Re: [PATCH 06/12] platform/x86: dell-wmi-smbios: Add a sysfs interface for SMBIOS tokens

From	Andy Shevchenko <andy.shevchenko@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 06/12] platform/x86: dell-wmi-smbios: Add a sysfs interface for SMBIOS tokens
Date	2017-09-25 19:10 +0200
Message-ID	<utF3j-So-3@gated-at.bofh.it> (permalink)
References	<usabf-1IE-3@gated-at.bofh.it> <usabg-1IE-11@gated-at.bofh.it> <utEqB-mA-3@gated-at.bofh.it>
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On Mon, Sep 25, 2017 at 7:23 PM, Pali Rohár <pali.rohar@gmail.com> wrote:
> On Thursday 21 September 2017 08:57:11 Mario Limonciello wrote:
>> Currently userspace tools can access system tokens via the dcdbas
>> kernel module and a SMI call that will cause the platform to execute
>> SMM code.
>>
>> With a goal in mind of deprecating the dcdbas kernel module a different
>> method for accessing these tokens from userspace needs to be created.
>>
>> This is intentionally marked to only be readable as root as it can
>> contain sensitive information about the platform's configuration.
>
> Darren, Andy, any comments? I'm not quite sure if such API is suitable
> for long term in kernel.

I would try to avoid sysfs interfaces for some particular devices.
Besides we are creating a character device. Would it be suitable there?

> Basically tokens are list of tuples <id, location, value> with
> possibility to active them, right?
>
> Does not kernel have some better API for it?

I think the best what kernel may provide is a CSV-like format with or
without title line and different delimiter (TAB/space/etc).

>
> Also, keep in mind security aspect of tokens. They represent e.g. boot
> order priority or enable/disable some machine peripheral.

For IOCTLs we may use capabilities.
In sysfs case we may zero output based on capabilities or some other factors.

-- 
With Best Regards,
Andy Shevchenko

Thread

[PATCH 06/12] platform/x86: dell-wmi-smbios: Add a sysfs interface for SMBIOS tokens Mario Limonciello <mario.limonciello@dell.com> - 2017-09-21 16:00 +0200
  Re: [PATCH 06/12] platform/x86: dell-wmi-smbios: Add a sysfs  interface for SMBIOS tokens Pali Rohár <pali.rohar@gmail.com> - 2017-09-25 18:30 +0200
    Re: [PATCH 06/12] platform/x86: dell-wmi-smbios: Add a sysfs  interface for SMBIOS tokens Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-09-25 19:10 +0200
      RE: [PATCH 06/12] platform/x86: dell-wmi-smbios: Add a sysfs  interface for SMBIOS tokens <Mario.Limonciello@dell.com> - 2017-09-25 19:40 +0200

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