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TOMOYO Linux Cross Reference
Linux/fs/notify/fanotify/fanotify_user.c

Version: ~ [ linux-5.8-rc4 ] ~ [ linux-5.7.7 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.50 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.131 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.187 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.229 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.229 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.85 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  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 
 18 #include <asm/ioctls.h>
 19 
 20 #include "../../mount.h"
 21 #include "../fdinfo.h"
 22 #include "fanotify.h"
 23 
 24 #define FANOTIFY_DEFAULT_MAX_EVENTS     16384
 25 #define FANOTIFY_DEFAULT_MAX_MARKS      8192
 26 #define FANOTIFY_DEFAULT_MAX_LISTENERS  128
 27 
 28 /*
 29  * All flags that may be specified in parameter event_f_flags of fanotify_init.
 30  *
 31  * Internal and external open flags are stored together in field f_flags of
 32  * struct file. Only external open flags shall be allowed in event_f_flags.
 33  * Internal flags like FMODE_NONOTIFY, FMODE_EXEC, FMODE_NOCMTIME shall be
 34  * excluded.
 35  */
 36 #define FANOTIFY_INIT_ALL_EVENT_F_BITS                          ( \
 37                 O_ACCMODE       | O_APPEND      | O_NONBLOCK    | \
 38                 __O_SYNC        | O_DSYNC       | O_CLOEXEC     | \
 39                 O_LARGEFILE     | O_NOATIME     )
 40 
 41 extern const struct fsnotify_ops fanotify_fsnotify_ops;
 42 
 43 static struct kmem_cache *fanotify_mark_cache __read_mostly;
 44 struct kmem_cache *fanotify_event_cachep __read_mostly;
 45 struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
 46 
 47 /*
 48  * Get an fsnotify notification event if one exists and is small
 49  * enough to fit in "count". Return an error pointer if the count
 50  * is not large enough.
 51  *
 52  * Called with the group->notification_mutex held.
 53  */
 54 static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
 55                                             size_t count)
 56 {
 57         BUG_ON(!mutex_is_locked(&group->notification_mutex));
 58 
 59         pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
 60 
 61         if (fsnotify_notify_queue_is_empty(group))
 62                 return NULL;
 63 
 64         if (FAN_EVENT_METADATA_LEN > count)
 65                 return ERR_PTR(-EINVAL);
 66 
 67         /* held the notification_mutex the whole time, so this is the
 68          * same event we peeked above */
 69         return fsnotify_remove_first_event(group);
 70 }
 71 
 72 static int create_fd(struct fsnotify_group *group,
 73                      struct fanotify_event_info *event,
 74                      struct file **file)
 75 {
 76         int client_fd;
 77         struct file *new_file;
 78 
 79         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
 80 
 81         client_fd = get_unused_fd_flags(group->fanotify_data.f_flags);
 82         if (client_fd < 0)
 83                 return client_fd;
 84 
 85         /*
 86          * we need a new file handle for the userspace program so it can read even if it was
 87          * originally opened O_WRONLY.
 88          */
 89         /* it's possible this event was an overflow event.  in that case dentry and mnt
 90          * are NULL;  That's fine, just don't call dentry open */
 91         if (event->path.dentry && event->path.mnt)
 92                 new_file = dentry_open(&event->path,
 93                                        group->fanotify_data.f_flags | FMODE_NONOTIFY,
 94                                        current_cred());
 95         else
 96                 new_file = ERR_PTR(-EOVERFLOW);
 97         if (IS_ERR(new_file)) {
 98                 /*
 99                  * we still send an event even if we can't open the file.  this
100                  * can happen when say tasks are gone and we try to open their
101                  * /proc files or we try to open a WRONLY file like in sysfs
102                  * we just send the errno to userspace since there isn't much
103                  * else we can do.
