1 #include <linux/fanotify.h>
2 #include <linux/fdtable.h>
3 #include <linux/fsnotify_backend.h>
4 #include <linux/init.h>
5 #include <linux/jiffies.h>
6 #include <linux/kernel.h> /* UINT_MAX */
7 #include <linux/mount.h>
8 #include <linux/sched.h>
9 #include <linux/types.h>
10 #include <linux/wait.h>
14 static bool should_merge(struct fsnotify_event *old_fsn,
15 struct fsnotify_event *new_fsn)
17 struct fanotify_event_info *old, *new;
19 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
20 /* dont merge two permission events */
21 if ((old_fsn->mask & FAN_ALL_PERM_EVENTS) &&
22 (new_fsn->mask & FAN_ALL_PERM_EVENTS))
25 pr_debug("%s: old=%p new=%p\n", __func__, old_fsn, new_fsn);
26 old = FANOTIFY_E(old_fsn);
27 new = FANOTIFY_E(new_fsn);
29 if (old_fsn->inode == new_fsn->inode && old->tgid == new->tgid &&
30 old->path.mnt == new->path.mnt &&
31 old->path.dentry == new->path.dentry)
36 /* and the list better be locked by something too! */
37 static struct fsnotify_event *fanotify_merge(struct list_head *list,
38 struct fsnotify_event *event)
40 struct fsnotify_event *test_event;
41 bool do_merge = false;
43 pr_debug("%s: list=%p event=%p\n", __func__, list, event);
45 list_for_each_entry_reverse(test_event, list, list) {
46 if (should_merge(test_event, event)) {
55 test_event->mask |= event->mask;
59 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
60 static int fanotify_get_response_from_access(struct fsnotify_group *group,
61 struct fanotify_event_info *event)
65 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
67 wait_event(group->fanotify_data.access_waitq, event->response ||
68 atomic_read(&group->fanotify_data.bypass_perm));
70 if (!event->response) /* bypass_perm set */
73 /* userspace responded, convert to something usable */
74 switch (event->response) {
84 pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
91 static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
92 struct fsnotify_mark *vfsmnt_mark,
94 void *data, int data_type)
96 __u32 marks_mask, marks_ignored_mask;
97 struct path *path = data;
99 pr_debug("%s: inode_mark=%p vfsmnt_mark=%p mask=%x data=%p"
100 " data_type=%d\n", __func__, inode_mark, vfsmnt_mark,
101 event_mask, data, data_type);
103 /* if we don't have enough info to send an event to userspace say no */
104 if (data_type != FSNOTIFY_EVENT_PATH)
107 /* sorry, fanotify only gives a damn about files and dirs */
108 if (!S_ISREG(path->dentry->d_inode->i_mode) &&
109 !S_ISDIR(path->dentry->d_inode->i_mode))
112 if (inode_mark && vfsmnt_mark) {
113 marks_mask = (vfsmnt_mark->mask | inode_mark->mask);
114 marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask);
115 } else if (inode_mark) {
117 * if the event is for a child and this inode doesn't care about
118 * events on the child, don't send it!
120 if ((event_mask & FS_EVENT_ON_CHILD) &&
121 !(inode_mark->mask & FS_EVENT_ON_CHILD))
123 marks_mask = inode_mark->mask;
124 marks_ignored_mask = inode_mark->ignored_mask;
125 } else if (vfsmnt_mark) {
126 marks_mask = vfsmnt_mark->mask;
127 marks_ignored_mask = vfsmnt_mark->ignored_mask;
132 if (S_ISDIR(path->dentry->d_inode->i_mode) &&
133 (marks_ignored_mask & FS_ISDIR))
136 if (event_mask & marks_mask & ~marks_ignored_mask)
142 static int fanotify_handle_event(struct fsnotify_group *group,
144 struct fsnotify_mark *inode_mark,
145 struct fsnotify_mark *fanotify_mark,
146 u32 mask, void *data, int data_type,
147 const unsigned char *file_name)
150 struct fanotify_event_info *event;
151 struct fsnotify_event *fsn_event;
152 struct fsnotify_event *notify_fsn_event;
154 BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
155 BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
156 BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
157 BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
158 BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
159 BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
160 BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
161 BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
162 BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
163 BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);
165 if (!fanotify_should_send_event(inode_mark, fanotify_mark, mask, data,
169 pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
172 event = kmem_cache_alloc(fanotify_event_cachep, GFP_KERNEL);
173 if (unlikely(!event))
176 fsn_event = &event->fse;
177 fsnotify_init_event(fsn_event, inode, mask);
178 event->tgid = get_pid(task_tgid(current));
179 if (data_type == FSNOTIFY_EVENT_PATH) {
180 struct path *path = data;
182 path_get(&event->path);
184 event->path.mnt = NULL;
185 event->path.dentry = NULL;
187 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
191 notify_fsn_event = fsnotify_add_notify_event(group, fsn_event,
193 if (notify_fsn_event) {
194 /* Our event wasn't used in the end. Free it. */
195 fsnotify_destroy_event(group, fsn_event);
196 if (IS_ERR(notify_fsn_event))
197 return PTR_ERR(notify_fsn_event);
198 /* We need to ask about a different events after a merge... */
199 event = FANOTIFY_E(notify_fsn_event);
200 fsn_event = notify_fsn_event;
203 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
204 if (fsn_event->mask & FAN_ALL_PERM_EVENTS)
205 ret = fanotify_get_response_from_access(group, event);
210 static void fanotify_free_group_priv(struct fsnotify_group *group)
212 struct user_struct *user;
214 user = group->fanotify_data.user;
215 atomic_dec(&user->fanotify_listeners);
219 static void fanotify_free_event(struct fsnotify_event *fsn_event)
221 struct fanotify_event_info *event;
223 event = FANOTIFY_E(fsn_event);
224 path_put(&event->path);
225 put_pid(event->tgid);
226 kmem_cache_free(fanotify_event_cachep, event);
229 const struct fsnotify_ops fanotify_fsnotify_ops = {
230 .handle_event = fanotify_handle_event,
231 .free_group_priv = fanotify_free_group_priv,
232 .free_event = fanotify_free_event,