Re: [PATCH v3 1/3] crypto: mxs-dcp: Add support for hardware provided keys

[Jarkko Sakkinen]

On Wed Sep 27, 2023 at 9:25 AM EEST, David Gstir wrote:
> Jarkko,
>
> > On 25.09.2023, at 17:22, Jarkko Sakkinen <jarkko@xxxxxxxxxx> wrote:
> > 
> > On Mon Sep 18, 2023 at 5:18 PM EEST, David Gstir wrote:
> >> DCP is capable to performing AES with hardware-bound keys.
> >> These keys are not stored in main memory and are therefore not directly
> >> accessible by the operating system.
> >> 
> >> So instead of feeding the key into DCP, we need to place a
> >> reference to such a key before initiating the crypto operation.
> >> Keys are referenced by a one byte identifiers.
> > 
> > Not sure what the action of feeding key into DCP even means if such
> > action does not exists.
> > 
> > What you probably would want to describe here is how keys get created
> > and how they are referenced by the kernel.
> > 
> > For the "use" part please try to avoid academic paper style long
> > expression starting with "we" pronomine.
> > 
> > So the above paragraph would normalize into "The keys inside DCP
> > are referenced by one byte identifier". Here of course would be
> > for the context nice to know what is this set of DCP keys. E.g.
> > are total 256 keys or some subset?
> > 
> > When using too much prose there can be surprsingly little digestable
> > information, thus this nitpicking.
>
> Thanks for reviewing that in detail! I’ll rephrase the commit
> messages on all patches to get rid of the academic paper style.
>
>
> > 
> >> DCP supports 6 different keys: 4 slots in the secure memory area,
> >> a one time programmable key which can be burnt via on-chip fuses
> >> and an unique device key.
> >> 
> >> Using these keys is restricted to in-kernel users that use them as building
> >> block for other crypto tools such as trusted keys. Allowing userspace
> >> (e.g. via AF_ALG) to use these keys to crypt or decrypt data is a security
> >> risk, because there is no access control mechanism.
> > 
> > Unless this patch has anything else than trusted keys this should not
> > be an open-ended sentence. You want to say roughly that DCP hardware
> > keys are implemented for the sake to implement trusted keys support,
> > and exactly and only that.
> > 
> > This description also lacks actions taken by the code changes below,
> > which is really the beef of any commit description.
>
> You’re right. I’ll add that.

Yup, I'm just doing my part of the job, as I'm expected to do it :-)
Thanks for understanding.

> Thanks,
> - David

BR, Jarkko