Commit | Line | Data |
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2d9048e2 AG |
1 | /* |
2 | * fs/inotify_user.c - inotify support for userspace | |
3 | * | |
4 | * Authors: | |
5 | * John McCutchan <ttb@tentacle.dhs.org> | |
6 | * Robert Love <rml@novell.com> | |
7 | * | |
8 | * Copyright (C) 2005 John McCutchan | |
9 | * Copyright 2006 Hewlett-Packard Development Company, L.P. | |
10 | * | |
63c882a0 EP |
11 | * Copyright (C) 2009 Eric Paris <Red Hat Inc> |
12 | * inotify was largely rewriten to make use of the fsnotify infrastructure | |
13 | * | |
2d9048e2 AG |
14 | * This program is free software; you can redistribute it and/or modify it |
15 | * under the terms of the GNU General Public License as published by the | |
16 | * Free Software Foundation; either version 2, or (at your option) any | |
17 | * later version. | |
18 | * | |
19 | * This program is distributed in the hope that it will be useful, but | |
20 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
22 | * General Public License for more details. | |
23 | */ | |
24 | ||
2d9048e2 | 25 | #include <linux/file.h> |
63c882a0 EP |
26 | #include <linux/fs.h> /* struct inode */ |
27 | #include <linux/fsnotify_backend.h> | |
28 | #include <linux/idr.h> | |
29 | #include <linux/init.h> /* module_init */ | |
2d9048e2 | 30 | #include <linux/inotify.h> |
63c882a0 EP |
31 | #include <linux/kernel.h> /* roundup() */ |
32 | #include <linux/magic.h> /* superblock magic number */ | |
33 | #include <linux/mount.h> /* mntget */ | |
34 | #include <linux/namei.h> /* LOOKUP_FOLLOW */ | |
35 | #include <linux/path.h> /* struct path */ | |
36 | #include <linux/sched.h> /* struct user */ | |
37 | #include <linux/slab.h> /* struct kmem_cache */ | |
2d9048e2 | 38 | #include <linux/syscalls.h> |
63c882a0 EP |
39 | #include <linux/types.h> |
40 | #include <linux/uaccess.h> | |
41 | #include <linux/poll.h> | |
42 | #include <linux/wait.h> | |
2d9048e2 | 43 | |
63c882a0 | 44 | #include "inotify.h" |
2d9048e2 | 45 | |
63c882a0 | 46 | #include <asm/ioctls.h> |
2d9048e2 AG |
47 | |
48 | static struct vfsmount *inotify_mnt __read_mostly; | |
49 | ||
50 | /* these are configurable via /proc/sys/fs/inotify/ */ | |
3c828e49 | 51 | static int inotify_max_user_instances __read_mostly; |
3c828e49 | 52 | static int inotify_max_queued_events __read_mostly; |
63c882a0 | 53 | int inotify_max_user_watches __read_mostly; |
2d9048e2 | 54 | |
63c882a0 EP |
55 | static struct kmem_cache *inotify_inode_mark_cachep __read_mostly; |
56 | struct kmem_cache *event_priv_cachep __read_mostly; | |
2d9048e2 AG |
57 | |
58 | /* | |
63c882a0 EP |
59 | * When inotify registers a new group it increments this and uses that |
60 | * value as an offset to set the fsnotify group "name" and priority. | |
2d9048e2 | 61 | */ |
63c882a0 | 62 | static atomic_t inotify_grp_num; |
2d9048e2 AG |
63 | |
64 | #ifdef CONFIG_SYSCTL | |
65 | ||
66 | #include <linux/sysctl.h> | |
67 | ||
68 | static int zero; | |
69 | ||
70 | ctl_table inotify_table[] = { | |
71 | { | |
2d9048e2 AG |
72 | .procname = "max_user_instances", |
73 | .data = &inotify_max_user_instances, | |
74 | .maxlen = sizeof(int), | |
75 | .mode = 0644, | |
6d456111 | 76 | .proc_handler = proc_dointvec_minmax, |
2d9048e2 AG |
77 | .extra1 = &zero, |
78 | }, | |
79 | { | |
2d9048e2 AG |
80 | .procname = "max_user_watches", |
81 | .data = &inotify_max_user_watches, | |
82 | .maxlen = sizeof(int), | |
83 | .mode = 0644, | |
6d456111 | 84 | .proc_handler = proc_dointvec_minmax, |
2d9048e2 AG |
85 | .extra1 = &zero, |
86 | }, | |
87 | { | |
2d9048e2 AG |
88 | .procname = "max_queued_events", |
89 | .data = &inotify_max_queued_events, | |
90 | .maxlen = sizeof(int), | |
91 | .mode = 0644, | |
6d456111 | 92 | .proc_handler = proc_dointvec_minmax, |
2d9048e2 AG |
93 | .extra1 = &zero |
94 | }, | |
ab09203e | 95 | { } |
2d9048e2 AG |
96 | }; |
