type: string
              enum-as-flags:
                description: |
                  Treat the enum as flags. In most cases enum is either used as flags or as values.
                  Sometimes, however, both forms are necessary, in which case header contains the enum
                  form while specific attributes may request to convert the values into a bitfield.                  
                type: boolean
              checks:
                description: Kernel input validation.
                type: object
                additionalProperties: False
                properties:
                  flags-mask:
                    description: Name of the flags constant on which to base mask (unsigned scalar types only).
                    type: string
                  min:
                    description: Min value for an integer attribute.
                    $ref: '#/$defs/len-or-limit'
                  max:
                    description: Max value for an integer attribute.
                    $ref: '#/$defs/len-or-limit'
                  min-len:
                    description: Min length for a binary attribute.
                    $ref: '#/$defs/len-or-define'
                  max-len:
                    description: Max length for a string or a binary attribute.
                    $ref: '#/$defs/len-or-define'
                  exact-len:
                    description: Exact length for a string or a binary attribute.
                    $ref: '#/$defs/len-or-define'
                  unterminated-ok:
                    description: |
                      For string attributes, do not check whether attribute
                      contains the terminating null character.                      
                    type: boolean
              sub-type: *attr-type
              display-hint: &display-hint
                description: |
                  Optional format indicator that is intended only for choosing
                  the right formatting mechanism when displaying values of this
                  type.                  
                enum: [ hex, mac, fddi, ipv4, ipv6, uuid ]
              # Start genetlink-c
              name-prefix:
                type: string
              # End genetlink-c

      # Make sure name-prefix does not appear in subsets (subsets inherit naming)
      dependencies:
        name-prefix:
          not:
            required: [ subset-of ]
        subset-of:
          not:
            required: [ name-prefix ]

      # type property is only required if not in subset definition
      if:
        properties:
          subset-of:
            not:
              type: string
      then:
        properties:
          attributes:
            items:
              required: [ type ]

  operations:
    description: Operations supported by the protocol.
    type: object
    required: [ list ]
    additionalProperties: False
    properties:
      enum-model:
        description: |
          The model of assigning values to the operations.
          "unified" is the recommended model where all message types belong
          to a single enum.
          "directional" has the messages sent to the kernel and from the kernel
          enumerated separately.          
        enum: [ unified ]
      name-prefix:
        description: |
          Prefix for the C enum name of the command. The name is formed by concatenating
          the prefix with the upper case name of the command, with dashes replaced by underscores.          
        type: string
      enum-name:
        description: |
          Name for the enum type with commands, if empty no name will be used.          
        type: [ string, "null" ]
      async-prefix:
        description: Same as name-prefix but used to render notifications and events to separate enum.
        type: string
      async-enum:
        description: |
          Name for the enum type with commands, if empty no name will be used.          
        type: [ string, "null" ]
      list:
        description: List of commands
        type: array
        items:
          type: object
          additionalProperties: False
          required: [ name, doc ]
          properties:
            name:
              description: Name of the operation, also defining its C enum value in uAPI.
              type: string
            doc:
              description: Documentation for the command.
              type: string
            value:
              description: Value for the enum in the uAPI.
              $ref: '#/$defs/uint'
            attribute-set:
              description: |
                Attribute space from which attributes directly in the requests and replies
                to this command are defined.                
              type: string
            flags: &cmd_flags
              description: Command flags.
              type: array
              items:
                enum: [ admin-perm ]
            dont-validate:
              description: Kernel attribute validation flags.
              type: array
              items:
                enum: [ strict, dump, dump-strict ]
            config-cond:
              description: |
                Name of the kernel config option gating the presence of
                the operation, without the 'CONFIG_' prefix.                
              type: string
            do: &subop-type
              description: Main command handler.
              type: object
              additionalProperties: False
              properties:
                request: &subop-attr-list
                  description: Definition of the request message for a given command.
                  type: object
                  additionalProperties: False
                  properties:
                    attributes:
                      description: |
                        Names of attributes from the attribute-set (not full attribute
                        definitions, just names).                        
                      type: array
                      items:
                        type: string
                reply: *subop-attr-list
                pre:
                  description: Hook for a function to run before the main callback (pre_doit or start).
                  type: string
                post:
                  description: Hook for a function to run after the main callback (post_doit or done).
                  type: string
            dump: *subop-type
            notify:
              description: Name of the command sharing the reply type with this notification.
              type: string
            event:
              type: object
              additionalProperties: False
              properties:
                attributes:
                  description: Explicit list of the attributes for the notification.
                  type: array
                  items:
                    type: string
            mcgrp:
              description: Name of the multicast group generating given notification.
              type: string
  mcast-groups:
    description: List of multicast groups.
    type: object
    required: [ list ]
    additionalProperties: False
    properties:
      list:
        description: List of groups.
        type: array
        items:
          type: object
          required: [ name ]
          additionalProperties: False
          properties:
            name:
              description: |
                The name for the group, used to form the define and the value of the define.                
              type: string
            # Start genetlink-c
            c-define-name:
              description: Override for the name of the define in C uAPI.
              type: string
            # End genetlink-c
            flags: *cmd_flags

  kernel-family:
    description: Additional global attributes used for kernel C code generation.
    type: object
    additionalProperties: False
    properties:
      headers:
        description: |
          List of extra headers which should be included in the source
          of the generated code.          
        type: array
        items:
          type: string
      sock-priv:
        description: |
          Literal name of the type which is used within the kernel
          to store the socket state. The type / structure is internal
          to the kernel, and is not defined in the spec.          
        type: string