Injecting public keys into FTDs for FIT verification

[Simon Glass]

Hi,

On Fri, 5 Nov 2021 at 07:04, Jan Kiszka <jan.kiszka at siemens.com> wrote:
>
> On 05.11.21 13:42, Jan Kiszka wrote:
> > On 05.11.21 11:28, Rasmus Villemoes wrote:
> >> On 05/11/2021 11.16, Jan Kiszka wrote:
> >>> Hi all,
> >>>
> >>> in order to use CONFIG_FIT_SIGNATURE and also
> >>> CONFIG_SPL_FIT_SIGNATURE, a public key needs to be placed into the
> >>> control FDT. So far, I only found mkimage being able to do that during
> >>> FIT image signing. That is fairly unhandy and often incompatible with
> >>> how firmware is built & signed vs. how the lifecycle of the artifacts to
> >>> be loaded and verified look like. Is there really no other way than
> >>> mkimage -K?
> >>>
> >>> I'm currently considering to derive a tool that, given a public key
> >>> (which is easy to hand around, compared to the private key needed for
> >>> signing), injects them into a FDT. Then I would hook that up as generic
> >>> feature for U-Boot builds, enriching all control FTDs already during the
> >>> first build with this when requested.
> >>>
> >>> Am I missing an even simpler approach?
> >>
> >> You're not missing an existing upstream simpler approach, but it's
> >> certainly an itch that others have had [1] [2]. My latest attempt
> >>
> >> https://lore.kernel.org/u-boot/20210928085651.619892-1-rasmus.villemoes@prevas.dk/
> >>
>
> Looking at this path: I would also need it for SPL, so that SPL can
> validate the container for the main U-Boot. Seems that is missing here,
> isn't it?
>
> Jan
>
> >> does now have an R-b by Simon, so now I'm just waiting for that to
> >> actually make it into master. I have the script(s) that will convert a
> >> public key to a .dtsi fragment, and I'm happy to share that.
> >>
> >
> > Cool, that would be very welcome!

What I'd really like is a separate tool. It was sent as attachments
but we are waiting for the author to send them as patches on the
thread "Introduce CONFIG_DEVICE_TREE_INCLUDES".

BTW, Rasmus, some documentation on this patch would be helpful.

Regards,
Simon


> >
> > Jan
> >
> >> Rasmus
> >>
> >> [1]
> >> https://lore.kernel.org/u-boot/CAO5Uq5TyTMacERo01weTEda-5X4Fx-VUoYFHa=mBYhW-RvmVSQ@mail.gmail.com/
> >> [2]
> >> https://lore.kernel.org/u-boot/94d75c521aed46dbb54a8275be2f529e@kaspersky.com/
> >>
> >
>
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