1 /* 2 * Filesystem access notification for Linux 3 * 4 * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> 5 */ 6 7 #ifndef __LINUX_FSNOTIFY_BACKEND_H 8 #define __LINUX_FSNOTIFY_BACKEND_H 9 10 #ifdef __KERNEL__ 11 12 #include <linux/idr.h> /* inotify uses this */ 13 #include <linux/fs.h> /* struct inode */ 14 #include <linux/list.h> 15 #include <linux/path.h> /* struct path */ 16 #include <linux/spinlock.h> 17 #include <linux/types.h> 18 #include <linux/atomic.h> 19 20 /* 21 * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily 22 * convert between them. dnotify only needs conversion at watch creation 23 * so no perf loss there. fanotify isn't defined yet, so it can use the 24 * wholes if it needs more events. 25 */ 26 #define FS_ACCESS 0x00000001 /* File was accessed */ 27 #define FS_MODIFY 0x00000002 /* File was modified */ 28 #define FS_ATTRIB 0x00000004 /* Metadata changed */ 29 #define FS_CLOSE_WRITE 0x00000008 /* Writtable file was closed */ 30 #define FS_CLOSE_NOWRITE 0x00000010 /* Unwrittable file closed */ 31 #define FS_OPEN 0x00000020 /* File was opened */ 32 #define FS_MOVED_FROM 0x00000040 /* File was moved from X */ 33 #define FS_MOVED_TO 0x00000080 /* File was moved to Y */ 34 #define FS_CREATE 0x00000100 /* Subfile was created */ 35 #define FS_DELETE 0x00000200 /* Subfile was deleted */ 36 #define FS_DELETE_SELF 0x00000400 /* Self was deleted */ 37 #define FS_MOVE_SELF 0x00000800 /* Self was moved */ 38 39 #define FS_UNMOUNT 0x00002000 /* inode on umount fs */ 40 #define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */ 41 #define FS_IN_IGNORED 0x00008000 /* last inotify event here */ 42 43 #define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */ 44 #define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */ 45 46 #define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */ 47 #define FS_ISDIR 0x40000000 /* event occurred against dir */ 48 #define FS_IN_ONESHOT 0x80000000 /* only send event once */ 49 50 #define FS_DN_RENAME 0x10000000 /* file renamed */ 51 #define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */ 52 53 /* This inode cares about things that happen to its children. Always set for 54 * dnotify and inotify. */ 55 #define FS_EVENT_ON_CHILD 0x08000000 56 57 /* This is a list of all events that may get sent to a parernt based on fs event 58 * happening to inodes inside that directory */ 59 #define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\ 60 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\ 61 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\ 62 FS_DELETE | FS_OPEN_PERM | FS_ACCESS_PERM) 63 64 #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO) 65 66 #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM) 67 68 #define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \ 69 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \ 70 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \ 71 FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \ 72 FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \ 73 FS_OPEN_PERM | FS_ACCESS_PERM | FS_EXCL_UNLINK | \ 74 FS_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \ 75 FS_DN_MULTISHOT | FS_EVENT_ON_CHILD) 76 77 struct fsnotify_group; 78 struct fsnotify_event; 79 struct fsnotify_mark; 80 struct fsnotify_event_private_data; 81 struct fsnotify_fname; 82 83 /* 84 * Each group much define these ops. The fsnotify infrastructure will call 85 * these operations for each relevant group. 86 * 87 * handle_event - main call for a group to handle an fs event 88 * free_group_priv - called when a group refcnt hits 0 to clean up the private union 89 * freeing_mark - called when a mark is being destroyed for some reason. The group 90 * MUST be holding a reference on each mark and that reference must be 91 * dropped in this function. inotify uses this function to send 92 * userspace messages that marks have been removed. 93 */ 94 struct fsnotify_ops { 95 int (*handle_event)(struct fsnotify_group *group, 96 struct inode *inode, 97 struct fsnotify_mark *inode_mark, 98 struct fsnotify_mark *vfsmount_mark, 99 u32 mask, void *data, int data_type, 100 const unsigned char *file_name, u32 cookie); 101 void (*free_group_priv)(struct fsnotify_group *group); 102 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group); 103 void (*free_event)(struct fsnotify_event *event); 104 }; 105 106 /* 107 * all of the information about the original object we want to now send to 108 * a group. If you want to carry more info from the accessing task to the 109 * listener this structure is where you need to be adding fields. 