You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
402 lines
11 KiB
402 lines
11 KiB
// SPDX-Licenses: GPLv2
|
|
/*
|
|
* Test cases for compiler-based stack variable zeroing via future
|
|
* compiler flags or CONFIG_GCC_PLUGIN_STRUCTLEAK*.
|
|
*/
|
|
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
|
|
|
|
#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 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;
|
|
}
|
|
|
|
#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 INIT_SCALAR_none /**/
|
|
#define INIT_SCALAR_zero = 0
|
|
|
|
#define INIT_STRING_none [FILL_SIZE_STRING] /**/
|
|
#define INIT_STRING_zero [FILL_SIZE_STRING] = { }
|
|
|
|
#define INIT_STRUCT_none /**/
|
|
#define INIT_STRUCT_zero = { }
|
|
#define INIT_STRUCT_static_partial = { .two = 0, }
|
|
#define INIT_STRUCT_static_all = { .one = arg->one, \
|
|
.two = arg->two, \
|
|
.three = arg->three, \
|
|
.four = arg->four, \
|
|
}
|
|
#define INIT_STRUCT_dynamic_partial = { .two = arg->two, }
|
|
#define INIT_STRUCT_dynamic_all = { .one = arg->one, \
|
|
.two = arg->two, \
|
|
.three = arg->three, \
|
|
.four = arg->four, \
|
|
}
|
|
#define INIT_STRUCT_runtime_partial ; \
|
|
var.two = 0
|
|
#define INIT_STRUCT_runtime_all ; \
|
|
var.one = 0; \
|
|
var.two = 0; \
|
|
var.three = 0; \
|
|
memset(&var.four, 0, \
|
|
sizeof(var.four))
|
|
|
|
/*
|
|
* @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 __init int test_ ## name (void) \
|
|
{ \
|
|
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. */ \
|
|
memset(&zero, 0x00, sizeof(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); \
|
|
if (sum) { \
|
|
pr_err(#name ": leaf fill was not 0xFF!?\n"); \
|
|
return 1; \
|
|
} \
|
|
/* 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. */ \
|
|
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; \
|
|
} \
|
|
\
|
|
/* 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; \
|
|
} \
|
|
}
|
|
#define DEFINE_TEST(name, var_type, which, init_level) \
|
|
/* no-op to force compiler into ignoring "uninitialized" vars */\
|
|
static noinline __init 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 __init int leaf_ ## name(unsigned long sp, \
|
|
bool fill, \
|
|
var_type *arg) \
|
|
{ \
|
|
char buf[VAR_BUFFER]; \
|
|
var_type var INIT_ ## which ## _ ## init_level; \
|
|
\
|
|
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, 0)
|
|
|
|
/* 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;
|
|
};
|
|
|
|
/* Try to trigger unhandled padding in a structure. */
|
|
struct test_aligned {
|
|
u32 internal1;
|
|
u64 internal2;
|
|
} __aligned(64);
|
|
|
|
struct test_big_hole {
|
|
u8 one;
|
|
u8 two;
|
|
u8 three;
|
|
/* 61 byte padding hole here. */
|
|
struct test_aligned four;
|
|
} __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 DEFINE_SCALAR_TEST(name, init) \
|
|
DEFINE_TEST(name ## _ ## init, name, SCALAR, init)
|
|
|
|
#define DEFINE_SCALAR_TESTS(init) \
|
|
DEFINE_SCALAR_TEST(u8, init); \
|
|
DEFINE_SCALAR_TEST(u16, init); \
|
|
DEFINE_SCALAR_TEST(u32, init); \
|
|
DEFINE_SCALAR_TEST(u64, init); \
|
|
DEFINE_TEST(char_array_ ## init, unsigned char, STRING, init)
|
|
|
|
#define DEFINE_STRUCT_TEST(name, init) \
|
|
DEFINE_TEST(name ## _ ## init, \
|
|
struct test_ ## name, STRUCT, init)
|
|
|
|
#define DEFINE_STRUCT_TESTS(init) \
|
|
DEFINE_STRUCT_TEST(small_hole, init); \
|
|
DEFINE_STRUCT_TEST(big_hole, init); \
|
|
DEFINE_STRUCT_TEST(trailing_hole, init); \
|
|
DEFINE_STRUCT_TEST(packed, init)
|
|
|
|
/* These should be fully initialized all the time! */
|
|
DEFINE_SCALAR_TESTS(zero);
|
|
DEFINE_STRUCT_TESTS(zero);
|
|
/* Static initialization: padding may be left uninitialized. */
|
|
DEFINE_STRUCT_TESTS(static_partial);
|
|
DEFINE_STRUCT_TESTS(static_all);
|
|
/* Dynamic initialization: padding may be left uninitialized. */
|
|
DEFINE_STRUCT_TESTS(dynamic_partial);
|
|
DEFINE_STRUCT_TESTS(dynamic_all);
|
|
/* Runtime initialization: padding may be left uninitialized. */
|
|
DEFINE_STRUCT_TESTS(runtime_partial);
|
|
DEFINE_STRUCT_TESTS(runtime_all);
|
|
/* No initialization without compiler instrumentation. */
|
|
DEFINE_SCALAR_TESTS(none);
|
|
DEFINE_STRUCT_TESTS(none);
|
|
DEFINE_TEST(user, struct test_user, STRUCT, none);
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
uint64_t var;
|
|
|
|
switch (path) {
|
|
|
|
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 = 5;
|
|
return var & forced_mask;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static noinline __init 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,
|
|
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, 1);
|
|
DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, 1);
|
|
|
|
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)
|
|
|
|
/* These are explicitly initialized and should always pass. */
|
|
test_scalars(zero);
|
|
test_structs(zero);
|
|
/* Padding here appears to be accidentally always initialized? */
|
|
test_structs(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);
|
|
|
|
/* STRUCTLEAK_BYREF_ALL should cover everything from here down. */
|
|
test_scalars(none);
|
|
failures += test_switch_1_none();
|
|
failures += test_switch_2_none();
|
|
|
|
/* STRUCTLEAK_BYREF should cover from here down. */
|
|
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);
|
|
/*
|
|
* Android 4.14 only: if this test is built as part of the
|
|
* kernel, make the failure visible.
|
|
*/
|
|
panic("Test failed!\n");
|
|
}
|
|
|
|
return failures ? -EINVAL : 0;
|
|
}
|
|
module_init(test_stackinit_init);
|
|
|
|
static void __exit test_stackinit_exit(void)
|
|
{ }
|
|
module_exit(test_stackinit_exit);
|
|
|
|
MODULE_LICENSE("GPL");
|
|
|