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1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/kernel.h>
3#include <linux/init.h>
4#include <linux/prandom.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 * The should_fail() functions use prandom instead of the normal Linux RNG
17 * since they don't need cryptographically secure random numbers.
18 */
19static DEFINE_PER_CPU(struct rnd_state, fault_rnd_state);
20
21static u32 fault_prandom_u32_below_100(void)
22{
23 struct rnd_state *state;
24 u32 res;
25
26 state = &get_cpu_var(fault_rnd_state);
27 res = prandom_u32_state(state);
28 put_cpu_var(fault_rnd_state);
29
30 return res % 100;
31}
32
33/*
34 * setup_fault_attr() is a helper function for various __setup handlers, so it
35 * returns 0 on error, because that is what __setup handlers do.
36 */
37int setup_fault_attr(struct fault_attr *attr, char *str)
38{
39 unsigned long probability;
40 unsigned long interval;
41 int times;
42 int space;
43
44 /* "<interval>,<probability>,<space>,<times>" */
45 if (sscanf(str, "%lu,%lu,%d,%d",
46 &interval, &probability, &space, &times) < 4) {
47 printk(KERN_WARNING
48 "FAULT_INJECTION: failed to parse arguments\n");
49 return 0;
50 }
51
52 prandom_init_once(&fault_rnd_state);
53
54 attr->probability = probability;
55 attr->interval = interval;
56 atomic_set(&attr->times, times);
57 atomic_set(&attr->space, space);
58
59 return 1;
60}
61EXPORT_SYMBOL_GPL(setup_fault_attr);
62
63static void fail_dump(struct fault_attr *attr)
64{
65 if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) {
66 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n"
67 "name %pd, interval %lu, probability %lu, "
68 "space %d, times %d\n", attr->dname,
69 attr->interval, attr->probability,
70 atomic_read(&attr->space),
71 atomic_read(&attr->times));
72 if (attr->verbose > 1)
73 dump_stack();
74 }
75}
76
77#define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0)
78
79static bool fail_task(struct fault_attr *attr, struct task_struct *task)
80{
81 return in_task() && task->make_it_fail;
82}
83
84#define MAX_STACK_TRACE_DEPTH 32
85
86#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
87
88static bool fail_stacktrace(struct fault_attr *attr)
89{
90 int depth = attr->stacktrace_depth;
91 unsigned long entries[MAX_STACK_TRACE_DEPTH];
92 int n, nr_entries;
93 bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
94
95 if (depth == 0 || (found && !attr->reject_start && !attr->reject_end))
96 return found;
97
98 nr_entries = stack_trace_save(entries, depth, 1);
99 for (n = 0; n < nr_entries; n++) {
100 if (attr->reject_start <= entries[n] &&
101 entries[n] < attr->reject_end)
102 return false;
103 if (attr->require_start <= entries[n] &&
104 entries[n] < attr->require_end)
105 found = true;
106 }
107 return found;
108}
109
110#else
111
112static inline bool fail_stacktrace(struct fault_attr *attr)
113{
114 return true;
115}
116
117#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
118
119/*
120 * This code is stolen from failmalloc-1.0
121 * http://www.nongnu.org/failmalloc/
122 */
123
124bool should_fail_ex(struct fault_attr *attr, ssize_t size, int flags)
125{
126 bool stack_checked = false;
127
128 if (in_task()) {
129 unsigned int fail_nth = READ_ONCE(current->fail_nth);
130
131 if (fail_nth) {
132 if (!fail_stacktrace(attr))
133 return false;
134
135 stack_checked = true;
136 fail_nth--;
137 WRITE_ONCE(current->fail_nth, fail_nth);
138 if (!fail_nth)
139 goto fail;
140
141 return false;
142 }
143 }
144
145 /* No need to check any other properties if the probability is 0 */
146 if (attr->probability == 0)
147 return false;
148
149 if (attr->task_filter && !fail_task(attr, current))
150 return false;
151
152 if (atomic_read(&attr->times) == 0)
153 return false;
154
155 if (!stack_checked && !fail_stacktrace(attr))
156 return false;
157
158 if (atomic_read(&attr->space) > size) {
159 atomic_sub(size, &attr->space);
160 return false;
161 }
162
163 if (attr->interval > 1) {
164 attr->count++;
165 if (attr->count % attr->interval)
166 return false;
167 }
168
169 if (attr->probability <= fault_prandom_u32_below_100())
170 return false;
171
172fail:
173 if (!(flags & FAULT_NOWARN))
174 fail_dump(attr);
175
176 if (atomic_read(&attr->times) != -1)
177 atomic_dec_not_zero(&attr->times);
178
179 return true;
180}
181
