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

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Message-ID: <20170512062003.GB6803@dhcp22.suse.cz>
Date:   Fri, 12 May 2017 08:20:04 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Pavel Machek <pavel@....cz>
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 11-05-17 23:07:55, Pavel Machek wrote:
> 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?

I am pretty sure that such a user can do much larger harm than playing
with brigtness of my LCD. Anyway I went with my own rc.local hack.
-- 
Michal Hocko
SUSE Labs