1 #include <linux/fcntl.h>
2 #include <linux/file.h>
4 #include <linux/anon_inodes.h>
5 #include <linux/fsnotify_backend.h>
6 #include <linux/init.h>
7 #include <linux/mount.h>
8 #include <linux/namei.h>
9 #include <linux/poll.h>
10 #include <linux/security.h>
11 #include <linux/syscalls.h>
12 #include <linux/types.h>
13 #include <linux/uaccess.h>
15 #include <asm/ioctls.h>
19 static struct kmem_cache *fanotify_mark_cache __read_mostly;
22 * Get an fsnotify notification event if one exists and is small
23 * enough to fit in "count". Return an error pointer if the count
24 * is not large enough.
26 * Called with the group->notification_mutex held.
28 static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
31 BUG_ON(!mutex_is_locked(&group->notification_mutex));
33 pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
35 if (fsnotify_notify_queue_is_empty(group))
38 if (FAN_EVENT_METADATA_LEN > count)
39 return ERR_PTR(-EINVAL);
41 /* held the notification_mutex the whole time, so this is the
42 * same event we peeked above */
43 return fsnotify_remove_notify_event(group);
46 static int create_fd(struct fsnotify_group *group, struct fsnotify_event *event)
49 struct dentry *dentry;
51 struct file *new_file;
53 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
55 client_fd = get_unused_fd();
59 if (event->data_type != FSNOTIFY_EVENT_PATH) {
61 put_unused_fd(client_fd);
66 * we need a new file handle for the userspace program so it can read even if it was
67 * originally opened O_WRONLY.
69 dentry = dget(event->path.dentry);
70 mnt = mntget(event->path.mnt);
71 /* it's possible this event was an overflow event. in that case dentry and mnt
72 * are NULL; That's fine, just don't call dentry open */
74 new_file = dentry_open(dentry, mnt,
75 O_RDONLY | O_LARGEFILE | FMODE_NONOTIFY,
78 new_file = ERR_PTR(-EOVERFLOW);
79 if (IS_ERR(new_file)) {
81 * we still send an event even if we can't open the file. this
82 * can happen when say tasks are gone and we try to open their
83 * /proc files or we try to open a WRONLY file like in sysfs
84 * we just send the errno to userspace since there isn't much
87 put_unused_fd(client_fd);
88 client_fd = PTR_ERR(new_file);
90 fd_install(client_fd, new_file);
96 static ssize_t fill_event_metadata(struct fsnotify_group *group,
97 struct fanotify_event_metadata *metadata,
98 struct fsnotify_event *event)
100 pr_debug("%s: group=%p metadata=%p event=%p\n", __func__,
101 group, metadata, event);
103 metadata->event_len = FAN_EVENT_METADATA_LEN;
104 metadata->vers = FANOTIFY_METADATA_VERSION;
105 metadata->mask = fanotify_outgoing_mask(event->mask);
106 metadata->pid = pid_vnr(event->tgid);
107 metadata->fd = create_fd(group, event);
112 static ssize_t copy_event_to_user(struct fsnotify_group *group,
113 struct fsnotify_event *event,
116 struct fanotify_event_metadata fanotify_event_metadata;
119 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
121 ret = fill_event_metadata(group, &fanotify_event_metadata, event);
125 if (copy_to_user(buf, &fanotify_event_metadata, FAN_EVENT_METADATA_LEN))
128 return FAN_EVENT_METADATA_LEN;
131 /* intofiy userspace file descriptor functions */
132 static unsigned int fanotify_poll(struct file *file, poll_table *wait)
134 struct fsnotify_group *group = file->private_data;
137 poll_wait(file, &group->notification_waitq, wait);
138 mutex_lock(&group->notification_mutex);
139 if (!fsnotify_notify_queue_is_empty(group))
140 ret = POLLIN | POLLRDNORM;
141 mutex_unlock(&group->notification_mutex);
146 static ssize_t fanotify_read(struct file *file, char __user *buf,
147 size_t count, loff_t *pos)
149 struct fsnotify_group *group;
150 struct fsnotify_event *kevent;
156 group = file->private_data;
158 pr_debug("%s: group=%p\n", __func__, group);
161 prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE);
163 mutex_lock(&group->notification_mutex);
