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

From: "Pali Rohár" <pali.rohar@gmail.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: Mike Snitzer <snitzer@redhat.com>,
	Alasdair Kergon <agk@redhat.com>, Neil Brown <neilb@suse.de>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Len Brown <len.brown@intel.com>,
	dm-devel@redhat.com, linux-raid@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH 0/3] dm-crypt: Adds support for wiping key when doing suspend/hibernation
Date: Thu, 23 Apr 2015 19:02:11 +0200	[thread overview]
Message-ID: <20150423170211.GI7646@pali> (raw)
In-Reply-To: <20150414065016.GB20597@amd>

On Tuesday 14 April 2015 08:50:16 Pavel Machek wrote:
> Hi!
> 
> > > > > > So proper way is to wipe luks crypto keys *after* userspace processes
> > > > > > are freezed.
> > > > > 
> > > > > I know you believe that I'm just not accepting that at face value.
> > > > 
> > > > If disks are synced before any DM suspend operation then we have higher
> > > > chance of preventing data corruption.
> > > 
> > > disks are already synced as part of the DM suspend operation!
> > > 
> > 
> > Yes, but part of hibernate operation is also sync call.
> 
> Yes. Maybe that was a mistake.
> 

I think not. I do not see any reason why system should not sync disks...

> > > > I still think that correct order is only:
> > > > 
> > > > * freeze processes (which doing continous I/O)
> > > > * fs & disk sync
> > > > * DM suspend
> > > > * wipe crypto keys
> > > > * enter hibernate
> > > 
> > > I just don't think that extreme is _required_ to have a hibernate/resume
> > > that incorporates dm-crypt key wiping.
> > 
> > Ok, and what other developers think?
> 
> If someone can fix freezer to work with LUKS stopped, that would be a 
> good thing. Can you do it, Mike? Then we can look if it works well
> enough for Pali.
> 

Its not only LUKS devices. Its for all dm devices when are suspended.

> But that might be too hard / impossible. And at that point, I think
> Pali's patch is right thing to do.
> 									Pavel

Yes I think it is hard too...

-- 
Pali Rohár
pali.rohar@gmail.com