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 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 && !WRITE_ONCE(current->fail_nth, fail_nth - 1)) 114 goto fail; 115 116 return false; 117 } 118 119 /* No need to check any other properties if the probability is 0 */ 120 if (attr->probability == 0) 121 return false; 122 123 if (attr->task_filter && !fail_task(attr, current)) 124 return false; 125 126 if (atomic_read(&attr->times) == 0) 127 return false; 128 129 if (atomic_read(&attr->space) > size) { 130 atomic_sub(size, &attr->space); 131 return false; 132 } 133 134 if (attr->interval > 1) { 135 attr->count++; 136 if (attr->count % attr->interval) 137 return false; 138 } 139 140 if (attr->probability <= prandom_u32() % 100) 141 return false; 142 143 if (!fail_stacktrace(attr)) 144 return false; 145 146 fail: 147 fail_dump(attr); 148 149 if (atomic_read(&attr->times) != -1) 150 atomic_dec_not_zero(&attr->times); 151 152 return true; 153 } 154 EXPORT_SYMBOL_GPL(should_fail); 155 156 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS 157 158 static int debugfs_ul_set(void *data, u64 val) 159 { 160 *(unsigned long *)data = val; 161 return 0; 162 } 163 164 static int debugfs_ul_get(void *data, u64 *val) 165 { 166 *val = *(unsigned long *)data; 167 return 0; 168 } 169 170 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); 171 172 static struct dentry *debugfs_create_ul(const char *name, umode_t mode, 173 struct dentry *parent, unsigned long *value) 174 { 175 return debugfs_create_file(name, mode, parent, value, &fops_ul); 176 } 177 178 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 179 180 static int debugfs_stacktrace_depth_set(void *data, u64 val) 181 { 182 *(unsigned long *)data = 183 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH); 184 185 return 0; 186 } 187 188 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get, 189 debugfs_stacktrace_depth_set, "%llu\n"); 190 191 static struct dentry *debugfs_create_stacktrace_depth( 192 const char *name, umode_t mode, 193 struct dentry *parent, unsigned long *value) 194 { 195 return debugfs_create_file(name, mode, parent, value, 196 &fops_stacktrace_depth); 197 } 198 199 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 200 201 struct dentry *fault_create_debugfs_attr(const char *name, 202 struct dentry *parent, struct fault_attr *attr) 203 { 204 umode_t mode = S_IFREG | S_IRUSR | S_IWUSR; 205 struct dentry *dir; 206 207 dir = debugfs_create_dir(name, parent); 208 if (!dir) 209 return ERR_PTR(-ENOMEM); 210 211 if (!debugfs_create_ul("probability", mode, dir, &attr->probability)) 212 goto fail; 213 if (!debugfs_create_ul("interval", mode, dir, &attr->interval)) 214 goto fail; 215 if (!debugfs_create_atomic_t("times", mode, dir, &attr->times)) 216 goto fail; 217 if (!debugfs_create_atomic_t("space", mode, dir, &attr->space)) 218 goto fail; 219 if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose)) 220 goto fail; 221 if (!debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir, 222 &attr->ratelimit_state.interval)) 223 goto fail; 224 if (!debugfs_create_u32("verbose_ratelimit_burst", mode, dir, 225 &attr->ratelimit_state.burst)) 226 goto fail; 227 if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter)) 228 goto fail; 229 230 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 231 232 if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir, 233 &attr->stacktrace_depth)) 234 goto fail; 235 if (!debugfs_create_ul("require-start", mode, dir, 236 &attr->require_start)) 237 goto fail; 238 if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end)) 239 goto fail; 240 if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start)) 241 goto fail; 242 if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end)) 243 goto fail; 244 245 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 246 247 attr->dname = dget(dir); 248 return dir; 249 fail: 250 debugfs_remove_recursive(dir); 251 252 return ERR_PTR(-ENOMEM); 253 } 254 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr); 255 256 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 257