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, struct fsnotify_event *event)
  62 {
  63         int client_fd;
  64         struct dentry *dentry;
  65         struct vfsmount *mnt;
  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         dentry = dget(event->path.dentry);
  85         mnt = mntget(event->path.mnt);
  86         /* it's possible this event was an overflow event.  in that case dentry and mnt
  87          * are NULL;  That's fine, just don't call dentry open */
  88         if (dentry && mnt)
  89                 new_file = dentry_open(dentry, mnt,
  90                                        group->fanotify_data.f_flags | FMODE_NONOTIFY,
  91                                        current_cred());
  92         else
  93                 new_file = ERR_PTR(-EOVERFLOW);
  94         if (IS_ERR(new_file)) {
  95                 /*
  96                  * we still send an event even if we can't open the file.  this
  97                  * can happen when say tasks are gone and we try to open their
  98                  * /proc files or we try to open a WRONLY file like in sysfs
  99                  * we just send the errno to userspace since there isn't much
 100                  * else we can do.
 101                  */
 102                 put_unused_fd(client_fd);
 103                 client_fd = PTR_ERR(new_file);
 104         } else {
 105                 fd_install(client_fd, new_file);
 106         }
 107
 108         return client_fd;
 109 }
 110
 111 static int fill_event_metadata(struct fsnotify_group *group,
 112                                    struct fanotify_event_metadata *metadata,
 113                                    struct fsnotify_event *event)
 114 {
 115         int ret = 0;
 116
 117         pr_debug("%s: group=%p metadata=%p event=%p\n", __func__,
 118                  group, metadata, event);
 119
 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);
 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 static void remove_access_response(struct fsnotify_group *group,
 228                                    struct fsnotify_event *event,
 229                                    __s32 fd)
 230 {
 231         struct fanotify_response_event *re;
 232
 233         if (!(event->mask & FAN_ALL_PERM_EVENTS))
 234                 return;
 235
 236         re = dequeue_re(group, fd);
 237         if (!re)
 238                 return;
 239
 240         BUG_ON(re->event != event);
 241
 242         kmem_cache_free(fanotify_response_event_cache, re);
 243
 244         return;
 245 }
 246 #else
 247 static int prepare_for_access_response(struct fsnotify_group *group,
 248                                        struct fsnotify_event *event,
 249                                        __s32 fd)
 250 {
 251         return 0;
 252 }
 253
 254 static void remove_access_response(struct fsnotify_group *group,
 255                                    struct fsnotify_event *event,
 256                                    __s32 fd)
 257 {
 258         return;
 259 }
 260 #endif
 261
 262 static ssize_t copy_event_to_user(struct fsnotify_group *group,
 263                                   struct fsnotify_event *event,
 264                                   char __user *buf)
 265 {
 266         struct fanotify_event_metadata fanotify_event_metadata;
 267         int fd, ret;
 268
 269         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
 270
 271         ret = fill_event_metadata(group, &fanotify_event_metadata, event);
 272         if (ret < 0)
 273                 goto out;
 274
 275         fd = fanotify_event_metadata.fd;
 276         ret = prepare_for_access_response(group, event, fd);
 277         if (ret)
 278                 goto out_close_fd;
 279
 280         ret = -EFAULT;
 281         if (copy_to_user(buf, &fanotify_event_metadata,
 282                          fanotify_event_metadata.event_len))
 283                 goto out_kill_access_response;
 284
 285         return fanotify_event_metadata.event_len;
 286
 287 out_kill_access_response:
 288         remove_access_response(group, event, fd);
 289 out_close_fd:
 290         if (fd != FAN_NOFD)
 291                 sys_close(fd);
 292 out:
 293 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 294         if (event->mask & FAN_ALL_PERM_EVENTS) {
