Messages in this thread | | | Date | Fri, 14 Jan 2022 16:41:59 -0800 | Subject | Re: [PATCH 05/25] x86/sgx: Introduce runtime protection bits | From | Reinette Chatre <> |
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Hi Jarkko,
On 1/14/2022 4:27 PM, Jarkko Sakkinen wrote: > On Fri, Jan 14, 2022 at 04:01:33PM -0800, Reinette Chatre wrote: >> Hi Jarkko, >> >> On 1/14/2022 3:15 PM, Jarkko Sakkinen wrote: >>> On Fri, Jan 14, 2022 at 03:05:21PM -0800, Reinette Chatre wrote: >>>> Hi Jarkko, >>> >>> How enclave can check a page range that EPCM has the expected permissions? >> >> Only way to change EPCM permissions from outside enclave is to run ENCLS[EMODPR] >> that needs to be accepted from within the enclave via ENCLU[EACCEPT]. At that >> time the enclave provides the expected permissions and that will fail >> if there is a mismatch with the EPCM permissions (SGX_PAGE_ATTRIBUTES_MISMATCH). > > This is a very valid point but that does make the introspection possible > only at the time of EACCEPT. > > It does not give tools for enclave to make sure that EMODPR-ETRACK dance > was ever exercised.
Could you please elaborate? EACCEPT is available to the enclave as a tool and it would fail if ETRACK was not completed (error SGX_NOT_TRACKED).
Here is the relevant snippet from the SDM from the section where it describes EACCEPT:
IF (Tracking not correct) THEN RFLAGS.ZF := 1; RAX := SGX_NOT_TRACKED; GOTO DONE; FI;
Reinette
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