linux-kernel - Re: [PATCH 0/4][RFC v2] Introduce the in-kernel hibernation encryption

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Date:   Tue, 31 Jul 2018 01:04:15 +0800
From:   joeyli <jlee@...e.com>
To:     Oliver Neukum <oneukum@...e.com>
Cc:     Yu Chen <yu.c.chen@...el.com>, Pavel Machek <pavel@....cz>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Eric Biggers <ebiggers@...gle.com>,
        Theodore Ts o <tytso@....edu>,
        Stephan Mueller <smueller@...onox.de>,
        Denis Kenzior <denkenz@...il.com>, linux-pm@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gu, Kookoo" <kookoo.gu@...el.com>,
        "Zhang, Rui" <rui.zhang@...el.com>
Subject: Re: [PATCH 0/4][RFC v2] Introduce the in-kernel hibernation
 encryption

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 

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