[PATCH V3 29/30] selftests/sgx: Test reclaiming of untouched page

Reinette Chatre
2022-04-04T21:27:11Z

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_TYPE 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@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
---
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 | 82 ++++++++++++++++++++++++++++++
1 file changed, 82 insertions(+)

diff --git a/tools/testing/selftests/sgx/main.c b/tools/testing/selftests/sgx/main.c
index f9f8e3697fa6..82cc2283be03 100644
--- a/tools/testing/selftests/sgx/main.c
+++ b/tools/testing/selftests/sgx/main.c
@@ -1807,4 +1807,86 @@ 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;
+ struct sgx_secinfo secinfo;
+ 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_TYPE, &modt_ioc);
+
+ if (ret == -1) {
+ if (errno == ENOTTY)
+ SKIP(return, "Kernel does not support SGX_IOC_ENCLAVE_MODIFY_TYPE 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));
+ memset(&secinfo, 0, sizeof(secinfo));
+
+ secinfo.flags = SGX_PAGE_TYPE_TRIM << 8;
+ modt_ioc.offset = encl_get_data_offset(&self->encl) + PAGE_SIZE;
+ modt_ioc.length = PAGE_SIZE;
+ modt_ioc.secinfo = (unsigned long)&secinfo;
+ ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_MODIFY_TYPE, &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