1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/fanotify.h>
3 #include <linux/fdtable.h>
4 #include <linux/fsnotify_backend.h>
5 #include <linux/init.h>
6 #include <linux/jiffies.h>
7 #include <linux/kernel.h> /* UINT_MAX */
8 #include <linux/mount.h>
9 #include <linux/sched.h>
10 #include <linux/sched/user.h>
11 #include <linux/types.h>
12 #include <linux/wait.h>
13 #include <linux/audit.h>
17 static bool should_merge(struct fsnotify_event *old_fsn,
18 struct fsnotify_event *new_fsn)
20 struct fanotify_event_info *old, *new;
22 pr_debug("%s: old=%p new=%p\n", __func__, old_fsn, new_fsn);
23 old = FANOTIFY_E(old_fsn);
24 new = FANOTIFY_E(new_fsn);
26 if (old_fsn->inode == new_fsn->inode && old->tgid == new->tgid &&
27 old->path.mnt == new->path.mnt &&
28 old->path.dentry == new->path.dentry)
33 /* and the list better be locked by something too! */
34 static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)
36 struct fsnotify_event *test_event;
38 pr_debug("%s: list=%p event=%p\n", __func__, list, event);
41 * Don't merge a permission event with any other event so that we know
42 * the event structure we have created in fanotify_handle_event() is the
43 * one we should check for permission response.
45 if (fanotify_is_perm_event(event->mask))
48 list_for_each_entry_reverse(test_event, list, list) {
49 if (should_merge(test_event, event)) {
50 test_event->mask |= event->mask;
58 static int fanotify_get_response(struct fsnotify_group *group,
59 struct fanotify_perm_event_info *event,
60 struct fsnotify_iter_info *iter_info)
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 & ~FAN_AUDIT) {
78 /* Check if the response should be audited */
79 if (event->response & FAN_AUDIT)
80 audit_fanotify(event->response & ~FAN_AUDIT);
84 pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
90 static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
91 struct fsnotify_mark *vfsmnt_mark,
93 const void *data, int data_type)
95 __u32 marks_mask, marks_ignored_mask;
96 const struct path *path = data;
98 pr_debug("%s: inode_mark=%p vfsmnt_mark=%p mask=%x data=%p"
99 " data_type=%d\n", __func__, inode_mark, vfsmnt_mark,
100 event_mask, data, data_type);
102 /* if we don't have enough info to send an event to userspace say no */
103 if (data_type != FSNOTIFY_EVENT_PATH)
106 /* sorry, fanotify only gives a damn about files and dirs */
107 if (!d_is_reg(path->dentry) &&
108 !d_can_lookup(path->dentry))
111 if (inode_mark && vfsmnt_mark) {
112 marks_mask = (vfsmnt_mark->mask | inode_mark->mask);
113 marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask);
114 } else if (inode_mark) {
116 * if the event is for a child and this inode doesn't care about
117 * events on the child, don't send it!
119 if ((event_mask & FS_EVENT_ON_CHILD) &&
120 !(inode_mark->mask & FS_EVENT_ON_CHILD))
122 marks_mask = inode_mark->mask;
123 marks_ignored_mask = inode_mark->ignored_mask;
124 } else if (vfsmnt_mark) {
125 marks_mask = vfsmnt_mark->mask;
126 marks_ignored_mask = vfsmnt_mark->ignored_mask;
131 if (d_is_dir(path->dentry) &&
132 !(marks_mask & FS_ISDIR & ~marks_ignored_mask))
135 if (event_mask & FAN_ALL_OUTGOING_EVENTS & marks_mask &
142 struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask,
143 const struct path *path)
145 struct fanotify_event_info *event;
147 if (fanotify_is_perm_event(mask)) {
148 struct fanotify_perm_event_info *pevent;
150 pevent = kmem_cache_alloc(fanotify_perm_event_cachep,
154 event = &pevent->fae;
155 pevent->response = 0;
158 event = kmem_cache_alloc(fanotify_event_cachep, GFP_KERNEL);
162 fsnotify_init_event(&event->fse, inode, mask);
163 event->tgid = get_pid(task_tgid(current));
166 path_get(&event->path);
168 event->path.mnt = NULL;
169 event->path.dentry = NULL;
174 static int fanotify_handle_event(struct fsnotify_group *group,
176 struct fsnotify_mark *inode_mark,
177 struct fsnotify_mark *fanotify_mark,
178 u32 mask, const void *data, int data_type,
179 const unsigned char *file_name, u32 cookie,
180 struct fsnotify_iter_info *iter_info)
183 struct fanotify_event_info *event;
184 struct fsnotify_event *fsn_event;
186 BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
187 BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
188 BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
189 BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
190 BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
191 BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
192 BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
193 BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
194 BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
195 BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);
197 if (!fanotify_should_send_event(inode_mark, fanotify_mark, mask, data,
201 pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
204 if (fanotify_is_perm_event(mask)) {
206 * fsnotify_prepare_user_wait() fails if we race with mark
207 * deletion. Just let the operation pass in that case.
209 if (!fsnotify_prepare_user_wait(iter_info))
213 event = fanotify_alloc_event(inode, mask, data);
215 if (unlikely(!event))
218 fsn_event = &event->fse;
219 ret = fsnotify_add_event(group, fsn_event, fanotify_merge);
221 /* Permission events shouldn't be merged */
222 BUG_ON(ret == 1 && mask & FAN_ALL_PERM_EVENTS);
223 /* Our event wasn't used in the end. Free it. */
224 fsnotify_destroy_event(group, fsn_event);
227 } else if (fanotify_is_perm_event(mask)) {
228 ret = fanotify_get_response(group, FANOTIFY_PE(fsn_event),
230 fsnotify_destroy_event(group, fsn_event);
233 if (fanotify_is_perm_event(mask))
234 fsnotify_finish_user_wait(iter_info);
239 static void fanotify_free_group_priv(struct fsnotify_group *group)
241 struct user_struct *user;
243 user = group->fanotify_data.user;
244 atomic_dec(&user->fanotify_listeners);
248 static void fanotify_free_event(struct fsnotify_event *fsn_event)
250 struct fanotify_event_info *event;
252 event = FANOTIFY_E(fsn_event);
253 path_put(&event->path);
254 put_pid(event->tgid);
255 if (fanotify_is_perm_event(fsn_event->mask)) {
256 kmem_cache_free(fanotify_perm_event_cachep,
257 FANOTIFY_PE(fsn_event));
260 kmem_cache_free(fanotify_event_cachep, event);
263 static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
265 kmem_cache_free(fanotify_mark_cache, fsn_mark);
268 const struct fsnotify_ops fanotify_fsnotify_ops = {
269 .handle_event = fanotify_handle_event,
270 .free_group_priv = fanotify_free_group_priv,
271 .free_event = fanotify_free_event,
272 .free_mark = fanotify_free_mark,