104                  */
105                 put_unused_fd(client_fd);
106                 client_fd = PTR_ERR(new_file);
107         } else {
108                 *file = new_file;
109         }
110 
111         return client_fd;
112 }
113 
114 static int fill_event_metadata(struct fsnotify_group *group,
115                                struct fanotify_event_metadata *metadata,
116                                struct fsnotify_event *fsn_event,
117                                struct file **file)
118 {
119         int ret = 0;
120         struct fanotify_event_info *event;
121 
122         pr_debug("%s: group=%p metadata=%p event=%p\n", __func__,
123                  group, metadata, fsn_event);
124 
125         *file = NULL;
126         event = container_of(fsn_event, struct fanotify_event_info, fse);
127         metadata->event_len = FAN_EVENT_METADATA_LEN;
128         metadata->metadata_len = FAN_EVENT_METADATA_LEN;
129         metadata->vers = FANOTIFY_METADATA_VERSION;
130         metadata->reserved = 0;
131         metadata->mask = fsn_event->mask & FAN_ALL_OUTGOING_EVENTS;
132         metadata->pid = pid_vnr(event->tgid);
133         if (unlikely(fsn_event->mask & FAN_Q_OVERFLOW))
134                 metadata->fd = FAN_NOFD;
135         else {
136                 metadata->fd = create_fd(group, event, file);
137                 if (metadata->fd < 0)
138                         ret = metadata->fd;
139         }
140 
141         return ret;
142 }
143 
144 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
145 static struct fanotify_perm_event_info *dequeue_event(
146                                 struct fsnotify_group *group, int fd)
147 {
148         struct fanotify_perm_event_info *event, *return_e = NULL;
149 
150         spin_lock(&group->fanotify_data.access_lock);
151         list_for_each_entry(event, &group->fanotify_data.access_list,
152                             fae.fse.list) {
153                 if (event->fd != fd)
154                         continue;
155 
156                 list_del_init(&event->fae.fse.list);
157                 return_e = event;
158                 break;
159         }
160         spin_unlock(&group->fanotify_data.access_lock);
161 
162         pr_debug("%s: found return_re=%p\n", __func__, return_e);
163 
164         return return_e;
165 }
166 
167 static int process_access_response(struct fsnotify_group *group,
168                                    struct fanotify_response *response_struct)
169 {
170         struct fanotify_perm_event_info *event;
171         int fd = response_struct->fd;
172         int response = response_struct->response;
173 
174         pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group,
175                  fd, response);
176         /*
177          * make sure the response is valid, if invalid we do nothing and either
178          * userspace can send a valid response or we will clean it up after the
179          * timeout
180          */
181         switch (response) {
182         case FAN_ALLOW:
183         case FAN_DENY:
184                 break;
185         default:
186                 return -EINVAL;
187         }
188 
189         if (fd < 0)
190                 return -EINVAL;
191 
192         event = dequeue_event(group, fd);
193         if (!event)
194                 return -ENOENT;
195 
196         event->response = response;
197         wake_up(&group->fanotify_data.access_waitq);
198 
199         return 0;
200 }
201 #endif
202 
203 static ssize_t copy_event_to_user(struct fsnotify_group *group,
204                                   struct fsnotify_event *event,
205                                   char __user *buf)
206 {
207         struct fanotify_event_metadata fanotify_event_metadata;
208         struct file *f;
209         int fd, ret;
210 
211         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
212 
213         ret = fill_event_metadata(group, &fanotify_event_metadata, event, &f);
214         if (ret < 0)
215                 return ret;
216 
217         fd = fanotify_event_metadata.fd;
218         ret = -EFAULT;
219         if (copy_to_user(buf, &fanotify_event_metadata,
220                          fanotify_event_metadata.event_len))
221                 goto out_close_fd;
222 
223 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
224         if (event->mask & FAN_ALL_PERM_EVENTS)
225                 FANOTIFY_PE(event)->fd = fd;
226 #endif
227 
228         if (fd != FAN_NOFD)
229                 fd_install(fd, f);
230         return fanotify_event_metadata.event_len;
231 
232 out_close_fd:
233         if (fd != FAN_NOFD) {
234                 put_unused_fd(fd);
235                 fput(f);
236         }
237         return ret;
238 }
239 
240 /* intofiy userspace file descriptor functions */
241 static unsigned int fanotify_poll(struct file *file, poll_table *wait)
242 {
243         struct fsnotify_group *group = file->private_data;
244         int ret = 0;
245 
246         poll_wait(file, &group->notification_waitq, wait);
247         mutex_lock(&group->notification_mutex);
248         if (!fsnotify_notify_queue_is_empty(group))
249                 ret = POLLIN | POLLRDNORM;
250         mutex_unlock(&group->notification_mutex);
251 
252         return ret;
253 }
254 
255 static ssize_t fanotify_read(struct file *file, char __user *buf,
256                              size_t count, loff_t *pos)
257 {
258         struct fsnotify_group *group;
259         struct fsnotify_event *kevent;
260         char __user *start;
261         int ret;
262         DEFINE_WAIT_FUNC(wait, woken_wake_function);
263 
264         start = buf;
265         group = file->private_data;
266 
267         pr_debug("%s: group=%p\n", __func__, group);
268 
269         add_wait_queue(&group->notification_waitq, &wait);
270         while (1) {
271                 mutex_lock(&group->notification_mutex);
272                 kevent = get_one_event(group, count);
273                 mutex_unlock(&group->notification_mutex);
274 
275                 if (IS_ERR(kevent)) {
276                         ret = PTR_ERR(kevent);
277                         break;
278                 }
279 
280                 if (!kevent) {
281                         ret = -EAGAIN;
282                         if (file->f_flags & O_NONBLOCK)
283                                 break;
284 
285                         ret = -ERESTARTSYS;
286                         if (signal_pending(current))
287                                 break;
288 
289                         if (start != buf)
290                                 break;
291 
292                         wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
293                         continue;
294                 }
295 
296                 ret = copy_event_to_user(group, kevent, buf);
297                 /*
298                  * Permission events get queued to wait for response.  Other
299                  * events can be destroyed now.
