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

Jarkko Sakkinen
2020-07-04T03:31:29Z

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;

/Jarkko