On Thu, May 30, 2019 at 11:01:10AM -0700, Sean Christopherson wrote: > - Requires enclave builder to mark enclave pages executable in the > non-enclave VMAs, which may unnecessarily require EXECMOD on the > source file, or even worse, EXECMEM, and potentially increases the > attack surface since the file must be executable. Enclave builder marks *non-enclave pages*? Not following. > W^X handling: > - mmap() to /dev/sgx/enclave only allowed with PROT_NONE, i.e. force > userspace through mprotect() to simplify the kernel implementation. > - Add vm_ops mprotect() ops hook (I'll refer to SGX's implementation > as SGX.mprotect()) > - Take explicit ALLOW_WRITE at ADD_REGION, a.k.a. EADD > - ADD_REGION also used to describe EAUG region (tentatively for SGX2). > - Track "can be written at some point in time (past or future)" as > ALLOW_WRITE (to avoid confusiong with MAY_WRITE). A priori knowledge > of writability avoids having to track/coordinate PROT_WRITE across > VMAs and MMs. Still not sure why you want to use vm_ops instead of file_operations. The approach I've been proposing earlier in this email thread before these new proposals can be summarized from hook perspective as: - Allow mmap() only before ECREATE and require it to be size of the ELRANGE (ECREATE ioctl would check this). This would be with PROT_NONE. - Disallow mprotect() before EINIT. Requires a new callback to file_operations like mmap() has. - After EINIT check for each mprotect() that it matches the permissions of underlying enclave pages. Disallow mmap() after EINIT. /Jarkko
