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 41extern const struct fsnotify_ops fanotify_fsnotify_ops; 42 43static struct kmem_cache *fanotify_mark_cache __read_mostly; 44struct kmem_cache *fanotify_event_cachep __read_mostly; 45struct 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 */ 54static 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 72static 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 114static 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 145static 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 167static 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 203static 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 232out_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 */ 241static 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 255static 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 328static 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 355static 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 397static 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 422static 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 434static void fanotify_free_mark(struct fsnotify_mark *fsn_mark) 435{ 436 kmem_cache_free(fanotify_mark_cache, fsn_mark); 437} 438 439static 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); 481out: 482 return ret; 483} 484 485static __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 = 0; 491 492 spin_lock(&fsn_mark->lock); 493 if (!(flags & FAN_MARK_IGNORED_MASK)) { 494 __u32 tmask = fsn_mark->mask & ~mask; 495 496 if (flags & FAN_MARK_ONDIR) 497 tmask &= ~FAN_ONDIR; 498 499 oldmask = fsn_mark->mask; 500 fsnotify_set_mark_mask_locked(fsn_mark, tmask); 501 } else { 502 __u32 tmask = fsn_mark->ignored_mask & ~mask; 503 if (flags & FAN_MARK_ONDIR) 504 tmask &= ~FAN_ONDIR; 505 506 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask); 507 } 508 *destroy = !(fsn_mark->mask | fsn_mark->ignored_mask); 509 spin_unlock(&fsn_mark->lock); 510 511 return mask & oldmask; 512} 513 514static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group, 515 struct vfsmount *mnt, __u32 mask, 516 unsigned int flags) 517{ 518 struct fsnotify_mark *fsn_mark = NULL; 519 __u32 removed; 520 int destroy_mark; 521 522 mutex_lock(&group->mark_mutex); 523 fsn_mark = fsnotify_find_vfsmount_mark(group, mnt); 524 if (!fsn_mark) { 525 mutex_unlock(&group->mark_mutex); 526 return -ENOENT; 527 } 528 529 removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, 530 &destroy_mark); 531 if (destroy_mark) 532 fsnotify_detach_mark(fsn_mark); 533 mutex_unlock(&group->mark_mutex); 534 if (destroy_mark) 535 fsnotify_free_mark(fsn_mark); 536 537 fsnotify_put_mark(fsn_mark); 538 if (removed & real_mount(mnt)->mnt_fsnotify_mask) 539 fsnotify_recalc_vfsmount_mask(mnt); 540 541 return 0; 542} 543 544static int fanotify_remove_inode_mark(struct fsnotify_group *group, 545 struct inode *inode, __u32 mask, 546 unsigned int flags) 547{ 548 struct fsnotify_mark *fsn_mark = NULL; 549 __u32 removed; 550 int destroy_mark; 551 552 mutex_lock(&group->mark_mutex); 553 fsn_mark = fsnotify_find_inode_mark(group, inode); 554 if (!fsn_mark) { 555 mutex_unlock(&group->mark_mutex); 556 return -ENOENT; 557 } 558 559 removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, 560 &destroy_mark); 561 if (destroy_mark) 562 fsnotify_detach_mark(fsn_mark); 563 mutex_unlock(&group->mark_mutex); 564 if (destroy_mark) 565 fsnotify_free_mark(fsn_mark); 566 567 /* matches the fsnotify_find_inode_mark() */ 568 fsnotify_put_mark(fsn_mark); 569 if (removed & inode->i_fsnotify_mask) 570 fsnotify_recalc_inode_mask(inode); 571 572 return 0; 573} 574 575static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, 576 __u32 mask, 577 unsigned int flags) 578{ 579 __u32 oldmask = -1; 580 581 spin_lock(&fsn_mark->lock); 582 if (!