[PATCH v3 6/7] lib: stackinit: Convert to KUnit

Kees Cook
2022-02-27T18:45:16Z

Convert stackinit unit tests to KUnit, for better integration
into the kernel self test framework. Includes a rename of
test_stackinit.c to stackinit_kunit.c, and CONFIG_TEST_STACKINIT to
CONFIG_STACKINIT_KUNIT_TEST.

Adjust expected test results based on which stack initialization method
was chosen:

$ CMD="./tools/testing/kunit/kunit.py run stackinit --raw_output \
--arch=x86_64 --kconfig_add"

$ $CMD | grep stackinit:
# stackinit: pass:36 fail:0 skip:29 total:65

$ $CMD CONFIG_GCC_PLUGIN_STRUCTLEAK_USER=y | grep stackinit:
# stackinit: pass:37 fail:0 skip:28 total:65

$ $CMD CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF=y | grep stackinit:
# stackinit: pass:55 fail:0 skip:10 total:65

$ $CMD CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL=y | grep stackinit:
# stackinit: pass:62 fail:0 skip:3 total:65

$ $CMD CONFIG_INIT_STACK_ALL_PATTERN=y --make_option LLVM=1 | grep stackinit:
# stackinit: pass:60 fail:0 skip:5 total:65

$ $CMD CONFIG_INIT_STACK_ALL_ZERO=y --make_option LLVM=1 | grep stackinit:
# stackinit: pass:60 fail:0 skip:5 total:65

Temporarily remove the userspace-build mode, which will be restored in a
later patch.

Expand the size of the pre-case switch variable so it doesn't get
accidentally cleared.

Cc: David Gow <davidgow@google.com>
Cc: Daniel Latypov <dlatypov@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
v1: https://lore.kernel.org/lkml/20220224055145.1853657-1-keescook@chromium.org
v2:
- split "userspace KUnit stub" into separate header and patch (Daniel)
- Improve commit log and comments (David)
- Provide mapping of expected XFAIL tests to CONFIGs (David)
---
lib/Kconfig.debug | 22 +-
lib/Makefile | 4 +-
lib/{test_stackinit.c => stackinit_kunit.c} | 269 ++++++++------------
3 files changed, 121 insertions(+), 174 deletions(-)
rename lib/{test_stackinit.c => stackinit_kunit.c} (66%)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 14d90d03bc8d..a5556ab05240 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2511,6 +2511,17 @@ config OVERFLOW_KUNIT_TEST

If unsure, say N.

+config STACKINIT_KUNIT_TEST
+ tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
+ depends on KUNIT
+ default KUNIT_ALL_TESTS
+ help
+ Test if the kernel is zero-initializing stack variables and
+ padding. Coverage is controlled by compiler flags,
+ CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
+ CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
+ or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
+
config TEST_UDELAY
tristate "udelay test driver"
help
@@ -2602,17 +2613,6 @@ config TEST_OBJAGG
Enable this option to test object aggregation manager on boot
(or module load).

-
-config TEST_STACKINIT
- tristate "Test level of stack variable initialization"
- help
- Test if the kernel is zero-initializing stack variables and
- padding. Coverage is controlled by compiler flags,
- CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
- or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
-
- If unsure, say N.
-
config TEST_MEMINIT
tristate "Test heap/page initialization"
help
diff --git a/lib/Makefile b/lib/Makefile
index fdfcbfaff32f..353bc09ce38d 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -93,8 +93,6 @@ obj-$(CONFIG_TEST_KMOD) += test_kmod.o
obj-$(CONFIG_TEST_DEBUG_VIRTUAL) += test_debug_virtual.o
obj-$(CONFIG_TEST_MEMCAT_P) += test_memcat_p.o
obj-$(CONFIG_TEST_OBJAGG) += test_objagg.o
-CFLAGS_test_stackinit.o += $(call cc-disable-warning, switch-unreachable)
-obj-$(CONFIG_TEST_STACKINIT) += test_stackinit.o
obj-$(CONFIG_TEST_BLACKHOLE_DEV) += test_blackhole_dev.o
obj-$(CONFIG_TEST_MEMINIT) += test_meminit.o
obj-$(CONFIG_TEST_LOCKUP) += test_lockup.o
@@ -363,6 +361,8 @@ obj-$(CONFIG_CMDLINE_KUNIT_TEST) += cmdline_kunit.o
obj-$(CONFIG_SLUB_KUNIT_TEST) += slub_kunit.o
obj-$(CONFIG_MEMCPY_KUNIT_TEST) += memcpy_kunit.o
obj-$(CONFIG_OVERFLOW_KUNIT_TEST) += overflow_kunit.o
+CFLAGS_stackinit_kunit.o += $(call cc-disable-warning, switch-unreachable)
+obj-$(CONFIG_STACKINIT_KUNIT_TEST) += stackinit_kunit.o

obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o

diff --git a/lib/test_stackinit.c b/lib/stackinit_kunit.c
similarity index 66%
rename from lib/test_stackinit.c
rename to lib/stackinit_kunit.c
index a3c74e6a21ff..35c69aa425b2 100644
--- a/lib/test_stackinit.c
+++ b/lib/stackinit_kunit.c
@@ -2,76 +2,21 @@
/*
* Test cases for compiler-based stack variable zeroing via
* -ftrivial-auto-var-init={zero,pattern} or CONFIG_GCC_PLUGIN_STRUCTLEAK*.
+ * For example, see:
+ * https://www.kernel.org/doc/html/latest/dev-tools/kunit/kunit-tool.html#configuring-building-and-running-tests
+ * ./tools/testing/kunit/kunit.py run stackinit [--raw_output] \
+ * --make_option LLVM=1 \
+ * --kconfig_add CONFIG_INIT_STACK_ALL_ZERO=y
*
- * External build example:
- * clang -O2 -Wall -ftrivial-auto-var-init=pattern \
- * -o test_stackinit test_stackinit.c
*/
-#ifdef __KERNEL__
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

+#include <kunit/test.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>

-#else
-
-/* Userspace headers. */
-#include <stdio.h>
-#include <stdint.h>
-#include <string.h>
-#include <stdbool.h>
-#include <errno.h>
-#include <sys/types.h>
-
-/* Linux kernel-ism stubs for stand-alone userspace build. */
-#define KBUILD_MODNAME "stackinit"
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-#define pr_err(fmt, ...) fprintf(stderr, pr_fmt(fmt), ##__VA_ARGS__)
-#define pr_warn(fmt, ...) fprintf(stderr, pr_fmt(fmt), ##__VA_ARGS__)
-#define pr_info(fmt, ...) fprintf(stdout, pr_fmt(fmt), ##__VA_ARGS__)
-#define __init /**/
-#define __exit /**/
-#define __user /**/
-#define noinline __attribute__((__noinline__))
-#define __aligned(x) __attribute__((__aligned__(x)))
-#ifdef __clang__
-# define __compiletime_error(message) /**/
-#else
-# define __compiletime_error(message) __attribute__((__error__(message)))
-#endif
-#define __compiletime_assert(condition, msg, prefix, suffix) \
- do { \
- extern void prefix ## suffix(void) __compiletime_error(msg); \
- if (!(condition)) \
- prefix ## suffix(); \
- } while (0)
-#define _compiletime_assert(condition, msg, prefix, suffix) \
- __compiletime_assert(condition, msg, prefix, suffix)
-#define compiletime_assert(condition, msg) \
- _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
-#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
-#define BUILD_BUG_ON(condition) \
- BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
-typedef uint8_t u8;
-typedef uint16_t u16;
-typedef uint32_t u32;
-typedef uint64_t u64;
-
-#define module_init(func) static int (*do_init)(void) = func
-#define module_exit(func) static void (*do_exit)(void) = func
-#define MODULE_LICENSE(str) int main(void) { \
- int rc; \
- /* License: str */ \
- rc = do_init(); \
- if (rc == 0) \
- do_exit(); \
- return rc; \
- }
-
-#endif /* __KERNEL__ */
-
/* Exfiltration buffer. */
#define MAX_VAR_SIZE 128
static u8 check_buf[MAX_VAR_SIZE];
@@ -201,7 +146,7 @@ static bool range_contains(char *haystack_start, size_t haystack_size,
*/
#define DEFINE_TEST_DRIVER(name, var_type, which, xfail) \
/* Returns 0 on success, 1 on failure. */ \
-static noinline __init int test_ ## name (void) \
+static noinline void test_ ## name (struct kunit *test) \
{ \
var_type zero INIT_CLONE_ ## which; \
int ignored; \
@@ -220,10 +165,8 @@ static noinline __init int test_ ## name (void) \
