[PATCH] efi_loader: Allow also empty capsule to be process

[AKASHI Takahiro]

Hi Michal, Sughosh,

On Wed, Jul 26, 2023 at 06:36:56PM +0200, Michal Simek wrote:
> 
> 
> On 7/26/23 15:07, Ilias Apalodimas wrote:
> > Hi all
> > 
> > [...]
> > 
> > > > > 
> > > > 
> > > > Hello Sugosh,
> > > > 
> > > > fwu_empty_capsule() detects an empty capsule as one with a GUID
> > > > fwu_guid_os_request_fw_revert or fwu_guid_os_request_fw_accept.
> > > > 
> > > > I am not aware of a requirement in the UEFI specification to treat
> > > > capsules read from file in a different way than capsules passed via
> > > > UpdateCapsule(). Is there any reason why UpdateCapsule() should not
> > > > process an empty capsule when called from a boot-time EFI application?
> > > 
> > > Here is a story behind efi_update_capsule():
> > > ===
> > > commit a6aafce494ab
> > > Author: Masami Hiramatsu <masami.hiramatsu at linaro.org>
> > > Date:   Wed Feb 16 15:15:42 2022 +0900
> > > 
> > >      efi_loader: use efi_update_capsule_firmware() for capsule on disk
> > > ===
> > > 
> > > I still believe that this is a valid change, but we should have
> > > moved 'capsule->capsule_guid' check into efi_update_capsule_firmware()
> > > at the same time.
> > 
> > I agree with Akashi-san here.  I am also fine with this patchset since
> > running the A/B update from an EFI app should work. But can we do a v2
> > with 2 patches?
> > #1 move the capsule check along with the empty capsule checks in
> > efi_update_capsule_firmware()
> > #2 fix the a/b updates via the runtime calls and adjust the commit
> > message accordingly, explaining why this change is needed?
> 
> Can someone from Linaro create v2 on this?
> I just wanted to pointed to it.

Yes, I posted "efi_loader: capsule: enforce guid check in api and
capsule_on_disk".
Since I didn't run any test against A/B update, can you please
confirm that this patch works in your environment?

Unlike Ilias suggested, I made a single patch because an empty
capsule will be handled any way at the beginning of
efi_capsule_update_firmware() and we process only normal capsules
after that.

-Takahiro Akashi

> Thanks,
> Michal