164 kevent = get_one_event(group, count);
165 mutex_unlock(&group->notification_mutex);
168 ret = PTR_ERR(kevent);
171 ret = copy_event_to_user(group, kevent, buf);
172 fsnotify_put_event(kevent);
181 if (file->f_flags & O_NONBLOCK)
184 if (signal_pending(current))
193 finish_wait(&group->notification_waitq, &wait);
194 if (start != buf && ret != -EFAULT)
199 static int fanotify_release(struct inode *ignored, struct file *file)
201 struct fsnotify_group *group = file->private_data;
203 pr_debug("%s: file=%p group=%p\n", __func__, file, group);
205 /* matches the fanotify_init->fsnotify_alloc_group */
206 fsnotify_put_group(group);
211 static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
213 struct fsnotify_group *group;
214 struct fsnotify_event_holder *holder;
219 group = file->private_data;
221 p = (void __user *) arg;
225 mutex_lock(&group->notification_mutex);
226 list_for_each_entry(holder, &group->notification_list, event_list)
227 send_len += FAN_EVENT_METADATA_LEN;
228 mutex_unlock(&group->notification_mutex);
229 ret = put_user(send_len, (int __user *) p);
236 static const struct file_operations fanotify_fops = {
237 .poll = fanotify_poll,
238 .read = fanotify_read,
240 .release = fanotify_release,
241 .unlocked_ioctl = fanotify_ioctl,
242 .compat_ioctl = fanotify_ioctl,
245 static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
247 kmem_cache_free(fanotify_mark_cache, fsn_mark);
250 static int fanotify_find_path(int dfd, const char __user *filename,
251 struct path *path, unsigned int flags)
255 pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__,
256 dfd, filename, flags);
258 if (filename == NULL) {
263 file = fget_light(dfd, &fput_needed);
268 if ((flags & FAN_MARK_ONLYDIR) &&
269 !(S_ISDIR(file->f_path.dentry->d_inode->i_mode))) {
270 fput_light(file, fput_needed);
274 *path = file->f_path;
276 fput_light(file, fput_needed);
278 unsigned int lookup_flags = 0;
280 if (!(flags & FAN_MARK_DONT_FOLLOW))
281 lookup_flags |= LOOKUP_FOLLOW;
282 if (flags & FAN_MARK_ONLYDIR)
283 lookup_flags |= LOOKUP_DIRECTORY;
285 ret = user_path_at(dfd, filename, lookup_flags, path);
290 /* you can only watch an inode if you have read permissions on it */
291 ret = inode_permission(path->dentry->d_inode, MAY_READ);
298 static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, __u32 mask)
302 spin_lock(&fsn_mark->lock);
303 oldmask = fsn_mark->mask;
304 fsn_mark->mask = oldmask & ~mask;
305 spin_unlock(&fsn_mark->lock);
307 if (!(oldmask & ~mask))
308 fsnotify_destroy_mark(fsn_mark);
310 return mask & oldmask;
313 static int fanotify_remove_mark(struct fsnotify_group *group, struct inode *inode,
314 struct vfsmount *mnt, __u32 mask)
316 struct fsnotify_mark *fsn_mark = NULL;
319 BUG_ON(inode && mnt);
320 BUG_ON(!inode && !mnt);
323 fsn_mark = fsnotify_find_inode_mark(group, inode);
325 fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
332 removed = fanotify_mark_remove_from_mask(fsn_mark, mask);
333 /* matches the fsnotify_find_inode_mark() */
334 fsnotify_put_mark(fsn_mark);
336 if (removed & group->mask)
337 fsnotify_recalc_group_mask(group);
339 if (removed & inode->i_fsnotify_mask)
340 fsnotify_recalc_inode_mask(inode);
342 if (removed & mnt->mnt_fsnotify_mask)
343 fsnotify_recalc_vfsmount_mask(mnt);
349 static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, __u32 mask)
353 spin_lock(&fsn_mark->lock);
354 oldmask = fsn_mark->mask;
355 fsn_mark->mask = oldmask | mask;
356 spin_unlock(&fsn_mark->lock);
358 return mask & ~oldmask;
361 static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
362 struct vfsmount *mnt, __u32 mask)
364 struct fsnotify_mark *fsn_mark;
367 fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
371 fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
375 fsnotify_init_mark(fsn_mark, fanotify_free_mark);
376 ret = fsnotify_add_mark(fsn_mark, group, NULL, mnt, 0);
378 fanotify_free_mark(fsn_mark);
