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 #include "../../mount.h"
  20
  21 #define FANOTIFY_DEFAULT_MAX_EVENTS     16384
  22 #define FANOTIFY_DEFAULT_MAX_MARKS      8192
  23 #define FANOTIFY_DEFAULT_MAX_LISTENERS  128
  24
  25 extern const struct fsnotify_ops fanotify_fsnotify_ops;
  26
  27 static struct kmem_cache *fanotify_mark_cache __read_mostly;
  28 static struct kmem_cache *fanotify_response_event_cache __read_mostly;
  29
  30 struct fanotify_response_event {
  31         struct list_head list;
  32         __s32 fd;
  33         struct fsnotify_event *event;
  34 };
  35
  36 /*
  37  * Get an fsnotify notification event if one exists and is small
  38  * enough to fit in "count". Return an error pointer if the count
  39  * is not large enough.
  40  *
  41  * Called with the group->notification_mutex held.
  42  */
  43 static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
  44                                             size_t count)
  45 {
  46         BUG_ON(!mutex_is_locked(&group->notification_mutex));
  47
  48         pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
  49
  50         if (fsnotify_notify_queue_is_empty(group))
  51                 return NULL;
  52
  53         if (FAN_EVENT_METADATA_LEN > count)
  54                 return ERR_PTR(-EINVAL);
  55
  56         /* held the notification_mutex the whole time, so this is the
  57          * same event we peeked above */
  58         return fsnotify_remove_notify_event(group);
  59 }
  60
  61 static int create_fd(struct fsnotify_group *group,
  62                         struct fsnotify_event *event,
  63                         struct file **file)
  64 {
  65         int client_fd;
  66         struct file *new_file;
  67
  68         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
  69
  70         client_fd = get_unused_fd();
  71         if (client_fd < 0)
  72                 return client_fd;
  73
  74         if (event->data_type != FSNOTIFY_EVENT_PATH) {
  75                 WARN_ON(1);
  76                 put_unused_fd(client_fd);
  77                 return -EINVAL;
  78         }
  79
  80         /*
  81          * we need a new file handle for the userspace program so it can read even if it was
  82          * originally opened O_WRONLY.
  83          */
  84         /* it's possible this event was an overflow event.  in that case dentry and mnt
  85          * are NULL;  That's fine, just don't call dentry open */
  86         if (event->path.dentry && event->path.mnt)
  87                 new_file = dentry_open(&event->path,
  88                                        group->fanotify_data.f_flags | FMODE_NONOTIFY,
  89                                        current_cred());
  90         else
  91                 new_file = ERR_PTR(-EOVERFLOW);
  92         if (IS_ERR(new_file)) {
  93                 /*
  94                  * we still send an event even if we can't open the file.  this
  95                  * can happen when say tasks are gone and we try to open their
  96                  * /proc files or we try to open a WRONLY file like in sysfs
  97                  * we just send the errno to userspace since there isn't much
  98                  * else we can do.
  99                  */
 100                 put_unused_fd(client_fd);
 101                 client_fd = PTR_ERR(new_file);
 102         } else {
 103                 *file = new_file;
 104         }
 105
 106         return client_fd;
 107 }
 108
 109 static int fill_event_metadata(struct fsnotify_group *group,
 110                                    struct fanotify_event_metadata *metadata,
 111                                    struct fsnotify_event *event,
 112                                    struct file **file)
 113 {
 114         int ret = 0;
 115
 116         pr_debug("%s: group=%p metadata=%p event=%p\n", __func__,
 117                  group, metadata, event);
 118
 119         *file = NULL;
 120         metadata->event_len = FAN_EVENT_METADATA_LEN;
 121         metadata->metadata_len = FAN_EVENT_METADATA_LEN;
 122         metadata->vers = FANOTIFY_METADATA_VERSION;
 123         metadata->mask = event->mask & FAN_ALL_OUTGOING_EVENTS;
 124         metadata->pid = pid_vnr(event->tgid);
 125         if (unlikely(event->mask & FAN_Q_OVERFLOW))
 126                 metadata->fd = FAN_NOFD;
 127         else {
 128                 metadata->fd = create_fd(group, event, file);
 129                 if (metadata->fd < 0)
 130                         ret = metadata->fd;
 131         }
 132
 133         return ret;
 134 }
 135
 136 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 137 static struct fanotify_response_event *dequeue_re(struct fsnotify_group *group,
 138                                                   __s32 fd)
 139 {
 140         struct fanotify_response_event *re, *return_re = NULL;
 141
 142         mutex_lock(&group->fanotify_data.access_mutex);
 143         list_for_each_entry(re, &group->fanotify_data.access_list, list) {
 144                 if (re->fd != fd)
 145                         continue;
 146
 147                 list_del_init(&re->list);
 148                 return_re = re;
 149                 break;
 150         }
 151         mutex_unlock(&group->fanotify_data.access_mutex);
 152
 153         pr_debug("%s: found return_re=%p\n", __func__, return_re);
 154
 155         return return_re;
 156 }
 157
 158 static int process_access_response(struct fsnotify_group *group,
 159                                    struct fanotify_response *response_struct)
 160 {
 161         struct fanotify_response_event *re;
 162         __s32 fd = response_struct->fd;
 163         __u32 response = response_struct->response;
 164
 165         pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group,
 166                  fd, response);
 167         /*
 168          * make sure the response is valid, if invalid we do nothing and either
 169          * userspace can send a valid response or we will clean it up after the
 170          * timeout
 171          */
 172         switch (response) {
 173         case FAN_ALLOW:
 174         case FAN_DENY:
 175                 break;
 176         default:
 177                 return -EINVAL;
 178         }
 179
 180         if (fd < 0)
 181                 return -EINVAL;
 182
 183         re = dequeue_re(group, fd);
 184         if (!re)
 185                 return -ENOENT;
 186
 187         re->event->response = response;
 188
 189         wake_up(&group->fanotify_data.access_waitq);
 190
 191         kmem_cache_free(fanotify_response_event_cache, re);
 192
 193         return 0;
 194 }
 195
 196 static int prepare_for_access_response(struct fsnotify_group *group,
 197                                        struct fsnotify_event *event,
 198                                        __s32 fd)
 199 {
 200         struct fanotify_response_event *re;
 201
 202         if (!(event->mask & FAN_ALL_PERM_EVENTS))
 203                 return 0;
 204
 205         re = kmem_cache_alloc(fanotify_response_event_cache, GFP_KERNEL);
 206         if (!re)
 207                 return -ENOMEM;
 208
 209         re->event = event;
 210         re->fd = fd;
 211
 212         mutex_lock(&group->fanotify_data.access_mutex);
 213
 214         if (atomic_read(&group->fanotify_data.bypass_perm)) {
 215                 mutex_unlock(&group->fanotify_data.access_mutex);
 216                 kmem_cache_free(fanotify_response_event_cache, re);
 217                 event->response = FAN_ALLOW;
 218                 return 0;
 219         }
 220
 221         list_add_tail(&re->list, &group->fanotify_data.access_list);
 222         mutex_unlock(&group->fanotify_data.access_mutex);
 223
 224         return 0;
 225 }
 226
 227 #else
 228 static int prepare_for_access_response(struct fsnotify_group *group,
 229                                        struct fsnotify_event *event,
 230                                        __s32 fd)
 231 {
 232         return 0;
 233 }
 234
 235 #endif
 236
 237 static ssize_t copy_event_to_user(struct fsnotify_group *group,
 238                                   struct fsnotify_event *event,
 239                                   char __user *buf)
 240 {
 241         struct fanotify_event_metadata fanotify_event_metadata;
 242         struct file *f;
 243         int fd, ret;
 244
 245         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
 246
 247         ret = fill_event_metadata(group, &fanotify_event_metadata, event, &f);
 248         if (ret < 0)
 249                 goto out;
 250
 251         fd = fanotify_event_metadata.fd;
 252         ret = -EFAULT;
 253         if (copy_to_user(buf, &fanotify_event_metadata,
 254                          fanotify_event_metadata.event_len))
 255                 goto out_close_fd;
 256
 257         ret = prepare_for_access_response(group, event, fd);
 258         if (ret)
 259                 goto out_close_fd;
 260
 261         if (fd != FAN_NOFD)
 262                 fd_install(fd, f);
 263         return fanotify_event_metadata.event_len;
 264
 265 out_close_fd:
 266         if (fd != FAN_NOFD) {
 267                 put_unused_fd(fd);
 268                 fput(f);
 269         }
 270 out:
 271 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 272         if (event->mask & FAN_ALL_PERM_EVENTS) {
 273                 event->response = FAN_DENY;
 274                 wake_up(&group->fanotify_data.access_waitq);
 275         }
 276 #endif
 277         return ret;
 278 }
 279
 280 /* intofiy userspace file descriptor functions */
 281 static unsigned int fanotify_poll(struct file *file, poll_table *wait)
 282 {
 283         struct fsnotify_group *group = file->private_data;
 284         int ret = 0;
 285
 286         poll_wait(file, &group->notification_waitq, wait);
 287         mutex_lock(&group->notification_mutex);
 288         if (!fsnotify_notify_queue_is_empty(group))
 289                 ret = POLLIN | POLLRDNORM;
 290         mutex_unlock(&group->notification_mutex);
 291
 292         return ret;
 293 }
 294
 295 static ssize_t fanotify_read(struct file *file, char __user *buf,
 296                              size_t count, loff_t *pos)
 297 {
 298         struct fsnotify_group *group;
 299         struct fsnotify_event *kevent;
 300         char __user *start;
 301         int ret;
 302         DEFINE_WAIT(wait);
 303
 304         start = buf;
 305         group = file->private_data;
 306
 307         pr_debug("%s: group=%p\n", __func__, group);
 308
 309         while (1) {
 310                 prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE);
 311
 312                 mutex_lock(&group->notification_mutex);
 313                 kevent = get_one_event(group, count);
 314                 mutex_unlock(&group->notification_mutex);
 315
 316                 if (kevent) {
 317                         ret = PTR_ERR(kevent);
 318                         if (IS_ERR(kevent))
 319                                 break;
 320                         ret = copy_event_to_user(group, kevent, buf);
 321                         fsnotify_put_event(kevent);
 322                         if (ret < 0)
 323                                 break;
 324                         buf += ret;
 325                         count -= ret;
 326                         continue;
 327                 }
 328
 329                 ret = -EAGAIN;
 330                 if (file->f_flags & O_NONBLOCK)
 331                         break;
 332                 ret = -ERESTARTSYS;
 333                 if (signal_pending(current))
 334                         break;
 335
 336                 if (start != buf)
 337                         break;
 338
 339                 schedule();
 340         }
 341
 342         finish_wait(&group->notification_waitq, &wait);
 343         if (start != buf && ret != -EFAULT)
 344                 ret = buf - start;
 345         return ret;
 346 }
 347
 348 static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
 349 {
 350 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 351         struct fanotify_response response = { .fd = -1, .response = -1 };
 352         struct fsnotify_group *group;
 353         int ret;
 354
 355         group = file->private_data;
 356
 357         if (count > sizeof(response))
 358                 count = sizeof(response);
 359
 360         pr_debug("%s: group=%p count=%zu\n", __func__, group, count);
 361
 362         if (copy_from_user(&response, buf, count))
 363                 return -EFAULT;
 364
 365         ret = process_access_response(group, &response);
 366         if (ret < 0)
 367                 count = ret;
 368
 369         return count;
 370 #else
 371         return -EINVAL;
 372 #endif
 373 }
 374
 375 static int fanotify_release(struct inode *ignored, struct file *file)
 376 {
 377         struct fsnotify_group *group = file->private_data;
 378
 379 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 380         struct fanotify_response_event *re, *lre;
 381
 382         mutex_lock(&group->fanotify_data.access_mutex);
 383
 384         atomic_inc(&group->fanotify_data.bypass_perm);
 385
 386         list_for_each_entry_safe(re, lre, &group->fanotify_data.access_list, list) {
 387                 pr_debug("%s: found group=%p re=%p event=%p\n", __func__, group,
 388                          re, re->event);
 389
 390                 list_del_init(&re->list);
 391                 re->event->response = FAN_ALLOW;
 392
 393                 kmem_cache_free(fanotify_response_event_cache, re);
 394         }
 395         mutex_unlock(&group->fanotify_data.access_mutex);
 396
 397         wake_up(&group->fanotify_data.access_waitq);
 398 #endif
 399         /* matches the fanotify_init->fsnotify_alloc_group */
 400         fsnotify_put_group(group);
 401
 402         return 0;
 403 }
 404
 405 static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 406 {
 407         struct fsnotify_group *group;
 408         struct fsnotify_event_holder *holder;
 409         void __user *p;
 410         int ret = -ENOTTY;
 411         size_t send_len = 0;
 412
 413         group = file->private_data;
 414
 415         p = (void __user *) arg;
 416
 417         switch (cmd) {
 418         case FIONREAD:
 419                 mutex_lock(&group->notification_mutex);
 420                 list_for_each_entry(holder, &group->notification_list, event_list)
 421                         send_len += FAN_EVENT_METADATA_LEN;
 422                 mutex_unlock(&group->notification_mutex);
 423                 ret = put_user(send_len, (int __user *) p);
 424                 break;
 425         }
 426
 427         return ret;
 428 }
 429
 430 static const struct file_operations fanotify_fops = {
 431         .poll           = fanotify_poll,
 432         .read           = fanotify_read,
 433         .write          = fanotify_write,
 434         .fasync         = NULL,
 435         .release        = fanotify_release,
 436         .unlocked_ioctl = fanotify_ioctl,
 437         .compat_ioctl   = fanotify_ioctl,
 438         .llseek         = noop_llseek,
 439 };
 440
 441 static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
 442 {
 443         kmem_cache_free(fanotify_mark_cache, fsn_mark);
 444 }
 445
 446 static int fanotify_find_path(int dfd, const char __user *filename,
 447                               struct path *path, unsigned int flags)
 448 {
 449         int ret;
 450
 451         pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__,
 452                  dfd, filename, flags);
 453
 454         if (filename == NULL) {
 455                 struct fd f = fdget(dfd);
 456
 457                 ret = -EBADF;
 458                 if (!f.file)
 459                         goto out;
 460
 461                 ret = -ENOTDIR;
 462                 if ((flags & FAN_MARK_ONLYDIR) &&
 463                     !(S_ISDIR(f.file->f_path.dentry->d_inode->i_mode))) {
 464                         fdput(f);
 465                         goto out;
 466                 }
 467
 468                 *path = f.file->f_path;
 469                 path_get(path);
 470                 fdput(f);
 471         } else {
 472                 unsigned int lookup_flags = 0;
 473
 474                 if (!(flags & FAN_MARK_DONT_FOLLOW))
 475                         lookup_flags |= LOOKUP_FOLLOW;
 476                 if (flags & FAN_MARK_ONLYDIR)
 477                         lookup_flags |= LOOKUP_DIRECTORY;
 478
 479                 ret = user_path_at(dfd, filename, lookup_flags, path);
 480                 if (ret)
 481                         goto out;
 482         }
 483
 484         /* you can only watch an inode if you have read permissions on it */
 485         ret = inode_permission(path->dentry->d_inode, MAY_READ);
 486         if (ret)
 487                 path_put(path);
 488 out:
 489         return ret;
 490 }
 491
 492 static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
 493                                             __u32 mask,
 494                                             unsigned int flags)
 495 {
 496         __u32 oldmask;
 497
 498         spin_lock(&fsn_mark->lock);
 499         if (!(flags & FAN_MARK_IGNORED_MASK)) {
 500                 oldmask = fsn_mark->mask;
 501                 fsnotify_set_mark_mask_locked(fsn_mark, (oldmask & ~mask));
 502         } else {
 503                 oldmask = fsn_mark->ignored_mask;
 504                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, (oldmask & ~mask));
 505         }
 506         spin_unlock(&fsn_mark->lock);
 507
 508         if (!(oldmask & ~mask))
 509                 fsnotify_destroy_mark(fsn_mark);
 510
 511         return mask & oldmask;
 512 }
 513
 514 static 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
 521         fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
 522         if (!fsn_mark)
 523                 return -ENOENT;
 524
 525         removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags);
 526         fsnotify_put_mark(fsn_mark);
 527         if (removed & real_mount(mnt)->mnt_fsnotify_mask)
 528                 fsnotify_recalc_vfsmount_mask(mnt);
 529
 530         return 0;
 531 }
 532
 533 static int fanotify_remove_inode_mark(struct fsnotify_group *group,
 534                                       struct inode *inode, __u32 mask,
 535                                       unsigned int flags)
 536 {
 537         struct fsnotify_mark *fsn_mark = NULL;
 538         __u32 removed;
 539
 540         fsn_mark = fsnotify_find_inode_mark(group, inode);
 541         if (!fsn_mark)
 542                 return -ENOENT;
 543
 544         removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags);
 545         /* matches the fsnotify_find_inode_mark() */
 546         fsnotify_put_mark(fsn_mark);
 547         if (removed & inode->i_fsnotify_mask)
 548                 fsnotify_recalc_inode_mask(inode);
 549
 550         return 0;
 551 }
 552
 553 static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
 554                                        __u32 mask,
 555                                        unsigned int flags)
 556 {
 557         __u32 oldmask = -1;
 558
 559         spin_lock(&fsn_mark->lock);
 560         if (!(flags & FAN_MARK_IGNORED_MASK)) {
 561                 oldmask = fsn_mark->mask;
 562                 fsnotify_set_mark_mask_locked(fsn_mark, (oldmask | mask));
 563         } else {
 564                 __u32 tmask = fsn_mark->ignored_mask | mask;
 565                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
 566                 if (flags & FAN_MARK_IGNORED_SURV_MODIFY)
 567                         fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
 568         }
 569
 570         if (!(flags & FAN_MARK_ONDIR)) {
 571                 __u32 tmask = fsn_mark->ignored_mask | FAN_ONDIR;
 572                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
 573         }
 574
 575         spin_unlock(&fsn_mark->lock);
 576
 577         return mask & ~oldmask;
 578 }
 579
 580 static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
 581                                       struct vfsmount *mnt, __u32 mask,
 582                                       unsigned int flags)
 583 {
 584         struct fsnotify_mark *fsn_mark;
 585         __u32 added;
 586         int ret = 0;
 587
 588         fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
 589         if (!fsn_mark) {
 590                 if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
 591                         return -ENOSPC;
 592
 593                 fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
 594                 if (!fsn_mark)
 595                         return -ENOMEM;
 596
 597                 fsnotify_init_mark(fsn_mark, fanotify_free_mark);
 598                 ret = fsnotify_add_mark(fsn_mark, group, NULL, mnt, 0);
 599                 if (ret)
 600                         goto err;
 601         }
 602         added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
 603
 604         if (added & ~real_mount(mnt)->mnt_fsnotify_mask)
 605                 fsnotify_recalc_vfsmount_mask(mnt);
 606 err:
 607         fsnotify_put_mark(fsn_mark);
 608         return ret;
 609 }
 610
 611 static int fanotify_add_inode_mark(struct fsnotify_group *group,
 612                                    struct inode *inode, __u32 mask,
 613                                    unsigned int flags)
 614 {
 615         struct fsnotify_mark *fsn_mark;
 616         __u32 added;
 617         int ret = 0;
 618
 619         pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
 620
 621         /*
 622          * If some other task has this inode open for write we should not add
 623          * an ignored mark, unless that ignored mark is supposed to survive
 624          * modification changes anyway.
 625          */
 626         if ((flags & FAN_MARK_IGNORED_MASK) &&
 627             !(flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
 628             (atomic_read(&inode->i_writecount) > 0))
 629                 return 0;
 630
 631         fsn_mark = fsnotify_find_inode_mark(group, inode);
 632         if (!fsn_mark) {
 633                 if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
 634                         return -ENOSPC;
 635
 636                 fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
 637                 if (!fsn_mark)
 638                         return -ENOMEM;
 639
 640                 fsnotify_init_mark(fsn_mark, fanotify_free_mark);
 641                 ret = fsnotify_add_mark(fsn_mark, group, inode, NULL, 0);
 642                 if (ret)
 643                         goto err;
 644         }
 645         added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
 646
 647         if (added & ~inode->i_fsnotify_mask)
 648                 fsnotify_recalc_inode_mask(inode);
 649 err:
 650         fsnotify_put_mark(fsn_mark);
 651         return ret;
 652 }
 653
 654 /* fanotify syscalls */
 655 SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 656 {
 657         struct fsnotify_group *group;
 658         int f_flags, fd;
 659         struct user_struct *user;
 660
 661         pr_debug("%s: flags=%d event_f_flags=%d\n",
 662                 __func__, flags, event_f_flags);
 663
 664         if (!capable(CAP_SYS_ADMIN))
 665                 return -EPERM;
 666
 667         if (flags & ~FAN_ALL_INIT_FLAGS)
 668                 return -EINVAL;
 669
 670         user = get_current_user();
 671         if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {
 672                 free_uid(user);
 673                 return -EMFILE;
 674         }
 675
 676         f_flags = O_RDWR | FMODE_NONOTIFY;
 677         if (flags & FAN_CLOEXEC)
 678                 f_flags |= O_CLOEXEC;
 679         if (flags & FAN_NONBLOCK)
 680                 f_flags |= O_NONBLOCK;
 681
 682         /* fsnotify_alloc_group takes a ref.  Dropped in fanotify_release */
 683         group = fsnotify_alloc_group(&fanotify_fsnotify_ops);
 684         if (IS_ERR(group)) {
 685                 free_uid(user);
 686                 return PTR_ERR(group);
 687         }
 688
 689         group->fanotify_data.user = user;
 690         atomic_inc(&user->fanotify_listeners);
 691
 692         group->fanotify_data.f_flags = event_f_flags;
 693 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 694         mutex_init(&group->fanotify_data.access_mutex);
 695         init_waitqueue_head(&group->fanotify_data.access_waitq);
 696         INIT_LIST_HEAD(&group->fanotify_data.access_list);
 697         atomic_set(&group->fanotify_data.bypass_perm, 0);
 698 #endif
 699         switch (flags & FAN_ALL_CLASS_BITS) {
 700         case FAN_CLASS_NOTIF:
 701                 group->priority = FS_PRIO_0;
 702                 break;
 703         case FAN_CLASS_CONTENT:
 704                 group->priority = FS_PRIO_1;
 705                 break;
 706         case FAN_CLASS_PRE_CONTENT:
 707                 group->priority = FS_PRIO_2;
 708                 break;
 709         default:
 710                 fd = -EINVAL;
 711                 goto out_put_group;
 712         }
 713
 714         if (flags & FAN_UNLIMITED_QUEUE) {
 715                 fd = -EPERM;
 716                 if (!capable(CAP_SYS_ADMIN))
 717                         goto out_put_group;
 718                 group->max_events = UINT_MAX;
 719         } else {
 720                 group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS;
 721         }
 722
 723         if (flags & FAN_UNLIMITED_MARKS) {
 724                 fd = -EPERM;
 725                 if (!capable(CAP_SYS_ADMIN))
 726                         goto out_put_group;
 727                 group->fanotify_data.max_marks = UINT_MAX;
 728         } else {
 729                 group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS;
 730         }
 731
 732         fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
 733         if (fd < 0)
 734                 goto out_put_group;
 735
 736         return fd;
 737
 738 out_put_group:
 739         fsnotify_put_group(group);
 740         return fd;
 741 }
 742
 743 SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
 744                               __u64 mask, int dfd,
 745                               const char  __user * pathname)
 746 {
 747         struct inode *inode = NULL;
 748         struct vfsmount *mnt = NULL;
 749         struct fsnotify_group *group;
 750         struct fd f;
 751         struct path path;
 752         int ret;
 753
 754         pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
 755                  __func__, fanotify_fd, flags, dfd, pathname, mask);
 756
 757         /* we only use the lower 32 bits as of right now. */
 758         if (mask & ((__u64)0xffffffff << 32))
 759                 return -EINVAL;
 760
 761         if (flags & ~FAN_ALL_MARK_FLAGS)
 762                 return -EINVAL;
 763         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
 764         case FAN_MARK_ADD:              /* fallthrough */
 765         case FAN_MARK_REMOVE:
 766                 if (!mask)
 767                         return -EINVAL;
 768         case FAN_MARK_FLUSH:
 769                 break;
 770         default:
 771                 return -EINVAL;
 772         }
 773
 774         if (mask & FAN_ONDIR) {
 775                 flags |= FAN_MARK_ONDIR;
 776                 mask &= ~FAN_ONDIR;
 777         }
 778
 779 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 780         if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD))
 781 #else
 782         if (mask & ~(FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD))
 783 #endif
 784                 return -EINVAL;
 785
 786         f = fdget(fanotify_fd);
 787         if (unlikely(!f.file))
 788                 return -EBADF;
 789
 790         /* verify that this is indeed an fanotify instance */
 791         ret = -EINVAL;
 792         if (unlikely(f.file->f_op != &fanotify_fops))
 793                 goto fput_and_out;
 794         group = f.file->private_data;
 795
 796         /*
 797          * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF.  These are not
 798          * allowed to set permissions events.
 799          */
 800         ret = -EINVAL;
 801         if (mask & FAN_ALL_PERM_EVENTS &&
 802             group->priority == FS_PRIO_0)
 803                 goto fput_and_out;
 804
 805         ret = fanotify_find_path(dfd, pathname, &path, flags);
 806         if (ret)
 807                 goto fput_and_out;
 808
 809         /* inode held in place by reference to path; group by fget on fd */
 810         if (!(flags & FAN_MARK_MOUNT))
 811                 inode = path.dentry->d_inode;
 812         else
 813                 mnt = path.mnt;
 814
 815         /* create/update an inode mark */
 816         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
 817         case FAN_MARK_ADD:
 818                 if (flags & FAN_MARK_MOUNT)
 819                         ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags);
 820                 else
 821                         ret = fanotify_add_inode_mark(group, inode, mask, flags);
 822                 break;
 823         case FAN_MARK_REMOVE:
 824                 if (flags & FAN_MARK_MOUNT)
 825                         ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags);
 826                 else
 827                         ret = fanotify_remove_inode_mark(group, inode, mask, flags);
 828                 break;
 829         case FAN_MARK_FLUSH:
 830                 if (flags & FAN_MARK_MOUNT)
 831                         fsnotify_clear_vfsmount_marks_by_group(group);
 832                 else
 833                         fsnotify_clear_inode_marks_by_group(group);
 834                 break;
 835         default:
 836                 ret = -EINVAL;
 837         }
 838
 839         path_put(&path);
 840 fput_and_out:
 841         fdput(f);
 842         return ret;
 843 }
 844
 845 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 846 asmlinkage long SyS_fanotify_mark(long fanotify_fd, long flags, __u64 mask,
 847                                   long dfd, long pathname)
 848 {
 849         return SYSC_fanotify_mark((int) fanotify_fd, (unsigned int) flags,
 850                                   mask, (int) dfd,
 851                                   (const char  __user *) pathname);
 852 }
 853 SYSCALL_ALIAS(sys_fanotify_mark, SyS_fanotify_mark);
 854 #endif
 855
 856 /*
 857  * fanotify_user_setup - Our initialization function.  Note that we cannot return
 858  * error because we have compiled-in VFS hooks.  So an (unlikely) failure here
 859  * must result in panic().
 860  */
 861 static int __init fanotify_user_setup(void)
 862 {
 863         fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC);
 864         fanotify_response_event_cache = KMEM_CACHE(fanotify_response_event,
 865                                                    SLAB_PANIC);
 866
 867         return 0;
 868 }
 869 device_initcall(fanotify_user_setup);