| 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 */ |