On Mon, 2021-12-06 at 13:42 -0800, Reinette Chatre wrote: > Hi Jarkko, > > On 12/4/2021 3:08 PM, Jarkko Sakkinen wrote: > > On Wed, Dec 01, 2021 at 11:23:08AM -0800, 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 two functions that can be used to modify the enclave page > > > permissions of regular enclave pages within an initialized enclave. > > > ENCLS[EMODPR] is run from the OS and used to restrict enclave page > > > permissions while ENCLU[EMODPE] is run from within the enclave to > > > extend enclave page permissions. > > > > > > Enclave page permission changes need to be approached with care and > > > for this reason this initial support is to allow enclave page > > > permission changes _only_ if the new permissions are the same or > > > more restrictive that the permissions originally vetted at the time the > > > pages were added to the enclave. Support for extending enclave page > > > permissions beyond what was originally vetted is deferred. > > > > This paragraph is out-of-scope for a commit message. You could have > > this in the cover letter but not here. I would just remove it. > > I think this is essential information that is mentioned in the cover > letter _and_ in this changelog. I will follow Dave's guidance and avoid > "deferred" by just removing that last sentence. > > > > > > Whether enclave page permissions are restricted or extended it > > > is necessary to ensure that the page table entries and enclave page > > > permissions are in sync. Introduce a new ioctl, SGX_IOC_PAGE_MODP, to > > > > SGX_IOC_PAGE_MODP does not match the naming convetion of these: > > > > * SGX_IOC_ENCLAVE_CREATE > > * SGX_IOC_ENCLAVE_ADD_PAGES > > * SGX_IOC_ENCLAVE_INIT > > ah - my understanding was that the SGX_IOC_ENCLAVE prefix related to > operations related to the entire enclave and thus I introduced the > prefix SGX_IOC_PAGE to relate to operations on pages within an enclave. SGX_IOC_ENCLAVE_ADD_PAGES is also operation working on pages within an enclave. Also, to be aligned with SGX_IOC_ENCLAVE_ADD_PAGES, the new operations should also take secinfo as input. > > > > > A better name would be SGX_IOC_ENCLAVE_MOD_PROTECTIONS. It doesn't > > do harm to be a more verbose. > > Will do. I see later you propose SGX_IOC_ENCLAVE_MODIFY_TYPE - would you > like them to be consistent wrt MOD/MODIFY? I would considering introducing just one new ioctl: SGX_IOC_ENCLAVE_MODIFY_PAGES and choose either operations based on e.g. a flag (see flags field SGX_IOC_ENCLAVE_ADD_PAGES). > Reinette /Jarkko
