[U-Boot] [PATCH 1/3] tpm: Add function to load keys via their parent's SHA1 hash

[Mario Six]

On Wed, Mar 22, 2017 at 2:05 PM, Simon Glass <sjg at chromium.org> wrote:
> On 20 March 2017 at 03:28, Mario Six <mario.six at gdsys.cc> wrote:
>> If we want to load a key into a TPM, we need to know the designated parent
>> key's handle, so that the TPM is able to insert the key at the correct place in
>> the key hierarchy.
>>
>> However, if we want to load a key whose designated parent key we also
>> previously loaded ourselves, we first need to memorize this parent key's handle
>> (since the handles for the key are chosen at random when they are inserted into
>> the TPM). If we are, however, unable to do so, for example if the parent key is
>> loaded into the TPM during production, and its child key during the actual
>> boot, we must find a different mechanism to identify the parent key.
>>
>> To solve this problem, we add a function that allows U-Boot to load a key into
>> the TPM using their designated parent key's SHA1 hash, and the corresponding
>> auth data.
>>
>> Signed-off-by: Mario Six <mario.six at gdsys.cc>
>> ---
>>  cmd/tpm.c           | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
>>  drivers/tpm/Kconfig |  8 ++++++++
>>  include/tpm.h       | 12 ++++++++++++
>>  lib/tpm.c           | 40 ++++++++++++++++++++++++++++++++++++++++
>>  4 files changed, 109 insertions(+)
>
> Reviewed-by: Simon Glass <sjg at chromium.org>
>
> Perhaps you don't need a new Kconfig option? Is that to save code space?
>
>

Yes, it's primarily to save code space. I haven't really investigated how much
this option does impact the overall size, but since every recent addition to
the TPM library was guarded with a new Kconfig option, I thought it was prudent
to emulate that.

If you think it's overkill, I can drop the option, and just have it
compiled in by default.

Thanks, and best regards,

Mario