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 #include <linux/compat.h>
  17 #include <linux/sched/signal.h>
  18
  19 #include <asm/ioctls.h>
  20
  21 #include "../../mount.h"
  22 #include "../fdinfo.h"
  23 #include "fanotify.h"
  24
  25 #define FANOTIFY_DEFAULT_MAX_EVENTS     16384
  26 #define FANOTIFY_DEFAULT_MAX_MARKS      8192
  27 #define FANOTIFY_DEFAULT_MAX_LISTENERS  128
  28
  29 /*
  30  * All flags that may be specified in parameter event_f_flags of fanotify_init.
  31  *
  32  * Internal and external open flags are stored together in field f_flags of
  33  * struct file. Only external open flags shall be allowed in event_f_flags.
  34  * Internal flags like FMODE_NONOTIFY, FMODE_EXEC, FMODE_NOCMTIME shall be
  35  * excluded.
  36  */
  37 #define FANOTIFY_INIT_ALL_EVENT_F_BITS                          ( \
  38                 O_ACCMODE       | O_APPEND      | O_NONBLOCK    | \
  39                 __O_SYNC        | O_DSYNC       | O_CLOEXEC     | \
  40                 O_LARGEFILE     | O_NOATIME     )
  41
  42 extern const struct fsnotify_ops fanotify_fsnotify_ops;
  43
  44 static struct kmem_cache *fanotify_mark_cache __read_mostly;
  45 struct kmem_cache *fanotify_event_cachep __read_mostly;
  46 struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
  47
  48 /*
  49  * Get an fsnotify notification event if one exists and is small
  50  * enough to fit in "count". Return an error pointer if the count
  51  * is not large enough.
  52  *
  53  * Called with the group->notification_lock held.
  54  */
  55 static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
  56                                             size_t count)
  57 {
  58         assert_spin_locked(&group->notification_lock);
  59
  60         pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
  61
  62         if (fsnotify_notify_queue_is_empty(group))
  63                 return NULL;
  64
  65         if (FAN_EVENT_METADATA_LEN > count)
  66                 return ERR_PTR(-EINVAL);
  67
  68         /* held the notification_lock the whole time, so this is the
  69          * same event we peeked above */
  70         return fsnotify_remove_first_event(group);
  71 }
  72
  73 static int create_fd(struct fsnotify_group *group,
  74                      struct fanotify_event_info *event,
  75                      struct file **file)
  76 {
  77         int client_fd;
  78         struct file *new_file;
  79
  80         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
  81
  82         client_fd = get_unused_fd_flags(group->fanotify_data.f_flags);
  83         if (client_fd < 0)
  84                 return client_fd;
  85
  86         /*
  87          * we need a new file handle for the userspace program so it can read even if it was
  88          * originally opened O_WRONLY.
  89          */
  90         /* it's possible this event was an overflow event.  in that case dentry and mnt
  91          * are NULL;  That's fine, just don't call dentry open */
  92         if (event->path.dentry && event->path.mnt)
  93                 new_file = dentry_open(&event->path,
  94                                        group->fanotify_data.f_flags | FMODE_NONOTIFY,
  95                                        current_cred());
  96         else
  97                 new_file = ERR_PTR(-EOVERFLOW);
  98         if (IS_ERR(new_file)) {
  99                 /*
 100                  * we still send an event even if we can't open the file.  this
 101                  * can happen when say tasks are gone and we try to open their
 102                  * /proc files or we try to open a WRONLY file like in sysfs
 103                  * we just send the errno to userspace since there isn't much
 104                  * else we can do.
