1 // SPDX-License-Identifier: GPL-2.0-only 2 #include <linux/kernel.h> 3 #include <linux/init.h> 4 #include <linux/prandom.h> 5 #include <linux/debugfs.h> 6 #include <linux/sched.h> 7 #include <linux/stat.h> 8 #include <linux/types.h> 9 #include <linux/fs.h> 10 #include <linux/export.h> 11 #include <linux/interrupt.h> 12 #include <linux/stacktrace.h> 13 #include <linux/fault-inject.h> 14 15 /* 16 * The should_fail() functions use prandom instead of the normal Linux RNG 17 * since they don't need cryptographically secure random numbers. 18 */ 19 static DEFINE_PER_CPU(struct rnd_state, fault_rnd_state); 20 21 static u32 fault_prandom_u32_below_100(void) 22 { 23 struct rnd_state *state; 24 u32 res; 25 26 state = &get_cpu_var(fault_rnd_state); 27 res = prandom_u32_state(state); 28 put_cpu_var(fault_rnd_state); 29 30 return res % 100; 31 } 32 33 /* 34 * setup_fault_attr() is a helper function for various __setup handlers, so it 35 * returns 0 on error, because that is what __setup handlers do. 36 */ 37 int setup_fault_attr(struct fault_attr *attr, char *str) 38 { 39 unsigned long probability; 40 unsigned long interval; 41 int times; 42 int space; 43 44 /* "<interval>,<probability>,<space>,<times>" */ 45 if (sscanf(str, "%lu,%lu,%d,%d", 46 &interval, &probability, &space, ×) < 4) { 47 printk(KERN_WARNING 48 "FAULT_INJECTION: failed to parse arguments\n"); 49 return 0; 50 } 51 52 prandom_init_once(&fault_rnd_state); 53 54 attr->probability = probability; 55 attr->interval = interval; 56 atomic_set(&attr->times, times); 57 atomic_set(&attr->space, space); 58 59 return 1; 60 } 61 EXPORT_SYMBOL_GPL(setup_fault_attr); 62 63 static void fail_dump(struct fault_attr *attr) 64 { 65 if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) { 66 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n" 67 "name %pd, interval %lu, probability %lu, " 68 "space %d, times %d\n", attr->dname, 69 attr->interval, attr->probability, 70 atomic_read(&attr->space), 71 atomic_read(&attr->times)); 72 if (attr->verbose > 1) 73 dump_stack(); 74 } 75 } 76 77 #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0) 78 79 static bool fail_task(struct fault_attr *attr, struct task_struct *task) 80 { 81 return in_task() && task->make_it_fail; 82 } 83 84 #define MAX_STACK_TRACE_DEPTH 32 85 86 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 87 88 static bool fail_stacktrace(struct fault_attr *attr) 89 { 90 int depth = attr->stacktrace_depth; 91 unsigned long entries[MAX_STACK_TRACE_DEPTH]; 92 int n, nr_entries; 93 bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX); 94 95 if (depth == 0 || (found && !attr->reject_start && !attr->reject_end)) 96 return found; 97 98 nr_entries = stack_trace_save(entries, depth, 1); 99 for (n = 0; n < nr_entries; n++) { 100 if (attr->reject_start <= entries[n] && 101 entries[n] < attr->reject_end) 102 return false; 103 if (attr->require_start <= entries[n] && 104 entries[n] < attr->require_end) 105 found = true; 106 } 107 return found; 108 } 109 110 #else 111 112 static inline bool fail_stacktrace(struct fault_attr *attr) 113 { 114 return true; 115 } 116 117 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 118 119 /* 120 * This code is stolen from failmalloc-1.0 121 * http://www.nongnu.org/failmalloc/ 122 */ 123 124 bool should_fail_ex(struct fault_attr *attr, ssize_t size, int flags) 125 { 126 bool stack_checked = false; 127 128 if (in_task()) { 129 unsigned int fail_nth = READ_ONCE(current->fail_nth); 130 131 if (fail_nth) { 132 if (!fail_stacktrace(attr)) 133 return false; 134 135 stack_checked = true; 136 fail_nth--; 137 WRITE_ONCE(current->fail_nth, fail_nth); 138 if (!fail_nth) 139 goto fail; 140 141 return false; 142 } 143 } 144 145 /* No need to check any other properties if the probability is 0 */ 146 if (attr->probability == 0) 147 return false; 148 149 if (attr->task_filter && !fail_task(attr, current)) 150 return false; 151 152 if (atomic_read(&attr->times) == 0) 153 return false; 154 155 if (!stack_checked && !fail_stacktrace(attr)) 156 return false; 157 158 if (atomic_read(&attr->space) > size) { 159 atomic_sub(size, &attr->space); 160 return false; 161 } 162 163 if (attr->interval > 1) { 164 attr->count++; 165 if (attr->count % attr->interval) 166 return false; 167 } 168 169 if (attr->probability <= fault_prandom_u32_below_100()) 170 return false; 171 172 fail: 173 if (!