linux.git/tools/testing/selftests/sgx, branch v5.17

selftests/sgx: Fix corrupted cpuid macro invocation

2021-12-17T16:52:33+00:00

The SGX selftest fails to build on tip/x86/sgx:

	main.c: In function ‘get_total_epc_mem’:
	main.c:296:17: error: implicit declaration of function ‘__cpuid’ [-Werror=implicit-function-declaration]
	  296 |                 __cpuid(&eax, &ebx, &ecx, &edx);
	      |                 ^~~~~~~

Include cpuid.h and use __cpuid_count() macro in order to fix the
compilation issue.

[ dhansen: tweak commit message ]

Fixes: f0ff2447b861 ("selftests/sgx: Add a new kselftest: Unclobbered_vdso_oversubscribed")
Signed-off-by: Jarkko Sakkinen 
Signed-off-by: Dave Hansen 
Acked-by: Reinette Chatre 
Link: https://lkml.kernel.org/r/20211204202355.23005-1-jarkko@kernel.org
Cc: Shuah Khan

selftests/sgx: Add test for multiple TCS entry

2021-11-15T19:34:16+00:00

Each thread executing in an enclave is associated with a Thread Control
Structure (TCS). The SGX test enclave contains two hardcoded TCS, thus
supporting two threads in the enclave.

Add a test to ensure it is possible to enter enclave at both entrypoints.

Signed-off-by: Reinette Chatre 
Signed-off-by: Dave Hansen 
Reviewed-by: Jarkko Sakkinen 
Acked-by: Dave Hansen 
Link: https://lkml.kernel.org/r/7be151a57b4c7959a2364753b995e0006efa3da1.1636997631.git.reinette.chatre@intel.com

selftests/sgx: Enable multiple thread support

2021-11-15T19:34:14+00:00

Each thread executing in an enclave is associated with a Thread Control
Structure (TCS). The test enclave contains two hardcoded TCS. Each TCS
contains meta-data used by the hardware to save and restore thread specific
information when entering/exiting the enclave.

The two TCS structures within the test enclave share their SSA (State Save
Area) resulting in the threads clobbering each other's data. Fix this by
providing each TCS their own SSA area.

Additionally, there is an 8K stack space and its address is
computed from the enclave entry point which is correctly done for
TCS #1 that starts on the first address inside the enclave but
results in out of bounds memory when entering as TCS #2. Split 8K
stack space into two separate pages with offset symbol between to ensure
the current enclave entry calculation can continue to be used for both
threads.

While using the enclave with multiple threads requires these fixes the
impact is not apparent because every test up to this point enters the
enclave from the first TCS.

More detail about the stack fix:
-------------------------------
Before this change the test enclave (test_encl) looks as follows:

.tcs (2 pages):
(page 1) TCS #1
(page 2) TCS #2

.text (1 page)
One page of code

.data (5 pages)
(page 1) encl_buffer
(page 2) encl_buffer
(page 3) SSA
(page 4 and 5) STACK
encl_stack:

As shown above there is a symbol, encl_stack, that points to the end of the
.data segment (pointing to the end of page 5 in .data) which is also the
end of the enclave.

The enclave entry code computes the stack address by adding encl_stack to
the pointer to the TCS that entered the enclave. When entering at TCS #1
the stack is computed correctly but when entering at TCS #2 the stack
pointer would point to one page beyond the end of the enclave and a #PF
would result when TCS #2 attempts to enter the enclave.

The fix involves moving the encl_stack symbol between the two stack pages.
Doing so enables the stack address computation in the entry code to compute
the correct stack address for each TCS.

Signed-off-by: Reinette Chatre 
Signed-off-by: Dave Hansen 
Reviewed-by: Jarkko Sakkinen 
Acked-by: Dave Hansen 
Link: https://lkml.kernel.org/r/a49dc0d85401db788a0a3f0d795e848abf3b1f44.1636997631.git.reinette.chatre@intel.com

selftests/sgx: Add page permission and exception test

2021-11-15T19:34:13+00:00

The Enclave Page Cache Map (EPCM) is a secure structure used by the
processor to track the contents of the enclave page cache. The EPCM
contains permissions with which enclave pages can be accessed. SGX
support allows EPCM and PTE page permissions to differ - as long as
the PTE permissions do not exceed the EPCM permissions.

Add a test that:
(1) Creates an SGX enclave page with writable EPCM permission.
(2) Changes the PTE permission on the page to read-only. This should
    be permitted because the permission does not exceed the EPCM
    permission.
(3) Attempts a write to the page. This should generate a page fault
    (#PF) because of the read-only PTE even though the EPCM
    permissions allow the page to be written to.

This introduces the first test of SGX exception handling. In this test
the issue that caused the exception (PTE page permissions) can be fixed
from outside the enclave and after doing so it is possible to re-enter
enclave at original entrypoint with ERESUME.

