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 pr_debug("%s: old=%p new=%p\n", __func__, old_fsn, new_fsn);
20 old = FANOTIFY_E(old_fsn);
21 new = FANOTIFY_E(new_fsn);
23 if (old_fsn->inode == new_fsn->inode && old->tgid == new->tgid &&
24 old->path.mnt == new->path.mnt &&
25 old->path.dentry == new->path.dentry)
30 /* and the list better be locked by something too! */
31 static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)
33 struct fsnotify_event *test_event;
34 bool do_merge = false;
36 pr_debug("%s: list=%p event=%p\n", __func__, list, event);
38 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
40 * Don't merge a permission event with any other event so that we know
41 * the event structure we have created in fanotify_handle_event() is the
42 * one we should check for permission response.
44 if (event->mask & FAN_ALL_PERM_EVENTS)
48 list_for_each_entry_reverse(test_event, list, list) {
49 if (should_merge(test_event, event)) {
58 test_event->mask |= event->mask;
62 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
63 static int fanotify_get_response_from_access(struct fsnotify_group *group,
64 struct fanotify_event_info *event)
68 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
70 wait_event(group->fanotify_data.access_waitq, event->response ||
71 atomic_read(&group->fanotify_data.bypass_perm));
73 if (!event->response) /* bypass_perm set */
76 /* userspace responded, convert to something usable */
77 switch (event->response) {
87 pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
94 static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
95 struct fsnotify_mark *vfsmnt_mark,
97 void *data, int data_type)
99 __u32 marks_mask, marks_ignored_mask;
100 struct path *path = data;
102 pr_debug("%s: inode_mark=%p vfsmnt_mark=%p mask=%x data=%p"
103 " data_type=%d\n", __func__, inode_mark, vfsmnt_mark,
104 event_mask, data, data_type);
106 /* if we don't have enough info to send an event to userspace say no */
107 if (data_type != FSNOTIFY_EVENT_PATH)
110 /* sorry, fanotify only gives a damn about files and dirs */
111 if (!S_ISREG(path->dentry->d_inode->i_mode) &&
112 !S_ISDIR(path->dentry->d_inode->i_mode))
115 if (inode_mark && vfsmnt_mark) {
116 marks_mask = (vfsmnt_mark->mask | inode_mark->mask);
117 marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask);
118 } else if (inode_mark) {
120 * if the event is for a child and this inode doesn't care about
121 * events on the child, don't send it!
123 if ((event_mask & FS_EVENT_ON_CHILD) &&
124 !(inode_mark->mask & FS_EVENT_ON_CHILD))
126 marks_mask = inode_mark->mask;
127 marks_ignored_mask = inode_mark->ignored_mask;
128 } else if (vfsmnt_mark) {
129 marks_mask = vfsmnt_mark->mask;
130 marks_ignored_mask = vfsmnt_mark->ignored_mask;
135 if (S_ISDIR(path->dentry->d_inode->i_mode) &&
136 (marks_ignored_mask & FS_ISDIR))
139 if (event_mask & marks_mask & ~marks_ignored_mask)
145 static int fanotify_handle_event(struct fsnotify_group *group,
147 struct fsnotify_mark *inode_mark,
148 struct fsnotify_mark *fanotify_mark,
149 u32 mask, void *data, int data_type,
150 const unsigned char *file_name)
153 struct fanotify_event_info *event;
154 struct fsnotify_event *fsn_event;
156 BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
157 BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
158 BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
159 BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
160 BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
161 BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
162 BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
163 BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
164 BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
165 BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);
167 if (!fanotify_should_send_event(inode_mark, fanotify_mark, mask, data,
171 pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
174 event = kmem_cache_alloc(fanotify_event_cachep, GFP_KERNEL);
175 if (unlikely(!event))
178 fsn_event = &event->fse;
179 fsnotify_init_event(fsn_event, inode, mask);
180 event->tgid = get_pid(task_tgid(current));
181 if (data_type == FSNOTIFY_EVENT_PATH) {
182 struct path *path = data;
184 path_get(&event->path);
186 event->path.mnt = NULL;
187 event->path.dentry = NULL;
189 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
193 ret = fsnotify_add_notify_event(group, fsn_event, fanotify_merge);
195 BUG_ON(mask & FAN_ALL_PERM_EVENTS);
196 /* Our event wasn't used in the end. Free it. */
197 fsnotify_destroy_event(group, fsn_event);
201 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
202 if (mask & FAN_ALL_PERM_EVENTS) {
203 ret = fanotify_get_response_from_access(group, event);
204 fsnotify_destroy_event(group, fsn_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,