From: Reinette Chatre reinette.chatre@intel.com
Kernel should not allow permission changes on TCS pages. Add test to confirm this behavior.
Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- tools/testing/selftests/sgx/main.c | 74 ++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+)
diff --git a/tools/testing/selftests/sgx/main.c b/tools/testing/selftests/sgx/main.c index aec3355d2ace..ea5f2e064687 100644 --- a/tools/testing/selftests/sgx/main.c +++ b/tools/testing/selftests/sgx/main.c @@ -121,6 +121,24 @@ static Elf64_Sym *vdso_symtab_get(struct vdso_symtab *symtab, const char *name) return NULL; }
+/* + * Return the offset in the enclave where the TCS segment can be found. + * The first RW segment loaded is the TCS. + */ +static off_t encl_get_tcs_offset(struct encl *encl) +{ + int i; + + for (i = 0; i < encl->nr_segments; i++) { + struct encl_segment *seg = &encl->segment_tbl[i]; + + if (i == 0 && seg->prot == (PROT_READ | PROT_WRITE)) + return seg->offset; + } + + return -1; +} + /* * Return the offset in the enclave where the data segment can be found. * The first RW segment loaded is the TCS, skip that to get info on the @@ -567,6 +585,62 @@ TEST_F(enclave, pte_permissions) EXPECT_EQ(self->run.exception_addr, 0); }
+/* + * Modifying permissions of TCS page should not be possible. + */ +TEST_F(enclave, tcs_permissions) +{ + struct sgx_enclave_restrict_perm ioc; + struct sgx_secinfo secinfo; + 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; + + memset(&ioc, 0, sizeof(ioc)); + memset(&secinfo, 0, sizeof(secinfo)); + + /* + * Ensure kernel supports needed ioctl() and system supports needed + * commands. + */ + + ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS, &ioc); + errno_save = ret == -1 ? errno : 0; + + /* + * Invalid parameters were provided during sanity check, + * expect command to fail. + */ + ASSERT_EQ(ret, -1); + + /* ret == -1 */ + if (errno_save == ENOTTY) + SKIP(return, + "Kernel does not support SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS ioctl()"); + else if (errno_save == ENODEV) + SKIP(return, "System does not support SGX2"); + + /* + * Attempt to make TCS page read-only. This is not allowed and + * should be prevented by the kernel. + */ + secinfo.flags = PROT_READ; + ioc.offset = encl_get_tcs_offset(&self->encl); + ioc.length = PAGE_SIZE; + ioc.secinfo = (unsigned long)&secinfo; + + ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS, &ioc); + errno_save = ret == -1 ? errno : 0; + + EXPECT_EQ(ret, -1); + EXPECT_EQ(errno_save, EINVAL); + EXPECT_EQ(ioc.result, 0); + EXPECT_EQ(ioc.count, 0); +} + /* * Enclave page permission test. *