selftests/sgx: Test faulty enclave behavior

Removing a page from an initialized enclave involves three steps:
first the user requests changing the page type to SGX_PAGE_TYPE_TRIM
via an ioctl(), on success the ENCLU[EACCEPT] instruction needs to be
run from within the enclave to accept the page removal, finally the
user requests page removal to be completed via an ioctl(). Only after
acceptance (ENCLU[EACCEPT]) from within the enclave can the kernel
remove the page from a running enclave.

Test the behavior when the user's request to change the page type
succeeds, but the ENCLU[EACCEPT] instruction is not run before the
ioctl() requesting page removal is run. This should not be permitted.

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/fa5da30ebac108b7517194c3038b52995602b996.1652137848.git.reinette.chatre@intel.com

diff --git a/tools/testing/selftests/sgx/main.c b/tools/testing/selftests/sgx/main.c
index 8bf43646e0bba687f363ff877c5f327876496137..3a82bae915d18b4837f53fc830ccea3c35ea25d8 100644 (file)
--- a/tools/testing/selftests/sgx/main.c
+++ b/tools/testing/selftests/sgx/main.c
@@ -1433,4 +1433,118 @@ TEST_F(enclave, tcs_create)
        munmap(addr, 3 * PAGE_SIZE);
 }
 
+/*
+ * Ensure sane behavior if user requests page removal, does not run
+ * EACCEPT from within enclave but still attempts to finalize page removal
+ * with the SGX_IOC_ENCLAVE_REMOVE_PAGES ioctl(). The latter should fail
+ * because the removal was not EACCEPTed from within the enclave.
+ */
+TEST_F(enclave, remove_added_page_no_eaccept)
+{
+       struct sgx_enclave_remove_pages remove_ioc;
+       struct encl_op_get_from_addr get_addr_op;
+       struct sgx_enclave_modify_types modt_ioc;
+       struct encl_op_put_to_addr put_addr_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(&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);
+
+       /*
+        * 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(&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);
+
+       /* Skip EACCEPT */
+
+       /* Send final ioctl() to complete page removal */
+       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;
+
+       /* Operation not permitted since EACCEPT was omitted. */
+       EXPECT_EQ(ret, -1);
+       EXPECT_EQ(errno_save, EPERM);
+       EXPECT_EQ(remove_ioc.count, 0);
+}
+
 TEST_HARNESS_MAIN