Commit 02788ebc authored by Kees Cook's avatar Kees Cook
Browse files

lib: stackinit: Convert to KUnit



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: default avatarKees 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)
parent c7500c1b
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+11 −11
Original line number Diff line number Diff line
@@ -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
+2 −2
Original line number Diff line number Diff line
@@ -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

+108 −161
Original line number Diff line number Diff line
@@ -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",	\
	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));	\
		return 1;					\
	}							\
								\
	/* 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. */	\
@@ -265,8 +205,7 @@ 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,		\
static noinline int leaf_ ## name(unsigned long sp, bool fill,	\
				  var_type *arg)		\
{								\
	char buf[VAR_BUFFER];					\
@@ -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");