kunit/fortify: Validate __alloc_size attribute results

Validate the effect of the __alloc_size attribute on allocators. If the
compiler doesn't support __builtin_dynamic_object_size(), skip the
associated tests.

(For GCC, just remove the "--make_options" line below...)

$ ./tools/testing/kunit/kunit.py run --arch x86_64 \
        --kconfig_add CONFIG_FORTIFY_SOURCE=y \
	--make_options LLVM=1
        fortify
...
[15:16:30] ================== fortify (10 subtests) ===================
[15:16:30] [PASSED] known_sizes_test
[15:16:30] [PASSED] control_flow_split_test
[15:16:30] [PASSED] alloc_size_kmalloc_const_test
[15:16:30] [PASSED] alloc_size_kmalloc_dynamic_test
[15:16:30] [PASSED] alloc_size_vmalloc_const_test
[15:16:30] [PASSED] alloc_size_vmalloc_dynamic_test
[15:16:30] [PASSED] alloc_size_kvmalloc_const_test
[15:16:30] [PASSED] alloc_size_kvmalloc_dynamic_test
[15:16:30] [PASSED] alloc_size_devm_kmalloc_const_test
[15:16:30] [PASSED] alloc_size_devm_kmalloc_dynamic_test
[15:16:30] ===================== [PASSED] fortify =====================
[15:16:30] ============================================================
[15:16:30] Testing complete. Ran 10 tests: passed: 10
[15:16:31] Elapsed time: 8.348s total, 0.002s configuring, 6.923s building, 1.075s running

For earlier GCC prior to version 12, the dynamic tests will be skipped:

[15:18:59] ================== fortify (10 subtests) ===================
[15:18:59] [PASSED] known_sizes_test
[15:18:59] [PASSED] control_flow_split_test
[15:18:59] [PASSED] alloc_size_kmalloc_const_test
[15:18:59] [SKIPPED] alloc_size_kmalloc_dynamic_test
[15:18:59] [PASSED] alloc_size_vmalloc_const_test
[15:18:59] [SKIPPED] alloc_size_vmalloc_dynamic_test
[15:18:59] [PASSED] alloc_size_kvmalloc_const_test
[15:18:59] [SKIPPED] alloc_size_kvmalloc_dynamic_test
[15:18:59] [PASSED] alloc_size_devm_kmalloc_const_test
[15:18:59] [SKIPPED] alloc_size_devm_kmalloc_dynamic_test
[15:18:59] ===================== [PASSED] fortify =====================
[15:18:59] ============================================================
[15:18:59] Testing complete. Ran 10 tests: passed: 6, skipped: 4
[15:18:59] Elapsed time: 11.965s total, 0.002s configuring, 10.540s building, 1.068s running

Cc: David Gow <davidgow@google.com>
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

lib/Makefile

@@ -378,6 +378,7 @@ CFLAGS_overflow_kunit.o = $(call cc-disable-warning, tautological-constant-out-o
 obj-$(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
+CFLAGS_fortify_kunit.o += $(call cc-disable-warning, unsequenced)
 obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o
 obj-$(CONFIG_STRSCPY_KUNIT_TEST) += strscpy_kunit.o
 obj-$(CONFIG_SIPHASH_KUNIT_TEST) += siphash_kunit.o

lib/fortify_kunit.c

@@ -16,7 +16,10 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <kunit/test.h>
+#include <linux/device.h>
+#include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/vmalloc.h>
 
 static const char array_of_10[] = "this is 10";
 static const char *ptr_of_11 = "this is 11!";
@@ -60,9 +63,261 @@ static void control_flow_split_test(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, want_minus_one(pick), SIZE_MAX);
 }
 
