xref: /openbmc/linux/lib/fault-inject.c (revision 4668c7a2)
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  */
setup_fault_attr(struct fault_attr * attr,char * str)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 
fail_dump(struct fault_attr * attr)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 
fail_task(struct fault_attr * attr,struct task_struct * task)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 
fail_stacktrace(struct fault_attr * attr)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 
fail_stacktrace(struct fault_attr * attr)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 
should_fail_ex(struct fault_attr * attr,ssize_t size,int flags)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 
should_fail(struct fault_attr * attr,ssize_t size)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 
debugfs_ul_set(void * data,u64 val)169 static int debugfs_ul_set(void *data, u64 val)
170 {
171 	*(unsigned long *)data = val;
172 	return 0;
173 }
174 
debugfs_ul_get(void * data,u64 * val)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 
debugfs_create_ul(const char * name,umode_t mode,struct dentry * parent,unsigned long * value)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 
debugfs_stacktrace_depth_set(void * data,u64 val)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 
debugfs_create_stacktrace_depth(const char * name,umode_t mode,struct dentry * parent,unsigned long * value)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 
fault_create_debugfs_attr(const char * name,struct dentry * parent,struct fault_attr * attr)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 
fault_uint_attr_show(unsigned int val,char * page)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 
fault_ulong_attr_show(unsigned long val,char * page)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 
fault_bool_attr_show(bool val,char * page)262 static ssize_t fault_bool_attr_show(bool val, char *page)
263 {
264 	return snprintf(page, PAGE_SIZE, "%u\n", val);
265 }
266 
fault_atomic_t_attr_show(atomic_t val,char * page)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 
fault_uint_attr_store(unsigned int * val,const char * page,size_t count)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 
fault_ulong_attr_store(unsigned long * val,const char * page,size_t count)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 
fault_bool_attr_store(bool * val,const char * page,size_t count)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 
fault_atomic_t_attr_store(atomic_t * val,const char * page,size_t count)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 
to_fault_config(struct config_item * item)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 
fault_stacktrace_depth_show(struct config_item * item,char * page)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 
fault_stacktrace_depth_store(struct config_item * item,const char * page,size_t count)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 
fault_xul_attr_show(unsigned long val,char * page)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 
fault_xul_attr_store(unsigned long * val,const char * page,size_t count)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 
fault_config_init(struct fault_config * config,const char * name)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