Signed-off-by: Reinette Chatre 
Signed-off-by: Dave Hansen 
Reviewed-by: Jarkko Sakkinen 
Acked-by: Dave Hansen 
Link: https://lkml.kernel.org/r/3bcc73a4b9fe8780bdb40571805e7ced59e01df7.1636997631.git.reinette.chatre@intel.com

selftests/sgx: Rename test properties in preparation for more enclave tests

2021-11-15T19:34:11+00:00

SGX selftests prepares a data structure outside of the enclave with
the type of and data for the operation that needs to be run within
the enclave. At this time only two complementary operations are supported
by the enclave: copying a value from outside the enclave into a default
buffer within the enclave and reading a value from the enclave's default
buffer into a variable accessible outside the enclave.

In preparation for more operations supported by the enclave the names of the
current enclave operations are changed to more accurately reflect the
operations and more easily distinguish it from future operations:

* The enums ENCL_OP_PUT and ENCL_OP_GET are renamed to ENCL_OP_PUT_TO_BUFFER
  and ENCL_OP_GET_FROM_BUFFER respectively.
* The structs encl_op_put and encl_op_get are renamed to encl_op_put_to_buf
  and encl_op_get_from_buf respectively.
* The enclave functions do_encl_op_put and do_encl_op_get are renamed to
  do_encl_op_put_to_buf and do_encl_op_get_from_buf respectively.

No functional changes.

Suggested-by: Jarkko Sakkinen 
Signed-off-by: Reinette Chatre 
Signed-off-by: Dave Hansen 
Acked-by: Jarkko Sakkinen 
Acked-by: Dave Hansen 
Link: https://lkml.kernel.org/r/023fda047c787cf330b88ed9337705edae6a0078.1636997631.git.reinette.chatre@intel.com

selftests/sgx: Provide per-op parameter structs for the test enclave

2021-11-15T19:34:10+00:00

To add more operations to the test enclave, the protocol needs to allow
to have operations with varying parameters. Create a separate parameter
struct for each existing operation, with the shared parameters in struct
encl_op_header.

[reinette: rebased to apply on top of oversubscription test series]
Signed-off-by: Jarkko Sakkinen 
Signed-off-by: Reinette Chatre 
Signed-off-by: Dave Hansen 
Acked-by: Dave Hansen 
Link: https://lkml.kernel.org/r/f9a4a8c436b538003b8ebddaa66083992053cef1.1636997631.git.reinette.chatre@intel.com

selftests/sgx: Add a new kselftest: Unclobbered_vdso_oversubscribed

2021-11-15T19:34:08+00:00

Add a variation of the unclobbered_vdso test.

In the new test, create a heap for the test enclave, which has the same
size as all available Enclave Page Cache (EPC) pages in the system. This
will guarantee that all test_encl.elf pages *and* SGX Enclave Control
Structure (SECS) have been swapped out by the page reclaimer during the
load time.

This test will trigger both the page reclaimer and the page fault handler.
The page reclaimer triggered, while the heap is being created during the
load time. The page fault handler is triggered for all the required pages,
while the test case is executing.

Signed-off-by: Jarkko Sakkinen 
Signed-off-by: Reinette Chatre 
Signed-off-by: Dave Hansen 
Acked-by: Dave Hansen 
Link: https://lkml.kernel.org/r/41f7c508eea79a3198b5014d7691903be08f9ff1.1636997631.git.reinette.chatre@intel.com

selftests/sgx: Move setup_test_encl() to each TEST_F()

2021-11-15T19:34:07+00:00

Create the test enclave inside each TEST_F(), instead of FIXTURE_SETUP(),
so that the heap size can be defined per test.

Signed-off-by: Jarkko Sakkinen 
Signed-off-by: Reinette Chatre 
Signed-off-by: Dave Hansen 
Acked-by: Dave Hansen 
Link: https://lkml.kernel.org/r/70ca264535d2ca0dc8dcaf2281e7d6965f8d4a24.1636997631.git.reinette.chatre@intel.com

selftests/sgx: Encpsulate the test enclave creation

2021-11-15T19:34:05+00:00

Introduce setup_test_encl() so that the enclave creation can be moved to
TEST_F()'s. This is required for a reclaimer test where the heap size needs
to be set large enough to triger the page reclaimer.

Signed-off-by: Jarkko Sakkinen 
Signed-off-by: Reinette Chatre 
Signed-off-by: Dave Hansen 
Acked-by: Dave Hansen 
Link: https://lkml.kernel.org/r/bee0ca867a95828a569c1ba2a8e443a44047dc71.1636997631.git.reinette.chatre@intel.com

selftests/sgx: Dump segments and /proc/self/maps only on failure

2021-11-15T19:34:04+00:00

Logging is always a compromise between clarity and detail. The main use
case for dumping VMA's is when FIXTURE_SETUP() fails, and is less important
for enclaves that do initialize correctly. Therefore, print the segments
and /proc/self/maps only in the error case.

Finally, if a single test ever creates multiple enclaves, the amount of
log lines would become enormous.

Signed-off-by: Jarkko Sakkinen 
Signed-off-by: Reinette Chatre 
Signed-off-by: Dave Hansen 
Acked-by: Dave Hansen 
Link: https://lkml.kernel.org/r/23cef0ae1de3a8a74cbfbbe74eca48ca3f300fde.1636997631.git.reinette.chatre@intel.com