97 | #endif /* CONFIG_SYSCTL */ | |
98 | ||
63c882a0 | 99 | static inline __u32 inotify_arg_to_mask(u32 arg) |
1c17d18e | 100 | { |
63c882a0 | 101 | __u32 mask; |
1c17d18e | 102 | |
63c882a0 EP |
103 | /* everything should accept their own ignored and cares about children */ |
104 | mask = (FS_IN_IGNORED | FS_EVENT_ON_CHILD); | |
2d9048e2 | 105 | |
63c882a0 EP |
106 | /* mask off the flags used to open the fd */ |
107 | mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT)); | |
2d9048e2 | 108 | |
63c882a0 | 109 | return mask; |
2d9048e2 AG |
110 | } |
111 | ||
63c882a0 | 112 | static inline u32 inotify_mask_to_arg(__u32 mask) |
2d9048e2 | 113 | { |
63c882a0 EP |
114 | return mask & (IN_ALL_EVENTS | IN_ISDIR | IN_UNMOUNT | IN_IGNORED | |
115 | IN_Q_OVERFLOW); | |
2d9048e2 AG |
116 | } |
117 | ||
63c882a0 | 118 | /* intofiy userspace file descriptor functions */ |
2d9048e2 AG |
119 | static unsigned int inotify_poll(struct file *file, poll_table *wait) |
120 | { | |
63c882a0 | 121 | struct fsnotify_group *group = file->private_data; |
2d9048e2 AG |
122 | int ret = 0; |
123 | ||
63c882a0 EP |
124 | poll_wait(file, &group->notification_waitq, wait); |
125 | mutex_lock(&group->notification_mutex); | |
126 | if (!fsnotify_notify_queue_is_empty(group)) | |
2d9048e2 | 127 | ret = POLLIN | POLLRDNORM; |
63c882a0 | 128 | mutex_unlock(&group->notification_mutex); |
2d9048e2 AG |
129 | |
130 | return ret; | |
131 | } | |
132 | ||
3632dee2 VN |
133 | /* |
134 | * Get an inotify_kernel_event if one exists and is small | |
135 | * enough to fit in "count". Return an error pointer if | |
136 | * not large enough. | |
137 | * | |
63c882a0 | 138 | * Called with the group->notification_mutex held. |
3632dee2 | 139 | */ |
63c882a0 EP |
140 | static struct fsnotify_event *get_one_event(struct fsnotify_group *group, |
141 | size_t count) | |
3632dee2 VN |
142 | { |
143 | size_t event_size = sizeof(struct inotify_event); | |
63c882a0 | 144 | struct fsnotify_event *event; |
3632dee2 | 145 | |
63c882a0 | 146 | if (fsnotify_notify_queue_is_empty(group)) |
3632dee2 VN |
147 | return NULL; |
148 | ||
63c882a0 EP |
149 | event = fsnotify_peek_notify_event(group); |
150 | ||
83cb10f0 EP |
151 | if (event->name_len) |
152 | event_size += roundup(event->name_len + 1, event_size); | |
3632dee2 VN |
153 | |
154 | if (event_size > count) | |
155 | return ERR_PTR(-EINVAL); | |
156 | ||
63c882a0 EP |
157 | /* held the notification_mutex the whole time, so this is the |
158 | * same event we peeked above */ | |
159 | fsnotify_remove_notify_event(group); | |
160 | ||
161 | return event; | |
3632dee2 VN |
162 | } |
163 | ||
164 | /* | |
165 | * Copy an event to user space, returning how much we copied. | |
166 | * | |
167 | * We already checked that the event size is smaller than the | |
168 | * buffer we had in "get_one_event()" above. | |
169 | */ | |
63c882a0 EP |
170 | static ssize_t copy_event_to_user(struct fsnotify_group *group, |
171 | struct fsnotify_event *event, | |
3632dee2 VN |
172 | char __user *buf) |
173 | { | |
63c882a0 EP |
174 | struct inotify_event inotify_event; |
175 | struct fsnotify_event_private_data *fsn_priv; | |
176 | struct inotify_event_private_data *priv; | |
3632dee2 | 177 | size_t event_size = sizeof(struct inotify_event); |
b962e731 | 178 | size_t name_len = 0; |
63c882a0 EP |
179 | |
180 | /* we get the inotify watch descriptor from the event private data */ | |
181 | spin_lock(&event->lock); | |
182 | fsn_priv = fsnotify_remove_priv_from_event(group, event); | |
183 | spin_unlock(&event->lock); | |
184 | ||
185 | if (!fsn_priv) | |
186 | inotify_event.wd = -1; | |
187 | else { | |
188 | priv = container_of(fsn_priv, struct inotify_event_private_data, | |
189 | fsnotify_event_priv_data); | |
190 | inotify_event.wd = priv->wd; | |
191 | inotify_free_event_priv(fsn_priv); | |
192 | } | |
193 | ||
b962e731 BR |
