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

diff --git a/tools/testing/selftests/sgx/main.c b/tools/testing/selftests/sgx/main.c
index 3a82bae..2c69045 100644 (file)
--- a/tools/testing/selftests/sgx/main.c
+++ b/tools/testing/selftests/sgx/main.c
@@ -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