Re: [PATCH v4 5/9] security: keys: trusted: Make sealed key properly interoperable

[Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>]

On Mon, 2019-12-30 at 09:37 -0800, James Bottomley wrote:
> The current implementation appends a migratable flag to the end of a
> key, meaning the format isn't exactly interoperable because the using
> party needs to know to strip this extra byte.  However, all other
> consumers of TPM sealed blobs expect the unseal to return exactly the
> key.  Since TPM2 keys have a key property flag that corresponds to
> migratable, use that flag instead and make the actual key the only
> sealed quantity.  This is secure because the key properties are bound
> to a hash in the private part, so if they're altered the key won't
> load.
> 
> Backwards compatibility is implemented by detecting whether we're
> loading a new format key or not and correctly setting migratable from
> the last byte of old format keys.
> 
> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

I'll stop review here as I'm now quite confident that in high-level
this going to right direction.

For remaining patches:

- Be more explict with the tools. That will also give a framework to
  easily test the patches.
- Same remarks for the code formatting as I gave to earlier.

/Jarkko