382 added = fanotify_mark_add_to_mask(fsn_mark, mask);
383 fsnotify_put_mark(fsn_mark);
385 if (added & ~group->mask)
386 fsnotify_recalc_group_mask(group);
387 if (added & ~mnt->mnt_fsnotify_mask)
388 fsnotify_recalc_vfsmount_mask(mnt);
393 static int fanotify_add_inode_mark(struct fsnotify_group *group,
394 struct inode *inode, __u32 mask)
396 struct fsnotify_mark *fsn_mark;
399 pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
401 fsn_mark = fsnotify_find_inode_mark(group, inode);
405 fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
409 fsnotify_init_mark(fsn_mark, fanotify_free_mark);
410 ret = fsnotify_add_mark(fsn_mark, group, inode, NULL, 0);
412 fanotify_free_mark(fsn_mark);
416 added = fanotify_mark_add_to_mask(fsn_mark, mask);
417 fsnotify_put_mark(fsn_mark);
419 if (added & ~group->mask)
420 fsnotify_recalc_group_mask(group);
421 if (added & ~inode->i_fsnotify_mask)
422 fsnotify_recalc_inode_mask(inode);
427 static bool fanotify_mark_validate_input(int flags,
430 pr_debug("%s: flags=%x mask=%x\n", __func__, flags, mask);
432 /* are flags valid of this operation? */
433 if (!fanotify_mark_flags_valid(flags))
435 /* is the mask valid? */
436 if (!fanotify_mask_valid(mask))
441 /* fanotify syscalls */
442 SYSCALL_DEFINE3(fanotify_init, unsigned int, flags, unsigned int, event_f_flags,
443 unsigned int, priority)
445 struct fsnotify_group *group;
448 pr_debug("%s: flags=%d event_f_flags=%d priority=%d\n",
449 __func__, flags, event_f_flags, priority);
456 if (!capable(CAP_SYS_ADMIN))
459 if (flags & ~FAN_ALL_INIT_FLAGS)
462 f_flags = (O_RDONLY | FMODE_NONOTIFY);
463 if (flags & FAN_CLOEXEC)
464 f_flags |= O_CLOEXEC;
465 if (flags & FAN_NONBLOCK)
466 f_flags |= O_NONBLOCK;
468 /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */
469 group = fsnotify_alloc_group(&fanotify_fsnotify_ops);
471 return PTR_ERR(group);
473 fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
480 fsnotify_put_group(group);
484 SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
486 const char __user * pathname)
488 struct inode *inode = NULL;
489 struct vfsmount *mnt = NULL;
490 struct fsnotify_group *group;
493 int ret, fput_needed;
495 pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
496 __func__, fanotify_fd, flags, dfd, pathname, mask);
498 /* we only use the lower 32 bits as of right now. */
499 if (mask & ((__u64)0xffffffff << 32))
502 if (!fanotify_mark_validate_input(flags, mask))
505 filp = fget_light(fanotify_fd, &fput_needed);
509 /* verify that this is indeed an fanotify instance */
511 if (unlikely(filp->f_op != &fanotify_fops))
514 ret = fanotify_find_path(dfd, pathname, &path, flags);
518 /* inode held in place by reference to path; group by fget on fd */
519 if (!(flags & FAN_MARK_ON_VFSMOUNT))
520 inode = path.dentry->d_inode;
523 group = filp->private_data;
525 /* create/update an inode mark */
526 switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) {
528 if (flags & FAN_MARK_ON_VFSMOUNT)
529 ret = fanotify_add_vfsmount_mark(group, mnt, mask);
531 ret = fanotify_add_inode_mark(group, inode, mask);
533 case FAN_MARK_REMOVE:
534 ret = fanotify_remove_mark(group, inode, mnt, mask);
542 fput_light(filp, fput_needed);
546 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
547 asmlinkage long SyS_fanotify_mark(long fanotify_fd, long flags, __u64 mask,
548 long dfd, long pathname)
550 return SYSC_fanotify_mark((int) fanotify_fd, (unsigned int) flags,
552 (const char __user *) pathname);
554 SYSCALL_ALIAS(sys_fanotify_mark, SyS_fanotify_mark);
558 * fanotify_user_setup - Our initialization function. Note that we cannnot return
559 * error because we have compiled-in VFS hooks. So an (unlikely) failure here
560 * must result in panic().
562 static int __init fanotify_user_setup(void)
564 fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC);
568 device_initcall(fanotify_user_setup);