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, ×) < 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 int depth = attr->stacktrace_depth; 69 unsigned long entries[MAX_STACK_TRACE_DEPTH]; 70 int n, nr_entries; 71 bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX); 72 73 if (depth == 0) 74 return found; 75 76 nr_entries = stack_trace_save(entries, depth, 1); 77 for (n = 0; n < nr_entries; n++) { 78 if (attr->reject_start <= entries[n] && 79 entries[n] < attr->reject_end) 80 return false; 81 if (attr->require_start <= entries[n] && 82 entries[n] < attr->require_end) 83 found = true; 84 } 85 return found; 86 } 87 88 #else 89 90 static inline bool fail_stacktrace(struct fault_attr *attr) 91 { 92 return true; 93 } 94 95 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 96 97 /* 98 * This code is stolen from failmalloc-1.0 99 * http://www.nongnu.org/failmalloc/ 100 */ 101 102 bool should_fail(struct fault_attr *attr, ssize_t size) 103 { 104 if (in_task()) { 105 unsigned int fail_nth = READ_ONCE(current->fail_nth); 106 107 if (fail_nth) { 108 if (!WRITE_ONCE(current->fail_nth, fail_nth - 1)) 109 goto fail; 110 111 return false; 112 } 113 } 114 115 /* No need to check any other properties if the probability is 0 */ 116 if (attr->probability == 0) 117 return false; 118 119 if (attr->task_filter && !fail_task(attr, current)) 120 return false; 121 122 if (atomic_read(&attr->times) == 0) 123 return false; 124 125 if (atomic_read(&attr->space) > size) { 126 atomic_sub(size, &attr->space); 127 return false; 128 } 129 130 if (attr->interval > 1) { 131 attr->count++; 132 if (attr->count % attr->interval) 133 return false; 134 } 135 136 if (attr->probability <= prandom_u32() % 100) 137 return false; 138 139 if (!fail_stacktrace(attr)) 140 return false; 141 142 fail: 143 fail_dump(attr); 144 145 if (atomic_read(&attr->times) != -1) 146 atomic_dec_not_zero(&attr->times); 147 148 return true; 149 } 150 EXPORT_SYMBOL_GPL(should_fail); 151 152 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS 153 154 static int debugfs_ul_set(void *data, u64 val) 155 { 156 *(unsigned long *)data = val; 157 return 0; 158 } 159 160 static int debugfs_ul_get(void *data, u64 *val) 161 { 162 *val = *(unsigned long *)data; 163 return 0; 164 } 165 166 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); 167 168 static struct dentry *debugfs_create_ul(const char *name, umode_t mode, 169 struct dentry *parent, unsigned long *value) 170 { 171 return debugfs_create_file(name, mode, parent, value, &fops_ul); 172 } 173 174 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 175 176 static int debugfs_stacktrace_depth_set(void *data, u64 val) 177 { 178 *(unsigned long *)data = 179 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH); 180 181 return 0; 182 } 183 184 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get, 185 debugfs_stacktrace_depth_set, "%llu\n"); 186 187 static struct dentry *debugfs_create_stacktrace_depth( 188 const char *name, umode_t mode, 189 struct dentry *parent, unsigned long *value) 190 { 191 return debugfs_create_file(name, mode, parent, value, 192 &fops_stacktrace_depth); 193 } 194 195 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 196 197 struct dentry *fault_create_debugfs_attr(const char *name, 198 struct dentry *parent, struct fault_attr *attr) 199 { 200 umode_t mode = S_IFREG | S_IRUSR | S_IWUSR; 201 struct dentry *dir; 202 203 dir = debugfs_create_dir(name, parent); 204 if (!dir) 205 return ERR_PTR(-ENOMEM); 206 207 if (!debugfs_create_ul("probability", mode, dir, &attr->probability)) 208 goto fail; 209 if (!debugfs_create_ul("interval", mode, dir, &attr->interval)) 210 goto fail; 211 if (!debugfs_create_atomic_t("times", mode, dir, &attr->times)) 212 goto fail; 213 if (!debugfs_create_atomic_t("space", mode, dir, &attr->space)) 214 goto fail; 215 if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose)) 216 goto fail; 217 if (!debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir, 218 &attr->ratelimit_state.interval)) 219 goto fail; 220 if (!debugfs_create_u32("verbose_ratelimit_burst", mode, dir, 221 &attr->ratelimit_state.burst)) 222 goto fail; 223 if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter)) 224 goto fail; 225 226 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 227 228 if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir, 229 &attr->stacktrace_depth)) 230 goto fail; 231 if (!debugfs_create_ul("require-start", mode, dir, 232 &attr->require_start)) 233 goto fail; 234 if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end)) 235 goto fail; 236 if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start)) 237 goto fail; 238 if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end)) 239 goto fail; 240 241 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 242 243 attr->dname = dget(dir); 244 return dir; 245 fail: 246 debugfs_remove_recursive(dir); 247 248 return ERR_PTR(-ENOMEM); 249 } 250 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr); 251 252 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 253