xref: /linux/include/linux/fsnotify.h (revision f4915933947c71f08ed1c5a6c9b4fdbe735e18cf)
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? */
fsnotify_sb_has_priority_watchers(struct super_block * sb,int prio)21 static 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(&sbinfo->watched_objects[prio]);
31 }
32 
33 /* Are there any inode/mount/sb objects that are being watched at all? */
fsnotify_sb_has_watchers(struct super_block * sb)34 static inline bool fsnotify_sb_has_watchers(struct super_block *sb)
35 {
36 	return fsnotify_sb_has_priority_watchers(sb, 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  */
fsnotify_name(__u32 mask,const void * data,int data_type,struct inode * dir,const struct qstr * name,u32 cookie)48 static 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(dir->i_sb))
53 		return 0;
54 
55 	return fsnotify(mask, data, data_type, dir, name, NULL, cookie);
56 }
57 
fsnotify_dirent(struct inode * dir,struct dentry * dentry,__u32 mask)58 static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry,
59 				   __u32 mask)
60 {
61 	fsnotify_name(mask, dentry, FSNOTIFY_EVENT_DENTRY, dir, &dentry->d_name, 0);
62 }
63 
fsnotify_inode(struct inode * inode,__u32 mask)64 static inline void fsnotify_inode(struct inode *inode, __u32 mask)
65 {
66 	if (!fsnotify_sb_has_watchers(inode->i_sb))
67 		return;
68 
69 	if (S_ISDIR(inode->i_mode))
70 		mask |= FS_ISDIR;
71 
72 	fsnotify(mask, inode, FSNOTIFY_EVENT_INODE, NULL, NULL, inode, 0);
73 }
74 
75 /* Notify this dentry's parent about a child's events. */
fsnotify_parent(struct dentry * dentry,__u32 mask,const void * data,int data_type)76 static 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(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 
98 notify_child:
99 	return fsnotify(mask, data, data_type, NULL, NULL, inode, 0);
100 }
101 
102 /*
103  * Simple wrappers to consolidate calls to fsnotify_parent() when an event
104  * is on a file/dentry.
105  */
fsnotify_dentry(struct dentry * dentry,__u32 mask)106 static inline void fsnotify_dentry(struct dentry *dentry, __u32 mask)
107 {
108 	fsnotify_parent(dentry, mask, dentry, FSNOTIFY_EVENT_DENTRY);
109 }
110 
fsnotify_path(const struct path * path,__u32 mask)111 static inline int fsnotify_path(const struct path *path, __u32 mask)
112 {
113 	return fsnotify_parent(path->dentry, mask, path, FSNOTIFY_EVENT_PATH);
114 }
115 
fsnotify_file(struct file * file,__u32 mask)116 static 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(&file->f_path, mask);
128 }
129 
130 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
131 
132 void file_set_fsnotify_mode_from_watchers(struct file *file);
133 
134 /*
135  * fsnotify_file_area_perm - permission hook before access to file range
136  */
fsnotify_file_area_perm(struct file * file,int perm_mask,const loff_t * ppos,size_t count)137 static 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 	if (likely(!FMODE_FSNOTIFY_PERM(file->f_mode)))
151 		return 0;
152 
153 	/*
154 	 * read()/write() and other types of access generate pre-content events.
155 	 */
156 	if (unlikely(FMODE_FSNOTIFY_HSM(file->f_mode))) {
157 		int ret = fsnotify_pre_content(&file->f_path, ppos, count);
158 
159 		if (ret)
160 			return ret;
161 	}
162 
163 	if (!(perm_mask & MAY_READ))
164 		return 0;
165 
166 	/*
167 	 * read() also generates the legacy FS_ACCESS_PERM event, so content
168 	 * scanners can inspect the content filled by pre-content event.
169 	 */
170 	return fsnotify_path(&file->f_path, FS_ACCESS_PERM);
171 }
172 
173 /*
174  * fsnotify_mmap_perm - permission hook before mmap of file range
175  */
fsnotify_mmap_perm(struct file * file,int prot,const loff_t off,size_t len)176 static inline int fsnotify_mmap_perm(struct file *file, int prot,
177 				     const loff_t off, size_t len)
178 {
179 	/*
180 	 * mmap() generates only pre-content events.
181 	 */
182 	if (!file || likely(!FMODE_FSNOTIFY_HSM(file->f_mode)))
183 		return 0;
184 
185 	return fsnotify_pre_content(&file->f_path, &off, len);
186 }
187 
188 /*
189  * fsnotify_truncate_perm - permission hook before file truncate
190  */
fsnotify_truncate_perm(const struct path * path,loff_t length)191 static inline int fsnotify_truncate_perm(const struct path *path, loff_t length)
192 {
193 	struct inode *inode = d_inode(path->dentry);
194 
195 	if (!(inode->i_sb->s_iflags & SB_I_ALLOW_HSM) ||
196 	    !fsnotify_sb_has_priority_watchers(inode->i_sb,
197 					       FSNOTIFY_PRIO_PRE_CONTENT))
198 		return 0;
199 
200 	return fsnotify_pre_content(path, &length, 0);
201 }
202 
203 /*
204  * fsnotify_file_perm - permission hook before file access (unknown range)
205  */
fsnotify_file_perm(struct file * file,int perm_mask)206 static inline int fsnotify_file_perm(struct file *file, int perm_mask)
207 {
208 	return fsnotify_file_area_perm(file, perm_mask, NULL, 0);
209 }
210 
211 /*
212  * fsnotify_open_perm - permission hook before file open
213  */
fsnotify_open_perm(struct file * file)214 static inline int fsnotify_open_perm(struct file *file)
215 {
216 	int ret;
217 
218 	if (likely(!FMODE_FSNOTIFY_PERM(file->f_mode)))
219 		return 0;
220 
221 	if (file->f_flags & __FMODE_EXEC) {
222 		ret = fsnotify_path(&file->f_path, FS_OPEN_EXEC_PERM);
223 		if (ret)
224 			return ret;
225 	}
226 
227 	return fsnotify_path(&file->f_path, FS_OPEN_PERM);
228 }
229 
230 #else
file_set_fsnotify_mode_from_watchers(struct file * file)231 static inline void file_set_fsnotify_mode_from_watchers(struct file *file)
232 {
233 }
234 
fsnotify_file_area_perm(struct file * file,int perm_mask,const loff_t * ppos,size_t count)235 static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
236 					  const loff_t *ppos, size_t count)
237 {
238 	return 0;
239 }
240 
fsnotify_mmap_perm(struct file * file,int prot,const loff_t off,size_t len)241 static inline int fsnotify_mmap_perm(struct file *file, int prot,
242 				     const loff_t off, size_t len)
243 {
244 	return 0;
245 }
246 
fsnotify_truncate_perm(const struct path * path,loff_t length)247 static inline int fsnotify_truncate_perm(const struct path *path, loff_t length)
248 {
249 	return 0;
250 }
251 
fsnotify_file_perm(struct file * file,int perm_mask)252 static inline int fsnotify_file_perm(struct file *file, int perm_mask)
253 {
254 	return 0;
255 }
256 
fsnotify_open_perm(struct file * file)257 static inline int fsnotify_open_perm(struct file *file)
258 {
259 	return 0;
260 }
261 #endif
262 
263 /*
264  * fsnotify_link_count - inode's link count changed
265  */
fsnotify_link_count(struct inode * inode)266 static inline void fsnotify_link_count(struct inode *inode)
267 {
268 	fsnotify_inode(inode, FS_ATTRIB);
269 }
270 
271 /*
272  * fsnotify_move - file old_name at old_dir was moved to new_name at new_dir
273  */
fsnotify_move(struct inode * old_dir,struct inode * new_dir,const struct qstr * old_name,int isdir,struct inode * target,struct dentry * moved)274 static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
275 				 const struct qstr *old_name,
276 				 int isdir, struct inode *target,
277 				 struct dentry *moved)
278 {
279 	struct inode *source = moved->d_inode;
280 	u32 fs_cookie = fsnotify_get_cookie();
281 	__u32 old_dir_mask = FS_MOVED_FROM;
282 	__u32 new_dir_mask = FS_MOVED_TO;
283 	__u32 rename_mask = FS_RENAME;
284 	const struct qstr *new_name = &moved->d_name;
285 
286 	if (isdir) {
287 		old_dir_mask |= FS_ISDIR;
288 		new_dir_mask |= FS_ISDIR;
289 		rename_mask |= FS_ISDIR;
290 	}
291 
292 	/* Event with information about both old and new parent+name */
293 	fsnotify_name(rename_mask, moved, FSNOTIFY_EVENT_DENTRY,
294 		      old_dir, old_name, 0);
295 
296 	fsnotify_name(old_dir_mask, source, FSNOTIFY_EVENT_INODE,
297 		      old_dir, old_name, fs_cookie);
298 	fsnotify_name(new_dir_mask, source, FSNOTIFY_EVENT_INODE,
299 		      new_dir, new_name, fs_cookie);
300 
301 	if (target)
302 		fsnotify_link_count(target);
303 	fsnotify_inode(source, FS_MOVE_SELF);
304 	audit_inode_child(new_dir, moved, AUDIT_TYPE_CHILD_CREATE);
305 }
306 
307 /*
308  * fsnotify_inode_delete - and inode is being evicted from cache, clean up is needed
309  */
fsnotify_inode_delete(struct inode * inode)310 static inline void fsnotify_inode_delete(struct inode *inode)
311 {
312 	__fsnotify_inode_delete(inode);
313 }
314 
315 /*
316  * fsnotify_vfsmount_delete - a vfsmount is being destroyed, clean up is needed
317  */
fsnotify_vfsmount_delete(struct vfsmount * mnt)318 static inline void fsnotify_vfsmount_delete(struct vfsmount *mnt)
319 {
320 	__fsnotify_vfsmount_delete(mnt);
321 }
322 
fsnotify_mntns_delete(struct mnt_namespace * mntns)323 static inline void fsnotify_mntns_delete(struct mnt_namespace *mntns)
324 {
325 	__fsnotify_mntns_delete(mntns);
326 }
327 
328 /*
329  * fsnotify_inoderemove - an inode is going away
330  */
fsnotify_inoderemove(struct inode * inode)331 static inline void fsnotify_inoderemove(struct inode *inode)
332 {
333 	fsnotify_inode(inode, FS_DELETE_SELF);
334 	__fsnotify_inode_delete(inode);
335 }
336 
337 /*
338  * fsnotify_create - 'name' was linked in
339  *
340  * Caller must make sure that dentry->d_name is stable.