(flags & FAN_MARK_IGNORED_MASK)) { 583 __u32 tmask = fsn_mark->mask | mask; 584 585 if (flags & FAN_MARK_ONDIR) 586 tmask |= FAN_ONDIR; 587 588 oldmask = fsn_mark->mask; 589 fsnotify_set_mark_mask_locked(fsn_mark, tmask); 590 } else { 591 __u32 tmask = fsn_mark->ignored_mask | mask; 592 if (flags & FAN_MARK_ONDIR) 593 tmask |= FAN_ONDIR; 594 595 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask); 596 if (flags & FAN_MARK_IGNORED_SURV_MODIFY) 597 fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY; 598 } 599 spin_unlock(&fsn_mark->lock); 600 601 return mask & ~oldmask; 602} 603 604static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group, 605 struct inode *inode, 606 struct vfsmount *mnt) 607{ 608 struct fsnotify_mark *mark; 609 int ret; 610 611 if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) 612 return ERR_PTR(-ENOSPC); 613 614 mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); 615 if (!mark) 616 return ERR_PTR(-ENOMEM); 617 618 fsnotify_init_mark(mark, fanotify_free_mark); 619 ret = fsnotify_add_mark_locked(mark, group, inode, mnt, 0); 620 if (ret) { 621 fsnotify_put_mark(mark); 622 return ERR_PTR(ret); 623 } 624 625 return mark; 626} 627 628 629static int fanotify_add_vfsmount_mark(struct fsnotify_group *group, 630 struct vfsmount *mnt, __u32 mask, 631 unsigned int flags) 632{ 633 struct fsnotify_mark *fsn_mark; 634 __u32 added; 635 636 mutex_lock(&group->mark_mutex); 637 fsn_mark = fsnotify_find_vfsmount_mark(group, mnt); 638 if (!fsn_mark) { 639 fsn_mark = fanotify_add_new_mark(group, NULL, mnt); 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 & ~real_mount(mnt)->mnt_fsnotify_mask) 649 fsnotify_recalc_vfsmount_mask(mnt); 650 651 fsnotify_put_mark(fsn_mark); 652 return 0; 653} 654 655static int fanotify_add_inode_mark(struct fsnotify_group *group, 656 struct inode *inode, __u32 mask, 657 unsigned int flags) 658{ 659 struct fsnotify_mark *fsn_mark; 660 __u32 added; 661 662 pr_debug("%s: group=%p inode=%p\n", __func__, group, inode); 663 664 /* 665 * If some other task has this inode open for write we should not add 666 * an ignored mark, unless that ignored mark is supposed to survive 667 * modification changes anyway. 668 */ 669 if ((flags & FAN_MARK_IGNORED_MASK) && 670 !(flags & FAN_MARK_IGNORED_SURV_MODIFY) && 671 (atomic_read(&inode->i_writecount) > 0)) 672 return 0; 673 674 mutex_lock(&group->mark_mutex); 675 fsn_mark = fsnotify_find_inode_mark(group, inode); 676 if (!fsn_mark) { 677 fsn_mark = fanotify_add_new_mark(group, inode, NULL); 678 if (IS_ERR(fsn_mark)) { 679 mutex_unlock(&group->mark_mutex); 680 return PTR_ERR(fsn_mark); 681 } 682 } 683 added = fanotify_mark_add_to_mask(fsn_mark, mask, flags); 684 mutex_unlock(&group->mark_mutex); 685 686 if (added & ~inode->i_fsnotify_mask) 687 fsnotify_recalc_inode_mask(inode); 688 689 fsnotify_put_mark(fsn_mark); 690 return 0; 691} 692 693/* fanotify syscalls */ 694SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 695{ 696 struct fsnotify_group *group; 697 int f_flags, fd; 698 struct user_struct *user; 699 struct fanotify_event_info *oevent; 700 701 pr_debug("%s: flags=%d event_f_flags=%d\n", 702 __func__, flags, event_f_flags); 703 704 if (!capable(CAP_SYS_ADMIN)) 705 return -EPERM; 706 707 if (flags & ~FAN_ALL_INIT_FLAGS) 708 return -EINVAL; 709 710 if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS) 711 return -EINVAL; 712 713 switch (event_f_flags & O_ACCMODE) { 714 case O_RDONLY: 715 case O_RDWR: 716 case O_WRONLY: 717 break; 718 default: 719 return -EINVAL; 720 } 721 722 user = get_current_user(); 723 if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) { 724 free_uid(user); 725 return -EMFILE; 726 } 727 728 f_flags = O_RDWR | FMODE_NONOTIFY; 729 if (flags & FAN_CLOEXEC) 730 f_flags |= O_CLOEXEC; 731 if (flags & FAN_NONBLOCK) 732 f_flags |= O_NONBLOCK; 733 734 /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */ 735 group = fsnotify_alloc_group(&fanotify_fsnotify_ops); 736 if (IS_ERR(group)) { 737 free_uid(user); 738 return PTR_ERR(group); 739 } 740 741 group->fanotify_data.user = user; 742 atomic_inc(&user->fanotify_listeners); 743 744 oevent = fanotify_alloc_event(NULL, FS_Q_OVERFLOW, NULL); 745 if (unlikely(!oevent)) { 746 fd = -ENOMEM; 747 goto out_destroy_group; 748 } 749 group->overflow_event = &oevent->fse; 750 751 if (force_o_largefile()) 752 event_f_flags |= O_LARGEFILE; 753 group->fanotify_data.f_flags = event_f_flags; 754#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 755 spin_lock_init(&group->fanotify_data.access_lock); 756 init_waitqueue_head(&group->fanotify_data.access_waitq); 757 INIT_LIST_HEAD(&group->fanotify_data.access_list); 758 atomic_set(&group->fanotify_data.bypass_perm, 0); 759#endif 760 switch (flags & FAN_ALL_CLASS_BITS) { 761 case FAN_CLASS_NOTIF: 762 group->priority = FS_PRIO_0; 763 break; 764 case FAN_CLASS_CONTENT: 765 group->priority = FS_PRIO_1; 766 break; 767 case FAN_CLASS_PRE_CONTENT: 768 group->priority = FS_PRIO_2; 769 break; 770 default: 771 fd = -EINVAL; 772 goto out_destroy_group; 773 } 774 775 if (flags & FAN_UNLIMITED_QUEUE) { 776 fd = -EPERM; 777 if (!capable(CAP_SYS_ADMIN)) 778 