 105                  */
 106                 put_unused_fd(client_fd);
 107                 client_fd = PTR_ERR(new_file);
 108         } else {
 109                 *file = new_file;
 110         }
 111
 112         return client_fd;
 113 }
 114
 115 static int fill_event_metadata(struct fsnotify_group *group,
 116                                struct fanotify_event_metadata *metadata,
 117                                struct fsnotify_event *fsn_event,
 118                                struct file **file)
 119 {
 120         int ret = 0;
 121         struct fanotify_event_info *event;
 122
 123         pr_debug("%s: group=%p metadata=%p event=%p\n", __func__,
 124                  group, metadata, fsn_event);
 125
 126         *file = NULL;
 127         event = container_of(fsn_event, struct fanotify_event_info, fse);
 128         metadata->event_len = FAN_EVENT_METADATA_LEN;
 129         metadata->metadata_len = FAN_EVENT_METADATA_LEN;
 130         metadata->vers = FANOTIFY_METADATA_VERSION;
 131         metadata->reserved = 0;
 132         metadata->mask = fsn_event->mask & FAN_ALL_OUTGOING_EVENTS;
 133         metadata->pid = pid_vnr(event->tgid);
 134         if (unlikely(fsn_event->mask & FAN_Q_OVERFLOW))
 135                 metadata->fd = FAN_NOFD;
 136         else {
 137                 metadata->fd = create_fd(group, event, file);
 138                 if (metadata->fd < 0)
 139                         ret = metadata->fd;
 140         }
 141
 142         return ret;
 143 }
 144
 145 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 146 static struct fanotify_perm_event_info *dequeue_event(
 147                                 struct fsnotify_group *group, int fd)
 148 {
 149         struct fanotify_perm_event_info *event, *return_e = NULL;
 150
 151         spin_lock(&group->notification_lock);
 152         list_for_each_entry(event, &group->fanotify_data.access_list,
 153                             fae.fse.list) {
 154                 if (event->fd != fd)
 155                         continue;
 156
 157                 list_del_init(&event->fae.fse.list);
 158                 return_e = event;
 159                 break;
 160         }
 161         spin_unlock(&group->notification_lock);
 162
 163         pr_debug("%s: found return_re=%p\n", __func__, return_e);
 164
 165         return return_e;
 166 }
 167
 168 static int process_access_response(struct fsnotify_group *group,
 169                                    struct fanotify_response *response_struct)
 170 {
 171         struct fanotify_perm_event_info *event;
 172         int fd = response_struct->fd;
 173         int response = response_struct->response;
 174
 175         pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group,
 176                  fd, response);
 177         /*
 178          * make sure the response is valid, if invalid we do nothing and either
 179          * userspace can send a valid response or we will clean it up after the
 180          * timeout
 181          */
 182         switch (response) {
 183         case FAN_ALLOW:
 184         case FAN_DENY:
 185                 break;
 186         default:
 187                 return -EINVAL;
 188         }
 189
 190         if (fd < 0)
 191                 return -EINVAL;
 192
 193         event = dequeue_event(group, fd);
 194         if (!event)
 195                 return -ENOENT;
 196
 197         event->response = response;
 198         wake_up(&group->fanotify_data.access_waitq);
 199
 200         return 0;
 201 }
 202 #endif
 203
 204 static ssize_t copy_event_to_user(struct fsnotify_group *group,
 205                                   struct fsnotify_event *event,
 206                                   char __user *buf)
 207 {
 208         struct fanotify_event_metadata fanotify_event_metadata;
 209         struct file *f;
 210         int fd, ret;
 211
 212         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
 213
 214         ret = fill_event_metadata(group, &fanotify_event_metadata, event, &f);
 215         if (ret < 0)
 216                 return ret;
 217
 218         fd = fanotify_event_metadata.fd;
 219         ret = -EFAULT;
 220         if (copy_to_user(buf, &fanotify_event_metadata,
 221                          fanotify_event_metadata.event_len))
 222                 goto out_close_fd;
 223
 224 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 225         if (event->mask & FAN_ALL_PERM_EVENTS)
 226                 FANOTIFY_PE(event)->fd = fd;
 227 #endif
 228
 229         if (fd != FAN_NOFD)
 230                 fd_install(fd, f);
 231         return fanotify_event_metadata.event_len;
 232
 233 out_close_fd:
 234         if (fd != FAN_NOFD) {
 235                 put_unused_fd(fd);
 236                 fput(f);
 237         }
 238         return ret;
 239 }
 240
 241 /* intofiy userspace file descriptor functions */
 242 static unsigned int fanotify_poll(struct file *file, poll_table *wait)