194 | /* |
195 | * round up event->name_len so it is a multiple of event_size | |
0db501bd EB |
196 | * plus an extra byte for the terminating '\0'. |
197 | */ | |
b962e731 BR |
198 | if (event->name_len) |
199 | name_len = roundup(event->name_len + 1, event_size); | |
63c882a0 EP |
200 | inotify_event.len = name_len; |
201 | ||
202 | inotify_event.mask = inotify_mask_to_arg(event->mask); | |
203 | inotify_event.cookie = event->sync_cookie; | |
3632dee2 | 204 | |
63c882a0 EP |
205 | /* send the main event */ |
206 | if (copy_to_user(buf, &inotify_event, event_size)) | |
3632dee2 VN |
207 | return -EFAULT; |
208 | ||
63c882a0 | 209 | buf += event_size; |
3632dee2 | 210 | |
63c882a0 EP |
211 | /* |
212 | * fsnotify only stores the pathname, so here we have to send the pathname | |
213 | * and then pad that pathname out to a multiple of sizeof(inotify_event) | |
214 | * with zeros. I get my zeros from the nul_inotify_event. | |
215 | */ | |
216 | if (name_len) { | |
217 | unsigned int len_to_zero = name_len - event->name_len; | |
218 | /* copy the path name */ | |
219 | if (copy_to_user(buf, event->file_name, event->name_len)) | |
3632dee2 | 220 | return -EFAULT; |
63c882a0 | 221 | buf += event->name_len; |
3632dee2 | 222 | |
0db501bd EB |
223 | /* fill userspace with 0's */ |
224 | if (clear_user(buf, len_to_zero)) | |
63c882a0 EP |
225 | return -EFAULT; |
226 | buf += len_to_zero; | |
227 | event_size += name_len; | |
3632dee2 | 228 | } |
63c882a0 | 229 | |
3632dee2 VN |
230 | return event_size; |
231 | } | |
232 | ||
2d9048e2 AG |
233 | static ssize_t inotify_read(struct file *file, char __user *buf, |
234 | size_t count, loff_t *pos) | |
235 | { | |
63c882a0 EP |
236 | struct fsnotify_group *group; |
237 | struct fsnotify_event *kevent; | |
2d9048e2 AG |
238 | char __user *start; |
239 | int ret; | |
240 | DEFINE_WAIT(wait); | |
241 | ||
242 | start = buf; | |
63c882a0 | 243 | group = file->private_data; |
2d9048e2 AG |
244 | |
245 | while (1) { | |
63c882a0 | 246 | prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE); |
2d9048e2 | 247 | |
63c882a0 EP |
248 | mutex_lock(&group->notification_mutex); |
249 | kevent = get_one_event(group, count); | |
250 | mutex_unlock(&group->notification_mutex); | |
2d9048e2 | 251 | |
3632dee2 VN |
252 | if (kevent) { |
253 | ret = PTR_ERR(kevent); | |
254 | if (IS_ERR(kevent)) | |
255 | break; | |
63c882a0 EP |
256 | ret = copy_event_to_user(group, kevent, buf); |
257 | fsnotify_put_event(kevent); | |
3632dee2 VN |
258 | if (ret < 0) |
259 | break; | |
260 | buf += ret; | |
261 | count -= ret; | |
262 | continue; | |
2d9048e2 AG |
263 | } |
264 | ||
3632dee2 VN |
265 | ret = -EAGAIN; |
266 | if (file->f_flags & O_NONBLOCK) | |
2d9048e2 | 267 | break; |
3632dee2 VN |
268 | ret = -EINTR; |
269 | if (signal_pending(current)) | |
2d9048e2 | 270 | break; |
16dbc6c9 | 271 | |
3632dee2 | 272 | if (start != buf) |
2d9048e2 | 273 | break; |
16dbc6c9 | 274 | |
3632dee2 | 275 | schedule(); |
2d9048e2 | 276 | } |
2d9048e2 | 277 | |
63c882a0 | 278 | finish_wait(&group->notification_waitq, &wait); |
3632dee2 VN |
279 | if (start != buf && ret != -EFAULT) |
280 | ret = buf - start; | |
2d9048e2 AG |
281 | return ret; |
282 | } | |
283 | ||
bcfbf84d DA |
284 | static int inotify_fasync(int fd, struct file *file, int on) |
285 | { | |
63c882a0 | 286 | struct fsnotify_group *group = file->private_data; |
bcfbf84d | 287 | |
63c882a0 | 288 | return fasync_helper(fd, file, on, &group->inotify_data.fa) >= 0 ? 0 : -EIO; |
bcfbf84d DA |
289 | } |
290 | ||
2d9048e2 AG |
291 | static int inotify_release(struct inode *ignored, struct file *file) |
292 | { | |
63c882a0 | 293 | struct fsnotify_group *group = file->private_data; |
bdae997f | 294 | struct user_struct *user = group->inotify_data.user; |
2d9048e2 | 295 | |
63c882a0 | 296 | fsnotify_clear_marks_by_group(group); |
2d9048e2 | 297 | |
63c882a0 EP |
298 | /* free this group, matching get was inotify_init->fsnotify_obtain_group */ |
299 | fsnotify_put_group(group); | |
2d9048e2 | 300 | |
bdae997f KP |
301 | atomic_dec(&user->inotify_devs); |
302 | ||
2d9048e2 AG |
303 | return 0; |
304 | } | |
305 | ||
306 | static long inotify_ioctl(struct file *file, unsigned int cmd, | |
307 | unsigned long arg) | |
308 | { | |
63c882a0 EP |
309 | struct fsnotify_group *group; |
310 | struct fsnotify_event_holder *holder; | |
311 | struct fsnotify_event *event; | |
2d9048e2 AG |
312 | void __user *p; |
313 | int ret = -ENOTTY; | |
63c882a0 | 314 | size_t send_len = 0; |
2d9048e2 | 315 | |
63c882a0 | 316 | group = file->private_data; |
2d9048e2 AG |
317 | p = (void __user *) arg; |
318 | ||
319 | switch (cmd) { | |
320 | case FIONREAD: | |
63c882a0 EP |
321 | mutex_lock(&group->notification_mutex); |
322 | list_for_each_entry(holder, &group->notification_list, event_list) { | |
323 | event = holder->event; | |
324 | send_len += sizeof(struct inotify_event); | |
83cb10f0 EP |
325 | if (event->name_len) |
326 | send_len += roundup(event->name_len + 1, | |
327 | sizeof(struct inotify_event)); | |
63c882a0 EP |
328 | } |
329 | mutex_unlock(&group->notification_mutex); | |
330 | ret = put_user(send_len, (int __user *) p); | |
2d9048e2 AG |
331 | break; |
332 | } | |
333 | ||
334 | return ret; | |
335 | } | |
336 | ||
337 | static const struct file_operations inotify_fops = { | |
63c882a0 EP |
338 | .poll = inotify_poll, |
339 | .read = inotify_read, | |
340 | .fasync = inotify_fasync, | |
341 | .release = inotify_release, | |
342 | .unlocked_ioctl = inotify_ioctl, | |
2d9048e2 AG |
343 | .compat_ioctl = inotify_ioctl, |
344 | }; | |
345 | ||
2d9048e2 | 346 | |
63c882a0 EP |
347 | /* |
348 | * find_inode - resolve a user-given path to a specific inode | |
349 | */ | |
350 | static int inotify_find_inode(const char __user *dirname, struct path *path, unsigned flags) | |
351 | { | |
352 | int error; | |
353 | ||
354 | error = user_path_at(AT_FDCWD, dirname, flags, path); | |
355 | if (error) | |
356 | return error; | |
357 | /* you can only watch an inode if you have read permissions on it */ | |
358 | error = inode_permission(path->dentry->d_inode, MAY_READ); | |
359 | if (error) | |
360 | path_put(path); | |
361 | return error; | |
362 | } | |
363 | ||
dead537d EP |
364 | /* |
365 | * Remove the mark from the idr (if present) and drop the reference | |
366 | * on the mark because it was in the idr. | |
367 | */ | |
7e790dd5 EP |
368 | static void inotify_remove_from_idr(struct fsnotify_group *group, |
369 | struct inotify_inode_mark_entry *ientry) | |
370 | { | |
371 | struct idr *idr; | |
dead537d EP |
372 | struct fsnotify_mark_entry *entry; |
373 | struct inotify_inode_mark_entry *found_ientry; | |
374 | int wd; | |
7e790dd5 EP |
375 | |
376 | spin_lock(&group->inotify_data.idr_lock); | |
377 | idr = &group->inotify_data.idr; | |
dead537d EP |
378 | wd = ientry->wd; |
379 | ||
380 | if (wd == -1) | |
381 | goto out; | |
382 | ||
383 | entry = idr_find(&group->inotify_data.idr, wd); | |
384 | if (unlikely(!entry)) | |
385 | goto out; | |
386 | ||
387 | found_ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry); | |
388 | if (unlikely(found_ientry != ientry)) { | |
389 | /* We found an entry in the idr with the right wd, but it's | |
390 | * not the entry we were told to remove. eparis seriously | |
391 | * fucked up somewhere. */ | |
392 | WARN_ON(1); | |
393 | ientry->wd = -1; | |
394 | goto out; | |
395 | } | |
396 | ||
397 | /* One ref for being in the idr, one ref held by the caller */ | |
398 | BUG_ON(atomic_read(&entry->refcnt) < 2); | |
399 | ||
400 | idr_remove(idr, wd); | |
7e790dd5 | 401 | ientry->wd = -1; |
dead537d EP |
402 | |
403 | /* removed from the idr, drop that ref */ | |
404 | fsnotify_put_mark(entry); | |
405 | out: | |
