selftests/sgx: Test invalid access to removed enclave page
Removing a page from an initialized enclave involves three steps:
(1) the user requests changing the page type to SGX_PAGE_TYPE_TRIM
via the SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl(), (2) on success the
ENCLU[EACCEPT] instruction is run from within the enclave to accept
the page removal, (3) the user initiates the actual removal of the
page via the SGX_IOC_ENCLAVE_REMOVE_PAGES ioctl().
Test two possible invalid accesses during the page removal flow:
* Test the behavior when a request to remove the page by changing its
type to SGX_PAGE_TYPE_TRIM completes successfully but instead of
executing ENCLU[EACCEPT] from within the enclave the enclave attempts
to read from the page. Even though the page is accessible from the
page table entries its type is SGX_PAGE_TYPE_TRIM and thus not
accessible according to SGX. The expected behavior is a page fault
with the SGX flag set in the error code.
* Test the behavior when the page type is changed successfully and
ENCLU[EACCEPT] was run from within the enclave. The final ioctl(),
SGX_IOC_ENCLAVE_REMOVE_PAGES, is omitted and replaced with an
attempt to access the page. Even though the page is accessible
from the page table entries its type is SGX_PAGE_TYPE_TRIM and
thus not accessible according to SGX. The expected behavior is
a page fault with the SGX flag set in the error code.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/189a86c25d6d62da7cfdd08ee97abc1a06fcc179.1652137848.git.reinette.chatre@intel.com