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

Oliver Neukum
2018-07-24T12:55:38Z

On Di, 2018-07-24 at 14:01 +0200, Pavel Machek wrote:
> Hi!
>
> > > > > "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/
> > > >
> > > > So your goal is to make hibernation compatible with kernel
> > > > lockdown? Do your patches provide sufficient security that hibernation
> > > > can be enabled with kernel lockdown?
> > >
> > > OK, maybe I am dense, but if the key comes from user space, will that
> > > be enough?
> > >
> >
> > 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.
>
> Safe against what kind of attack? Please describe what kind of
> security you are trying to provide.

Unsigned code must not take over the priviledge level of signed code.
Hence:

1. Unsigned code must not allowed to read sensitive parts of signed
code's memory space

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

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

Why?

Regards
Oliver