1 /* 2 * Filesystem access notification for Linux 3 * 4 * Copyright (C) 2008 Red Hat, Inc., Eric Paris <[email protected]> 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 #include <linux/user_namespace.h> 20 21 /* 22 * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily 23 * convert between them. dnotify only needs conversion at watch creation 24 * so no perf loss there. fanotify isn't defined yet, so it can use the 25 * wholes if it needs more events. 26 */ 27 #define FS_ACCESS 0x00000001 /* File was accessed */ 28 #define FS_MODIFY 0x00000002 /* File was modified */ 29 #define FS_ATTRIB 0x00000004 /* Metadata changed */ 30 #define FS_CLOSE_WRITE 0x00000008 /* Writtable file was closed */ 31 #define FS_CLOSE_NOWRITE 0x00000010 /* Unwrittable file closed */ 32 #define FS_OPEN 0x00000020 /* File was opened */ 33 #define FS_MOVED_FROM 0x00000040 /* File was moved from X */ 34 #define FS_MOVED_TO 0x00000080 /* File was moved to Y */ 35 #define FS_CREATE 0x00000100 /* Subfile was created */ 36 #define FS_DELETE 0x00000200 /* Subfile was deleted */ 37 #define FS_DELETE_SELF 0x00000400 /* Self was deleted */ 38 #define FS_MOVE_SELF 0x00000800 /* Self was moved */ 39 40 #define FS_UNMOUNT 0x00002000 /* inode on umount fs */ 41 #define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */ 42 #define FS_IN_IGNORED 0x00008000 /* last inotify event here */ 43 44 #define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */ 45 #define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */ 46 47 #define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */ 48 #define FS_ISDIR 0x40000000 /* event occurred against dir */ 49 #define FS_IN_ONESHOT 0x80000000 /* only send event once */ 50 51 #define FS_DN_RENAME 0x10000000 /* file renamed */ 52 #define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */ 53 54 /* This inode cares about things that happen to its children. Always set for 55 * dnotify and inotify. */ 56 #define FS_EVENT_ON_CHILD 0x08000000 57 58 /* This is a list of all events that may get sent to a parernt based on fs event 59 * happening to inodes inside that directory */ 60 #define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\ 61 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\ 62 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\ 63 FS_DELETE | FS_OPEN_PERM | FS_ACCESS_PERM) 64 65 #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO) 66 67 #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM) 68 69 #define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \ 70 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \ 71 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \ 72 FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \ 73 FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \ 74 FS_OPEN_PERM | FS_ACCESS_PERM | FS_EXCL_UNLINK | \ 75 FS_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \ 76 FS_DN_MULTISHOT | FS_EVENT_ON_CHILD) 77 78 struct fsnotify_group; 79 struct fsnotify_event; 80 struct fsnotify_mark; 81 struct fsnotify_event_private_data; 82 struct fsnotify_fname; 83 84 /* 85 * Each group much define these ops. The fsnotify infrastructure will call 86 * these operations for each relevant group. 87 * 88 * handle_event - main call for a group to handle an fs event 89 * free_group_priv - called when a group refcnt hits 0 to clean up the private union 90 * freeing_mark - called when a mark is being destroyed for some reason. The group 91 * MUST be holding a reference on each mark and that reference must be 92 * dropped in this function. inotify uses this function to send 93 * userspace messages that marks have been removed. 94 */ 95 struct fsnotify_ops { 96 int (*handle_event)(struct fsnotify_group *group, 97 struct inode *inode, 98 struct fsnotify_mark *inode_mark, 99 struct fsnotify_mark *vfsmount_mark, 100 u32 mask, const void *data, int data_type, 101 const unsigned char *file_name, u32 cookie); 102 void (*free_group_priv)(struct fsnotify_group *group); 103 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group); 104 void (*free_event)(struct fsnotify_event *event); 105 }; 106 107 /* 108 * all of the information about the original object we want to now send to 109 * a group. If you want to carry more info from the accessing task to the 110 * listener this structure is where you need to be adding fields. 