linux-kernel - Re: [PATCH v5 3/3] efi: Add tee-based EFI variable driver

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Message-ID: <871ece13-7d6e-44d4-3bda-317658202f6f@siemens.com>
Date:   Wed, 7 Jun 2023 21:46:02 +0200
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Ilias Apalodimas <ilias.apalodimas@...aro.org>
Cc:     Sumit Garg <sumit.garg@...aro.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Masahisa Kojima <masahisa.kojima@...aro.org>,
        Jens Wiklander <jens.wiklander@...aro.org>,
        linux-kernel@...r.kernel.org, op-tee@...ts.trustedfirmware.org,
        Johan Hovold <johan+linaro@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        linux-efi@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org,
        "Su, Bao Cheng (RC-CN DF FA R&D)" <baocheng.su@...mens.com>
Subject: Re: [PATCH v5 3/3] efi: Add tee-based EFI variable driver

On 07.06.23 20:17, Ilias Apalodimas wrote:
> On Wed, 7 Jun 2023 at 20:14, Jan Kiszka <jan.kiszka@...mens.com> wrote:
>>
>> On 07.06.23 18:59, Ilias Apalodimas wrote:
>>> On Wed, 7 Jun 2023 at 19:09, Ilias Apalodimas
>>> <ilias.apalodimas@...aro.org> wrote:
>>>>
>>>> Hi Jan,
>>>>
>>>> [...]
>>>>>>>> No I don't, this will work reliably without the need to remount the efivarfs.
>>>>>>>> As you point out you will still have this dependency if you end up
>>>>>>>> building them as modules and you manage to mount the efivarfs before
>>>>>>>> those get inserted.  Does anyone see a reasonable workaround?
>>>>>>>> Deceiving the kernel and making the bootloader set the RT property bit
>>>>>>>> to force the filesystem being mounted as rw is a nasty hack that we
>>>>>>>> should avoid.  Maybe adding a kernel command line parameter that says
>>>>>>>> "Ignore the RTPROP I know what I am doing"?  I don't particularly love
>>>>>>>> this either, but it's not unreasonable.
>>>>>>>
>>>>>>> In the context of https://github.com/OP-TEE/optee_os/issues/6094,
>>>>>>> basically this issue mapped on reboot/shutdown, I would really love to
>>>>>>> see the unhandy tee-supplicant daemon to be overcome.
>>>>>>
>>>>>> I have seen this error before and it has been on my todo list. So I
>>>>>> have tried to fix it here [1]. Feel free to test it and let me know if
>>>>>> you see any further issues.
>>>>>>
>>>>>> [1] https://lkml.org/lkml/2023/6/7/927
>>>>>>
>>>>>
>>>>> Ah, nice, will test ASAP!
>>>>>
>>>>> Meanwhile more food: I managed to build a firmware that was missing
>>>>> STMM. But the driver loaded, and I got this:
>>>>
>>>> Thanks for the testing. I'll try to reproduce it locally and get back to you
>>>
>>> Can you provide a bit more info on how that was triggered btw? I would
>>> be helpful to know
>>>
>>> - OP-TEE version
>>
>> Today's master, 145953d55.
>>
>>> - was it compiled as a module or built-in?
>>
>> Sorry, not sure anymore, switching back and forth right now. I think it
>> was built-in.
>>
>>> - was the supplicant running?
>>
>> Yes.
>>
> 
> Ok thanks, that helps.  I guess this also means U-Boot was compiled to
> store the variables in a file in the ESP instead of the RPMB right?
> Otherwise, I can't see how the device booted in the first place.

U-Boot was not configured to perform secure booting in this case. It had
RPMB support enabled, just didn't have to use it.

Jan

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