182bool should_fail(struct fault_attr *attr, ssize_t size)
183{
184 return should_fail_ex(attr, size, 0);
185}
186EXPORT_SYMBOL_GPL(should_fail);
187
188#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
189
190static int debugfs_ul_set(void *data, u64 val)
191{
192 *(unsigned long *)data = val;
193 return 0;
194}
195
196static int debugfs_ul_get(void *data, u64 *val)
197{
198 *val = *(unsigned long *)data;
199 return 0;
200}
201
202DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
203
204static void debugfs_create_ul(const char *name, umode_t mode,
205 struct dentry *parent, unsigned long *value)
206{
207 debugfs_create_file(name, mode, parent, value, &fops_ul);
208}
209
210#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
211
212static int debugfs_stacktrace_depth_set(void *data, u64 val)
213{
214 *(unsigned long *)data =
215 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
216
217 return 0;
218}
219
220DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
221 debugfs_stacktrace_depth_set, "%llu\n");
222
223static void debugfs_create_stacktrace_depth(const char *name, umode_t mode,
224 struct dentry *parent,
225 unsigned long *value)
226{
227 debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth);
228}
229
230#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
231
232struct dentry *fault_create_debugfs_attr(const char *name,
233 struct dentry *parent, struct fault_attr *attr)
234{
235 umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
236 struct dentry *dir;
237
238 dir = debugfs_create_dir(name, parent);
239 if (IS_ERR(dir))
240 return dir;
241
242 prandom_init_once(&fault_rnd_state);
243
244 debugfs_create_ul("probability", mode, dir, &attr->probability);
245 debugfs_create_ul("interval", mode, dir, &attr->interval);
246 debugfs_create_atomic_t("times", mode, dir, &attr->times);
247 debugfs_create_atomic_t("space", mode, dir, &attr->space);
248 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
249 debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
250 &attr->ratelimit_state.interval);
251 debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
252 &attr->ratelimit_state.burst);
253 debugfs_create_bool("task-filter", mode, dir, &attr->task_filter);
254
255#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
256 debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
257 &attr->stacktrace_depth);
258 debugfs_create_xul("require-start", mode, dir, &attr->require_start);
259 debugfs_create_xul("require-end", mode, dir, &attr->require_end);
260 debugfs_create_xul("reject-start", mode, dir, &attr->reject_start);
261 debugfs_create_xul("reject-end", mode, dir, &attr->reject_end);
262#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
263
264 attr->dname = dget(dir);
265 return dir;
266}
267EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
268
269#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
270
271#ifdef CONFIG_FAULT_INJECTION_CONFIGFS
272
273/* These configfs attribute utilities are copied from drivers/block/null_blk/main.c */
274
275static ssize_t fault_uint_attr_show(unsigned int val, char *page)
276{
277 return snprintf(page, PAGE_SIZE, "%u\n", val);
278}
279
280static ssize_t fault_ulong_attr_show(unsigned long val, char *page)
281{
282 return snprintf(page, PAGE_SIZE, "%lu\n", val);
283}
284
285static ssize_t fault_bool_attr_show(bool val, char *page)
286{
287 return snprintf(page, PAGE_SIZE, "%u\n", val);
288}
289
290static ssize_t fault_atomic_t_attr_show(atomic_t val, char *page)
291{
292 return snprintf(page, PAGE_SIZE, "%d\n", atomic_read(&val));
293}
294
295static ssize_t fault_uint_attr_store(unsigned int *val, const char *page, size_t count)
296{
297 unsigned int tmp;
298 int result;
299
300 result = kstrtouint(page, 0, &tmp);
301 if (result < 0)
302 return result;
303
304 *val = tmp;
305 return count;
306}
307
308static ssize_t fault_ulong_attr_store(unsigned long *val, const char *page, size_t count)
309{
310 int result;
311 unsigned long tmp;
312
313 result = kstrtoul(page, 0, &tmp);
314 if (result < 0)
315 return result;
316
317 *val = tmp;
318 return count;
319}
320
321static ssize_t fault_bool_attr_store(bool *val, const char *page, size_t count)
322{
323 bool tmp;
324 int result;
325
326 result = kstrtobool(page, &tmp);
327 if (result < 0)
328 return result;
329
330 *val = tmp;
