linux-kernel - Re: [PATCH] dmi: export dmi data through debugfs

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Message-Id: <201009300932.34827.bjorn.helgaas@hp.com>
Date:	Thu, 30 Sep 2010 09:32:33 -0600
From:	Bjorn Helgaas <bjorn.helgaas@...com>
To:	Jean Delvare <khali@...ux-fr.org>
Cc:	Olof Johansson <olof@...om.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH] dmi: export dmi data through debugfs

On Wednesday, September 29, 2010 09:11:18 am Jean Delvare wrote:
> On Wed, 29 Sep 2010 09:53:30 -0500, Olof Johansson wrote:
> > On Wed, Sep 29, 2010 at 09:34:03AM +0200, Jean Delvare wrote:
> > > Hi Olaf,
> > > 
> > > On Tue, 28 Sep 2010 16:12:46 -0500, Olof Johansson wrote:
> > > > I've found this quite useful since it allows dmidecode to run without
> > > > root privileges using --from-dump to read this file instead
> > > 
> > > This is a bad idea. We do NOT want every user to have access to all the
> > > DMI information. There is sensitive information in there (serial
> > > numbers and UUIDs, and possibly even more sensitive data in
> > > OEM-specific records.)

If DMI has sensitive information, then I agree, we shouldn't expose
the whole table to non-root users.  I don't know the original motivation
for allowing non-root access for dmidecode -- maybe it could be addressed
by making dmidecode smart enough to look at /sys/class/dmi/id/* when
running as a non-root user?

> > It's
> > still better than having a userspace tool dig around /dev/mem for the
> > information.

I don't like /dev/mem either.  If someone's making an effort to remove
/dev/mem, this might be one piece.  But I don't know whether that's
feasible.

> Now if you really insist on exposing the whole DMI table through sysfs,
> I can't prevent you from doing that. After all, ACPI already exposes
> its tables under /sys/firmware/acpi/tables (mode 0400). But then you'd
> rather expose the DMI entry point and tables
> under /sys/firmware/dmi/tables for consistency, rather than using
> debugfs.

If you do pursue this on the grounds of migrating away from /dev/mem,
I like the idea of making it similar to what ACPI does.

Bjorn
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