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)
 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(struct fault_attr *attr, ssize_t size)
104{
 
 
105	if (in_task()) {
106		unsigned int fail_nth = READ_ONCE(current->fail_nth);
107
108		if (fail_nth) {
 
 
 
 
109			fail_nth--;
110			WRITE_ONCE(current->fail_nth, fail_nth);
111			if (!fail_nth)
112				goto fail;
113
114			return false;
115		}
116	}
117
118	/* No need to check any other properties if the probability is 0 */
119	if (attr->probability == 0)
120		return false;
121
122	if (attr->task_filter && !fail_task(attr, current))
123		return false;
124
125	if (atomic_read(&attr->times) == 0)
126		return false;
127
 
 
 
128	if (atomic_read(&attr->space) > size) {
129		atomic_sub(size, &attr->space);
130		return false;
131	}
132
133	if (attr->interval > 1) {
134		attr->count++;
135		if (attr->count % attr->interval)
136			return false;
137	}
138
139	if (attr->probability <= prandom_u32() % 100)
140		return false;
141
142	if (!fail_stacktrace(attr))
143		return false;
144
145fail:
146	fail_dump(attr);
 
147
148	if (atomic_read(&attr->times) != -1)
149		atomic_dec_not_zero(&attr->times);
150
151	return true;
152}
 
 
 
 
 
153EXPORT_SYMBOL_GPL(should_fail);
154
155#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
156
157static int debugfs_ul_set(void *data, u64 val)
158{
159	*(unsigned long *)data = val;
160	return 0;
161}
162
163static int debugfs_ul_get(void *data, u64 *val)
164{
165	*val = *(unsigned long *)data;
166	return 0;
167}
168
169DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
170
171static void debugfs_create_ul(const char *name, umode_t mode,
172			      struct dentry *parent, unsigned long *value)
173{
174	debugfs_create_file(name, mode, parent, value, &fops_ul);
175}
176
177#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
178
179static int debugfs_stacktrace_depth_set(void *data, u64 val)
180{
181	*(unsigned long *)data =
182		min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
183
184	return 0;
185}
186
187DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
188			debugfs_stacktrace_depth_set, "%llu\n");
189
190static void debugfs_create_stacktrace_depth(const char *name, umode_t mode,
191					    struct dentry *parent,
192					    unsigned long *value)
193{
194	debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth);
195}
196
197#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
198
199struct dentry *fault_create_debugfs_attr(const char *name,
200			struct dentry *parent, struct fault_attr *attr)
201{
202	umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
203	struct dentry *dir;
204
205	dir = debugfs_create_dir(name, parent);
206	if (IS_ERR(dir))
207		return dir;
208
209	debugfs_create_ul("probability", mode, dir, &attr->probability);
210	debugfs_create_ul("interval", mode, dir, &attr->interval);
211	debugfs_create_atomic_t("times", mode, dir, &attr->times);
212	debugfs_create_atomic_t("space", mode, dir, &attr->space);
213	debugfs_create_ul("verbose", mode, dir, &attr->verbose);
214	debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
215			   &attr->ratelimit_state.interval);
216	debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
217			   &attr->ratelimit_state.burst);
218	debugfs_create_bool("task-filter", mode, dir, &attr->task_filter);
219
220#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
221	debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
222					&attr->stacktrace_depth);
223	debugfs_create_ul("require-start", mode, dir, &attr->require_start);
224	debugfs_create_ul("require-end", mode, dir, &attr->require_end);
225	debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
226	debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
227#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
228
229	attr->dname = dget(dir);
230	return dir;
231}
232EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
233
234#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */

  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 */