300                  */
301                 if (!(kevent->mask & FAN_ALL_PERM_EVENTS)) {
302                         fsnotify_destroy_event(group, kevent);
303                         if (ret < 0)
304                                 break;
305                 } else {
306 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
307                         if (ret < 0) {
308                                 FANOTIFY_PE(kevent)->response = FAN_DENY;
309                                 wake_up(&group->fanotify_data.access_waitq);
310                                 break;
311                         }
312                         spin_lock(&group->fanotify_data.access_lock);
313                         list_add_tail(&kevent->list,
314                                       &group->fanotify_data.access_list);
315                         spin_unlock(&group->fanotify_data.access_lock);
316 #endif
317                 }
318                 buf += ret;
319                 count -= ret;
320         }
321         remove_wait_queue(&group->notification_waitq, &wait);
322 
323         if (start != buf && ret != -EFAULT)
324                 ret = buf - start;
325         return ret;
326 }
327 
328 static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
329 {
330 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
331         struct fanotify_response response = { .fd = -1, .response = -1 };
332         struct fsnotify_group *group;
333         int ret;
334 
335         group = file->private_data;
336 
337         if (count > sizeof(response))
338                 count = sizeof(response);
339 
340         pr_debug("%s: group=%p count=%zu\n", __func__, group, count);
341 
342         if (copy_from_user(&response, buf, count))
343                 return -EFAULT;
344 
345         ret = process_access_response(group, &response);
346         if (ret < 0)
347                 count = ret;
348 
349         return count;
350 #else
351         return -EINVAL;
352 #endif
353 }
354 
355 static int fanotify_release(struct inode *ignored, struct file *file)
356 {
357         struct fsnotify_group *group = file->private_data;
358 
359 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
360         struct fanotify_perm_event_info *event, *next;
361 
362         /*
363          * There may be still new events arriving in the notification queue
364          * but since userspace cannot use fanotify fd anymore, no event can
365          * enter or leave access_list by now.
366          */
367         spin_lock(&group->fanotify_data.access_lock);
368 
369         atomic_inc(&group->fanotify_data.bypass_perm);
370 
371         list_for_each_entry_safe(event, next, &group->fanotify_data.access_list,
372                                  fae.fse.list) {
373                 pr_debug("%s: found group=%p event=%p\n", __func__, group,
374                          event);
375 
376                 list_del_init(&event->fae.fse.list);
377                 event->response = FAN_ALLOW;
378         }
379         spin_unlock(&group->fanotify_data.access_lock);
380 
381         /*
382          * Since bypass_perm is set, newly queued events will not wait for
383          * access response. Wake up the already sleeping ones now.
384          * synchronize_srcu() in fsnotify_destroy_group() will wait for all
385          * processes sleeping in fanotify_handle_event() waiting for access
386          * response and thus also for all permission events to be freed.
