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_file(struct file * file,__u32 mask)111 static inline int fsnotify_file(struct file *file, __u32 mask)
112 {
113 const struct path *path;
114
115 if (file->f_mode & FMODE_NONOTIFY)
116 return 0;
117
118 path = &file->f_path;
119 /* Permission events require group prio >= FSNOTIFY_PRIO_CONTENT */
120 if (mask & ALL_FSNOTIFY_PERM_EVENTS &&
121 !fsnotify_sb_has_priority_watchers(path->dentry->d_sb,
122 FSNOTIFY_PRIO_CONTENT))
123 return 0;
124
125 return fsnotify_parent(path->dentry, mask, path, FSNOTIFY_EVENT_PATH);
126 }
127
128 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
129 /*
130 * fsnotify_file_area_perm - permission hook before access to file range
131 */
fsnotify_file_area_perm(struct file * file,int perm_mask,const loff_t * ppos,size_t count)132 static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
133 const loff_t *ppos, size_t count)
134 {
135 __u32 fsnotify_mask = FS_ACCESS_PERM;
136
137 /*
138 * filesystem may be modified in the context of permission events
139 * (e.g. by HSM filling a file on access), so sb freeze protection
140 * must not be held.
141 */
142 lockdep_assert_once(file_write_not_started(file));
143
144 if (!(perm_mask & MAY_READ))
145 return 0;
146
147 return fsnotify_file(file, fsnotify_mask);
148 }
149
150 /*
151 * fsnotify_file_perm - permission hook before file access
152 */
fsnotify_file_perm(struct file * file,int perm_mask)153 static inline int fsnotify_file_perm(struct file *file, int perm_mask)
154 {
155 return fsnotify_file_area_perm(file, perm_mask, NULL, 0);
156 }
157
158 /*
159 * fsnotify_open_perm - permission hook before file open
160 */
fsnotify_open_perm(struct file * file)161 static inline int fsnotify_open_perm(struct file *file)
162 {
163 int ret;
164
165 if (file->f_flags & __FMODE_EXEC) {
166 ret = fsnotify_file(file, FS_OPEN_EXEC_PERM);
167 if (ret)
168 return ret;
169 }
170
171 return fsnotify_file(file, FS_OPEN_PERM);
172 }
173
174 #else
fsnotify_file_area_perm(struct file * file,int perm_mask,const loff_t * ppos,size_t count)175 static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
176 const loff_t *ppos, size_t count)
177 {
178 return 0;
179 }
180
fsnotify_file_perm(struct file * file,int perm_mask)181 static inline int fsnotify_file_perm(struct file *file, int perm_mask)
182 {
183 return 0;
184 }
185
fsnotify_open_perm(struct file * file)186 static inline int fsnotify_open_perm(struct file *file)
187 {
188 return 0;
189 }
190 #endif
191
192 /*
193 * fsnotify_link_count - inode's link count changed
194 */
fsnotify_link_count(struct inode * inode)195 static inline void fsnotify_link_count(struct inode *inode)
196 {
197 fsnotify_inode(inode, FS_ATTRIB);
198 }
199
200 /*
201 * fsnotify_move - file old_name at old_dir was moved to new_name at new_dir
202 */
fsnotify_move(struct inode * old_dir,struct inode * new_dir,const struct qstr * old_name,int isdir,struct inode * target,struct dentry * moved)203 static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
204 const struct qstr *old_name,
205 int isdir, struct inode *target,
206 struct dentry *moved)
207 {
208 struct inode *source = moved->d_inode;
209 u32 fs_cookie = fsnotify_get_cookie();
210 __u32 old_dir_mask = FS_MOVED_FROM;
211 __u32 new_dir_mask = FS_MOVED_TO;
212 __u32 rename_mask = FS_RENAME;
213 const struct qstr *new_name = &moved->d_name;
214
215 if (isdir) {
216 old_dir_mask |= FS_ISDIR;
217 new_dir_mask |= FS_ISDIR;
218 rename_mask |= FS_ISDIR;
219 }
220
221 /* Event with information about both old and new parent+name */
222 fsnotify_name(rename_mask, moved, FSNOTIFY_EVENT_DENTRY,
223 old_dir, old_name, 0);
224
