include/linux/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 /*
  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  */
  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
  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
  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. */
  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  */
  87 static inline void fsnotify_dentry(struct dentry *dentry, __u32 mask)
  88 {
  89         fsnotify_parent(dentry, mask, dentry, FSNOTIFY_EVENT_DENTRY);
  90 }
  91
  92 static inline int fsnotify_file(struct file *file, __u32 mask)
  93 {
  94         const struct path *path;
  95
  96         if (file->f_mode & FMODE_NONOTIFY)
  97                 return 0;
  98
  99         path = &file->f_path;
 100         return fsnotify_parent(path->dentry, mask, path, FSNOTIFY_EVENT_PATH);
 101 }
 102
 103 /* Simple call site for access decisions */
 104 static inline int fsnotify_perm(struct file *file, int mask)
 105 {
 106         int ret;
 107         __u32 fsnotify_mask = 0;
 108
 109         if (!(mask & (MAY_READ | MAY_OPEN)))
 110                 return 0;
 111
 112         if (mask & MAY_OPEN) {
 113                 fsnotify_mask = FS_OPEN_PERM;
 114
 115                 if (file->f_flags & __FMODE_EXEC) {
 116                         ret = fsnotify_file(file, FS_OPEN_EXEC_PERM);
 117
 118                         if (ret)
 119                                 return ret;
 120                 }
 121         } else if (mask & MAY_READ) {
 122                 fsnotify_mask = FS_ACCESS_PERM;
 123         }
 124
 125         return fsnotify_file(file, fsnotify_mask);
 126 }
 127
 128 /*
 129  * fsnotify_link_count - inode's link count changed
 130  */
 131 static inline void fsnotify_link_count(struct inode *inode)
 132 {
 133         fsnotify_inode(inode, FS_ATTRIB);
 134 }
 135
 136 /*
 137  * fsnotify_move - file old_name at old_dir was moved to new_name at new_dir
 138  */
 139 static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
 140                                  const struct qstr *old_name,
 141                                  int isdir, struct inode *target,
 142                                  struct dentry *moved)
 143 {
 144         struct inode *source = moved->d_inode;
 145         u32 fs_cookie = fsnotify_get_cookie();
 146         __u32 old_dir_mask = FS_MOVED_FROM;
 147         __u32 new_dir_mask = FS_MOVED_TO;
 148         __u32 rename_mask = FS_RENAME;
 149         const struct qstr *new_name = &moved->d_name;
 150
 151         if (isdir) {
 152                 old_dir_mask |= FS_ISDIR;
 153                 new_dir_mask |= FS_ISDIR;
 154                 rename_mask |= FS_ISDIR;
 155         }
 156
 157         /* Event with information about both old and new parent+name */
 158         fsnotify_name(rename_mask, moved, FSNOTIFY_EVENT_DENTRY,
 159                       old_dir, old_name, 0);
 160
 161         fsnotify_name(old_dir_mask, source, FSNOTIFY_EVENT_INODE,
 162                       old_dir, old_name, fs_cookie);
 163         fsnotify_name(new_dir_mask, source, FSNOTIFY_EVENT_INODE,
 164                       new_dir, new_name, fs_cookie);
 165
 166         if (target)
 167                 fsnotify_link_count(target);
 168         fsnotify_inode(source, FS_MOVE_SELF);
 169         audit_inode_child(new_dir, moved, AUDIT_TYPE_CHILD_CREATE);
 170 }
 171
 172 /*
 173  * fsnotify_inode_delete - and inode is being evicted from cache, clean up is needed
 174  */
 175 static inline void fsnotify_inode_delete(struct inode *inode)
 176 {
 177         __fsnotify_inode_delete(inode);
 178 }
 179
 180 /*
 181  * fsnotify_vfsmount_delete - a vfsmount is being destroyed, clean up is needed
 182  */
 183 static inline void fsnotify_vfsmount_delete(struct vfsmount *mnt)
 184 {
 185         __fsnotify_vfsmount_delete(mnt);
 186 }
 187
 188 /*
 189  * fsnotify_inoderemove - an inode is going away
 190  */
 191 static inline void fsnotify_inoderemove(struct inode *inode)
 192 {
 193         fsnotify_inode(inode, FS_DELETE_SELF);
 194         __fsnotify_inode_delete(inode);
 195 }
 196
 197 /*
 198  * fsnotify_create - 'name' was linked in
 199  *
 200  * Caller must make sure that dentry->d_name is stable.
 201  * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
 202  * ->d_inode later
 203  */
 204 static inline void fsnotify_create(struct inode *dir, struct dentry *dentry)
 205 {
 206         audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);
 207
 208         fsnotify_dirent(dir, dentry, FS_CREATE);
 209 }
 210
 211 /*
 212  * fsnotify_link - new hardlink in 'inode' directory
 213  *
 214  * Caller must make sure that new_dentry->d_name is stable.
 215  * Note: We have to pass also the linked inode ptr as some filesystems leave
 216  *   new_dentry->d_inode NULL and instantiate inode pointer later
 217  */
 218 static inline void fsnotify_link(struct inode *dir, struct inode *inode,
 219                                  struct dentry *new_dentry)
 220 {
 221         fsnotify_link_count(inode);
 222         audit_inode_child(dir, new_dentry, AUDIT_TYPE_CHILD_CREATE);
 223
 224         fsnotify_name(FS_CREATE, inode, FSNOTIFY_EVENT_INODE,
 225                       dir, &new_dentry->d_name, 0);
 226 }
 227
 228 /*
 229  * fsnotify_delete - @dentry was unlinked and unhashed
 230  *
 231  * Caller must make sure that dentry->d_name is stable.