111 */ 112 struct fsnotify_event { 113 struct list_head list; 114 /* inode may ONLY be dereferenced during handle_event(). */ 115 struct inode *inode; /* either the inode the event happened to or its parent */ 116 u32 mask; /* the type of access, bitwise OR for FS_* event types */ 117 }; 118 119 /* 120 * A group is a "thing" that wants to receive notification about filesystem 121 * events. The mask holds the subset of event types this group cares about. 122 * refcnt on a group is up to the implementor and at any moment if it goes 0 123 * everything will be cleaned up. 124 */ 125 struct fsnotify_group { 126 /* 127 * How the refcnt is used is up to each group. When the refcnt hits 0 128 * fsnotify will clean up all of the resources associated with this group. 129 * As an example, the dnotify group will always have a refcnt=1 and that 130 * will never change. Inotify, on the other hand, has a group per 131 * inotify_init() and the refcnt will hit 0 only when that fd has been 132 * closed. 133 */ 134 atomic_t refcnt; /* things with interest in this group */ 135 136 const struct fsnotify_ops *ops; /* how this group handles things */ 137 138 /* needed to send notification to userspace */ 139 spinlock_t notification_lock; /* protect the notification_list */ 140 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */ 141 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */ 142 unsigned int q_len; /* events on the queue */ 143 unsigned int max_events; /* maximum events allowed on the list */ 144 /* 145 * Valid fsnotify group priorities. Events are send in order from highest 146 * priority to lowest priority. We default to the lowest priority. 147 */ 148 #define FS_PRIO_0 0 /* normal notifiers, no permissions */ 149 #define FS_PRIO_1 1 /* fanotify content based access control */ 150 #define FS_PRIO_2 2 /* fanotify pre-content access */ 151 unsigned int priority; 152 bool shutdown; /* group is being shut down, don't queue more events */ 153 154 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */ 155 struct mutex mark_mutex; /* protect marks_list */ 156 atomic_t num_marks; /* 1 for each mark and 1 for not being 157 * past the point of no return when freeing 158 * a group */ 159 struct list_head marks_list; /* all inode marks for this group */ 160 161 struct fasync_struct *fsn_fa; /* async notification */ 162 163 struct fsnotify_event *overflow_event; /* Event we queue when the 164 * notification list is too 165 * full */ 166 167 /* groups can define private fields here or use the void *private */ 168 union { 169 void *private; 170 #ifdef CONFIG_INOTIFY_USER 171 struct inotify_group_private_data { 172 spinlock_t idr_lock; 173 struct idr idr; 174 struct ucounts *ucounts; 175 } inotify_data; 176 #endif 177 #ifdef CONFIG_FANOTIFY 178 struct fanotify_group_private_data { 179 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 180 /* allows a group to block waiting for a userspace response */ 181 struct list_head access_list; 182 wait_queue_head_t access_waitq; 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, const void *data, int data_is, 250 const unsigned char *name, u32 cookie); 251 extern int __fsnotify_parent(const 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_flags(struct dentry *dentry) 271 { 272 assert_spin_locked(&dentry->d_lock); 273 274 /* 275 * Serialisation of setting PARENT_WATCHED on the dentries is provided 276 * by d_lock. If inotify_inode_watched changes after we have taken 277 * d_lock, the following __fsnotify_update_child_dentry_flags call will 278 * find our entry, so it will spin until we complete here, and update 279 * us with the new state. 280 */ 281 if (fsnotify_inode_watches_children(dentry->d_parent->d_inode)) 282 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; 283 else 284 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; 285 } 286 287 /* called from fsnotify listeners, such as fanotify or dnotify */ 288 289 /* create a new group */ 290 extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops); 291 /* get reference to a group */ 292 extern void fsnotify_get_group(struct fsnotify_group *group); 293 /* drop reference on a group from fsnotify_alloc_group */ 294 extern void fsnotify_put_group(struct fsnotify_group *group); 295 /* group destruction begins, stop queuing new events */ 