fsnotify.h

  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(&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, 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(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, dentry, FSNOTIFY_EVENT_DENTRY, dir, &dentry->d_name, 0);
 62}
 63
 64static 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. */
 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(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, 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, dentry, FSNOTIFY_EVENT_DENTRY);
109}
110
111static inline int fsnotify_path(const struct path *path, __u32 mask)
112{
113	return fsnotify_parent(path->dentry, mask, path, 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(&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(rename_mask, moved, FSNOTIFY_EVENT_DENTRY,
269		      old_dir, old_name, 0);
270
271	fsnotify_name(old_dir_mask, source, FSNOTIFY_EVENT_INODE,
272		      old_dir, old_name, fs_cookie);
273	fsnotify_name(new_dir_mask, source, FSNOTIFY_EVENT_INODE,
274		      new_dir, new_name, fs_cookie);
275
276	if (target)
277		fsnotify_link_count(target);
278	fsnotify_inode(source, FS_MOVE_SELF);
279	audit_inode_child(new_dir, 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(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(dir, new_dentry, AUDIT_TYPE_CHILD_CREATE);
338
339	fsnotify_name(FS_CREATE, inode, FSNOTIFY_EVENT_INODE,
340		      dir, &new_dentry->d_name, 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, inode, FSNOTIFY_EVENT_INODE, dir, &dentry->d_name,
360		      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, 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(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, 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, &report, FSNOTIFY_EVENT_ERROR,
508			NULL, NULL, NULL, 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 */