From: Nigel Cunningham <nigel@suspend2.net>
Organization: Suspend2.net
To: Pavel Machek <pavel@ucw.cz>
Subject: Re: [ 01/10] [Suspend2] kernel/power/modules.h
Date: Thu, 2 Feb 2006 20:29:28 +1000
User-Agent: KMail/1.9.1
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>, Pekka Enberg <penberg@cs.helsinki.fi>,
       linux-kernel@vger.kernel.org
References: <20060201113710.6320.68289.stgit@localhost.localdomain> <200602021922.11100.nigel@suspend2.net> <20060202101626.GD1981@elf.ucw.cz>
In-Reply-To: <20060202101626.GD1981@elf.ucw.cz>
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Hi.

On Thursday 02 February 2006 20:16, Pavel Machek wrote:
> > I'm more concerned about the security implications. I'll freely admit
> > that I haven't spent any real time looking at your code, but I'm
> > concerned that the additional functionality made available could be used
> > by viruses and the like. I'm sure you'd have to be root to do anything,
> > but how could the interfaces be misused?
>
> In vanilla kernel userland suspend has no security implications: root
> can just do what he wants in /dev/mem, anyway.

Ok.

> In fedora kernel, userland suspend can be [miss]used to snapshot an
> image, modify it, and write it back. Fortunately, this is going to
> take *long* time so people will notice. [Interface changed on DaveJ's
> request, now we have separate device, we no longer mess with
> /dev/mem]. And similar problem exists in suspend2 -- malicious
> graphical progress bar could probably modify memory image on disk.

How? It's just an ordinary process with no special permissions or access to=
=20
memory. The communication between the userspace process and the kernel is i=
n=20
the form of a netlink socket, with the only messages sent back and forth=20
being what should be displayed or what actions the user requested. Everythi=
ng=20
related to preparing the image and performing the I/O is done in the kernel=
=2E=20
There's no way I can see that a malicious userspace program could modify=20
anything but its own memory.

Regards,

Nigel
=2D-=20
See our web page for Howtos, FAQs, the Wiki and mailing list info.
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