 243 {
 244         struct fsnotify_group *group = file->private_data;
 245         int ret = 0;
 246
 247         poll_wait(file, &group->notification_waitq, wait);
 248         spin_lock(&group->notification_lock);
 249         if (!fsnotify_notify_queue_is_empty(group))
 250                 ret = POLLIN | POLLRDNORM;
 251         spin_unlock(&group->notification_lock);
 252
 253         return ret;
 254 }
 255
 256 static ssize_t fanotify_read(struct file *file, char __user *buf,
 257                              size_t count, loff_t *pos)
 258 {
 259         struct fsnotify_group *group;
 260         struct fsnotify_event *kevent;
 261         char __user *start;
 262         int ret;
 263         DEFINE_WAIT_FUNC(wait, woken_wake_function);
 264
 265         start = buf;
 266         group = file->private_data;
 267
 268         pr_debug("%s: group=%p\n", __func__, group);
 269
 270         add_wait_queue(&group->notification_waitq, &wait);
 271         while (1) {
 272                 spin_lock(&group->notification_lock);
 273                 kevent = get_one_event(group, count);
 274                 spin_unlock(&group->notification_lock);
 275
 276                 if (IS_ERR(kevent)) {
 277                         ret = PTR_ERR(kevent);
 278                         break;
 279                 }
 280
 281                 if (!kevent) {
 282                         ret = -EAGAIN;
 283                         if (file->f_flags & O_NONBLOCK)
 284                                 break;
 285
 286                         ret = -ERESTARTSYS;
 287                         if (signal_pending(current))
 288                                 break;
 289
 290                         if (start != buf)
 291                                 break;
 292
 293                         wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
 294                         continue;
 295                 }
 296
 297                 ret = copy_event_to_user(group, kevent, buf);
 298                 /*
 299                  * Permission events get queued to wait for response.  Other
 300                  * events can be destroyed now.
 301                  */
 302                 if (!(kevent->mask & FAN_ALL_PERM_EVENTS)) {
 303                         fsnotify_destroy_event(group, kevent);
 304                         if (ret < 0)
 305                                 break;
 306                 } else {
 307 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 308                         if (ret < 0) {
 309                                 FANOTIFY_PE(kevent)->response = FAN_DENY;
 310                                 wake_up(&group->fanotify_data.access_waitq);
 311                                 break;
 312                         }
 313                         spin_lock(&group->notification_lock);
 314                         list_add_tail(&kevent->list,
 315                                       &group->fanotify_data.access_list);
 316                         spin_unlock(&group->notification_lock);
 317 #endif
 318                 }
 319                 buf += ret;
 320                 count -= ret;
 321         }
 322         remove_wait_queue(&group->notification_waitq, &wait);
 323
 324         if (start != buf && ret != -EFAULT)
 325                 ret = buf - start;
 326         return ret;
 327 }
 328
 329 static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
 330 {
 331 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 332         struct fanotify_response response = { .fd = -1, .response = -1 };
 333         struct fsnotify_group *group;
 334         int ret;
 335
 336         group = file->private_data;
 337
 338         if (count > sizeof(response))
 339                 count = sizeof(response);
 340
 341         pr_debug("%s: group=%p count=%zu\n", __func__, group, count);
 342
 343         if (copy_from_user(&response, buf, count))
 344                 return -EFAULT;
 345
 346         ret = process_access_response(group, &response);
 347         if (ret < 0)
 348                 count = ret;
 349
 350         return count;
 351 #else
 352         return -EINVAL;
 353 #endif
 354 }
 355
 356 static int fanotify_release(struct inode *ignored, struct file *file)
 357 {
 358         struct fsnotify_group *group = file->private_data;
 359
 360 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 361         struct fanotify_perm_event_info *event, *next;
 362         struct fsnotify_event *fsn_event;
 363
 364         /*
 365          * Stop new events from arriving in the notification queue. since
 366          * userspace cannot use fanotify fd anymore, no event can enter or
 367          * leave access_list by now either.
 368          */
 369         fsnotify_group_stop_queueing(group);
 370
 371         /*
 372          * Process all permission events on access_list and notification queue
 373          * and simulate reply from userspace.
