From: Pavel Machek <pavel@ucw.cz>
Subject: Re: [PATCH 0/4][RFC v2] Introduce the in-kernel hibernation
 encryption
Date: Tue, 24 Jul 2018 15:03:46 +0200
Message-ID: <20180724130110.GA29006@amd>
References: <cover.1531924968.git.yu.c.chen@intel.com>
 <20180718202235.GA4132@amd>
 <20180718235851.GA22170@sandybridge-desktop>
 <20180719110149.GA4679@amd>
 <20180719132003.GA30981@sandybridge-desktop>
 <20180720102532.GA20284@amd>
 <1532346156.3057.11.camel@suse.com>
 <20180723162302.GA4503@sandybridge-desktop>
 <20180724120133.GD26036@amd>
 <1532436474.17797.20.camel@suse.com>
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Cc: Yu Chen <yu.c.chen@intel.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
        Eric Biggers <ebiggers@google.com>,
        "Lee, Chun-Yi" <jlee@suse.com>, Theodore Ts o <tytso@mit.edu>,
        Stephan Mueller <smueller@chronox.de>,
        Denis Kenzior <denkenz@gmail.com>, linux-pm@vger.kernel.org,
        linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
        "Gu, Kookoo" <kookoo.gu@intel.com>,
        "Zhang, Rui" <rui.zhang@intel.com>
To: Oliver Neukum <oneukum@suse.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
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On Tue 2018-07-24 14:47:54, Oliver Neukum wrote:
> On Di, 2018-07-24 at 14:01 +0200, Pavel Machek wrote:
> > Hi!
> >=20
> > > > > >        "There have some functions be locked-down because
> > > > > >        there have no appropriate mechanisms to check the
> > > > > >        integrity of writing data."
> > > > > >        https://patchwork.kernel.org/patch/10476751/
> > > > >=20
> > > > > So your goal is to make hibernation compatible with kernel
> > > > > lockdown? Do your patches provide sufficient security that hibern=
ation
> > > > > can be enabled with kernel lockdown?
> > > >=20
> > > > OK, maybe I am dense, but if the key comes from user space, will th=
at
> > > > be enough?
> > > >=20
> > >=20
> > > Good point, we once tried to generate key in kernel, but people
> > > suggest to generate key in userspace and provide it to the
> > > kernel, which is what ecryptfs do currently, so it seems this
> > > should also be safe for encryption in kernel.
> >=20
> > Safe against what kind of attack? Please describe what kind of
> > security you are trying to provide.
>=20
> Unsigned code must not take over the priviledge level of signed code.
> Hence:
>=20
> 1. Unsigned code must not allowed to read sensitive parts of signed
> code's memory space
>=20
> 2. Unsigned code must not be able to alter the memory space of
> signed code -> snapshots that are changed must not be able to be
> resumed

Ok.

> > I don't think generating key in userspace is good enough for providing
> > guarantees for secure-boot.
>=20
> Why?

Because then, userpace has both key (now) and encrypted image (after
reboot), so it can decrypt, modify, re-encrypt...?

									Pavel
--=20
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo=
g.html

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