Re: [PATCH v1 0/3] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

Sumit Garg
2021-04-01T17:44:03Z

On Thu, 1 Apr 2021 at 19:00, Ahmad Fatoum <a.fatoum@pengutronix.de> wrote:
>
> Hello Richard, Sumit,
>
> On 01.04.21 15:17, Richard Weinberger wrote:
> > Sumit,
> >
> > ----- Ursprüngliche Mail -----
> >> Von: "Sumit Garg" <sumit.garg@linaro.org>
> >> IIUC, this would require support for multiple trusted keys backends at
> >> runtime but currently the trusted keys subsystem only supports a
> >> single backend which is selected via kernel module parameter during
> >> boot.
> >>
> >> So the trusted keys framework needs to evolve to support multiple
> >> trust sources at runtime but I would like to understand the use-cases
> >> first. IMO, selecting the best trust source available on a platform
> >> for trusted keys should be a one time operation, so why do we need to
> >> have other backends available at runtime as well?
> >
> > I thought about devices with a TPM-Chip and CAAM.

In this case why would one prefer to use CAAM when you have standards
compliant TPM-Chip which additionally offers sealing to specific PCR
(integrity measurement) values.

> > IMHO allowing only one backend at the same time is a little over simplified.
>
> It is, but I'd rather leave this until it's actually needed.
> What can be done now is adopting a format for the exported keys that would
> make this extension seamless in future.
>

+1

-Sumit

> Cheers,
> Ahmad
>
> --
> Pengutronix e.K. | |
> Steuerwalder Str. 21 | http://www.pengutronix.de/ |
> 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |