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 /* Are there any inode/mount/sb objects watched with priority prio or above? */
  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? */
  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  */
  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
  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
  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. */
  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  */
 106 static inline void fsnotify_dentry(struct dentry *dentry, __u32 mask)
 107 {
 108         fsnotify_parent(dentry, mask, dentry, FSNOTIFY_EVENT_DENTRY);
 109 }
 110
 111 static inline int fsnotify_file(struct file *file, __u32 mask)
 112 {
 113         const struct path *path;
 114
 115         /*
 116          * FMODE_NONOTIFY are fds generated by fanotify itself which should not
 117          * generate new events. We also don't want to generate events for
 118          * FMODE_PATH fds (involves open & close events) as they are just
 119          * handle creation / destruction events and not "real" file events.
 120          */
 121         if (file->f_mode & (FMODE_NONOTIFY | FMODE_PATH))
 122                 return 0;
 123
 124         path = &file->f_path;
 125         /* Permission events require group prio >= FSNOTIFY_PRIO_CONTENT */
 126         if (mask & ALL_FSNOTIFY_PERM_EVENTS &&
 127             !fsnotify_sb_has_priority_watchers(path->dentry->d_sb,
 128                                                FSNOTIFY_PRIO_CONTENT))
 129                 return 0;
 130
 131         return fsnotify_parent(path->dentry, mask, path, FSNOTIFY_EVENT_PATH);
 132 }
 133
 134 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 135 /*
 136  * fsnotify_file_area_perm - permission hook before access to file range
 137  */
 138 static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
 139                                           const loff_t *ppos, size_t count)
 140 {
 141         __u32 fsnotify_mask = FS_ACCESS_PERM;
 142
 143         /*
 144          * filesystem may be modified in the context of permission events
 145          * (e.g. by HSM filling a file on access), so sb freeze protection
 146          * must not be held.
 147          */
 148         lockdep_assert_once(file_write_not_started(file));
 149
 150         if (!(perm_mask & MAY_READ))
 151                 return 0;
 152
 153         return fsnotify_file(file, fsnotify_mask);
 154 }
 155
 156 /*
 157  * fsnotify_file_perm - permission hook before file access
 158  */
 159 static inline int fsnotify_file_perm(struct file *file, int perm_mask)
 160 {
 161         return fsnotify_file_area_perm(file, perm_mask, NULL, 0);
 162 }
 163
 164 /*
 165  * fsnotify_open_perm - permission hook before file open
 166  */
 167 static inline int fsnotify_open_perm(struct file *file)
 168 {
 169         int ret;
 170
 171         if (file->f_flags & __FMODE_EXEC) {
 172                 ret = fsnotify_file(file, FS_OPEN_EXEC_PERM);
 173                 if (ret)
 174                         return ret;
 175         }
 176
 177         return fsnotify_file(file, FS_OPEN_PERM);
 178 }
 179
 180 #else
 181 static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
 182                                           const loff_t *ppos, size_t count)
 183 {
 184         return 0;
 185 }
 186
 187 static inline int fsnotify_file_perm(struct file *file, int perm_mask)
 188 {
 189         return 0;
 190 }
 191
 192 static inline int fsnotify_open_perm(struct file *file)
 193 {
 194         return 0;
 195 }
 196 #endif
 197
 198 /*
 199  * fsnotify_link_count - inode's link count changed
 200  */
 201 static inline void fsnotify_link_count(struct inode *inode)
 202 {
 203         fsnotify_inode(inode, FS_ATTRIB);
 204 }
 205
 206 /*
 207  * fsnotify_move - file old_name at old_dir was moved to new_name at new_dir
 208  */
 209 static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
 210                                  const struct qstr *old_name,
 211                                  int isdir, struct inode *target,
 212                                  struct dentry *moved)
 213 {
 214         struct inode *source = moved->d_inode;
 215         u32 fs_cookie = fsnotify_get_cookie();
 216         __u32 old_dir_mask = FS_MOVED_FROM;
