On Thu, May 30, 2019 at 12:20:45PM -0700, Andy Lutomirski wrote:

On Thu, May 30, 2019 at 11:01 AM Sean Christopherson
[off-list ref] wrote:

quoted

On Thu, May 30, 2019 at 09:14:10AM -0700, Andy Lutomirski wrote:

quoted

Enclave file -- that is, the file backing the vma from which the data is loaded.

It wasn't explicitly called out in Andy's proposal(s), but the idea is
that the SGX driver would effectively inherit permissions from the source
VMA (EADD needs a source for the initial value of the encave page).

I actually meant for it to *not* work like this.  I don't want the
source VMA to have to be VM_EXEC.  I think the LSM should just check
permissions on ->vm_file.

But if ->vm_file is NULL, i.e. the enclave is not backed by a file,
then PROCESS__EXECMEM is required (or more likely, ENCLAVE__EXECMEM).

In practice, it's the same net effect of using sigstruct as a proxy,
i.e. *something* has to get to the file system to avoid EXECMEM.  But
putting the entire enclave to the filesystem seems like a heaver lift
than dumping the sigstruct.

And if sigstruct needs to be in the file system for
security_enclave_create/init()...