1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/fanotify.h> 3 #include <linux/fcntl.h> 4 #include <linux/file.h> 5 #include <linux/fs.h> 6 #include <linux/anon_inodes.h> 7 #include <linux/fsnotify_backend.h> 8 #include <linux/init.h> 9 #include <linux/mount.h> 10 #include <linux/namei.h> 11 #include <linux/poll.h> 12 #include <linux/security.h> 13 #include <linux/syscalls.h> 14 #include <linux/slab.h> 15 #include <linux/types.h> 16 #include <linux/uaccess.h> 17 #include <linux/compat.h> 18 #include <linux/sched/signal.h> 19 #include <linux/memcontrol.h> 20 21 #include <asm/ioctls.h> 22 23 #include "../../mount.h" 24 #include "../fdinfo.h" 25 #include "fanotify.h" 26 27 #define FANOTIFY_DEFAULT_MAX_EVENTS 16384 28 #define FANOTIFY_DEFAULT_MAX_MARKS 8192 29 #define FANOTIFY_DEFAULT_MAX_LISTENERS 128 30 31 /* 32 * All flags that may be specified in parameter event_f_flags of fanotify_init. 33 * 34 * Internal and external open flags are stored together in field f_flags of 35 * struct file. Only external open flags shall be allowed in event_f_flags. 36 * Internal flags like FMODE_NONOTIFY, FMODE_EXEC, FMODE_NOCMTIME shall be 37 * excluded. 38 */ 39 #define FANOTIFY_INIT_ALL_EVENT_F_BITS ( \ 40 O_ACCMODE | O_APPEND | O_NONBLOCK | \ 41 __O_SYNC | O_DSYNC | O_CLOEXEC | \ 42 O_LARGEFILE | O_NOATIME ) 43 44 extern const struct fsnotify_ops fanotify_fsnotify_ops; 45 46 struct kmem_cache *fanotify_mark_cache __read_mostly; 47 struct kmem_cache *fanotify_event_cachep __read_mostly; 48 struct kmem_cache *fanotify_perm_event_cachep __read_mostly; 49 50 /* 51 * Get an fsnotify notification event if one exists and is small 52 * enough to fit in "count". Return an error pointer if the count 53 * is not large enough. 54 * 55 * Called with the group->notification_lock held. 56 */ 57 static struct fsnotify_event *get_one_event(struct fsnotify_group *group, 58 size_t count) 59 { 60 assert_spin_locked(&group->notification_lock); 61 62 pr_debug("%s: group=%p count=%zd\n", __func__, group, count); 63 64 if (fsnotify_notify_queue_is_empty(group)) 65 return NULL; 66 67 if (FAN_EVENT_METADATA_LEN > count) 68 return ERR_PTR(-EINVAL); 69 70 /* held the notification_lock the whole time, so this is the 71 * same event we peeked above */ 72 return fsnotify_remove_first_event(group); 73 } 74 75 static int create_fd(struct fsnotify_group *group, 76 struct fanotify_event_info *event, 77 struct file **file) 78 { 79 int client_fd; 80 struct file *new_file; 81 82 pr_debug("%s: group=%p event=%p\n", __func__, group, event); 83 84 client_fd = get_unused_fd_flags(group->fanotify_data.f_flags); 85 if (client_fd < 0) 86 return client_fd; 87 88 /* 89 * we need a new file handle for the userspace program so it can read even if it was 90 * originally opened O_WRONLY. 