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

Haitao Huang
2020-09-02T18:40:59Z

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