 232  *
 233  * Note: unlike fsnotify_unlink(), we have to pass also the unlinked inode
 234  * as this may be called after d_delete() and old_dentry may be negative.
 235  */
 236 static inline void fsnotify_delete(struct inode *dir, struct inode *inode,
 237                                    struct dentry *dentry)
 238 {
 239         __u32 mask = FS_DELETE;
 240
 241         if (S_ISDIR(inode->i_mode))
 242                 mask |= FS_ISDIR;
 243
 244         fsnotify_name(mask, inode, FSNOTIFY_EVENT_INODE, dir, &dentry->d_name,
 245                       0);
 246 }
 247
 248 /**
 249  * d_delete_notify - delete a dentry and call fsnotify_delete()
 250  * @dentry: The dentry to delete
 251  *
 252  * This helper is used to guaranty that the unlinked inode cannot be found
 253  * by lookup of this name after fsnotify_delete() event has been delivered.
 254  */
 255 static inline void d_delete_notify(struct inode *dir, struct dentry *dentry)
 256 {
 257         struct inode *inode = d_inode(dentry);
 258
 259         ihold(inode);
 260         d_delete(dentry);
 261         fsnotify_delete(dir, inode, dentry);
 262         iput(inode);
 263 }
 264
 265 /*
 266  * fsnotify_unlink - 'name' was unlinked
 267  *
 268  * Caller must make sure that dentry->d_name is stable.
 269  */
 270 static inline void fsnotify_unlink(struct inode *dir, struct dentry *dentry)
 271 {
 272         if (WARN_ON_ONCE(d_is_negative(dentry)))
 273                 return;
 274
 275         fsnotify_delete(dir, d_inode(dentry), dentry);
 276 }
 277
 278 /*
 279  * fsnotify_mkdir - directory 'name' was created
 280  *
 281  * Caller must make sure that dentry->d_name is stable.
 282  * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
 283  * ->d_inode later
 284  */
 285 static inline void fsnotify_mkdir(struct inode *dir, struct dentry *dentry)
 286 {
 287         audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);
 288
 289         fsnotify_dirent(dir, dentry, FS_CREATE | FS_ISDIR);
 290 }
 291
 292 /*
 293  * fsnotify_rmdir - directory 'name' was removed
 294  *
 295  * Caller must make sure that dentry->d_name is stable.
 296  */
 297 static inline void fsnotify_rmdir(struct inode *dir, struct dentry *dentry)
 298 {
 299         if (WARN_ON_ONCE(d_is_negative(dentry)))
 300                 return;
 301
 302         fsnotify_delete(dir, d_inode(dentry), dentry);
 303 }
 304
 305 /*
 306  * fsnotify_access - file was read
 307  */
 308 static inline void fsnotify_access(struct file *file)
 309 {
 310         fsnotify_file(file, FS_ACCESS);
 311 }
 312
 313 /*
 314  * fsnotify_modify - file was modified
 315  */
 316 static inline void fsnotify_modify(struct file *file)
 317 {
 318         fsnotify_file(file, FS_MODIFY);
 319 }
 320
 321 /*
 322  * fsnotify_open - file was opened
 323  */
 324 static inline void fsnotify_open(struct file *file)
 325 {
 326         __u32 mask = FS_OPEN;
 327
 328         if (file->f_flags & __FMODE_EXEC)
 329                 mask |= FS_OPEN_EXEC;
 330
 331         fsnotify_file(file, mask);
 332 }
 333
 334 /*
 335  * fsnotify_close - file was closed
 336  */
 337 static inline void fsnotify_close(struct file *file)
 338 {
 339         __u32 mask = (file->f_mode & FMODE_WRITE) ? FS_CLOSE_WRITE :
 340                                                     FS_CLOSE_NOWRITE;
 341
 342         fsnotify_file(file, mask);
 343 }
 344
 345 /*
 346  * fsnotify_xattr - extended attributes were changed
 347  */
 348 static inline void fsnotify_xattr(struct dentry *dentry)
 349 {
 350         fsnotify_dentry(dentry, FS_ATTRIB);
 351 }
 352
 353 /*
 354  * fsnotify_change - notify_change event.  file was modified and/or metadata
 355  * was changed.
 356  */
 357 static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
 358 {
 359         __u32 mask = 0;
 360
 361         if (ia_valid & ATTR_UID)
 362                 mask |= FS_ATTRIB;
 363         if (ia_valid & ATTR_GID)
 364                 mask |= FS_ATTRIB;
 365         if (ia_valid & ATTR_SIZE)
 366                 mask |= FS_MODIFY;
 367
 368         /* both times implies a utime(s) call */
 369         if ((ia_valid & (ATTR_ATIME | ATTR_MTIME)) == (ATTR_ATIME | ATTR_MTIME))
 370                 mask |= FS_ATTRIB;
 371         else if (ia_valid & ATTR_ATIME)
 372                 mask |= FS_ACCESS;
 373         else if (ia_valid & ATTR_MTIME)
 374                 mask |= FS_MODIFY;
 375
 376         if (ia_valid & ATTR_MODE)
 377                 mask |= FS_ATTRIB;
 378
 379         if (mask)
 380                 fsnotify_dentry(dentry, mask);
 381 }
 382
 383 static inline int fsnotify_sb_error(struct super_block *sb, struct inode *inode,
 384                                     int error)
 385 {
 386         struct fs_error_report report = {
 387                 .error = error,
 388                 .inode = inode,
 389                 .sb = sb,
 390         };
 391
 392         return fsnotify(FS_ERROR, &report, FSNOTIFY_EVENT_ERROR,
 393                         NULL, NULL, NULL, 0);
 394 }
 395
 396 #endif  /* _LINUX_FS_NOTIFY_H */