[PATCH V4 30/31] selftests/sgx: Test reclaiming of untouched page

[Reinette Chatre]

Removing a page from an initialized enclave involves three steps:
(1) the user requests changing the page type to PT_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().

Remove a page that has never been accessed. This means that when the
first ioctl() requesting page removal arrives, there will be no page
table entry, yet a valid page table entry needs to exist for the
ENCLU[EACCEPT] function to succeed. In this test it is verified that
a page table entry can still be installed for a page that is in the
process of being removed.

Suggested-by: Haitao Huang <haitao.huang@xxxxxxxxx>
Acked-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
---
Changes since V3:
- Add Jarkko's Acked-by tag.
- Rename SGX_IOC_ENCLAVE_MODIFY_TYPE to
  SGX_IOC_ENCLAVE_MODIFY_TYPES. (Jarkko)
- User provides just page type to SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl(),
  replacing secinfo. (Jarkko)
- Let the SKIP() call involving SGX_IOC_ENCLAVE_MODIFY_TYPES span
  two lines to address checkpatch.pl warning triggered by new longer
  name.

Changes since V2:
- Rename struct sgx_enclave_modt -> struct sgx_enclave_modify_type

Changes since V1:
- Update to support ioctl() name change (SGX_IOC_PAGE_MODT ->
  SGX_IOC_ENCLAVE_MODIFY_TYPE) and provide secinfo as parameter instead
  of just page type (Jarkko).
- Update test to reflect page removal ioctl() and struct name change:
  SGX_IOC_PAGE_REMOVE->SGX_IOC_ENCLAVE_REMOVE_PAGES,
  struct sgx_page_remove -> struct sgx_enclave_remove_pages (Jarkko).
- Ensure test is skipped when SGX2 not supported by kernel.

 tools/testing/selftests/sgx/main.c | 80 ++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)

diff --git a/tools/testing/selftests/sgx/main.c b/tools/testing/selftests/sgx/main.c
index ba1c6c4b5ff2..d49fce1a8df9 100644
--- a/tools/testing/selftests/sgx/main.c
+++ b/tools/testing/selftests/sgx/main.c
@@ -1790,4 +1790,84 @@ TEST_F(enclave, remove_added_page_invalid_access_after_eaccept)
 	EXPECT_EQ(self->run.exception_addr, data_start);
 }
 
+TEST_F(enclave, remove_untouched_page)
+{
+	struct sgx_enclave_remove_pages remove_ioc;
+	struct sgx_enclave_modify_type modt_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));
+
+	/*
+	 * Hardware (SGX2) and kernel support is needed for this test. Start
+	 * with check that test has a chance of succeeding.
+	 */
+	memset(&modt_ioc, 0, sizeof(modt_ioc));
+	ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_MODIFY_TYPES, &modt_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);
+
+	/* SGX2 is supported by kernel and hardware, test can proceed. */
+	memset(&self->run, 0, sizeof(self->run));
+	self->run.tcs = self->encl.encl_base;
+
+	data_start = self->encl.encl_base +
+			 encl_get_data_offset(&self->encl) + PAGE_SIZE;
+
+	memset(&modt_ioc, 0, sizeof(modt_ioc));
+
+	modt_ioc.offset = encl_get_data_offset(&self->encl) + PAGE_SIZE;
+	modt_ioc.length = PAGE_SIZE;
+	modt_ioc.page_type = SGX_PAGE_TYPE_TRIM;
+	ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_MODIFY_TYPES, &modt_ioc);
+	errno_save = ret == -1 ? errno : 0;
+
+	EXPECT_EQ(ret, 0);
+	EXPECT_EQ(errno_save, 0);
+	EXPECT_EQ(modt_ioc.result, 0);
+	EXPECT_EQ(modt_ioc.count, 4096);
+
+	/*
+	 * Enter enclave via TCS #1 and approve page removal by sending
+	 * EACCEPT for removed page.
+	 */
+
+	eaccept_op.epc_addr = data_start;
+	eaccept_op.flags = SGX_SECINFO_TRIM | SGX_SECINFO_MODIFIED;
+	eaccept_op.ret = 0;
+	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);
+
+	memset(&remove_ioc, 0, sizeof(remove_ioc));
+
+	remove_ioc.offset = encl_get_data_offset(&self->encl) + PAGE_SIZE;
+	remove_ioc.length = PAGE_SIZE;
+	ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_REMOVE_PAGES, &remove_ioc);
+	errno_save = ret == -1 ? errno : 0;
+
+	EXPECT_EQ(ret, 0);
+	EXPECT_EQ(errno_save, 0);
+	EXPECT_EQ(remove_ioc.count, 4096);
+}
+
 TEST_HARNESS_MAIN
-- 
2.25.1