 217         __u32 new_dir_mask = FS_MOVED_TO;
 218         __u32 rename_mask = FS_RENAME;
 219         const struct qstr *new_name = &moved->d_name;
 220
 221         if (isdir) {
 222                 old_dir_mask |= FS_ISDIR;
 223                 new_dir_mask |= FS_ISDIR;
 224                 rename_mask |= FS_ISDIR;
 225         }
 226
 227         /* Event with information about both old and new parent+name */
 228         fsnotify_name(rename_mask, moved, FSNOTIFY_EVENT_DENTRY,
 229                       old_dir, old_name, 0);
 230
 231         fsnotify_name(old_dir_mask, source, FSNOTIFY_EVENT_INODE,
 232                       old_dir, old_name, fs_cookie);
 233         fsnotify_name(new_dir_mask, source, FSNOTIFY_EVENT_INODE,
 234                       new_dir, new_name, fs_cookie);
 235
 236         if (target)
 237                 fsnotify_link_count(target);
 238         fsnotify_inode(source, FS_MOVE_SELF);
 239         audit_inode_child(new_dir, moved, AUDIT_TYPE_CHILD_CREATE);
 240 }
 241
 242 /*
 243  * fsnotify_inode_delete - and inode is being evicted from cache, clean up is needed
 244  */
 245 static inline void fsnotify_inode_delete(struct inode *inode)
 246 {
 247         __fsnotify_inode_delete(inode);
 248 }
 249
 250 /*
 251  * fsnotify_vfsmount_delete - a vfsmount is being destroyed, clean up is needed
 252  */
 253 static inline void fsnotify_vfsmount_delete(struct vfsmount *mnt)
 254 {
 255         __fsnotify_vfsmount_delete(mnt);
 256 }
 257
 258 /*
 259  * fsnotify_inoderemove - an inode is going away
 260  */
 261 static inline void fsnotify_inoderemove(struct inode *inode)
 262 {
 263         fsnotify_inode(inode, FS_DELETE_SELF);
 264         __fsnotify_inode_delete(inode);
 265 }
 266
 267 /*
 268  * fsnotify_create - 'name' was linked in
 269  *
 270  * Caller must make sure that dentry->d_name is stable.
 271  * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
 272  * ->d_inode later
 273  */
 274 static inline void fsnotify_create(struct inode *dir, struct dentry *dentry)
 275 {
 276         audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);
 277
 278         fsnotify_dirent(dir, dentry, FS_CREATE);
 279 }
 280
 281 /*
 282  * fsnotify_link - new hardlink in 'inode' directory
 283  *
 284  * Caller must make sure that new_dentry->d_name is stable.
 285  * Note: We have to pass also the linked inode ptr as some filesystems leave
 286  *   new_dentry->d_inode NULL and instantiate inode pointer later
 287  */
 288 static inline void fsnotify_link(struct inode *dir, struct inode *inode,
 289                                  struct dentry *new_dentry)
 290 {
 291         fsnotify_link_count(inode);
 292         audit_inode_child(dir, new_dentry, AUDIT_TYPE_CHILD_CREATE);
 293
 294         fsnotify_name(FS_CREATE, inode, FSNOTIFY_EVENT_INODE,
 295                       dir, &new_dentry->d_name, 0);
 296 }
 297
 298 /*
 299  * fsnotify_delete - @dentry was unlinked and unhashed
 300  *
 301  * Caller must make sure that dentry->d_name is stable.
 302  *
 303  * Note: unlike fsnotify_unlink(), we have to pass also the unlinked inode
 304  * as this may be called after d_delete() and old_dentry may be negative.
 305  */
 306 static inline void fsnotify_delete(struct inode *dir, struct inode *inode,
 307                                    struct dentry *dentry)
 308 {
 309         __u32 mask = FS_DELETE;
 310
 311         if (S_ISDIR(inode->i_mode))
 312                 mask |= FS_ISDIR;
 313
 314         fsnotify_name(mask, inode, FSNOTIFY_EVENT_INODE, dir, &dentry->d_name,
 315                       0);
 316 }
 317
 318 /**
 319  * d_delete_notify - delete a dentry and call fsnotify_delete()
 320  * @dentry: The dentry to delete
 321  *
 322  * This helper is used to guaranty that the unlinked inode cannot be found
 323  * by lookup of this name after fsnotify_delete() event has been delivered.
 324  */
 325 static inline void d_delete_notify(struct inode *dir, struct dentry *dentry)
 326 {
 327         struct inode *inode = d_inode(dentry);
 328
 329         ihold(inode);
 330         d_delete(dentry);
 331         fsnotify_delete(dir, inode, dentry);
 332         iput(inode);
 333 }
 334
 335 /*
 336  * fsnotify_unlink - 'name' was unlinked
 337  *
 338  * Caller must make sure that dentry->d_name is stable.
