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 */
18int 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}
40EXPORT_SYMBOL_GPL(setup_fault_attr);
41
42static 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
58static 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
67static 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
91static 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
103bool 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
151fail:
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
161bool should_fail(struct fault_attr *attr, ssize_t size)
162{
163	return should_fail_ex(attr, size, 0);
164}
165EXPORT_SYMBOL_GPL(should_fail);
166
167#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
168
169static int debugfs_ul_set(void *data, u64 val)
170{
171	*(unsigned long *)data = val;
172	return 0;
173}
174
175static int debugfs_ul_get(void *data, u64 *val)
176{
177	*val = *(unsigned long *)data;
178	return 0;
179}
180
181DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
182
183static 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
191static 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
199DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
200			debugfs_stacktrace_depth_set, "%llu\n");
201
202static 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
211struct 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}
244EXPORT_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
252static ssize_t fault_uint_attr_show(unsigned int val, char *page)
253{
254	return snprintf(page, PAGE_SIZE, "%u\n", val);
255}
256
257static ssize_t fault_ulong_attr_show(unsigned long val, char *page)
258{
259	return snprintf(page, PAGE_SIZE, "%lu\n", val);
260}
261
262static ssize_t fault_bool_attr_show(bool val, char *page)
263{
264	return snprintf(page, PAGE_SIZE, "%u\n", val);
265}
266
267static 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
272static 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
285static 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
298static 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
311static 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)	\
325static 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
333static 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)				\
339static 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}												\
343static 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}												\
348CONFIGFS_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
353FAULT_CONFIGFS_ATTR(probability, ulong);
354FAULT_CONFIGFS_ATTR(interval, ulong);
355FAULT_CONFIGFS_ATTR(times, atomic_t);
356FAULT_CONFIGFS_ATTR(space, atomic_t);
357FAULT_CONFIGFS_ATTR(verbose, ulong);
358FAULT_CONFIGFS_ATTR_NAMED(ratelimit_interval, "verbose_ratelimit_interval_ms",
359		ratelimit_state.interval, uint);
360FAULT_CONFIGFS_ATTR_NAMED(ratelimit_burst, "verbose_ratelimit_burst",
361		ratelimit_state.burst, uint);
362FAULT_CONFIGFS_ATTR_NAMED(task_filter, "task-filter", task_filter, bool);
363
364#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
365
366static 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
371static 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
387CONFIGFS_ATTR_NAMED(fault_, stacktrace_depth, "stacktrace-depth");
388
389static 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
395static 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
400FAULT_CONFIGFS_ATTR_NAMED(require_start, "require-start", require_start, xul);
401FAULT_CONFIGFS_ATTR_NAMED(require_end, "require-end", require_end, xul);
402FAULT_CONFIGFS_ATTR_NAMED(reject_start, "reject-start", reject_start, xul);
403FAULT_CONFIGFS_ATTR_NAMED(reject_end, "reject-end", reject_end, xul);
404
405#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
406
407static 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
426static const struct config_item_type fault_config_type = {
427	.ct_attrs	= fault_config_attrs,
428	.ct_owner	= THIS_MODULE,
429};
430
431void fault_config_init(struct fault_config *config, const char *name)
432{
433	config_group_init_type_name(&config->group, name, &fault_config_type);
434}
435EXPORT_SYMBOL_GPL(fault_config_init);
436
437#endif /* CONFIG_FAULT_INJECTION_CONFIGFS */
438