goto out_destroy_group; 779 group->max_events = UINT_MAX; 780 } else { 781 group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS; 782 } 783 784 if (flags & FAN_UNLIMITED_MARKS) { 785 fd = -EPERM; 786 if (!capable(CAP_SYS_ADMIN)) 787 goto out_destroy_group; 788 group->fanotify_data.max_marks = UINT_MAX; 789 } else { 790 group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS; 791 } 792 793 fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags); 794 if (fd < 0) 795 goto out_destroy_group; 796 797 return fd; 798 799out_destroy_group: 800 fsnotify_destroy_group(group); 801 return fd; 802} 803 804SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags, 805 __u64, mask, int, dfd, 806 const char __user *, pathname) 807{ 808 struct inode *inode = NULL; 809 struct vfsmount *mnt = NULL; 810 struct fsnotify_group *group; 811 struct fd f; 812 struct path path; 813 int ret; 814 815 pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n", 816 __func__, fanotify_fd, flags, dfd, pathname, mask); 817 818 /* we only use the lower 32 bits as of right now. */ 819 if (mask & ((__u64)0xffffffff << 32)) 820 return -EINVAL; 821 822 if (flags & ~FAN_ALL_MARK_FLAGS) 823 return -EINVAL; 824 switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) { 825 case FAN_MARK_ADD: /* fallthrough */ 826 case FAN_MARK_REMOVE: 827 if (!mask) 828 return -EINVAL; 829 break; 830 case FAN_MARK_FLUSH: 831 if (flags & ~(FAN_MARK_MOUNT | FAN_MARK_FLUSH)) 832 return -EINVAL; 833 break; 834 default: 835 return -EINVAL; 836 } 837 838 if (mask & FAN_ONDIR) { 839 flags |= FAN_MARK_ONDIR; 840 mask &= ~FAN_ONDIR; 841 } 842 843#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 844 if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD)) 845#else 846 if (mask & ~(FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD)) 847#endif 848 return -EINVAL; 849 850 f = fdget(fanotify_fd); 851 if (unlikely(!f.file)) 852 return -EBADF; 853 854 /* verify that this is indeed an fanotify instance */ 855 ret = -EINVAL; 856 if (unlikely(f.file->f_op != &fanotify_fops)) 857 goto fput_and_out; 858 group = f.file->private_data; 859 860 /* 861 * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF. These are not 862 * allowed to set permissions events. 863 */ 864 ret = -EINVAL; 865 if (mask & FAN_ALL_PERM_EVENTS && 866 group->priority == FS_PRIO_0) 867 goto fput_and_out; 868 869 if (flags & FAN_MARK_FLUSH) { 870 ret = 0; 871 if (flags & FAN_MARK_MOUNT) 872 fsnotify_clear_vfsmount_marks_by_group(group); 873 else 874 fsnotify_clear_inode_marks_by_group(group); 875 goto fput_and_out; 876 } 877 878 ret = fanotify_find_path(dfd, pathname, &path, flags); 879 if (ret) 880 goto fput_and_out; 881 882 /* inode held in place by reference to path; group by fget on fd */ 883 if (!(flags & FAN_MARK_MOUNT)) 884 inode = path.dentry->d_inode; 885 else 886 mnt = path.mnt; 887 888 /* create/update an inode mark */ 889 switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) { 890 case FAN_MARK_ADD: 891 if (flags & FAN_MARK_MOUNT) 892 ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags); 893 else 894 ret = fanotify_add_inode_mark(group, inode, mask, flags); 895 break; 896 case FAN_MARK_REMOVE: 897 if (flags & FAN_MARK_MOUNT) 898 ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags); 899 else 900 ret = fanotify_remove_inode_mark(group, inode, mask, flags); 901 break; 902 default: 903 ret = -EINVAL; 904 } 905 906 path_put(&path); 907fput_and_out: 908 fdput(f); 909 return ret; 910} 911 912#ifdef CONFIG_COMPAT 913COMPAT_SYSCALL_DEFINE6(fanotify_mark, 914 int, fanotify_fd, unsigned int, flags, 915 __u32, mask0, __u32, mask1, int, dfd, 916 const char __user *, pathname) 917{ 918 return sys_fanotify_mark(fanotify_fd, flags, 919#ifdef __BIG_ENDIAN 920 ((__u64)mask0 << 32) | mask1, 921#else 922 ((__u64)mask1 << 32) | mask0, 923#endif 924 dfd, pathname); 925} 926#endif 927 928/* 929 * fanotify_user_setup - Our initialization function. Note that we cannot return 930 * error because we have compiled-in VFS hooks. So an (unlikely) failure here 931 * must result in panic(). 932 */ 933static int __init fanotify_user_setup(void) 934{ 935 fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC); 936 fanotify_event_cachep = KMEM_CACHE(fanotify_event_info, SLAB_PANIC); 937#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 938 fanotify_perm_event_cachep = KMEM_CACHE(fanotify_perm_event_info, 939 SLAB_PANIC); 940#endif 941 942 return 0; 943} 944device_initcall(fanotify_user_setup); 945