406 | spin_unlock(&group->inotify_data.idr_lock); | |
7e790dd5 | 407 | } |
dead537d | 408 | |
63c882a0 | 409 | /* |
dead537d | 410 | * Send IN_IGNORED for this wd, remove this wd from the idr. |
63c882a0 | 411 | */ |
528da3e9 EP |
412 | void inotify_ignored_and_remove_idr(struct fsnotify_mark_entry *entry, |
413 | struct fsnotify_group *group) | |
63c882a0 EP |
414 | { |
415 | struct inotify_inode_mark_entry *ientry; | |
f44aebcc | 416 | struct fsnotify_event *ignored_event; |
63c882a0 EP |
417 | struct inotify_event_private_data *event_priv; |
418 | struct fsnotify_event_private_data *fsn_event_priv; | |
eef3a116 | 419 | int ret; |
63c882a0 | 420 | |
f44aebcc EP |
421 | ignored_event = fsnotify_create_event(NULL, FS_IN_IGNORED, NULL, |
422 | FSNOTIFY_EVENT_NONE, NULL, 0, | |
423 | GFP_NOFS); | |
424 | if (!ignored_event) | |
425 | return; | |
426 | ||
63c882a0 EP |
427 | ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry); |
428 | ||
f44aebcc | 429 | event_priv = kmem_cache_alloc(event_priv_cachep, GFP_NOFS); |
63c882a0 EP |
430 | if (unlikely(!event_priv)) |
431 | goto skip_send_ignore; | |
432 | ||
433 | fsn_event_priv = &event_priv->fsnotify_event_priv_data; | |
434 | ||
435 | fsn_event_priv->group = group; | |
436 | event_priv->wd = ientry->wd; | |
437 | ||
eef3a116 EP |
438 | ret = fsnotify_add_notify_event(group, ignored_event, fsn_event_priv); |
439 | if (ret) | |
63c882a0 EP |
440 | inotify_free_event_priv(fsn_event_priv); |
441 | ||
442 | skip_send_ignore: | |
443 | ||
f44aebcc EP |
444 | /* matches the reference taken when the event was created */ |
445 | fsnotify_put_event(ignored_event); | |
446 | ||
63c882a0 | 447 | /* remove this entry from the idr */ |
7e790dd5 | 448 | inotify_remove_from_idr(group, ientry); |
63c882a0 | 449 | |
5549f7cd | 450 | atomic_dec(&group->inotify_data.user->inotify_watches); |
63c882a0 EP |
451 | } |
452 | ||
453 | /* ding dong the mark is dead */ | |
454 | static void inotify_free_mark(struct fsnotify_mark_entry *entry) | |
455 | { | |
456 | struct inotify_inode_mark_entry *ientry = (struct inotify_inode_mark_entry *)entry; | |
457 | ||
458 | kmem_cache_free(inotify_inode_mark_cachep, ientry); | |
459 | } | |
460 | ||
52cef755 EP |
461 | static int inotify_update_existing_watch(struct fsnotify_group *group, |
462 | struct inode *inode, | |
463 | u32 arg) | |
63c882a0 | 464 | { |
52cef755 | 465 | struct fsnotify_mark_entry *entry; |
63c882a0 | 466 | struct inotify_inode_mark_entry *ientry; |
63c882a0 | 467 | __u32 old_mask, new_mask; |
52cef755 EP |
468 | __u32 mask; |
469 | int add = (arg & IN_MASK_ADD); | |
470 | int ret; | |
63c882a0 EP |
471 | |
472 | /* don't allow invalid bits: we don't want flags set */ | |
473 | mask = inotify_arg_to_mask(arg); | |
474 | if (unlikely(!mask)) | |
475 | return -EINVAL; | |
476 | ||
63c882a0 EP |
477 | spin_lock(&inode->i_lock); |
478 | entry = fsnotify_find_mark_entry(group, inode); | |
479 | spin_unlock(&inode->i_lock); | |
52cef755 EP |
480 | if (!entry) |
481 | return -ENOENT; | |
7e790dd5 | 482 | |
52cef755 | 483 | ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry); |
75fe2b26 | 484 | |
63c882a0 EP |
485 | spin_lock(&entry->lock); |
486 | ||
487 | old_mask = entry->mask; | |
488 | if (add) { | |
489 | entry->mask |= mask; | |
490 | new_mask = entry->mask; | |
491 | } else { | |
492 | entry->mask = mask; | |
493 | new_mask = entry->mask; | |
494 | } | |
495 | ||
496 | spin_unlock(&entry->lock); | |
497 | ||
498 | if (old_mask != new_mask) { | |
499 | /* more bits in old than in new? */ | |
500 | int dropped = (old_mask & ~new_mask); | |
501 | /* more bits in this entry than the inode's mask? */ | |
502 | int do_inode = (new_mask & ~inode->i_fsnotify_mask); | |
503 | /* more bits in this entry than the group? */ | |
504 | int do_group = (new_mask & ~group->mask); | |
505 | ||
506 | /* update the inode with this new entry */ | |