 374          */
 375         spin_lock(&group->notification_lock);
 376         list_for_each_entry_safe(event, next, &group->fanotify_data.access_list,
 377                                  fae.fse.list) {
 378                 pr_debug("%s: found group=%p event=%p\n", __func__, group,
 379                          event);
 380
 381                 list_del_init(&event->fae.fse.list);
 382                 event->response = FAN_ALLOW;
 383         }
 384
 385         /*
 386          * Destroy all non-permission events. For permission events just
 387          * dequeue them and set the response. They will be freed once the
 388          * response is consumed and fanotify_get_response() returns.
 389          */
 390         while (!fsnotify_notify_queue_is_empty(group)) {
 391                 fsn_event = fsnotify_remove_first_event(group);
 392                 if (!(fsn_event->mask & FAN_ALL_PERM_EVENTS)) {
 393                         spin_unlock(&group->notification_lock);
 394                         fsnotify_destroy_event(group, fsn_event);
 395                         spin_lock(&group->notification_lock);
 396                 } else
 397                         FANOTIFY_PE(fsn_event)->response = FAN_ALLOW;
 398         }
 399         spin_unlock(&group->notification_lock);
 400
 401         /* Response for all permission events it set, wakeup waiters */
 402         wake_up(&group->fanotify_data.access_waitq);
 403 #endif
 404
 405         /* matches the fanotify_init->fsnotify_alloc_group */
 406         fsnotify_destroy_group(group);
 407
 408         return 0;
 409 }
 410
 411 static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 412 {
 413         struct fsnotify_group *group;
 414         struct fsnotify_event *fsn_event;
 415         void __user *p;
 416         int ret = -ENOTTY;
 417         size_t send_len = 0;
 418
 419         group = file->private_data;
 420
 421         p = (void __user *) arg;
 422
 423         switch (cmd) {
 424         case FIONREAD:
 425                 spin_lock(&group->notification_lock);
 426                 list_for_each_entry(fsn_event, &group->notification_list, list)
 427                         send_len += FAN_EVENT_METADATA_LEN;
 428                 spin_unlock(&group->notification_lock);
 429                 ret = put_user(send_len, (int __user *) p);
 430                 break;
 431         }
 432
 433         return ret;
 434 }
 435
 436 static const struct file_operations fanotify_fops = {
 437         .show_fdinfo    = fanotify_show_fdinfo,
 438         .poll           = fanotify_poll,
 439         .read           = fanotify_read,
 440         .write          = fanotify_write,
 441         .fasync         = NULL,
 442         .release        = fanotify_release,
 443         .unlocked_ioctl = fanotify_ioctl,
 444         .compat_ioctl   = fanotify_ioctl,
 445         .llseek         = noop_llseek,
 446 };
 447
 448 static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
 449 {
 450         kmem_cache_free(fanotify_mark_cache, fsn_mark);
 451 }
 452
 453 static int fanotify_find_path(int dfd, const char __user *filename,
 454                               struct path *path, unsigned int flags)
 455 {
 456         int ret;
 457
 458         pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__,
 459                  dfd, filename, flags);
 460
 461         if (filename == NULL) {
 462                 struct fd f = fdget(dfd);
 463
 464                 ret = -EBADF;
 465                 if (!f.file)
 466                         goto out;
 467
 468                 ret = -ENOTDIR;
 469                 if ((flags & FAN_MARK_ONLYDIR) &&
 470                     !(S_ISDIR(file_inode(f.file)->i_mode))) {
 471                         fdput(f);
 472                         goto out;
 473                 }
 474
 475                 *path = f.file->f_path;
 476                 path_get(path);
 477                 fdput(f);
 478         } else {
 479                 unsigned int lookup_flags = 0;
 480
 481                 if (!(flags & FAN_MARK_DONT_FOLLOW))
 482                         lookup_flags |= LOOKUP_FOLLOW;
 483                 if (flags & FAN_MARK_ONLYDIR)
 484                         lookup_flags |= LOOKUP_DIRECTORY;
 485
 486                 ret = user_path_at(dfd, filename, lookup_flags, path);
 487                 if (ret)
 488                         goto out;
 489         }
 490
 491         /* you can only watch an inode if you have read permissions on it */
 492         ret = inode_permission(path->dentry->d_inode, MAY_READ);
 493         if (ret)
 494                 path_put(path);
 495 out:
 496         return ret;
 497 }
 498