110 */ 111 struct fsnotify_event { 112 struct list_head list; 113 /* inode may ONLY be dereferenced during handle_event(). */ 114 struct inode *inode; /* either the inode the event happened to or its parent */ 115 u32 mask; /* the type of access, bitwise OR for FS_* event types */ 116 }; 117 118 /* 119 * A group is a "thing" that wants to receive notification about filesystem 120 * events. The mask holds the subset of event types this group cares about. 121 * refcnt on a group is up to the implementor and at any moment if it goes 0 122 * everything will be cleaned up. 123 */ 124 struct fsnotify_group { 125 /* 126 * How the refcnt is used is up to each group. When the refcnt hits 0 127 * fsnotify will clean up all of the resources associated with this group. 128 * As an example, the dnotify group will always have a refcnt=1 and that 129 * will never change. Inotify, on the other hand, has a group per 130 * inotify_init() and the refcnt will hit 0 only when that fd has been 131 * closed. 132 */ 133 atomic_t refcnt; /* things with interest in this group */ 134 135 const struct fsnotify_ops *ops; /* how this group handles things */ 136 137 /* needed to send notification to userspace */ 138 struct mutex notification_mutex; /* protect the notification_list */ 139 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */ 140 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */ 141 unsigned int q_len; /* events on the queue */ 142 unsigned int max_events; /* maximum events allowed on the list */ 143 /* 144 * Valid fsnotify group priorities. Events are send in order from highest 145 * priority to lowest priority. We default to the lowest priority. 146 */ 147 #define FS_PRIO_0 0 /* normal notifiers, no permissions */ 148 #define FS_PRIO_1 1 /* fanotify content based access control */ 149 #define FS_PRIO_2 2 /* fanotify pre-content access */ 150 unsigned int priority; 151 152 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */ 153 struct mutex mark_mutex; /* protect marks_list */ 154 atomic_t num_marks; /* 1 for each mark and 1 for not being 155 * past the point of no return when freeing 156 * a group */ 157 struct list_head marks_list; /* all inode marks for this group */ 158 159 struct fasync_struct *fsn_fa; /* async notification */ 160 161 struct fsnotify_event *overflow_event; /* Event we queue when the 162 * notification list is too 163 * full */ 164 165 /* groups can define private fields here or use the void *private */ 166 union { 167 void *private; 168 #ifdef CONFIG_INOTIFY_USER 169 struct inotify_group_private_data { 170 spinlock_t idr_lock; 171 struct idr idr; 172 struct user_struct *user; 173 } inotify_data; 174 #endif 175 #ifdef CONFIG_FANOTIFY 176 struct fanotify_group_private_data { 177 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 178 /* allows a group to block waiting for a userspace response */ 179 spinlock_t access_lock; 180 struct list_head access_list; 181 wait_queue_head_t access_waitq; 182 atomic_t bypass_perm; 183 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */ 184 int f_flags; 185 unsigned int max_marks; 186 struct user_struct *user; 187 } fanotify_data; 188 #endif /* CONFIG_FANOTIFY */ 189 }; 190 }; 191 192 /* when calling fsnotify tell it if the data is a path or inode */ 193 #define FSNOTIFY_EVENT_NONE 0 194 #define FSNOTIFY_EVENT_PATH 1 195 #define FSNOTIFY_EVENT_INODE 2 196 197 /* 198 * A mark is simply an object attached to an in core inode which allows an 199 * fsnotify listener to indicate they are either no longer interested in events 200 * of a type matching mask or only interested in those events. 201 * 202 * These are flushed when an inode is evicted from core and may be flushed 203 * when the inode is modified (as seen by fsnotify_access). Some fsnotify 204 * users (such as dnotify) will flush these when the open fd is closed and not 205 * at inode eviction or modification. 