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

[Jarkko Sakkinen]

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 >.
> 
> Thanks
> Haitao

Thans a lot!

I added this changelog entry to the v37 log:

* Fixed off-by-one error in a size calculation:
  https://github.com/intel/SGXDataCenterAttestationPrimitives/commit/e44cc238becf584cc079aef40b557c6af9a03f38

Given the Boris' earlier feedback I xref every changelog
entry in v37 changelog. Then it is also less time consuming
to spot if something is missing.

/Jarkko