507 | if (dropped || do_inode) | |
508 | fsnotify_recalc_inode_mask(inode); | |
509 | ||
510 | /* update the group mask with the new mask */ | |
511 | if (dropped || do_group) | |
512 | fsnotify_recalc_group_mask(group); | |
513 | } | |
514 | ||
52cef755 EP |
515 | /* return the wd */ |
516 | ret = ientry->wd; | |
517 | ||
518 | /* match the get from fsnotify_find_mark_entry() */ | |
75fe2b26 EP |
519 | fsnotify_put_mark(entry); |
520 | ||
52cef755 EP |
521 | return ret; |
522 | } | |
523 | ||
524 | static int inotify_new_watch(struct fsnotify_group *group, | |
525 | struct inode *inode, | |
526 | u32 arg) | |
527 | { | |
528 | struct inotify_inode_mark_entry *tmp_ientry; | |
529 | __u32 mask; | |
530 | int ret; | |
531 | ||
532 | /* don't allow invalid bits: we don't want flags set */ | |
533 | mask = inotify_arg_to_mask(arg); | |
534 | if (unlikely(!mask)) | |
535 | return -EINVAL; | |
536 | ||
537 | tmp_ientry = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL); | |
538 | if (unlikely(!tmp_ientry)) | |
539 | return -ENOMEM; | |
540 | ||
541 | fsnotify_init_mark(&tmp_ientry->fsn_entry, inotify_free_mark); | |
542 | tmp_ientry->fsn_entry.mask = mask; | |
543 | tmp_ientry->wd = -1; | |
544 | ||
545 | ret = -ENOSPC; | |
546 | if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches) | |
547 | goto out_err; | |
548 | retry: | |
549 | ret = -ENOMEM; | |
550 | if (unlikely(!idr_pre_get(&group->inotify_data.idr, GFP_KERNEL))) | |
551 | goto out_err; | |
552 | ||
553 | spin_lock(&group->inotify_data.idr_lock); | |
554 | ret = idr_get_new_above(&group->inotify_data.idr, &tmp_ientry->fsn_entry, | |
555 | group->inotify_data.last_wd, | |
556 | &tmp_ientry->wd); | |
557 | spin_unlock(&group->inotify_data.idr_lock); | |
558 | if (ret) { | |
559 | /* idr was out of memory allocate and try again */ | |
560 | if (ret == -EAGAIN) | |
561 | goto retry; | |
562 | goto out_err; | |
563 | } | |
564 | ||
dead537d EP |
565 | /* we put the mark on the idr, take a reference */ |
566 | fsnotify_get_mark(&tmp_ientry->fsn_entry); | |
567 | ||
52cef755 EP |
568 | /* we are on the idr, now get on the inode */ |
569 | ret = fsnotify_add_mark(&tmp_ientry->fsn_entry, group, inode); | |
570 | if (ret) { | |
571 | /* we failed to get on the inode, get off the idr */ | |
572 | inotify_remove_from_idr(group, tmp_ientry); | |
573 | goto out_err; | |
574 | } | |
575 | ||
52cef755 EP |
576 | /* update the idr hint, who cares about races, it's just a hint */ |
577 | group->inotify_data.last_wd = tmp_ientry->wd; | |
578 | ||
579 | /* increment the number of watches the user has */ | |
580 | atomic_inc(&group->inotify_data.user->inotify_watches); | |
581 | ||
582 | /* return the watch descriptor for this new entry */ | |
583 | ret = tmp_ientry->wd; | |
584 | ||
585 | /* match the ref from fsnotify_init_markentry() */ | |
586 | fsnotify_put_mark(&tmp_ientry->fsn_entry); | |
587 | ||
750a8870 EP |
588 | /* if this mark added a new event update the group mask */ |
589 | if (mask & ~group->mask) | |
590 | fsnotify_recalc_group_mask(group); | |
591 | ||
63c882a0 | 592 | out_err: |
52cef755 | 593 | if (ret < 0) |
7e790dd5 | 594 | kmem_cache_free(inotify_inode_mark_cachep, tmp_ientry); |
52cef755 EP |
595 | |
596 | return ret; | |
597 | } | |
598 | ||
599 | static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg) | |
600 | { | |
601 | int ret = 0; | |
602 | ||
603 | retry: | |
604 | /* try to update and existing watch with the new arg */ | |
605 | ret = inotify_update_existing_watch(group, inode, arg); | |
606 | /* no mark present, try to add a new one */ | |
607 | if (ret == -ENOENT) | |
608 | ret = inotify_new_watch(group, inode, arg); | |
609 | /* | |
610 | * inotify_new_watch could race with another thread which did an | |
611 | * inotify_new_watch between the update_existing and the add watch | |
