SGX vs LSM (Re: [PATCH v20 00/28] Intel SGX1 support)

[Sean Christopherson]

On Fri, May 24, 2019 at 09:43:27AM -0700, Andy Lutomirski wrote:
> On Fri, May 24, 2019 at 12:24 AM Xing, Cedric <cedric.xing at intel.com> wrote:
> > /**
> >  * Summary:
> >  * - The enclave file resembles a shared object that contains RO/RX/RW segments
> >  * - FILE__* are assigned to /dev/sgx/enclave, to determine acceptable permissions to mmap()/mprotect(), valid combinations are
> >  *   + FILE__READ - Allow SGX1 enclaves only
> >  *   + FILE__READ|FILE__WRITE - Allow SGX2 enclaves to expand data segments (e.g. heaps, stacks, etc.)
> 
> I think this is a non-starter :(  FILE__WRITE also means that you can
> write to the file, and the admin / policy author will almost never
> want to allow that.

Why would FILE__WRITE on /dev/sgx/enclave be a problem?  An actual
write to /dev/sgx/enclave would yield -EINVAL, no?