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

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Message-ID: <20110304203201.GA22079@elf.ucw.cz>
Date:	Fri, 4 Mar 2011 21:32:02 +0100
From:	Pavel Machek <pavel@....cz>
To:	Vasiliy Kulikov <segoon@...nwall.com>
Cc:	linux-kernel@...r.kernel.org, security@...nel.org,
	Len Brown <len.brown@...el.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	linux-pm@...ts.linux-foundation.org
Subject: Re: [PATCH] power: disable hibernation if module loading is
 disabled

On Fri 2011-03-04 19:11:24, 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.

module loading has nothing to do with hibernation, and hibernation
already checks for CAP_ADMIN or something similary strong. I don't see
why this new check is needed.

In fact, you are probably breaking someone's setup right now.

> +	if (modules_disabled)
> +		return -EPERM;
> +
>  	error = platform_begin(platform_mode);

Hmm. How is this supposed to work with CONFIG_MODULES off?

NAK.
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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