206 * 207 * Text in brackets is showing the lock(s) protecting modifications of a 208 * particular entry. obj_lock means either inode->i_lock or 209 * mnt->mnt_root->d_lock depending on the mark type. 210 */ 211 struct fsnotify_mark { 212 /* Mask this mark is for [mark->lock, group->mark_mutex] */ 213 __u32 mask; 214 /* We hold one for presence in g_list. Also one ref for each 'thing' 215 * in kernel that found and may be using this mark. */ 216 atomic_t refcnt; 217 /* Group this mark is for. Set on mark creation, stable until last ref 218 * is dropped */ 219 struct fsnotify_group *group; 220 /* List of marks by group->i_fsnotify_marks. Also reused for queueing 221 * mark into destroy_list when it's waiting for the end of SRCU period 222 * before it can be freed. [group->mark_mutex] */ 223 struct list_head g_list; 224 /* Protects inode / mnt pointers, flags, masks */ 225 spinlock_t lock; 226 /* List of marks for inode / vfsmount [obj_lock] */ 227 struct hlist_node obj_list; 228 union { /* Object pointer [mark->lock, group->mark_mutex] */ 229 struct inode *inode; /* inode this mark is associated with */ 230 struct vfsmount *mnt; /* vfsmount this mark is associated with */ 231 }; 232 /* Events types to ignore [mark->lock, group->mark_mutex] */ 233 __u32 ignored_mask; 234 #define FSNOTIFY_MARK_FLAG_INODE 0x01 235 #define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02 236 #define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04 237 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08 238 #define FSNOTIFY_MARK_FLAG_ALIVE 0x10 239 #define FSNOTIFY_MARK_FLAG_ATTACHED 0x20 240 unsigned int flags; /* flags [mark->lock] */ 241 void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */ 242 }; 243 244 #ifdef CONFIG_FSNOTIFY 245 246 /* called from the vfs helpers */ 247 248 /* main fsnotify call to send events */ 249 extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 250 const unsigned char *name, u32 cookie); 251 extern int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask); 252 extern void __fsnotify_inode_delete(struct inode *inode); 253 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt); 254 extern u32 fsnotify_get_cookie(void); 255 256 static inline int fsnotify_inode_watches_children(struct inode *inode) 257 { 258 /* FS_EVENT_ON_CHILD is set if the inode may care */ 259 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD)) 260 return 0; 261 /* this inode might care about child events, does it care about the 262 * specific set of events that can happen on a child? */ 263 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD; 264 } 265 266 /* 267 * Update the dentry with a flag indicating the interest of its parent to receive 268 * filesystem events when those events happens to this dentry->d_inode. 269 */ 270 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) 271 { 272 struct dentry *parent; 273 274 assert_spin_locked(&dentry->d_lock); 275 276 /* 277 * Serialisation of setting PARENT_WATCHED on the dentries is provided 278 * by d_lock. If inotify_inode_watched changes after we have taken 279 * d_lock, the following __fsnotify_update_child_dentry_flags call will 280 * find our entry, so it will spin until we complete here, and update 281 * us with the new state. 282 */ 283 parent = dentry->d_parent; 284 if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode)) 285 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; 286 else 287 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; 288 } 289 290 /* 291 * fsnotify_d_instantiate - instantiate a dentry for inode 292 */ 293 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) 294 { 295 if (!inode) 296 return; 297 298 spin_lock(&dentry->d_lock); 299 __fsnotify_update_dcache_flags(dentry); 300 spin_unlock(&dentry->d_lock); 301 } 302 303 /* called from fsnotify listeners, such as fanotify or dnotify */ 304 305 /* create a new group */ 306 extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops); 307 /* get reference to a group */ 308 extern void fsnotify_get_group(struct fsnotify_group *group); 309 /* drop reference on a group from fsnotify_alloc_group */ 310 extern void fsnotify_put_group(struct fsnotify_group *group); 311 /* destroy group */ 312 extern void fsnotify_destroy_group(struct fsnotify_group *group); 313 /* fasync handler function */ 314 extern int fsnotify_fasync(int fd, struct file *file, int on); 315 /* Free event from memory */ 316 extern void fsnotify_destroy_event(struct fsnotify_group *group, 317 struct fsnotify_event *event); 318 /* attach the event