341  * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
342  * ->d_inode later
343  */
fsnotify_create(struct inode * dir,struct dentry * dentry)344 static inline void fsnotify_create(struct inode *dir, struct dentry *dentry)
345 {
346 	audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);
347 
348 	fsnotify_dirent(dir, dentry, FS_CREATE);
349 }
350 
351 /*
352  * fsnotify_link - new hardlink in 'inode' directory
353  *
354  * Caller must make sure that new_dentry->d_name is stable.
355  * Note: We have to pass also the linked inode ptr as some filesystems leave
356  *   new_dentry->d_inode NULL and instantiate inode pointer later
357  */
fsnotify_link(struct inode * dir,struct inode * inode,struct dentry * new_dentry)358 static inline void fsnotify_link(struct inode *dir, struct inode *inode,
359 				 struct dentry *new_dentry)
360 {
361 	fsnotify_link_count(inode);
362 	audit_inode_child(dir, new_dentry, AUDIT_TYPE_CHILD_CREATE);
363 
364 	fsnotify_name(FS_CREATE, inode, FSNOTIFY_EVENT_INODE,
365 		      dir, &new_dentry->d_name, 0);
366 }
367 
368 /*
369  * fsnotify_delete - @dentry was unlinked and unhashed
370  *
371  * Caller must make sure that dentry->d_name is stable.
372  *
373  * Note: unlike fsnotify_unlink(), we have to pass also the unlinked inode
374  * as this may be called after d_delete() and old_dentry may be negative.
375  */
fsnotify_delete(struct inode * dir,struct inode * inode,struct dentry * dentry)376 static inline void fsnotify_delete(struct inode *dir, struct inode *inode,
377 				   struct dentry *dentry)
378 {
379 	__u32 mask = FS_DELETE;
380 
381 	if (S_ISDIR(inode->i_mode))
382 		mask |= FS_ISDIR;
383 
384 	fsnotify_name(mask, inode, FSNOTIFY_EVENT_INODE, dir, &dentry->d_name,
385 		      0);
386 }
387 
388 /**
389  * d_delete_notify - delete a dentry and call fsnotify_delete()
390  * @dentry: The dentry to delete
391  *
392  * This helper is used to guaranty that the unlinked inode cannot be found
393  * by lookup of this name after fsnotify_delete() event has been delivered.
394  */
d_delete_notify(struct inode * dir,struct dentry * dentry)395 static inline void d_delete_notify(struct inode *dir, struct dentry *dentry)
396 {
397 	struct inode *inode = d_inode(dentry);
398 
399 	ihold(inode);
400 	d_delete(dentry);
401 	fsnotify_delete(dir, inode, dentry);
402 	iput(inode);
403 }
404 
405 /*
406  * fsnotify_unlink - 'name' was unlinked
407  *
408  * Caller must make sure that dentry->d_name is stable.
409  */
fsnotify_unlink(struct inode * dir,struct dentry * dentry)410 static inline void fsnotify_unlink(struct inode *dir, struct dentry *dentry)
411 {
412 	if (WARN_ON_ONCE(d_is_negative(dentry)))
413 		return;
414 
415 	fsnotify_delete(dir, d_inode(dentry), dentry);
416 }
417 
418 /*
419  * fsnotify_mkdir - directory 'name' was created
420  *
421  * Caller must make sure that dentry->d_name is stable.
422  * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
423  * ->d_inode later
424  */
fsnotify_mkdir(struct inode * dir,struct dentry * dentry)425 static inline void fsnotify_mkdir(struct inode *dir, struct dentry *dentry)
426 {
427 	audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);
428 
429 	fsnotify_dirent(dir, dentry, FS_CREATE | FS_ISDIR);
430 }
431 
432 /*
433  * fsnotify_rmdir - directory 'name' was removed
434  *
435  * Caller must make sure that dentry->d_name is stable.
436  */
fsnotify_rmdir(struct inode * dir,struct dentry * dentry)437 static inline void fsnotify_rmdir(struct inode *dir, struct dentry *dentry)
438 {
439 	if (WARN_ON_ONCE(d_is_negative(dentry)))
440 		return;
441 
442 	fsnotify_delete(dir, d_inode(dentry), dentry);
443 }
444 
445 /*
446  * fsnotify_access - file was read
447  */
fsnotify_access(struct file * file)448 static inline void fsnotify_access(struct file *file)
449 {
450 	fsnotify_file(file, FS_ACCESS);
451 }
452 
453 /*
454  * fsnotify_modify - file was modified
455  */
fsnotify_modify(struct file * file)456 static inline void fsnotify_modify(struct file *file)
457 {
458 	fsnotify_file(file, FS_MODIFY);
459 }
460 
461 /*
462  * fsnotify_open - file was opened
463  */
fsnotify_open(struct file * file)464 static inline void fsnotify_open(struct file *file)
465 {
466 	__u32 mask = FS_OPEN;
467 
468 	if (file->f_flags & __FMODE_EXEC)
469 		mask |= FS_OPEN_EXEC;
470 
471 	fsnotify_file(file, mask);
472 }
473 
474 /*
475  * fsnotify_close - file was closed
476  */
fsnotify_close(struct file * file)477 static inline void fsnotify_close(struct file *file)
478 {
479 	__u32 mask = (file->f_mode & FMODE_WRITE) ? FS_CLOSE_WRITE :
480 						    FS_CLOSE_NOWRITE;
481 
482 	fsnotify_file(file, mask);
483 }
484 
485 /*
486  * fsnotify_xattr - extended attributes were changed
487  */
fsnotify_xattr(struct dentry * dentry)488 static inline void fsnotify_xattr(struct dentry *dentry)
489 {
490 	fsnotify_dentry(dentry, FS_ATTRIB);
491 }
492 
493 /*
494  * fsnotify_change - notify_change event.  file was modified and/or metadata
495  * was changed.
496  */
fsnotify_change(struct dentry * dentry,unsigned int ia_valid)497 static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
498 {
499 	__u32 mask = 0;
500 
501 	if (ia_valid & ATTR_UID)
502 		mask |= FS_ATTRIB;
503 	if (ia_valid & ATTR_GID)
504 		mask |= FS_ATTRIB;
505 	if (ia_valid & ATTR_SIZE)
506 		mask |= FS_MODIFY;
507 
508 	/* both times implies a utime(s) call */
509 	if ((ia_valid & (ATTR_ATIME | ATTR_MTIME)) == (ATTR_ATIME | ATTR_MTIME))
510 		mask |= FS_ATTRIB;
511 	else if (ia_valid & ATTR_ATIME)
512 		mask |= FS_ACCESS;
513 	else if (ia_valid & ATTR_MTIME)
514 		mask |= FS_MODIFY;
515 
516 	if (ia_valid & ATTR_MODE)
517 		mask |= FS_ATTRIB;
518 
519 	if (mask)
520 		fsnotify_dentry(dentry, mask);
521 }
522 
fsnotify_sb_error(struct super_block * sb,struct inode * inode,int error)523 static inline int fsnotify_sb_error(struct super_block *sb, struct inode *inode,
524 				    int error)
525 {
526 	struct fs_error_report report = {
527 		.error = error,
528 		.inode = inode,
529 		.sb = sb,
530 	};
531 
532 	return fsnotify(FS_ERROR, &report, FSNOTIFY_EVENT_ERROR,
533 			NULL, NULL, NULL, 0);
534 }
535 
fsnotify_mnt_attach(struct mnt_namespace * ns,struct vfsmount * mnt)536 static inline void fsnotify_mnt_attach(struct mnt_namespace *ns, struct vfsmount *mnt)
537 {
538 	fsnotify_mnt(FS_MNT_ATTACH, ns, mnt);
539 }
540 
fsnotify_mnt_detach(struct mnt_namespace * ns,struct vfsmount * mnt)541 static inline void fsnotify_mnt_detach(struct mnt_namespace *ns, struct vfsmount *mnt)
542 {
543 	fsnotify_mnt(FS_MNT_DETACH, ns, mnt);
544 }
545 
fsnotify_mnt_move(struct mnt_namespace * ns,struct vfsmount * mnt)546 static inline void fsnotify_mnt_move(struct mnt_namespace *ns, struct vfsmount *mnt)
547 {
548 	fsnotify_mnt(FS_MNT_MOVE, ns, mnt);
549 }
550 
551 #endif	/* _LINUX_FS_NOTIFY_H */
552