+#define KUNIT_EXPECT_BOS(test, p, expected, name)			\
+	KUNIT_EXPECT_EQ_MSG(test, __builtin_object_size(p, 1),		\
+		expected,						\
+		"__alloc_size() not working with __bos on " name "\n")
+
+#if !__has_builtin(__builtin_dynamic_object_size)
+#define KUNIT_EXPECT_BDOS(test, p, expected, name)			\
+	/* Silence "unused variable 'expected'" warning. */		\
+	KUNIT_EXPECT_EQ(test, expected, expected)
+#else
+#define KUNIT_EXPECT_BDOS(test, p, expected, name)			\
+	KUNIT_EXPECT_EQ_MSG(test, __builtin_dynamic_object_size(p, 1),	\
+		expected,						\
+		"__alloc_size() not working with __bdos on " name "\n")
+#endif
+
+/* If the execpted size is a constant value, __bos can see it. */
+#define check_const(_expected, alloc, free)		do {		\
+	size_t expected = (_expected);					\
+	void *p = alloc;						\
+	KUNIT_EXPECT_TRUE_MSG(test, p != NULL, #alloc " failed?!\n");	\
+	KUNIT_EXPECT_BOS(test, p, expected, #alloc);			\
+	KUNIT_EXPECT_BDOS(test, p, expected, #alloc);			\
+	free;								\
+} while (0)
+
+/* If the execpted size is NOT a constant value, __bos CANNOT see it. */
+#define check_dynamic(_expected, alloc, free)		do {		\
+	size_t expected = (_expected);					\
+	void *p = alloc;						\
+	KUNIT_EXPECT_TRUE_MSG(test, p != NULL, #alloc " failed?!\n");	\
+	KUNIT_EXPECT_BOS(test, p, SIZE_MAX, #alloc);			\
+	KUNIT_EXPECT_BDOS(test, p, expected, #alloc);			\
+	free;								\
+} while (0)
+
+/* Assortment of constant-value kinda-edge cases. */
+#define CONST_TEST_BODY(TEST_alloc)	do {				\
+	/* Special-case vmalloc()-family to skip 0-sized allocs. */	\
+	if (strcmp(#TEST_alloc, "TEST_vmalloc") != 0)			\
+		TEST_alloc(check_const, 0, 0);				\
+	TEST_alloc(check_const, 1, 1);					\
+	TEST_alloc(check_const, 128, 128);				\
+	TEST_alloc(check_const, 1023, 1023);				\
+	TEST_alloc(check_const, 1025, 1025);				\
+	TEST_alloc(check_const, 4096, 4096);				\
+	TEST_alloc(check_const, 4097, 4097);				\
+} while (0)
+
+static volatile size_t zero_size;
+static volatile size_t unknown_size = 50;
+
+#if !__has_builtin(__builtin_dynamic_object_size)
+#define DYNAMIC_TEST_BODY(TEST_alloc)					\
+	kunit_skip(test, "Compiler is missing __builtin_dynamic_object_size() support\n")
+#else
+#define DYNAMIC_TEST_BODY(TEST_alloc)	do {				\
+	size_t size = unknown_size;					\
+									\
+	/*								\
+	 * Expected size is "size" in each test, before it is then	\
+	 * internally incremented in each test.	Requires we disable	\
+	 * -Wunsequenced.						\
+	 */								\
+	TEST_alloc(check_dynamic, size, size++);			\
+	/* Make sure incrementing actually happened. */			\
+	KUNIT_EXPECT_NE(test, size, unknown_size);			\
+} while (0)
+#endif
+
+#define DEFINE_ALLOC_SIZE_TEST_PAIR(allocator)				\
+static void alloc_size_##allocator##_const_test(struct kunit *test)	\
+{									\
+	CONST_TEST_BODY(TEST_##allocator);				\
+}									\
+static void alloc_size_##allocator##_dynamic_test(struct kunit *test)	\
+{									\
+	DYNAMIC_TEST_BODY(TEST_##allocator);				\
+}
+
+#define TEST_kmalloc(checker, expected_size, alloc_size)	do {	\
+	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;				\
+	void *orig;							\
+	size_t len;							\
+									\
+	checker(expected_size, kmalloc(alloc_size, gfp),		\
+		kfree(p));						\
+	checker(expected_size,						\
+		kmalloc_node(alloc_size, gfp, NUMA_NO_NODE),		\
+		kfree(p));						\
+	checker(expected_size, kzalloc(alloc_size, gfp),		\
+		kfree(p));						\
+	checker(expected_size,						\
+		kzalloc_node(alloc_size, gfp, NUMA_NO_NODE),		\
+		kfree(p));						\
+	checker(expected_size, kcalloc(1, alloc_size, gfp),		\
+		kfree(p));						\
+	checker(expected_size, kcalloc(alloc_size, 1, gfp),		\
+		kfree(p));						\
+	checker(expected_size,						\
+		kcalloc_node(1, alloc_size, gfp, NUMA_NO_NODE),		\
+		kfree(p));						\
+	checker(expected_size,						\
+		kcalloc_node(alloc_size, 1, gfp, NUMA_NO_NODE),		\
+		kfree(p));						\
+	checker(expected_size, kmalloc_array(1, alloc_size, gfp),	\
+		kfree(p));						\
+	checker(expected_size, kmalloc_array(alloc_size, 1, gfp),	\
+		kfree(p));						\
+	checker(expected_size,						\
+		kmalloc_array_node(1, alloc_size, gfp, NUMA_NO_NODE),	\
+		kfree(p));						\
+	checker(expected_size,						\
+		kmalloc_array_node(alloc_size, 1, gfp, NUMA_NO_NODE),	\
+		kfree(p));						\
+	checker(expected_size, __kmalloc(alloc_size, gfp),		\
+		kfree(p));						\
+	checker(expected_size,						\
+		__kmalloc_node(alloc_size, gfp, NUMA_NO_NODE),		\
+		kfree(p));						\
+									\
+	orig = kmalloc(alloc_size, gfp);				\
+	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
+	checker((expected_size) * 2,					\
+		krealloc(orig, (alloc_size) * 2, gfp),			\
+		kfree(p));						\
+	orig = kmalloc(alloc_size, gfp);				\
+	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
+	checker((expected_size) * 2,					\
+		krealloc_array(orig, 1, (alloc_size) * 2, gfp),		\
+		kfree(p));						\
+	orig = kmalloc(alloc_size, gfp);				\
+	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
+	checker((expected_size) * 2,					\
+		krealloc_array(orig, (alloc_size) * 2, 1, gfp),		\
+		kfree(p));						\
+									\
+	len = 11;							\
+	/* Using memdup() with fixed size, so force unknown length. */	\
+	if (!__builtin_constant_p(expected_size))			\
+		len += zero_size;					\
+	checker(len, kmemdup("hello there", len, gfp), kfree(p));	\
+} while (0)
+DEFINE_ALLOC_SIZE_TEST_PAIR(kmalloc)
+
+/* Sizes are in pages, not bytes. */
+#define TEST_vmalloc(checker, expected_pages, alloc_pages)	do {	\
+	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;				\
+	checker((expected_pages) * PAGE_SIZE,				\
+		vmalloc((alloc_pages) * PAGE_SIZE),	   vfree(p));	\
+	checker((expected_pages) * PAGE_SIZE,				\
+		vzalloc((alloc_pages) * PAGE_SIZE),	   vfree(p));	\
+	checker((expected_pages) * PAGE_SIZE,				\
+		__vmalloc((alloc_pages) * PAGE_SIZE, gfp), vfree(p));	\
+} while (0)
+DEFINE_ALLOC_SIZE_TEST_PAIR(vmalloc)
+
+/* Sizes are in pages (and open-coded for side-effects), not bytes. */
+#define TEST_kvmalloc(checker, expected_pages, alloc_pages)	do {	\
+	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;				\
+	size_t prev_size;						\
+	void *orig;							\
+									\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvmalloc((alloc_pages) * PAGE_SIZE, gfp),		\
+		vfree(p));						\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvmalloc_node((alloc_pages) * PAGE_SIZE, gfp, NUMA_NO_NODE), \
+		vfree(p));						\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvzalloc((alloc_pages) * PAGE_SIZE, gfp),		\
