On Fri, 26 Apr 2019 at 12:36, Bryan O'Donoghue <[email protected]>
wrote:

>
>
> On 26/04/2019 10:29, Ilias Apalodimas wrote:
> >> I’d rather see Secure Boot image authentication implemented generically
> for all u-boot platforms, even when secure world variable updates are not
> available.
> > Akashi and Sughosh already have code on that. It's not 100% complete or
> tested
> > yet, but the basic concept works.
>
> Is that to say that u-boot will provide, Runtime services for EFI
> capsule update ?
>
That shall be one of the few runtime services supported as well as get/set
variables.

>
> Is that the current POR ?
>
Yes

>
> Maybe its a stupid question but, on x86 the way this works is you submit
> a capsule to the EFI runtime service, reboot and the EFI firmware does
> your update.
>
> On Arm then the flow is
>
> #1
> Linux capsule update -> reboot -> BootROM -> [BL31],[BL32 TEE] -> u-boot
>
> and u-boot performs the update ? The bracketed items [] being optional ?
>
> only for the untrusted parts. S-EL3 shall update or validate the updates.

> A question then would it not also be possible to bypass capsule
> submission in Linux ?
>
> In a different thread (EFIBootguard: do you follow this one too?), someone
proposed that in the context of A/B partitions, Linux software agent
updates a partition and the reboot cycle validates if it accepts. This may
be a flow but I see issues in this approach that need a lot of discussion.

> #2
> Linux -> reboot -> BootROM -> [BL31],[BL32 TEE] -> u-boot
>
> with u-boot looking for say /boot/FirmwareUpdate.cap
>
> In the second case, there's no need from Runtime services is why I ask.
>
> ---
> bod
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-- 
François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group*
T: +33.67221.6485
[email protected] | Skype: ffozog
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