threading_helpers.c (13104B)
1 /** Mutex usage verification framework. */ 2 3 /* 4 * Copyright The Mbed TLS Contributors 5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 6 */ 7 8 #include <test/helpers.h> 9 #include <test/threading_helpers.h> 10 #include <test/macros.h> 11 12 #include "mbedtls/threading.h" 13 14 #if defined(MBEDTLS_THREADING_C) 15 16 #if defined(MBEDTLS_THREADING_PTHREAD) 17 18 static int threading_thread_create_pthread(mbedtls_test_thread_t *thread, void *(*thread_func)( 19 void *), void *thread_data) 20 { 21 if (thread == NULL || thread_func == NULL) { 22 return MBEDTLS_ERR_THREADING_BAD_INPUT_DATA; 23 } 24 25 if (pthread_create(&thread->thread, NULL, thread_func, thread_data)) { 26 return MBEDTLS_ERR_THREADING_THREAD_ERROR; 27 } 28 29 return 0; 30 } 31 32 static int threading_thread_join_pthread(mbedtls_test_thread_t *thread) 33 { 34 if (thread == NULL) { 35 return MBEDTLS_ERR_THREADING_BAD_INPUT_DATA; 36 } 37 38 if (pthread_join(thread->thread, NULL) != 0) { 39 return MBEDTLS_ERR_THREADING_THREAD_ERROR; 40 } 41 42 return 0; 43 } 44 45 int (*mbedtls_test_thread_create)(mbedtls_test_thread_t *thread, void *(*thread_func)(void *), 46 void *thread_data) = threading_thread_create_pthread; 47 int (*mbedtls_test_thread_join)(mbedtls_test_thread_t *thread) = threading_thread_join_pthread; 48 49 #endif /* MBEDTLS_THREADING_PTHREAD */ 50 51 #if defined(MBEDTLS_THREADING_ALT) 52 53 static int threading_thread_create_fail(mbedtls_test_thread_t *thread, 54 void *(*thread_func)(void *), 55 void *thread_data) 56 { 57 (void) thread; 58 (void) thread_func; 59 (void) thread_data; 60 61 return MBEDTLS_ERR_THREADING_BAD_INPUT_DATA; 62 } 63 64 static int threading_thread_join_fail(mbedtls_test_thread_t *thread) 65 { 66 (void) thread; 67 68 return MBEDTLS_ERR_THREADING_BAD_INPUT_DATA; 69 } 70 71 int (*mbedtls_test_thread_create)(mbedtls_test_thread_t *thread, void *(*thread_func)(void *), 72 void *thread_data) = threading_thread_create_fail; 73 int (*mbedtls_test_thread_join)(mbedtls_test_thread_t *thread) = threading_thread_join_fail; 74 75 #endif /* MBEDTLS_THREADING_ALT */ 76 77 #if defined(MBEDTLS_TEST_MUTEX_USAGE) 78 79 #include "mbedtls/threading.h" 80 81 /** Mutex usage verification framework. 82 * 83 * The mutex usage verification code below aims to detect bad usage of 84 * Mbed TLS's mutex abstraction layer at runtime. Note that this is solely 85 * about the use of the mutex itself, not about checking whether the mutex 86 * correctly protects whatever it is supposed to protect. 87 * 88 * The normal usage of a mutex is: 89 * ``` 90 * digraph mutex_states { 91 * "UNINITIALIZED"; // the initial state 92 * "IDLE"; 93 * "FREED"; 94 * "LOCKED"; 95 * "UNINITIALIZED" -> "IDLE" [label="init"]; 96 * "FREED" -> "IDLE" [label="init"]; 97 * "IDLE" -> "LOCKED" [label="lock"]; 98 * "LOCKED" -> "IDLE" [label="unlock"]; 99 * "IDLE" -> "FREED" [label="free"]; 100 * } 101 * ``` 102 * 103 * All bad transitions that can be unambiguously detected are reported. 104 * An attempt to use an uninitialized mutex cannot be detected in general 105 * since the memory content may happen to denote a valid state. For the same 106 * reason, a double init cannot be detected. 107 * All-bits-zero is the state of a freed mutex, which is distinct from an 108 * initialized mutex, so attempting to use zero-initialized memory as a mutex 109 * without calling the init function is detected. 110 * 111 * The framework attempts to detect missing calls to init and free by counting 112 * calls to init and free. If there are more calls to init than free, this 113 * means that a mutex is not being freed somewhere, which is a memory leak 114 * on platforms where a mutex consumes resources other than the 115 * mbedtls_threading_mutex_t object itself. If there are more calls to free 116 * than init, this indicates a missing init, which is likely to be detected 117 * by an attempt to lock the mutex as well. A limitation of this framework is 118 * that it cannot detect scenarios where there is exactly the same number of 119 * calls to init and free but the calls don't match. A bug like this is 120 * unlikely to happen uniformly throughout the whole test suite though. 