225 fsnotify_name(old_dir_mask, source, FSNOTIFY_EVENT_INODE,
226 old_dir, old_name, fs_cookie);
227 fsnotify_name(new_dir_mask, source, FSNOTIFY_EVENT_INODE,
228 new_dir, new_name, fs_cookie);
229
230 if (target)
231 fsnotify_link_count(target);
232 fsnotify_inode(source, FS_MOVE_SELF);
233 audit_inode_child(new_dir, moved, AUDIT_TYPE_CHILD_CREATE);
234 }
235
236 /*
237 * fsnotify_inode_delete - and inode is being evicted from cache, clean up is needed
238 */
fsnotify_inode_delete(struct inode * inode)239 static inline void fsnotify_inode_delete(struct inode *inode)
240 {
241 __fsnotify_inode_delete(inode);
242 }
243
244 /*
245 * fsnotify_vfsmount_delete - a vfsmount is being destroyed, clean up is needed
246 */
fsnotify_vfsmount_delete(struct vfsmount * mnt)247 static inline void fsnotify_vfsmount_delete(struct vfsmount *mnt)
248 {
249 __fsnotify_vfsmount_delete(mnt);
250 }
251
252 /*
253 * fsnotify_inoderemove - an inode is going away
254 */
fsnotify_inoderemove(struct inode * inode)255 static inline void fsnotify_inoderemove(struct inode *inode)
256 {
257 fsnotify_inode(inode, FS_DELETE_SELF);
258 __fsnotify_inode_delete(inode);
259 }
260
261 /*
262 * fsnotify_create - 'name' was linked in
263 *
264 * Caller must make sure that dentry->d_name is stable.
265 * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
266 * ->d_inode later
267 */
fsnotify_create(struct inode * dir,struct dentry * dentry)268 static inline void fsnotify_create(struct inode *dir, struct dentry *dentry)
269 {
270 audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);
271
272 fsnotify_dirent(dir, dentry, FS_CREATE);
273 }
274
275 /*
276 * fsnotify_link - new hardlink in 'inode' directory
277 *
278 * Caller must make sure that new_dentry->d_name is stable.
279 * Note: We have to pass also the linked inode ptr as some filesystems leave
280 * new_dentry->d_inode NULL and instantiate inode pointer later
281 */
fsnotify_link(struct inode * dir,struct inode * inode,struct dentry * new_dentry)282 static inline void fsnotify_link(struct inode *dir, struct inode *inode,
283 struct dentry *new_dentry)
284 {
285 fsnotify_link_count(inode);
286 audit_inode_child(dir, new_dentry, AUDIT_TYPE_CHILD_CREATE);
287
288 fsnotify_name(FS_CREATE, inode, FSNOTIFY_EVENT_INODE,
289 dir, &new_dentry->d_name, 0);
290 }
291
292 /*
293 * fsnotify_delete - @dentry was unlinked and unhashed
294 *
295 * Caller must make sure that dentry->d_name is stable.
296 *
297 * Note: unlike fsnotify_unlink(), we have to pass also the unlinked inode
298 * as this may be called after d_delete() and old_dentry may be negative.
299 */
fsnotify_delete(struct inode * dir,struct inode * inode,struct dentry * dentry)300 static inline void fsnotify_delete(struct inode *dir, struct inode *inode,
301 struct dentry *dentry)
302 {
303 __u32 mask = FS_DELETE;
304
305 if (S_ISDIR(inode->i_mode))
306 mask |= FS_ISDIR;
307
308 fsnotify_name(mask, inode, FSNOTIFY_EVENT_INODE, dir, &dentry->d_name,
309 0);
310 }
311
312 /**
313 * d_delete_notify - delete a dentry and call fsnotify_delete()
314 * @dentry: The dentry to delete
315 *
316 * This helper is used to guaranty that the unlinked inode cannot be found
317 * by lookup of this name after fsnotify_delete() event has been delivered.
318 */
d_delete_notify(struct inode * dir,struct dentry * dentry)319 static inline void d_delete_notify(struct inode *dir, struct dentry *dentry)
320 {
321 struct inode *inode = d_inode(dentry);
322
323 ihold(inode);
324 d_delete(dentry);
325 fsnotify_delete(dir, inode, dentry);
326 iput(inode);
327 }
328
329 /*
330 * fsnotify_unlink - 'name' was unlinked
331 *
332 * Caller must make sure that dentry->d_name is stable.