+		vfree(p));						\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvzalloc_node((alloc_pages) * PAGE_SIZE, gfp, NUMA_NO_NODE), \
+		vfree(p));						\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvcalloc(1, (alloc_pages) * PAGE_SIZE, gfp),		\
+		vfree(p));						\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvcalloc((alloc_pages) * PAGE_SIZE, 1, gfp),		\
+		vfree(p));						\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvmalloc_array(1, (alloc_pages) * PAGE_SIZE, gfp),	\
+		vfree(p));						\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvmalloc_array((alloc_pages) * PAGE_SIZE, 1, gfp),	\
+		vfree(p));						\
+									\
+	prev_size = (expected_pages) * PAGE_SIZE;			\
+	orig = kvmalloc(prev_size, gfp);				\
+	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
+	checker(((expected_pages) * PAGE_SIZE) * 2,			\
+		kvrealloc(orig, prev_size,				\
+			  ((alloc_pages) * PAGE_SIZE) * 2, gfp),	\
+		kvfree(p));						\
+} while (0)
+DEFINE_ALLOC_SIZE_TEST_PAIR(kvmalloc)
+
+#define TEST_devm_kmalloc(checker, expected_size, alloc_size)	do {	\
+	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;				\
+	const char dev_name[] = "fortify-test";				\
+	struct device *dev;						\
+	void *orig;							\
+	size_t len;							\
+									\
+	/* Create dummy device for devm_kmalloc()-family tests. */	\
+	dev = root_device_register(dev_name);				\
+	KUNIT_ASSERT_FALSE_MSG(test, IS_ERR(dev),			\
+			       "Cannot register test device\n");	\
+									\
+	checker(expected_size, devm_kmalloc(dev, alloc_size, gfp),	\
+		devm_kfree(dev, p));					\
+	checker(expected_size, devm_kzalloc(dev, alloc_size, gfp),	\
+		devm_kfree(dev, p));					\
+	checker(expected_size,						\
+		devm_kmalloc_array(dev, 1, alloc_size, gfp),		\
+		devm_kfree(dev, p));					\
+	checker(expected_size,						\
+		devm_kmalloc_array(dev, alloc_size, 1, gfp),		\
+		devm_kfree(dev, p));					\
+	checker(expected_size,						\
+		devm_kcalloc(dev, 1, alloc_size, gfp),			\
+		devm_kfree(dev, p));					\
+	checker(expected_size,						\
+		devm_kcalloc(dev, alloc_size, 1, gfp),			\
+		devm_kfree(dev, p));					\
+									\
+	orig = devm_kmalloc(dev, alloc_size, gfp);			\
+	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
+	checker((expected_size) * 2,					\
+		devm_krealloc(dev, orig, (alloc_size) * 2, gfp),	\
+		devm_kfree(dev, p));					\
+									\
+	len = 4;							\
+	/* Using memdup() with fixed size, so force unknown length. */	\
+	if (!__builtin_constant_p(expected_size))			\
+		len += zero_size;					\
+	checker(len, devm_kmemdup(dev, "Ohai", len, gfp),		\
+		devm_kfree(dev, p));					\
+									\
+	device_unregister(dev);						\
+} while (0)
+DEFINE_ALLOC_SIZE_TEST_PAIR(devm_kmalloc)
+
 static struct kunit_case fortify_test_cases[] = {
 	KUNIT_CASE(known_sizes_test),
 	KUNIT_CASE(control_flow_split_test),
+	KUNIT_CASE(alloc_size_kmalloc_const_test),
+	KUNIT_CASE(alloc_size_kmalloc_dynamic_test),
+	KUNIT_CASE(alloc_size_vmalloc_const_test),
+	KUNIT_CASE(alloc_size_vmalloc_dynamic_test),
+	KUNIT_CASE(alloc_size_kvmalloc_const_test),
+	KUNIT_CASE(alloc_size_kvmalloc_dynamic_test),
+	KUNIT_CASE(alloc_size_devm_kmalloc_const_test),
+	KUNIT_CASE(alloc_size_devm_kmalloc_dynamic_test),
 	{}
 };