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 19#include <asm/atomic.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_IN_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) 64 65#define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO) 66 67#define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \ 68 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \ 69 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \ 70 FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \ 71 FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \ 72 FS_OPEN_PERM | FS_ACCESS_PERM | FS_EXCL_UNLINK | \ 73 FS_IN_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \ 74 FS_DN_MULTISHOT | FS_EVENT_ON_CHILD) 75 76struct fsnotify_group; 77struct fsnotify_event; 78struct fsnotify_mark; 79struct fsnotify_event_private_data; 80 81/* 82 * Each group much define these ops. The fsnotify infrastructure will call 83 * these operations for each relevant group. 84 * 85 * should_send_event - given a group, inode, and mask this function determines 86 * if the group is interested in this event. 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 - this means that a mark has been flagged to die when everything 90 * finishes using it. The function is supplied with what must be a 91 * valid group and inode to use to clean up. 92 */ 93struct fsnotify_ops { 94 bool (*should_send_event)(struct fsnotify_group *group, struct inode *inode, 95 struct fsnotify_mark *inode_mark, 96 struct fsnotify_mark *vfsmount_mark, 97 __u32 mask, void *data, int data_type); 98 int (*handle_event)(struct fsnotify_group *group, 99 struct fsnotify_mark *inode_mark, 100 struct fsnotify_mark *vfsmount_mark, 101 struct fsnotify_event *event); 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_priv)(struct fsnotify_event_private_data *priv); 105}; 106 107/* 108 * A group is a "thing" that wants to receive notification about filesystem 109 * events. The mask holds the subset of event types this group cares about. 110 * refcnt on a group is up to the implementor and at any moment if it goes 0 111 * everything will be cleaned up. 112 */ 113struct fsnotify_group { 114 /* 115 * How the refcnt is used is up to each group. When the refcnt hits 0 116 * fsnotify will clean up all of the resources associated with this group. 117 * As an example, the dnotify group will always have a refcnt=1 and that 118 * will never change. Inotify, on the other hand, has a group per 119 * inotify_init() and the refcnt will hit 0 only when that fd has been 120 * closed. 121 */ 122 atomic_t refcnt; /* things with interest in this group */ 123 124 const struct fsnotify_ops *ops; /* how this group handles things */ 125 126 /* needed to send notification to userspace */ 127 struct mutex notification_mutex; /* protect the notification_list */ 128 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */ 129 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */ 130 unsigned int q_len; /* events on the queue */ 131 unsigned int max_events; /* maximum events allowed on the list */ 132 133 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */ 134 spinlock_t mark_lock; /* protect marks_list */ 135 atomic_t num_marks; /* 1 for each mark and 1 for not being 136 * past the point of no return when freeing 137 * a group */ 138 struct list_head marks_list; /* all inode marks for this group */ 139 140 /* groups can define private fields here or use the void *private */ 141 union { 142 void *private; 143#ifdef CONFIG_INOTIFY_USER 144 struct inotify_group_private_data { 145 spinlock_t idr_lock; 146 struct idr idr; 147 u32 last_wd; 148 struct fasync_struct *fa; /* async notification */ 149 struct user_struct *user; 150 } inotify_data; 151#endif 152#ifdef CONFIG_FANOTIFY 153 struct fanotify_group_private_data { 154#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 155 /* allows a group to block waiting for a userspace response */ 156 struct mutex access_mutex; 157 struct list_head access_list; 158 wait_queue_head_t access_waitq; 159 bool bypass_perm; /* protected by access_mutex */ 160#endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */ 161 int f_flags; 162 } fanotify_data; 163#endif /* CONFIG_FANOTIFY */ 164 }; 165}; 166 167/* 168 * A single event can be queued in multiple group->notification_lists. 169 * 170 * each group->notification_list will point to an event_holder which in turns points 171 * to the actual event that needs to be sent to userspace. 172 * 173 * Seemed cheaper to create a refcnt'd event and a small holder for every group 174 * than create a different event for every group 175 * 176 */ 177struct fsnotify_event_holder { 178 struct fsnotify_event *event; 179 struct list_head event_list; 180}; 181 182/* 183 * Inotify needs to tack data onto an event. This struct lets us later find the 184 * correct private data of the correct group. 185 */ 186struct fsnotify_event_private_data { 187 struct fsnotify_group *group; 188 struct list_head event_list; 189}; 190 191/* 192 * all of the information about the original object we want to now send to 193 * a group. If you want to carry more info from the accessing task to the 194 * listener this structure is where you need to be adding fields. 