 499 static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
 500                                             __u32 mask,
 501                                             unsigned int flags,
 502                                             int *destroy)
 503 {
 504         __u32 oldmask = 0;
 505
 506         spin_lock(&fsn_mark->lock);
 507         if (!(flags & FAN_MARK_IGNORED_MASK)) {
 508                 __u32 tmask = fsn_mark->mask & ~mask;
 509
 510                 if (flags & FAN_MARK_ONDIR)
 511                         tmask &= ~FAN_ONDIR;
 512
 513                 oldmask = fsn_mark->mask;
 514                 fsnotify_set_mark_mask_locked(fsn_mark, tmask);
 515         } else {
 516                 __u32 tmask = fsn_mark->ignored_mask & ~mask;
 517                 if (flags & FAN_MARK_ONDIR)
 518                         tmask &= ~FAN_ONDIR;
 519
 520                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
 521         }
 522         *destroy = !(fsn_mark->mask | fsn_mark->ignored_mask);
 523         spin_unlock(&fsn_mark->lock);
 524
 525         return mask & oldmask;
 526 }
 527
 528 static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
 529                                          struct vfsmount *mnt, __u32 mask,
 530                                          unsigned int flags)
 531 {
 532         struct fsnotify_mark *fsn_mark = NULL;
 533         __u32 removed;
 534         int destroy_mark;
 535
 536         mutex_lock(&group->mark_mutex);
 537         fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
 538         if (!fsn_mark) {
 539                 mutex_unlock(&group->mark_mutex);
 540                 return -ENOENT;
 541         }
 542
 543         removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags,
 544                                                  &destroy_mark);
 545         if (destroy_mark)
 546                 fsnotify_detach_mark(fsn_mark);
 547         mutex_unlock(&group->mark_mutex);
 548         if (destroy_mark)
 549                 fsnotify_free_mark(fsn_mark);
 550
 551         fsnotify_put_mark(fsn_mark);
 552         if (removed & real_mount(mnt)->mnt_fsnotify_mask)
 553                 fsnotify_recalc_vfsmount_mask(mnt);
 554
 555         return 0;
 556 }
 557
 558 static int fanotify_remove_inode_mark(struct fsnotify_group *group,
 559                                       struct inode *inode, __u32 mask,
 560                                       unsigned int flags)
 561 {
 562         struct fsnotify_mark *fsn_mark = NULL;
 563         __u32 removed;
 564         int destroy_mark;
 565
 566         mutex_lock(&group->mark_mutex);
 567         fsn_mark = fsnotify_find_inode_mark(group, inode);
 568         if (!fsn_mark) {
 569                 mutex_unlock(&group->mark_mutex);
 570                 return -ENOENT;
 571         }
 572
 573         removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags,
 574                                                  &destroy_mark);
 575         if (destroy_mark)
 576                 fsnotify_detach_mark(fsn_mark);
 577         mutex_unlock(&group->mark_mutex);
 578         if (destroy_mark)
 579                 fsnotify_free_mark(fsn_mark);
 580
 581         /* matches the fsnotify_find_inode_mark() */
 582         fsnotify_put_mark(fsn_mark);
 583         if (removed & inode->i_fsnotify_mask)
 584                 fsnotify_recalc_inode_mask(inode);
 585
 586         return 0;
 587 }
 588
 589 static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
 590                                        __u32 mask,
 591                                        unsigned int flags)
 592 {
 593         __u32 oldmask = -1;
 594
 595         spin_lock(&fsn_mark->lock);
 596         if (!(flags & FAN_MARK_IGNORED_MASK)) {
 597                 __u32 tmask = fsn_mark->mask | mask;
 598
 599                 if (flags & FAN_MARK_ONDIR)
 600                         tmask |= FAN_ONDIR;
 601
 602                 oldmask = fsn_mark->mask;
 603                 fsnotify_set_mark_mask_locked(fsn_mark, tmask);
 604         } else {
 605                 __u32 tmask = fsn_mark->ignored_mask | mask;
 606                 if (flags & FAN_MARK_ONDIR)
 607                         tmask |= FAN_ONDIR;
 608
 609                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
 610                 if (flags & FAN_MARK_IGNORED_SURV_MODIFY)
 611                         fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
 612         }
 613         spin_unlock(&fsn_mark->lock);
 614
 615         return mask & ~oldmask;
 616 }
 617
 618 static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
 619                                                    struct inode *inode,
