| 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
| 2 | /* audit_watch.c -- watching inodes |
| 3 | * |
| 4 | * Copyright 2003-2009 Red Hat, Inc. |
| 5 | * Copyright 2005 Hewlett-Packard Development Company, L.P. |
| 6 | * Copyright 2005 IBM Corporation |
| 7 | */ |
| 8 | |
| 9 | #include <linux/file.h> |
| 10 | #include <linux/kernel.h> |
| 11 | #include <linux/audit.h> |
| 12 | #include <linux/kthread.h> |
| 13 | #include <linux/mutex.h> |
| 14 | #include <linux/fs.h> |
| 15 | #include <linux/fsnotify_backend.h> |
| 16 | #include <linux/namei.h> |
| 17 | #include <linux/netlink.h> |
| 18 | #include <linux/refcount.h> |
| 19 | #include <linux/sched.h> |
| 20 | #include <linux/slab.h> |
| 21 | #include <linux/security.h> |
| 22 | #include "audit.h" |
| 23 | |
| 24 | /* |
| 25 | * Reference counting: |
| 26 | * |
| 27 | * audit_parent: lifetime is from audit_init_parent() to receipt of an FS_IGNORED |
| 28 | * event. Each audit_watch holds a reference to its associated parent. |
| 29 | * |
| 30 | * audit_watch: if added to lists, lifetime is from audit_init_watch() to |
| 31 | * audit_remove_watch(). Additionally, an audit_watch may exist |
| 32 | * temporarily to assist in searching existing filter data. Each |
| 33 | * audit_krule holds a reference to its associated watch. |
| 34 | */ |
| 35 | |
| 36 | struct audit_watch { |
| 37 | refcount_t count; /* reference count */ |
| 38 | dev_t dev; /* associated superblock device */ |
| 39 | char *path; /* insertion path */ |
| 40 | unsigned long ino; /* associated inode number */ |
| 41 | struct audit_parent *parent; /* associated parent */ |
| 42 | struct list_head wlist; /* entry in parent->watches list */ |
| 43 | struct list_head rules; /* anchor for krule->rlist */ |
| 44 | }; |
| 45 | |
| 46 | struct audit_parent { |
| 47 | struct list_head watches; /* anchor for audit_watch->wlist */ |
| 48 | struct fsnotify_mark mark; /* fsnotify mark on the inode */ |
| 49 | }; |
| 50 | |
| 51 | /* fsnotify handle. */ |
| 52 | static struct fsnotify_group *audit_watch_group; |
| 53 | |
| 54 | /* fsnotify events we care about. */ |
| 55 | #define AUDIT_FS_WATCH (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\ |
| 56 | FS_MOVE_SELF | FS_UNMOUNT) |
| 57 | |
| 58 | static void audit_free_parent(struct audit_parent *parent) |
| 59 | { |
| 60 | WARN_ON(!list_empty(&parent->watches)); |
| 61 | kfree(parent); |
| 62 | } |
| 63 | |
| 64 | static void audit_watch_free_mark(struct fsnotify_mark *entry) |
| 65 | { |
| 66 | struct audit_parent *parent; |
| 67 | |
| 68 | parent = container_of(entry, struct audit_parent, mark); |
| 69 | audit_free_parent(parent); |
| 70 | } |
| 71 | |
| 72 | static void audit_get_parent(struct audit_parent *parent) |
| 73 | { |
| 74 | if (likely(parent)) |
| 75 | fsnotify_get_mark(&parent->mark); |
| 76 | } |
| 77 | |
| 78 | static void audit_put_parent(struct audit_parent *parent) |
| 79 | { |
| 80 | if (likely(parent)) |
| 81 | fsnotify_put_mark(&parent->mark); |
| 82 | } |
| 83 | |
| 84 | /* |
| 85 | * Find and return the audit_parent on the given inode. If found a reference |
| 86 | * is taken on this parent. |
| 87 | */ |
| 88 | static inline struct audit_parent *audit_find_parent(struct inode *inode) |
| 89 | { |
| 90 | struct audit_parent *parent = NULL; |
| 91 | struct fsnotify_mark *entry; |
| 92 | |
| 93 | entry = fsnotify_find_mark(&inode->i_fsnotify_marks, audit_watch_group); |
| 94 | if (entry) |
| 95 | parent = container_of(entry, struct audit_parent, mark); |
| 96 | |
| 97 | return parent; |
| 98 | } |
| 99 | |
| 100 | void audit_get_watch(struct audit_watch *watch) |
| 101 | { |
| 102 | refcount_inc(&watch->count); |
| 103 | } |
| 104 | |
| 105 | void audit_put_watch(struct audit_watch *watch) |
| 106 | { |
| 107 | if (refcount_dec_and_test(&watch->count)) { |
| 108 | WARN_ON(watch->parent); |
| 109 | WARN_ON(!list_empty(&watch->rules)); |
| 110 | kfree(watch->path); |
| 111 | kfree(watch); |
| 112 | } |
| 113 | } |
| 114 | |
| 115 | static void audit_remove_watch(struct audit_watch *watch) |
| 116 | { |
| 117 | list_del(&watch->wlist); |
| 118 | audit_put_parent(watch->parent); |
| 119 | watch->parent = NULL; |
| 120 | audit_put_watch(watch); /* match initial get */ |
| 121 | } |
| 122 | |
| 123 | char *audit_watch_path(struct audit_watch *watch) |
| 124 | { |
| 125 | return watch->path; |
| 126 | } |
| 127 | |
| 128 | int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev_t dev) |
| 129 | { |
| 130 | return (watch->ino != AUDIT_INO_UNSET) && |
| 131 | (watch->ino == ino) && |
| 132 | (watch->dev == dev); |
| 133 | } |
| 134 | |
| 135 | /* Initialize a parent watch entry. */ |
| 136 | static struct audit_parent *audit_init_parent(const struct path *path) |
| 137 | { |
| 138 | struct inode *inode = d_backing_inode(path->dentry); |
| 139 | struct audit_parent *parent; |
| 140 | int ret; |
| 141 | |
| 142 | parent = kzalloc(sizeof(*parent), GFP_KERNEL); |
| 143 | if (unlikely(!parent)) |
| 144 | return ERR_PTR(-ENOMEM); |
| 145 | |
| 146 | INIT_LIST_HEAD(&parent->watches); |
| 147 | |
| 148 | fsnotify_init_mark(&parent->mark, audit_watch_group); |
| 149 | parent->mark.mask = AUDIT_FS_WATCH; |
| 150 | ret = fsnotify_add_inode_mark(&parent->mark, inode, 0); |
| 151 | if (ret < 0) { |
| 152 | audit_free_parent(parent); |
| 153 | return ERR_PTR(ret); |
| 154 | } |
| 155 | |
| 156 | return parent; |
| 157 | } |
| 158 | |
| 159 | /* Initialize a watch entry. */ |
| 160 | static struct audit_watch *audit_init_watch(char *path) |
| 161 | { |
| 162 | struct audit_watch *watch; |
| 163 | |
| 164 | watch = kzalloc(sizeof(*watch), GFP_KERNEL); |
| 165 | if (unlikely(!watch)) |
| 166 | return ERR_PTR(-ENOMEM); |
| 167 | |
| 168 | INIT_LIST_HEAD(&watch->rules); |
| 169 | refcount_set(&watch->count, 1); |
| 170 | watch->path = path; |
| 171 | watch->dev = AUDIT_DEV_UNSET; |
| 172 | watch->ino = AUDIT_INO_UNSET; |
| 173 | |
| 174 | return watch; |
| 175 | } |
| 176 | |
| 177 | /* Translate a watch string to kernel representation. */ |
| 178 | int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op) |
| 179 | { |
| 180 | struct audit_watch *watch; |
| 181 | |
| 182 | if (!audit_watch_group) |
| 183 | return -EOPNOTSUPP; |
| 184 | |
| 185 | if (path[0] != '/' || path[len-1] == '/' || |
| 186 | (krule->listnr != AUDIT_FILTER_EXIT && |
| 187 | krule->listnr != AUDIT_FILTER_URING_EXIT) || |
| 188 | op != Audit_equal || |
| 189 | krule->inode_f || krule->watch || krule->tree) |
| 190 | return -EINVAL; |
| 191 | |
| 192 | watch = audit_init_watch(path); |
| 193 | if (IS_ERR(watch)) |
| 194 | return PTR_ERR(watch); |
| 195 | |
| 196 | krule->watch = watch; |
| 197 | |
| 198 | return 0; |
| 199 | } |
| 200 | |
| 201 | /* Duplicate the given audit watch. The new watch's rules list is initialized |
| 202 | * to an empty list and wlist is undefined. */ |
| 203 | static struct audit_watch *audit_dupe_watch(struct audit_watch *old) |
| 204 | { |
| 205 | char *path; |
| 206 | struct audit_watch *new; |
| 207 | |
| 208 | path = kstrdup(old->path, GFP_KERNEL); |
| 209 | if (unlikely(!path)) |
| 210 | return ERR_PTR(-ENOMEM); |
| 211 | |
| 212 | new = audit_init_watch(path); |
| 213 | if (IS_ERR(new)) { |
| 214 | kfree(path); |
| 215 | goto out; |
| 216 | } |
| 217 | |
| 218 | new->dev = old->dev; |
| 219 | new->ino = old->ino; |
| 220 | audit_get_parent(old->parent); |
| 221 | new->parent = old->parent; |
| 222 | |
| 223 | out: |
| 224 | return new; |
| 225 | } |
| 226 | |
| 227 | static void audit_watch_log_rule_change(struct audit_krule *r, struct audit_watch *w, char *op) |
| 228 | { |
| 229 | struct audit_buffer *ab; |
| 230 | |
| 231 | if (!audit_enabled) |
| 232 | return; |
| 233 | ab = audit_log_start(audit_context(), GFP_NOFS, AUDIT_CONFIG_CHANGE); |
| 234 | if (!ab) |
| 235 | return; |
| 236 | audit_log_session_info(ab); |
| 237 | audit_log_format(ab, "op=%s path=", op); |
| 238 | audit_log_untrustedstring(ab, w->path); |
| 239 | audit_log_key(ab, r->filterkey); |
| 240 | audit_log_format(ab, " list=%d res=1", r->listnr); |
| 241 | audit_log_end(ab); |
| 242 | } |
| 243 | |
| 244 | /* Update inode info in audit rules based on filesystem event. */ |
| 245 | static void audit_update_watch(struct audit_parent *parent, |
| 246 | const struct qstr *dname, dev_t dev, |
| 247 | unsigned long ino, unsigned invalidating) |
| 248 | { |
| 249 | struct audit_watch *owatch, *nwatch, *nextw; |
| 250 | struct audit_krule *r, *nextr; |
| 251 | struct audit_entry *oentry, *nentry; |
| 252 | |
| 253 | mutex_lock(&audit_filter_mutex); |
| 254 | /* Run all of the watches on this parent looking for the one that |
| 255 | * matches the given dname */ |
| 256 | list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) { |
| 257 | if (audit_compare_dname_path(dname, owatch->path, |
| 258 | AUDIT_NAME_FULL)) |
| 259 | continue; |
| 260 | |
| 261 | /* If the update involves invalidating rules, do the inode-based |
| 262 | * filtering now, so we don't omit records. */ |
| 263 | if (invalidating && !audit_dummy_context()) |
| 264 | audit_filter_inodes(current, audit_context()); |
| 265 | |
| 266 | /* updating ino will likely change which audit_hash_list we |
| 267 | * are on so we need a new watch for the new list */ |
| 268 | nwatch = audit_dupe_watch(owatch); |
| 269 | if (IS_ERR(nwatch)) { |
| 270 | mutex_unlock(&audit_filter_mutex); |
| 271 | audit_panic("error updating watch, skipping"); |
