Messages in this thread | | | Date | Mon, 6 Dec 2021 13:42:08 -0800 | Subject | Re: [PATCH 10/25] x86/sgx: Support enclave page permission changes | From | Reinette Chatre <> |
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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.
> > 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?
Reinette
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