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From: James.Bottomley@suse.de (James Bottomley)
To: linux-arm-kernel@lists.infradead.org
Subject: [Security] [PATCH 00/20] world-writable files in sysfs and debugfs
Date: Tue, 15 Mar 2011 12:32:31 -0400	[thread overview]
Message-ID: <1300206751.11313.3.camel@mulgrave.site> (raw)
In-Reply-To: <20110315160804.GA3380@albatros>

On Tue, 2011-03-15 at 19:08 +0300, Vasiliy Kulikov wrote:
> On Tue, Mar 15, 2011 at 07:50 -0400, James Bottomley wrote:
> >      1. Did anyone actually check for capabilities before assuming world
> >         writeable files were wrong?
> 
> I didn't check all these files as I haven't got these hardware :-)

You don't need the hardware to check ... the question becomes is a
capabilities test sitting in the implementation or not.

>   But
> as I can "chmod a+w" all sysfs files on my machine and they all become
> sensible to nonroot writes, I suppose there is nothing preventing
> nonroot users from writing to these buggy sysfs files.  As you can see,
> there are no capable() checks in these drivers in open() or write().
> 
> >      2. Even if there aren't any capabilities checks in the implementing
> >         routines, should there be (are we going the separated
> >         capabilities route vs the monolithic root route)?
> 
> IMO, In any case old good DAC security model must not be obsoleted just
> because someone thinks that MAC or anything else is more convenient for
> him.  If sysfs is implemented via filesystem then it must support POSIX
> permissions semantic.  MAC is very good in _some_ cases, but not instead
> of DAC.

Um, I'm not sure that's even an issue.  capabilities have CAP_ADMIN
which is precisely the same check as owner == root.  We use this a lot
because ioctls ignore the standard unix DAC model.

James

      reply	other threads:[~2011-03-15 16:32 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-04 12:22 [PATCH 00/20] world-writable files in sysfs and debugfs Vasiliy Kulikov
2011-02-04 12:23 ` [PATCH 01/20] mach-omap2: mux: world-writable debugfs files Vasiliy Kulikov
2011-02-04 20:09   ` Tony Lindgren
2011-02-04 12:23 ` [PATCH 02/20] mach-omap2: pm: world-writable debugfs timer files Vasiliy Kulikov
2011-02-04 20:10   ` Tony Lindgren
2011-02-04 22:53   ` Kevin Hilman
2011-02-04 12:23 ` [PATCH 03/20] mach-omap2: smartreflex: world-writable debugfs voltage files Vasiliy Kulikov
2011-02-04 20:10   ` Tony Lindgren
2011-02-04 22:54   ` Kevin Hilman
2011-02-07  5:33     ` Menon, Nishanth
2011-02-04 12:23 ` [PATCH 04/20] mach-ux500: mbox-db5500: world-writable sysfs fifo file Vasiliy Kulikov
2011-02-04 12:23 ` [PATCH 08/20] mfd: ab3100: world-writable debugfs *_priv files Vasiliy Kulikov
2011-02-04 12:23 ` [PATCH 09/20] mfd: ab3500: world-writable debugfs register-* files Vasiliy Kulikov
2011-02-04 12:23 ` [PATCH 10/20] mfd: ab8500: " Vasiliy Kulikov
2011-02-04 13:11 ` [rtc-linux] [PATCH 00/20] world-writable files in sysfs and debugfs Linus Walleij
2011-03-12 20:23 ` Vasiliy Kulikov
2011-03-14 22:18   ` [Security] " Andrew Morton
2011-03-15  2:26   ` James Bottomley
2011-03-15  3:09     ` [Security] " Greg KH
2011-03-15 11:50       ` James Bottomley
2011-03-15 14:18         ` Greg KH
2011-03-15 14:25           ` James Bottomley
2011-03-15 16:08         ` Vasiliy Kulikov
2011-03-15 16:32           ` James Bottomley [this message]

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