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/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 * setup_fault_attr() is a helper function for various __setup handlers, so it 17 * returns 0 on error, because that is what __setup handlers do. 18 */ 19 int setup_fault_attr(struct fault_attr *attr, char *str) 20 { 21 unsigned long probability; 22 unsigned long interval; 23 int times; 24 int space; 25 26 /* "<interval>,<probability>,<space>,<times>" */ 27 if (sscanf(str, "%lu,%lu,%d,%d", 28 &interval, &probability, &space, ×) < 4) { 29 printk(KERN_WARNING 30 "FAULT_INJECTION: failed to parse arguments\n"); 31 return 0; 32 } 33 34 attr->probability = probability; 35 attr->interval = interval; 36 atomic_set(&attr->times, times); 37 atomic_set(&attr->space, space); 38 39 return 1; 40 } 41 EXPORT_SYMBOL_GPL(setup_fault_attr); 42 43 static void fail_dump(struct fault_attr *attr) 44 { 45 if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) { 46 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n" 47 "name %pd, interval %lu, probability %lu, " 48 "space %d, times %d\n", attr->dname, 49 attr->interval, attr->probability, 50 atomic_read(&attr->space), 51 atomic_read(&attr->times)); 52 if (attr->verbose > 1) 53 dump_stack(); 54 } 55 } 56 57 #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0) 58 59 static bool fail_task(struct fault_attr *attr, struct task_struct *task) 60 { 61 return in_task() && task->make_it_fail; 62 } 63 64 #define MAX_STACK_TRACE_DEPTH 32 65 66 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 67 68 static bool fail_stacktrace(struct fault_attr *attr) 69 { 70 int depth = attr->stacktrace_depth; 71 unsigned long entries[MAX_STACK_TRACE_DEPTH]; 72 int n, nr_entries; 73 bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX); 74 75 if (depth == 0 || (found && !attr->reject_start && !attr->reject_end)) 76 return found; 77 78 nr_entries = stack_trace_save(entries, depth, 1); 79 for (n = 0; n < nr_entries; n++) { 80 if (attr->reject_start <= entries[n] && 81 entries[n] < attr->reject_end) 82 return false; 83 if (attr->require_start <= entries[n] && 84 entries[n] < attr->require_end) 85 found = true; 86 } 87 return found; 88 } 89 90 #else 91 92 static inline bool fail_stacktrace(struct fault_attr *attr) 93 { 94 return true; 95 } 96 97 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 98 99 /* 100 * This code is stolen from failmalloc-1.0 101 * http://www.nongnu.org/failmalloc/ 102 */ 103 104 bool should_fail_ex(struct fault_attr *attr, ssize_t size, int flags) 105 { 106 bool stack_checked = false; 107 108 if (in_task()) { 109 unsigned int fail_nth = READ_ONCE(current->fail_nth); 110 111 if (fail_nth) { 112 if (!fail_stacktrace(attr)) 113 return false; 114 115 stack_checked = true; 116 fail_nth--; 117 WRITE_ONCE(current->fail_nth, fail_nth); 118 if (!fail_nth) 119 goto fail; 120 121 return false; 122 } 123 } 124 125 /* No need to check any other properties if the probability is 0 */ 126 if (attr->probability == 0) 127 return false; 128 129 if (attr->task_filter && !fail_task(attr, current)) 130 return false; 131 132 if (atomic_read(&attr->times) == 0) 133 return false; 134 135 if (!stack_checked && !fail_stacktrace(attr)) 136 return false; 137 138 if (atomic_read(&attr->space) > size) { 139 atomic_sub(size, &attr->space); 140 return false; 141 } 142 143 if (attr->interval > 1) { 144 attr->count++; 145 if (attr->count % attr->interval) 146 return false; 147 } 148 149 if (attr->probability <= get_random_u32_below(100)) 150 return false; 151 152 fail: 153 if (!