/* Verify all bytes overwritten with 0xFF. */ \
for (sum = 0, i = 0; i < target_size; i++) \
sum += (check_buf[i] != 0xFF); \
- if (sum) { \
- pr_err(#name ": leaf fill was not 0xFF!?\n"); \
- return 1; \
- } \
+ KUNIT_ASSERT_EQ_MSG(test, sum, 0, \
+ "leaf fill was not 0xFF!?\n"); \
/* Clear entire check buffer for later bit tests. */ \
memset(check_buf, 0x00, sizeof(check_buf)); \
/* Extract stack-defined variable contents. */ \
@@ -231,32 +174,29 @@ static noinline __init int test_ ## name (void) \
FETCH_ARG_ ## which(zero)); \
\
/* Validate that compiler lined up fill and target. */ \
- if (!range_contains(fill_start, fill_size, \
- target_start, target_size)) { \
- pr_err(#name ": stack fill missed target!?\n"); \
- pr_err(#name ": fill %zu wide\n", fill_size); \
- pr_err(#name ": target offset by %d\n", \
- (int)((ssize_t)(uintptr_t)fill_start - \
- (ssize_t)(uintptr_t)target_start)); \
- return 1; \
- } \
+ KUNIT_ASSERT_TRUE_MSG(test, \
+ range_contains(fill_start, fill_size, \
+ target_start, target_size), \
+ "stack fill missed target!? " \
+ "(fill %zu wide, target offset by %d)\n", \
+ fill_size, \
+ (int)((ssize_t)(uintptr_t)fill_start - \
+ (ssize_t)(uintptr_t)target_start)); \
\
/* Look for any bytes still 0xFF in check region. */ \
for (sum = 0, i = 0; i < target_size; i++) \
sum += (check_buf[i] == 0xFF); \
\
- if (sum == 0) { \
- pr_info(#name " ok\n"); \
- return 0; \
- } else { \
- pr_warn(#name " %sFAIL (uninit bytes: %d)\n", \
- (xfail) ? "X" : "", sum); \
- return (xfail) ? 0 : 1; \
- } \
+ if (sum != 0 && xfail) \
+ kunit_skip(test, \
+ "XFAIL uninit bytes: %d\n", \
+ sum); \
+ KUNIT_ASSERT_EQ_MSG(test, sum, 0, \
+ "uninit bytes: %d\n", sum); \
}
#define DEFINE_TEST(name, var_type, which, init_level, xfail) \
/* no-op to force compiler into ignoring "uninitialized" vars */\
-static noinline __init DO_NOTHING_TYPE_ ## which(var_type) \
+static noinline DO_NOTHING_TYPE_ ## which(var_type) \
do_nothing_ ## name(var_type *ptr) \
{ \
/* Will always be true, but compiler doesn't know. */ \
@@ -265,9 +205,8 @@ do_nothing_ ## name(var_type *ptr) \
else \
return DO_NOTHING_RETURN_ ## which(ptr + 1); \
} \
-static noinline __init int leaf_ ## name(unsigned long sp, \
- bool fill, \
- var_type *arg) \
+static noinline int leaf_ ## name(unsigned long sp, bool fill, \
+ var_type *arg) \
{ \
char buf[VAR_BUFFER]; \
var_type var \
@@ -341,6 +280,27 @@ struct test_user {
unsigned long four;
};

+#define ALWAYS_PASS WANT_SUCCESS
+#define ALWAYS_FAIL XFAIL
+
+#ifdef CONFIG_INIT_STACK_NONE
+# define USER_PASS XFAIL
+# define BYREF_PASS XFAIL
+# define STRONG_PASS XFAIL
+#elif defined(CONFIG_GCC_PLUGIN_STRUCTLEAK_USER)
+# define USER_PASS WANT_SUCCESS
+# define BYREF_PASS XFAIL
+# define STRONG_PASS XFAIL
+#elif defined(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF)
+# define USER_PASS WANT_SUCCESS
+# define BYREF_PASS WANT_SUCCESS
+# define STRONG_PASS XFAIL
+#else
+# define USER_PASS WANT_SUCCESS
+# define BYREF_PASS WANT_SUCCESS
+# define STRONG_PASS WANT_SUCCESS
+#endif
+
#define DEFINE_SCALAR_TEST(name, init, xfail) \
DEFINE_TEST(name ## _ ## init, name, SCALAR, \
init, xfail)
@@ -364,27 +324,26 @@ struct test_user {
DEFINE_STRUCT_TEST(trailing_hole, init, xfail); \
DEFINE_STRUCT_TEST(packed, init, xfail)

