Hi Jarkko, On 4/14/2022 4:19 AM, Jarkko Sakkinen wrote: > On Thu, 2022-04-14 at 14:19 +0300, Jarkko Sakkinen wrote: >> On Wed, 2022-04-13 at 14:10 -0700, Reinette Chatre wrote: >>> In the initial (SGX1) version of SGX, pages in an enclave need to be >>> created with permissions that support all usages of the pages, from the >>> time the enclave is initialized until it is unloaded. For example, >>> pages used by a JIT compiler or when code needs to otherwise be >>> relocated need to always have RWX permissions. >>> >>> SGX2 includes a new function ENCLS[EMODPR] that is run from the kernel >>> and can be used to restrict the EPCM permissions of regular enclave >>> pages within an initialized enclave. >>> >>> Introduce ioctl() SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS to support >>> restricting EPCM permissions. With this ioctl() the user specifies >>> a page range and the EPCM permissions to be applied to all pages in >>> the provided range. ENCLS[EMODPR] is run to restrict the EPCM >>> permissions followed by the ENCLS[ETRACK] flow that will ensure >>> no cached linear-to-physical address mappings to the changed >>> pages remain. >>> >>> It is possible for the permission change request to fail on any >>> page within the provided range, either with an error encountered >>> by the kernel or by the SGX hardware while running >>> ENCLS[EMODPR]. To support partial success the ioctl() returns an >>> error code based on failures encountered by the kernel as well >>> as two result output parameters: one for the number of pages >>> that were successfully changed and one for the SGX return code. >>> >>> The page table entry permissions are not impacted by the EPCM >>> permission changes. VMAs and PTEs will continue to allow the >>> maximum vetted permissions determined at the time the pages >>> are added to the enclave. The SGX error code in a page fault >>> will indicate if it was an EPCM permission check that prevented >>> an access attempt. >>> >>> No checking is done to ensure that the permissions are actually >>> being restricted. This is because the enclave may have relaxed >>> the EPCM permissions from within the enclave without the kernel >>> knowing. An attempt to relax permissions using this call will >>> be ignored by the hardware. >>> >>> Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx> >> >> Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > > Also for this: > > Tested-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > Thank you very much. Reinette
