Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 3 Aug 2018 11:37:02 +0800
From:   Yu Chen <yu.c.chen@intel.com>
To:     joeyli <jlee@suse.com>
Cc:     Oliver Neukum <oneukum@suse.com>, Pavel Machek <pavel@ucw.cz>,
        "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
        Eric Biggers <ebiggers@google.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>
Subject: Re: [PATCH 0/4][RFC v2] Introduce the in-kernel hibernation
 encryption
Message-ID: <20180803033702.GB416@sandybridge-desktop>
References: <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>
 <1532590246.7411.3.camel@suse.com>
 <20180726081404.GG4244@linux-l9pv.suse>
 <20180730170415.GQ4244@linux-l9pv.suse>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20180730170415.GQ4244@linux-l9pv.suse>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Joey,
On Tue, Jul 31, 2018 at 01:04:15AM +0800, joeyli wrote:
> Hi all,
> 
> On Thu, Jul 26, 2018 at 04:14:04PM +0800, joeyli wrote:
> > On Thu, Jul 26, 2018 at 09:30:46AM +0200, Oliver Neukum wrote:
> > > On Di, 2018-07-24 at 00:23 +0800, Yu Chen wrote:
> > > > 
> > > > 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.
> > > > https://www.spinics.net/lists/linux-crypto/msg33145.html
> > > > Thus Chun-Yi's signature can use EFI key and both the key from
> > > > user space.
> > > 
> > > Hi,
> > > 
> > > ecryptfs can trust user space. It is supposed to keep data
> > > safe while the system is inoperative. The whole point of Secure
> > > Boot is a cryptographic system of trust that does not include
> > > user space.
> > > 
> > > I seriously doubt we want to use trusted computing here. So the
> > > key needs to be generated in kernel space and stored in a safe
> > > manner. As we have a saolution doing that, can we come to ausable
> > > synthesis?
> > > 
> > > 	Regards
> > > 		Oliver
> > 
> > Crurently there have two solutions, they are trusted key and EFI key.
> > Both of them are generated in kernel and are not visible in user space.
> > 
> > The trusted key is generated by kernel then sealed by the TPM's
> > SRK. So the trusted key can be stored in anywhere then be enrolled
> > to kernel when we need it. EVM already uses it.
> > 
> > The EFI key is Jiri Kosina's idea. It is stored in boot services
> > variable, which means that it can only be access by signed EFI binary
> > (e.g. signed EFI boot stub) when secure boot be enabled. SLE applied
> > this solution a couple of years.
> > 
> > I am working on put the EFI key to key retention service. Then
> > EFI key can be a master key of encrypted key. EVM can also use
> > it: 
> > https://github.com/joeyli/linux-s4sign/commit/bae39460393ada4c0226dd07cd5e3afcef86b71f
> > https://github.com/joeyli/linux-s4sign/commit/f552f97cc3cca5acd84f424b7f946ffb5fe8e9ec
> > 
> > That's why I want to use key retention service in hibernation
> > encryption/authentication. Which means that we can use key
> > API to access trusted key and EFI key.  
> >
> 
> Here is a proof of concept for using the key retention service
> to encrypt/sign snapshot image. It's using EFI key now, I will
> add encrypted key support in the key handler later:
>     https://github.com/joeyli/linux-s4sign/commit/6311e97038974bc5de8121769fb4d34470009566 
> 
Thanks for the work, I have two questions here:
1. Could you please describe a little more about the scenario on
   how the user could use the secret key for hibernation encryption?
   A requirement is that, the user should provide a passphrase(for key derivation, i.e.)
   during resume. I was thinking how user could interact with
   the security key mechanism here.

2. The generation of secret key in EFI boot environment is
   using a non standard derivation method in generate_secret_key(),
   I'm not sure if this is safe enough. This is why we tried to put
   PBKDF2 into kernel at first and leave it to the user space then.

Best,
Yu

> My next step is that cleaning up the my EFI key type patches and
> submit it to EFI/keys subsystem ASAP. Then I will clean up
> my hibernation encryption/authentication solution for reviewing.
> 
> Thanks
> Joey Lee