-#define DEFINE_STRUCT_INITIALIZER_TESTS(base) \
+#define DEFINE_STRUCT_INITIALIZER_TESTS(base, xfail) \
DEFINE_STRUCT_TESTS(base ## _ ## partial, \
- WANT_SUCCESS); \
- DEFINE_STRUCT_TESTS(base ## _ ## all, \
- WANT_SUCCESS)
+ xfail); \
+ DEFINE_STRUCT_TESTS(base ## _ ## all, xfail)

/* These should be fully initialized all the time! */
-DEFINE_SCALAR_TESTS(zero, WANT_SUCCESS);
-DEFINE_STRUCT_TESTS(zero, WANT_SUCCESS);
+DEFINE_SCALAR_TESTS(zero, ALWAYS_PASS);
+DEFINE_STRUCT_TESTS(zero, ALWAYS_PASS);
/* Struct initializers: padding may be left uninitialized. */
-DEFINE_STRUCT_INITIALIZER_TESTS(static);
-DEFINE_STRUCT_INITIALIZER_TESTS(dynamic);
-DEFINE_STRUCT_INITIALIZER_TESTS(runtime);
-DEFINE_STRUCT_INITIALIZER_TESTS(assigned_static);
-DEFINE_STRUCT_INITIALIZER_TESTS(assigned_dynamic);
-DEFINE_STRUCT_TESTS(assigned_copy, XFAIL);
+DEFINE_STRUCT_INITIALIZER_TESTS(static, STRONG_PASS);
+DEFINE_STRUCT_INITIALIZER_TESTS(dynamic, STRONG_PASS);
+DEFINE_STRUCT_INITIALIZER_TESTS(runtime, STRONG_PASS);
+DEFINE_STRUCT_INITIALIZER_TESTS(assigned_static, STRONG_PASS);
+DEFINE_STRUCT_INITIALIZER_TESTS(assigned_dynamic, STRONG_PASS);
+DEFINE_STRUCT_TESTS(assigned_copy, ALWAYS_FAIL);
/* No initialization without compiler instrumentation. */
-DEFINE_SCALAR_TESTS(none, WANT_SUCCESS);
-DEFINE_STRUCT_TESTS(none, WANT_SUCCESS);
+DEFINE_SCALAR_TESTS(none, STRONG_PASS);
+DEFINE_STRUCT_TESTS(none, BYREF_PASS);
/* Initialization of members with __user attribute. */
-DEFINE_TEST(user, struct test_user, STRUCT, none, WANT_SUCCESS);
+DEFINE_TEST(user, struct test_user, STRUCT, none, USER_PASS);

/*
* Check two uses through a variable declaration outside either path,
@@ -398,7 +357,7 @@ static int noinline __leaf_switch_none(int path, bool fill)
* This is intentionally unreachable. To silence the
* warning, build with -Wno-switch-unreachable
*/
- uint64_t var;
+ uint64_t var[10];

case 1:
target_start = &var;
@@ -423,19 +382,19 @@ static int noinline __leaf_switch_none(int path, bool fill)
memcpy(check_buf, target_start, target_size);
break;
default:
- var = 5;
- return var & forced_mask;
+ var[1] = 5;
+ return var[1] & forced_mask;
}
return 0;
}

-static noinline __init int leaf_switch_1_none(unsigned long sp, bool fill,
+static noinline int leaf_switch_1_none(unsigned long sp, bool fill,
uint64_t *arg)
{
return __leaf_switch_none(1, fill);
}