195 */ 196struct fsnotify_event { 197 /* 198 * If we create an event we are also likely going to need a holder 199 * to link to a group. So embed one holder in the event. Means only 200 * one allocation for the common case where we only have one group 201 */ 202 struct fsnotify_event_holder holder; 203 spinlock_t lock; /* protection for the associated event_holder and private_list */ 204 /* to_tell may ONLY be dereferenced during handle_event(). */ 205 struct inode *to_tell; /* either the inode the event happened to or its parent */ 206 /* 207 * depending on the event type we should have either a path or inode 208 * We hold a reference on path, but NOT on inode. Since we have the ref on 209 * the path, it may be dereferenced at any point during this object's 210 * lifetime. That reference is dropped when this object's refcnt hits 211 * 0. If this event contains an inode instead of a path, the inode may 212 * ONLY be used during handle_event(). 213 */ 214 union { 215 struct path path; 216 struct inode *inode; 217 }; 218/* when calling fsnotify tell it if the data is a path or inode */ 219#define FSNOTIFY_EVENT_NONE 0 220#define FSNOTIFY_EVENT_PATH 1 221#define FSNOTIFY_EVENT_INODE 2 222 int data_type; /* which of the above union we have */ 223 atomic_t refcnt; /* how many groups still are using/need to send this event */ 224 __u32 mask; /* the type of access, bitwise OR for FS_* event types */ 225 226 u32 sync_cookie; /* used to corrolate events, namely inotify mv events */ 227 const unsigned char *file_name; 228 size_t name_len; 229 struct pid *tgid; 230 231#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 232 __u32 response; /* userspace answer to question */ 233#endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */ 234 235 struct list_head private_data_list; /* groups can store private data here */ 236}; 237 238/* 239 * Inode specific fields in an fsnotify_mark 240 */ 241struct fsnotify_inode_mark { 242 struct inode *inode; /* inode this mark is associated with */ 243 struct hlist_node i_list; /* list of marks by inode->i_fsnotify_marks */ 244 struct list_head free_i_list; /* tmp list used when freeing this mark */ 245}; 246 247/* 248 * Mount point specific fields in an fsnotify_mark 249 */ 250struct fsnotify_vfsmount_mark { 251 struct vfsmount *mnt; /* vfsmount this mark is associated with */ 252 struct hlist_node m_list; /* list of marks by inode->i_fsnotify_marks */ 253 struct list_head free_m_list; /* tmp list used when freeing this mark */ 254}; 255 256/* 257 * a mark is simply an object attached to an in core inode which allows an 258 * fsnotify listener to indicate they are either no longer interested in events 259 * of a type matching mask or only interested in those events. 260 * 261 * these are flushed when an inode is evicted from core and may be flushed 262 * when the inode is modified (as seen by fsnotify_access). Some fsnotify users 263 * (such as dnotify) will flush these when the open fd is closed and not at 264 * inode eviction or modification. 265 */ 266struct fsnotify_mark { 267 __u32 mask; /* mask this mark is for */ 268 /* we hold ref for each i_list and g_list. also one ref for each 'thing' 269 * in kernel that found and may be using this mark. */ 270 atomic_t refcnt; /* active things looking at this mark */ 271 struct fsnotify_group *group; /* group this mark is for */ 272 struct list_head g_list; /* list of marks by group->i_fsnotify_marks */ 273 spinlock_t lock; /* protect group and inode */ 274 union { 275 struct fsnotify_inode_mark i; 276 struct fsnotify_vfsmount_mark m; 277 }; 278 __u32 ignored_mask; /* events types to ignore */ 279 struct list_head free_g_list; /* tmp list used when freeing this mark */ 280#define FSNOTIFY_MARK_FLAG_INODE 0x01 281#define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02 282#define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04 283#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08 284#define FSNOTIFY_MARK_FLAG_ALIVE 0x10 285 unsigned int flags; /* vfsmount or inode mark? */ 286 struct list_head destroy_list; 287 void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */ 288}; 289 290#ifdef CONFIG_FSNOTIFY 291 292/* called from the vfs helpers */ 293 294/* main fsnotify call to send events */ 295extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 296 const unsigned char *name, u32 cookie); 297extern void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask); 298extern void __fsnotify_inode_delete(struct inode *inode); 299extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt); 300extern u32 fsnotify_get_cookie(void); 301 302static inline int fsnotify_inode_watches_children(struct inode *inode) 303{ 304 /* FS_EVENT_ON_CHILD is set if the inode may care */ 305 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD)) 306 return 0; 307 /* this inode might care about child events, does it care about the 308 * specific set of events that can happen on a child? */ 309 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD; 310} 311 312/* 313 * Update the dentry with a flag indicating the interest of its parent to receive 314 * filesystem events when those events happens to this dentry->d_inode. 