 295                 event->response = FAN_DENY;
 296                 wake_up(&group->fanotify_data.access_waitq);
 297         }
 298 #endif
 299         return ret;
 300 }
 301
 302 /* intofiy userspace file descriptor functions */
 303 static unsigned int fanotify_poll(struct file *file, poll_table *wait)
 304 {
 305         struct fsnotify_group *group = file->private_data;
 306         int ret = 0;
 307
 308         poll_wait(file, &group->notification_waitq, wait);
 309         mutex_lock(&group->notification_mutex);
 310         if (!fsnotify_notify_queue_is_empty(group))
 311                 ret = POLLIN | POLLRDNORM;
 312         mutex_unlock(&group->notification_mutex);
 313
 314         return ret;
 315 }
 316
 317 static ssize_t fanotify_read(struct file *file, char __user *buf,
 318                              size_t count, loff_t *pos)
 319 {
 320         struct fsnotify_group *group;
 321         struct fsnotify_event *kevent;
 322         char __user *start;
 323         int ret;
 324         DEFINE_WAIT(wait);
 325
 326         start = buf;
 327         group = file->private_data;
 328
 329         pr_debug("%s: group=%p\n", __func__, group);
 330
 331         while (1) {
 332                 prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE);
 333
 334                 mutex_lock(&group->notification_mutex);
 335                 kevent = get_one_event(group, count);
 336                 mutex_unlock(&group->notification_mutex);
 337
 338                 if (kevent) {
 339                         ret = PTR_ERR(kevent);
 340                         if (IS_ERR(kevent))
 341                                 break;
 342                         ret = copy_event_to_user(group, kevent, buf);
 343                         fsnotify_put_event(kevent);
 344                         if (ret < 0)
 345                                 break;
 346                         buf += ret;
 347                         count -= ret;
 348                         continue;
 349                 }
 350
 351                 ret = -EAGAIN;
 352                 if (file->f_flags & O_NONBLOCK)
 353                         break;
 354                 ret = -ERESTARTSYS;
 355                 if (signal_pending(current))
 356                         break;
 357
 358                 if (start != buf)
 359                         break;
 360
 361                 schedule();
 362         }
 363
 364         finish_wait(&group->notification_waitq, &wait);
 365         if (start != buf && ret != -EFAULT)
 366                 ret = buf - start;
 367         return ret;
 368 }
 369
 370 static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
 371 {
 372 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 373         struct fanotify_response response = { .fd = -1, .response = -1 };
 374         struct fsnotify_group *group;
 375         int ret;
 376
 377         group = file->private_data;
 378
 379         if (count > sizeof(response))
 380                 count = sizeof(response);
 381
 382         pr_debug("%s: group=%p count=%zu\n", __func__, group, count);
 383
 384         if (copy_from_user(&response, buf, count))
 385                 return -EFAULT;
 386
 387         ret = process_access_response(group, &response);
 388         if (ret < 0)
 389                 count = ret;
 390
 391         return count;
 392 #else
 393         return -EINVAL;
 394 #endif
 395 }
 396
 397 static int fanotify_release(struct inode *ignored, struct file *file)
 398 {
 399         struct fsnotify_group *group = file->private_data;
 400
 401 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 402         struct fanotify_response_event *re, *lre;
 403
 404         mutex_lock(&group->fanotify_data.access_mutex);
 405
 406         atomic_inc(&group->fanotify_data.bypass_perm);
 407
 408         list_for_each_entry_safe(re, lre, &group->fanotify_data.access_list, list) {
 409                 pr_debug("%s: found group=%p re=%p event=%p\n", __func__, group,
 410                          re, re->event);
 411
 412                 list_del_init(&re->list);
 413                 re->event->response = FAN_ALLOW;
 414
 415                 kmem_cache_free(fanotify_response_event_cache, re);
 416         }
 417         mutex_unlock(&group->fanotify_data.access_mutex);