| 272 | return; |
| 273 | } |
| 274 | nwatch->dev = dev; |
| 275 | nwatch->ino = ino; |
| 276 | |
| 277 | list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) { |
| 278 | |
| 279 | oentry = container_of(r, struct audit_entry, rule); |
| 280 | list_del(&oentry->rule.rlist); |
| 281 | list_del_rcu(&oentry->list); |
| 282 | |
| 283 | nentry = audit_dupe_rule(&oentry->rule); |
| 284 | if (IS_ERR(nentry)) { |
| 285 | list_del(&oentry->rule.list); |
| 286 | audit_panic("error updating watch, removing"); |
| 287 | } else { |
| 288 | int h = audit_hash_ino((u32)ino); |
| 289 | |
| 290 | /* |
| 291 | * nentry->rule.watch == oentry->rule.watch so |
| 292 | * we must drop that reference and set it to our |
| 293 | * new watch. |
| 294 | */ |
| 295 | audit_put_watch(nentry->rule.watch); |
| 296 | audit_get_watch(nwatch); |
| 297 | nentry->rule.watch = nwatch; |
| 298 | list_add(&nentry->rule.rlist, &nwatch->rules); |
| 299 | list_add_rcu(&nentry->list, &audit_inode_hash[h]); |
| 300 | list_replace(&oentry->rule.list, |
| 301 | &nentry->rule.list); |
| 302 | } |
| 303 | if (oentry->rule.exe) |
| 304 | audit_remove_mark(oentry->rule.exe); |
| 305 | |
| 306 | call_rcu(&oentry->rcu, audit_free_rule_rcu); |
| 307 | } |
| 308 | |
| 309 | audit_remove_watch(owatch); |
| 310 | goto add_watch_to_parent; /* event applies to a single watch */ |
| 311 | } |
| 312 | mutex_unlock(&audit_filter_mutex); |
| 313 | return; |
| 314 | |
| 315 | add_watch_to_parent: |
| 316 | list_add(&nwatch->wlist, &parent->watches); |
| 317 | mutex_unlock(&audit_filter_mutex); |
| 318 | return; |
| 319 | } |
| 320 | |
| 321 | /* Remove all watches & rules associated with a parent that is going away. */ |
| 322 | static void audit_remove_parent_watches(struct audit_parent *parent) |
| 323 | { |
| 324 | struct audit_watch *w, *nextw; |
| 325 | struct audit_krule *r, *nextr; |
| 326 | struct audit_entry *e; |
| 327 | |
| 328 | mutex_lock(&audit_filter_mutex); |
| 329 | list_for_each_entry_safe(w, nextw, &parent->watches, wlist) { |
| 330 | list_for_each_entry_safe(r, nextr, &w->rules, rlist) { |
| 331 | e = container_of(r, struct audit_entry, rule); |
| 332 | audit_watch_log_rule_change(r, w, "remove_rule"); |
| 333 | if (e->rule.exe) |
| 334 | audit_remove_mark(e->rule.exe); |
| 335 | list_del(&r->rlist); |
| 336 | list_del(&r->list); |
| 337 | list_del_rcu(&e->list); |
| 338 | call_rcu(&e->rcu, audit_free_rule_rcu); |
| 339 | } |
| 340 | audit_remove_watch(w); |
| 341 | } |
| 342 | mutex_unlock(&audit_filter_mutex); |
| 343 | |
| 344 | fsnotify_destroy_mark(&parent->mark, audit_watch_group); |
| 345 | } |
| 346 | |
| 347 | /* Get path information necessary for adding watches. */ |
| 348 | static int audit_get_nd(struct audit_watch *watch, struct path *parent) |
| 349 | { |
| 350 | struct dentry *d = kern_path_locked(watch->path, parent); |
| 351 | if (IS_ERR(d)) |
| 352 | return PTR_ERR(d); |
| 353 | if (d_is_positive(d)) { |
| 354 | /* update watch filter fields */ |
| 355 | watch->dev = d->d_sb->s_dev; |
| 356 | watch->ino = d_backing_inode(d)->i_ino; |
| 357 | } |
