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