1 #include <linux/fanotify.h>
2 #include <linux/fdtable.h>
3 #include <linux/fsnotify_backend.h>
4 #include <linux/init.h>
5 #include <linux/kernel.h> /* UINT_MAX */
6 #include <linux/mount.h>
7 #include <linux/types.h>
9 static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new)
11 pr_debug("%s: old=%p new=%p\n", __func__, old, new);
13 if (old->to_tell == new->to_tell &&
14 old->data_type == new->data_type &&
15 old->tgid == new->tgid) {
16 switch (old->data_type) {
17 case (FSNOTIFY_EVENT_PATH):
18 if ((old->path.mnt == new->path.mnt) &&
19 (old->path.dentry == new->path.dentry))
21 case (FSNOTIFY_EVENT_NONE):
30 static int fanotify_merge(struct list_head *list,
31 struct fsnotify_event *event,
34 struct fsnotify_event_holder *test_holder;
35 struct fsnotify_event *test_event;
36 struct fsnotify_event *new_event;
39 pr_debug("%s: list=%p event=%p\n", __func__, list, event);
41 /* and the list better be locked by something too! */
43 list_for_each_entry_reverse(test_holder, list, event_list) {
44 test_event = test_holder->event;
45 if (should_merge(test_event, event)) {
48 /* if they are exactly the same we are done */
49 if (test_event->mask == event->mask)
53 * if the refcnt == 1 this is the only queue
54 * for this event and so we can update the mask
57 if (atomic_read(&test_event->refcnt) == 1) {
58 test_event->mask |= event->mask;
62 /* can't allocate memory, merge was no possible */
63 new_event = fsnotify_clone_event(test_event);
64 if (unlikely(!new_event)) {
69 /* build new event and replace it on the list */
70 new_event->mask = (test_event->mask | event->mask);
71 fsnotify_replace_event(test_holder, new_event);
72 /* match ref from fsnotify_clone_event() */
73 fsnotify_put_event(new_event);
82 static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)
87 BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
88 BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
89 BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
90 BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
91 BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
92 BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
93 BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
95 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
97 ret = fsnotify_add_notify_event(group, event, NULL, fanotify_merge, NULL);
98 /* -EEXIST means this event was merged with another, not that it was an error */
104 static bool should_send_vfsmount_event(struct fsnotify_group *group, struct vfsmount *mnt,
105 struct inode *inode, __u32 mask)
107 struct fsnotify_mark *mnt_mark;
108 struct fsnotify_mark *inode_mark;
110 pr_debug("%s: group=%p vfsmount=%p mask=%x\n",
111 __func__, group, mnt, mask);
113 mnt_mark = fsnotify_find_vfsmount_mark(group, mnt);
117 mask &= mnt_mark->mask;
118 mask &= ~mnt_mark->ignored_mask;
121 inode_mark = fsnotify_find_inode_mark(group, inode);
123 mask &= ~inode_mark->ignored_mask;
124 fsnotify_put_mark(inode_mark);
128 /* find took a reference */
129 fsnotify_put_mark(mnt_mark);
134 static bool should_send_inode_event(struct fsnotify_group *group, struct inode *inode,
137 struct fsnotify_mark *fsn_mark;
139 pr_debug("%s: group=%p inode=%p mask=%x\n",
140 __func__, group, inode, mask);
142 fsn_mark = fsnotify_find_inode_mark(group, inode);
146 /* if the event is for a child and this inode doesn't care about
147 * events on the child, don't send it! */
148 if ((mask & FS_EVENT_ON_CHILD) &&
149 !(fsn_mark->mask & FS_EVENT_ON_CHILD)) {
153 * We care about children, but do we care about this particular
156 mask &= ~FS_EVENT_ON_CHILD;
157 mask &= fsn_mark->mask;
158 mask &= ~fsn_mark->ignored_mask;
161 /* find took a reference */
162 fsnotify_put_mark(fsn_mark);
167 static bool fanotify_should_send_event(struct fsnotify_group *group, struct inode *to_tell,
168 struct vfsmount *mnt, __u32 mask, void *data,
171 pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x data=%p data_type=%d\n",
172 __func__, group, to_tell, mnt, mask, data, data_type);
174 /* sorry, fanotify only gives a damn about files and dirs */
175 if (!S_ISREG(to_tell->i_mode) &&
176 !S_ISDIR(to_tell->i_mode))
179 /* if we don't have enough info to send an event to userspace say no */
180 if (data_type != FSNOTIFY_EVENT_PATH)
184 return should_send_vfsmount_event(group, mnt, to_tell, mask);
186 return should_send_inode_event(group, to_tell, mask);
189 const struct fsnotify_ops fanotify_fsnotify_ops = {
190 .handle_event = fanotify_handle_event,
191 .should_send_event = fanotify_should_send_event,
192 .free_group_priv = NULL,
193 .free_event_priv = NULL,
194 .freeing_mark = NULL,