296 extern void fsnotify_group_stop_queueing(struct fsnotify_group *group); 297 /* destroy group */ 298 extern void fsnotify_destroy_group(struct fsnotify_group *group); 299 /* fasync handler function */ 300 extern int fsnotify_fasync(int fd, struct file *file, int on); 301 /* Free event from memory */ 302 extern void fsnotify_destroy_event(struct fsnotify_group *group, 303 struct fsnotify_event *event); 304 /* attach the event to the group notification queue */ 305 extern int fsnotify_add_event(struct fsnotify_group *group, 306 struct fsnotify_event *event, 307 int (*merge)(struct list_head *, 308 struct fsnotify_event *)); 309 /* true if the group notification queue is empty */ 310 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group); 311 /* return, but do not dequeue the first event on the notification queue */ 312 extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group); 313 /* return AND dequeue the first event on the notification queue */ 314 extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group); 315 316 /* functions used to manipulate the marks attached to inodes */ 317 318 /* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */ 319 extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt); 320 /* run all marks associated with an inode and update inode->i_fsnotify_mask */ 321 extern void fsnotify_recalc_inode_mask(struct inode *inode); 322 extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark)); 323 /* find (and take a reference) to a mark associated with group and inode */ 324 extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode); 325 /* find (and take a reference) to a mark associated with group and vfsmount */ 326 extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt); 327 /* set the ignored_mask of a mark */ 328 extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask); 329 /* set the mask of a mark (might pin the object into memory */ 330 extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask); 331 /* attach the mark to both the group and the inode */ 332 extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group, 333 struct inode *inode, struct vfsmount *mnt, int allow_dups); 334 extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct fsnotify_group *group, 335 struct inode *inode, struct vfsmount *mnt, int allow_dups); 336 /* given a group and a mark, flag mark to be freed when all references are dropped */ 337 extern void fsnotify_destroy_mark(struct fsnotify_mark *mark, 338 struct fsnotify_group *group); 339 /* detach mark from inode / mount list, group list, drop inode reference */ 340 extern void fsnotify_detach_mark(struct fsnotify_mark *mark); 341 /* free mark */ 342 extern void fsnotify_free_mark(struct fsnotify_mark *mark); 343 /* run all the marks in a group, and clear all of the vfsmount marks */ 344 extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group); 345 /* run all the marks in a group, and clear all of the inode marks */ 346 extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group); 347 /* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/ 348 extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags); 349 extern void fsnotify_get_mark(struct fsnotify_mark *mark); 350 extern void fsnotify_put_mark(struct fsnotify_mark *mark); 351 extern void fsnotify_unmount_inodes(struct super_block *sb); 352 353 /* put here because inotify does some weird stuff when destroying watches */ 354 extern void fsnotify_init_event(struct fsnotify_event *event, 355 struct inode *to_tell, u32 mask); 356 357 #else 358 359 static inline int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is, 360 const unsigned char *name, u32 cookie) 361 { 362 return 0; 363 } 364 365 static inline int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask) 366 { 367 return 0; 368 } 369 370 static inline void __fsnotify_inode_delete(struct inode *inode) 371 {} 372 373 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt) 374 {} 375 376 static inline void fsnotify_update_flags(struct dentry *dentry) 377 {} 378 379 static inline u32 fsnotify_get_cookie(void) 380 { 381 return 0; 382 } 383 384 static inline void fsnotify_unmount_inodes(struct super_block *sb) 385 {} 386 387 #endif /* CONFIG_FSNOTIFY */ 388 389 #endif /* __KERNEL __ */ 390 391 #endif /* __LINUX_FSNOTIFY_BACKEND_H */ 392