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

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Message-ID: <20150407135552.GA32694@agk-dp.fab.redhat.com>
Date:	Tue, 7 Apr 2015 14:55:52 +0100
From:	Alasdair G Kergon <agk@...hat.com>
To:	Pali Rohár <pali.rohar@...il.com>
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>, Pavel Machek <pavel@....cz>,
	linux-raid@...r.kernel.org, dm-devel@...hat.com,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [dm-devel] [PATCH 3/3] dm-crypt: Adds support for wiping key
	when doing suspend/hibernation

On Sun, Apr 05, 2015 at 07:20:19PM +0200, 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.
 
Try to avoid 0/1 - use descriptive options instead. 
E.g. key wipe_on_hibernation / key retain_on_hibernation  (message)
     wipe_key_on_hiberation ('dmsetup table' - don't forget the reporting interface!)

Have you tested against every state the driver might be in at the time of
suspend/hibernation?

> +static void crypt_suspend_and_wipe_key(struct crypt_config *cc)
> +{
> +	dm_suspend_md(dm_table_get_md(cc->ti->table));

I'm not particularly keen on this - silently ignoring expected error states
like -EINVAL rather than checking first and not calling the function at all
when it's known not to be needed.

Alasdair

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