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

joeyli
2018-07-30T17:04:41Z

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