| 358 | inode_unlock(d_backing_inode(parent->dentry)); |
| 359 | dput(d); |
| 360 | return 0; |
| 361 | } |
| 362 | |
| 363 | /* Associate the given rule with an existing parent. |
| 364 | * Caller must hold audit_filter_mutex. */ |
| 365 | static void audit_add_to_parent(struct audit_krule *krule, |
| 366 | struct audit_parent *parent) |
| 367 | { |
| 368 | struct audit_watch *w, *watch = krule->watch; |
| 369 | int watch_found = 0; |
| 370 | |
| 371 | BUG_ON(!mutex_is_locked(&audit_filter_mutex)); |
| 372 | |
| 373 | list_for_each_entry(w, &parent->watches, wlist) { |
| 374 | if (strcmp(watch->path, w->path)) |
| 375 | continue; |
| 376 | |
| 377 | watch_found = 1; |
| 378 | |
| 379 | /* put krule's ref to temporary watch */ |
| 380 | audit_put_watch(watch); |
| 381 | |
| 382 | audit_get_watch(w); |
| 383 | krule->watch = watch = w; |
| 384 | |
| 385 | audit_put_parent(parent); |
| 386 | break; |
| 387 | } |
| 388 | |
| 389 | if (!watch_found) { |
| 390 | watch->parent = parent; |
| 391 | |
| 392 | audit_get_watch(watch); |
| 393 | list_add(&watch->wlist, &parent->watches); |
| 394 | } |
| 395 | list_add(&krule->rlist, &watch->rules); |
| 396 | } |
| 397 | |
| 398 | /* Find a matching watch entry, or add this one. |
| 399 | * Caller must hold audit_filter_mutex. */ |
| 400 | int audit_add_watch(struct audit_krule *krule, struct list_head **list) |
| 401 | { |
| 402 | struct audit_watch *watch = krule->watch; |
| 403 | struct audit_parent *parent; |
| 404 | struct path parent_path; |
| 405 | int h, ret = 0; |
| 406 | |
| 407 | /* |
| 408 | * When we will be calling audit_add_to_parent, krule->watch might have |
| 409 | * been updated and watch might have been freed. |
| 410 | * So we need to keep a reference of watch. |
| 411 | */ |
| 412 | audit_get_watch(watch); |
| 413 | |
| 414 | mutex_unlock(&audit_filter_mutex); |
| 415 | |
| 416 | /* Avoid calling path_lookup under audit_filter_mutex. */ |
| 417 | ret = audit_get_nd(watch, &parent_path); |
| 418 | |
| 419 | /* caller expects mutex locked */ |
| 420 | mutex_lock(&audit_filter_mutex); |
| 421 | |
| 422 | if (ret) { |
| 423 | audit_put_watch(watch); |
| 424 | return ret; |
| 425 | } |
| 426 | |
| 427 | /* either find an old parent or attach a new one */ |
| 428 | parent = audit_find_parent(d_backing_inode(parent_path.dentry)); |
| 429 | if (!parent) { |
| 430 | parent = audit_init_parent(&parent_path); |
| 431 | if (IS_ERR(parent)) { |
| 432 | ret = PTR_ERR(parent); |
| 433 | goto error; |
| 434 | } |
| 435 | } |
| 436 | |
| 437 | audit_add_to_parent(krule, parent); |
| 438 | |
| 439 | h = audit_hash_ino((u32)watch->ino); |
| 440 | *list = &audit_inode_hash[h]; |
| 441 | error: |
| 442 | path_put(&parent_path); |
| 443 | audit_put_watch(watch); |
| 444 | return ret; |
| 445 | } |
| 446 | |
| 447 | void audit_remove_watch_rule(struct audit_krule *krule) |
| 448 | { |
| 449 | struct audit_watch *watch = krule->watch; |
| 450 | struct audit_parent *parent = watch->parent; |
| 451 | |
| 452 | list_del(&krule->rlist); |
| 453 | |
| 454 | if (list_empty(&watch->rules)) { |
| 455 | /* |
| 456 | * audit_remove_watch() drops our reference to 'parent' which |
