Commit 35c7e6da authored by Reinette Chatre's avatar Reinette Chatre Committed by Dave Hansen
Browse files

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: default avatarReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Acked-by: default avatarJarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/189a86c25d6d62da7cfdd08ee97abc1a06fcc179.1652137848.git.reinette.chatre@intel.com
parent 50b822e4

tools/testing/selftests/sgx/main.c

+243 −0
Original line number Diff line number Diff line
@@ -1547,4 +1547,247 @@ TEST_F(enclave, remove_added_page_no_eaccept) 
	EXPECT_EQ(remove_ioc.count, 0);

}



/*

 * Request enclave page removal but instead of correctly following with

 * EACCEPT a read attempt to page is made from within the enclave.

 */

TEST_F(enclave, remove_added_page_invalid_access)

{

	struct encl_op_get_from_addr get_addr_op;

	struct encl_op_put_to_addr put_addr_op;

	struct sgx_enclave_modify_types ioc;

	unsigned long data_start;

	int ret, errno_save;



	ASSERT_TRUE(setup_test_encl(ENCL_HEAP_SIZE_DEFAULT, &self->encl, _metadata));



	memset(&self->run, 0, sizeof(self->run));

	self->run.tcs = self->encl.encl_base;



	/*

	 * Hardware (SGX2) and kernel support is needed for this test. Start

	 * with check that test has a chance of succeeding.

	 */

	memset(&ioc, 0, sizeof(ioc));

	ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_MODIFY_TYPES, &ioc);



	if (ret == -1) {

		if (errno == ENOTTY)

			SKIP(return,

			     "Kernel does not support SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl()");

		else if (errno == ENODEV)

			SKIP(return, "System does not support SGX2");

	}



	/*

	 * Invalid parameters were provided during sanity check,

	 * expect command to fail.

	 */

	EXPECT_EQ(ret, -1);



	/*

	 * Page that will be removed is the second data page in the .data

	 * segment. This forms part of the local encl_buffer within the

	 * enclave.

	 */

	data_start = self->encl.encl_base +

		     encl_get_data_offset(&self->encl) + PAGE_SIZE;



	/*

	 * Sanity check that page at @data_start is writable before

	 * removing it.

	 *

	 * Start by writing MAGIC to test page.

	 */

	put_addr_op.value = MAGIC;

	put_addr_op.addr = data_start;

	put_addr_op.header.type = ENCL_OP_PUT_TO_ADDRESS;



	EXPECT_EQ(ENCL_CALL(&put_addr_op, &self->run, true), 0);



	EXPECT_EEXIT(&self->run);

	EXPECT_EQ(self->run.exception_vector, 0);

	EXPECT_EQ(self->run.exception_error_code, 0);

	EXPECT_EQ(self->run.exception_addr, 0);



	/*

	 * Read memory that was just written to, confirming that data

	 * previously written (MAGIC) is present.

	 */

	get_addr_op.value = 0;

	get_addr_op.addr = data_start;

	get_addr_op.header.type = ENCL_OP_GET_FROM_ADDRESS;



	EXPECT_EQ(ENCL_CALL(&get_addr_op, &self->run, true), 0);



	EXPECT_EQ(get_addr_op.value, MAGIC);

	EXPECT_EEXIT(&self->run);

	EXPECT_EQ(self->run.exception_vector, 0);

	EXPECT_EQ(self->run.exception_error_code, 0);

	EXPECT_EQ(self->run.exception_addr, 0);



	/* Start page removal by requesting change of page type to PT_TRIM. */

	memset(&ioc, 0, sizeof(ioc));



	ioc.offset = encl_get_data_offset(&self->encl) + PAGE_SIZE;

	ioc.length = PAGE_SIZE;

	ioc.page_type = SGX_PAGE_TYPE_TRIM;



	ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_MODIFY_TYPES, &ioc);

	errno_save = ret == -1 ? errno : 0;



	EXPECT_EQ(ret, 0);

	EXPECT_EQ(errno_save, 0);

	EXPECT_EQ(ioc.result, 0);

	EXPECT_EQ(ioc.count, 4096);



	/*

	 * Read from page that was just removed.

	 */

	get_addr_op.value = 0;



	EXPECT_EQ(ENCL_CALL(&get_addr_op, &self->run, true), 0);



	/*

	 * From kernel perspective the page is present but according to SGX the

	 * page should not be accessible so a #PF with SGX bit set is

	 * expected.

	 */



	EXPECT_EQ(self->run.function, ERESUME);

	EXPECT_EQ(self->run.exception_vector, 14);

	EXPECT_EQ(self->run.exception_error_code, 0x8005);

	EXPECT_EQ(self->run.exception_addr, data_start);

}



/*

 * Request enclave page removal and correctly follow with

 * EACCEPT but do not follow with removal ioctl() but instead a read attempt

 * to removed page is made from within the enclave.