315 */ 316static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) 317{ 318 struct dentry *parent; 319 320 assert_spin_locked(&dcache_lock); 321 assert_spin_locked(&dentry->d_lock); 322 323 parent = dentry->d_parent; 324 if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode)) 325 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; 326 else 327 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; 328} 329 330/* 331 * fsnotify_d_instantiate - instantiate a dentry for inode 332 * Called with dcache_lock held. 333 */ 334static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) 335{ 336 if (!inode) 337 return; 338 339 assert_spin_locked(&dcache_lock); 340 341 spin_lock(&dentry->d_lock); 342 __fsnotify_update_dcache_flags(dentry); 343 spin_unlock(&dentry->d_lock); 344} 345 346/* called from fsnotify listeners, such as fanotify or dnotify */ 347 348/* get a reference to an existing or create a new group */ 349extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops); 350/* drop reference on a group from fsnotify_alloc_group */ 351extern void fsnotify_put_group(struct fsnotify_group *group); 352 353/* take a reference to an event */ 354extern void fsnotify_get_event(struct fsnotify_event *event); 355extern void fsnotify_put_event(struct fsnotify_event *event); 356/* find private data previously attached to an event and unlink it */ 357extern struct fsnotify_event_private_data *fsnotify_remove_priv_from_event(struct fsnotify_group *group, 358 struct fsnotify_event *event); 359 360/* attach the event to the group notification queue */ 361extern struct fsnotify_event *fsnotify_add_notify_event(struct fsnotify_group *group, 362 struct fsnotify_event *event, 363 struct fsnotify_event_private_data *priv, 364 struct fsnotify_event *(*merge)(struct list_head *, 365 struct fsnotify_event *)); 366/* true if the group notification queue is empty */ 367extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group); 368/* return, but do not dequeue the first event on the notification queue */ 369extern struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group); 370/* return AND dequeue the first event on the notification queue */ 371extern struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group); 372 373/* functions used to manipulate the marks attached to inodes */ 374 375/* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */ 376extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt); 377/* run all marks associated with an inode and update inode->i_fsnotify_mask */ 378extern void fsnotify_recalc_inode_mask(struct inode *inode); 379extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark)); 380/* find (and take a reference) to a mark associated with group and inode */ 381extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode); 382/* find (and take a reference) to a mark associated with group and vfsmount */ 383extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt); 384/* copy the values from old into new */ 385extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old); 386/* set the ignored_mask of a mark */ 387extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask); 388/* set the mask of a mark (might pin the object into memory */ 389extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask); 390/* attach the mark to both the group and the inode */ 391extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group, 392 struct inode *inode, struct vfsmount *mnt, int allow_dups); 393/* given a mark, flag it to be freed when all references are dropped */ 394extern void fsnotify_destroy_mark(struct fsnotify_mark *mark); 395/* run all the marks in a group, and clear all of the vfsmount marks */ 396extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group); 397/* run all the marks in a group, and clear all of the inode marks */ 398extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group); 399/* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/ 400extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags); 401/* run all the marks in a group, and flag them to be freed */ 402extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group); 403extern void fsnotify_get_mark(struct fsnotify_mark *mark); 404extern void fsnotify_put_mark(struct fsnotify_mark *mark); 405extern void fsnotify_unmount_inodes(struct list_head *list); 406 407/* put here because inotify does some weird stuff when destroying watches */ 408extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask, 409 void *data, int data_is, 410 const unsigned char *name, 411 u32 cookie, gfp_t gfp); 412 413/* fanotify likes to change events after they are on lists... */ 414extern struct fsnotify_event *fsnotify_clone_event(struct fsnotify_event *old_event); 415extern int fsnotify_replace_event(struct fsnotify_event_holder *old_holder, 416 struct fsnotify_event *new_event); 417 418#else 419 420static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 421 const unsigned char *name, u32 cookie) 422{ 423 return 0; 424} 425 426static inline void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) 427{} 428 429static inline void __fsnotify_inode_delete(struct inode *inode) 430{} 431 432static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt) 433{} 434 435static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) 436{} 437 438static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) 439{} 440 441static inline u32 fsnotify_get_cookie(void) 442{ 443 return 0; 444} 445 446static inline void fsnotify_unmount_inodes(struct list_head *list) 447{} 448 449#endif /* CONFIG_FSNOTIFY */ 450 451#endif /* __KERNEL __ */ 452 453#endif /* __LINUX_FSNOTIFY_BACKEND_H */ 454