387          */
388         wake_up(&group->fanotify_data.access_waitq);
389 #endif
390 
391         /* matches the fanotify_init->fsnotify_alloc_group */
392         fsnotify_destroy_group(group);
393 
394         return 0;
395 }
396 
397 static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
398 {
399         struct fsnotify_group *group;
400         struct fsnotify_event *fsn_event;
401         void __user *p;
402         int ret = -ENOTTY;
403         size_t send_len = 0;
404 
405         group = file->private_data;
406 
407         p = (void __user *) arg;
408 
409         switch (cmd) {
410         case FIONREAD:
411                 mutex_lock(&group->notification_mutex);
412                 list_for_each_entry(fsn_event, &group->notification_list, list)
413                         send_len += FAN_EVENT_METADATA_LEN;
414                 mutex_unlock(&group->notification_mutex);
415                 ret = put_user(send_len, (int __user *) p);
416                 break;
417         }
418 
419         return ret;
420 }
421 
422 static const struct file_operations fanotify_fops = {
423         .show_fdinfo    = fanotify_show_fdinfo,
424         .poll           = fanotify_poll,
425         .read           = fanotify_read,
426         .write          = fanotify_write,
427         .fasync         = NULL,
428         .release        = fanotify_release,
429         .unlocked_ioctl = fanotify_ioctl,
430         .compat_ioctl   = fanotify_ioctl,
431         .llseek         = noop_llseek,
432 };
433 
434 static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
435 {
436         kmem_cache_free(fanotify_mark_cache, fsn_mark);
437 }
438 
439 static int fanotify_find_path(int dfd, const char __user *filename,
440                               struct path *path, unsigned int flags)
441 {
442         int ret;
443 
444         pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__,
445                  dfd, filename, flags);
446 
447         if (filename == NULL) {
448                 struct fd f = fdget(dfd);
449 
450                 ret = -EBADF;
451                 if (!f.file)
452                         goto out;
453 
454                 ret = -ENOTDIR;
455                 if ((flags & FAN_MARK_ONLYDIR) &&
456                     !(S_ISDIR(file_inode(f.file)->i_mode))) {
457                         fdput(f);
458                         goto out;
459                 }
460 
461                 *path = f.file->f_path;
462                 path_get(path);
463                 fdput(f);
464         } else {
465                 unsigned int lookup_flags = 0;
466 
467                 if (!(flags & FAN_MARK_DONT_FOLLOW))
468                         lookup_flags |= LOOKUP_FOLLOW;
469                 if (flags & FAN_MARK_ONLYDIR)
470                         lookup_flags |= LOOKUP_DIRECTORY;
471 
472                 ret = user_path_at(dfd, filename, lookup_flags, path);
473                 if (ret)
474                         goto out;
475         }
476 
477         /* you can only watch an inode if you have read permissions on it */
478         ret = inode_permission(path->dentry->d_inode, MAY_READ);
479         if (ret)
480                 path_put(path);
481 out:
482         return ret;
483 }
484 
485 static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
486                                             __u32 mask,
487                                             unsigned int flags,
488                                             int *destroy)
489 {
490         __u32 oldmask = 0;
491 
492         spin_lock(&fsn_mark->lock);
493         if (!(flags & FAN_MARK_IGNORED_MASK)) {
494                 __u32 tmask = fsn_mark->mask & ~mask;
495 
496                 if (flags & FAN_MARK_ONDIR)
497                         tmask &= ~FAN_ONDIR;
498 
499                 oldmask = fsn_mark->mask;
500                 fsnotify_set_mark_mask_locked(fsn_mark, tmask);
501         } else {
502                 __u32 tmask = fsn_mark->ignored_mask & ~mask;
503                 if (flags & FAN_MARK_ONDIR)
504                         tmask &= ~FAN_ONDIR;
505 
506                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
507         }
508         *destroy = !(fsn_mark->mask | fsn_mark->ignored_mask);
509         spin_unlock(&fsn_mark->lock);
510 
511         return mask & oldmask;
512 }
513 
514 static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
515                                          struct vfsmount *mnt, __u32 mask,
516                                          unsigned int flags)
517 {
518         struct fsnotify_mark *fsn_mark = NULL;
519         __u32 removed;
520         int destroy_mark;
521 
522         mutex_lock(&group->mark_mutex);
523         fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
524         if (!fsn_mark) {
