fs/notify/fanotify/fanotify_user.c

   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
  17 #include <asm/ioctls.h>
  18
  19 extern const struct fsnotify_ops fanotify_fsnotify_ops;
  20
  21 static struct kmem_cache *fanotify_mark_cache __read_mostly;
  22 static struct kmem_cache *fanotify_response_event_cache __read_mostly;
  23
  24 struct fanotify_response_event {
  25         struct list_head list;
  26         __s32 fd;
  27         struct fsnotify_event *event;
  28 };
  29
  30 /*
  31  * Get an fsnotify notification event if one exists and is small
  32  * enough to fit in "count". Return an error pointer if the count
  33  * is not large enough.
  34  *
  35  * Called with the group->notification_mutex held.
  36  */
  37 static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
  38                                             size_t count)
  39 {
  40         BUG_ON(!mutex_is_locked(&group->notification_mutex));
  41
  42         pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
  43
  44         if (fsnotify_notify_queue_is_empty(group))
  45                 return NULL;
  46
  47         if (FAN_EVENT_METADATA_LEN > count)
  48                 return ERR_PTR(-EINVAL);
  49
  50         /* held the notification_mutex the whole time, so this is the
  51          * same event we peeked above */
  52         return fsnotify_remove_notify_event(group);
  53 }
  54
  55 static int create_fd(struct fsnotify_group *group, struct fsnotify_event *event)
  56 {
  57         int client_fd;
  58         struct dentry *dentry;
  59         struct vfsmount *mnt;
  60         struct file *new_file;
  61
  62         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
  63
  64         client_fd = get_unused_fd();
  65         if (client_fd < 0)
  66                 return client_fd;
  67
  68         if (event->data_type != FSNOTIFY_EVENT_PATH) {
  69                 WARN_ON(1);
  70                 put_unused_fd(client_fd);
  71                 return -EINVAL;
  72         }
  73
  74         /*
  75          * we need a new file handle for the userspace program so it can read even if it was
  76          * originally opened O_WRONLY.
  77          */
  78         dentry = dget(event->path.dentry);
  79         mnt = mntget(event->path.mnt);
  80         /* it's possible this event was an overflow event.  in that case dentry and mnt
  81          * are NULL;  That's fine, just don't call dentry open */
  82         if (dentry && mnt)
  83                 new_file = dentry_open(dentry, mnt,
  84                                        group->fanotify_data.f_flags | FMODE_NONOTIFY,
  85                                        current_cred());
  86         else
  87                 new_file = ERR_PTR(-EOVERFLOW);
  88         if (IS_ERR(new_file)) {
  89                 /*
  90                  * we still send an event even if we can't open the file.  this
  91                  * can happen when say tasks are gone and we try to open their
  92                  * /proc files or we try to open a WRONLY file like in sysfs
  93                  * we just send the errno to userspace since there isn't much
  94                  * else we can do.
  95                  */
  96                 put_unused_fd(client_fd);
  97                 client_fd = PTR_ERR(new_file);
  98         } else {
  99                 fd_install(client_fd, new_file);
 100         }
 101
 102         return client_fd;
 103 }
 104
 105 static ssize_t fill_event_metadata(struct fsnotify_group *group,
 106                                    struct fanotify_event_metadata *metadata,
 107                                    struct fsnotify_event *event)
 108 {
 109         pr_debug("%s: group=%p metadata=%p event=%p\n", __func__,
 110                  group, metadata, event);
 111
 112         metadata->event_len = FAN_EVENT_METADATA_LEN;
 113         metadata->vers = FANOTIFY_METADATA_VERSION;
 114         metadata->mask = event->mask & FAN_ALL_OUTGOING_EVENTS;
 115         metadata->pid = pid_vnr(event->tgid);
 116         metadata->fd = create_fd(group, event);
 117
 118         return metadata->fd;
 119 }
 120
 121 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 122 static struct fanotify_response_event *dequeue_re(struct fsnotify_group *group,
 123                                                   __s32 fd)
 124 {
 125         struct fanotify_response_event *re, *return_re = NULL;
 126
 127         mutex_lock(&group->fanotify_data.access_mutex);
 128         list_for_each_entry(re, &group->fanotify_data.access_list, list) {
