Re: [PATCH v33 11/21] x86/sgx: Linux Enclave Driver

[Haitao Huang]

On Wed, 02 Sep 2020 11:10:12 -0500, Sean Christopherson  
<sean.j.christopherson@xxxxxxxxx> wrote:

> On Tue, Sep 01, 2020 at 10:06:32PM -0500, Haitao Huang wrote:
> > On Fri, 03 Jul 2020 22:31:10 -0500, Jarkko Sakkinen
> > <jarkko.sakkinen@xxxxxxxxxxxxxxx> wrote:
> >
> > > On Wed, Jul 01, 2020 at 08:59:02PM -0700, Sean Christopherson wrote:
> > > > On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> > > > > +static int sgx_validate_secs(const struct sgx_secs *secs,
> > > > > +			     unsigned long ssaframesize)
> > > > > +{
> > > > > +	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
> > > > > +		return -EINVAL;
> > > > > +
> > > > > +	if (secs->base & (secs->size - 1))
> > > > > +		return -EINVAL;
> > > > > +
> > > > > +	if (secs->miscselect & sgx_misc_reserved_mask ||
> > > > > +	    secs->attributes & sgx_attributes_reserved_mask ||
> > > > > +	    secs->xfrm & sgx_xfrm_reserved_mask)
> > > > > +		return -EINVAL;
> > > > > +
> > > > > +	if (secs->attributes & SGX_ATTR_MODE64BIT) {
> > > > > +		if (secs->size > sgx_encl_size_max_64)
> > > > > +			return -EINVAL;
> > > > > +	} else if (secs->size > sgx_encl_size_max_32)
> > > > > +		return -EINVAL;
> > > >
> > > > These should be >=, not >, the SDM uses one of those fancy ≥  
> > ligatures.
> > > >
> > > > Internal versions use more obvious pseudocode, e.g.:
> > > >
> > > >     if ((DS:TMP_SECS.ATTRIBUTES.MODE64BIT = 1) AND
> > > >         (DS:TMP_SECS.SIZE AND (~((1 << CPUID.18.0:EDX[15:8]) – 1)))
> > > >     {
> > > >         #GP(0);
> > >
> > > Updated as:
> > >
> > > static int sgx_validate_secs(const struct sgx_secs *secs)
> > > {
> > > 	u64 max_size = (secs->attributes & SGX_ATTR_MODE64BIT) ?
> > > 		       sgx_encl_size_max_64 : sgx_encl_size_max_32;
> > >
> > > 	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
> > > 		return -EINVAL;
> > >
> > > 	if (secs->base & (secs->size - 1))
> > > 		return -EINVAL;
> > >
> > > 	if (secs->miscselect & sgx_misc_reserved_mask ||
> > > 	    secs->attributes & sgx_attributes_reserved_mask ||
> > > 	    secs->xfrm & sgx_xfrm_reserved_mask)
> > > 		return -EINVAL;
> > >
> > > 	if (secs->size >= max_size)
> > > 		return -EINVAL;
> > >
> >
> > This should be > not >=. Issue raised and fixed by Fábio Silva for  
> > ported
> > patches for OOT SGX support:
> > https://github.com/intel/SGXDataCenterAttestationPrimitives/pull/123
> >
> > I tested and verified with Intel arch, the comparison indeed should be  
> > >.
>
> And this is a confirmed SDM bug, correct?

yes, the pseudo code for ECREATE is inaccurate and inconsistent with the  
CPUID spec. The latter is correct.
Haitao