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_lock held. 53 */ 54 static struct fsnotify_event *get_one_event(struct fsnotify_group *group, 55 size_t count) 56 { 57 assert_spin_locked(&group->notification_lock); 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_lock 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->notification_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->notification_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 spin_lock(&group->notification_lock); 248 if (!fsnotify_notify_queue_is_empty(group)) 249 ret = POLLIN | POLLRDNORM; 250 spin_unlock(&group->notification_lock); 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 spin_lock(&group->notification_lock); 272 kevent = get_one_event(group, count); 273 spin_unlock(&group->notification_lock); 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->notification_lock); 313 list_add_tail(&kevent->list, 314 &group->fanotify_data.access_list); 315 spin_unlock(&group->notification_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 struct fsnotify_event *fsn_event; 362 363 /* 364 * Stop new events from arriving in the notification queue. since 365 * userspace cannot use fanotify fd anymore, no event can enter or 366 * leave access_list by now either. 367 */ 368 fsnotify_group_stop_queueing(group); 369 370 /* 371 * Process all permission events on access_list and notification queue 372 * and simulate reply from userspace. 373 */ 374 spin_lock(&group->notification_lock); 375 list_for_each_entry_safe(event, next, &group->fanotify_data.access_list, 376 fae.fse.list) { 377 pr_debug("%s: found group=%p event=%p\n", __func__, group, 378 event); 379 380 list_del_init(&event->fae.fse.list); 381 event->response = FAN_ALLOW; 382 } 383 384 /* 385 * Destroy all non-permission events. For permission events just 386 * dequeue them and set the response. They will be freed once the 387 * response is consumed and fanotify_get_response() returns. 388 */ 389 while (!fsnotify_notify_queue_is_empty(group)) { 390 fsn_event = fsnotify_remove_first_event(group); 391 if (!(fsn_event->mask & FAN_ALL_PERM_EVENTS)) { 392 spin_unlock(&group->notification_lock); 393 fsnotify_destroy_event(group, fsn_event); 394 spin_lock(&group->notification_lock); 395 } else 396 FANOTIFY_PE(fsn_event)->response = FAN_ALLOW; 397 } 398 spin_unlock(&group->notification_lock); 399 400 /* Response for all permission events it set, wakeup waiters */ 401 wake_up(&group->fanotify_data.access_waitq); 402 #endif 403 404 /* matches the fanotify_init->fsnotify_alloc_group */ 405 fsnotify_destroy_group(group); 406 407 return 0; 408 } 409 410 static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 411 { 412 struct fsnotify_group *group; 413 struct fsnotify_event *fsn_event; 414 void __user *p; 415 int ret = -ENOTTY; 416 size_t send_len = 0; 417 418 group = file->private_data; 419 420 p = (void __user *) arg; 421 422 switch (cmd) { 423 case FIONREAD: 424 spin_lock(&group->notification_lock); 425 list_for_each_entry(fsn_event, &group->notification_list, list) 426 send_len += FAN_EVENT_METADATA_LEN; 427 spin_unlock(&group->notification_lock); 428 ret = put_user(send_len, (int __user *) p); 429 break; 430 } 431 432 return ret; 433 } 434 435 static const struct file_operations fanotify_fops = { 436 .show_fdinfo = fanotify_show_fdinfo, 437 .poll = fanotify_poll, 438 .read = fanotify_read, 439 .write = fanotify_write, 