lib/fault-inject.c

   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, &times) < 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 */