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 that are being watched at all? */
21static inline bool fsnotify_sb_has_watchers(struct super_block *sb)
22{
23	return atomic_long_read(&sb->s_fsnotify_connectors);
24}
25
26/*
27 * Notify this @dir inode about a change in a child directory entry.
28 * The directory entry may have turned positive or negative or its inode may
29 * have changed (i.e. renamed over).
30 *
31 * Unlike fsnotify_parent(), the event will be reported regardless of the
32 * FS_EVENT_ON_CHILD mask on the parent inode and will not be reported if only
33 * the child is interested and not the parent.
34 */
35static inline int fsnotify_name(__u32 mask, const void *data, int data_type,
36				struct inode *dir, const struct qstr *name,
37				u32 cookie)
38{
39	if (!fsnotify_sb_has_watchers(dir->i_sb))
40		return 0;
41
42	return fsnotify(mask, data, data_type, dir, name, NULL, cookie);
43}
44
45static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry,
46				   __u32 mask)
47{
48	fsnotify_name(mask, dentry, FSNOTIFY_EVENT_DENTRY, dir, &dentry->d_name, 0);
49}
50
51static inline void fsnotify_inode(struct inode *inode, __u32 mask)
52{
53	if (!fsnotify_sb_has_watchers(inode->i_sb))
54		return;
55
56	if (S_ISDIR(inode->i_mode))
57		mask |= FS_ISDIR;
58
59	fsnotify(mask, inode, FSNOTIFY_EVENT_INODE, NULL, NULL, inode, 0);
60}
61
62/* Notify this dentry's parent about a child's events. */
63static inline int fsnotify_parent(struct dentry *dentry, __u32 mask,
64				  const void *data, int data_type)
65{
66	struct inode *inode = d_inode(dentry);
67
68	if (!fsnotify_sb_has_watchers(inode->i_sb))
69		return 0;
70
71	if (S_ISDIR(inode->i_mode)) {
72		mask |= FS_ISDIR;
73
74		/* sb/mount marks are not interested in name of directory */
75		if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
76			goto notify_child;
77	}
78
79	/* disconnected dentry cannot notify parent */
80	if (IS_ROOT(dentry))
81		goto notify_child;
82
83	return __fsnotify_parent(dentry, mask, data, data_type);
84
85notify_child:
86	return fsnotify(mask, data, data_type, NULL, NULL, inode, 0);
87}
88
89/*
90 * Simple wrappers to consolidate calls to fsnotify_parent() when an event
91 * is on a file/dentry.
92 */
93static inline void fsnotify_dentry(struct dentry *dentry, __u32 mask)
94{
95	fsnotify_parent(dentry, mask, dentry, FSNOTIFY_EVENT_DENTRY);
96}
97
98static inline int fsnotify_file(struct file *file, __u32 mask)
99{
100	const struct path *path;
101
102	if (file->f_mode & FMODE_NONOTIFY)
103		return 0;
104
105	path = &file->f_path;
106	return fsnotify_parent(path->dentry, mask, path, FSNOTIFY_EVENT_PATH);
107}
108
109#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
110/*
111 * fsnotify_file_area_perm - permission hook before access to file range
112 */
113static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
114					  const loff_t *ppos, size_t count)
115{
116	__u32 fsnotify_mask = FS_ACCESS_PERM;
117
118	/*
119	 * filesystem may be modified in the context of permission events
120	 * (e.g. by HSM filling a file on access), so sb freeze protection
121	 * must not be held.
