1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_FS_NOTIFY_H
3#define _LINUX_FS_NOTIFY_H
4
5/*
6 * include/linux/fsnotify.h - generic hooks for filesystem notification, to
7 * reduce in-source duplication from both dnotify and inotify.
8 *
9 * We don't compile any of this away in some complicated menagerie of ifdefs.
10 * Instead, we rely on the code inside to optimize away as needed.
11 *
12 * (C) Copyright 2005 Robert Love
13 */
14
15#include <linux/fsnotify_backend.h>
16#include <linux/audit.h>
17#include <linux/slab.h>
18#include <linux/bug.h>
19
20/* Are there any inode/mount/sb objects watched with priority prio or above? */
21static inline bool fsnotify_sb_has_priority_watchers(struct super_block *sb,
22 int prio)
23{
24 struct fsnotify_sb_info *sbinfo = fsnotify_sb_info(sb);
25
26 /* Were any marks ever added to any object on this sb? */
27 if (!sbinfo)
28 return false;
29
30 return atomic_long_read(v: &sbinfo->watched_objects[prio]);
31}
32
33/* Are there any inode/mount/sb objects that are being watched at all? */
34static inline bool fsnotify_sb_has_watchers(struct super_block *sb)
35{
36 return fsnotify_sb_has_priority_watchers(sb, prio: 0);
37}
38
39/*
40 * Notify this @dir inode about a change in a child directory entry.
41 * The directory entry may have turned positive or negative or its inode may
42 * have changed (i.e. renamed over).
43 *
44 * Unlike fsnotify_parent(), the event will be reported regardless of the
45 * FS_EVENT_ON_CHILD mask on the parent inode and will not be reported if only
46 * the child is interested and not the parent.
47 */
48static inline int fsnotify_name(__u32 mask, const void *data, int data_type,
49 struct inode *dir, const struct qstr *name,
50 u32 cookie)
51{
52 if (!fsnotify_sb_has_watchers(sb: dir->i_sb))
53 return 0;
54
55 return fsnotify(mask, data, data_type, dir, name, NULL, cookie);
56}
57
58static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry,
59 __u32 mask)
60{
61 fsnotify_name(mask, data: dentry, data_type: FSNOTIFY_EVENT_DENTRY, dir, name: &dentry->d_name, cookie: 0);
62}
63
64static inline void fsnotify_inode(struct inode *inode, __u32 mask)
65{
66 if (!fsnotify_sb_has_watchers(sb: inode->i_sb))
67 return;
68
69 if (S_ISDIR(inode->i_mode))
70 mask |= FS_ISDIR;
71
72 fsnotify(mask, data: inode, data_type: FSNOTIFY_EVENT_INODE, NULL, NULL, inode, cookie: 0);
73}
74
75/* Notify this dentry's parent about a child's events. */
76static inline int fsnotify_parent(struct dentry *dentry, __u32 mask,
77 const void *data, int data_type)
78{
79 struct inode *inode = d_inode(dentry);
80
81 if (!fsnotify_sb_has_watchers(sb: inode->i_sb))
82 return 0;
83
84 if (S_ISDIR(inode->i_mode)) {
85 mask |= FS_ISDIR;
86
87 /* sb/mount marks are not interested in name of directory */
88 if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
89 goto notify_child;
90 }
91
92 /* disconnected dentry cannot notify parent */
93 if (IS_ROOT(dentry))
94 goto notify_child;
95
96 return __fsnotify_parent(dentry, mask, data, data_type);
97
98notify_child:
99 return fsnotify(mask, data, data_type, NULL, NULL, inode, cookie: 0);
100}
101
102/*
103 * Simple wrappers to consolidate calls to fsnotify_parent() when an event
104 * is on a file/dentry.
105 */
106static inline void fsnotify_dentry(struct dentry *dentry, __u32 mask)
107{
108 fsnotify_parent(dentry, mask, data: dentry, data_type: FSNOTIFY_EVENT_DENTRY);
109}
110
111static inline int fsnotify_path(const struct path *path, __u32 mask)
112{
113 return fsnotify_parent(dentry: path->dentry, mask, data: path, data_type: FSNOTIFY_EVENT_PATH);
114}
115
116static inline int fsnotify_file(struct file *file, __u32 mask)
117{
118 /*
119 * FMODE_NONOTIFY are fds generated by fanotify itself which should not
120 * generate new events. We also don't want to generate events for
121 * FMODE_PATH fds (involves open & close events) as they are just
122 * handle creation / destruction events and not "real" file events.