 620                                                    struct vfsmount *mnt)
 621 {
 622         struct fsnotify_mark *mark;
 623         int ret;
 624
 625         if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
 626                 return ERR_PTR(-ENOSPC);
 627
 628         mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
 629         if (!mark)
 630                 return ERR_PTR(-ENOMEM);
 631
 632         fsnotify_init_mark(mark, fanotify_free_mark);
 633         ret = fsnotify_add_mark_locked(mark, group, inode, mnt, 0);
 634         if (ret) {
 635                 fsnotify_put_mark(mark);
 636                 return ERR_PTR(ret);
 637         }
 638
 639         return mark;
 640 }
 641
 642
 643 static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
 644                                       struct vfsmount *mnt, __u32 mask,
 645                                       unsigned int flags)
 646 {
 647         struct fsnotify_mark *fsn_mark;
 648         __u32 added;
 649
 650         mutex_lock(&group->mark_mutex);
 651         fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
 652         if (!fsn_mark) {
 653                 fsn_mark = fanotify_add_new_mark(group, NULL, mnt);
 654                 if (IS_ERR(fsn_mark)) {
 655                         mutex_unlock(&group->mark_mutex);
 656                         return PTR_ERR(fsn_mark);
 657                 }
 658         }
 659         added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
 660         mutex_unlock(&group->mark_mutex);
 661
 662         if (added & ~real_mount(mnt)->mnt_fsnotify_mask)
 663                 fsnotify_recalc_vfsmount_mask(mnt);
 664
 665         fsnotify_put_mark(fsn_mark);
 666         return 0;
 667 }
 668
 669 static int fanotify_add_inode_mark(struct fsnotify_group *group,
 670                                    struct inode *inode, __u32 mask,
 671                                    unsigned int flags)
 672 {
 673         struct fsnotify_mark *fsn_mark;
 674         __u32 added;
 675
 676         pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
 677
 678         /*
 679          * If some other task has this inode open for write we should not add
 680          * an ignored mark, unless that ignored mark is supposed to survive
 681          * modification changes anyway.
 682          */
 683         if ((flags & FAN_MARK_IGNORED_MASK) &&
 684             !(flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
 685             (atomic_read(&inode->i_writecount) > 0))
 686                 return 0;
 687
 688         mutex_lock(&group->mark_mutex);
 689         fsn_mark = fsnotify_find_inode_mark(group, inode);
 690         if (!fsn_mark) {
 691                 fsn_mark = fanotify_add_new_mark(group, inode, NULL);
 692                 if (IS_ERR(fsn_mark)) {
 693                         mutex_unlock(&group->mark_mutex);
 694                         return PTR_ERR(fsn_mark);
 695                 }
 696         }
 697         added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
 698         mutex_unlock(&group->mark_mutex);
 699
 700         if (added & ~inode->i_fsnotify_mask)
 701                 fsnotify_recalc_inode_mask(inode);
 702
 703         fsnotify_put_mark(fsn_mark);
 704         return 0;
 705 }
 706
 707 /* fanotify syscalls */
 708 SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 709 {
 710         struct fsnotify_group *group;
 711         int f_flags, fd;
 712         struct user_struct *user;
 713         struct fanotify_event_info *oevent;
 714
 715         pr_debug("%s: flags=%d event_f_flags=%d\n",
 716                 __func__, flags, event_f_flags);
 717
 718         if (!capable(CAP_SYS_ADMIN))
 719                 return -EPERM;
 720
 721         if (flags & ~FAN_ALL_INIT_FLAGS)
 722                 return -EINVAL;
 723
 724         if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS)
 725                 return -EINVAL;
 726
 727         switch (event_f_flags & O_ACCMODE) {
 728         case O_RDONLY:
 729         case O_RDWR:
 730         case O_WRONLY:
 731                 break;
 732         default:
 733                 return -EINVAL;
 734         }
 735
 736         user = get_current_user();
 737         if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {
 738                 free_uid(user);
 739                 return -EMFILE;
 740         }
 741
 742         f_flags = O_RDWR | FMODE_NONOTIFY;
 743         if (flags & FAN_CLOEXEC)
 744                 f_flags |= O_CLOEXEC;
 745         if (flags & FAN_NONBLOCK)
 746                 f_flags |= O_NONBLOCK;
 747
 748         /* fsnotify_alloc_group takes a ref.  Dropped in fanotify_release */
