linux-kernel - Re: setting brightness as privileged operation?

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Message-ID: <20170511210755.GA1360@xo-6d-61-c0.localdomain>
Date:   Thu, 11 May 2017 23:07:55 +0200
From:   Pavel Machek <pavel@....cz>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Jingoo Han <jingoohan1@...il.com>,
        Lee Jones <lee.jones@...aro.org>, linux-fbdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: setting brightness as privileged operation?

On Thu 2017-01-05 10:23:07, Michal Hocko wrote:
> Hi,
> I have just learned that my Xfce Power Manager cannot manipulate
> brightness because I do not have policykit installed on my computer.
> There is a reason for that (yeah it depends on systemd which I prefer
> not have).
> 
> While this is clearly a problem of the Xfce applet I am wondering why
> setting the brightness has to be a privileged operation at all. Is there
> any strong reason for it or just a general policy that we do not give
> world writable files into sysfs?

Well, if you have another user logged in using ssh, and changing _your_
brightness, that will be somehow annoying, right?

That's the reason why global settings should be root-only...

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html