 129                 if (re->fd != fd)
 130                         continue;
 131
 132                 list_del_init(&re->list);
 133                 return_re = re;
 134                 break;
 135         }
 136         mutex_unlock(&group->fanotify_data.access_mutex);
 137
 138         pr_debug("%s: found return_re=%p\n", __func__, return_re);
 139
 140         return return_re;
 141 }
 142
 143 static int process_access_response(struct fsnotify_group *group,
 144                                    struct fanotify_response *response_struct)
 145 {
 146         struct fanotify_response_event *re;
 147         __s32 fd = response_struct->fd;
 148         __u32 response = response_struct->response;
 149
 150         pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group,
 151                  fd, response);
 152         /*
 153          * make sure the response is valid, if invalid we do nothing and either
 154          * userspace can send a valid responce or we will clean it up after the
 155          * timeout
 156          */
 157         switch (response) {
 158         case FAN_ALLOW:
 159         case FAN_DENY:
 160                 break;
 161         default:
 162                 return -EINVAL;
 163         }
 164
 165         if (fd < 0)
 166                 return -EINVAL;
 167
 168         re = dequeue_re(group, fd);
 169         if (!re)
 170                 return -ENOENT;
 171
 172         re->event->response = response;
 173
 174         wake_up(&group->fanotify_data.access_waitq);
 175
 176         kmem_cache_free(fanotify_response_event_cache, re);
 177
 178         return 0;
 179 }
 180
 181 static int prepare_for_access_response(struct fsnotify_group *group,
 182                                        struct fsnotify_event *event,
 183                                        __s32 fd)
 184 {
 185         struct fanotify_response_event *re;
 186
 187         if (!(event->mask & FAN_ALL_PERM_EVENTS))
 188                 return 0;
 189
 190         re = kmem_cache_alloc(fanotify_response_event_cache, GFP_KERNEL);
 191         if (!re)
 192                 return -ENOMEM;
 193
 194         re->event = event;
 195         re->fd = fd;
 196
 197         mutex_lock(&group->fanotify_data.access_mutex);
 198         list_add_tail(&re->list, &group->fanotify_data.access_list);
 199         mutex_unlock(&group->fanotify_data.access_mutex);
 200
 201         return 0;
 202 }
 203
 204 static void remove_access_response(struct fsnotify_group *group,
 205                                    struct fsnotify_event *event,
 206                                    __s32 fd)
 207 {
 208         struct fanotify_response_event *re;
 209
 210         if (!(event->mask & FAN_ALL_PERM_EVENTS))
 211                 return;
 212
 213         re = dequeue_re(group, fd);
 214         if (!re)
 215                 return;
 216
 217         BUG_ON(re->event != event);
 218
 219         kmem_cache_free(fanotify_response_event_cache, re);
 220
 221         return;
 222 }
 223 #else
 224 static int prepare_for_access_response(struct fsnotify_group *group,
 225                                        struct fsnotify_event *event,
 226                                        __s32 fd)
 227 {
 228         return 0;
 229 }
 230
 231 static void remove_access_response(struct fsnotify_group *group,
 232                                    struct fsnotify_event *event,
 233                                    __s32 fd)
 234 {
 235         return;
 236 }
 237 #endif
 238
 239 static ssize_t copy_event_to_user(struct fsnotify_group *group,
 240                                   struct fsnotify_event *event,
 241                                   char __user *buf)
 242 {
 243         struct fanotify_event_metadata fanotify_event_metadata;
 244         int fd, ret;
 245
 246         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
 247
 248         fd = fill_event_metadata(group, &fanotify_event_metadata, event);
 249         if (fd < 0)
 250                 return fd;
 251
 252         ret = prepare_for_access_response(group, event, fd);
 253         if (ret)
 254                 goto out_close_fd;
 255
 256         ret = -EFAULT;
 257         if (copy_to_user(buf, &fanotify_event_metadata, FAN_EVENT_METADATA_LEN))
 258                 goto out_kill_access_response;
 259
 260         return FAN_EVENT_METADATA_LEN;
 261
 262 out_kill_access_response:
 263         remove_access_response(group, event, fd);
 264 out_close_fd:
 265         sys_close(fd);
 266         return ret;