 749         group = fsnotify_alloc_group(&fanotify_fsnotify_ops);
 750         if (IS_ERR(group)) {
 751                 free_uid(user);
 752                 return PTR_ERR(group);
 753         }
 754
 755         group->fanotify_data.user = user;
 756         atomic_inc(&user->fanotify_listeners);
 757
 758         oevent = fanotify_alloc_event(NULL, FS_Q_OVERFLOW, NULL);
 759         if (unlikely(!oevent)) {
 760                 fd = -ENOMEM;
 761                 goto out_destroy_group;
 762         }
 763         group->overflow_event = &oevent->fse;
 764
 765         if (force_o_largefile())
 766                 event_f_flags |= O_LARGEFILE;
 767         group->fanotify_data.f_flags = event_f_flags;
 768 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 769         init_waitqueue_head(&group->fanotify_data.access_waitq);
 770         INIT_LIST_HEAD(&group->fanotify_data.access_list);
 771 #endif
 772         switch (flags & FAN_ALL_CLASS_BITS) {
 773         case FAN_CLASS_NOTIF:
 774                 group->priority = FS_PRIO_0;
 775                 break;
 776         case FAN_CLASS_CONTENT:
 777                 group->priority = FS_PRIO_1;
 778                 break;
 779         case FAN_CLASS_PRE_CONTENT:
 780                 group->priority = FS_PRIO_2;
 781                 break;
 782         default:
 783                 fd = -EINVAL;
 784                 goto out_destroy_group;
 785         }
 786
 787         if (flags & FAN_UNLIMITED_QUEUE) {
 788                 fd = -EPERM;
 789                 if (!capable(CAP_SYS_ADMIN))
 790                         goto out_destroy_group;
 791                 group->max_events = UINT_MAX;
 792         } else {
 793                 group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS;
 794         }
 795
 796         if (flags & FAN_UNLIMITED_MARKS) {
 797                 fd = -EPERM;
 798                 if (!capable(CAP_SYS_ADMIN))
 799                         goto out_destroy_group;
 800                 group->fanotify_data.max_marks = UINT_MAX;
 801         } else {
 802                 group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS;
 803         }
 804
 805         fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
 806         if (fd < 0)
 807                 goto out_destroy_group;
 808
 809         return fd;
 810
 811 out_destroy_group:
 812         fsnotify_destroy_group(group);
 813         return fd;
 814 }
 815
 816 SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags,
 817                               __u64, mask, int, dfd,
 818                               const char  __user *, pathname)
 819 {
 820         struct inode *inode = NULL;
 821         struct vfsmount *mnt = NULL;
 822         struct fsnotify_group *group;
 823         struct fd f;
 824         struct path path;
 825         int ret;
 826
 827         pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
 828                  __func__, fanotify_fd, flags, dfd, pathname, mask);
 829
 830         /* we only use the lower 32 bits as of right now. */
 831         if (mask & ((__u64)0xffffffff << 32))
 832                 return -EINVAL;
 833
 834         if (flags & ~FAN_ALL_MARK_FLAGS)
 835                 return -EINVAL;
 836         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
 837         case FAN_MARK_ADD:              /* fallthrough */
 838         case FAN_MARK_REMOVE:
 839                 if (!mask)
 840                         return -EINVAL;
 841                 break;
 842         case FAN_MARK_FLUSH:
 843                 if (flags & ~(FAN_MARK_MOUNT | FAN_MARK_FLUSH))
 844                         return -EINVAL;
 845                 break;
 846         default:
 847                 return -EINVAL;
 848         }
 849
 850         if (mask & FAN_ONDIR) {
 851                 flags |= FAN_MARK_ONDIR;
 852                 mask &= ~FAN_ONDIR;
 853         }
 854
 855 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 856         if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD))
 857 #else
 858         if (mask & ~(FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD))
 859 #endif
 860                 return -EINVAL;
 861
 862         f = fdget(fanotify_fd);
 863         if (unlikely(!f.file))
 864                 return -EBADF;
 865
 866         /* verify that this is indeed an fanotify instance */
 867         ret = -EINVAL;
 868         if (unlikely(f.file->f_op != &fanotify_fops))
 869                 goto fput_and_out;
 870         group = f.file->private_data;
 871
 872         /*
 873          * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF.  These are not
 874          * allowed to set permissions events.
