Re: [RFC net-next 4/4] ynl: add a sample user for ethtool

[Ido Schimmel <idosch@idosch.org>]

On Wed, Aug 10, 2022 at 07:23:04PM -0700, Jakub Kicinski wrote:
> @@ -0,0 +1,115 @@
> +# SPDX-License-Identifier: BSD-3-Clause
> +
> +name: ethtool
> +
> +description: |
> +  Ethernet device configuration interface.
> +
> +attr-cnt-suffix: CNT
> +
> +attribute-spaces:
> +  -
> +    name: header
> +    name-prefix: ETHTOOL_A_HEADER_
> +    attributes:
> +      -
> +        name: dev_index
> +        val: 1
> +        type: u32
> +      -
> +        name: dev_name
> +        type: nul-string
> +        len: ALTIFNAMSIZ - 1
> +      -
> +        name: flags
> +        type: u32
> +  -
> +    name: channels
> +    name-prefix: ETHTOOL_A_CHANNELS_
> +    attributes:
> +      -
> +        name: header
> +        val: 1
> +        type: nest
> +        nested-attributes: header
> +      -
> +        name: rx_max
> +        type: u32
> +      -
> +        name: tx_max
> +        type: u32
> +      -
> +        name: other_max
> +        type: u32
> +      -
> +        name: combined_max
> +        type: u32
> +      -
> +        name: rx_count
> +        type: u32
> +      -
> +        name: tx_count
> +        type: u32
> +      -
> +        name: other_count
> +        type: u32
> +      -
> +        name: combined_count
> +        type: u32

Another interesting use case for the schema can be automatic generation
of syzkaller descriptions. These are the corresponding descriptions for
syzkaller:

https://github.com/google/syzkaller/blob/master/sys/linux/socket_netlink_generic_ethtool.txt#L125

Last I checked, these descriptions had to be written by hand, which is
why they are generally out of date, leading to sub-optimal fuzzing. If
schemas are sent along with the kernel code and syzkaller/syzbot
automatically derives descriptions from them, then we should be able to
get meaningful fuzzing as soon as a feature lands in net-next.

> +
> +headers:
> +  user: linux/if.h
> +  uapi: linux/ethtool_netlink.h
> +
> +operations:
> +  name-prefix: ETHTOOL_MSG_
> +  async-prefix: ETHTOOL_MSG_
> +  list:
> +    -
> +      name: channels_get
> +      val: 17
> +      description: Get current and max supported number of channels.
> +      attribute-space: channels
> +      do:
> +        request:
> +          attributes:
> +            - header
> +        reply: &channel_reply
> +          attributes:
> +            - header
> +            - rx_max
> +            - tx_max
> +            - other_max
> +            - combined_max
> +            - rx_count
> +            - tx_count
> +            - other_count
> +            - combined_count
> +      dump:
> +        reply: *channel_reply
> +
> +    -
> +      name: channels_ntf
> +      description: Notification for device changing its number of channels.
> +      notify: channels_get
> +      mcgrp: monitor
> +
> +    -
> +      name: channels_set
> +      description: Set number of channels.
> +      attribute-space: channels
> +      do:
> +        request:
> +          attributes:
> +            - header
> +            - rx_count
> +            - tx_count
> +            - other_count
> +            - combined_count
> +
> +mcast-groups:
> +  name-prefix: ETHTOOL_MCGRP_
> +  name-suffix: _NAME
> +  list:
> +    -
> +      name: monitor