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.
Acked-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V4: - Rename struct sgx_enclave_modify_type -> struct sgx_enclave_modify_types. (Jarkko)
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). - Use ioctl() instead of ioctl in text (Dave).
tools/testing/selftests/sgx/main.c | 114 +++++++++++++++++++++++++++++ 1 file changed, 114 insertions(+)
diff --git a/tools/testing/selftests/sgx/main.c b/tools/testing/selftests/sgx/main.c index 8bf43646e0bb..3a82bae915d1 100644 --- 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