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

From: Jarkko Sakkinen
Date: Tue May 21 2019 - 11:22:28 EST

On Mon, May 20, 2019 at 02:41:05PM +0300, Jarkko Sakkinen wrote:
> On Thu, May 16, 2019 at 05:26:15PM -0700, Andy Lutomirski wrote:
> > Is userspace actually requred to mmap() the enclave prior to EADDing things?
> Nope, not since v20. Here is what I wrote about API to the kernel
> documentation:
> "The enclave life-cycle starts by opening `/dev/sgx/enclave`. After this
> there is already a data structure inside kernel tracking the enclave
> that is initially uncreated. After this a set of ioctl's can be used to
> create, populate and initialize the enclave.
> You can close (if you want) the fd after you've mmap()'d. As long as the
> file is open the enclave stays alive so you might want to do that after
> you don't need it anymore. Even munmap() won't destruct the enclave if
> the file is open. Neither will closing the fd as long as you have
> mmap() done over the fd (even if it does not across the range defined in
> SECS)."
> Enclave can be created and initialized without doing a single mmap()
> call.

We could even disallow mmap() before EINIT done. The way enclave
management internally works right now is quite robust and completely
detached from requiring process address space for anything.