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

[Guoheyi]

å 2019/12/4 17:29, Greg Kroah-Hartman åé:
> On Wed, Dec 04, 2019 at 05:01:06PM +0800, Guoheyi wrote:
> > å 2019/12/4 15:41, Greg Kroah-Hartman åé:
> > > 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
>
> .