(flags & FAULT_NOWARN)) 174 fail_dump(attr); 175 176 if (atomic_read(&attr->times) != -1) 177 atomic_dec_not_zero(&attr->times); 178 179 return true; 180 } 181 182 bool should_fail(struct fault_attr *attr, ssize_t size) 183 { 184 return should_fail_ex(attr, size, 0); 185 } 186 EXPORT_SYMBOL_GPL(should_fail); 187 188 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS 189 190 static int debugfs_ul_set(void *data, u64 val) 191 { 192 *(unsigned long *)data = val; 193 return 0; 194 } 195 196 static int debugfs_ul_get(void *data, u64 *val) 197 { 198 *val = *(unsigned long *)data; 199 return 0; 200 } 201 202 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); 203 204 static void debugfs_create_ul(const char *name, umode_t mode, 205 struct dentry *parent, unsigned long *value) 206 { 207 debugfs_create_file(name, mode, parent, value, &fops_ul); 208 } 209 210 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 211 212 static int debugfs_stacktrace_depth_set(void *data, u64 val) 213 { 214 *(unsigned long *)data = 215 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH); 216 217 return 0; 218 } 219 220 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get, 221 debugfs_stacktrace_depth_set, "%llu\n"); 222 223 static void debugfs_create_stacktrace_depth(const char *name, umode_t mode, 224 struct dentry *parent, 225 unsigned long *value) 226 { 227 debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth); 228 } 229 230 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 231 232 struct dentry *fault_create_debugfs_attr(const char *name, 233 struct dentry *parent, struct fault_attr *attr) 234 { 235 umode_t mode = S_IFREG | S_IRUSR | S_IWUSR; 236 struct dentry *dir; 237 238 dir = debugfs_create_dir(name, parent); 239 if (IS_ERR(dir)) 240 return dir; 241 242 prandom_init_once(&fault_rnd_state); 243 244 debugfs_create_ul("probability", mode, dir, &attr->probability); 245 debugfs_create_ul("interval", mode, dir, &attr->interval); 246 debugfs_create_atomic_t("times", mode, dir, &attr->times); 247 debugfs_create_atomic_t("space", mode, dir, &attr->space); 248 debugfs_create_ul("verbose", mode, dir, &attr->verbose); 249 debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir, 250 &attr->ratelimit_state.interval); 251 debugfs_create_u32("verbose_ratelimit_burst", mode, dir, 252 &attr->ratelimit_state.burst); 253 debugfs_create_bool("task-filter", mode, dir, &attr->task_filter); 254 255 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 256 debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir, 257 &attr->stacktrace_depth); 258 debugfs_create_xul("require-start", mode, dir, &attr->require_start); 259 debugfs_create_xul("require-end", mode, dir, &attr->require_end); 260 debugfs_create_xul("reject-start", mode, dir, &attr->reject_start); 261 debugfs_create_xul("reject-end", mode, dir, &attr->reject_end); 262 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 263 264 attr->dname = dget(dir); 265 return dir; 266 } 267 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr); 268 269 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 270 271 #ifdef CONFIG_FAULT_INJECTION_CONFIGFS 272 273 /* These configfs attribute utilities are copied from drivers/block/null_blk/main.c */ 274 275 static ssize_t fault_uint_attr_show(unsigned int val, char *page) 276 { 277 return snprintf(page, PAGE_SIZE, "%u\n", val); 278 } 279 280 static ssize_t fault_ulong_attr_show(unsigned long val, char *page) 281 { 282 return snprintf(page, PAGE_SIZE, "%lu\n", val); 283 } 284 285 static ssize_t fault_bool_attr_show(bool val, char *page) 286 { 287 return snprintf(page, PAGE_SIZE, "%u\n", val); 288 } 289 290 static ssize_t fault_atomic_t_attr_show(atomic_t val, char *page) 291 { 292 return snprintf(page, PAGE_SIZE, "%d\n", atomic_read(&val)); 293 } 294 295 static ssize_t fault_uint_attr_store(unsigned int *val, const char *page, size_t count) 296 { 297 unsigned int tmp; 298 int result; 299 300 result = kstrtouint(page, 0, &tmp); 301 if (result < 0) 302 return result; 303 304 *val = tmp; 305 return count; 306 } 307 308 static ssize_t fault_ulong_attr_store(unsigned long *val, const char *page, size_t count) 309 { 310 int result; 311 unsigned long tmp; 312 313 result = kstrtoul(page, 0, &tmp); 314 if (result < 0) 315 return result; 316 317 *val = tmp; 318 return count; 319 } 320 321 static ssize_t fault_bool_attr_store(bool *val, const char *page, size_t count) 322 { 323 bool tmp; 324 int result; 325 326 result = kstrtobool(page, &tmp); 327 if (result < 0) 328 return result; 329 330 *val = tmp; 331 return count; 332 } 333 334 static ssize_t fault_atomic_t_attr_store(atomic_t *val, const char *page, size_t count) 335 { 336 int tmp; 337 int result; 338 339 result = kstrtoint(page, 0, &tmp); 340 if (result < 0) 341 return result; 342 343 atomic_set(val, tmp); 344 return count; 345 } 346 347 #define CONFIGFS_ATTR_NAMED(_pfx, _name, _attr_name) \ 348 static struct configfs_attribute _pfx##attr_##_name = { \ 349 .ca_name = _attr_name, \ 350 .ca_mode = 0644, \ 351 .ca_owner = THIS_MODULE, \ 352 .show = _pfx##_name##_show, \ 353 .store = _pfx##_name##_store, \ 354 } 355 356 static struct fault_config *to_fault_config(struct config_item *item) 357 { 358 return container_of(to_config_group(item), struct fault_config, group); 359 } 360 361 #define FAULT_CONFIGFS_ATTR_NAMED(NAME, ATTR_NAME, MEMBER, TYPE) \ 362 static ssize_t fault_##NAME##_show(struct config_item *item, char *page) \ 363 { \ 364 return fault_##TYPE##_attr_show(to_fault_config(item)->attr.MEMBER, page); \ 365 } \ 366 static ssize_t fault_##NAME##_store(struct config_item *item, const char *page, size_t count) \ 367 { \ 368 struct fault_config *config = to_fault_config(item); \ 369 return fault_##TYPE##_attr_store(&config->attr.MEMBER, page, count); \ 370 } \ 371 CONFIGFS_ATTR_NAMED(fault_, NAME, ATTR_NAME) 372 373 #define FAULT_CONFIGFS_ATTR(NAME, TYPE) \ 374 FAULT_CONFIGFS_ATTR_NAMED(NAME, __stringify(NAME), NAME, TYPE) 375 376 FAULT_CONFIGFS_ATTR(probability, ulong); 377 FAULT_CONFIGFS_ATTR(interval, ulong); 378 FAULT_CONFIGFS_ATTR(times, atomic_t); 379 FAULT_CONFIGFS_ATTR(space, atomic_t); 380 FAULT_CONFIGFS_ATTR(verbose, ulong); 381 FAULT_CONFIGFS_ATTR_NAMED(ratelimit_interval, "verbose_ratelimit_interval_ms", 382 ratelimit_state.interval, uint); 383 FAULT_CONFIGFS_ATTR_NAMED(ratelimit_burst, "verbose_ratelimit_burst", 384 ratelimit_state.burst, uint); 385 FAULT_CONFIGFS_ATTR_NAMED(task_filter, "task-filter", task_filter, bool); 386 387 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 388 389 static ssize_t fault_stacktrace_depth_show(struct config_item *item, char *page) 390 { 391 return fault_ulong_attr_show(to_fault_config(item)->attr.stacktrace_depth, page); 392 } 393 394 static ssize_t fault_stacktrace_depth_store(struct config_item *item, const char *page, 395 size_t count) 396 { 397 int result; 398 unsigned long tmp; 399 400 result = kstrtoul(page, 0, &tmp); 401 if (result < 0) 402 return result; 403 404 to_fault_config(item)->attr.stacktrace_depth = 405 min_t(unsigned long, tmp, MAX_STACK_TRACE_DEPTH); 406 407 return count; 408 } 409 410 CONFIGFS_ATTR_NAMED(fault_, stacktrace_depth, "stacktrace-depth"); 411 412 static ssize_t fault_xul_attr_show(unsigned long val, char *page) 413 { 414 return snprintf(page, PAGE_SIZE, 415 sizeof(val) == sizeof(u32) ? "0x%08lx\n" : "0x%016lx\n", val); 416 } 417 418 static ssize_t fault_xul_attr_store(unsigned long *val, const char *page, size_t count) 419 { 420 return fault_ulong_attr_store(val, page, count); 421 } 422 423 FAULT_CONFIGFS_ATTR_NAMED(require_start, "require-start", require_start, xul); 424 FAULT_CONFIGFS_ATTR_NAMED(require_end, "require-end", require_end, xul); 425 FAULT_CONFIGFS_ATTR_NAMED(reject_start, "reject-start", reject_start, xul); 426 FAULT_CONFIGFS_ATTR_NAMED(reject_end, "reject-end", reject_end, xul); 427 428 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 429 430 static struct configfs_attribute *fault_config_attrs[] = { 431 &fault_attr_probability, 432 &fault_attr_interval, 433 &fault_attr_times, 434 &fault_attr_space, 435 &fault_attr_verbose, 436 &fault_attr_ratelimit_interval, 437 &fault_attr_ratelimit_burst, 438 &fault_attr_task_filter, 439 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 440 &fault_attr_stacktrace_depth, 441 &fault_attr_require_start, 442 &fault_attr_require_end, 443 &fault_attr_reject_start, 444 &fault_attr_reject_end, 445 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 446 NULL, 447 }; 448 449 static const struct config_item_type fault_config_type = { 450 .ct_attrs = fault_config_attrs, 451 .ct_owner = THIS_MODULE, 452 }; 453 454 void fault_config_init(struct fault_config *config, const char *name) 455 { 456 prandom_init_once(&fault_rnd_state); 457 458 config_group_init_type_name(&config->group, name, &fault_config_type); 459 } 460 EXPORT_SYMBOL_GPL(fault_config_init); 461 462 #endif /* CONFIG_FAULT_INJECTION_CONFIGFS */ 463