331 return count;
332}
333
334static ssize_t fault_atomic_t_attr_store(atomic_t *val, const char *page, size_t count)
335{
336 int tmp;
337 int result;
338
339 result = kstrtoint(page, 0, &tmp);
340 if (result < 0)
341 return result;
342
343 atomic_set(val, tmp);
344 return count;
345}
346
347#define CONFIGFS_ATTR_NAMED(_pfx, _name, _attr_name) \
348static struct configfs_attribute _pfx##attr_##_name = { \
349 .ca_name = _attr_name, \
350 .ca_mode = 0644, \
351 .ca_owner = THIS_MODULE, \
352 .show = _pfx##_name##_show, \
353 .store = _pfx##_name##_store, \
354}
355
356static struct fault_config *to_fault_config(struct config_item *item)
357{
358 return container_of(to_config_group(item), struct fault_config, group);
359}
360
361#define FAULT_CONFIGFS_ATTR_NAMED(NAME, ATTR_NAME, MEMBER, TYPE) \
362static ssize_t fault_##NAME##_show(struct config_item *item, char *page) \
363{ \
364 return fault_##TYPE##_attr_show(to_fault_config(item)->attr.MEMBER, page); \
365} \
366static ssize_t fault_##NAME##_store(struct config_item *item, const char *page, size_t count) \
367{ \
368 struct fault_config *config = to_fault_config(item); \
369 return fault_##TYPE##_attr_store(&config->attr.MEMBER, page, count); \
370} \
371CONFIGFS_ATTR_NAMED(fault_, NAME, ATTR_NAME)
372
373#define FAULT_CONFIGFS_ATTR(NAME, TYPE) \
374 FAULT_CONFIGFS_ATTR_NAMED(NAME, __stringify(NAME), NAME, TYPE)
375
376FAULT_CONFIGFS_ATTR(probability, ulong);
377FAULT_CONFIGFS_ATTR(interval, ulong);
378FAULT_CONFIGFS_ATTR(times, atomic_t);
379FAULT_CONFIGFS_ATTR(space, atomic_t);
380FAULT_CONFIGFS_ATTR(verbose, ulong);
381FAULT_CONFIGFS_ATTR_NAMED(ratelimit_interval, "verbose_ratelimit_interval_ms",
382 ratelimit_state.interval, uint);
383FAULT_CONFIGFS_ATTR_NAMED(ratelimit_burst, "verbose_ratelimit_burst",
384 ratelimit_state.burst, uint);
385FAULT_CONFIGFS_ATTR_NAMED(task_filter, "task-filter", task_filter, bool);
386
387#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
388
389static ssize_t fault_stacktrace_depth_show(struct config_item *item, char *page)
390{
391 return fault_ulong_attr_show(to_fault_config(item)->attr.stacktrace_depth, page);
392}
393
394static ssize_t fault_stacktrace_depth_store(struct config_item *item, const char *page,
395 size_t count)
396{
397 int result;
398 unsigned long tmp;
399
400 result = kstrtoul(page, 0, &tmp);
401 if (result < 0)
402 return result;
403
404 to_fault_config(item)->attr.stacktrace_depth =
405 min_t(unsigned long, tmp, MAX_STACK_TRACE_DEPTH);
406
407 return count;
408}
409
410CONFIGFS_ATTR_NAMED(fault_, stacktrace_depth, "stacktrace-depth");
411
412static ssize_t fault_xul_attr_show(unsigned long val, char *page)
413{
414 return snprintf(page, PAGE_SIZE,
415 sizeof(val) == sizeof(u32) ? "0x%08lx\n" : "0x%016lx\n", val);
416}
417
418static ssize_t fault_xul_attr_store(unsigned long *val, const char *page, size_t count)
419{
420 return fault_ulong_attr_store(val, page, count);
421}
422
423FAULT_CONFIGFS_ATTR_NAMED(require_start, "require-start", require_start, xul);
424FAULT_CONFIGFS_ATTR_NAMED(require_end, "require-end", require_end, xul);
425FAULT_CONFIGFS_ATTR_NAMED(reject_start, "reject-start", reject_start, xul);
426FAULT_CONFIGFS_ATTR_NAMED(reject_end, "reject-end", reject_end, xul);
427
428#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
429
430static struct configfs_attribute *fault_config_attrs[] = {
431 &fault_attr_probability,
432 &fault_attr_interval,
433 &fault_attr_times,
434 &fault_attr_space,
435 &fault_attr_verbose,
436 &fault_attr_ratelimit_interval,
437 &fault_attr_ratelimit_burst,
438 &fault_attr_task_filter,
439#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
440 &fault_attr_stacktrace_depth,
441 &fault_attr_require_start,
442 &fault_attr_require_end,
443 &fault_attr_reject_start,
444 &fault_attr_reject_end,
445#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
446 NULL,
447};
448
449static const struct config_item_type fault_config_type = {
450 .ct_attrs = fault_config_attrs,
451 .ct_owner = THIS_MODULE,
452};
453
454void fault_config_init(struct fault_config *config, const char *name)
455{
456 prandom_init_once(&fault_rnd_state);
457
458 config_group_init_type_name(&config->group, name, &fault_config_type);
459}
460EXPORT_SYMBOL_GPL(fault_config_init);
461
462#endif /* CONFIG_FAULT_INJECTION_CONFIGFS */