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Diffstat (limited to 'lib/stackinit_kunit.c')
| -rw-r--r-- | lib/stackinit_kunit.c | 461 |
1 files changed, 461 insertions, 0 deletions
diff --git a/lib/stackinit_kunit.c b/lib/stackinit_kunit.c new file mode 100644 index 000000000000..05947a2feb93 --- /dev/null +++ b/lib/stackinit_kunit.c @@ -0,0 +1,461 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Test cases for compiler-based stack variable zeroing via + * -ftrivial-auto-var-init={zero,pattern} or CONFIG_GCC_PLUGIN_STRUCTLEAK*. + * For example, see: + * "Running tests with kunit_tool" at Documentation/dev-tools/kunit/start.rst + * ./tools/testing/kunit/kunit.py run stackinit [--raw_output] \ + * --make_option LLVM=1 \ + * --kconfig_add CONFIG_INIT_STACK_ALL_ZERO=y + * + */ +#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> + +/* Exfiltration buffer. */ +#define MAX_VAR_SIZE 128 +static u8 check_buf[MAX_VAR_SIZE]; + +/* Character array to trigger stack protector in all functions. */ +#define VAR_BUFFER 32 + +/* Volatile mask to convince compiler to copy memory with 0xff. */ +static volatile u8 forced_mask = 0xff; + +/* Location and size tracking to validate fill and test are colocated. */ +static void *fill_start, *target_start; +static size_t fill_size, target_size; + +static bool stackinit_range_contains(char *haystack_start, size_t haystack_size, + char *needle_start, size_t needle_size) +{ + if (needle_start >= haystack_start && + needle_start + needle_size <= haystack_start + haystack_size) + return true; + return false; +} + +/* Whether the test is expected to fail. */ +#define WANT_SUCCESS 0 +#define XFAIL 1 + +#define DO_NOTHING_TYPE_SCALAR(var_type) var_type +#define DO_NOTHING_TYPE_STRING(var_type) void +#define DO_NOTHING_TYPE_STRUCT(var_type) void + +#define DO_NOTHING_RETURN_SCALAR(ptr) *(ptr) +#define DO_NOTHING_RETURN_STRING(ptr) /**/ +#define DO_NOTHING_RETURN_STRUCT(ptr) /**/ + +#define DO_NOTHING_CALL_SCALAR(var, name) \ + (var) = do_nothing_ ## name(&(var)) +#define DO_NOTHING_CALL_STRING(var, name) \ + do_nothing_ ## name(var) +#define DO_NOTHING_CALL_STRUCT(var, name) \ + do_nothing_ ## name(&(var)) + +#define FETCH_ARG_SCALAR(var) &var +#define FETCH_ARG_STRING(var) var +#define FETCH_ARG_STRUCT(var) &var + +#define FILL_SIZE_STRING 16 + +#define INIT_CLONE_SCALAR /**/ +#define INIT_CLONE_STRING [FILL_SIZE_STRING] +#define INIT_CLONE_STRUCT /**/ + +#define ZERO_CLONE_SCALAR(zero) memset(&(zero), 0x00, sizeof(zero)) +#define ZERO_CLONE_STRING(zero) memset(&(zero), 0x00, sizeof(zero)) +/* + * For the struct, intentionally poison padding to see if it gets + * copied out in direct assignments. + * */ +#define ZERO_CLONE_STRUCT(zero) \ + do { \ + memset(&(zero), 0xFF, sizeof(zero)); \ + zero.one = 0; \ + zero.two = 0; \ + zero.three = 0; \ + zero.four = 0; \ + } while (0) + +#define INIT_SCALAR_none(var_type) /**/ +#define INIT_SCALAR_zero(var_type) = 0 + +#define INIT_STRING_none(var_type) [FILL_SIZE_STRING] /**/ +#define INIT_STRING_zero(var_type) [FILL_SIZE_STRING] = { } + +#define INIT_STRUCT_none(var_type) /**/ +#define INIT_STRUCT_zero(var_type) = { } + + +#define __static_partial { .two = 0, } +#define __static_all { .one = 0, \ + .two = 0, \ + .three = 0, \ + .four = 0, \ + } +#define __dynamic_partial { .two = arg->two, } +#define __dynamic_all { .one = arg->one, \ + .two = arg->two, \ + .three = arg->three, \ + .four = arg->four, \ + } +#define __runtime_partial var.two = 0 +#define __runtime_all var.one = 0; \ + var.two = 0; \ + var.three = 0; \ + var.four = 0 + +#define INIT_STRUCT_static_partial(var_type) \ + = __static_partial +#define INIT_STRUCT_static_all(var_type) \ + = __static_all +#define INIT_STRUCT_dynamic_partial(var_type) \ + = __dynamic_partial +#define INIT_STRUCT_dynamic_all(var_type) \ + = __dynamic_all +#define INIT_STRUCT_runtime_partial(var_type) \ + ; __runtime_partial +#define INIT_STRUCT_runtime_all(var_type) \ + ; __runtime_all + +#define INIT_STRUCT_assigned_static_partial(var_type) \ + ; var = (var_type)__static_partial +#define INIT_STRUCT_assigned_static_all(var_type) \ + ; var = (var_type)__static_all +#define INIT_STRUCT_assigned_dynamic_partial(var_type) \ + ; var = (var_type)__dynamic_partial +#define INIT_STRUCT_assigned_dynamic_all(var_type) \ + ; var = (var_type)__dynamic_all + +#define INIT_STRUCT_assigned_copy(var_type) \ + ; var = *(arg) + +/* + * @name: unique string name for the test + * @var_type: type to be tested for zeroing initialization + * @which: is this a SCALAR, STRING, or STRUCT type? + * @init_level: what kind of initialization is performed + * @xfail: is this test expected to fail? + */ +#define DEFINE_TEST_DRIVER(name, var_type, which, xfail) \ +/* Returns 0 on success, 1 on failure. */ \ +static noinline void test_ ## name (struct kunit *test) \ +{ \ + var_type zero INIT_CLONE_ ## which; \ + int ignored; \ + u8 sum = 0, i; \ + \ + /* Notice when a new test is larger than expected. */ \ + BUILD_BUG_ON(sizeof(zero) > MAX_VAR_SIZE); \ + \ + /* Fill clone type with zero for per-field init. */ \ + ZERO_CLONE_ ## which(zero); \ + /* Clear entire check buffer for 0xFF overlap test. */ \ + memset(check_buf, 0x00, sizeof(check_buf)); \ + /* Fill stack with 0xFF. */ \ + ignored = leaf_ ##name((unsigned long)&ignored, 1, \ + FETCH_ARG_ ## which(zero)); \ + /* Verify all bytes overwritten with 0xFF. */ \ + for (sum = 0, i = 0; i < target_size; i++) \ + sum += (check_buf[i] != 0xFF); \ + 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. */ \ + ignored = leaf_ ##name((unsigned long)&ignored, 0, \ + FETCH_ARG_ ## which(zero)); \ + \ + /* Validate that compiler lined up fill and target. */ \ + KUNIT_ASSERT_TRUE_MSG(test, \ + stackinit_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 && 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 DO_NOTHING_TYPE_ ## which(var_type) \ +do_nothing_ ## name(var_type *ptr) \ +{ \ + /* Will always be true, but compiler doesn't know. */ \ + if ((unsigned long)ptr > 0x2) \ + return DO_NOTHING_RETURN_ ## which(ptr); \ + else \ + return DO_NOTHING_RETURN_ ## which(ptr + 1); \ +} \ +static noinline int leaf_ ## name(unsigned long sp, bool fill, \ + var_type *arg) \ +{ \ + char buf[VAR_BUFFER]; \ + var_type var \ + INIT_ ## which ## _ ## init_level(var_type); \ + \ + target_start = &var; \ + target_size = sizeof(var); \ + /* \ + * Keep this buffer around to make sure we've got a \ + * stack frame of SOME kind... \ + */ \ + memset(buf, (char)(sp & 0xff), sizeof(buf)); \ + /* Fill variable with 0xFF. */ \ + if (fill) { \ + fill_start = &var; \ + fill_size = sizeof(var); \ + memset(fill_start, \ + (char)((sp & 0xff) | forced_mask), \ + fill_size); \ + } \ + \ + /* Silence "never initialized" warnings. */ \ + DO_NOTHING_CALL_ ## which(var, name); \ + \ + /* Exfiltrate "var". */ \ + memcpy(check_buf, target_start, target_size); \ + \ + return (int)buf[0] | (int)buf[sizeof(buf) - 1]; \ +} \ +DEFINE_TEST_DRIVER(name, var_type, which, xfail) + +/* Structure with no padding. */ +struct test_packed { + unsigned long one; + unsigned long two; + unsigned long three; + unsigned long four; +}; + +/* Simple structure with padding likely to be covered by compiler. */ +struct test_small_hole { + size_t one; + char two; + /* 3 byte padding hole here. */ + int three; + unsigned long four; +}; + +/* Trigger unhandled padding in a structure. */ +struct test_big_hole { + u8 one; + u8 two; + u8 three; + /* 61 byte padding hole here. */ + u8 four __aligned(64); +} __aligned(64); + +struct test_trailing_hole { + char *one; + char *two; + char *three; + char four; + /* "sizeof(unsigned long) - 1" byte padding