 875          */
 876         ret = -EINVAL;
 877         if (mask & FAN_ALL_PERM_EVENTS &&
 878             group->priority == FS_PRIO_0)
 879                 goto fput_and_out;
 880
 881         if (flags & FAN_MARK_FLUSH) {
 882                 ret = 0;
 883                 if (flags & FAN_MARK_MOUNT)
 884                         fsnotify_clear_vfsmount_marks_by_group(group);
 885                 else
 886                         fsnotify_clear_inode_marks_by_group(group);
 887                 goto fput_and_out;
 888         }
 889
 890         ret = fanotify_find_path(dfd, pathname, &path, flags);
 891         if (ret)
 892                 goto fput_and_out;
 893
 894         /* inode held in place by reference to path; group by fget on fd */
 895         if (!(flags & FAN_MARK_MOUNT))
 896                 inode = path.dentry->d_inode;
 897         else
 898                 mnt = path.mnt;
 899
 900         /* create/update an inode mark */
 901         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) {
 902         case FAN_MARK_ADD:
 903                 if (flags & FAN_MARK_MOUNT)
 904                         ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags);
 905                 else
 906                         ret = fanotify_add_inode_mark(group, inode, mask, flags);
 907                 break;
 908         case FAN_MARK_REMOVE:
 909                 if (flags & FAN_MARK_MOUNT)
 910                         ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags);
 911                 else
 912                         ret = fanotify_remove_inode_mark(group, inode, mask, flags);
 913                 break;
 914         default:
 915                 ret = -EINVAL;
 916         }
 917
 918         path_put(&path);
 919 fput_and_out:
 920         fdput(f);
 921         return ret;
 922 }
 923
 924 #ifdef CONFIG_COMPAT
 925 COMPAT_SYSCALL_DEFINE6(fanotify_mark,
 926                                 int, fanotify_fd, unsigned int, flags,
 927                                 __u32, mask0, __u32, mask1, int, dfd,
 928                                 const char  __user *, pathname)
 929 {
 930         return sys_fanotify_mark(fanotify_fd, flags,
 931 #ifdef __BIG_ENDIAN
 932                                 ((__u64)mask0 << 32) | mask1,
 933 #else
 934                                 ((__u64)mask1 << 32) | mask0,
 935 #endif
 936                                  dfd, pathname);
 937 }
 938 #endif
 939
 940 /*
 941  * fanotify_user_setup - Our initialization function.  Note that we cannot return
 942  * error because we have compiled-in VFS hooks.  So an (unlikely) failure here
 943  * must result in panic().
 944  */
 945 static int __init fanotify_user_setup(void)
 946 {
 947         fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC);
 948         fanotify_event_cachep = KMEM_CACHE(fanotify_event_info, SLAB_PANIC);
 949 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 950         fanotify_perm_event_cachep = KMEM_CACHE(fanotify_perm_event_info,
 951                                                 SLAB_PANIC);
 952 #endif
 953
 954         return 0;
 955 }
 956 device_initcall(fanotify_user_setup);