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->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 58 static 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 67 static 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 91 static 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 */ 102 103 bool 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; 144 145 fail: 146 fail_dump(attr); 147 148 if (atomic_read(&attr->times) != -1) 149 atomic_dec_not_zero(&attr->times); 150 151 return true; 152 } 153 EXPORT_SYMBOL_GPL(should_fail); 154 155 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS 156 157 static int debugfs_ul_set(void *data, u64 val) 158 { 159 *(unsigned long *)data = val; 160 return 0; 161 } 162 163 static int debugfs_ul_get(void *data, u64 *val) 164 { 165 *val = *(unsigned long *)data; 166 return 0; 167 } 168 169 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); 170 171 static 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 178 179 static 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 } 186 187 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get, 188 debugfs_stacktrace_depth_set, "%llu\n"); 189 190 static 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 */ 198 199 struct 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 } 232 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr); 233 234 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 235