 418
 419         wake_up(&group->fanotify_data.access_waitq);
 420 #endif
 421         /* matches the fanotify_init->fsnotify_alloc_group */
 422         fsnotify_put_group(group);
 423
 424         return 0;
 425 }
 426
 427 static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 428 {
 429         struct fsnotify_group *group;
 430         struct fsnotify_event_holder *holder;
 431         void __user *p;
 432         int ret = -ENOTTY;
 433         size_t send_len = 0;
 434
 435         group = file->private_data;
 436
 437         p = (void __user *) arg;
 438
 439         switch (cmd) {
 440         case FIONREAD:
 441                 mutex_lock(&group->notification_mutex);
 442                 list_for_each_entry(holder, &group->notification_list, event_list)
 443                         send_len += FAN_EVENT_METADATA_LEN;
 444                 mutex_unlock(&group->notification_mutex);
 445                 ret = put_user(send_len, (int __user *) p);
 446                 break;
 447         }
 448
 449         return ret;
 450 }
 451
 452 static const struct file_operations fanotify_fops = {
 453         .poll           = fanotify_poll,
 454         .read           = fanotify_read,
 455         .write          = fanotify_write,
 456         .fasync         = NULL,
 457         .release        = fanotify_release,
 458         .unlocked_ioctl = fanotify_ioctl,
 459         .compat_ioctl   = fanotify_ioctl,
 460         .llseek         = noop_llseek,
 461 };
 462
 463 static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
 464 {
 465         kmem_cache_free(fanotify_mark_cache, fsn_mark);
 466 }
 467
 468 static int fanotify_find_path(int dfd, const char __user *filename,
 469                               struct path *path, unsigned int flags)
 470 {
 471         int ret;
 472
 473         pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__,
 474                  dfd, filename, flags);
 475
 476         if (filename == NULL) {
 477                 struct file *file;
 478                 int fput_needed;
 479
 480                 ret = -EBADF;
 481                 file = fget_light(dfd, &fput_needed);
 482                 if (!file)
 483                         goto out;
 484
 485                 ret = -ENOTDIR;
 486                 if ((flags & FAN_MARK_ONLYDIR) &&
 487                     !(S_ISDIR(file->f_path.dentry->d_inode->i_mode))) {
 488                         fput_light(file, fput_needed);
 489                         goto out;
 490                 }
 491
 492                 *path = file->f_path;
 493                 path_get(path);
 494                 fput_light(file, fput_needed);
 495         } else {
 496                 unsigned int lookup_flags = 0;
 497
 498                 if (!(flags & FAN_MARK_DONT_FOLLOW))
 499                         lookup_flags |= LOOKUP_FOLLOW;
 500                 if (flags & FAN_MARK_ONLYDIR)
 501                         lookup_flags |= LOOKUP_DIRECTORY;
 502
 503                 ret = user_path_at(dfd, filename, lookup_flags, path);
 504                 if (ret)
 505                         goto out;
 506         }
 507
 508         /* you can only watch an inode if you have read permissions on it */
 509         ret = inode_permission(path->dentry->d_inode, MAY_READ);
 510         if (ret)
 511                 path_put(path);
 512 out:
 513         return ret;
 514 }
 515
 516 static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
 517                                             __u32 mask,
 518                                             unsigned int flags)
 519 {
 520         __u32 oldmask;
 521
 522         spin_lock(&fsn_mark->lock);
 523         if (!(flags & FAN_MARK_IGNORED_MASK)) {
 524                 oldmask = fsn_mark->mask;
 525                 fsnotify_set_mark_mask_locked(fsn_mark, (oldmask & ~mask));
 526         } else {
 527                 oldmask = fsn_mark->ignored_mask;
 528                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, (oldmask & ~mask));
 529         }
 530         spin_unlock(&fsn_mark->lock);
 531
 532         if (!(oldmask & ~mask))
 533                 fsnotify_destroy_mark(fsn_mark);
 534
 535         return mask & oldmask;
 536 }
 537
 538 static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
