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/sched/user.h>
10 #include <linux/types.h>
11 #include <linux/wait.h>
15 static bool should_merge(struct fsnotify_event *old_fsn,
16 struct fsnotify_event *new_fsn)
18 struct fanotify_event_info *old, *new;
20 pr_debug("%s: old=%p new=%p\n", __func__, old_fsn, new_fsn);
21 old = FANOTIFY_E(old_fsn);
22 new = FANOTIFY_E(new_fsn);
24 if (old_fsn->inode == new_fsn->inode && old->tgid == new->tgid &&
25 old->path.mnt == new->path.mnt &&
26 old->path.dentry == new->path.dentry)
31 /* and the list better be locked by something too! */
32 static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)
34 struct fsnotify_event *test_event;
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)) {
50 test_event->mask |= event->mask;
58 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
59 static int fanotify_get_response(struct fsnotify_group *group,
60 struct fanotify_perm_event_info *event)
64 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
66 wait_event(group->fanotify_data.access_waitq, event->response);
68 /* userspace responded, convert to something usable */
69 switch (event->response) {
79 pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
86 static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
87 struct fsnotify_mark *vfsmnt_mark,
89 const void *data, int data_type)
91 __u32 marks_mask, marks_ignored_mask;
92 const struct path *path = data;
94 pr_debug("%s: inode_mark=%p vfsmnt_mark=%p mask=%x data=%p"
95 " data_type=%d\n", __func__, inode_mark, vfsmnt_mark,
96 event_mask, data, data_type);
98 /* if we don't have enough info to send an event to userspace say no */
99 if (data_type != FSNOTIFY_EVENT_PATH)
102 /* sorry, fanotify only gives a damn about files and dirs */
103 if (!d_is_reg(path->dentry) &&
104 !d_can_lookup(path->dentry))
107 if (inode_mark && vfsmnt_mark) {
108 marks_mask = (vfsmnt_mark->mask | inode_mark->mask);
109 marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask);
110 } else if (inode_mark) {
112 * if the event is for a child and this inode doesn't care about
113 * events on the child, don't send it!
115 if ((event_mask & FS_EVENT_ON_CHILD) &&
116 !(inode_mark->mask & FS_EVENT_ON_CHILD))
118 marks_mask = inode_mark->mask;
119 marks_ignored_mask = inode_mark->ignored_mask;
120 } else if (vfsmnt_mark) {
121 marks_mask = vfsmnt_mark->mask;
122 marks_ignored_mask = vfsmnt_mark->ignored_mask;
127 if (d_is_dir(path->dentry) &&
128 !(marks_mask & FS_ISDIR & ~marks_ignored_mask))
131 if (event_mask & FAN_ALL_OUTGOING_EVENTS & marks_mask &
138 struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask,
139 const struct path *path)
141 struct fanotify_event_info *event;
143 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
144 if (mask & FAN_ALL_PERM_EVENTS) {
145 struct fanotify_perm_event_info *pevent;
147 pevent = kmem_cache_alloc(fanotify_perm_event_cachep,
151 event = &pevent->fae;
152 pevent->response = 0;
156 event = kmem_cache_alloc(fanotify_event_cachep, GFP_KERNEL);
160 fsnotify_init_event(&event->fse, inode, mask);
161 event->tgid = get_pid(task_tgid(current));
164 path_get(&event->path);
166 event->path.mnt = NULL;
167 event->path.dentry = NULL;
172 static int fanotify_handle_event(struct fsnotify_group *group,
174 struct fsnotify_mark *inode_mark,
175 struct fsnotify_mark *fanotify_mark,
176 u32 mask, const void *data, int data_type,
177 const unsigned char *file_name, u32 cookie)
180 struct fanotify_event_info *event;
181 struct fsnotify_event *fsn_event;
183 BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
184 BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
185 BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
186 BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
187 BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
188 BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
189 BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
190 BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
191 BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
192 BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);
194 if (!fanotify_should_send_event(inode_mark, fanotify_mark, mask, data,
198 pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
201 event = fanotify_alloc_event(inode, mask, data);
202 if (unlikely(!event))
205 fsn_event = &event->fse;
206 ret = fsnotify_add_event(group, fsn_event, fanotify_merge);
208 /* Permission events shouldn't be merged */
209 BUG_ON(ret == 1 && mask & FAN_ALL_PERM_EVENTS);
210 /* Our event wasn't used in the end. Free it. */
211 fsnotify_destroy_event(group, fsn_event);
216 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
217 if (mask & FAN_ALL_PERM_EVENTS) {
218 ret = fanotify_get_response(group, FANOTIFY_PE(fsn_event));
219 fsnotify_destroy_event(group, fsn_event);
225 static void fanotify_free_group_priv(struct fsnotify_group *group)
227 struct user_struct *user;
229 user = group->fanotify_data.user;
230 atomic_dec(&user->fanotify_listeners);
234 static void fanotify_free_event(struct fsnotify_event *fsn_event)
236 struct fanotify_event_info *event;
238 event = FANOTIFY_E(fsn_event);
239 path_put(&event->path);
240 put_pid(event->tgid);
241 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
242 if (fsn_event->mask & FAN_ALL_PERM_EVENTS) {
243 kmem_cache_free(fanotify_perm_event_cachep,
244 FANOTIFY_PE(fsn_event));
248 kmem_cache_free(fanotify_event_cachep, event);
251 const struct fsnotify_ops fanotify_fsnotify_ops = {
252 .handle_event = fanotify_handle_event,
253 .free_group_priv = fanotify_free_group_priv,
254 .free_event = fanotify_free_event,