440 .fasync = NULL, 441 .release = fanotify_release, 442 .unlocked_ioctl = fanotify_ioctl, 443 .compat_ioctl = fanotify_ioctl, 444 .llseek = noop_llseek, 445 }; 446 447 static void fanotify_free_mark(struct fsnotify_mark *fsn_mark) 448 { 449 kmem_cache_free(fanotify_mark_cache, fsn_mark); 450 } 451 452 static int fanotify_find_path(int dfd, const char __user *filename, 453 struct path *path, unsigned int flags) 454 { 455 int ret; 456 457 pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__, 458 dfd, filename, flags); 459 460 if (filename == NULL) { 461 struct fd f = fdget(dfd); 462 463 ret = -EBADF; 464 if (!f.file) 465 goto out; 466 467 ret = -ENOTDIR; 468 if ((flags & FAN_MARK_ONLYDIR) && 469 !(S_ISDIR(file_inode(f.file)->i_mode))) { 470 fdput(f); 471 goto out; 472 } 473 474 *path = f.file->f_path; 475 path_get(path); 476 fdput(f); 477 } else { 478 unsigned int lookup_flags = 0; 479 480 if (!(flags & FAN_MARK_DONT_FOLLOW)) 481 lookup_flags |= LOOKUP_FOLLOW; 482 if (flags & FAN_MARK_ONLYDIR) 483 lookup_flags |= LOOKUP_DIRECTORY; 484 485 ret = user_path_at(dfd, filename, lookup_flags, path); 486 if (ret) 487 goto out; 488 } 489 490 /* you can only watch an inode if you have read permissions on it */ 491 ret = inode_permission(path->dentry->d_inode, MAY_READ); 492 if (ret) 493 path_put(path); 494 out: 495 return ret; 496 } 497 498 static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, 499 __u32 mask, 500 unsigned int flags, 501 int *destroy) 502 { 503 __u32 oldmask = 0; 504 505 spin_lock(&fsn_mark->lock); 506 if (!(flags & FAN_MARK_IGNORED_MASK)) { 507 __u32 tmask = fsn_mark->mask & ~mask; 508 509 if (flags & FAN_MARK_ONDIR) 510 tmask &= ~FAN_ONDIR; 511 512 oldmask = fsn_mark->mask; 513 fsnotify_set_mark_mask_locked(fsn_mark, tmask); 514 } else { 515 __u32 tmask = fsn_mark->ignored_mask & ~mask; 516 if (flags & FAN_MARK_ONDIR) 517 tmask &= ~FAN_ONDIR; 518 519 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask); 520 } 521 *destroy = !(fsn_mark->mask | fsn_mark->ignored_mask); 522 spin_unlock(&fsn_mark->lock); 523 524 return mask & oldmask; 525 } 526 527 static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group, 528 struct vfsmount *mnt, __u32 mask, 529 unsigned int flags) 530 { 531 struct fsnotify_mark *fsn_mark = NULL; 532 __u32 removed; 533 int destroy_mark; 534 535 mutex_lock(&group->mark_mutex); 536 fsn_mark = fsnotify_find_vfsmount_mark(group, mnt); 537 if (!fsn_mark) { 538 mutex_unlock(&group->mark_mutex); 539 return -ENOENT; 540 } 541 542 removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, 543 &destroy_mark); 544 if (destroy_mark) 545 fsnotify_detach_mark(fsn_mark); 546 mutex_unlock(&group->mark_mutex); 547 if (destroy_mark) 548 fsnotify_free_mark(fsn_mark); 549 550 fsnotify_put_mark(fsn_mark); 551 if (removed & real_mount(mnt)->mnt_fsnotify_mask) 552 fsnotify_recalc_vfsmount_mask(mnt); 553 554 return 0; 555 } 556 557 static int fanotify_remove_inode_mark(struct fsnotify_group *group, 558 struct inode *inode, __u32 mask, 559 unsigned int flags) 560 { 561 struct fsnotify_mark *fsn_mark = NULL; 562 __u32 removed; 563 int destroy_mark; 564 565 mutex_lock(&group->mark_mutex); 566 fsn_mark = fsnotify_find_inode_mark(group, inode); 567 if (!fsn_mark) { 568 mutex_unlock(&group->mark_mutex); 569 return -ENOENT; 570 } 571 572 removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, 573 &destroy_mark); 574 if (destroy_mark) 575 fsnotify_detach_mark(fsn_mark); 576 mutex_unlock(&group->mark_mutex); 577 if (destroy_mark) 578 fsnotify_free_mark(fsn_mark); 579 580 /* matches the fsnotify_find_inode_mark() */ 581 fsnotify_put_mark(fsn_mark); 582 if (removed & inode->i_fsnotify_mask) 583 fsnotify_recalc_inode_mask(inode); 584 585 return 0; 586 } 587 588 static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, 589 __u32 mask, 590 unsigned int flags) 591 { 592 __u32 oldmask = -1; 593 594 spin_lock(&fsn_mark->lock); 595 if (!