333 */
fsnotify_unlink(struct inode * dir,struct dentry * dentry)334 static inline void fsnotify_unlink(struct inode *dir, struct dentry *dentry)
335 {
336 if (WARN_ON_ONCE(d_is_negative(dentry)))
337 return;
338
339 fsnotify_delete(dir, d_inode(dentry), dentry);
340 }
341
342 /*
343 * fsnotify_mkdir - directory 'name' was created
344 *
345 * Caller must make sure that dentry->d_name is stable.
346 * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
347 * ->d_inode later
348 */
fsnotify_mkdir(struct inode * dir,struct dentry * dentry)349 static inline void fsnotify_mkdir(struct inode *dir, struct dentry *dentry)
350 {
351 audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);
352
353 fsnotify_dirent(dir, dentry, FS_CREATE | FS_ISDIR);
354 }
355
356 /*
357 * fsnotify_rmdir - directory 'name' was removed
358 *
359 * Caller must make sure that dentry->d_name is stable.
360 */
fsnotify_rmdir(struct inode * dir,struct dentry * dentry)361 static inline void fsnotify_rmdir(struct inode *dir, struct dentry *dentry)
362 {
363 if (WARN_ON_ONCE(d_is_negative(dentry)))
364 return;
365
366 fsnotify_delete(dir, d_inode(dentry), dentry);
367 }
368
369 /*
370 * fsnotify_access - file was read
371 */
fsnotify_access(struct file * file)372 static inline void fsnotify_access(struct file *file)
373 {
374 fsnotify_file(file, FS_ACCESS);
375 }
376
377 /*
378 * fsnotify_modify - file was modified
379 */
fsnotify_modify(struct file * file)380 static inline void fsnotify_modify(struct file *file)
381 {
382 fsnotify_file(file, FS_MODIFY);
383 }
384
385 /*
386 * fsnotify_open - file was opened
387 */
fsnotify_open(struct file * file)388 static inline void fsnotify_open(struct file *file)
389 {
390 __u32 mask = FS_OPEN;
391
392 if (file->f_flags & __FMODE_EXEC)
393 mask |= FS_OPEN_EXEC;
394
395 fsnotify_file(file, mask);
396 }
397
398 /*
399 * fsnotify_close - file was closed
400 */
fsnotify_close(struct file * file)401 static inline void fsnotify_close(struct file *file)
402 {
403 __u32 mask = (file->f_mode & FMODE_WRITE) ? FS_CLOSE_WRITE :
404 FS_CLOSE_NOWRITE;
405
406 fsnotify_file(file, mask);
407 }
408
409 /*
410 * fsnotify_xattr - extended attributes were changed
411 */
fsnotify_xattr(struct dentry * dentry)412 static inline void fsnotify_xattr(struct dentry *dentry)
413 {
414 fsnotify_dentry(dentry, FS_ATTRIB);
415 }
416
417 /*
418 * fsnotify_change - notify_change event. file was modified and/or metadata
419 * was changed.
420 */
fsnotify_change(struct dentry * dentry,unsigned int ia_valid)421 static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
422 {
423 __u32 mask = 0;
424
425 if (ia_valid & ATTR_UID)
426 mask |= FS_ATTRIB;
427 if (ia_valid & ATTR_GID)
428 mask |= FS_ATTRIB;
429 if (ia_valid & ATTR_SIZE)
430 mask |= FS_MODIFY;
431
432 /* both times implies a utime(s) call */
433 if ((ia_valid & (ATTR_ATIME | ATTR_MTIME)) == (ATTR_ATIME | ATTR_MTIME))
434 mask |= FS_ATTRIB;
435 else if (ia_valid & ATTR_ATIME)
436 mask |= FS_ACCESS;
437 else if (ia_valid & ATTR_MTIME)
438 mask |= FS_MODIFY;
439
440 if (ia_valid & ATTR_MODE)
441 mask |= FS_ATTRIB;
442
443 if (mask)
444 fsnotify_dentry(dentry, mask);
445 }
446
fsnotify_sb_error(struct super_block * sb,struct inode * inode,int error)447 static inline int fsnotify_sb_error(struct super_block *sb, struct inode *inode,
448 int error)
449 {
450 struct fs_error_report report = {
451 .error = error,
452 .inode = inode,
453 .sb = sb,
454 };
455
456 return fsnotify(FS_ERROR, &report, FSNOTIFY_EVENT_ERROR,
457 NULL, NULL, NULL, 0);
458 }
459
460 #endif /* _LINUX_FS_NOTIFY_H */
461