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