91 */ 92 /* it's possible this event was an overflow event. in that case dentry and mnt 93 * are NULL; That's fine, just don't call dentry open */ 94 if (event->path.dentry && event->path.mnt) 95 new_file = dentry_open(&event->path, 96 group->fanotify_data.f_flags | FMODE_NONOTIFY, 97 current_cred()); 98 else 99 new_file = ERR_PTR(-EOVERFLOW); 100 if (IS_ERR(new_file)) { 101 /* 102 * we still send an event even if we can't open the file. this 103 * can happen when say tasks are gone and we try to open their 104 * /proc files or we try to open a WRONLY file like in sysfs 105 * we just send the errno to userspace since there isn't much 106 * else we can do. 107 */ 108 put_unused_fd(client_fd); 109 client_fd = PTR_ERR(new_file); 110 } else { 111 *file = new_file; 112 } 113 114 return client_fd; 115 } 116 117 static int fill_event_metadata(struct fsnotify_group *group, 118 struct fanotify_event_metadata *metadata, 119 struct fsnotify_event *fsn_event, 120 struct file **file) 121 { 122 int ret = 0; 123 struct fanotify_event_info *event; 124 125 pr_debug("%s: group=%p metadata=%p event=%p\n", __func__, 126 group, metadata, fsn_event); 127 128 *file = NULL; 129 event = container_of(fsn_event, struct fanotify_event_info, fse); 130 metadata->event_len = FAN_EVENT_METADATA_LEN; 131 metadata->metadata_len = FAN_EVENT_METADATA_LEN; 132 metadata->vers = FANOTIFY_METADATA_VERSION; 133 metadata->reserved = 0; 134 metadata->mask = fsn_event->mask & FAN_ALL_OUTGOING_EVENTS; 135 metadata->pid = pid_vnr(event->tgid); 136 if (unlikely(fsn_event->mask & FAN_Q_OVERFLOW)) 137 metadata->fd = FAN_NOFD; 138 else { 139 metadata->fd = create_fd(group, event, file); 140 if (metadata->fd < 0) 141 ret = metadata->fd; 142 } 143 144 return ret; 145 } 146 147 static struct fanotify_perm_event_info *dequeue_event( 148 struct fsnotify_group *group, int fd) 149 { 150 struct fanotify_perm_event_info *event, *return_e = NULL; 151 152 spin_lock(&group->notification_lock); 153 list_for_each_entry(event, &group->fanotify_data.access_list, 154 fae.fse.list) { 155 if (event->fd != fd) 156 continue; 157 158 list_del_init(&event->fae.fse.list); 159 return_e = event; 160 break; 161 } 162 spin_unlock(&group->notification_lock); 163 164 pr_debug("%s: found return_re=%p\n", __func__, return_e); 165 166 return return_e; 167 } 168 169 static int process_access_response(struct fsnotify_group *group, 170 struct fanotify_response *response_struct) 171 { 172 struct fanotify_perm_event_info *event; 173 int fd = response_struct->fd; 174 int response = response_struct->response; 175 176 pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group, 177 fd, response); 178 /* 179 * make sure the response is valid, if invalid we do nothing and either 180 * userspace can send a valid response or we will clean it up after the 181 * timeout 182 */ 183 switch (response & ~FAN_AUDIT) { 184 case FAN_ALLOW: 185 case FAN_DENY: 186 break; 187 default: 188 return -EINVAL; 189 } 190 191 if (fd < 0) 192 return -EINVAL; 193 194 if ((response & FAN_AUDIT) && !group->fanotify_data.audit) 195 return -EINVAL; 196 197 event = dequeue_event(group, fd); 198 if (!event) 199 return -ENOENT; 200 201 event->response = response; 202 wake_up(&group->fanotify_data.access_waitq); 203 204 return 0; 205 } 206 207 static ssize_t copy_event_to_user(struct fsnotify_group *group, 208 struct fsnotify_event *event, 209 char __user *buf) 210 { 211 struct fanotify_event_metadata fanotify_event_metadata; 212 struct file *f; 213 int fd, ret; 214 215 pr_debug("%s: group=%p event=%p\n", __func__, group, event); 216 217 ret = fill_event_metadata(group, &fanotify_event_metadata, event, &f); 218 if (ret < 0) 219 return ret; 220 221 fd = fanotify_event_metadata.fd; 