121 * 122 * If an error is detected, this framework will report what happened and the 123 * test case will be marked as failed. Unfortunately, the error report cannot 124 * indicate the exact location of the problematic call. To locate the error, 125 * use a debugger and set a breakpoint on mbedtls_test_mutex_usage_error(). 126 */ 127 enum value_of_mutex_state_field { 128 /* Potential values for the state field of mbedtls_threading_mutex_t. 129 * Note that MUTEX_FREED must be 0 and MUTEX_IDLE must be 1 for 130 * compatibility with threading_mutex_init_pthread() and 131 * threading_mutex_free_pthread(). MUTEX_LOCKED could be any nonzero 132 * value. */ 133 MUTEX_FREED = 0, //! < Set by mbedtls_test_wrap_mutex_free 134 MUTEX_IDLE = 1, //! < Set by mbedtls_test_wrap_mutex_init and by mbedtls_test_wrap_mutex_unlock 135 MUTEX_LOCKED = 2, //! < Set by mbedtls_test_wrap_mutex_lock 136 }; 137 138 typedef struct { 139 void (*init)(mbedtls_threading_mutex_t *); 140 void (*free)(mbedtls_threading_mutex_t *); 141 int (*lock)(mbedtls_threading_mutex_t *); 142 int (*unlock)(mbedtls_threading_mutex_t *); 143 } mutex_functions_t; 144 static mutex_functions_t mutex_functions; 145 146 /** 147 * The mutex used to guard live_mutexes below and access to the status variable 148 * in every mbedtls_threading_mutex_t. 149 * Note that we are not reporting any errors when locking and unlocking this 150 * mutex. This is for a couple of reasons: 151 * 152 * 1. We have no real way of reporting any errors with this mutex - we cannot 153 * report it back to the caller, as the failure was not that of the mutex 154 * passed in. We could fail the test, but again this would indicate a problem 155 * with the test code that did not exist. 156 * 157 * 2. Any failure to lock is unlikely to be intermittent, and will thus not 158 * give false test results - the overall result would be to turn off the 159 * testing. This is not a situation that is likely to happen with normal 160 * testing and we still have TSan to fall back on should this happen. 161 */ 162 mbedtls_threading_mutex_t mbedtls_test_mutex_mutex; 163 164 /** 165 * The total number of calls to mbedtls_mutex_init(), minus the total number 166 * of calls to mbedtls_mutex_free(). 167 * 168 * Do not read or write without holding mbedtls_test_mutex_mutex (above). Reset 169 * to 0 after each test case. 170 */ 171 static int live_mutexes; 172 173 static void mbedtls_test_mutex_usage_error(mbedtls_threading_mutex_t *mutex, 174 const char *msg) 175 { 176 (void) mutex; 177 178 mbedtls_test_set_mutex_usage_error(msg); 179 mbedtls_fprintf(stdout, "[mutex: %s] ", msg); 180 /* Don't mark the test as failed yet. This way, if the test fails later 181 * for a functional reason, the test framework will report the message 182 * and location for this functional reason. If the test passes, 183 * mbedtls_test_mutex_usage_check() will mark it as failed. */ 184 } 185 186 static int mbedtls_test_mutex_can_test(mbedtls_threading_mutex_t *mutex) 187 { 188 /* If we attempt to run tests on this mutex then we are going to run into a 189 * couple of problems: 190 * 1. If any test on this mutex fails, we are going to deadlock when 191 * reporting that failure, as we already hold the mutex at that point. 192 * 2. Given the 'global' position of the initialization and free of this 193 * mutex, it will be shown as leaked on the first test run. */ 194 if (mutex == mbedtls_test_get_info_mutex()) { 195 return 0; 196 } 197 198 return 1; 199 } 200 201 static void mbedtls_test_wrap_mutex_init(mbedtls_threading_mutex_t *mutex) 202 { 203 mutex_functions.init(mutex); 204 205 if (mbedtls_test_mutex_can_test(mutex)) { 206 if (mutex_functions.lock(&mbedtls_test_mutex_mutex) == 0) { 207 mutex->state = MUTEX_IDLE; 208 ++live_mutexes; 209 210 mutex_functions.unlock(&mbedtls_test_mutex_mutex); 211 } 212 } 213 } 214 215 static void mbedtls_test_wrap_mutex_free(mbedtls_threading_mutex_t *mutex) 216 { 217 if (mbedtls_test_mutex_can_test(mutex)) { 218 if (mutex_functions.lock(&mbedtls_test_mutex_mutex) == 0) { 219 220 switch (mutex->state) { 221 case MUTEX_FREED: 222 mbedtls_test_mutex_usage_error(mutex, "free without