Masami Hiramatsu | 4b1a29a | 2018-01-13 02:56:03 +0900 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
| 3 | * fail_function.c: Function-based error injection |
| 4 | */ |
| 5 | #include <linux/error-injection.h> |
| 6 | #include <linux/debugfs.h> |
| 7 | #include <linux/fault-inject.h> |
| 8 | #include <linux/kallsyms.h> |
| 9 | #include <linux/kprobes.h> |
| 10 | #include <linux/module.h> |
| 11 | #include <linux/mutex.h> |
| 12 | #include <linux/slab.h> |
| 13 | #include <linux/uaccess.h> |
| 14 | |
| 15 | static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs); |
| 16 | |
Masami Hiramatsu | b6b76dd | 2018-03-12 19:00:49 +0900 | [diff] [blame] | 17 | static void fei_post_handler(struct kprobe *kp, struct pt_regs *regs, |
| 18 | unsigned long flags) |
| 19 | { |
| 20 | /* |
| 21 | * A dummy post handler is required to prohibit optimizing, because |
| 22 | * jump optimization does not support execution path overriding. |
| 23 | */ |
| 24 | } |
| 25 | |
Masami Hiramatsu | 4b1a29a | 2018-01-13 02:56:03 +0900 | [diff] [blame] | 26 | struct fei_attr { |
| 27 | struct list_head list; |
| 28 | struct kprobe kp; |
| 29 | unsigned long retval; |
| 30 | }; |
| 31 | static DEFINE_MUTEX(fei_lock); |
| 32 | static LIST_HEAD(fei_attr_list); |
| 33 | static DECLARE_FAULT_ATTR(fei_fault_attr); |
| 34 | static struct dentry *fei_debugfs_dir; |
| 35 | |
| 36 | static unsigned long adjust_error_retval(unsigned long addr, unsigned long retv) |
| 37 | { |
| 38 | switch (get_injectable_error_type(addr)) { |
| 39 | case EI_ETYPE_NULL: |
| 40 | if (retv != 0) |
| 41 | return 0; |
| 42 | break; |
| 43 | case EI_ETYPE_ERRNO: |
| 44 | if (retv < (unsigned long)-MAX_ERRNO) |
| 45 | return (unsigned long)-EINVAL; |
| 46 | break; |
| 47 | case EI_ETYPE_ERRNO_NULL: |
| 48 | if (retv != 0 && retv < (unsigned long)-MAX_ERRNO) |
| 49 | return (unsigned long)-EINVAL; |
| 50 | break; |
| 51 | } |
| 52 | |
| 53 | return retv; |
| 54 | } |
| 55 | |
| 56 | static struct fei_attr *fei_attr_new(const char *sym, unsigned long addr) |
| 57 | { |
| 58 | struct fei_attr *attr; |
| 59 | |
| 60 | attr = kzalloc(sizeof(*attr), GFP_KERNEL); |
| 61 | if (attr) { |
| 62 | attr->kp.symbol_name = kstrdup(sym, GFP_KERNEL); |
| 63 | if (!attr->kp.symbol_name) { |
| 64 | kfree(attr); |
| 65 | return NULL; |
| 66 | } |
| 67 | attr->kp.pre_handler = fei_kprobe_handler; |
Masami Hiramatsu | b6b76dd | 2018-03-12 19:00:49 +0900 | [diff] [blame] | 68 | attr->kp.post_handler = fei_post_handler; |
Masami Hiramatsu | 4b1a29a | 2018-01-13 02:56:03 +0900 | [diff] [blame] | 69 | attr->retval = adjust_error_retval(addr, 0); |
| 70 | INIT_LIST_HEAD(&attr->list); |
| 71 | } |
| 72 | return attr; |
| 73 | } |
| 74 | |
| 75 | static void fei_attr_free(struct fei_attr *attr) |
| 76 | { |
| 77 | if (attr) { |
| 78 | kfree(attr->kp.symbol_name); |
| 79 | kfree(attr); |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | static struct fei_attr *fei_attr_lookup(const char *sym) |
