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Subject: Re: firmware: dmi-sysfs: why is the access mode of dmi sysfs entries
 restricted to 0400?
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC:     Mike Waychison <mikew@google.com>, <linux-kernel@vger.kernel.org>,
        wanghaibin 00208455 <wanghaibin.wang@huawei.com>,
        Thomas Gleixner <tglx@linutronix.de>
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 <20191204074133.GA3548765@kroah.com>
 <dac22bed-f138-471e-c19a-e31c5c910d48@huawei.com>
 <20191204092942.GA3557583@kroah.com>
From:   Guoheyi <guoheyi@huawei.com>
Message-ID: <b75e2aac-e27c-8d26-36c7-6fb69b769bbd@huawei.com>
Date:   Fri, 6 Dec 2019 10:04:31 +0800
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在 2019/12/4 17:29, Greg Kroah-Hartman 写道:
> On Wed, Dec 04, 2019 at 05:01:06PM +0800, Guoheyi wrote:
>> 在 2019/12/4 15:41, Greg Kroah-Hartman 写道:
>>> 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?
>> We'd like to get processor manufacturer, speed and version, and pass the
>> information to qemu virtual machine, for users of VM might be happy to see
>> this instead of "unknown xxx", while qemu may run as non-root.
> Careful about this as if you move that virtual machine around, those
> values will change and if userspace was depending on them being static
> (set up at program start time), then you might have problems.
>
> good luck!

The information will be used as VM DMI/SMBIOS as well, so it will be 
read only once during VM boot. I guess we will be OK :)

Thanks a lot.

Heyi

>
> greg k-h
>
> .