612 | * here, go back and try to update an existing mark again. | |
613 | */ | |
614 | if (ret == -EEXIST) | |
615 | goto retry; | |
7e790dd5 | 616 | |
63c882a0 EP |
617 | return ret; |
618 | } | |
619 | ||
620 | static struct fsnotify_group *inotify_new_group(struct user_struct *user, unsigned int max_events) | |
621 | { | |
622 | struct fsnotify_group *group; | |
623 | unsigned int grp_num; | |
624 | ||
625 | /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */ | |
626 | grp_num = (INOTIFY_GROUP_NUM - atomic_inc_return(&inotify_grp_num)); | |
627 | group = fsnotify_obtain_group(grp_num, 0, &inotify_fsnotify_ops); | |
628 | if (IS_ERR(group)) | |
629 | return group; | |
630 | ||
631 | group->max_events = max_events; | |
632 | ||
633 | spin_lock_init(&group->inotify_data.idr_lock); | |
634 | idr_init(&group->inotify_data.idr); | |
08e53fcb | 635 | group->inotify_data.last_wd = 1; |
63c882a0 EP |
636 | group->inotify_data.user = user; |
637 | group->inotify_data.fa = NULL; | |
638 | ||
639 | return group; | |
640 | } | |
641 | ||
642 | ||
643 | /* inotify syscalls */ | |
938bb9f5 | 644 | SYSCALL_DEFINE1(inotify_init1, int, flags) |
2d9048e2 | 645 | { |
63c882a0 | 646 | struct fsnotify_group *group; |
2d9048e2 AG |
647 | struct user_struct *user; |
648 | struct file *filp; | |
649 | int fd, ret; | |
650 | ||
e38b36f3 UD |
651 | /* Check the IN_* constants for consistency. */ |
652 | BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC); | |
653 | BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK); | |
654 | ||
510df2dd | 655 | if (flags & ~(IN_CLOEXEC | IN_NONBLOCK)) |
4006553b UD |
656 | return -EINVAL; |
657 | ||
658 | fd = get_unused_fd_flags(flags & O_CLOEXEC); | |
2d9048e2 AG |
659 | if (fd < 0) |
660 | return fd; | |
661 | ||
662 | filp = get_empty_filp(); | |
663 | if (!filp) { | |
664 | ret = -ENFILE; | |
665 | goto out_put_fd; | |
666 | } | |
667 | ||
da9592ed | 668 | user = get_current_user(); |
2d9048e2 AG |
669 | if (unlikely(atomic_read(&user->inotify_devs) >= |
670 | inotify_max_user_instances)) { | |
671 | ret = -EMFILE; | |
672 | goto out_free_uid; | |
673 | } | |
674 | ||
63c882a0 EP |
675 | /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */ |
676 | group = inotify_new_group(user, inotify_max_queued_events); | |
677 | if (IS_ERR(group)) { | |
678 | ret = PTR_ERR(group); | |
2d9048e2 AG |
679 | goto out_free_uid; |
680 | } | |
681 | ||
2d9048e2 | 682 | filp->f_op = &inotify_fops; |
0f7fc9e4 JJS |
683 | filp->f_path.mnt = mntget(inotify_mnt); |
684 | filp->f_path.dentry = dget(inotify_mnt->mnt_root); | |
685 | filp->f_mapping = filp->f_path.dentry->d_inode->i_mapping; | |
2d9048e2 | 686 | filp->f_mode = FMODE_READ; |
510df2dd | 687 | filp->f_flags = O_RDONLY | (flags & O_NONBLOCK); |
63c882a0 EP |
688 | filp->private_data = group; |
689 | ||
2d9048e2 | 690 | atomic_inc(&user->inotify_devs); |
63c882a0 | 691 | |
2d9048e2 AG |
692 | fd_install(fd, filp); |
693 | ||
694 | return fd; | |
63c882a0 | 695 | |
2d9048e2 AG |
696 | out_free_uid: |
697 | free_uid(user); | |
698 | put_filp(filp); | |
699 | out_put_fd: | |
700 | put_unused_fd(fd); | |
701 | return ret; | |
702 | } | |
703 | ||
938bb9f5 | 704 | SYSCALL_DEFINE0(inotify_init) |
4006553b UD |
705 | { |
706 | return sys_inotify_init1(0); | |
707 | } | |
708 | ||
2e4d0924 HC |
709 | SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname, |
710 | u32, mask) | |
2d9048e2 | 711 | { |
63c882a0 | 712 | struct fsnotify_group *group; |
2d9048e2 | 713 | struct inode *inode; |
2d8f3038 | 714 | struct path path; |
2d9048e2 AG |
715 | struct file *filp; |
716 | int ret, fput_needed; | |
717 | unsigned flags = 0; | |
718 | ||
719 | filp = fget_light(fd, &fput_needed); | |
720 | if (unlikely(!filp)) | |
721 | return -EBADF; | |
722 | ||
723 | /* verify that this is indeed an inotify instance */ | |
724 | if (unlikely(filp->f_op != &inotify_fops)) { | |