| 84 | { |
| 85 | struct fei_attr *attr; |
| 86 | |
| 87 | list_for_each_entry(attr, &fei_attr_list, list) { |
| 88 | if (!strcmp(attr->kp.symbol_name, sym)) |
| 89 | return attr; |
| 90 | } |
| 91 | |
| 92 | return NULL; |
| 93 | } |
| 94 | |
| 95 | static bool fei_attr_is_valid(struct fei_attr *_attr) |
| 96 | { |
| 97 | struct fei_attr *attr; |
| 98 | |
| 99 | list_for_each_entry(attr, &fei_attr_list, list) { |
| 100 | if (attr == _attr) |
| 101 | return true; |
| 102 | } |
| 103 | |
| 104 | return false; |
| 105 | } |
| 106 | |
| 107 | static int fei_retval_set(void *data, u64 val) |
| 108 | { |
| 109 | struct fei_attr *attr = data; |
| 110 | unsigned long retv = (unsigned long)val; |
| 111 | int err = 0; |
| 112 | |
| 113 | mutex_lock(&fei_lock); |
| 114 | /* |
| 115 | * Since this operation can be done after retval file is removed, |
| 116 | * It is safer to check the attr is still valid before accessing |
| 117 | * its member. |
| 118 | */ |
| 119 | if (!fei_attr_is_valid(attr)) { |
| 120 | err = -ENOENT; |
| 121 | goto out; |
| 122 | } |
| 123 | |
| 124 | if (attr->kp.addr) { |
| 125 | if (adjust_error_retval((unsigned long)attr->kp.addr, |
| 126 | val) != retv) |
| 127 | err = -EINVAL; |
| 128 | } |
| 129 | if (!err) |
| 130 | attr->retval = val; |
| 131 | out: |
| 132 | mutex_unlock(&fei_lock); |
| 133 | |
| 134 | return err; |
| 135 | } |
| 136 | |
| 137 | static int fei_retval_get(void *data, u64 *val) |
| 138 | { |
| 139 | struct fei_attr *attr = data; |
| 140 | int err = 0; |
| 141 | |
| 142 | mutex_lock(&fei_lock); |
| 143 | /* Here we also validate @attr to ensure it still exists. */ |
| 144 | if (!fei_attr_is_valid(attr)) |
| 145 | err = -ENOENT; |
| 146 | else |
| 147 | *val = attr->retval; |
| 148 | mutex_unlock(&fei_lock); |
| 149 | |
| 150 | return err; |
| 151 | } |
| 152 | DEFINE_DEBUGFS_ATTRIBUTE(fei_retval_ops, fei_retval_get, fei_retval_set, |
| 153 | "%llx\n"); |
| 154 | |
Greg Kroah-Hartman | 4aa3b1f | 2019-01-22 16:21:44 +0100 | [diff] [blame] | 155 | static void fei_debugfs_add_attr(struct fei_attr *attr) |
Masami Hiramatsu | 4b1a29a | 2018-01-13 02:56:03 +0900 | [diff] [blame] | 156 | { |
| 157 | struct dentry *dir; |
| 158 | |
| 159 | dir = debugfs_create_dir(attr->kp.symbol_name, fei_debugfs_dir); |
Masami Hiramatsu | 4b1a29a | 2018-01-13 02:56:03 +0900 | [diff] [blame] | 160 | |
Greg Kroah-Hartman | 4aa3b1f | 2019-01-22 16:21:44 +0100 | [diff] [blame] | 161 | debugfs_create_file("retval", 0600, dir, attr, &fei_retval_ops); |
Masami Hiramatsu | 4b1a29a | 2018-01-13 02:56:03 +0900 | [diff] [blame] | 162 | } |
| 163 | |
| 164 | static void fei_debugfs_remove_attr(struct fei_attr *attr) |
| 165 | { |
| 166 | struct dentry *dir; |
| 167 | |
| 168 | dir = debugfs_lookup(attr->kp.symbol_name, fei_debugfs_dir); |
zhong jiang | ea6f650 | 2018-10-30 15:04:51 -0700 | [diff] [blame] | 169 | debugfs_remove_recursive(dir); |