222 ret = -EFAULT; 223 if (copy_to_user(buf, &fanotify_event_metadata, 224 fanotify_event_metadata.event_len)) 225 goto out_close_fd; 226 227 if (fanotify_is_perm_event(event->mask)) 228 FANOTIFY_PE(event)->fd = fd; 229 230 if (fd != FAN_NOFD) 231 fd_install(fd, f); 232 return fanotify_event_metadata.event_len; 233 234 out_close_fd: 235 if (fd != FAN_NOFD) { 236 put_unused_fd(fd); 237 fput(f); 238 } 239 return ret; 240 } 241 242 /* intofiy userspace file descriptor functions */ 243 static __poll_t fanotify_poll(struct file *file, poll_table *wait) 244 { 245 struct fsnotify_group *group = file->private_data; 246 __poll_t ret = 0; 247 248 poll_wait(file, &group->notification_waitq, wait); 249 spin_lock(&group->notification_lock); 250 if (!fsnotify_notify_queue_is_empty(group)) 251 ret = EPOLLIN | EPOLLRDNORM; 252 spin_unlock(&group->notification_lock); 253 254 return ret; 255 } 256 257 static ssize_t fanotify_read(struct file *file, char __user *buf, 258 size_t count, loff_t *pos) 259 { 260 struct fsnotify_group *group; 261 struct fsnotify_event *kevent; 262 char __user *start; 263 int ret; 264 DEFINE_WAIT_FUNC(wait, woken_wake_function); 265 266 start = buf; 267 group = file->private_data; 268 269 pr_debug("%s: group=%p\n", __func__, group); 270 271 add_wait_queue(&group->notification_waitq, &wait); 272 while (1) { 273 spin_lock(&group->notification_lock); 274 kevent = get_one_event(group, count); 275 spin_unlock(&group->notification_lock); 276 277 if (IS_ERR(kevent)) { 278 ret = PTR_ERR(kevent); 279 break; 280 } 281 282 if (!kevent) { 283 ret = -EAGAIN; 284 if (file->f_flags & O_NONBLOCK) 285 break; 286 287 ret = -ERESTARTSYS; 288 if (signal_pending(current)) 289 break; 290 291 if (start != buf) 292 break; 293 294 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 295 continue; 296 } 297 298 ret = copy_event_to_user(group, kevent, buf); 299 if (unlikely(ret == -EOPENSTALE)) { 300 /* 301 * We cannot report events with stale fd so drop it. 302 * Setting ret to 0 will continue the event loop and 303 * do the right thing if there are no more events to 304 * read (i.e. return bytes read, -EAGAIN or wait). 305 */ 306 ret = 0; 307 } 308 309 /* 310 * Permission events get queued to wait for response. Other 311 * events can be destroyed now. 312 */ 313 if (!fanotify_is_perm_event(kevent->mask)) { 314 fsnotify_destroy_event(group, kevent); 315 } else { 316 if (ret <= 0) { 317 FANOTIFY_PE(kevent)->response = FAN_DENY; 318 wake_up(&group->fanotify_data.access_waitq); 319 } else { 320 spin_lock(&group->notification_lock); 321 list_add_tail(&kevent->list, 322 &group->fanotify_data.access_list); 323 spin_unlock(&group->notification_lock); 324 } 325 } 326 if (ret < 0) 327 break; 328 buf += ret; 329 count -= ret; 330 } 331 remove_wait_queue(&group->notification_waitq, &wait); 332 333 if (start != buf && ret != -EFAULT) 334 ret = buf - start; 335 return ret; 336 } 337 338 static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos) 339 { 340 struct fanotify_response response = { .fd = -1, .response = -1 }; 341 struct fsnotify_group *group; 342 int ret; 343 344 if (!IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) 345 return -EINVAL; 346 347 group = file->private_data; 348 349 if (count > sizeof(response)) 350 count = sizeof(response); 351 352 pr_debug("%s: group=%p count=%zu\n", __func__, group, count); 353 354 if (copy_from_user(&response, buf, count)) 355 return -EFAULT; 356 357 ret = process_access_response(group, &response); 358 if (ret < 0) 359 count = ret; 360 361 return count; 362 } 363 364 static int fanotify_release(struct inode *ignored, struct file *file) 365 { 366 struct fsnotify_group *group = file->private_data; 367 struct fanotify_perm_event_info *event, *next; 368 struct fsnotify_event *fsn_event; 369 370 /* 371 * Stop new events from arriving in the notification queue. since 372 * userspace cannot use fanotify fd anymore, no event can enter or 373 * leave access_list by now either. 374 */ 375 fsnotify_group_stop_queueing(group); 376 377 /* 378 * Process all permission events on access_list and notification queue 379 * and simulate reply from userspace. 380 */ 381 spin_lock(&group->notification_lock); 382 list_for_each_entry_safe(event, next, &group->fanotify_data.access_list, 383 fae.fse.list) { 384 pr_debug("%s: found group=%p event=%p\n", __func__, group, 385 event); 386 387 list_del_init(&event->fae.fse.list); 388 event->response = FAN_ALLOW; 389 } 390 391 /* 392 * Destroy all non-permission events. For permission events just 393 * dequeue them and set the response. They will be freed once the 394 * response is consumed and fanotify_get_response() returns. 395 */ 396 while (!fsnotify_notify_queue_is_empty(group)) { 397 fsn_event = fsnotify_remove_first_event(group); 398 if (!(fsn_event->mask & FAN_ALL_PERM_EVENTS)) { 399 spin_unlock(&group->notification_lock); 400 fsnotify_destroy_event(group, fsn_event); 401 spin_lock(&group->notification_lock); 402 } else { 403 FANOTIFY_PE(fsn_event)->response = FAN_ALLOW; 404 } 405 } 406 spin_unlock(&group->notification_lock); 407 408 /* Response for all permission events it set, wakeup waiters */ 409 wake_up(&group->fanotify_data.access_waitq); 410 411 /* matches the fanotify_init->fsnotify_alloc_group */ 412 fsnotify_destroy_group(group); 413 414 return 0; 415 } 416 417 static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 418 { 419 struct fsnotify_group *group; 420 struct fsnotify_event *fsn_event; 421 void __user *p; 422 int ret = -ENOTTY; 423 size_t send_len = 0; 424 425 group = file->private_data; 426 427 p = (void __user *) arg; 428 429 switch (cmd) { 430 case FIONREAD: 431 spin_lock(&group->notification_lock); 432 list_for_each_entry(fsn_event, &group->notification_list, list) 433 send_len += FAN_EVENT_METADATA_LEN; 434 spin_unlock(&group->notification_lock); 435 ret = put_user(send_len, (int __user *) p); 436 break; 437 } 438 439 return ret; 440 } 441 442 static const struct file_operations fanotify_fops = { 443 .show_fdinfo = fanotify_show_fdinfo, 444 .poll = fanotify_poll, 445 .read = fanotify_read, 446 .write = fanotify_write, 447 .fasync = NULL, 448 .release = fanotify_release, 449 .unlocked_ioctl = fanotify_ioctl, 450 .compat_ioctl = fanotify_ioctl, 451 .llseek = noop_llseek, 452 }; 453 454 static int fanotify_find_path(int dfd, const char __user *filename, 455 struct path *path, unsigned int flags) 456 { 457 int ret; 458 459 pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__, 460 dfd, filename, flags); 461 462 if (filename == NULL) { 463 struct fd f = fdget(dfd); 464 465 ret = -EBADF; 466 if (!f.file) 467 goto out; 468 469 ret = -ENOTDIR; 470 if ((flags & FAN_MARK_ONLYDIR) && 471 !