 267 }
 268
 269 /* intofiy userspace file descriptor functions */
 270 static unsigned int fanotify_poll(struct file *file, poll_table *wait)
 271 {
 272         struct fsnotify_group *group = file->private_data;
 273         int ret = 0;
 274
 275         poll_wait(file, &group->notification_waitq, wait);
 276         mutex_lock(&group->notification_mutex);
 277         if (!fsnotify_notify_queue_is_empty(group))
 278                 ret = POLLIN | POLLRDNORM;
 279         mutex_unlock(&group->notification_mutex);
 280
 281         return ret;
 282 }
 283
 284 static ssize_t fanotify_read(struct file *file, char __user *buf,
 285                              size_t count, loff_t *pos)
 286 {
 287         struct fsnotify_group *group;
 288         struct fsnotify_event *kevent;
 289         char __user *start;
 290         int ret;
 291         DEFINE_WAIT(wait);
 292
 293         start = buf;
 294         group = file->private_data;
 295
 296         pr_debug("%s: group=%p\n", __func__, group);
 297
 298         while (1) {
 299                 prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE);
 300
 301                 mutex_lock(&group->notification_mutex);
 302                 kevent = get_one_event(group, count);
 303                 mutex_unlock(&group->notification_mutex);
 304
 305                 if (kevent) {
 306                         ret = PTR_ERR(kevent);
 307                         if (IS_ERR(kevent))
 308                                 break;
 309                         ret = copy_event_to_user(group, kevent, buf);
 310                         fsnotify_put_event(kevent);
 311                         if (ret < 0)
 312                                 break;
 313                         buf += ret;
 314                         count -= ret;
 315                         continue;
 316                 }
 317
 318                 ret = -EAGAIN;
 319                 if (file->f_flags & O_NONBLOCK)
 320                         break;
 321                 ret = -EINTR;
 322                 if (signal_pending(current))
 323                         break;
 324
 325                 if (start != buf)
 326                         break;
 327
 328                 schedule();
 329         }
 330
 331         finish_wait(&group->notification_waitq, &wait);
 332         if (start != buf && ret != -EFAULT)
 333                 ret = buf - start;
 334         return ret;
 335 }
 336
 337 static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
 338 {
 339 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 340         struct fanotify_response response = { .fd = -1, .response = -1 };
 341         struct fsnotify_group *group;
 342         int ret;
 343
 344         group = file->private_data;
 345
 346         if (count > sizeof(response))
 347                 count = sizeof(response);
 348
 349         pr_debug("%s: group=%p count=%zu\n", __func__, group, count);
 350
 351         if (copy_from_user(&response, buf, count))
 352                 return -EFAULT;
 353
 354         ret = process_access_response(group, &response);
 355         if (ret < 0)
 356                 count = ret;
 357
 358         return count;
 359 #else
 360         return -EINVAL;
 361 #endif
 362 }
 363
 364 static int fanotify_release(struct inode *ignored, struct file *file)
 365 {
 366         struct fsnotify_group *group = file->private_data;
 367
 368         pr_debug("%s: file=%p group=%p\n", __func__, file, group);
 369
 370         /* matches the fanotify_init->fsnotify_alloc_group */
 371         fsnotify_put_group(group);
 372
 373         return 0;
 374 }
 375
 376 static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 377 {
 378         struct fsnotify_group *group;
 379         struct fsnotify_event_holder *holder;
 380         void __user *p;
 381         int ret = -ENOTTY;
 382         size_t send_len = 0;
 383
 384         group = file->private_data;
 385
 386         p = (void __user *) arg;
 387
 388         switch (cmd) {
 389         case FIONREAD:
 390                 mutex_lock(&group->notification_mutex);
 391                 list_for_each_entry(holder, &group->notification_list, event_list)
 392                         send_len += FAN_EVENT_METADATA_LEN;
 393                 mutex_unlock(&group->notification_mutex);
 394                 ret = put_user(send_len, (int __user *) p);
 395                 break;
 396         }
 397
 398         return ret;
 399 }
 400
 401 static const struct file_operations fanotify_fops = {
 402         .poll           = fanotify_poll,