Masami Hiramatsu | 4b1a29a | 2018-01-13 02:56:03 +0900 | [diff] [blame] | 170 | } |
| 171 | |
| 172 | static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs) |
| 173 | { |
| 174 | struct fei_attr *attr = container_of(kp, struct fei_attr, kp); |
| 175 | |
| 176 | if (should_fail(&fei_fault_attr, 1)) { |
| 177 | regs_set_return_value(regs, attr->retval); |
| 178 | override_function_with_return(regs); |
Masami Hiramatsu | 4b1a29a | 2018-01-13 02:56:03 +0900 | [diff] [blame] | 179 | return 1; |
| 180 | } |
| 181 | |
| 182 | return 0; |
| 183 | } |
| 184 | NOKPROBE_SYMBOL(fei_kprobe_handler) |
| 185 | |
| 186 | static void *fei_seq_start(struct seq_file *m, loff_t *pos) |
| 187 | { |
| 188 | mutex_lock(&fei_lock); |
| 189 | return seq_list_start(&fei_attr_list, *pos); |
| 190 | } |
| 191 | |
| 192 | static void fei_seq_stop(struct seq_file *m, void *v) |
| 193 | { |
| 194 | mutex_unlock(&fei_lock); |
| 195 | } |
| 196 | |
| 197 | static void *fei_seq_next(struct seq_file *m, void *v, loff_t *pos) |
| 198 | { |
| 199 | return seq_list_next(v, &fei_attr_list, pos); |
| 200 | } |
| 201 | |
| 202 | static int fei_seq_show(struct seq_file *m, void *v) |
| 203 | { |
| 204 | struct fei_attr *attr = list_entry(v, struct fei_attr, list); |
| 205 | |
Sakari Ailus | d75f773 | 2019-03-25 21:32:28 +0200 | [diff] [blame] | 206 | seq_printf(m, "%ps\n", attr->kp.addr); |
Masami Hiramatsu | 4b1a29a | 2018-01-13 02:56:03 +0900 | [diff] [blame] | 207 | return 0; |
| 208 | } |
| 209 | |
| 210 | static const struct seq_operations fei_seq_ops = { |
| 211 | .start = fei_seq_start, |
| 212 | .next = fei_seq_next, |
| 213 | .stop = fei_seq_stop, |
| 214 | .show = fei_seq_show, |
| 215 | }; |
| 216 | |
| 217 | static int fei_open(struct inode *inode, struct file *file) |
| 218 | { |
| 219 | return seq_open(file, &fei_seq_ops); |
| 220 | } |
| 221 | |
| 222 | static void fei_attr_remove(struct fei_attr *attr) |
| 223 | { |
| 224 | fei_debugfs_remove_attr(attr); |
| 225 | unregister_kprobe(&attr->kp); |
| 226 | list_del(&attr->list); |
| 227 | fei_attr_free(attr); |
| 228 | } |
| 229 | |
| 230 | static void fei_attr_remove_all(void) |
| 231 | { |
| 232 | struct fei_attr *attr, *n; |
| 233 | |
| 234 | list_for_each_entry_safe(attr, n, &fei_attr_list, list) { |
| 235 | fei_attr_remove(attr); |
| 236 | } |
| 237 | } |
| 238 | |
| 239 | static ssize_t fei_write(struct file *file, const char __user *buffer, |
| 240 | size_t count, loff_t *ppos) |
| 241 | { |
| 242 | struct fei_attr *attr; |
| 243 | unsigned long addr; |
| 244 | char *buf, *sym; |
| 245 | int ret; |
| 246 | |
| 247 | /* cut off if it is too long */ |
| 248 | if (count > KSYM_NAME_LEN) |
| 249 | count = KSYM_NAME_LEN; |
Kees Cook | 6da2ec5 | 2018-06-12 13:55:00 -0700 | [diff] [blame] | 250 | buf = kmalloc(count + 1, GFP_KERNEL); |
Masami Hiramatsu | 4b1a29a | 2018-01-13 02:56:03 +0900 | [diff] [blame] | 251 | if (!buf) |
| 252 | return -ENOMEM; |
| 253 | |