-static noinline __init int leaf_switch_2_none(unsigned long sp, bool fill,
+static noinline int leaf_switch_2_none(unsigned long sp, bool fill,
uint64_t *arg)
{
return __leaf_switch_none(2, fill);
@@ -447,68 +406,56 @@ static noinline __init int leaf_switch_2_none(unsigned long sp, bool fill,
* non-code areas (i.e. in a switch statement before the first "case").
* https://bugs.llvm.org/show_bug.cgi?id=44916
*/
-DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, XFAIL);
-DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, XFAIL);
-
-static int __init test_stackinit_init(void)
-{
- unsigned int failures = 0;
-
-#define test_scalars(init) do { \
- failures += test_u8_ ## init (); \
- failures += test_u16_ ## init (); \
- failures += test_u32_ ## init (); \
- failures += test_u64_ ## init (); \
- failures += test_char_array_ ## init (); \
- } while (0)
-
-#define test_structs(init) do { \
- failures += test_small_hole_ ## init (); \
- failures += test_big_hole_ ## init (); \
- failures += test_trailing_hole_ ## init (); \
- failures += test_packed_ ## init (); \
- } while (0)
-
+DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, ALWAYS_FAIL);
+DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, ALWAYS_FAIL);
+
+#define KUNIT_test_scalars(init) \
+ KUNIT_CASE(test_u8_ ## init), \
+ KUNIT_CASE(test_u16_ ## init), \
+ KUNIT_CASE(test_u32_ ## init), \
+ KUNIT_CASE(test_u64_ ## init), \
+ KUNIT_CASE(test_char_array_ ## init)
+
+#define KUNIT_test_structs(init) \
+ KUNIT_CASE(test_small_hole_ ## init), \
+ KUNIT_CASE(test_big_hole_ ## init), \
+ KUNIT_CASE(test_trailing_hole_ ## init),\
+ KUNIT_CASE(test_packed_ ## init) \
+
+static struct kunit_case stackinit_test_cases[] = {
/* These are explicitly initialized and should always pass. */
- test_scalars(zero);
- test_structs(zero);
+ KUNIT_test_scalars(zero),
+ KUNIT_test_structs(zero),
/* Padding here appears to be accidentally always initialized? */
- test_structs(dynamic_partial);
- test_structs(assigned_dynamic_partial);
+ KUNIT_test_structs(dynamic_partial),
+ KUNIT_test_structs(assigned_dynamic_partial),
/* Padding initialization depends on compiler behaviors. */
- test_structs(static_partial);
- test_structs(static_all);
- test_structs(dynamic_all);
- test_structs(runtime_partial);
- test_structs(runtime_all);
- test_structs(assigned_static_partial);
- test_structs(assigned_static_all);
- test_structs(assigned_dynamic_all);
+ KUNIT_test_structs(static_partial),
+ KUNIT_test_structs(static_all),
+ KUNIT_test_structs(dynamic_all),
+ KUNIT_test_structs(runtime_partial),
+ KUNIT_test_structs(runtime_all),
+ KUNIT_test_structs(assigned_static_partial),
+ KUNIT_test_structs(assigned_static_all),
+ KUNIT_test_structs(assigned_dynamic_all),
/* Everything fails this since it effectively performs a memcpy(). */
- test_structs(assigned_copy);
-
+ KUNIT_test_structs(assigned_copy),
/* STRUCTLEAK_BYREF_ALL should cover everything from here down. */
- test_scalars(none);
- failures += test_switch_1_none();
- failures += test_switch_2_none();
-
+ KUNIT_test_scalars(none),
+ KUNIT_CASE(test_switch_1_none),
+ KUNIT_CASE(test_switch_2_none),
/* STRUCTLEAK_BYREF should cover from here down. */
- test_structs(none);
-
+ KUNIT_test_structs(none),
/* STRUCTLEAK will only cover this. */
- failures += test_user();
-
- if (failures == 0)
- pr_info("all tests passed!\n");
- else
- pr_err("failures: %u\n", failures);
+ KUNIT_CASE(test_user),
+ {}
+};

- return failures ? -EINVAL : 0;
-}
-module_init(test_stackinit_init);
+static struct kunit_suite stackinit_test_suite = {
+ .name = "stackinit",
+ .test_cases = stackinit_test_cases,
+};

-static void __exit test_stackinit_exit(void)
-{ }
-module_exit(test_stackinit_exit);
+kunit_test_suites(&stackinit_test_suite);

MODULE_LICENSE("GPL");
--
2.32.0