525                 mutex_unlock(&group->mark_mutex);
526                 return -ENOENT;
527         }
528 
529         removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags,
530                                                  &destroy_mark);
531         if (destroy_mark)
532                 fsnotify_detach_mark(fsn_mark);
533         mutex_unlock(&group->mark_mutex);
534         if (destroy_mark)
535                 fsnotify_free_mark(fsn_mark);
536 
537         fsnotify_put_mark(fsn_mark);
538         if (removed & real_mount(mnt)->mnt_fsnotify_mask)
539                 fsnotify_recalc_vfsmount_mask(mnt);
540 
541         return 0;
542 }
543 
544 static int fanotify_remove_inode_mark(struct fsnotify_group *group,
545                                       struct inode *inode, __u32 mask,
546                                       unsigned int flags)
547 {
548         struct fsnotify_mark *fsn_mark = NULL;
549         __u32 removed;
550         int destroy_mark;
551 
552         mutex_lock(&group->mark_mutex);
553         fsn_mark = fsnotify_find_inode_mark(group, inode);
554         if (!fsn_mark) {
555                 mutex_unlock(&group->mark_mutex);
556                 return -ENOENT;
557         }
558 
559         removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags,
560                                                  &destroy_mark);
561         if (destroy_mark)
562                 fsnotify_detach_mark(fsn_mark);
563         mutex_unlock(&group->mark_mutex);
564         if (destroy_mark)
565                 fsnotify_free_mark(fsn_mark);
566 
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                 __u32 tmask = fsn_mark->mask | mask;
584 
585                 if (flags & FAN_MARK_ONDIR)
586                         tmask |= FAN_ONDIR;
587 
588                 oldmask = fsn_mark->mask;
589                 fsnotify_set_mark_mask_locked(fsn_mark, tmask);
590         } else {
591                 __u32 tmask = fsn_mark->ignored_mask | mask;
592                 if (flags & FAN_MARK_ONDIR)
593                         tmask |= FAN_ONDIR;
594 
595                 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
596                 if (flags & FAN_MARK_IGNORED_SURV_MODIFY)
597                         fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
598         }
599         spin_unlock(&fsn_mark->lock);
600 
601         return mask & ~oldmask;
602 }
603 
604 static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
605                                                    struct inode *inode,
606                                                    struct vfsmount *mnt)
607 {
608         struct fsnotify_mark *mark;
609         int ret;
610 
611         if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
612                 return ERR_PTR(-ENOSPC);
613 
614         mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
615         if (!mark)
616                 return ERR_PTR(-ENOMEM);
617 
618         fsnotify_init_mark(mark, fanotify_free_mark);
619         ret = fsnotify_add_mark_locked(mark, group, inode, mnt, 0);
620         if (ret) {
621                 fsnotify_put_mark(mark);
622                 return ERR_PTR(ret);
623         }
624 
625         return mark;
626 }
627 
628 
629 static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
630                                       struct vfsmount *mnt, __u32 mask,
631                                       unsigned int flags)
632 {
633         struct fsnotify_mark *fsn_mark;
634         __u32 added;
635 
636         mutex_lock(&group->mark_mutex);
637         fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
638         if (!fsn_mark) {
639                 fsn_mark = fanotify_add_new_mark(group, NULL, mnt);
640                 if (IS_ERR(fsn_mark)) {
641                         mutex_unlock(&group->mark_mutex);
642                         return PTR_ERR(fsn_mark);
643                 }
644         }
645         added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
646         mutex_unlock(&group->mark_mutex);
647 
648         if (added & ~real_mount(mnt)->mnt_fsnotify_mask)
649                 fsnotify_recalc_vfsmount_mask(mnt);
650 
651         fsnotify_put_mark(fsn_mark);
652         return 0;
653 }
654 
655 static int fanotify_add_inode_mark(struct fsnotify_group *group,
656                                    struct inode *inode, __u32 mask,
657                                    unsigned int flags)
658 {
659         struct fsnotify_mark *fsn_mark;
660         __u32 added;
661 
662         pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
663 
664         /*
665          * If some other task has this inode open for write we should not add
666          * an ignored mark, unless that ignored mark is supposed to survive
667          * modification changes anyway.
