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/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, &times) < 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 */