123 */
124 if (FMODE_FSNOTIFY_NONE(file->f_mode))
125 return 0;
126
127 return fsnotify_path(path: &file->f_path, mask);
128}
129
130#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
131
132int fsnotify_open_perm_and_set_mode(struct file *file);
133
134/*
135 * fsnotify_file_area_perm - permission hook before access to file range
136 */
137static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
138 const loff_t *ppos, size_t count)
139{
140 /*
141 * filesystem may be modified in the context of permission events
142 * (e.g. by HSM filling a file on access), so sb freeze protection
143 * must not be held.
144 */
145 lockdep_assert_once(file_write_not_started(file));
146
147 if (!(perm_mask & (MAY_READ | MAY_WRITE | MAY_ACCESS)))
148 return 0;
149
150 /*
151 * read()/write() and other types of access generate pre-content events.
152 */
153 if (unlikely(FMODE_FSNOTIFY_HSM(file->f_mode))) {
154 int ret = fsnotify_pre_content(&file->f_path, ppos, count);
155
156 if (ret)
157 return ret;
158 }
159
160 if (!(perm_mask & MAY_READ) ||
161 likely(!FMODE_FSNOTIFY_ACCESS_PERM(file->f_mode)))
162 return 0;
163
164 /*
165 * read() also generates the legacy FS_ACCESS_PERM event, so content
166 * scanners can inspect the content filled by pre-content event.
167 */
168 return fsnotify_path(&file->f_path, FS_ACCESS_PERM);
169}
170
171/*
172 * fsnotify_mmap_perm - permission hook before mmap of file range
173 */
174static inline int fsnotify_mmap_perm(struct file *file, int prot,
175 const loff_t off, size_t len)
176{
177 /*
178 * mmap() generates only pre-content events.
179 */
180 if (!file || likely(!FMODE_FSNOTIFY_HSM(file->f_mode)))
181 return 0;
182
183 return fsnotify_pre_content(&file->f_path, &off, len);
184}
185
186/*
187 * fsnotify_truncate_perm - permission hook before file truncate
188 */
189static inline int fsnotify_truncate_perm(const struct path *path, loff_t length)
190{
191 struct inode *inode = d_inode(path->dentry);
192
193 if (!(inode->i_sb->s_iflags & SB_I_ALLOW_HSM) ||
194 !fsnotify_sb_has_priority_watchers(inode->i_sb,
195 FSNOTIFY_PRIO_PRE_CONTENT))
196 return 0;
197
198 return fsnotify_pre_content(path, &length, 0);
199}
200
201/*
202 * fsnotify_file_perm - permission hook before file access (unknown range)
203 */
204static inline int fsnotify_file_perm(struct file *file, int perm_mask)
205{
206 return fsnotify_file_area_perm(file, perm_mask, NULL, 0);
207}
208
209#else
210static inline int fsnotify_open_perm_and_set_mode(struct file *file)
211{
212 return 0;
213}
214
215static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
216 const loff_t *ppos, size_t count)
217{
218 return 0;
219}
220
221static inline int fsnotify_mmap_perm(struct file *file, int prot,
222 const loff_t off, size_t len)
223{
224 return 0;
225}
226
227static inline int fsnotify_truncate_perm(const struct path *path, loff_t length)
228{
229 return 0;
230}
231
232static inline int fsnotify_file_perm(struct file *file, int perm_mask)
233{
234 return 0;
235}
236#endif
237
238/*
239 * fsnotify_link_count - inode's link count changed
240 */
241static inline void fsnotify_link_count(struct inode *inode)
242{
243 fsnotify_inode(inode, FS_ATTRIB);
244}
245
246/*
247 * fsnotify_move - file old_name at old_dir was moved to new_name at new_dir
248 */
249static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
250 const struct qstr *old_name,
251 int isdir, struct inode *target,
252 struct dentry *moved)
253{
254 struct inode *source = moved->d_inode;
255 u32 fs_cookie = fsnotify_get_cookie();
256 __u32 old_dir_mask = FS_MOVED_FROM;
257 __u32 new_dir_mask = FS_MOVED_TO;
258 __u32 rename_mask = FS_RENAME;
259 const struct qstr *new_name = &moved->d_name;
260
261 if (isdir) {
262 old_dir_mask |= FS_ISDIR;
263 new_dir_mask |= FS_ISDIR;