(flags & FAN_MARK_IGNORED_MASK)) { 596 __u32 tmask = fsn_mark->mask | mask; 597 598 if (flags & FAN_MARK_ONDIR) 599 tmask |= FAN_ONDIR; 600 601 oldmask = fsn_mark->mask; 602 fsnotify_set_mark_mask_locked(fsn_mark, tmask); 603 } else { 604 __u32 tmask = fsn_mark->ignored_mask | mask; 605 if (flags & FAN_MARK_ONDIR) 606 tmask |= FAN_ONDIR; 607 608 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask); 609 if (flags & FAN_MARK_IGNORED_SURV_MODIFY) 610 fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY; 611 } 612 spin_unlock(&fsn_mark->lock); 613 614 return mask & ~oldmask; 615 } 616 617 static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group, 618 struct inode *inode, 619 struct vfsmount *mnt) 620 { 621 struct fsnotify_mark *mark; 622 int ret; 623 624 if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) 625 return ERR_PTR(-ENOSPC); 626 627 mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); 628 if (!mark) 629 return ERR_PTR(-ENOMEM); 630 631 fsnotify_init_mark(mark, fanotify_free_mark); 632 ret = fsnotify_add_mark_locked(mark, group, inode, mnt, 0); 633 if (ret) { 634 fsnotify_put_mark(mark); 635 return ERR_PTR(ret); 636 } 637 638 return mark; 639 } 640 641 642 static int fanotify_add_vfsmount_mark(struct fsnotify_group *group, 643 struct vfsmount *mnt, __u32 mask, 644 unsigned int flags) 645 { 646 struct fsnotify_mark *fsn_mark; 647 __u32 added; 648 649 mutex_lock(&group->mark_mutex); 650 fsn_mark = fsnotify_find_vfsmount_mark(group, mnt); 651 if (!fsn_mark) { 652 fsn_mark = fanotify_add_new_mark(group, NULL, mnt); 653 if (IS_ERR(fsn_mark)) { 654 mutex_unlock(&group->mark_mutex); 655 return PTR_ERR(fsn_mark); 656 } 657 } 658 added = fanotify_mark_add_to_mask(fsn_mark, mask, flags); 659 mutex_unlock(&group->mark_mutex); 660 661 if (added & ~real_mount(mnt)->mnt_fsnotify_mask) 662 fsnotify_recalc_vfsmount_mask(mnt); 663 664 fsnotify_put_mark(fsn_mark); 665 return 0; 666 } 667 668 static int fanotify_add_inode_mark(struct fsnotify_group *group, 669 struct inode *inode, __u32 mask, 670 unsigned int flags) 671 { 672 struct fsnotify_mark *fsn_mark; 673 __u32 added; 674 675 pr_debug("%s: group=%p inode=%p\n", __func__, group, inode); 676 677 /* 678 * If some other task has this inode open for write we should not add 679 * an ignored mark, unless that ignored mark is supposed to survive 680 * modification changes anyway. 681 */ 682 if ((flags & FAN_MARK_IGNORED_MASK) && 683 !