hole here. */ +}; + +/* Test if STRUCTLEAK is clearing structs with __user fields. */ +struct test_user { + u8 one; + unsigned long two; + char __user *three; + 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) + +#define DEFINE_SCALAR_TESTS(init, xfail) \ + DEFINE_SCALAR_TEST(u8, init, xfail); \ + DEFINE_SCALAR_TEST(u16, init, xfail); \ + DEFINE_SCALAR_TEST(u32, init, xfail); \ + DEFINE_SCALAR_TEST(u64, init, xfail); \ + DEFINE_TEST(char_array_ ## init, unsigned char, \ + STRING, init, xfail) + +#define DEFINE_STRUCT_TEST(name, init, xfail) \ + DEFINE_TEST(name ## _ ## init, \ + struct test_ ## name, STRUCT, init, \ + xfail) + +#define DEFINE_STRUCT_TESTS(init, xfail) \ + DEFINE_STRUCT_TEST(small_hole, init, xfail); \ + DEFINE_STRUCT_TEST(big_hole, init, xfail); \ + DEFINE_STRUCT_TEST(trailing_hole, init, xfail); \ + DEFINE_STRUCT_TEST(packed, init, xfail) + +#define DEFINE_STRUCT_INITIALIZER_TESTS(base, xfail) \ + DEFINE_STRUCT_TESTS(base ## _ ## partial, \ + xfail); \ + DEFINE_STRUCT_TESTS(base ## _ ## all, xfail) + +/* These should be fully initialized all the time! */ +DEFINE_SCALAR_TESTS(zero, ALWAYS_PASS); +DEFINE_STRUCT_TESTS(zero, ALWAYS_PASS); +/* Struct initializers: padding may be left uninitialized. */ +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, STRONG_PASS); +DEFINE_STRUCT_TESTS(none, BYREF_PASS); +/* Initialization of members with __user attribute. */ +DEFINE_TEST(user, struct test_user, STRUCT, none, USER_PASS); + +/* + * Check two uses through a variable declaration outside either path, + * which was noticed as a special case in porting earlier stack init + * compiler logic. + */ +static int noinline __leaf_switch_none(int path, bool fill) +{ + switch (path) { + /* + * This is intentionally unreachable. To silence the + * warning, build with -Wno-switch-unreachable + */ + uint64_t var[10]; + + case 1: + target_start = &var; + target_size = sizeof(var); + if (fill) { + fill_start = &var; + fill_size = sizeof(var); + + memset(fill_start, forced_mask | 0x55, fill_size); + } + memcpy(check_buf, target_start, target_size); + break; + case 2: + target_start = &var; + target_size = sizeof(var); + if (fill) { + fill_start = &var; + fill_size = sizeof(var); + + memset(fill_start, forced_mask | 0xaa, fill_size); + } + memcpy(check_buf, target_start, target_size); + break; + default: + var[1] = 5; + return var[1] & forced_mask; + } + return 0; +} + +static noinline int leaf_switch_1_none(unsigned long sp, bool fill, + uint64_t *arg) +{ + return __leaf_switch_none(1, fill); +} + +static noinline int leaf_switch_2_none(unsigned long sp, bool fill, + uint64_t *arg) +{ + return __leaf_switch_none(2, fill); +} + +/* + * These are expected to fail for most configurations because neither + * GCC nor Clang have a way to perform initialization of variables in + * 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, 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. */ + KUNIT_test_scalars(zero), + KUNIT_test_structs(zero), + /* Padding here appears to be accidentally always initialized? */ + KUNIT_test_structs(dynamic_partial), + KUNIT_test_structs(assigned_dynamic_partial), + /* Padding initialization depends on compiler behaviors. */ + 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(). */ + KUNIT_test_structs(assigned_copy), + /* STRUCTLEAK_BYREF_ALL should cover everything from here down. */ + KUNIT_test_scalars(none), + KUNIT_CASE(test_switch_1_none), + KUNIT_CASE(test_switch_2_none), + /* STRUCTLEAK_BYREF should cover from here down. */ + KUNIT_test_structs(none), + /* STRUCTLEAK will only cover this. */ + KUNIT_CASE(test_user), + {} +}; + +static struct kunit_suite stackinit_test_suite = { + .name = "stackinit", + .test_cases = stackinit_test_cases, +}; + +kunit_test_suites(&stackinit_test_suite); + +MODULE_LICENSE("GPL"); |