264 rename_mask |= FS_ISDIR;
265 }
266
267 /* Event with information about both old and new parent+name */
268 fsnotify_name(mask: rename_mask, data: moved, data_type: FSNOTIFY_EVENT_DENTRY,
269 dir: old_dir, name: old_name, cookie: 0);
270
271 fsnotify_name(mask: old_dir_mask, data: source, data_type: FSNOTIFY_EVENT_INODE,
272 dir: old_dir, name: old_name, cookie: fs_cookie);
273 fsnotify_name(mask: new_dir_mask, data: source, data_type: FSNOTIFY_EVENT_INODE,
274 dir: new_dir, name: new_name, cookie: fs_cookie);
275
276 if (target)
277 fsnotify_link_count(inode: target);
278 fsnotify_inode(inode: source, FS_MOVE_SELF);
279 audit_inode_child(parent: new_dir, dentry: moved, AUDIT_TYPE_CHILD_CREATE);
280}
281
282/*
283 * fsnotify_inode_delete - and inode is being evicted from cache, clean up is needed
284 */
285static inline void fsnotify_inode_delete(struct inode *inode)
286{
287 __fsnotify_inode_delete(inode);
288}
289
290/*
291 * fsnotify_vfsmount_delete - a vfsmount is being destroyed, clean up is needed
292 */
293static inline void fsnotify_vfsmount_delete(struct vfsmount *mnt)
294{
295 __fsnotify_vfsmount_delete(mnt);
296}
297
298static inline void fsnotify_mntns_delete(struct mnt_namespace *mntns)
299{
300 __fsnotify_mntns_delete(mntns);
301}
302
303/*
304 * fsnotify_inoderemove - an inode is going away
305 */
306static inline void fsnotify_inoderemove(struct inode *inode)
307{
308 fsnotify_inode(inode, FS_DELETE_SELF);
309 __fsnotify_inode_delete(inode);
310}
311
312/*
313 * fsnotify_create - 'name' was linked in
314 *
315 * Caller must make sure that dentry->d_name is stable.
316 * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
317 * ->d_inode later
318 */
319static inline void fsnotify_create(struct inode *dir, struct dentry *dentry)
320{
321 audit_inode_child(parent: dir, dentry, AUDIT_TYPE_CHILD_CREATE);
322
323 fsnotify_dirent(dir, dentry, FS_CREATE);
324}
325
326/*
327 * fsnotify_link - new hardlink in 'inode' directory
328 *
329 * Caller must make sure that new_dentry->d_name is stable.
330 * Note: We have to pass also the linked inode ptr as some filesystems leave
331 * new_dentry->d_inode NULL and instantiate inode pointer later
332 */
333static inline void fsnotify_link(struct inode *dir, struct inode *inode,
334 struct dentry *new_dentry)
335{
336 fsnotify_link_count(inode);
337 audit_inode_child(parent: dir, dentry: new_dentry, AUDIT_TYPE_CHILD_CREATE);
338
339 fsnotify_name(FS_CREATE, data: inode, data_type: FSNOTIFY_EVENT_INODE,
340 dir, name: &new_dentry->d_name, cookie: 0);
341}
342
343/*
344 * fsnotify_delete - @dentry was unlinked and unhashed
345 *
346 * Caller must make sure that dentry->d_name is stable.
347 *
348 * Note: unlike fsnotify_unlink(), we have to pass also the unlinked inode
349 * as this may be called after d_delete() and old_dentry may be negative.
350 */
351static inline void fsnotify_delete(struct inode *dir, struct inode *inode,
352 struct dentry *dentry)
353{
354 __u32 mask = FS_DELETE;
355
356 if (S_ISDIR(inode->i_mode))
357 mask |= FS_ISDIR;
358
359 fsnotify_name(mask, data: inode, data_type: FSNOTIFY_EVENT_INODE, dir, name: &dentry->d_name,
360 cookie: 0);
361}
362
363/**
364 * d_delete_notify - delete a dentry and call fsnotify_delete()
365 * @dentry: The dentry to delete
366 *
367 * This helper is used to guaranty that the unlinked inode cannot be found
368 * by lookup of this name after fsnotify_delete() event has been delivered.
369 */
370static inline void d_delete_notify(struct inode *dir, struct dentry *dentry)
371{
372 struct inode *inode = d_inode(dentry);
373
374 ihold(inode);
375 d_delete(dentry);
376 fsnotify_delete(dir, inode, dentry);
377 iput(inode);
378}
379
380/*
381 * fsnotify_unlink - 'name' was unlinked
382 *
383 * Caller must make sure that dentry->d_name is stable.