 403         .read           = fanotify_read,
 404         .write          = fanotify_write,
 405         .fasync         = NULL,
 406         .release        = fanotify_release,
 407         .unlocked_ioctl = fanotify_ioctl,
 408         .compat_ioctl   = fanotify_ioctl,
 409 };
 410
 411 static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
 412 {
 413         kmem_cache_free(fanotify_mark_cache, fsn_mark);
 414 }
 415
 416 static int fanotify_find_path(int dfd, const char __user *filename,
 417                               struct path *path, unsigned int flags)
 418 {
 419         int ret;
 420
 421         pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__,
 422                  dfd, filename, flags);
 423
 424         if (filename == NULL) {
 425                 struct file *file;
 426                 int fput_needed;
 427
 428                 ret = -EBADF;
 429                 file = fget_light(dfd, &fput_needed);
 430                 if (!file)
 431                         goto out;
 432
 433                 ret = -ENOTDIR;
 434                 if ((flags & FAN_MARK_ONLYDIR) &&
 435                     !(S_ISDIR(file->f_path.dentry->d_inode->i_mode))) {
 436                         fput_light(file, fput_needed);
 437                         goto out;
 438                 }
 439
 440                 *path = file->f_path;
 441                 path_get(path);
 442                 fput_light(file, fput_needed);
 443         } else {
 444                 unsigned int lookup_flags = 0;
 445
 446                 if (!(flags & FAN_MARK_DONT_FOLLOW))
 447                         lookup_flags |= LOOKUP_FOLLOW;
 448                 if (flags & FAN_MARK_ONLYDIR)
 449                         lookup_flags |= LOOKUP_DIRECTORY;
 450
 451                 ret = user_path_at(dfd, filename, lookup_flags, path);
 452                 if (ret)
 453                         goto out;
 454         }
 455
 456         /* you can only watch an inode if you have read permissions on it */
 457         ret = inode_permission(path->dentry->d_inode, MAY_READ);
 458         if (ret)
 459                 path_put(path);
 460 out:
 461         return ret;
 462 }
 463
 464 static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
 465                                             __u32 mask,
 466                                             unsigned int flags)
 467 {
 468         __u32 oldmask;
 469
 470         spin_lock(&fsn_mark->lock);
 471         if (!(flags & FAN_MARK_IGNORED_MASK)) {
 472                 oldmask = fsn_mark->mask;
 473                 fsnotify_set_mark_mask_locked(fsn_mark, (oldmask & ~mask));
 474         } else {
 475                 oldmask = fsn_mark->ignored_mask;
 476                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, (oldmask & ~mask));
 477         }
 478         spin_unlock(&fsn_mark->lock);
 479
 480         if (!(oldmask & ~mask))
 481                 fsnotify_destroy_mark(fsn_mark);
 482
 483         return mask & oldmask;
 484 }
 485
 486 static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
 487                                          struct vfsmount *mnt, __u32 mask,
 488                                          unsigned int flags)
 489 {
 490         struct fsnotify_mark *fsn_mark = NULL;
 491         __u32 removed;
 492
 493         fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
 494         if (!fsn_mark)
 495                 return -ENOENT;
 496
 497         removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags);
 498         fsnotify_put_mark(fsn_mark);
 499         if (removed & mnt->mnt_fsnotify_mask)
 500                 fsnotify_recalc_vfsmount_mask(mnt);
 501
 502         return 0;
 503 }
 504
 505 static int fanotify_remove_inode_mark(struct fsnotify_group *group,
 506                                       struct inode *inode, __u32 mask,
 507                                       unsigned int flags)
 508 {
 509         struct fsnotify_mark *fsn_mark = NULL;
 510         __u32 removed;
 511
 512         fsn_mark = fsnotify_find_inode_mark(group, inode);
 513         if (!fsn_mark)
 514                 return -ENOENT;
 515
 516         removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags);
 517         /* matches the fsnotify_find_inode_mark() */
 518         fsnotify_put_mark(fsn_mark);
 519         if (removed & inode->i_fsnotify_mask)
 520                 fsnotify_recalc_inode_mask(inode);
 521
 522         return 0;
 523 }
 524
 525 static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
 526                                        __u32 mask,
 527                                        unsigned int flags)
 528 {
 529         __u32 oldmask;
 530
 531         spin_lock(&fsn_mark->lock);
 532         if (!(flags & FAN_MARK_IGNORED_MASK)) {
 533                 oldmask = fsn_mark->mask;
 534                 fsnotify_set_mark_mask_locked(fsn_mark, (oldmask | mask));
 535         } else {
 536                 oldmask = fsn_mark->ignored_mask;
 537                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, (oldmask | mask));
 538                 if (flags & FAN_MARK_IGNORED_SURV_MODIFY)
 539                         fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
 540         }
 541         spin_unlock(&fsn_mark->lock);
 542
 543         return mask & ~oldmask;
 544 }
 545
 546 static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
 547                                       struct vfsmount *mnt, __u32 mask,
 548                                       unsigned int flags)
 549 {
 550         struct fsnotify_mark *fsn_mark;
 551         __u32 added;
 552
 553         fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
 554         if (!fsn_mark) {
 555                 int ret;
 556
 557                 fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
 558                 if (!fsn_mark)
 559                         return -ENOMEM;
 560
 561                 fsnotify_init_mark(fsn_mark, fanotify_free_mark);
 562                 ret = fsnotify_add_mark(fsn_mark, group, NULL, mnt, 0);
 563                 if (ret) {
 564                         fanotify_free_mark(fsn_mark);
 565                         return ret;
 566                 }
 567         }
 568         added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
 569         fsnotify_put_mark(fsn_mark);
 570         if (added & ~mnt->mnt_fsnotify_mask)
 571                 fsnotify_recalc_vfsmount_mask(mnt);
 572
 573         return 0;
 574 }
 575
 576 static int fanotify_add_inode_mark(struct fsnotify_group *group,
 577                                    struct inode *inode, __u32 mask,
 578                                    unsigned int flags)
 579 {
 580         struct fsnotify_mark *fsn_mark;
 581         __u32 added;
 582
 583         pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
 584
 585         fsn_mark = fsnotify_find_inode_mark(group, inode);
 586         if (!fsn_mark) {
 587                 int ret;
 588
 589                 fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
 590                 if (!fsn_mark)
 591                         return -ENOMEM;
 592
 593                 fsnotify_init_mark(fsn_mark, fanotify_free_mark);
 594                 ret = fsnotify_add_mark(fsn_mark, group, inode, NULL, 0);
 595                 if (ret) {
 596                         fanotify_free_mark(fsn_mark);
 597                         return ret;
 598                 }
 599         }
 600         added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
 601         fsnotify_put_mark(fsn_mark);
 602         if (added & ~inode->i_fsnotify_mask)
 603                 fsnotify_recalc_inode_mask(inode);
 604         return 0;
 605 }
 606
 607 /* fanotify syscalls */
 608 SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 609 {
 610         struct fsnotify_group *group;
 611         int f_flags, fd;
 612
 613         pr_debug("%s: flags=%d event_f_flags=%d\n",
 614                 __func__, flags, event_f_flags);
 615
 616         if (!capable(CAP_SYS_ADMIN))
 617                 return -EACCES;
 618
 619         if (flags & ~FAN_ALL_INIT_FLAGS)
 620                 return -EINVAL;
 621
 622         f_flags = O_RDWR | FMODE_NONOTIFY;
 623         if (flags & FAN_CLOEXEC)
 624                 f_flags |= O_CLOEXEC;
 625         if (flags & FAN_NONBLOCK)
 626                 f_flags |= O_NONBLOCK;
 627
 628         /* fsnotify_alloc_group takes a ref.  Dropped in fanotify_release */
 629         group = fsnotify_alloc_group(&fanotify_fsnotify_ops);
 630         if (IS_ERR(group))
 631                 return PTR_ERR(group);
 632
 633         group->fanotify_data.f_flags = event_f_flags;
 634 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 635         mutex_init(&group->fanotify_data.access_mutex);
 636         init_waitqueue_head(&group->fanotify_data.access_waitq);
 637         INIT_LIST_HEAD(&group->fanotify_data.access_list);
 638 #endif
 639
 640         fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
 641         if (fd < 0)
