linux-kernel - Re: [PATCH] power: disable hibernation if module loading is disabled

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Message-Id: <201103042148.39944.rjw@sisk.pl>
Date:	Fri, 4 Mar 2011 21:48:39 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Kees Cook <kees.cook@...onical.com>
Cc:	Vasiliy Kulikov <segoon@...nwall.com>,
	linux-kernel@...r.kernel.org, security@...nel.org,
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	linux-pm@...ts.linux-foundation.org
Subject: Re: [PATCH] power: disable hibernation if module loading is disabled

On Friday, March 04, 2011, Kees Cook wrote:
> On Fri, Mar 04, 2011 at 07:11:24PM +0300, Vasiliy Kulikov wrote:
> > If /proc/sys/kernel/modules_disabled is set to 1, then nobody (even full
> > root) may not read/write arbitrary kernel memory.  In spite of it,
> > hibernation allows anyone with an access to either /dev/snapshot or
> > /sys/power/ make the full snapshot of the system.  This snapshot may be
> > freely changed and uploaded back.
> 
> Ah, yes please. I'd like to try to have ways to close all the
> "intentional" arbitrary memory writing interfaces.

They are not exactly arbitrary and I'd like to see a plausible attack
scenario using the hibernation interface as is (assuming you're not a
full root at least).

> Hooking it to modules_disable seems as good as any other toggle.

You're kidding, aren't you?

> Still waiting to hear
> anything on this: http://article.gmane.org/gmane.linux.acpi.devel/49471

I personally don't think it's a good idea, but I'm not the maintainer of that
code.

Thanks,
Rafael
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