(S_ISDIR(file_inode(f.file)->i_mode))) { 472 fdput(f); 473 goto out; 474 } 475 476 *path = f.file->f_path; 477 path_get(path); 478 fdput(f); 479 } else { 480 unsigned int lookup_flags = 0; 481 482 if (!(flags & FAN_MARK_DONT_FOLLOW)) 483 lookup_flags |= LOOKUP_FOLLOW; 484 if (flags & FAN_MARK_ONLYDIR) 485 lookup_flags |= LOOKUP_DIRECTORY; 486 487 ret = user_path_at(dfd, filename, lookup_flags, path); 488 if (ret) 489 goto out; 490 } 491 492 /* you can only watch an inode if you have read permissions on it */ 493 ret = inode_permission(path->dentry->d_inode, MAY_READ); 494 if (ret) 495 path_put(path); 496 out: 497 return ret; 498 } 499 500 static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, 501 __u32 mask, 502 unsigned int flags, 503 int *destroy) 504 { 505 __u32 oldmask = 0; 506 507 spin_lock(&fsn_mark->lock); 508 if (!(flags & FAN_MARK_IGNORED_MASK)) { 509 __u32 tmask = fsn_mark->mask & ~mask; 510 511 if (flags & FAN_MARK_ONDIR) 512 tmask &= ~FAN_ONDIR; 513 514 oldmask = fsn_mark->mask; 515 fsn_mark->mask = tmask; 516 } else { 517 __u32 tmask = fsn_mark->ignored_mask & ~mask; 518 if (flags & FAN_MARK_ONDIR) 519 tmask &= ~FAN_ONDIR; 520 fsn_mark->ignored_mask = tmask; 521 } 522 *destroy = !(fsn_mark->mask | fsn_mark->ignored_mask); 523 spin_unlock(&fsn_mark->lock); 524 525 return mask & oldmask; 526 } 527 528 static int fanotify_remove_mark(struct fsnotify_group *group, 529 fsnotify_connp_t *connp, __u32 mask, 530 unsigned int flags) 531 { 532 struct fsnotify_mark *fsn_mark = NULL; 533 __u32 removed; 534 int destroy_mark; 535 536 mutex_lock(&group->mark_mutex); 537 fsn_mark = fsnotify_find_mark(connp, group); 538 if (!fsn_mark) { 539 mutex_unlock(&group->mark_mutex); 540 return -ENOENT; 541 } 542 543 removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, 544 &destroy_mark); 545 if (removed & fsnotify_conn_mask(fsn_mark->connector)) 546 fsnotify_recalc_mask(fsn_mark->connector); 547 if (destroy_mark) 548 fsnotify_detach_mark(fsn_mark); 549 mutex_unlock(&group->mark_mutex); 550 if (destroy_mark) 551 fsnotify_free_mark(fsn_mark); 552 553 /* matches the fsnotify_find_mark() */ 554 fsnotify_put_mark(fsn_mark); 555 return 0; 556 } 557 558 static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group, 559 struct vfsmount *mnt, __u32 mask, 560 unsigned int flags) 561 { 562 return fanotify_remove_mark(group, &real_mount(mnt)->mnt_fsnotify_marks, 563 mask, flags); 564 } 565 566 static int fanotify_remove_inode_mark(struct fsnotify_group *group, 567 struct inode *inode, __u32 mask, 568 unsigned int flags) 569 { 570 return fanotify_remove_mark(group, &inode->i_fsnotify_marks, mask, 571 flags); 572 } 573 574 static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, 575 __u32 mask, 576 unsigned int flags) 577 { 578 __u32 oldmask = -1; 579 580 spin_lock(&fsn_mark->lock); 581 if (!