668          */
669         if ((flags & FAN_MARK_IGNORED_MASK) &&
670             !(flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
671             (atomic_read(&inode->i_writecount) > 0))
672                 return 0;
673 
674         mutex_lock(&group->mark_mutex);
675         fsn_mark = fsnotify_find_inode_mark(group, inode);
676         if (!fsn_mark) {
677                 fsn_mark = fanotify_add_new_mark(group, inode, NULL);
678                 if (IS_ERR(fsn_mark)) {
679                         mutex_unlock(&group->mark_mutex);
680                         return PTR_ERR(fsn_mark);
681                 }
682         }
683         added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
684         mutex_unlock(&group->mark_mutex);
685 
686         if (added & ~inode->i_fsnotify_mask)
687                 fsnotify_recalc_inode_mask(inode);
688 
689         fsnotify_put_mark(fsn_mark);
690         return 0;
691 }
692 
693 /* fanotify syscalls */
694 SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
695 {
696         struct fsnotify_group *group;
697         int f_flags, fd;
698         struct user_struct *user;
699         struct fanotify_event_info *oevent;
700 
701         pr_debug("%s: flags=%d event_f_flags=%d\n",
702                 __func__, flags, event_f_flags);
703 
704         if (!capable(CAP_SYS_ADMIN))
705                 return -EPERM;
706 
707         if (flags & ~FAN_ALL_INIT_FLAGS)
708                 return -EINVAL;
709 
710         if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS)
711                 return -EINVAL;
712 
713         switch (event_f_flags & O_ACCMODE) {
714         case O_RDONLY:
715         case O_RDWR:
716         case O_WRONLY:
717                 break;
718         default:
719                 return -EINVAL;
720         }
721 
722         user = get_current_user();
723         if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {
724                 free_uid(user);
725                 return -EMFILE;
726         }
727 
728         f_flags = O_RDWR | FMODE_NONOTIFY;
729         if (flags & FAN_CLOEXEC)
730                 f_flags |= O_CLOEXEC;
731         if (flags & FAN_NONBLOCK)
732                 f_flags |= O_NONBLOCK;
733 
734         /* fsnotify_alloc_group takes a ref.  Dropped in fanotify_release */
735         group = fsnotify_alloc_group(&fanotify_fsnotify_ops);
736         if (IS_ERR(group)) {
737                 free_uid(user);
738                 return PTR_ERR(group);
739         }
740 
741         group->fanotify_data.user = user;
742         atomic_inc(&user->fanotify_listeners);
743 
744         oevent = fanotify_alloc_event(NULL, FS_Q_OVERFLOW, NULL);
745         if (unlikely(!oevent)) {
746                 fd = -ENOMEM;
747                 goto out_destroy_group;
748         }
749         group->overflow_event = &oevent->fse;
750 
751         if (force_o_largefile())
752                 event_f_flags |= O_LARGEFILE;
753         group->fanotify_data.f_flags = event_f_flags;
754 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
755         spin_lock_init(&group->fanotify_data.access_lock);
756         init_waitqueue_head(&group->fanotify_data.access_waitq);
757         INIT_LIST_HEAD(&group->fanotify_data.access_list);
758         atomic_set(&group->fanotify_data.bypass_perm, 0);
759 #endif
760         switch (flags & FAN_ALL_CLASS_BITS) {
761         case FAN_CLASS_NOTIF:
762                 group->priority = FS_PRIO_0;
763                 break;
764         case FAN_CLASS_CONTENT:
765                 group->priority = FS_PRIO_1;
766                 break;
767         case FAN_CLASS_PRE_CONTENT:
768                 group->priority = FS_PRIO_2;
769                 break;
770         default:
771                 fd = -EINVAL;
772                 goto out_destroy_group;
773         }
774 
775         if (flags & FAN_UNLIMITED_QUEUE) {
776                 fd = -EPERM;
777                 if (!capable(CAP_SYS_ADMIN))
778                         goto out_destroy_group;
779                 group->max_events = UINT_MAX;
780         } else {
781                 group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS;
782         }
783 
784         if (flags & FAN_UNLIMITED_MARKS) {
785                 fd = -EPERM;
786                 if (!capable(CAP_SYS_ADMIN))
787                         goto out_destroy_group;
788                 group->fanotify_data.max_marks = UINT_MAX;
789         } else {
790                 group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS;
791         }
792 
793         fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
794         if (fd < 0)
795                 goto out_destroy_group;
796 
797         return fd;
798 
799 out_destroy_group:
800         fsnotify_destroy_group(group);
801         return fd;
802 }
803 
804 SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags,
805                               __u64, mask, int, dfd,
806                               const char  __user *, pathname)
807 {
808         struct inode *inode = NULL;
809         struct vfsmount *mnt = NULL;