(flags & FAN_MARK_IGNORED_SURV_MODIFY) && 684 (atomic_read(&inode->i_writecount) > 0)) 685 return 0; 686 687 mutex_lock(&group->mark_mutex); 688 fsn_mark = fsnotify_find_inode_mark(group, inode); 689 if (!fsn_mark) { 690 fsn_mark = fanotify_add_new_mark(group, inode, NULL); 691 if (IS_ERR(fsn_mark)) { 692 mutex_unlock(&group->mark_mutex); 693 return PTR_ERR(fsn_mark); 694 } 695 } 696 added = fanotify_mark_add_to_mask(fsn_mark, mask, flags); 697 mutex_unlock(&group->mark_mutex); 698 699 if (added & ~inode->i_fsnotify_mask) 700 fsnotify_recalc_inode_mask(inode); 701 702 fsnotify_put_mark(fsn_mark); 703 return 0; 704 } 705 706 /* fanotify syscalls */ 707 SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 708 { 709 struct fsnotify_group *group; 710 int f_flags, fd; 711 struct user_struct *user; 712 struct fanotify_event_info *oevent; 713 714 pr_debug("%s: flags=%d event_f_flags=%d\n", 715 __func__, flags, event_f_flags); 716 717 if (!capable(CAP_SYS_ADMIN)) 718 return -EPERM; 719 720 if (flags & ~FAN_ALL_INIT_FLAGS) 721 return -EINVAL; 722 723 if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS) 724 return -EINVAL; 725 726 switch (event_f_flags & O_ACCMODE) { 727 case O_RDONLY: 728 case O_RDWR: 729 case O_WRONLY: 730 break; 731 default: 732 return -EINVAL; 733 } 734 735 user = get_current_user(); 736 if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) { 737 free_uid(user); 738 return -EMFILE; 739 } 740 741 f_flags = O_RDWR | FMODE_NONOTIFY; 742 if (flags & FAN_CLOEXEC) 743 f_flags |= O_CLOEXEC; 744 if (flags & FAN_NONBLOCK) 745 f_flags |= O_NONBLOCK; 746 747 /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */ 748 group = fsnotify_alloc_group(&fanotify_fsnotify_ops); 749 if (IS_ERR(group)) { 750 free_uid(user); 751 return PTR_ERR(group); 752 } 753 754 group->fanotify_data.user = user; 755 atomic_inc(&user->fanotify_listeners); 756 757 oevent = fanotify_alloc_event(NULL, FS_Q_OVERFLOW, NULL); 758 if (unlikely(!oevent)) { 759 fd = -ENOMEM; 760 goto out_destroy_group; 761 } 762 group->overflow_event = &oevent->fse; 763 764 if (force_o_largefile()) 765 event_f_flags |= O_LARGEFILE; 766 group->fanotify_data.f_flags = event_f_flags; 767 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 768 init_waitqueue_head(&group->fanotify_data.access_waitq); 769 INIT_LIST_HEAD(&group->fanotify_data.access_list); 770 #endif 771 switch (flags & FAN_ALL_CLASS_BITS) { 772 case FAN_CLASS_NOTIF: 773 group->priority = FS_PRIO_0; 774 break; 775 case FAN_CLASS_CONTENT: 776 group->priority = FS_PRIO_1; 777 break; 778 case FAN_CLASS_PRE_CONTENT: 779 group->priority = FS_PRIO_2; 780 break; 781 default: 782 fd = -EINVAL; 783 goto out_destroy_group; 784 } 785 786 if (flags & FAN_UNLIMITED_QUEUE) { 787 fd = -EPERM; 788 if (!capable(CAP_SYS_ADMIN)) 789 goto out_destroy_group; 790 group->max_events = UINT_MAX; 791 } else { 792 group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS; 793 } 794 795 if (flags & FAN_UNLIMITED_MARKS) { 796 fd = -EPERM; 797 if (!capable(CAP_SYS_ADMIN)) 798 goto out_destroy_group; 799 group->fanotify_data.max_marks = UINT_MAX; 800 } else { 801 group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS; 802 } 803 804 fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags); 805 if (fd < 0) 806 goto out_destroy_group; 807 808 return fd; 809 810 out_destroy_group: 811 fsnotify_destroy_group(group); 812 return fd; 813 } 814 815 SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags, 816 __u64, mask, int, dfd, 817 const char __user *, pathname) 818 { 819 struct inode *inode = NULL; 820 struct vfsmount *mnt = NULL; 821 struct fsnotify_group *group; 822 struct fd f; 823 struct path path; 824 int ret; 825 826 pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n", 827 __func__, fanotify_fd, flags, dfd, pathname, mask); 828 829 /* we only use the lower 32 bits as of right now. */ 830 if (mask & ((__u64)0xffffffff << 32)) 831 return -EINVAL; 832 833 if (flags & ~FAN_ALL_MARK_FLAGS) 834 return -EINVAL; 835 switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) { 836 case FAN_MARK_ADD: /* fallthrough */ 837 case FAN_MARK_REMOVE: 838 if (!mask) 839 return -EINVAL; 840 break; 841 case FAN_MARK_FLUSH: 842 if (flags & ~(FAN_MARK_MOUNT | FAN_MARK_FLUSH)) 843 return -EINVAL; 844 break; 845 default: 846 return -EINVAL; 847 } 848 849 if (mask & FAN_ONDIR) { 850 flags |= FAN_MARK_ONDIR; 851 mask &= ~FAN_ONDIR; 852 } 853 854 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 855 if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD)) 856 #else 857 if (mask & ~(FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD)) 858 #endif 859 return -EINVAL; 860 861 f = fdget(fanotify_fd); 862 if (unlikely(!f.file)) 863 return -EBADF; 864 865 /* verify that this is indeed an fanotify instance */ 866 ret = -EINVAL; 867 if (unlikely(f.file->f_op != &fanotify_fops)) 868 goto fput_and_out; 869 group = f.file->private_data; 870 871 /* 872 * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF. These are not 873 * allowed to set permissions events. 874 */ 875 ret = -EINVAL; 876 if (mask & FAN_ALL_PERM_EVENTS && 877 group->priority == FS_PRIO_0) 878 goto fput_and_out; 879 880 if (flags & FAN_MARK_FLUSH) { 881 ret = 0; 882 if (flags & FAN_MARK_MOUNT) 883 fsnotify_clear_vfsmount_marks_by_group(group); 884 else 885 fsnotify_clear_inode_marks_by_group(group); 886 goto fput_and_out; 887 } 888 889 ret = fanotify_find_path(dfd, pathname, &path, flags); 890 if (ret) 891 goto fput_and_out; 892 893 /* inode held in place by reference to path; group by fget on fd */ 894 if (!(flags & FAN_MARK_MOUNT)) 895 inode = path.dentry->d_inode; 896 else 897 mnt = path.mnt; 898 899 /* create/update an inode mark */ 900 switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) { 901 case FAN_MARK_ADD: 902 if (flags & FAN_MARK_MOUNT) 903 ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags); 904 else 905 ret = fanotify_add_inode_mark(group, inode, mask, flags); 906 break; 907 case FAN_MARK_REMOVE: 908 if (flags & FAN_MARK_MOUNT) 909 ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags); 910 else 911 ret = fanotify_remove_inode_mark(group, inode, mask, flags); 912 break; 913 default: 914 ret = -EINVAL; 915 } 916 917 path_put(&path); 918 fput_and_out: 919 fdput(f); 920 return ret; 921 } 922 923 #ifdef CONFIG_COMPAT 924 COMPAT_SYSCALL_DEFINE6(fanotify_mark, 925 int, fanotify_fd, unsigned int, flags, 926 __u32, mask0, __u32, mask1, int, dfd, 927 const char __user *, pathname) 928 { 929 return sys_fanotify_mark(fanotify_fd, flags, 930 #ifdef __BIG_ENDIAN 931 ((__u64)mask0 << 32) | mask1, 932 #else 933 ((__u64)mask1 << 32) | mask0, 934 #endif 935 dfd, pathname); 936 } 937 #endif 938 939 /* 940 * fanotify_user_setup - Our initialization function. Note that we cannot return 941 * error because we have compiled-in VFS hooks. So an (unlikely) failure here 942 * must result in panic(). 943 */ 944 static int __init fanotify_user_setup(void) 945 { 946 fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC); 947 fanotify_event_cachep = KMEM_CACHE(fanotify_event_info, SLAB_PANIC); 948 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 949 fanotify_perm_event_cachep = KMEM_CACHE(fanotify_perm_event_info, 950 SLAB_PANIC); 951 #endif 952 953 return 0; 954 } 955 device_initcall(fanotify_user_setup); 956