 */

TEST_F(enclave, remove_added_page_invalid_access_after_eaccept)

{

	struct encl_op_get_from_addr get_addr_op;

	struct encl_op_put_to_addr put_addr_op;

	struct sgx_enclave_modify_types ioc;

	struct encl_op_eaccept eaccept_op;

	unsigned long data_start;

	int ret, errno_save;



	ASSERT_TRUE(setup_test_encl(ENCL_HEAP_SIZE_DEFAULT, &self->encl, _metadata));



	memset(&self->run, 0, sizeof(self->run));

	self->run.tcs = self->encl.encl_base;



	/*

	 * Hardware (SGX2) and kernel support is needed for this test. Start

	 * with check that test has a chance of succeeding.

	 */

	memset(&ioc, 0, sizeof(ioc));

	ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_MODIFY_TYPES, &ioc);



	if (ret == -1) {

		if (errno == ENOTTY)

			SKIP(return,

			     "Kernel does not support SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl()");

		else if (errno == ENODEV)

			SKIP(return, "System does not support SGX2");

	}



	/*

	 * Invalid parameters were provided during sanity check,

	 * expect command to fail.

	 */

	EXPECT_EQ(ret, -1);



	/*

	 * Page that will be removed is the second data page in the .data

	 * segment. This forms part of the local encl_buffer within the

	 * enclave.

	 */

	data_start = self->encl.encl_base +

		     encl_get_data_offset(&self->encl) + PAGE_SIZE;



	/*

	 * Sanity check that page at @data_start is writable before

	 * removing it.

	 *

	 * Start by writing MAGIC to test page.

	 */

	put_addr_op.value = MAGIC;

	put_addr_op.addr = data_start;

	put_addr_op.header.type = ENCL_OP_PUT_TO_ADDRESS;



	EXPECT_EQ(ENCL_CALL(&put_addr_op, &self->run, true), 0);



	EXPECT_EEXIT(&self->run);

	EXPECT_EQ(self->run.exception_vector, 0);

	EXPECT_EQ(self->run.exception_error_code, 0);

	EXPECT_EQ(self->run.exception_addr, 0);



	/*

	 * Read memory that was just written to, confirming that data

	 * previously written (MAGIC) is present.

	 */

	get_addr_op.value = 0;

	get_addr_op.addr = data_start;

	get_addr_op.header.type = ENCL_OP_GET_FROM_ADDRESS;



	EXPECT_EQ(ENCL_CALL(&get_addr_op, &self->run, true), 0);



	EXPECT_EQ(get_addr_op.value, MAGIC);

	EXPECT_EEXIT(&self->run);

	EXPECT_EQ(self->run.exception_vector, 0);

	EXPECT_EQ(self->run.exception_error_code, 0);

	EXPECT_EQ(self->run.exception_addr, 0);



	/* Start page removal by requesting change of page type to PT_TRIM. */

	memset(&ioc, 0, sizeof(ioc));



	ioc.offset = encl_get_data_offset(&self->encl) + PAGE_SIZE;

	ioc.length = PAGE_SIZE;

	ioc.page_type = SGX_PAGE_TYPE_TRIM;



	ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_MODIFY_TYPES, &ioc);

	errno_save = ret == -1 ? errno : 0;



	EXPECT_EQ(ret, 0);

	EXPECT_EQ(errno_save, 0);

	EXPECT_EQ(ioc.result, 0);

	EXPECT_EQ(ioc.count, 4096);



	eaccept_op.epc_addr = (unsigned long)data_start;

	eaccept_op.ret = 0;

	eaccept_op.flags = SGX_SECINFO_TRIM | SGX_SECINFO_MODIFIED;

	eaccept_op.header.type = ENCL_OP_EACCEPT;



	EXPECT_EQ(ENCL_CALL(&eaccept_op, &self->run, true), 0);



	EXPECT_EEXIT(&self->run);

	EXPECT_EQ(self->run.exception_vector, 0);

	EXPECT_EQ(self->run.exception_error_code, 0);

	EXPECT_EQ(self->run.exception_addr, 0);

	EXPECT_EQ(eaccept_op.ret, 0);



	/* Skip ioctl() to remove page. */



	/*

	 * Read from page that was just removed.

	 */

	get_addr_op.value = 0;



	EXPECT_EQ(ENCL_CALL(&get_addr_op, &self->run, true), 0);



	/*

	 * From kernel perspective the page is present but according to SGX the

	 * page should not be accessible so a #PF with SGX bit set is

	 * expected.

	 */



	EXPECT_EQ(self->run.function, ERESUME);

	EXPECT_EQ(self->run.exception_vector, 14);

	EXPECT_EQ(self->run.exception_error_code, 0x8005);

	EXPECT_EQ(self->run.exception_addr, data_start);

}



TEST_HARNESS_MAIN