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 */ 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, ×) < 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 42 static void fail_dump(struct fault_attr *attr) 43 { 44 if (attr->no_warn) 45 return; 46 47 if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) { 48 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n" 49 "name %pd, interval %lu, probability %lu, " 50 "space %d, times %d\n", attr->dname, 51 attr->interval, attr->probability, 52 atomic_read(&attr->space), 53 atomic_read(&attr->times)); 54 if (attr->verbose > 1) 55 dump_stack(); 56 } 57 } 58 59 #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0) 60 61 static bool fail_task(struct fault_attr *attr, struct task_struct *task) 62 { 63 return in_task() && task->make_it_fail; 64 } 65 66 #define MAX_STACK_TRACE_DEPTH 32 67 68 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 69 70 static bool fail_stacktrace(struct fault_attr *attr) 71 { 72 int depth = attr->stacktrace_depth; 73 unsigned long entries[MAX_STACK_TRACE_DEPTH]; 74 int n, nr_entries; 75 bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX); 76 77 if (depth == 0) 78 return found; 79 80 nr_entries = stack_trace_save(entries, depth, 1); 81 for (n = 0; n < nr_entries; n++) { 82 if (attr->reject_start <= entries[n] && 83 entries[n] < attr->reject_end) 84 return false; 85 if (attr->require_start <= entries[n] && 86 entries[n] < attr->require_end) 87 found = true; 88 } 89 return found; 90 } 91 92 #else 93 94 static inline bool fail_stacktrace(struct fault_attr *attr) 95 { 96 return true; 97 } 98 99 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 100 101 /* 102 * This code is stolen from failmalloc-1.0 103 * http://www.nongnu.org/failmalloc/ 104 */ 105 106 bool should_fail(struct fault_attr *attr, ssize_t size) 107 { 108 if (in_task()) { 109 unsigned int fail_nth = READ_ONCE(current->fail_nth); 110 111 if (fail_nth) { 112 fail_nth--; 113 WRITE_ONCE(current->fail_nth, fail_nth); 114 if (!fail_nth) 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 void debugfs_create_ul(const char *name, umode_t mode, 175 struct dentry *parent, unsigned long *value) 176 { 177 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 void debugfs_create_stacktrace_depth(const char *name, umode_t mode, 194 struct dentry *parent, 195 unsigned long *value) 196 { 197 debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth); 198 } 199 200 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 201 202 struct dentry *fault_create_debugfs_attr(const char *name, 203 struct dentry *parent, struct fault_attr *attr) 204 { 205 umode_t mode = S_IFREG | S_IRUSR | S_IWUSR; 206 struct dentry *dir; 207 208 dir = debugfs_create_dir(name, parent); 209 if (IS_ERR(dir)) 210 return dir; 211 212 debugfs_create_ul("probability", mode, dir, &attr->probability); 213 debugfs_create_ul("interval", mode, dir, &attr->interval); 214 debugfs_create_atomic_t("times", mode, dir, &attr->times); 215 debugfs_create_atomic_t("space", mode, dir, &attr->space); 216 debugfs_create_ul("verbose", mode, dir, &attr->verbose); 217 debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir, 218 &attr->ratelimit_state.interval); 219 debugfs_create_u32("verbose_ratelimit_burst", mode, dir, 220 &attr->ratelimit_state.burst); 221 debugfs_create_bool("task-filter", mode, dir, &attr->task_filter); 222 223 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 224 debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir, 225 &attr->stacktrace_depth); 226 debugfs_create_ul("require-start", mode, dir, &attr->require_start); 227 debugfs_create_ul("require-end", mode, dir, &attr->require_end); 228 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start); 229 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end); 230 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 231 232 attr->dname = dget(dir); 233 return dir; 234 } 235 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr); 236 237 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 238