122	 */
123	lockdep_assert_once(file_write_not_started(file));
124
125	if (!(perm_mask & MAY_READ))
126		return 0;
127
128	return fsnotify_file(file, fsnotify_mask);
129}
130
131/*
132 * fsnotify_file_perm - permission hook before file access
133 */
134static inline int fsnotify_file_perm(struct file *file, int perm_mask)
135{
136	return fsnotify_file_area_perm(file, perm_mask, NULL, 0);
137}
138
139/*
140 * fsnotify_open_perm - permission hook before file open
141 */
142static inline int fsnotify_open_perm(struct file *file)
143{
144	int ret;
145
146	if (file->f_flags & __FMODE_EXEC) {
147		ret = fsnotify_file(file, FS_OPEN_EXEC_PERM);
148		if (ret)
149			return ret;
150	}
151
152	return fsnotify_file(file, FS_OPEN_PERM);
153}
154
155#else
156static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
157					  const loff_t *ppos, size_t count)
158{
159	return 0;
160}
161
162static inline int fsnotify_file_perm(struct file *file, int perm_mask)
163{
164	return 0;
165}
166
167static inline int fsnotify_open_perm(struct file *file)
168{
169	return 0;
170}
171#endif
172
173/*
174 * fsnotify_link_count - inode's link count changed
175 */
176static inline void fsnotify_link_count(struct inode *inode)
177{
178	fsnotify_inode(inode, FS_ATTRIB);
179}
180
181/*
182 * fsnotify_move - file old_name at old_dir was moved to new_name at new_dir
183 */
184static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
185				 const struct qstr *old_name,
186				 int isdir, struct inode *target,
187				 struct dentry *moved)
188{
189	struct inode *source = moved->d_inode;
190	u32 fs_cookie = fsnotify_get_cookie();
191	__u32 old_dir_mask = FS_MOVED_FROM;
192	__u32 new_dir_mask = FS_MOVED_TO;
193	__u32 rename_mask = FS_RENAME;
194	const struct qstr *new_name = &moved->d_name;
195
196	if (isdir) {
197		old_dir_mask |= FS_ISDIR;
198		new_dir_mask |= FS_ISDIR;
199		rename_mask |= FS_ISDIR;
200	}
201
202	/* Event with information about both old and new parent+name */
203	fsnotify_name(rename_mask, moved, FSNOTIFY_EVENT_DENTRY,
204		      old_dir, old_name, 0);
205
206	fsnotify_name(old_dir_mask, source, FSNOTIFY_EVENT_INODE,
207		      old_dir, old_name, fs_cookie);
208	fsnotify_name(new_dir_mask, source, FSNOTIFY_EVENT_INODE,
209		      new_dir, new_name, fs_cookie);
210
211	if (target)
212		fsnotify_link_count(target);
213	fsnotify_inode(source, FS_MOVE_SELF);
214	audit_inode_child(new_dir, moved, AUDIT_TYPE_CHILD_CREATE);
215}
216
217/*
218 * fsnotify_inode_delete - and inode is being evicted from cache, clean up is needed
219 */
220static inline void fsnotify_inode_delete(struct inode *inode)
221{
222	__fsnotify_inode_delete(inode);
223}
224
225/*
226 * fsnotify_vfsmount_delete - a vfsmount is being destroyed, clean up is needed
227 */
228static inline void fsnotify_vfsmount_delete(struct vfsmount *mnt)
229{
230	__fsnotify_vfsmount_delete(mnt);
231}
232
233/*
234 * fsnotify_inoderemove - an inode is going away
235 */
236static inline void fsnotify_inoderemove(struct inode *inode)
237{
238	fsnotify_inode(inode, FS_DELETE_SELF);
239	__fsnotify_inode_delete(inode);
240}
241
242/*
243 * fsnotify_create - 'name' was linked in
244 *
245 * Caller must make sure that dentry->d_name is stable.
246 * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
247 * ->d_inode later
248 */
249static inline void fsnotify_create(struct inode *dir, struct dentry *dentry)
250{
251	audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);
252
253	fsnotify_dirent(dir, dentry, FS_CREATE);
254}
255
256/*
257 * fsnotify_link - new hardlink in 'inode' directory
258 *
259 * Caller must make sure that new_dentry->d_name is stable.
260 * Note: We have to pass also the linked inode ptr as some filesystems leave
261 *   new_dentry->d_inode NULL and instantiate inode pointer later
262 */
263static inline void fsnotify_link(struct inode *dir, struct inode *inode,
264				 struct dentry *new_dentry)
265{
266	fsnotify_link_count(inode);
267	audit_inode_child(dir, new_dentry, AUDIT_TYPE_CHILD_CREATE);
268
269	fsnotify_name(FS_CREATE, inode, FSNOTIFY_EVENT_INODE,
270		      dir, &new_dentry->d_name, 0);
271}
272
273/*
274 * fsnotify_delete - @dentry was unlinked and unhashed
275 *
276 * Caller must make sure that dentry->d_name is stable.
277 *
278 * Note: unlike fsnotify_unlink(), we have to pass also the unlinked inode
279 * as this may be called after d_delete() and old_dentry may be negative.
280 */
281static inline void fsnotify_delete(struct inode *dir, struct inode *inode,
282				   struct dentry *dentry)
283{
284	__u32 mask = FS_DELETE;
285
286	if (S_ISDIR(inode->i_mode))
287		mask |= FS_ISDIR;
288
289	fsnotify_name(mask, inode, FSNOTIFY_EVENT_INODE, dir, &dentry->d_name,
290		      0);
291}
292
293/**
294 * d_delete_notify - delete a dentry and call fsnotify_delete()
295 * @dentry: The dentry to delete
296 *
297 * This helper is used to guaranty that the unlinked inode cannot be found
298 * by lookup of this name after fsnotify_delete() event has been delivered.