810         struct fsnotify_group *group;
811         struct fd f;
812         struct path path;
813         int ret;
814 
815         pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
816                  __func__, fanotify_fd, flags, dfd, pathname, mask);
817 
818         /* we only use the lower 32 bits as of right now. */
819         if (mask & ((__u64)0xffffffff << 32))
820                 return -EINVAL;
821 
822         if (flags & ~FAN_ALL_MARK_FLAGS)
823                 return -EINVAL;
824         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
825         case FAN_MARK_ADD:              /* fallthrough */
826         case FAN_MARK_REMOVE:
827                 if (!mask)
828                         return -EINVAL;
829                 break;
830         case FAN_MARK_FLUSH:
831                 if (flags & ~(FAN_MARK_MOUNT | FAN_MARK_FLUSH))
832                         return -EINVAL;
833                 break;
834         default:
835                 return -EINVAL;
836         }
837 
838         if (mask & FAN_ONDIR) {
839                 flags |= FAN_MARK_ONDIR;
840                 mask &= ~FAN_ONDIR;
841         }
842 
843 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
844         if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD))
845 #else
846         if (mask & ~(FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD))
847 #endif
848                 return -EINVAL;
849 
850         f = fdget(fanotify_fd);
851         if (unlikely(!f.file))
852                 return -EBADF;
853 
854         /* verify that this is indeed an fanotify instance */
855         ret = -EINVAL;
856         if (unlikely(f.file->f_op != &fanotify_fops))
857                 goto fput_and_out;
858         group = f.file->private_data;
859 
860         /*
861          * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF.  These are not
862          * allowed to set permissions events.
863          */
864         ret = -EINVAL;
865         if (mask & FAN_ALL_PERM_EVENTS &&
866             group->priority == FS_PRIO_0)
867                 goto fput_and_out;
868 
869         if (flags & FAN_MARK_FLUSH) {
870                 ret = 0;
871                 if (flags & FAN_MARK_MOUNT)
872                         fsnotify_clear_vfsmount_marks_by_group(group);
873                 else
874                         fsnotify_clear_inode_marks_by_group(group);
875                 goto fput_and_out;
876         }
877 
878         ret = fanotify_find_path(dfd, pathname, &path, flags);
879         if (ret)
880                 goto fput_and_out;
881 
882         /* inode held in place by reference to path; group by fget on fd */
883         if (!(flags & FAN_MARK_MOUNT))
884                 inode = path.dentry->d_inode;
885         else
886                 mnt = path.mnt;
887 
888         /* create/update an inode mark */
889         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) {
890         case FAN_MARK_ADD:
891                 if (flags & FAN_MARK_MOUNT)
892                         ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags);
893                 else
894                         ret = fanotify_add_inode_mark(group, inode, mask, flags);
895                 break;
896         case FAN_MARK_REMOVE:
897                 if (flags & FAN_MARK_MOUNT)
898                         ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags);
899                 else
900                         ret = fanotify_remove_inode_mark(group, inode, mask, flags);
901                 break;
902         default:
903                 ret = -EINVAL;
904         }
905 
906         path_put(&path);
907 fput_and_out:
908         fdput(f);
909         return ret;
910 }
911 
912 #ifdef CONFIG_COMPAT
913 COMPAT_SYSCALL_DEFINE6(fanotify_mark,
914                                 int, fanotify_fd, unsigned int, flags,
915                                 __u32, mask0, __u32, mask1, int, dfd,
916                                 const char  __user *, pathname)
917 {
918         return sys_fanotify_mark(fanotify_fd, flags,
919 #ifdef __BIG_ENDIAN
920                                 ((__u64)mask0 << 32) | mask1,
921 #else
922                                 ((__u64)mask1 << 32) | mask0,
923 #endif
924                                  dfd, pathname);
925 }
926 #endif
927 
928 /*
929  * fanotify_user_setup - Our initialization function.  Note that we cannot return
930  * error because we have compiled-in VFS hooks.  So an (unlikely) failure here
931  * must result in panic().
932  */
933 static int __init fanotify_user_setup(void)
934 {
935         fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC);
936         fanotify_event_cachep = KMEM_CACHE(fanotify_event_info, SLAB_PANIC);
937 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
938         fanotify_perm_event_cachep = KMEM_CACHE(fanotify_perm_event_info,
939                                                 SLAB_PANIC);
940 #endif
941 
942         return 0;
943 }
944 device_initcall(fanotify_user_setup);
945 

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