1 // SPDX-License-Identifier: GPL-2.0-only 2 #include <linux/kernel.h> 3 #include <linux/init.h> 4 #include <linux/random.h> 5 #include <linux/sched.h> 6 #include <linux/stat.h> 7 #include <linux/types.h> 8 #include <linux/fs.h> 9 #include <linux/export.h> 10 #include <linux/interrupt.h> 11 #include <linux/stacktrace.h> 12 #include <linux/fault-inject.h> 13 14 /* 15 * setup_fault_attr() is a helper function for various __setup handlers, so it 16 * returns 0 on error, because that is what __setup handlers do. 17 */ 18 int setup_fault_attr(struct fault_attr *attr, char *str) 19 { 20 unsigned long probability; 21 unsigned long interval; 22 int times; 23 int space; 24 25 /* "<interval>,<probability>,<space>,<times>" */ 26 if (sscanf(str, "%lu,%lu,%d,%d", 27 &interval, &probability, &space, ×) < 4) { 28 printk(KERN_WARNING 29 "FAULT_INJECTION: failed to parse arguments\n"); 30 return 0; 31 } 32 33 attr->probability = probability; 34 attr->interval = interval; 35 atomic_set(&attr->times, times); 36 atomic_set(&attr->space, space); 37 38 return 1; 39 } 40 EXPORT_SYMBOL_GPL(setup_fault_attr); 41 42 static void fail_dump(struct fault_attr *attr) 43 { 44 if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) { 45 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n" 46 "name %pd, interval %lu, probability %lu, " 47 "space %d, times %d\n", attr->dname, 48 attr->interval, attr->probability, 49 atomic_read(&attr->space), 50 atomic_read(&attr->times)); 51 if (attr->verbose > 1) 52 dump_stack(); 53 } 54 } 55 56 #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0) 57 58 static bool fail_task(struct fault_attr *attr, struct task_struct *task) 59 { 60 return in_task() && task->make_it_fail; 61 } 62 63 #define MAX_STACK_TRACE_DEPTH 32 64 65 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 66 67 static bool fail_stacktrace(struct fault_attr *attr) 68 { 69 int depth = attr->stacktrace_depth; 70 unsigned long entries[MAX_STACK_TRACE_DEPTH]; 71 int n, nr_entries; 72 bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX); 73 74 if (depth == 0 || (found && !attr->reject_start && !attr->reject_end)) 75 return found; 76 77 nr_entries = stack_trace_save(entries, depth, 1); 78 for (n = 0; n < nr_entries; n++) { 79 if (attr->reject_start <= entries[n] && 80 entries[n] < attr->reject_end) 81 return false; 82 if (attr->require_start <= entries[n] && 83 entries[n] < attr->require_end) 84 found = true; 85 } 86 return found; 87 } 88 89 #else 90 91 static inline bool fail_stacktrace(struct fault_attr *attr) 92 { 93 return true; 94 } 95 96 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 97 98 /* 99 * This code is stolen from failmalloc-1.0 100 * http://www.nongnu.org/failmalloc/ 101 */ 102 103 bool should_fail_ex(struct fault_attr *attr, ssize_t size, int flags) 104 { 105 bool stack_checked = false; 106 107 if (in_task()) { 108 unsigned int fail_nth = READ_ONCE(current->fail_nth); 109 110 if (fail_nth) { 111 if (!fail_stacktrace(attr)) 112 return false; 113 114 stack_checked = true; 115 fail_nth--; 116 WRITE_ONCE(current->fail_nth, fail_nth); 117 if (!fail_nth) 118 goto fail; 119 120 return false; 121 } 122 } 123 124 /* No need to check any other properties if the probability is 0 */ 125 if (attr->probability == 0) 126 return false; 127 128 if (attr->task_filter && !fail_task(attr, current)) 129 return false; 130 131 if (atomic_read(&attr->times) == 0) 132 return false; 133 134 if (!stack_checked && !fail_stacktrace(attr)) 135 return false; 136 137 if (atomic_read(&attr->space) > size) { 138 atomic_sub(size, &attr->space); 139 return false; 140 } 141 142 if (attr->interval > 1) { 143 attr->count++; 144 if (attr->count % attr->interval) 145 return false; 146 } 147 148 if (attr->probability <= get_random_u32_below(100)) 149 return false; 150 151 fail: 152 if (!