(flags & FAULT_NOWARN)) 154 fail_dump(attr); 155 156 if (atomic_read(&attr->times) != -1) 157 atomic_dec_not_zero(&attr->times); 158 159 return true; 160 } 161 162 bool should_fail(struct fault_attr *attr, ssize_t size) 163 { 164 return should_fail_ex(attr, size, 0); 165 } 166 EXPORT_SYMBOL_GPL(should_fail); 167 168 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS 169 170 static int debugfs_ul_set(void *data, u64 val) 171 { 172 *(unsigned long *)data = val; 173 return 0; 174 } 175 176 static int debugfs_ul_get(void *data, u64 *val) 177 { 178 *val = *(unsigned long *)data; 179 return 0; 180 } 181 182 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); 183 184 static void debugfs_create_ul(const char *name, umode_t mode, 185 struct dentry *parent, unsigned long *value) 186 { 187 debugfs_create_file(name, mode, parent, value, &fops_ul); 188 } 189 190 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 191 192 static int debugfs_stacktrace_depth_set(void *data, u64 val) 193 { 194 *(unsigned long *)data = 195 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH); 196 197 return 0; 198 } 199 200 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get, 201 debugfs_stacktrace_depth_set, "%llu\n"); 202 203 static void debugfs_create_stacktrace_depth(const char *name, umode_t mode, 204 struct dentry *parent, 205 unsigned long *value) 206 { 207 debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth); 208 } 209 210 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 211 212 struct dentry *fault_create_debugfs_attr(const char *name, 213 struct dentry *parent, struct fault_attr *attr) 214 { 215 umode_t mode = S_IFREG | S_IRUSR | S_IWUSR; 216 struct dentry *dir; 217 218 dir = debugfs_create_dir(name, parent); 219 if (IS_ERR(dir)) 220 return dir; 221 222 debugfs_create_ul("probability", mode, dir, &attr->probability); 223 debugfs_create_ul("interval", mode, dir, &attr->interval); 224 debugfs_create_atomic_t("times", mode, dir, &attr->times); 225 debugfs_create_atomic_t("space", mode, dir, &attr->space); 226 debugfs_create_ul("verbose", mode, dir, &attr->verbose); 227 debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir, 228 &attr->ratelimit_state.interval); 229 debugfs_create_u32("verbose_ratelimit_burst", mode, dir, 230 &attr->ratelimit_state.burst); 231 debugfs_create_bool("task-filter", mode, dir, &attr->task_filter); 232 233 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 234 debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir, 235 &attr->stacktrace_depth); 236 debugfs_create_xul("require-start", mode, dir, &attr->require_start); 237 debugfs_create_xul("require-end", mode, dir, &attr->require_end); 238 debugfs_create_xul("reject-start", mode, dir, &attr->reject_start); 239 debugfs_create_xul("reject-end", mode, dir, &attr->reject_end); 240 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 241 242 attr->dname = dget(dir); 243 return dir; 244 } 245 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr); 246 247 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 248 249 #ifdef CONFIG_FAULT_INJECTION_CONFIGFS 250 251 /* These configfs attribute utilities are copied from drivers/block/null_blk/main.c */ 252 253 static ssize_t fault_uint_attr_show(unsigned int val, char *page) 254 { 255 return snprintf(page, PAGE_SIZE, "%u\n", val); 256 } 257 258 static ssize_t fault_ulong_attr_show(unsigned long val, char *page) 259 { 260 return snprintf(page, PAGE_SIZE, "%lu\n", val); 261 } 262 263 static ssize_t fault_bool_attr_show(bool val, char *page) 264 { 265 return snprintf(page, PAGE_SIZE, "%u\n", val); 266 } 267 268 static ssize_t fault_atomic_t_attr_show(atomic_t val, char *page) 269 { 270 return snprintf(page, PAGE_SIZE, "%d\n", atomic_read(&val)); 271 } 272 273 static ssize_t fault_uint_attr_store(unsigned int *val, const char *page, size_t count) 274 { 275 unsigned int tmp; 276 int result; 277 278 result = kstrtouint(page, 0, &tmp); 279 if (result < 0) 280 return result; 281 282 *val = tmp; 283 return count; 284 } 285 286 static ssize_t fault_ulong_attr_store(unsigned long *val, const char *page, size_t count) 287 { 288 int result; 289 unsigned long tmp; 290 291 result = kstrtoul(page, 0, &tmp); 292 if (result < 0) 293 return result; 294 295 *val = tmp; 296 return count; 297 } 298 299 static ssize_t fault_bool_attr_store(bool *val, const char *page, size_t count) 300 { 301 bool tmp; 302 int result; 303 304 result = kstrtobool(page, &tmp); 305 if (result < 0) 306 return result; 307 308 *val = tmp; 309 return count; 310 } 311 312 static ssize_t fault_atomic_t_attr_store(atomic_t *val, const char *page, size_t count) 313 { 314 int tmp; 315 int result; 316 317 result = kstrtoint(page, 0, &tmp); 318 if (result < 0) 319 return result; 320 321 atomic_set(val, tmp); 322 return count; 323 } 324 325 #define CONFIGFS_ATTR_NAMED(_pfx, _name, _attr_name) \ 326 static struct configfs_attribute _pfx##attr_##_name = { \ 327 .ca_name = _attr_name, \ 328 .ca_mode = 0644, \ 329 .ca_owner = THIS_MODULE, \ 330 .show = _pfx##_name##_show, \ 331 .store = _pfx##_name##_store, \ 332 } 333 334 static struct fault_config *to_fault_config(struct config_item *item) 335 { 336 return container_of(to_config_group(item), struct fault_config, group); 337 } 338 339 #define FAULT_CONFIGFS_ATTR_NAMED(NAME, ATTR_NAME, MEMBER, TYPE) \ 340 static ssize_t fault_##NAME##_show(struct config_item *item, char *page) \ 341 { \ 342 return fault_##TYPE##_attr_show(to_fault_config(item)->attr.MEMBER, page); \ 343 } \ 344 static ssize_t fault_##NAME##_store(struct config_item *item, const char *page, size_t count) \ 345 { \ 346 struct fault_config *config = to_fault_config(item); \ 347 return fault_##TYPE##_attr_store(&config->attr.MEMBER, page, count); \ 348 } \ 349 CONFIGFS_ATTR_NAMED(fault_, NAME, ATTR_NAME) 350 351 #define FAULT_CONFIGFS_ATTR(NAME, TYPE) \ 352 FAULT_CONFIGFS_ATTR_NAMED(NAME, __stringify(NAME), NAME, TYPE) 353 354 FAULT_CONFIGFS_ATTR(probability, ulong); 355 FAULT_CONFIGFS_ATTR(interval, ulong); 356 FAULT_CONFIGFS_ATTR(times, atomic_t); 357 FAULT_CONFIGFS_ATTR(space, atomic_t); 358 FAULT_CONFIGFS_ATTR(verbose, ulong); 359 FAULT_CONFIGFS_ATTR_NAMED(ratelimit_interval, "verbose_ratelimit_interval_ms", 360 ratelimit_state.interval, uint); 361 FAULT_CONFIGFS_ATTR_NAMED(ratelimit_burst, "verbose_ratelimit_burst", 362 ratelimit_state.burst, uint); 363 FAULT_CONFIGFS_ATTR_NAMED(task_filter, "task-filter", task_filter, bool); 364 365 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 366 367 static ssize_t fault_stacktrace_depth_show(struct config_item *item, char *page) 368 { 369 return fault_ulong_attr_show(to_fault_config(item)->attr.stacktrace_depth, page); 370 } 371 372 static ssize_t fault_stacktrace_depth_store(struct config_item *item, const char *page, 373 size_t count) 374 { 375 int result; 376 unsigned long tmp; 377 378 result = kstrtoul(page, 0, &tmp); 379 if (result < 0) 380 return result; 381 382 to_fault_config(item)->attr.stacktrace_depth = 383 min_t(unsigned long, tmp, MAX_STACK_TRACE_DEPTH); 384 385 return count; 386 } 387 388 CONFIGFS_ATTR_NAMED(fault_, stacktrace_depth, "stacktrace-depth"); 389 390 static ssize_t fault_xul_attr_show(unsigned long val, char *page) 391 { 392 return snprintf(page, PAGE_SIZE, 393 sizeof(val) == sizeof(u32) ? "0x%08lx\n" : "0x%016lx\n", val); 394 } 395 396 static ssize_t fault_xul_attr_store(unsigned long *val, const char *page, size_t count) 397 { 398 return fault_ulong_attr_store(val, page, count); 399 } 400 401 FAULT_CONFIGFS_ATTR_NAMED(require_start, "require-start", require_start, xul); 402 FAULT_CONFIGFS_ATTR_NAMED(require_end, "require-end", require_end, xul); 403 FAULT_CONFIGFS_ATTR_NAMED(reject_start, "reject-start", reject_start, xul); 404 FAULT_CONFIGFS_ATTR_NAMED(reject_end, "reject-end", reject_end, xul); 405 406 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 407 408 static struct configfs_attribute *fault_config_attrs[] = { 409 &fault_attr_probability, 410 &fault_attr_interval, 411 &fault_attr_times, 412 &fault_attr_space, 413 &fault_attr_verbose, 414 &fault_attr_ratelimit_interval, 415 &fault_attr_ratelimit_burst, 416 &fault_attr_task_filter, 417 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 418 &fault_attr_stacktrace_depth, 419 &fault_attr_require_start, 420 &fault_attr_require_end, 421 &fault_attr_reject_start, 422 &fault_attr_reject_end, 423 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 424 NULL, 425 }; 426 427 static const struct config_item_type fault_config_type = { 428 .ct_attrs = fault_config_attrs, 429 .ct_owner = THIS_MODULE, 430 }; 431 432 void fault_config_init(struct fault_config *config, const char *name) 433 { 434 config_group_init_type_name(&config->group, name, &fault_config_type); 435 } 436 EXPORT_SYMBOL_GPL(fault_config_init); 437 438 #endif /* CONFIG_FAULT_INJECTION_CONFIGFS */ 439