(flags & FAN_MARK_IGNORED_MASK)) { 582 __u32 tmask = fsn_mark->mask | mask; 583 584 if (flags & FAN_MARK_ONDIR) 585 tmask |= FAN_ONDIR; 586 587 oldmask = fsn_mark->mask; 588 fsn_mark->mask = tmask; 589 } else { 590 __u32 tmask = fsn_mark->ignored_mask | mask; 591 if (flags & FAN_MARK_ONDIR) 592 tmask |= FAN_ONDIR; 593 594 fsn_mark->ignored_mask = tmask; 595 if (flags & FAN_MARK_IGNORED_SURV_MODIFY) 596 fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY; 597 } 598 spin_unlock(&fsn_mark->lock); 599 600 return mask & ~oldmask; 601 } 602 603 static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group, 604 fsnotify_connp_t *connp, 605 unsigned int type) 606 { 607 struct fsnotify_mark *mark; 608 int ret; 609 610 if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) 611 return ERR_PTR(-ENOSPC); 612 613 mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); 614 if (!mark) 615 return ERR_PTR(-ENOMEM); 616 617 fsnotify_init_mark(mark, group); 618 ret = fsnotify_add_mark_locked(mark, connp, type, 0); 619 if (ret) { 620 fsnotify_put_mark(mark); 621 return ERR_PTR(ret); 622 } 623 624 return mark; 625 } 626 627 628 static int fanotify_add_mark(struct fsnotify_group *group, 629 fsnotify_connp_t *connp, unsigned int type, 630 __u32 mask, unsigned int flags) 631 { 632 struct fsnotify_mark *fsn_mark; 633 __u32 added; 634 635 mutex_lock(&group->mark_mutex); 636 fsn_mark = fsnotify_find_mark(connp, group); 637 if (!fsn_mark) { 638 fsn_mark = fanotify_add_new_mark(group, connp, type); 639 if (IS_ERR(fsn_mark)) { 640 mutex_unlock(&group->mark_mutex); 641 return PTR_ERR(fsn_mark); 642 } 643 } 644 added = fanotify_mark_add_to_mask(fsn_mark, mask, flags); 645 if (added & ~fsnotify_conn_mask(fsn_mark->connector)) 646 fsnotify_recalc_mask(fsn_mark->connector); 647 mutex_unlock(&group->mark_mutex); 648 649 fsnotify_put_mark(fsn_mark); 650 return 0; 651 } 652 653 static int fanotify_add_vfsmount_mark(struct fsnotify_group *group, 654 struct vfsmount *mnt, __u32 mask, 655 unsigned int flags) 656 { 657 return fanotify_add_mark(group, &real_mount(mnt)->mnt_fsnotify_marks, 658 FSNOTIFY_OBJ_TYPE_VFSMOUNT, mask, flags); 659 } 660 661 static int fanotify_add_inode_mark(struct fsnotify_group *group, 662 struct inode *inode, __u32 mask, 663 unsigned int flags) 664 { 665 pr_debug("%s: group=%p inode=%p\n", __func__, group, inode); 666 667 /* 668 * If some other task has this inode open for write we should not add 669 * an ignored mark, unless that ignored mark is supposed to survive 670 * modification changes anyway. 671 */ 672 if ((flags & FAN_MARK_IGNORED_MASK) && 673 !(flags & FAN_MARK_IGNORED_SURV_MODIFY) && 674 (atomic_read(&inode->i_writecount) > 0)) 675 return 0; 676 677 return fanotify_add_mark(group, &inode->i_fsnotify_marks, 678 FSNOTIFY_OBJ_TYPE_INODE, mask, flags); 679 } 680 681 /* fanotify syscalls */ 682 SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 683 { 684 struct fsnotify_group *group; 685 int f_flags, fd; 686 struct user_struct *user; 687 struct fanotify_event_info *oevent; 688 689 pr_debug("%s: flags=%d event_f_flags=%d\n", 690 __func__, flags, event_f_flags); 691 692 if (!capable(CAP_SYS_ADMIN)) 693 return -EPERM; 694 695 #ifdef CONFIG_AUDITSYSCALL 696 if (flags & ~(FAN_ALL_INIT_FLAGS | FAN_ENABLE_AUDIT)) 697 #else 698 if (flags & ~FAN_ALL_INIT_FLAGS) 699 #endif 700 return -EINVAL; 701 702 if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS) 703 return -EINVAL; 704 705 switch (event_f_flags & O_ACCMODE) { 