(flags & FAULT_NOWARN)) 153 fail_dump(attr); 154 155 if (atomic_read(&attr->times) != -1) 156 atomic_dec_not_zero(&attr->times); 157 158 return true; 159 } 160 161 bool should_fail(struct fault_attr *attr, ssize_t size) 162 { 163 return should_fail_ex(attr, size, 0); 164 } 165 EXPORT_SYMBOL_GPL(should_fail); 166 167 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS 168 169 static int debugfs_ul_set(void *data, u64 val) 170 { 171 *(unsigned long *)data = val; 172 return 0; 173 } 174 175 static int debugfs_ul_get(void *data, u64 *val) 176 { 177 *val = *(unsigned long *)data; 178 return 0; 179 } 180 181 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); 182 183 static void debugfs_create_ul(const char *name, umode_t mode, 184 struct dentry *parent, unsigned long *value) 185 { 186 debugfs_create_file(name, mode, parent, value, &fops_ul); 187 } 188 189 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 190 191 static int debugfs_stacktrace_depth_set(void *data, u64 val) 192 { 193 *(unsigned long *)data = 194 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH); 195 196 return 0; 197 } 198 199 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get, 200 debugfs_stacktrace_depth_set, "%llu\n"); 201 202 static void debugfs_create_stacktrace_depth(const char *name, umode_t mode, 203 struct dentry *parent, 204 unsigned long *value) 205 { 206 debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth); 207 } 208 209 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 210 211 struct dentry *fault_create_debugfs_attr(const char *name, 212 struct dentry *parent, struct fault_attr *attr) 213 { 214 umode_t mode = S_IFREG | S_IRUSR | S_IWUSR; 215 struct dentry *dir; 216 217 dir = debugfs_create_dir(name, parent); 218 if (IS_ERR(dir)) 219 return dir; 220 221 debugfs_create_ul("probability", mode, dir, &attr->probability); 222 debugfs_create_ul("interval", mode, dir, &attr->interval); 223 debugfs_create_atomic_t("times", mode, dir, &attr->times); 224 debugfs_create_atomic_t("space", mode, dir, &attr->space); 225 debugfs_create_ul("verbose", mode, dir, &attr->verbose); 226 debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir, 227 &attr->ratelimit_state.interval); 228 debugfs_create_u32("verbose_ratelimit_burst", mode, dir, 229 &attr->ratelimit_state.burst); 230 debugfs_create_bool("task-filter", mode, dir, &attr->task_filter); 231 232 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 233 debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir, 234 &attr->stacktrace_depth); 235 debugfs_create_xul("require-start", mode, dir, &attr->require_start); 236 debugfs_create_xul("require-end", mode, dir, &attr->require_end); 237 debugfs_create_xul("reject-start", mode, dir, &attr->reject_start); 238 debugfs_create_xul("reject-end", mode, dir, &attr->reject_end); 239 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 240 241 attr->dname = dget(dir); 242 return dir; 243 } 244 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr); 245 246 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 247 248 #ifdef CONFIG_FAULT_INJECTION_CONFIGFS 249 250 /* These configfs attribute utilities are copied from drivers/block/null_blk/main.c */ 251 252 static ssize_t fault_uint_attr_show(unsigned int val, char *page) 253 { 254 return snprintf(page, PAGE_SIZE, "%u\n", val); 255 } 256 257 static ssize_t fault_ulong_attr_show(unsigned long val, char *page) 258 { 259 return snprintf(page, PAGE_SIZE, "%lu\n", val); 260 } 261 262 static ssize_t fault_bool_attr_show(bool val, char *page) 263 { 264 return snprintf(page, PAGE_SIZE, "%u\n", val); 265 } 266 267 static ssize_t fault_atomic_t_attr_show(atomic_t val, char *page) 268 { 269 return snprintf(page, PAGE_SIZE, "%d\n", atomic_read(&val)); 270 } 271 272 static ssize_t fault_uint_attr_store(unsigned int *val, const char *page, size_t count) 273 { 274 unsigned int tmp; 275 int result; 276 277 result = kstrtouint(page, 0, &tmp); 278 if (result < 0) 279 return result; 280 281 *val = tmp; 282 return count; 283 } 284 285 static ssize_t fault_ulong_attr_store(unsigned long *val, const char *page, size_t count) 286 { 287 int result; 288 unsigned long tmp; 289 290 result = kstrtoul(page, 0, &tmp); 291 if (result < 0) 292 return result; 293 294 *val = tmp; 295 return count; 296 } 297 298 static ssize_t fault_bool_attr_store(bool *val, const char *page, size_t count) 299 { 300 bool tmp; 301 int result; 302 303 result = kstrtobool(page, &tmp); 304 if (result < 0) 305 return result; 306 307 *val = tmp; 308 return count; 309 } 310 311 static ssize_t fault_atomic_t_attr_store(atomic_t *val, const char *page, size_t count) 