GNU Linux-libre 4.19.211-gnu1
[releases.git] / lib / fault-inject.c
1 #include <linux/kernel.h>
2 #include <linux/init.h>
3 #include <linux/random.h>
4 #include <linux/sched.h>
5 #include <linux/stat.h>
6 #include <linux/types.h>
7 #include <linux/fs.h>
8 #include <linux/export.h>
9 #include <linux/interrupt.h>
10 #include <linux/stacktrace.h>
11 #include <linux/fault-inject.h>
12
13 /*
14  * setup_fault_attr() is a helper function for various __setup handlers, so it
15  * returns 0 on error, because that is what __setup handlers do.
16  */
17 int setup_fault_attr(struct fault_attr *attr, char *str)
18 {
19         unsigned long probability;
20         unsigned long interval;
21         int times;
22         int space;
23
24         /* "<interval>,<probability>,<space>,<times>" */
25         if (sscanf(str, "%lu,%lu,%d,%d",
26                         &interval, &probability, &space, &times) < 4) {
27                 printk(KERN_WARNING
28                         "FAULT_INJECTION: failed to parse arguments\n");
29                 return 0;
30         }
31
32         attr->probability = probability;
33         attr->interval = interval;
34         atomic_set(&attr->times, times);
35         atomic_set(&attr->space, space);
36
37         return 1;
38 }
39 EXPORT_SYMBOL_GPL(setup_fault_attr);
40
41 static void fail_dump(struct fault_attr *attr)
42 {
43         if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) {
44                 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n"
45                        "name %pd, interval %lu, probability %lu, "
46                        "space %d, times %d\n", attr->dname,
47                        attr->interval, attr->probability,
48                        atomic_read(&attr->space),
49                        atomic_read(&attr->times));
50                 if (attr->verbose > 1)
51                         dump_stack();
52         }
53 }
54
55 #define atomic_dec_not_zero(v)          atomic_add_unless((v), -1, 0)
56
57 static bool fail_task(struct fault_attr *attr, struct task_struct *task)
58 {
59         return in_task() && task->make_it_fail;
60 }
61
62 #define MAX_STACK_TRACE_DEPTH 32
63
64 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
65
66 static bool fail_stacktrace(struct fault_attr *attr)
67 {
68         struct stack_trace trace;
69         int depth = attr->stacktrace_depth;
70         unsigned long entries[MAX_STACK_TRACE_DEPTH];
71         int n;
72         bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
73
74         if (depth == 0)
75                 return found;
76
77         trace.nr_entries = 0;
78         trace.entries = entries;
79         trace.max_entries = depth;
80         trace.skip = 1;
81
82         save_stack_trace(&trace);
83         for (n = 0; n < trace.nr_entries; n++) {
84                 if (attr->reject_start <= entries[n] &&
85                                entries[n] < attr->reject_end)
86                         return false;
87                 if (attr->require_start <= entries[n] &&
88                                entries[n] < attr->require_end)
89                         found = true;
90         }
91         return found;
92 }
93
94 #else
95
96 static inline bool fail_stacktrace(struct fault_attr *attr)
97 {
98         return true;
99 }
100
101 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
102
103 /*
104  * This code is stolen from failmalloc-1.0
105  * http://www.nongnu.org/failmalloc/
106  */
107
108 bool should_fail(struct fault_attr *attr, ssize_t size)
109 {
110         if (in_task()) {
111                 unsigned int fail_nth = READ_ONCE(current->fail_nth);
112
113                 if (fail_nth) {
114                         if (!WRITE_ONCE(current->fail_nth, fail_nth - 1))
115                                 goto fail;
116
117                         return false;
118                 }
119         }
120
121         /* No need to check any other properties if the probability is 0 */
122         if (attr->probability == 0)
123                 return false;
124
125         if (attr->task_filter && !fail_task(attr, current))
126                 return false;
127
128         if (atomic_read(&attr->times) == 0)
129                 return false;
130
131         if (atomic_read(&attr->space) > size) {
132                 atomic_sub(size, &attr->space);
133                 return false;
134         }
135
136         if (attr->interval > 1) {
137                 attr->count++;
138                 if (attr->count % attr->interval)
139                         return false;
140         }
141
142         if (attr->probability <= prandom_u32() % 100)
143                 return false;
144
145         if (!fail_stacktrace(attr))
146                 return false;
147
148 fail:
149         fail_dump(attr);
150
151         if (atomic_read(&attr->times) != -1)
152                 atomic_dec_not_zero(&attr->times);
153
154         return true;
155 }
156 EXPORT_SYMBOL_GPL(should_fail);
157
158 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
159
160 static int debugfs_ul_set(void *data, u64 val)
161 {
162         *(unsigned long *)data = val;
163         return 0;
164 }
165
166 static int debugfs_ul_get(void *data, u64 *val)
167 {
168         *val = *(unsigned long *)data;
169         return 0;
170 }
171
172 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
173
174 static struct dentry *debugfs_create_ul(const char *name, umode_t mode,
175                                 struct dentry *parent, unsigned long *value)
176 {
177         return debugfs_create_file(name, mode, parent, value, &fops_ul);
178 }
179
180 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
181
182 static int debugfs_stacktrace_depth_set(void *data, u64 val)
183 {
184         *(unsigned long *)data =
185                 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
186
187         return 0;
188 }
189
190 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
191                         debugfs_stacktrace_depth_set, "%llu\n");
192
193 static struct dentry *debugfs_create_stacktrace_depth(
194         const char *name, umode_t mode,
195         struct dentry *parent, unsigned long *value)
196 {
197         return debugfs_create_file(name, mode, parent, value,
198                                    &fops_stacktrace_depth);
199 }
200
201 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
202
203 struct dentry *fault_create_debugfs_attr(const char *name,
204                         struct dentry *parent, struct fault_attr *attr)
205 {
206         umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
207         struct dentry *dir;
208
209         dir = debugfs_create_dir(name, parent);
210         if (!dir)
211                 return ERR_PTR(-ENOMEM);
212
213         if (!debugfs_create_ul("probability", mode, dir, &attr->probability))
214                 goto fail;
215         if (!debugfs_create_ul("interval", mode, dir, &attr->interval))
216                 goto fail;
217         if (!debugfs_create_atomic_t("times", mode, dir, &attr->times))
218                 goto fail;
219         if (!debugfs_create_atomic_t("space", mode, dir, &attr->space))
220                 goto fail;
221         if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose))
222                 goto fail;
223         if (!debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
224                                 &attr->ratelimit_state.interval))
225                 goto fail;
226         if (!debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
227                                 &attr->ratelimit_state.burst))
228                 goto fail;
229         if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter))
230                 goto fail;
231
232 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
233
234         if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
235                                 &attr->stacktrace_depth))
236                 goto fail;
237         if (!debugfs_create_ul("require-start", mode, dir,
238                                 &attr->require_start))
239                 goto fail;
240         if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end))
241                 goto fail;
242         if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start))
243                 goto fail;
244         if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end))
245                 goto fail;
246
247 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
248
249         attr->dname = dget(dir);
250         return dir;
251 fail:
252         debugfs_remove_recursive(dir);
253
254         return ERR_PTR(-ENOMEM);
255 }
256 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
257
258 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */