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 #define FANOTIFY_DEFAULT_MAX_EVENTS     16384
  20 #define FANOTIFY_DEFAULT_MAX_MARKS      8192
  21 #define FANOTIFY_DEFAULT_MAX_LISTENERS  128
  22
  23 extern const struct fsnotify_ops fanotify_fsnotify_ops;
  24
  25 static struct kmem_cache *fanotify_mark_cache __read_mostly;
  26 static struct kmem_cache *fanotify_response_event_cache __read_mostly;
  27
  28 struct fanotify_response_event {
  29         struct list_head list;
  30         __s32 fd;
  31         struct fsnotify_event *event;
  32 };
  33
  34 /*
  35  * Get an fsnotify notification event if one exists and is small
  36  * enough to fit in "count". Return an error pointer if the count
  37  * is not large enough.
  38  *
  39  * Called with the group->notification_mutex held.
  40  */
  41 static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
  42                                             size_t count)
  43 {
  44         BUG_ON(!mutex_is_locked(&group->notification_mutex));
  45
  46         pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
  47
  48         if (fsnotify_notify_queue_is_empty(group))
  49                 return NULL;
  50
  51         if (FAN_EVENT_METADATA_LEN > count)
  52                 return ERR_PTR(-EINVAL);
  53
  54         /* held the notification_mutex the whole time, so this is the
  55          * same event we peeked above */
  56         return fsnotify_remove_notify_event(group);
  57 }
  58
  59 static int create_fd(struct fsnotify_group *group, struct fsnotify_event *event)
  60 {
  61         int client_fd;
  62         struct dentry *dentry;
  63         struct vfsmount *mnt;
  64         struct file *new_file;
  65
  66         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
  67
  68         client_fd = get_unused_fd();
  69         if (client_fd < 0)
  70                 return client_fd;
  71
  72         if (event->data_type != FSNOTIFY_EVENT_PATH) {
  73                 WARN_ON(1);
  74                 put_unused_fd(client_fd);
  75                 return -EINVAL;
  76         }
  77
  78         /*
  79          * we need a new file handle for the userspace program so it can read even if it was
  80          * originally opened O_WRONLY.
  81          */
  82         dentry = dget(event->path.dentry);
  83         mnt = mntget(event->path.mnt);
  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 (dentry && mnt)
  87                 new_file = dentry_open(dentry, mnt,
  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                 fd_install(client_fd, 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 {
 113         int ret = 0;
 114
 115         pr_debug("%s: group=%p metadata=%p event=%p\n", __func__,
 116                  group, metadata, event);
 117
 118         metadata->event_len = FAN_EVENT_METADATA_LEN;
 119         metadata->metadata_len = FAN_EVENT_METADATA_LEN;
 120         metadata->vers = FANOTIFY_METADATA_VERSION;
 121         metadata->mask = event->mask & FAN_ALL_OUTGOING_EVENTS;
 122         metadata->pid = pid_vnr(event->tgid);
 123         if (unlikely(event->mask & FAN_Q_OVERFLOW))
 124                 metadata->fd = FAN_NOFD;
 125         else {
 126                 metadata->fd = create_fd(group, event);
 127                 if (metadata->fd < 0)
 128                         ret = metadata->fd;
 129         }
 130
 131         return ret;
 132 }
 133
 134 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 135 static struct fanotify_response_event *dequeue_re(struct fsnotify_group *group,
 136                                                   __s32 fd)
 137 {
 138         struct fanotify_response_event *re, *return_re = NULL;
 139
 140         mutex_lock(&group->fanotify_data.access_mutex);
 141         list_for_each_entry(re, &group->fanotify_data.access_list, list) {
 142                 if (re->fd != fd)
 143                         continue;
 144
 145                 list_del_init(&re->list);
 146                 return_re = re;
 147                 break;
 148         }
 149         mutex_unlock(&group->fanotify_data.access_mutex);
 150
 151         pr_debug("%s: found return_re=%p\n", __func__, return_re);
 152
 153         return return_re;
 154 }
 155
 156 static int process_access_response(struct fsnotify_group *group,
 157                                    struct fanotify_response *response_struct)
 158 {
 159         struct fanotify_response_event *re;
 160         __s32 fd = response_struct->fd;
 161         __u32 response = response_struct->response;
 162
 163         pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group,
 164                  fd, response);
 165         /*
 166          * make sure the response is valid, if invalid we do nothing and either
 167          * userspace can send a valid response or we will clean it up after the
 168          * timeout
 169          */
 170         switch (response) {
 171         case FAN_ALLOW:
 172         case FAN_DENY:
 173                 break;
 174         default:
 175                 return -EINVAL;
 176         }
 177
 178         if (fd < 0)
 179                 return -EINVAL;
 180
 181         re = dequeue_re(group, fd);
 182         if (!re)
 183                 return -ENOENT;
 184
 185         re->event->response = response;
 186
 187         wake_up(&group->fanotify_data.access_waitq);
 188
 189         kmem_cache_free(fanotify_response_event_cache, re);
 190
 191         return 0;
 192 }
 193
 194 static int prepare_for_access_response(struct fsnotify_group *group,
 195                                        struct fsnotify_event *event,
 196                                        __s32 fd)
 197 {
 198         struct fanotify_response_event *re;
 199
 200         if (!(event->mask & FAN_ALL_PERM_EVENTS))
 201                 return 0;
 202
 203         re = kmem_cache_alloc(fanotify_response_event_cache, GFP_KERNEL);
 204         if (!re)
 205                 return -ENOMEM;
 206
 207         re->event = event;
 208         re->fd = fd;
 209
 210         mutex_lock(&group->fanotify_data.access_mutex);
 211
 212         if (atomic_read(&group->fanotify_data.bypass_perm)) {
 213                 mutex_unlock(&group->fanotify_data.access_mutex);
 214                 kmem_cache_free(fanotify_response_event_cache, re);
 215                 event->response = FAN_ALLOW;
 216                 return 0;
 217         }
 218
 219         list_add_tail(&re->list, &group->fanotify_data.access_list);
 220         mutex_unlock(&group->fanotify_data.access_mutex);
 221
 222         return 0;
 223 }
 224
 225 static void remove_access_response(struct fsnotify_group *group,
 226                                    struct fsnotify_event *event,
 227                                    __s32 fd)
 228 {
 229         struct fanotify_response_event *re;
 230
 231         if (!(event->mask & FAN_ALL_PERM_EVENTS))
 232                 return;
 233
 234         re = dequeue_re(group, fd);
 235         if (!re)
 236                 return;
 237
 238         BUG_ON(re->event != event);
 239
 240         kmem_cache_free(fanotify_response_event_cache, re);
 241
 242         return;
 243 }
 244 #else
 245 static int prepare_for_access_response(struct fsnotify_group *group,
 246                                        struct fsnotify_event *event,
 247                                        __s32 fd)
 248 {
 249         return 0;
 250 }
 251
 252 static void remove_access_response(struct fsnotify_group *group,
 253                                    struct fsnotify_event *event,
 254                                    __s32 fd)
 255 {
 256         return;
 257 }
 258 #endif
 259
 260 static ssize_t copy_event_to_user(struct fsnotify_group *group,
 261                                   struct fsnotify_event *event,
 262                                   char __user *buf)
 263 {
 264         struct fanotify_event_metadata fanotify_event_metadata;
 265         int fd, ret;
 266
 267         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
 268
 269         ret = fill_event_metadata(group, &fanotify_event_metadata, event);
 270         if (ret < 0)
 271                 goto out;
 272
 273         fd = fanotify_event_metadata.fd;
 274         ret = prepare_for_access_response(group, event, fd);
 275         if (ret)
 276                 goto out_close_fd;
 277
 278         ret = -EFAULT;
 279         if (copy_to_user(buf, &fanotify_event_metadata,
 280                          fanotify_event_metadata.event_len))
 281                 goto out_kill_access_response;
 282
 283         return fanotify_event_metadata.event_len;
 284
 285 out_kill_access_response:
 286         remove_access_response(group, event, fd);
 287 out_close_fd:
 288         if (fd != FAN_NOFD)
 289                 sys_close(fd);
 290 out:
 291 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 292         if (event->mask & FAN_ALL_PERM_EVENTS) {
 293                 event->response = FAN_DENY;
 294                 wake_up(&group->fanotify_data.access_waitq);
 295         }
 296 #endif
 297         return ret;
 298 }
 299
 300 /* intofiy userspace file descriptor functions */
 301 static unsigned int fanotify_poll(struct file *file, poll_table *wait)
 302 {
 303         struct fsnotify_group *group = file->private_data;
 304         int ret = 0;
 305
 306         poll_wait(file, &group->notification_waitq, wait);
 307         mutex_lock(&group->notification_mutex);
 308         if (!fsnotify_notify_queue_is_empty(group))
 309                 ret = POLLIN | POLLRDNORM;
 310         mutex_unlock(&group->notification_mutex);
 311
 312         return ret;
 313 }
 314
 315 static ssize_t fanotify_read(struct file *file, char __user *buf,
 316                              size_t count, loff_t *pos)
 317 {
 318         struct fsnotify_group *group;
 319         struct fsnotify_event *kevent;
 320         char __user *start;
 321         int ret;
 322         DEFINE_WAIT(wait);
 323
 324         start = buf;
 325         group = file->private_data;
 326
 327         pr_debug("%s: group=%p\n", __func__, group);
 328
 329         while (1) {
 330                 prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE);
 331
 332                 mutex_lock(&group->notification_mutex);
 333                 kevent = get_one_event(group, count);
 334                 mutex_unlock(&group->notification_mutex);
 335
 336                 if (kevent) {
 337                         ret = PTR_ERR(kevent);
 338                         if (IS_ERR(kevent))
 339                                 break;
 340                         ret = copy_event_to_user(group, kevent, buf);
 341                         fsnotify_put_event(kevent);
 342                         if (ret < 0)
 343                                 break;
 344                         buf += ret;
 345                         count -= ret;
 346                         continue;
 347                 }
 348
 349                 ret = -EAGAIN;
 350                 if (file->f_flags & O_NONBLOCK)
 351                         break;
 352                 ret = -ERESTARTSYS;
 353                 if (signal_pending(current))
 354                         break;
 355
 356                 if (start != buf)
 357                         break;
 358
 359                 schedule();
 360         }
 361
 362         finish_wait(&group->notification_waitq, &wait);
 363         if (start != buf && ret != -EFAULT)
 364                 ret = buf - start;
 365         return ret;
 366 }
 367
 368 static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
 369 {
 370 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 371         struct fanotify_response response = { .fd = -1, .response = -1 };
 372         struct fsnotify_group *group;
 373         int ret;
 374
 375         group = file->private_data;
 376
 377         if (count > sizeof(response))
 378                 count = sizeof(response);
 379
 380         pr_debug("%s: group=%p count=%zu\n", __func__, group, count);
 381
 382         if (copy_from_user(&response, buf, count))
 383                 return -EFAULT;
 384
 385         ret = process_access_response(group, &response);
 386         if (ret < 0)
 387                 count = ret;
 388
 389         return count;
 390 #else
 391         return -EINVAL;
 392 #endif
 393 }
 394
 395 static int fanotify_release(struct inode *ignored, struct file *file)
 396 {
 397         struct fsnotify_group *group = file->private_data;
 398
 399 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 400         struct fanotify_response_event *re, *lre;
 401
 402         mutex_lock(&group->fanotify_data.access_mutex);
 403
 404         atomic_inc(&group->fanotify_data.bypass_perm);
 405
 406         list_for_each_entry_safe(re, lre, &group->fanotify_data.access_list, list) {
 407                 pr_debug("%s: found group=%p re=%p event=%p\n", __func__, group,
 408                          re, re->event);
 409
 410                 list_del_init(&re->list);
 411                 re->event->response = FAN_ALLOW;
 412
 413                 kmem_cache_free(fanotify_response_event_cache, re);
 414         }
 415         mutex_unlock(&group->fanotify_data.access_mutex);
 416
 417         wake_up(&group->fanotify_data.access_waitq);
 418 #endif
 419         /* matches the fanotify_init->fsnotify_alloc_group */
 420         fsnotify_put_group(group);
 421
 422         return 0;
 423 }
 424
 425 static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 426 {
 427         struct fsnotify_group *group;
 428         struct fsnotify_event_holder *holder;
 429         void __user *p;
 430         int ret = -ENOTTY;
 431         size_t send_len = 0;
 432
 433         group = file->private_data;
 434
 435         p = (void __user *) arg;
 436
 437         switch (cmd) {
 438         case FIONREAD:
 439                 mutex_lock(&group->notification_mutex);
 440                 list_for_each_entry(holder, &group->notification_list, event_list)
 441                         send_len += FAN_EVENT_METADATA_LEN;
 442                 mutex_unlock(&group->notification_mutex);
 443                 ret = put_user(send_len, (int __user *) p);
 444                 break;
 445         }
 446
 447         return ret;
 448 }
 449
 450 static const struct file_operations fanotify_fops = {
 451         .poll           = fanotify_poll,
 452         .read           = fanotify_read,
 453         .write          = fanotify_write,
 454         .fasync         = NULL,
 455         .release        = fanotify_release,
 456         .unlocked_ioctl = fanotify_ioctl,
 457         .compat_ioctl   = fanotify_ioctl,
 458         .llseek         = noop_llseek,
 459 };
 460
 461 static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
 462 {
 463         kmem_cache_free(fanotify_mark_cache, fsn_mark);
 464 }
 465
 466 static int fanotify_find_path(int dfd, const char __user *filename,
 467                               struct path *path, unsigned int flags)
 468 {
 469         int ret;
 470
 471         pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__,
 472                  dfd, filename, flags);
 473
 474         if (filename == NULL) {
 475                 struct file *file;
 476                 int fput_needed;
 477
 478                 ret = -EBADF;
 479                 file = fget_light(dfd, &fput_needed);
 480                 if (!file)
 481                         goto out;
 482
 483                 ret = -ENOTDIR;
 484                 if ((flags & FAN_MARK_ONLYDIR) &&
 485                     !(S_ISDIR(file->f_path.dentry->d_inode->i_mode))) {
 486                         fput_light(file, fput_needed);
 487                         goto out;
 488                 }
 489
 490                 *path = file->f_path;
 491                 path_get(path);
 492                 fput_light(file, fput_needed);
 493         } else {
 494                 unsigned int lookup_flags = 0;
 495
 496                 if (!(flags & FAN_MARK_DONT_FOLLOW))
 497                         lookup_flags |= LOOKUP_FOLLOW;
 498                 if (flags & FAN_MARK_ONLYDIR)
 499                         lookup_flags |= LOOKUP_DIRECTORY;
 500
 501                 ret = user_path_at(dfd, filename, lookup_flags, path);
 502                 if (ret)
 503                         goto out;
 504         }
 505
 506         /* you can only watch an inode if you have read permissions on it */
 507         ret = inode_permission(path->dentry->d_inode, MAY_READ);
 508         if (ret)
 509                 path_put(path);
 510 out:
 511         return ret;
 512 }
 513
 514 static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
 515                                             __u32 mask,
 516                                             unsigned int flags)
 517 {
 518         __u32 oldmask;
 519
 520         spin_lock(&fsn_mark->lock);
 521         if (!(flags & FAN_MARK_IGNORED_MASK)) {
 522                 oldmask = fsn_mark->mask;
 523                 fsnotify_set_mark_mask_locked(fsn_mark, (oldmask & ~mask));
 524         } else {
 525                 oldmask = fsn_mark->ignored_mask;
 526                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, (oldmask & ~mask));
 527         }
 528         spin_unlock(&fsn_mark->lock);
 529
 530         if (!(oldmask & ~mask))
 531                 fsnotify_destroy_mark(fsn_mark);
 532
 533         return mask & oldmask;
 534 }
 535
 536 static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
 537                                          struct vfsmount *mnt, __u32 mask,
 538                                          unsigned int flags)
 539 {
 540         struct fsnotify_mark *fsn_mark = NULL;
 541         __u32 removed;
 542
 543         fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
 544         if (!fsn_mark)
 545                 return -ENOENT;
 546
 547         removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags);
 548         fsnotify_put_mark(fsn_mark);
 549         if (removed & mnt->mnt_fsnotify_mask)
 550                 fsnotify_recalc_vfsmount_mask(mnt);
 551
 552         return 0;
 553 }
 554
 555 static int fanotify_remove_inode_mark(struct fsnotify_group *group,
 556                                       struct inode *inode, __u32 mask,
 557                                       unsigned int flags)
 558 {
 559         struct fsnotify_mark *fsn_mark = NULL;
 560         __u32 removed;
 561
 562         fsn_mark = fsnotify_find_inode_mark(group, inode);
 563         if (!fsn_mark)
 564                 return -ENOENT;
 565
 566         removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags);
 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
 575 static __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                 oldmask = fsn_mark->mask;
 584                 fsnotify_set_mark_mask_locked(fsn_mark, (oldmask | mask));
 585         } else {
 586                 __u32 tmask = fsn_mark->ignored_mask | mask;
 587                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
 588                 if (flags & FAN_MARK_IGNORED_SURV_MODIFY)
 589                         fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
 590         }
 591
 592         if (!(flags & FAN_MARK_ONDIR)) {
 593                 __u32 tmask = fsn_mark->ignored_mask | FAN_ONDIR;
 594                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
 595         }
 596
 597         spin_unlock(&fsn_mark->lock);
 598
 599         return mask & ~oldmask;
 600 }
 601
 602 static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
 603                                       struct vfsmount *mnt, __u32 mask,
 604                                       unsigned int flags)
 605 {
 606         struct fsnotify_mark *fsn_mark;
 607         __u32 added;
 608         int ret = 0;
 609
 610         fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
 611         if (!fsn_mark) {
 612                 if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
 613                         return -ENOSPC;
 614
 615                 fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
 616                 if (!fsn_mark)
 617                         return -ENOMEM;
 618
 619                 fsnotify_init_mark(fsn_mark, fanotify_free_mark);
 620                 ret = fsnotify_add_mark(fsn_mark, group, NULL, mnt, 0);
 621                 if (ret)
 622                         goto err;
 623         }
 624         added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
 625
 626         if (added & ~mnt->mnt_fsnotify_mask)
 627                 fsnotify_recalc_vfsmount_mask(mnt);
 628 err:
 629         fsnotify_put_mark(fsn_mark);
 630         return ret;
 631 }
 632
 633 static int fanotify_add_inode_mark(struct fsnotify_group *group,
 634                                    struct inode *inode, __u32 mask,
 635                                    unsigned int flags)
 636 {
 637         struct fsnotify_mark *fsn_mark;
 638         __u32 added;
 639         int ret = 0;
 640
 641         pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
 642
 643         /*
 644          * If some other task has this inode open for write we should not add
 645          * an ignored mark, unless that ignored mark is supposed to survive
 646          * modification changes anyway.
 647          */
 648         if ((flags & FAN_MARK_IGNORED_MASK) &&
 649             !(flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
 650             (atomic_read(&inode->i_writecount) > 0))
 651                 return 0;
 652
 653         fsn_mark = fsnotify_find_inode_mark(group, inode);
 654         if (!fsn_mark) {
 655                 if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
 656                         return -ENOSPC;
 657
 658                 fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
 659                 if (!fsn_mark)
 660                         return -ENOMEM;
 661
 662                 fsnotify_init_mark(fsn_mark, fanotify_free_mark);
 663                 ret = fsnotify_add_mark(fsn_mark, group, inode, NULL, 0);
 664                 if (ret)
 665                         goto err;
 666         }
 667         added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
 668
 669         if (added & ~inode->i_fsnotify_mask)
 670                 fsnotify_recalc_inode_mask(inode);
 671 err:
 672         fsnotify_put_mark(fsn_mark);
 673         return ret;
 674 }
 675
 676 /* fanotify syscalls */
 677 SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 678 {
 679         struct fsnotify_group *group;
 680         int f_flags, fd;
 681         struct user_struct *user;
 682
 683         pr_debug("%s: flags=%d event_f_flags=%d\n",
 684                 __func__, flags, event_f_flags);
 685
 686         if (!capable(CAP_SYS_ADMIN))
 687                 return -EPERM;
 688
 689         if (flags & ~FAN_ALL_INIT_FLAGS)
 690                 return -EINVAL;
 691
 692         user = get_current_user();
 693         if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {
 694                 free_uid(user);
 695                 return -EMFILE;
 696         }
 697
 698         f_flags = O_RDWR | FMODE_NONOTIFY;
 699         if (flags & FAN_CLOEXEC)
 700                 f_flags |= O_CLOEXEC;
 701         if (flags & FAN_NONBLOCK)
 702                 f_flags |= O_NONBLOCK;
 703
 704         /* fsnotify_alloc_group takes a ref.  Dropped in fanotify_release */
 705         group = fsnotify_alloc_group(&fanotify_fsnotify_ops);
 706         if (IS_ERR(group)) {
 707                 free_uid(user);
 708                 return PTR_ERR(group);
 709         }
 710
 711         group->fanotify_data.user = user;
 712         atomic_inc(&user->fanotify_listeners);
 713
 714         group->fanotify_data.f_flags = event_f_flags;
 715 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 716         mutex_init(&group->fanotify_data.access_mutex);
 717         init_waitqueue_head(&group->fanotify_data.access_waitq);
 718         INIT_LIST_HEAD(&group->fanotify_data.access_list);
 719         atomic_set(&group->fanotify_data.bypass_perm, 0);
 720 #endif
 721         switch (flags & FAN_ALL_CLASS_BITS) {
 722         case FAN_CLASS_NOTIF:
 723                 group->priority = FS_PRIO_0;
 724                 break;
 725         case FAN_CLASS_CONTENT:
 726                 group->priority = FS_PRIO_1;
 727                 break;
 728         case FAN_CLASS_PRE_CONTENT:
 729                 group->priority = FS_PRIO_2;
 730                 break;
 731         default:
 732                 fd = -EINVAL;
 733                 goto out_put_group;
 734         }
 735
 736         if (flags & FAN_UNLIMITED_QUEUE) {
 737                 fd = -EPERM;
 738                 if (!capable(CAP_SYS_ADMIN))
 739                         goto out_put_group;
 740                 group->max_events = UINT_MAX;
 741         } else {
 742                 group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS;
 743         }
 744
 745         if (flags & FAN_UNLIMITED_MARKS) {
 746                 fd = -EPERM;
 747                 if (!capable(CAP_SYS_ADMIN))
 748                         goto out_put_group;
 749                 group->fanotify_data.max_marks = UINT_MAX;
 750         } else {
 751                 group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS;
 752         }
 753
 754         fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
 755         if (fd < 0)
 756                 goto out_put_group;
 757
 758         return fd;
 759
 760 out_put_group:
 761         fsnotify_put_group(group);
 762         return fd;
 763 }
 764
 765 SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
 766                               __u64 mask, int dfd,
 767                               const char  __user * pathname)
 768 {
 769         struct inode *inode = NULL;
 770         struct vfsmount *mnt = NULL;
 771         struct fsnotify_group *group;
 772         struct file *filp;
 773         struct path path;
 774         int ret, fput_needed;
 775
 776         pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
 777                  __func__, fanotify_fd, flags, dfd, pathname, mask);
 778
 779         /* we only use the lower 32 bits as of right now. */
 780         if (mask & ((__u64)0xffffffff << 32))
 781                 return -EINVAL;
 782
 783         if (flags & ~FAN_ALL_MARK_FLAGS)
 784                 return -EINVAL;
 785         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
 786         case FAN_MARK_ADD:              /* fallthrough */
 787         case FAN_MARK_REMOVE:
 788                 if (!mask)
 789                         return -EINVAL;
 790         case FAN_MARK_FLUSH:
 791                 break;
 792         default:
 793                 return -EINVAL;
 794         }
 795
 796         if (mask & FAN_ONDIR) {
 797                 flags |= FAN_MARK_ONDIR;
 798                 mask &= ~FAN_ONDIR;
 799         }
 800
 801 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 802         if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD))
 803 #else
 804         if (mask & ~(FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD))
 805 #endif
 806                 return -EINVAL;
 807
 808         filp = fget_light(fanotify_fd, &fput_needed);
 809         if (unlikely(!filp))
 810                 return -EBADF;
 811
 812         /* verify that this is indeed an fanotify instance */
 813         ret = -EINVAL;
 814         if (unlikely(filp->f_op != &fanotify_fops))
 815                 goto fput_and_out;
 816         group = filp->private_data;
 817
 818         /*
 819          * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF.  These are not
 820          * allowed to set permissions events.
 821          */
 822         ret = -EINVAL;
 823         if (mask & FAN_ALL_PERM_EVENTS &&
 824             group->priority == FS_PRIO_0)
 825                 goto fput_and_out;
 826
 827         ret = fanotify_find_path(dfd, pathname, &path, flags);
 828         if (ret)
 829                 goto fput_and_out;
 830
 831         /* inode held in place by reference to path; group by fget on fd */
 832         if (!(flags & FAN_MARK_MOUNT))
 833                 inode = path.dentry->d_inode;
 834         else
 835                 mnt = path.mnt;
 836
 837         /* create/update an inode mark */
 838         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
 839         case FAN_MARK_ADD:
 840                 if (flags & FAN_MARK_MOUNT)
 841                         ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags);
 842                 else
 843                         ret = fanotify_add_inode_mark(group, inode, mask, flags);
 844                 break;
 845         case FAN_MARK_REMOVE:
 846                 if (flags & FAN_MARK_MOUNT)
 847                         ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags);
 848                 else
 849                         ret = fanotify_remove_inode_mark(group, inode, mask, flags);
 850                 break;
 851         case FAN_MARK_FLUSH:
 852                 if (flags & FAN_MARK_MOUNT)
 853                         fsnotify_clear_vfsmount_marks_by_group(group);
 854                 else
 855                         fsnotify_clear_inode_marks_by_group(group);
 856                 break;
 857         default:
 858                 ret = -EINVAL;
 859         }
 860
 861         path_put(&path);
 862 fput_and_out:
 863         fput_light(filp, fput_needed);
 864         return ret;
 865 }
 866
 867 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 868 asmlinkage long SyS_fanotify_mark(long fanotify_fd, long flags, __u64 mask,
 869                                   long dfd, long pathname)
 870 {
 871         return SYSC_fanotify_mark((int) fanotify_fd, (unsigned int) flags,
 872                                   mask, (int) dfd,
 873                                   (const char  __user *) pathname);
 874 }
 875 SYSCALL_ALIAS(sys_fanotify_mark, SyS_fanotify_mark);
 876 #endif
 877
 878 /*
 879  * fanotify_user_setup - Our initialization function.  Note that we cannot return
 880  * error because we have compiled-in VFS hooks.  So an (unlikely) failure here
 881  * must result in panic().
 882  */
 883 static int __init fanotify_user_setup(void)
 884 {
 885         fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC);
 886         fanotify_response_event_cache = KMEM_CACHE(fanotify_response_event,
 887                                                    SLAB_PANIC);
 888
 889         return 0;
 890 }
 891 device_initcall(fanotify_user_setup);