linux-kernel - Re: [PATCH 0/3] dm-crypt: Adds support for wiping key when doing suspend/hibernation

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Message-ID: <20150406130045.GA18583@redhat.com>
Date:	Mon, 6 Apr 2015 09:00:46 -0400
From:	Mike Snitzer <snitzer@...hat.com>
To:	Pali Rohár <pali.rohar@...il.com>
Cc:	Alasdair Kergon <agk@...hat.com>, Neil Brown <neilb@...e.de>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	dm-devel@...hat.com, linux-raid@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 0/3] dm-crypt: Adds support for wiping key when doing
 suspend/hibernation

On Sun, Apr 05 2015 at  1:20pm -0400,
Pali Rohár <pali.rohar@...il.com> wrote:

> This patch series increase security of suspend and hibernate actions. It allows
> user to safely wipe crypto keys before suspend and hibernate actions starts
> without race conditions on userspace process with heavy I/O.
> 
> To automatically wipe cryto key for <device> before hibernate action call:
> $ dmsetup message <device> 0 key wipe_on_hibernation 1
> 
> To automatically wipe cryto key for <device> before suspend action call:
> $ dmsetup message <device> 0 key wipe_on_suspend 1
> 
> (Value 0 after wipe_* string reverts original behaviour - to not wipe key)

Can you elaborate on the attack vector your changes are meant to protect
against?  The user already authorized access, why is it inherently
dangerous to _not_ wipe the associated key across these events?
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