| 254 | if (copy_from_user(buf, buffer, count)) { |
| 255 | ret = -EFAULT; |
| 256 | goto out; |
| 257 | } |
| 258 | buf[count] = '\0'; |
| 259 | sym = strstrip(buf); |
| 260 | |
| 261 | mutex_lock(&fei_lock); |
| 262 | |
| 263 | /* Writing just spaces will remove all injection points */ |
| 264 | if (sym[0] == '\0') { |
| 265 | fei_attr_remove_all(); |
| 266 | ret = count; |
| 267 | goto out; |
| 268 | } |
| 269 | /* Writing !function will remove one injection point */ |
| 270 | if (sym[0] == '!') { |
| 271 | attr = fei_attr_lookup(sym + 1); |
| 272 | if (!attr) { |
| 273 | ret = -ENOENT; |
| 274 | goto out; |
| 275 | } |
| 276 | fei_attr_remove(attr); |
| 277 | ret = count; |
| 278 | goto out; |
| 279 | } |
| 280 | |
| 281 | addr = kallsyms_lookup_name(sym); |
| 282 | if (!addr) { |
| 283 | ret = -EINVAL; |
| 284 | goto out; |
| 285 | } |
| 286 | if (!within_error_injection_list(addr)) { |
| 287 | ret = -ERANGE; |
| 288 | goto out; |
| 289 | } |
| 290 | if (fei_attr_lookup(sym)) { |
| 291 | ret = -EBUSY; |
| 292 | goto out; |
| 293 | } |
| 294 | attr = fei_attr_new(sym, addr); |
| 295 | if (!attr) { |
| 296 | ret = -ENOMEM; |
| 297 | goto out; |
| 298 | } |
| 299 | |
| 300 | ret = register_kprobe(&attr->kp); |
| 301 | if (!ret) |
Greg Kroah-Hartman | 4aa3b1f | 2019-01-22 16:21:44 +0100 | [diff] [blame] | 302 | fei_debugfs_add_attr(attr); |
Masami Hiramatsu | 4b1a29a | 2018-01-13 02:56:03 +0900 | [diff] [blame] | 303 | if (ret < 0) |
| 304 | fei_attr_remove(attr); |
| 305 | else { |
| 306 | list_add_tail(&attr->list, &fei_attr_list); |
| 307 | ret = count; |
| 308 | } |
| 309 | out: |
| 310 | kfree(buf); |
| 311 | mutex_unlock(&fei_lock); |
| 312 | return ret; |
| 313 | } |
| 314 | |
| 315 | static const struct file_operations fei_ops = { |
| 316 | .open = fei_open, |
| 317 | .read = seq_read, |
| 318 | .write = fei_write, |
| 319 | .llseek = seq_lseek, |
| 320 | .release = seq_release, |
| 321 | }; |
| 322 | |
| 323 | static int __init fei_debugfs_init(void) |
| 324 | { |
| 325 | struct dentry *dir; |
| 326 | |
| 327 | dir = fault_create_debugfs_attr("fail_function", NULL, |
| 328 | &fei_fault_attr); |
| 329 | if (IS_ERR(dir)) |
| 330 | return PTR_ERR(dir); |
| 331 | |
| 332 | /* injectable attribute is just a symlink of error_inject/list */ |
Greg Kroah-Hartman | 4aa3b1f | 2019-01-22 16:21:44 +0100 | [diff] [blame] | 333 | debugfs_create_symlink("injectable", dir, "../error_injection/list"); |
Masami Hiramatsu | 4b1a29a | 2018-01-13 02:56:03 +0900 | [diff] [blame] | 334 | |
Greg Kroah-Hartman | 4aa3b1f | 2019-01-22 16:21:44 +0100 | [diff] [blame] | 335 | debugfs_create_file("inject", 0600, dir, NULL, &fei_ops); |
Masami Hiramatsu | 4b1a29a | 2018-01-13 02:56:03 +0900 | [diff] [blame] | 336 | |
| 337 | fei_debugfs_dir = dir; |
| 338 | |
| 339 | return 0; |
Masami Hiramatsu | 4b1a29a | 2018-01-13 02:56:03 +0900 | [diff] [blame] | 340 | } |
| 341 | |
| 342 | late_initcall(fei_debugfs_init); |