725 | ret = -EINVAL; | |
726 | goto fput_and_out; | |
727 | } | |
728 | ||
729 | if (!(mask & IN_DONT_FOLLOW)) | |
730 | flags |= LOOKUP_FOLLOW; | |
731 | if (mask & IN_ONLYDIR) | |
732 | flags |= LOOKUP_DIRECTORY; | |
733 | ||
63c882a0 EP |
734 | ret = inotify_find_inode(pathname, &path, flags); |
735 | if (ret) | |
2d9048e2 AG |
736 | goto fput_and_out; |
737 | ||
63c882a0 | 738 | /* inode held in place by reference to path; group by fget on fd */ |
2d8f3038 | 739 | inode = path.dentry->d_inode; |
63c882a0 | 740 | group = filp->private_data; |
2d9048e2 | 741 | |
63c882a0 EP |
742 | /* create/update an inode mark */ |
743 | ret = inotify_update_watch(group, inode, mask); | |
744 | if (unlikely(ret)) | |
745 | goto path_put_and_out; | |
2d9048e2 | 746 | |
63c882a0 | 747 | path_put_and_out: |
2d8f3038 | 748 | path_put(&path); |
2d9048e2 AG |
749 | fput_and_out: |
750 | fput_light(filp, fput_needed); | |
751 | return ret; | |
752 | } | |
753 | ||
2e4d0924 | 754 | SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd) |
2d9048e2 | 755 | { |
63c882a0 EP |
756 | struct fsnotify_group *group; |
757 | struct fsnotify_mark_entry *entry; | |
2d9048e2 | 758 | struct file *filp; |
63c882a0 | 759 | int ret = 0, fput_needed; |
2d9048e2 AG |
760 | |
761 | filp = fget_light(fd, &fput_needed); | |
762 | if (unlikely(!filp)) | |
763 | return -EBADF; | |
764 | ||
765 | /* verify that this is indeed an inotify instance */ | |
766 | if (unlikely(filp->f_op != &inotify_fops)) { | |
767 | ret = -EINVAL; | |
768 | goto out; | |
769 | } | |
770 | ||
63c882a0 | 771 | group = filp->private_data; |
2d9048e2 | 772 | |
63c882a0 EP |
773 | spin_lock(&group->inotify_data.idr_lock); |
774 | entry = idr_find(&group->inotify_data.idr, wd); | |
775 | if (unlikely(!entry)) { | |
776 | spin_unlock(&group->inotify_data.idr_lock); | |
777 | ret = -EINVAL; | |
778 | goto out; | |
779 | } | |
780 | fsnotify_get_mark(entry); | |
781 | spin_unlock(&group->inotify_data.idr_lock); | |
782 | ||
528da3e9 | 783 | fsnotify_destroy_mark_by_entry(entry); |
63c882a0 | 784 | fsnotify_put_mark(entry); |
2d9048e2 AG |
785 | |
786 | out: | |
787 | fput_light(filp, fput_needed); | |
788 | return ret; | |
789 | } | |
790 | ||
454e2398 | 791 | static int |
2d9048e2 | 792 | inotify_get_sb(struct file_system_type *fs_type, int flags, |
454e2398 | 793 | const char *dev_name, void *data, struct vfsmount *mnt) |
2d9048e2 | 794 | { |
fd5eea42 AM |
795 | return get_sb_pseudo(fs_type, "inotify", NULL, |
796 | INOTIFYFS_SUPER_MAGIC, mnt); | |
2d9048e2 AG |
797 | } |
798 | ||
799 | static struct file_system_type inotify_fs_type = { | |
63c882a0 EP |
800 | .name = "inotifyfs", |
801 | .get_sb = inotify_get_sb, | |
802 | .kill_sb = kill_anon_super, | |
2d9048e2 AG |
803 | }; |
804 | ||
805 | /* | |
806 | * inotify_user_setup - Our initialization function. Note that we cannnot return | |
807 | * error because we have compiled-in VFS hooks. So an (unlikely) failure here | |
808 | * must result in panic(). | |
809 | */ | |
810 | static int __init inotify_user_setup(void) | |
811 | { | |
812 | int ret; | |
813 | ||
814 | ret = register_filesystem(&inotify_fs_type); | |
815 | if (unlikely(ret)) | |
816 | panic("inotify: register_filesystem returned %d!\n", ret); | |
817 | ||
818 | inotify_mnt = kern_mount(&inotify_fs_type); | |
819 | if (IS_ERR(inotify_mnt)) | |
820 | panic("inotify: kern_mount ret %ld!\n", PTR_ERR(inotify_mnt)); | |
821 | ||
63c882a0 EP |
822 | inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark_entry, SLAB_PANIC); |
823 | event_priv_cachep = KMEM_CACHE(inotify_event_private_data, SLAB_PANIC); | |
63c882a0 | 824 | |
2d9048e2 AG |
825 | inotify_max_queued_events = 16384; |
826 | inotify_max_user_instances = 128; | |
827 | inotify_max_user_watches = 8192; | |
828 | ||
2d9048e2 AG |
829 | return 0; |
830 | } | |
2d9048e2 | 831 | module_init(inotify_user_setup); |