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
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