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kunit/fortify: Validate __alloc_size attribute results
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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>
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Kees Cook committed Nov 23, 2022
1 parent 0ad811c commit 9124a26
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Showing 2 changed files with 256 additions and 0 deletions.
1 change: 1 addition & 0 deletions lib/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -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
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255 changes: 255 additions & 0 deletions lib/fortify_kunit.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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!";
Expand Down Expand Up @@ -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),
{}
};

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