to the group notification queue */ 319 extern int fsnotify_add_event(struct fsnotify_group *group, 320 struct fsnotify_event *event, 321 int (*merge)(struct list_head *, 322 struct fsnotify_event *)); 323 /* Remove passed event from groups notification queue */ 324 extern void fsnotify_remove_event(struct fsnotify_group *group, struct fsnotify_event *event); 325 /* true if the group notification queue is empty */ 326 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group); 327 /* return, but do not dequeue the first event on the notification queue */ 328 extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group); 329 /* return AND dequeue the first event on the notification queue */ 330 extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group); 331 332 /* functions used to manipulate the marks attached to inodes */ 333 334 /* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */ 335 extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt); 336 /* run all marks associated with an inode and update inode->i_fsnotify_mask */ 337 extern void fsnotify_recalc_inode_mask(struct inode *inode); 338 extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark)); 339 /* find (and take a reference) to a mark associated with group and inode */ 340 extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode); 341 /* find (and take a reference) to a mark associated with group and vfsmount */ 342 extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt); 343 /* copy the values from old into new */ 344 extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old); 345 /* set the ignored_mask of a mark */ 346 extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask); 347 /* set the mask of a mark (might pin the object into memory */ 348 extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask); 349 /* attach the mark to both the group and the inode */ 350 extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group, 351 struct inode *inode, struct vfsmount *mnt, int allow_dups); 352 extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct fsnotify_group *group, 353 struct inode *inode, struct vfsmount *mnt, int allow_dups); 354 /* given a group and a mark, flag mark to be freed when all references are dropped */ 355 extern void fsnotify_destroy_mark(struct fsnotify_mark *mark, 356 struct fsnotify_group *group); 357 /* detach mark from inode / mount list, group list, drop inode reference */ 358 extern void fsnotify_detach_mark(struct fsnotify_mark *mark); 359 /* free mark */ 360 extern void fsnotify_free_mark(struct fsnotify_mark *mark); 361 /* run all the marks in a group, and clear all of the vfsmount marks */ 362 extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group); 363 /* run all the marks in a group, and clear all of the inode marks */ 364 extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group); 365 /* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/ 366 extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags); 367 /* run all the marks in a group, and flag them to be freed */ 368 extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group); 369 extern void fsnotify_get_mark(struct fsnotify_mark *mark); 370 extern void fsnotify_put_mark(struct fsnotify_mark *mark); 371 extern void fsnotify_unmount_inodes(struct super_block *sb); 372 373 /* put here because inotify does some weird stuff when destroying watches */ 374 extern void fsnotify_init_event(struct fsnotify_event *event, 375 struct inode *to_tell, u32 mask); 376 377 #else 378 379 static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 380 const unsigned char *name, u32 cookie) 381 { 382 return 0; 383 } 384 385 static inline int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) 386 { 387 return 0; 388 } 389 390 static inline void __fsnotify_inode_delete(struct inode *inode) 391 {} 392 393 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt) 394 {} 395 396 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) 397 {} 398 399 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) 400 {} 401 402 static inline u32 fsnotify_get_cookie(void) 403 { 404 return 0; 405 } 406 407 static inline void fsnotify_unmount_inodes(struct super_block *sb) 408 {} 409 410 #endif /* CONFIG_FSNOTIFY */ 411 412 #endif /* __KERNEL __ */ 413 414 #endif /* __LINUX_FSNOTIFY_BACKEND_H */ 415