299 */
300static inline void d_delete_notify(struct inode *dir, struct dentry *dentry)
301{
302	struct inode *inode = d_inode(dentry);
303
304	ihold(inode);
305	d_delete(dentry);
306	fsnotify_delete(dir, inode, dentry);
307	iput(inode);
308}
309
310/*
311 * fsnotify_unlink - 'name' was unlinked
312 *
313 * Caller must make sure that dentry->d_name is stable.
314 */
315static inline void fsnotify_unlink(struct inode *dir, struct dentry *dentry)
316{
317	if (WARN_ON_ONCE(d_is_negative(dentry)))
318		return;
319
320	fsnotify_delete(dir, d_inode(dentry), dentry);
321}
322
323/*
324 * fsnotify_mkdir - directory 'name' was created
325 *
326 * Caller must make sure that dentry->d_name is stable.
327 * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
328 * ->d_inode later
329 */
330static inline void fsnotify_mkdir(struct inode *dir, struct dentry *dentry)
331{
332	audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);
333
334	fsnotify_dirent(dir, dentry, FS_CREATE | FS_ISDIR);
335}
336
337/*
338 * fsnotify_rmdir - directory 'name' was removed
339 *
340 * Caller must make sure that dentry->d_name is stable.
341 */
342static inline void fsnotify_rmdir(struct inode *dir, struct dentry *dentry)
343{
344	if (WARN_ON_ONCE(d_is_negative(dentry)))
345		return;
346
347	fsnotify_delete(dir, d_inode(dentry), dentry);
348}
349
350/*
351 * fsnotify_access - file was read
352 */
353static inline void fsnotify_access(struct file *file)
354{
355	fsnotify_file(file, FS_ACCESS);
356}
357
358/*
359 * fsnotify_modify - file was modified
360 */
361static inline void fsnotify_modify(struct file *file)
362{
363	fsnotify_file(file, FS_MODIFY);
364}
365
366/*
367 * fsnotify_open - file was opened
368 */
369static inline void fsnotify_open(struct file *file)
370{
371	__u32 mask = FS_OPEN;
372
373	if (file->f_flags & __FMODE_EXEC)
374		mask |= FS_OPEN_EXEC;
375
376	fsnotify_file(file, mask);
377}
378
379/*
380 * fsnotify_close - file was closed
381 */
382static inline void fsnotify_close(struct file *file)
383{
384	__u32 mask = (file->f_mode & FMODE_WRITE) ? FS_CLOSE_WRITE :
385						    FS_CLOSE_NOWRITE;
386
387	fsnotify_file(file, mask);
388}
389
390/*
391 * fsnotify_xattr - extended attributes were changed
392 */
393static inline void fsnotify_xattr(struct dentry *dentry)
394{
395	fsnotify_dentry(dentry, FS_ATTRIB);
396}
397
398/*
399 * fsnotify_change - notify_change event.  file was modified and/or metadata
400 * was changed.
401 */
402static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
403{
404	__u32 mask = 0;
405
406	if (ia_valid & ATTR_UID)
407		mask |= FS_ATTRIB;
408	if (ia_valid & ATTR_GID)
409		mask |= FS_ATTRIB;
410	if (ia_valid & ATTR_SIZE)
411		mask |= FS_MODIFY;
412
413	/* both times implies a utime(s) call */
414	if ((ia_valid & (ATTR_ATIME | ATTR_MTIME)) == (ATTR_ATIME | ATTR_MTIME))
415		mask |= FS_ATTRIB;
416	else if (ia_valid & ATTR_ATIME)
417		mask |= FS_ACCESS;
418	else if (ia_valid & ATTR_MTIME)
419		mask |= FS_MODIFY;
420
421	if (ia_valid & ATTR_MODE)
422		mask |= FS_ATTRIB;
423
424	if (mask)
425		fsnotify_dentry(dentry, mask);
426}
427
428static inline int fsnotify_sb_error(struct super_block *sb, struct inode *inode,
429				    int error)
430{
431	struct fs_error_report report = {
432		.error = error,
433		.inode = inode,
434		.sb = sb,
435	};
436
437	return fsnotify(FS_ERROR, &report, FSNOTIFY_EVENT_ERROR,
438			NULL, NULL, NULL, 0);
439}
440
441#endif	/* _LINUX_FS_NOTIFY_H */
442