linux-kernel - Re: firmware: dmi-sysfs: why is the access mode of dmi sysfs entries restricted to 0400?

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Message-ID: <20191204074133.GA3548765@kroah.com>
Date:   Wed, 4 Dec 2019 08:41:33 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Guoheyi <guoheyi@...wei.com>
Cc:     Mike Waychison <mikew@...gle.com>, linux-kernel@...r.kernel.org,
        wanghaibin 00208455 <wanghaibin.wang@...wei.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: firmware: dmi-sysfs: why is the access mode of dmi sysfs entries
 restricted to 0400?

On Wed, Dec 04, 2019 at 03:31:22PM +0800, Guoheyi wrote:
> Hi,
> 
> Why is the access mode of dmi sysfs entries restricted to 0400? Is it for
> security concern? If it is, which information do we consider as privacy?

There's lots of "interesting" information in dmi entries that you
probably do not want all processes reading, which is why they are
restricted.

> We would like to fetch CPU information from non-root application, is there
> feasible way to do that?

What specific CPU information is not currently exported in /proc/cpuinfo
that only shows up in DMI entries that you are interested in?

You can always have root change the permissions of a sysfs file if you
have a service that wants to allow non-root programs to read specific
entries.

thanks,

greg k-h