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