 539                                          struct vfsmount *mnt, __u32 mask,
 540                                          unsigned int flags)
 541 {
 542         struct fsnotify_mark *fsn_mark = NULL;
 543         __u32 removed;
 544
 545         fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
 546         if (!fsn_mark)
 547                 return -ENOENT;
 548
 549         removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags);
 550         fsnotify_put_mark(fsn_mark);
 551         if (removed & real_mount(mnt)->mnt_fsnotify_mask)
 552                 fsnotify_recalc_vfsmount_mask(mnt);
 553
 554         return 0;
 555 }
 556
 557 static int fanotify_remove_inode_mark(struct fsnotify_group *group,
 558                                       struct inode *inode, __u32 mask,
 559                                       unsigned int flags)
 560 {
 561         struct fsnotify_mark *fsn_mark = NULL;
 562         __u32 removed;
 563
 564         fsn_mark = fsnotify_find_inode_mark(group, inode);
 565         if (!fsn_mark)
 566                 return -ENOENT;
 567
 568         removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags);
 569         /* matches the fsnotify_find_inode_mark() */
 570         fsnotify_put_mark(fsn_mark);
 571         if (removed & inode->i_fsnotify_mask)
 572                 fsnotify_recalc_inode_mask(inode);
 573
 574         return 0;
 575 }
 576
 577 static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
 578                                        __u32 mask,
 579                                        unsigned int flags)
 580 {
 581         __u32 oldmask = -1;
 582
 583         spin_lock(&fsn_mark->lock);
 584         if (!(flags & FAN_MARK_IGNORED_MASK)) {
 585                 oldmask = fsn_mark->mask;
 586                 fsnotify_set_mark_mask_locked(fsn_mark, (oldmask | mask));
 587         } else {
 588                 __u32 tmask = fsn_mark->ignored_mask | mask;
 589                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
 590                 if (flags & FAN_MARK_IGNORED_SURV_MODIFY)
 591                         fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
 592         }
 593
 594         if (!(flags & FAN_MARK_ONDIR)) {
 595                 __u32 tmask = fsn_mark->ignored_mask | FAN_ONDIR;
 596                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
 597         }
 598
 599         spin_unlock(&fsn_mark->lock);
 600
 601         return mask & ~oldmask;
 602 }
 603
 604 static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
 605                                       struct vfsmount *mnt, __u32 mask,
 606                                       unsigned int flags)
 607 {
 608         struct fsnotify_mark *fsn_mark;
 609         __u32 added;
 610         int ret = 0;
 611
 612         fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
 613         if (!fsn_mark) {
 614                 if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
 615                         return -ENOSPC;
 616
 617                 fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
 618                 if (!fsn_mark)
 619                         return -ENOMEM;
 620
 621                 fsnotify_init_mark(fsn_mark, fanotify_free_mark);
 622                 ret = fsnotify_add_mark(fsn_mark, group, NULL, mnt, 0);
 623                 if (ret)
 624                         goto err;
 625         }
 626         added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
 627
 628         if (added & ~real_mount(mnt)->mnt_fsnotify_mask)
 629                 fsnotify_recalc_vfsmount_mask(mnt);
 630 err:
 631         fsnotify_put_mark(fsn_mark);
 632         return ret;
 633 }
 634
 635 static int fanotify_add_inode_mark(struct fsnotify_group *group,
 636                                    struct inode *inode, __u32 mask,
 637                                    unsigned int flags)
 638 {
 639         struct fsnotify_mark *fsn_mark;
 640         __u32 added;
 641         int ret = 0;
 642
 643         pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
 644
 645         /*
 646          * If some other task has this inode open for write we should not add
 647          * an ignored mark, unless that ignored mark is supposed to survive
 648          * modification changes anyway.