| 457 | * can get freed. Grab our own reference to be safe. |
| 458 | */ |
| 459 | audit_get_parent(parent); |
| 460 | audit_remove_watch(watch); |
| 461 | if (list_empty(&parent->watches)) |
| 462 | fsnotify_destroy_mark(&parent->mark, audit_watch_group); |
| 463 | audit_put_parent(parent); |
| 464 | } |
| 465 | } |
| 466 | |
| 467 | /* Update watch data in audit rules based on fsnotify events. */ |
| 468 | static int audit_watch_handle_event(struct fsnotify_mark *inode_mark, u32 mask, |
| 469 | struct inode *inode, struct inode *dir, |
| 470 | const struct qstr *dname, u32 cookie) |
| 471 | { |
| 472 | struct audit_parent *parent; |
| 473 | |
| 474 | parent = container_of(inode_mark, struct audit_parent, mark); |
| 475 | |
| 476 | if (WARN_ON_ONCE(inode_mark->group != audit_watch_group)) |
| 477 | return 0; |
| 478 | |
| 479 | if (mask & (FS_CREATE|FS_MOVED_TO) && inode) |
| 480 | audit_update_watch(parent, dname, inode->i_sb->s_dev, inode->i_ino, 0); |
| 481 | else if (mask & (FS_DELETE|FS_MOVED_FROM)) |
| 482 | audit_update_watch(parent, dname, AUDIT_DEV_UNSET, AUDIT_INO_UNSET, 1); |
| 483 | else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF)) |
| 484 | audit_remove_parent_watches(parent); |
| 485 | |
| 486 | return 0; |
| 487 | } |
| 488 | |
| 489 | static const struct fsnotify_ops audit_watch_fsnotify_ops = { |
| 490 | .handle_inode_event = audit_watch_handle_event, |
| 491 | .free_mark = audit_watch_free_mark, |
| 492 | }; |
| 493 | |
| 494 | static int __init audit_watch_init(void) |
| 495 | { |
| 496 | audit_watch_group = fsnotify_alloc_group(&audit_watch_fsnotify_ops, 0); |
| 497 | if (IS_ERR(audit_watch_group)) { |
| 498 | audit_watch_group = NULL; |
| 499 | audit_panic("cannot create audit fsnotify group"); |
| 500 | } |
| 501 | return 0; |
| 502 | } |
| 503 | device_initcall(audit_watch_init); |
| 504 | |
| 505 | int audit_dupe_exe(struct audit_krule *new, struct audit_krule *old) |
| 506 | { |
| 507 | struct audit_fsnotify_mark *audit_mark; |
| 508 | char *pathname; |
| 509 | |
| 510 | pathname = kstrdup(audit_mark_path(old->exe), GFP_KERNEL); |
| 511 | if (!pathname) |
| 512 | return -ENOMEM; |
| 513 | |
| 514 | audit_mark = audit_alloc_mark(new, pathname, strlen(pathname)); |
| 515 | if (IS_ERR(audit_mark)) { |
| 516 | kfree(pathname); |
| 517 | return PTR_ERR(audit_mark); |
| 518 | } |
| 519 | new->exe = audit_mark; |
| 520 | |
| 521 | return 0; |
| 522 | } |
| 523 | |
| 524 | int audit_exe_compare(struct task_struct *tsk, struct audit_fsnotify_mark *mark) |
| 525 | { |
| 526 | struct file *exe_file; |
| 527 | unsigned long ino; |
| 528 | dev_t dev; |
| 529 | |
| 530 | /* only do exe filtering if we are recording @current events/records */ |
| 531 | if (tsk != current) |
| 532 | return 0; |
| 533 | |
| 534 | if (!current->mm) |
| 535 | return 0; |
| 536 | exe_file = get_mm_exe_file(current->mm); |
| 537 | if (!exe_file) |
| 538 | return 0; |
| 539 | ino = file_inode(exe_file)->i_ino; |
| 540 | dev = file_inode(exe_file)->i_sb->s_dev; |
| 541 | fput(exe_file); |
| 542 | |
| 543 | return audit_mark_compare(mark, ino, dev); |
| 544 | } |