706 case O_RDONLY: 707 case O_RDWR: 708 case O_WRONLY: 709 break; 710 default: 711 return -EINVAL; 712 } 713 714 user = get_current_user(); 715 if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) { 716 free_uid(user); 717 return -EMFILE; 718 } 719 720 f_flags = O_RDWR | FMODE_NONOTIFY; 721 if (flags & FAN_CLOEXEC) 722 f_flags |= O_CLOEXEC; 723 if (flags & FAN_NONBLOCK) 724 f_flags |= O_NONBLOCK; 725 726 /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */ 727 group = fsnotify_alloc_group(&fanotify_fsnotify_ops); 728 if (IS_ERR(group)) { 729 free_uid(user); 730 return PTR_ERR(group); 731 } 732 733 group->fanotify_data.user = user; 734 atomic_inc(&user->fanotify_listeners); 735 group->memcg = get_mem_cgroup_from_mm(current->mm); 736 737 oevent = fanotify_alloc_event(group, NULL, FS_Q_OVERFLOW, NULL); 738 if (unlikely(!oevent)) { 739 fd = -ENOMEM; 740 goto out_destroy_group; 741 } 742 group->overflow_event = &oevent->fse; 743 744 if (force_o_largefile()) 745 event_f_flags |= O_LARGEFILE; 746 group->fanotify_data.f_flags = event_f_flags; 747 init_waitqueue_head(&group->fanotify_data.access_waitq); 748 INIT_LIST_HEAD(&group->fanotify_data.access_list); 749 switch (flags & FAN_ALL_CLASS_BITS) { 750 case FAN_CLASS_NOTIF: 751 group->priority = FS_PRIO_0; 752 break; 753 case FAN_CLASS_CONTENT: 754 group->priority = FS_PRIO_1; 755 break; 756 case FAN_CLASS_PRE_CONTENT: 757 group->priority = FS_PRIO_2; 758 break; 759 default: 760 fd = -EINVAL; 761 goto out_destroy_group; 762 } 763 764 if (flags & FAN_UNLIMITED_QUEUE) { 765 fd = -EPERM; 766 if (!capable(CAP_SYS_ADMIN)) 767 goto out_destroy_group; 768 group->max_events = UINT_MAX; 769 } else { 770 group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS; 771 } 772 773 if (flags & FAN_UNLIMITED_MARKS) { 774 fd = -EPERM; 775 if (!capable(CAP_SYS_ADMIN)) 776 goto out_destroy_group; 777 group->fanotify_data.max_marks = UINT_MAX; 778 } else { 779 group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS; 780 } 781 782 if (flags & FAN_ENABLE_AUDIT) { 783 fd = -EPERM; 784 if (!capable(CAP_AUDIT_WRITE)) 785 goto out_destroy_group; 786 group->fanotify_data.audit = true; 787 } 788 789 fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags); 790 if (fd < 0) 791 goto out_destroy_group; 792 793 return fd; 794 795 out_destroy_group: 796 fsnotify_destroy_group(group); 797 return fd; 798 } 799 800 static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, 801 int dfd, const char __user *pathname) 802 { 803 struct inode *inode = NULL; 804 struct vfsmount *mnt = NULL; 805 struct fsnotify_group *group; 806 struct fd f; 807 struct path path; 808 u32 valid_mask = FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD; 809 int ret; 810 811 pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n", 812 __func__, fanotify_fd, flags, dfd, pathname, mask); 813 814 /* we only use the lower 32 bits as of right now. */ 815 if (mask & ((__u64)0xffffffff << 32)) 816 return -EINVAL; 817 818 if (flags & ~FAN_ALL_MARK_FLAGS) 819 return -EINVAL; 820 switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) { 821 case FAN_MARK_ADD: /* fallthrough */ 822 case FAN_MARK_REMOVE: 823 if (!mask) 824 return -EINVAL; 825 break; 826 case FAN_MARK_FLUSH: 827 if (flags & ~(FAN_MARK_MOUNT | FAN_MARK_FLUSH)) 828 return -EINVAL; 829 break; 830 default: 831 return -EINVAL; 832 } 833 834 if (mask & FAN_ONDIR) { 835 flags |= FAN_MARK_ONDIR; 836 mask &= ~FAN_ONDIR; 837 } 838 839 if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) 840 valid_mask |= FAN_ALL_PERM_EVENTS; 841 842 if (mask & ~valid_mask) 843 return -EINVAL; 844 845 f = fdget(fanotify_fd); 846 if (unlikely(!f.file)) 847 return -EBADF; 848 849 /* verify that this is indeed an fanotify instance */ 850 ret = -EINVAL; 851 if (unlikely(f.file->f_op != &fanotify_fops)) 852 goto fput_and_out; 853 group = f.file->private_data; 854 855 /* 856 * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF. These are not 857 * allowed to set permissions events. 858 */ 859 ret = -EINVAL; 860 if (mask & FAN_ALL_PERM_EVENTS && 861 group->priority == FS_PRIO_0) 862 goto fput_and_out; 863 864 if (flags & FAN_MARK_FLUSH) { 865 ret = 0; 866 if (flags & FAN_MARK_MOUNT) 867 fsnotify_clear_vfsmount_marks_by_group(group); 868 else 869 fsnotify_clear_inode_marks_by_group(group); 870 goto fput_and_out; 871 } 872 873 ret = fanotify_find_path(dfd, pathname, &path, flags); 874 if (ret) 875 goto fput_and_out; 876 877 /* inode held in place by reference to path; group by fget on fd */ 878 if (!(flags & FAN_MARK_MOUNT)) 879 inode = path.dentry->d_inode; 880 else 881 mnt = path.mnt; 882 883 /* create/update an inode mark */ 884 switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) { 885 case FAN_MARK_ADD: 886 if (flags & FAN_MARK_MOUNT) 887 ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags); 888 else 889 ret = fanotify_add_inode_mark(group, inode, mask, flags); 890 break; 891 case FAN_MARK_REMOVE: 892 if (flags & FAN_MARK_MOUNT) 893 ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags); 894 else 895 ret = fanotify_remove_inode_mark(group, inode, mask, flags); 896 break; 897 default: 898 ret = -EINVAL; 899 } 900 901 path_put(&path); 902 fput_and_out: 903 fdput(f); 904 return ret; 905 } 906 907 SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags, 908 __u64, mask, int, dfd, 909 const char __user *, pathname) 910 { 911 return do_fanotify_mark(fanotify_fd, flags, mask, dfd, pathname); 912 } 913 914 #ifdef CONFIG_COMPAT 915 COMPAT_SYSCALL_DEFINE6(fanotify_mark, 916 int, fanotify_fd, unsigned int, flags, 917 __u32, mask0, __u32, mask1, int, dfd, 918 const char __user *, pathname) 919 { 920 return do_fanotify_mark(fanotify_fd, flags, 921 #ifdef __BIG_ENDIAN 922 ((__u64)mask0 << 32) | mask1, 923 #else 924 ((__u64)mask1 << 32) | mask0, 925 #endif 926 dfd, pathname); 927 } 928 #endif 929 930 /* 931 * fanotify_user_setup - Our initialization function. Note that we cannot return 932 * error because we have compiled-in VFS hooks. So an (unlikely) failure here 933 * must result in panic(). 934 */ 935 static int __init fanotify_user_setup(void) 936 { 937 fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, 938 SLAB_PANIC|SLAB_ACCOUNT); 939 fanotify_event_cachep = KMEM_CACHE(fanotify_event_info, SLAB_PANIC); 940 if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) { 941 fanotify_perm_event_cachep = 942 KMEM_CACHE(fanotify_perm_event_info, SLAB_PANIC); 943 } 944 945 return 0; 946 } 947 device_initcall(fanotify_user_setup); 948