 642                 goto out_put_group;
 643
 644         return fd;
 645
 646 out_put_group:
 647         fsnotify_put_group(group);
 648         return fd;
 649 }
 650
 651 SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
 652                               __u64 mask, int dfd,
 653                               const char  __user * pathname)
 654 {
 655         struct inode *inode = NULL;
 656         struct vfsmount *mnt = NULL;
 657         struct fsnotify_group *group;
 658         struct file *filp;
 659         struct path path;
 660         int ret, fput_needed;
 661
 662         pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
 663                  __func__, fanotify_fd, flags, dfd, pathname, mask);
 664
 665         /* we only use the lower 32 bits as of right now. */
 666         if (mask & ((__u64)0xffffffff << 32))
 667                 return -EINVAL;
 668
 669         if (flags & ~FAN_ALL_MARK_FLAGS)
 670                 return -EINVAL;
 671         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
 672         case FAN_MARK_ADD:
 673         case FAN_MARK_REMOVE:
 674         case FAN_MARK_FLUSH:
 675                 break;
 676         default:
 677                 return -EINVAL;
 678         }
 679 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 680         if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD))
 681 #else
 682         if (mask & ~(FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD))
 683 #endif
 684                 return -EINVAL;
 685
 686         filp = fget_light(fanotify_fd, &fput_needed);
 687         if (unlikely(!filp))
 688                 return -EBADF;
 689
 690         /* verify that this is indeed an fanotify instance */
 691         ret = -EINVAL;
 692         if (unlikely(filp->f_op != &fanotify_fops))
 693                 goto fput_and_out;
 694
 695         ret = fanotify_find_path(dfd, pathname, &path, flags);
 696         if (ret)
 697                 goto fput_and_out;
 698
 699         /* inode held in place by reference to path; group by fget on fd */
 700         if (!(flags & FAN_MARK_MOUNT))
 701                 inode = path.dentry->d_inode;
 702         else
 703                 mnt = path.mnt;
 704         group = filp->private_data;
 705
 706         /* create/update an inode mark */
 707         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
 708         case FAN_MARK_ADD:
 709                 if (flags & FAN_MARK_MOUNT)
 710                         ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags);
 711                 else
 712                         ret = fanotify_add_inode_mark(group, inode, mask, flags);
 713                 break;
 714         case FAN_MARK_REMOVE:
 715                 if (flags & FAN_MARK_MOUNT)
 716                         ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags);
 717                 else
 718                         ret = fanotify_remove_inode_mark(group, inode, mask, flags);
 719                 break;
 720         case FAN_MARK_FLUSH:
 721                 if (flags & FAN_MARK_MOUNT)
 722                         fsnotify_clear_vfsmount_marks_by_group(group);
 723                 else
 724                         fsnotify_clear_inode_marks_by_group(group);
 725                 break;
 726         default:
 727                 ret = -EINVAL;
 728         }
 729
 730         path_put(&path);
 731 fput_and_out:
 732         fput_light(filp, fput_needed);
 733         return ret;
 734 }
 735
 736 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 737 asmlinkage long SyS_fanotify_mark(long fanotify_fd, long flags, __u64 mask,
 738                                   long dfd, long pathname)
 739 {
 740         return SYSC_fanotify_mark((int) fanotify_fd, (unsigned int) flags,
 741                                   mask, (int) dfd,
 742                                   (const char  __user *) pathname);
 743 }
 744 SYSCALL_ALIAS(sys_fanotify_mark, SyS_fanotify_mark);
 745 #endif
 746
 747 /*
 748  * fanotify_user_setup - Our initialization function.  Note that we cannnot return
 749  * error because we have compiled-in VFS hooks.  So an (unlikely) failure here
 750  * must result in panic().
 751  */
 752 static int __init fanotify_user_setup(void)
 753 {
 754         fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC);
 755         fanotify_response_event_cache = KMEM_CACHE(fanotify_response_event,
 756                                                    SLAB_PANIC);
 757
 758         return 0;
 759 }
 760 device_initcall(fanotify_user_setup);