linux-kernel - Re: DRM security flaws and security levels.

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Message-ID: <CANq1E4Rr5XDR3+WLRHSw6aYw6uDq90JJZOhmUKDJj=kFGcvJ8g@mail.gmail.com>
Date:	Fri, 11 Apr 2014 22:31:01 +0200
From:	David Herrmann <dh.herrmann@...il.com>
To:	Thomas Hellstrom <thellstrom@...are.com>
Cc:	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: DRM security flaws and security levels.

Hi

On Fri, Apr 11, 2014 at 2:42 PM, Thomas Hellstrom <thellstrom@...are.com> wrote:
> as was discussed a while ago, there are some serious security flaws with
> the current drm master model, that allows a
> user that had previous access or current access to an X server terminal
> to access the GPU memory of the active X server, without being
> authenticated to the X server and thereby also access other user's
> secret information

1a) and 1b) are moot if you disallow primary-node access but require
clients to use render-nodes with dma-buf. There're no gem-names on
render-nodes so no way to access other buffers (assuming the GPU does
command-stream checking and/or VM).

2) There is no DRM-generic data other than buffers that is global. So
imho this is a driver-specific issue.

So I cannot see why this is a DRM issue. The only leaks I see are
legacy interfaces and driver-specific interfaces. The first can be
disabled via chmod() for clients, and the second is something driver
authors should fix.

Thanks
David
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