linux-kernel - Re: [PATCH v2 3/3] dm-crypt: Adds support for wiping key when doing suspend/hibernation

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Date:	Tue, 28 Jul 2015 16:48:12 +0200
From:	Pali Rohár <pali.rohar@...il.com>
To:	Pavel Machek <pavel@....cz>
Cc:	Alasdair Kergon <agk@...hat.com>,
	Mike Snitzer <snitzer@...hat.com>, Neil Brown <neilb@...e.de>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <len.brown@...el.com>, dm-devel@...hat.com,
	linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 3/3] dm-crypt: Adds support for wiping key when doing
 suspend/hibernation

On Tuesday 28 July 2015 16:44:19 Pavel Machek wrote:
> On Sun 2015-06-21 13:20:34, Pali Rohár wrote:
> > This patch adds dm message commands and option strings to optionally wipe key
> > from dm-crypt device before entering suspend or hibernate state.
> > 
> > Before key is wiped dm device must be suspended. To prevent race conditions with
> > I/O and userspace processes, wiping action must be called after processes are
> > freezed. Otherwise userspace processes could start reading/writing to disk after
> > dm device is suspened and freezing processes before suspend/hibernate action
> > will fail.
> 
> Are you sure this is enough?
> 
> We still may need to allocate memory after userspace is frozen, and
> that could mean writing dirty buffers out to make some memory free...
> 
> 								Pavel
> 								

Hm... good question. Maybe it is needed to also flush all buffers?

-- 
Pali Rohár
pali.rohar@...il.com
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