init or double free"); 223 break; 224 case MUTEX_IDLE: 225 mutex->state = MUTEX_FREED; 226 --live_mutexes; 227 break; 228 case MUTEX_LOCKED: 229 mbedtls_test_mutex_usage_error(mutex, "free without unlock"); 230 break; 231 default: 232 mbedtls_test_mutex_usage_error(mutex, "corrupted state"); 233 break; 234 } 235 236 mutex_functions.unlock(&mbedtls_test_mutex_mutex); 237 } 238 } 239 240 mutex_functions.free(mutex); 241 } 242 243 static int mbedtls_test_wrap_mutex_lock(mbedtls_threading_mutex_t *mutex) 244 { 245 /* Lock the passed in mutex first, so that the only way to change the state 246 * is to hold the passed in and internal mutex - otherwise we create a race 247 * condition. */ 248 int ret = mutex_functions.lock(mutex); 249 250 if (mbedtls_test_mutex_can_test(mutex)) { 251 if (mutex_functions.lock(&mbedtls_test_mutex_mutex) == 0) { 252 switch (mutex->state) { 253 case MUTEX_FREED: 254 mbedtls_test_mutex_usage_error(mutex, "lock without init"); 255 break; 256 case MUTEX_IDLE: 257 if (ret == 0) { 258 mutex->state = MUTEX_LOCKED; 259 } 260 break; 261 case MUTEX_LOCKED: 262 mbedtls_test_mutex_usage_error(mutex, "double lock"); 263 break; 264 default: 265 mbedtls_test_mutex_usage_error(mutex, "corrupted state"); 266 break; 267 } 268 269 mutex_functions.unlock(&mbedtls_test_mutex_mutex); 270 } 271 } 272 273 return ret; 274 } 275 276 static int mbedtls_test_wrap_mutex_unlock(mbedtls_threading_mutex_t *mutex) 277 { 278 /* Lock the internal mutex first and change state, so that the only way to 279 * change the state is to hold the passed in and internal mutex - otherwise 280 * we create a race condition. */ 281 if (mbedtls_test_mutex_can_test(mutex)) { 282 if (mutex_functions.lock(&mbedtls_test_mutex_mutex) == 0) { 283 switch (mutex->state) { 284 case MUTEX_FREED: 285 mbedtls_test_mutex_usage_error(mutex, "unlock without init"); 286 break; 287 case MUTEX_IDLE: 288 mbedtls_test_mutex_usage_error(mutex, "unlock without lock"); 289 break; 290 case MUTEX_LOCKED: 291 mutex->state = MUTEX_IDLE; 292 break; 293 default: 294 mbedtls_test_mutex_usage_error(mutex, "corrupted state"); 295 break; 296 } 297 mutex_functions.unlock(&mbedtls_test_mutex_mutex); 298 } 299 } 300 301 return mutex_functions.unlock(mutex); 302 } 303 304 void mbedtls_test_mutex_usage_init(void) 305 { 306 mutex_functions.init = mbedtls_mutex_init; 307 mutex_functions.free = mbedtls_mutex_free; 308 mutex_functions.lock = mbedtls_mutex_lock; 309 mutex_functions.unlock = mbedtls_mutex_unlock; 310 mbedtls_mutex_init = &mbedtls_test_wrap_mutex_init; 311 mbedtls_mutex_free = &mbedtls_test_wrap_mutex_free; 312 mbedtls_mutex_lock = &mbedtls_test_wrap_mutex_lock; 313 mbedtls_mutex_unlock = &mbedtls_test_wrap_mutex_unlock; 314 315 mutex_functions.init(&mbedtls_test_mutex_mutex); 316 } 317 318 void mbedtls_test_mutex_usage_check(void) 319 { 320 if (mutex_functions.lock(&mbedtls_test_mutex_mutex) == 0) { 321 if (live_mutexes != 0) { 322 /* A positive number (more init than free) means that a mutex resource 323 * is leaking (on platforms where a mutex consumes more than the 324 * mbedtls_threading_mutex_t object itself). The (hopefully) rare 325 * case of a negative number means a missing init somewhere. */ 326 mbedtls_fprintf(stdout, "[mutex: %d leaked] ", live_mutexes); 327 live_mutexes = 0; 328 mbedtls_test_set_mutex_usage_error("missing free"); 329 } 330 if (mbedtls_test_get_mutex_usage_error() != NULL && 331 mbedtls_test_get_result() != MBEDTLS_TEST_RESULT_FAILED) { 332 /* Functionally, the test passed. But there was a mutex usage error, 333 * so mark the test as failed after all. */ 334 mbedtls_test_fail("Mutex usage error", __LINE__, __FILE__); 335 } 336 mbedtls_test_set_mutex_usage_error(NULL); 337 338 mutex_functions.unlock(&mbedtls_test_mutex_mutex); 339 } 340 } 341 342 void mbedtls_test_mutex_usage_end(void) 343 { 344 mbedtls_mutex_init = mutex_functions.init; 345 mbedtls_mutex_free = mutex_functions.free; 346 mbedtls_mutex_lock = mutex_functions.lock; 347 mbedtls_mutex_unlock = mutex_functions.unlock; 348 349 mutex_functions.free(&mbedtls_test_mutex_mutex); 350 } 351 352 #endif /* MBEDTLS_TEST_MUTEX_USAGE */ 353 354 #endif /* MBEDTLS_THREADING_C */