 649          */
 650         if ((flags & FAN_MARK_IGNORED_MASK) &&
 651             !(flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
 652             (atomic_read(&inode->i_writecount) > 0))
 653                 return 0;
 654
 655         fsn_mark = fsnotify_find_inode_mark(group, inode);
 656         if (!fsn_mark) {
 657                 if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
 658                         return -ENOSPC;
 659
 660                 fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
 661                 if (!fsn_mark)
 662                         return -ENOMEM;
 663
 664                 fsnotify_init_mark(fsn_mark, fanotify_free_mark);
 665                 ret = fsnotify_add_mark(fsn_mark, group, inode, NULL, 0);
 666                 if (ret)
 667                         goto err;
 668         }
 669         added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
 670
 671         if (added & ~inode->i_fsnotify_mask)
 672                 fsnotify_recalc_inode_mask(inode);
 673 err:
 674         fsnotify_put_mark(fsn_mark);
 675         return ret;
 676 }
 677
 678 /* fanotify syscalls */
 679 SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 680 {
 681         struct fsnotify_group *group;
 682         int f_flags, fd;
 683         struct user_struct *user;
 684
 685         pr_debug("%s: flags=%d event_f_flags=%d\n",
 686                 __func__, flags, event_f_flags);
 687
 688         if (!capable(CAP_SYS_ADMIN))
 689                 return -EPERM;
 690
 691         if (flags & ~FAN_ALL_INIT_FLAGS)
 692                 return -EINVAL;
 693
 694         user = get_current_user();
 695         if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {
 696                 free_uid(user);
 697                 return -EMFILE;
 698         }
 699
 700         f_flags = O_RDWR | FMODE_NONOTIFY;
 701         if (flags & FAN_CLOEXEC)
 702                 f_flags |= O_CLOEXEC;
 703         if (flags & FAN_NONBLOCK)
 704                 f_flags |= O_NONBLOCK;
 705
 706         /* fsnotify_alloc_group takes a ref.  Dropped in fanotify_release */
 707         group = fsnotify_alloc_group(&fanotify_fsnotify_ops);
 708         if (IS_ERR(group)) {
 709                 free_uid(user);
 710                 return PTR_ERR(group);
 711         }
 712
 713         group->fanotify_data.user = user;
 714         atomic_inc(&user->fanotify_listeners);
 715
 716         group->fanotify_data.f_flags = event_f_flags;
 717 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 718         mutex_init(&group->fanotify_data.access_mutex);
 719         init_waitqueue_head(&group->fanotify_data.access_waitq);
 720         INIT_LIST_HEAD(&group->fanotify_data.access_list);
 721         atomic_set(&group->fanotify_data.bypass_perm, 0);
 722 #endif
 723         switch (flags & FAN_ALL_CLASS_BITS) {
 724         case FAN_CLASS_NOTIF:
 725                 group->priority = FS_PRIO_0;
 726                 break;
 727         case FAN_CLASS_CONTENT:
 728                 group->priority = FS_PRIO_1;
 729                 break;
 730         case FAN_CLASS_PRE_CONTENT:
 731                 group->priority = FS_PRIO_2;
 732                 break;
 733         default:
 734                 fd = -EINVAL;
 735                 goto out_put_group;
 736         }
 737
 738         if (flags & FAN_UNLIMITED_QUEUE) {
 739                 fd = -EPERM;
 740                 if (!capable(CAP_SYS_ADMIN))
 741                         goto out_put_group;
 742                 group->max_events = UINT_MAX;
 743         } else {
 744                 group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS;
 745         }
 746
 747         if (flags & FAN_UNLIMITED_MARKS) {
 748                 fd = -EPERM;
 749                 if (!capable(CAP_SYS_ADMIN))
 750                         goto out_put_group;
 751                 group->fanotify_data.max_marks = UINT_MAX;
 752         } else {
 753                 group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS;
 754         }
 755
 756         fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
 757         if (fd < 0)
 758                 goto out_put_group;
 759
 760         return fd;
 761
 762 out_put_group:
 763         fsnotify_put_group(group);
 764         return fd;
 765 }
 766
 767 SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
 768                               __u64 mask, int dfd,
 769                               const char  __user * pathname)
 770 {
 771         struct inode *inode = NULL;
 772         struct vfsmount *mnt = NULL;
 773         struct fsnotify_group *group;
 774         struct file *filp;