 339  */
 340 static inline void fsnotify_unlink(struct inode *dir, struct dentry *dentry)
 341 {
 342         if (WARN_ON_ONCE(d_is_negative(dentry)))
 343                 return;
 344
 345         fsnotify_delete(dir, d_inode(dentry), dentry);
 346 }
 347
 348 /*
 349  * fsnotify_mkdir - directory 'name' was created
 350  *
 351  * Caller must make sure that dentry->d_name is stable.
 352  * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
 353  * ->d_inode later
 354  */
 355 static inline void fsnotify_mkdir(struct inode *dir, struct dentry *dentry)
 356 {
 357         audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);
 358
 359         fsnotify_dirent(dir, dentry, FS_CREATE | FS_ISDIR);
 360 }
 361
 362 /*
 363  * fsnotify_rmdir - directory 'name' was removed
 364  *
 365  * Caller must make sure that dentry->d_name is stable.
 366  */
 367 static inline void fsnotify_rmdir(struct inode *dir, struct dentry *dentry)
 368 {
 369         if (WARN_ON_ONCE(d_is_negative(dentry)))
 370                 return;
 371
 372         fsnotify_delete(dir, d_inode(dentry), dentry);
 373 }
 374
 375 /*
 376  * fsnotify_access - file was read
 377  */
 378 static inline void fsnotify_access(struct file *file)
 379 {
 380         fsnotify_file(file, FS_ACCESS);
 381 }
 382
 383 /*
 384  * fsnotify_modify - file was modified
 385  */
 386 static inline void fsnotify_modify(struct file *file)
 387 {
 388         fsnotify_file(file, FS_MODIFY);
 389 }
 390
 391 /*
 392  * fsnotify_open - file was opened
 393  */
 394 static inline void fsnotify_open(struct file *file)
 395 {
 396         __u32 mask = FS_OPEN;
 397
 398         if (file->f_flags & __FMODE_EXEC)
 399                 mask |= FS_OPEN_EXEC;
 400
 401         fsnotify_file(file, mask);
 402 }
 403
 404 /*
 405  * fsnotify_close - file was closed
 406  */
 407 static inline void fsnotify_close(struct file *file)
 408 {
 409         __u32 mask = (file->f_mode & FMODE_WRITE) ? FS_CLOSE_WRITE :
 410                                                     FS_CLOSE_NOWRITE;
 411
 412         fsnotify_file(file, mask);
 413 }
 414
 415 /*
 416  * fsnotify_xattr - extended attributes were changed
 417  */
 418 static inline void fsnotify_xattr(struct dentry *dentry)
 419 {
 420         fsnotify_dentry(dentry, FS_ATTRIB);
 421 }
 422
 423 /*
 424  * fsnotify_change - notify_change event.  file was modified and/or metadata
 425  * was changed.
 426  */
 427 static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
 428 {
 429         __u32 mask = 0;
 430
 431         if (ia_valid & ATTR_UID)
 432                 mask |= FS_ATTRIB;
 433         if (ia_valid & ATTR_GID)
 434                 mask |= FS_ATTRIB;
 435         if (ia_valid & ATTR_SIZE)
 436                 mask |= FS_MODIFY;
 437
 438         /* both times implies a utime(s) call */
 439         if ((ia_valid & (ATTR_ATIME | ATTR_MTIME)) == (ATTR_ATIME | ATTR_MTIME))
 440                 mask |= FS_ATTRIB;
 441         else if (ia_valid & ATTR_ATIME)
 442                 mask |= FS_ACCESS;
 443         else if (ia_valid & ATTR_MTIME)
 444                 mask |= FS_MODIFY;
 445
 446         if (ia_valid & ATTR_MODE)
 447                 mask |= FS_ATTRIB;
 448
 449         if (mask)
 450                 fsnotify_dentry(dentry, mask);
 451 }
 452
 453 static inline int fsnotify_sb_error(struct super_block *sb, struct inode *inode,
 454                                     int error)
 455 {
 456         struct fs_error_report report = {
 457                 .error = error,
 458                 .inode = inode,
 459                 .sb = sb,
 460         };
 461
 462         return fsnotify(FS_ERROR, &report, FSNOTIFY_EVENT_ERROR,
 463                         NULL, NULL, NULL, 0);
 464 }
 465
 466 #endif  /* _LINUX_FS_NOTIFY_H */