linux-kernel - Re: [TuxOnIce-devel] RFC: Suspend-to-ram cold boot protection by encrypting page cache

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Message-ID: <20090709101433.GG10937@elf.ucw.cz>
Date:	Thu, 9 Jul 2009 12:14:33 +0200
From:	Pavel Machek <pavel@....cz>
To:	Jeremy Maitin-Shepard <jeremy@...emyms.com>
Cc:	Nigel Cunningham <ncunningham@...a.org.au>,
	tuxonice-devel@...ts.tuxonice.net, linux-kernel@...r.kernel.org,
	Rafael Wysocki <rjw@...k.pl>
Subject: Re: [TuxOnIce-devel] RFC: Suspend-to-ram cold boot protection by
	encrypting page cache

On Wed 2009-07-08 04:09:41, Jeremy Maitin-Shepard wrote:
> Pavel Machek <pavel@....cz> writes:
> 
> > On Wed 2009-07-08 03:47:53, Jeremy Maitin-Shepard wrote:
> >> Pavel Machek <pavel@....cz> writes:
> >> 
> >> [snip]
> >> 
> >> > I believe uswsusp could be used rather easily. Just modify s2disk to
> >> > encrypt image in ram without writing it out, then decrypt it from ram
> >> > and resume... it should be interesting hack.
> >> 
> >> As far as I understand, that would be completely useless since the image
> >> that would be encrypted would just be a copy of what would still remain
> >> in memory.
> 
> > Yes... so next step would be kernel call that would erase all the
> > pagecache and anonymous pages. You would still leave some data in
> > kernel structures, but that would be quite hard to fix. 
> 
> Okay.  (This does still require the same assumption as TuxOnIce
> regarding the page cache, though.)

(Not sure; clearing the page cache could be done atomically, from
interrupts disabled. But I'm no mm expert.)
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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