 775         struct path path;
 776         int ret, fput_needed;
 777
 778         pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
 779                  __func__, fanotify_fd, flags, dfd, pathname, mask);
 780
 781         /* we only use the lower 32 bits as of right now. */
 782         if (mask & ((__u64)0xffffffff << 32))
 783                 return -EINVAL;
 784
 785         if (flags & ~FAN_ALL_MARK_FLAGS)
 786                 return -EINVAL;
 787         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
 788         case FAN_MARK_ADD:              /* fallthrough */
 789         case FAN_MARK_REMOVE:
 790                 if (!mask)
 791                         return -EINVAL;
 792         case FAN_MARK_FLUSH:
 793                 break;
 794         default:
 795                 return -EINVAL;
 796         }
 797
 798         if (mask & FAN_ONDIR) {
 799                 flags |= FAN_MARK_ONDIR;
 800                 mask &= ~FAN_ONDIR;
 801         }
 802
 803 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 804         if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD))
 805 #else
 806         if (mask & ~(FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD))
 807 #endif
 808                 return -EINVAL;
 809
 810         filp = fget_light(fanotify_fd, &fput_needed);
 811         if (unlikely(!filp))
 812                 return -EBADF;
 813
 814         /* verify that this is indeed an fanotify instance */
 815         ret = -EINVAL;
 816         if (unlikely(filp->f_op != &fanotify_fops))
 817                 goto fput_and_out;
 818         group = filp->private_data;
 819
 820         /*
 821          * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF.  These are not
 822          * allowed to set permissions events.
 823          */
 824         ret = -EINVAL;
 825         if (mask & FAN_ALL_PERM_EVENTS &&
 826             group->priority == FS_PRIO_0)
 827                 goto fput_and_out;
 828
 829         ret = fanotify_find_path(dfd, pathname, &path, flags);
 830         if (ret)
 831                 goto fput_and_out;
 832
 833         /* inode held in place by reference to path; group by fget on fd */
 834         if (!(flags & FAN_MARK_MOUNT))
 835                 inode = path.dentry->d_inode;
 836         else
 837                 mnt = path.mnt;
 838
 839         /* create/update an inode mark */
 840         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
 841         case FAN_MARK_ADD:
 842                 if (flags & FAN_MARK_MOUNT)
 843                         ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags);
 844                 else
 845                         ret = fanotify_add_inode_mark(group, inode, mask, flags);
 846                 break;
 847         case FAN_MARK_REMOVE:
 848                 if (flags & FAN_MARK_MOUNT)
 849                         ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags);
 850                 else
 851                         ret = fanotify_remove_inode_mark(group, inode, mask, flags);
 852                 break;
 853         case FAN_MARK_FLUSH:
 854                 if (flags & FAN_MARK_MOUNT)
 855                         fsnotify_clear_vfsmount_marks_by_group(group);
 856                 else
 857                         fsnotify_clear_inode_marks_by_group(group);
 858                 break;
 859         default:
 860                 ret = -EINVAL;
 861         }
 862
 863         path_put(&path);
 864 fput_and_out:
 865         fput_light(filp, fput_needed);
 866         return ret;
 867 }
 868
 869 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 870 asmlinkage long SyS_fanotify_mark(long fanotify_fd, long flags, __u64 mask,
 871                                   long dfd, long pathname)
 872 {
 873         return SYSC_fanotify_mark((int) fanotify_fd, (unsigned int) flags,
 874                                   mask, (int) dfd,
 875                                   (const char  __user *) pathname);
 876 }
 877 SYSCALL_ALIAS(sys_fanotify_mark, SyS_fanotify_mark);
 878 #endif
 879
 880 /*
 881  * fanotify_user_setup - Our initialization function.  Note that we cannot return
 882  * error because we have compiled-in VFS hooks.  So an (unlikely) failure here
 883  * must result in panic().
 884  */
 885 static int __init fanotify_user_setup(void)
 886 {
 887         fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC);
 888         fanotify_response_event_cache = KMEM_CACHE(fanotify_response_event,
 889                                                    SLAB_PANIC);
 890
 891         return 0;
 892 }
 893 device_initcall(fanotify_user_setup);