384 */
385static inline void fsnotify_unlink(struct inode *dir, struct dentry *dentry)
386{
387 if (WARN_ON_ONCE(d_is_negative(dentry)))
388 return;
389
390 fsnotify_delete(dir, inode: d_inode(dentry), dentry);
391}
392
393/*
394 * fsnotify_mkdir - directory 'name' was created
395 *
396 * Caller must make sure that dentry->d_name is stable.
397 * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
398 * ->d_inode later
399 */
400static inline void fsnotify_mkdir(struct inode *dir, struct dentry *dentry)
401{
402 audit_inode_child(parent: dir, dentry, AUDIT_TYPE_CHILD_CREATE);
403
404 fsnotify_dirent(dir, dentry, FS_CREATE | FS_ISDIR);
405}
406
407/*
408 * fsnotify_rmdir - directory 'name' was removed
409 *
410 * Caller must make sure that dentry->d_name is stable.
411 */
412static inline void fsnotify_rmdir(struct inode *dir, struct dentry *dentry)
413{
414 if (WARN_ON_ONCE(d_is_negative(dentry)))
415 return;
416
417 fsnotify_delete(dir, inode: d_inode(dentry), dentry);
418}
419
420/*
421 * fsnotify_access - file was read
422 */
423static inline void fsnotify_access(struct file *file)
424{
425 fsnotify_file(file, FS_ACCESS);
426}
427
428/*
429 * fsnotify_modify - file was modified
430 */
431static inline void fsnotify_modify(struct file *file)
432{
433 fsnotify_file(file, FS_MODIFY);
434}
435
436/*
437 * fsnotify_open - file was opened
438 */
439static inline void fsnotify_open(struct file *file)
440{
441 __u32 mask = FS_OPEN;
442
443 if (file->f_flags & __FMODE_EXEC)
444 mask |= FS_OPEN_EXEC;
445
446 fsnotify_file(file, mask);
447}
448
449/*
450 * fsnotify_close - file was closed
451 */
452static inline void fsnotify_close(struct file *file)
453{
454 __u32 mask = (file->f_mode & FMODE_WRITE) ? FS_CLOSE_WRITE :
455 FS_CLOSE_NOWRITE;
456
457 fsnotify_file(file, mask);
458}
459
460/*
461 * fsnotify_xattr - extended attributes were changed
462 */
463static inline void fsnotify_xattr(struct dentry *dentry)
464{
465 fsnotify_dentry(dentry, FS_ATTRIB);
466}
467
468/*
469 * fsnotify_change - notify_change event. file was modified and/or metadata
470 * was changed.
471 */
472static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
473{
474 __u32 mask = 0;
475
476 if (ia_valid & ATTR_UID)
477 mask |= FS_ATTRIB;
478 if (ia_valid & ATTR_GID)
479 mask |= FS_ATTRIB;
480 if (ia_valid & ATTR_SIZE)
481 mask |= FS_MODIFY;
482
483 /* both times implies a utime(s) call */
484 if ((ia_valid & (ATTR_ATIME | ATTR_MTIME)) == (ATTR_ATIME | ATTR_MTIME))
485 mask |= FS_ATTRIB;
486 else if (ia_valid & ATTR_ATIME)
487 mask |= FS_ACCESS;
488 else if (ia_valid & ATTR_MTIME)
489 mask |= FS_MODIFY;
490
491 if (ia_valid & ATTR_MODE)
492 mask |= FS_ATTRIB;
493
494 if (mask)
495 fsnotify_dentry(dentry, mask);
496}
497
498static inline int fsnotify_sb_error(struct super_block *sb, struct inode *inode,
499 int error)
500{
501 struct fs_error_report report = {
502 .error = error,
503 .inode = inode,
504 .sb = sb,
505 };
506
507 return fsnotify(FS_ERROR, data: &report, data_type: FSNOTIFY_EVENT_ERROR,
508 NULL, NULL, NULL, cookie: 0);
509}
510
511static inline void fsnotify_mnt_attach(struct mnt_namespace *ns, struct vfsmount *mnt)
512{
513 fsnotify_mnt(FS_MNT_ATTACH, ns, mnt);
514}
515
516static inline void fsnotify_mnt_detach(struct mnt_namespace *ns, struct vfsmount *mnt)
517{
518 fsnotify_mnt(FS_MNT_DETACH, ns, mnt);
519}
520
521static inline void fsnotify_mnt_move(struct mnt_namespace *ns, struct vfsmount *mnt)
522{
523 fsnotify_mnt(FS_MNT_MOVE, ns, mnt);
524}
525
526#endif /* _LINUX_FS_NOTIFY_H */
527