Re: [PATCH v39 15/24] x86/sgx: Add SGX_IOC_ENCLAVE_PROVISION

[Jarkko Sakkinen]

On Tue, Oct 20, 2020 at 02:19:26PM -0700, Dave Hansen wrote:
> On 10/2/20 9:50 PM, Jarkko Sakkinen wrote:
> > + * Failure to explicitly request access to a restricted attribute will cause
> > + * sgx_ioc_enclave_init() to fail.  Currently, the only restricted attribute
> > + * is access to the PROVISION_KEY.
> 
> Could we also justify why access is restricted, please?  Maybe:
> 
> 	Access is restricted because PROVISION_KEY is burned uniquely
> 	into each each processor, making it a perfect unique identifier
> 	with privacy and fingerprinting implications.
> 
> Are there any other reasons for doing it this way?

AFAIK, if I interperet the SDM correctl, PROVISION_KEY and
PROVISION_SEALING_KEY also have random salt added, i.e. they change
every boot cycle.

There is "RAND = yes" on those keys in Table 40-64 of Intel SDM volume
3D :-)

/Jarkko