312 { 313 int tmp; 314 int result; 315 316 result = kstrtoint(page, 0, &tmp); 317 if (result < 0) 318 return result; 319 320 atomic_set(val, tmp); 321 return count; 322 } 323 324 #define CONFIGFS_ATTR_NAMED(_pfx, _name, _attr_name) \ 325 static struct configfs_attribute _pfx##attr_##_name = { \ 326 .ca_name = _attr_name, \ 327 .ca_mode = 0644, \ 328 .ca_owner = THIS_MODULE, \ 329 .show = _pfx##_name##_show, \ 330 .store = _pfx##_name##_store, \ 331 } 332 333 static struct fault_config *to_fault_config(struct config_item *item) 334 { 335 return container_of(to_config_group(item), struct fault_config, group); 336 } 337 338 #define FAULT_CONFIGFS_ATTR_NAMED(NAME, ATTR_NAME, MEMBER, TYPE) \ 339 static ssize_t fault_##NAME##_show(struct config_item *item, char *page) \ 340 { \ 341 return fault_##TYPE##_attr_show(to_fault_config(item)->attr.MEMBER, page); \ 342 } \ 343 static ssize_t fault_##NAME##_store(struct config_item *item, const char *page, size_t count) \ 344 { \ 345 struct fault_config *config = to_fault_config(item); \ 346 return fault_##TYPE##_attr_store(&config->attr.MEMBER, page, count); \ 347 } \ 348 CONFIGFS_ATTR_NAMED(fault_, NAME, ATTR_NAME) 349 350 #define FAULT_CONFIGFS_ATTR(NAME, TYPE) \ 351 FAULT_CONFIGFS_ATTR_NAMED(NAME, __stringify(NAME), NAME, TYPE) 352 353 FAULT_CONFIGFS_ATTR(probability, ulong); 354 FAULT_CONFIGFS_ATTR(interval, ulong); 355 FAULT_CONFIGFS_ATTR(times, atomic_t); 356 FAULT_CONFIGFS_ATTR(space, atomic_t); 357 FAULT_CONFIGFS_ATTR(verbose, ulong); 358 FAULT_CONFIGFS_ATTR_NAMED(ratelimit_interval, "verbose_ratelimit_interval_ms", 359 ratelimit_state.interval, uint); 360 FAULT_CONFIGFS_ATTR_NAMED(ratelimit_burst, "verbose_ratelimit_burst", 361 ratelimit_state.burst, uint); 362 FAULT_CONFIGFS_ATTR_NAMED(task_filter, "task-filter", task_filter, bool); 363 364 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 365 366 static ssize_t fault_stacktrace_depth_show(struct config_item *item, char *page) 367 { 368 return fault_ulong_attr_show(to_fault_config(item)->attr.stacktrace_depth, page); 369 } 370 371 static ssize_t fault_stacktrace_depth_store(struct config_item *item, const char *page, 372 size_t count) 373 { 374 int result; 375 unsigned long tmp; 376 377 result = kstrtoul(page, 0, &tmp); 378 if (result < 0) 379 return result; 380 381 to_fault_config(item)->attr.stacktrace_depth = 382 min_t(unsigned long, tmp, MAX_STACK_TRACE_DEPTH); 383 384 return count; 385 } 386 387 CONFIGFS_ATTR_NAMED(fault_, stacktrace_depth, "stacktrace-depth"); 388 389 static ssize_t fault_xul_attr_show(unsigned long val, char *page) 390 { 391 return snprintf(page, PAGE_SIZE, 392 sizeof(val) == sizeof(u32) ? "0x%08lx\n" : "0x%016lx\n", val); 393 } 394 395 static ssize_t fault_xul_attr_store(unsigned long *val, const char *page, size_t count) 396 { 397 return fault_ulong_attr_store(val, page, count); 398 } 399 400 FAULT_CONFIGFS_ATTR_NAMED(require_start, "require-start", require_start, xul); 401 FAULT_CONFIGFS_ATTR_NAMED(require_end, "require-end", require_end, xul); 402 FAULT_CONFIGFS_ATTR_NAMED(reject_start, "reject-start", reject_start, xul); 403 FAULT_CONFIGFS_ATTR_NAMED(reject_end, "reject-end", reject_end, xul); 404 405 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 406 407 static struct configfs_attribute *fault_config_attrs[] = { 408 &fault_attr_probability, 409 &fault_attr_interval, 410 &fault_attr_times, 411 &fault_attr_space, 412 &fault_attr_verbose, 413 &fault_attr_ratelimit_interval, 414 &fault_attr_ratelimit_burst, 415 &fault_attr_task_filter, 416 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 417 &fault_attr_stacktrace_depth, 418 &fault_attr_require_start, 419 &fault_attr_require_end, 420 &fault_attr_reject_start, 421 &fault_attr_reject_end, 422 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 423 NULL, 424 }; 425 426 static const struct config_item_type fault_config_type = { 427 .ct_attrs = fault_config_attrs, 428 .ct_owner = THIS_MODULE, 429 }; 430 431 void fault_config_init(struct fault_config *config, const char *name) 432 { 433 config_group_init_type_name(&config->group, name, &fault_config_type); 434 } 435 EXPORT_SYMBOL_GPL(fault_config_init); 436 437 #endif /* CONFIG_FAULT_INJECTION_CONFIGFS */ 438