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>
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>
12
13#include "fanotify.h"
14
15static bool should_merge(struct fsnotify_event *old_fsn,
16 struct fsnotify_event *new_fsn)
17{
18 struct fanotify_event_info *old, *new;
19
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);
23
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)
27 return true;
28 return false;
29}
30
31
32static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)
33{
34 struct fsnotify_event *test_event;
35
36 pr_debug("%s: list=%p event=%p\n", __func__, list, event);
37
38#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
39
40
41
42
43
44 if (event->mask & FAN_ALL_PERM_EVENTS)
45 return 0;
46#endif
47
48 list_for_each_entry_reverse(test_event, list, list) {
49 if (should_merge(test_event, event)) {
50 test_event->mask |= event->mask;
51 return 1;
52 }
53 }
54
55 return 0;
56}
57
58#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
59static int fanotify_get_response(struct fsnotify_group *group,
60 struct fanotify_perm_event_info *event,
61 struct fsnotify_iter_info *iter_info)
62{
63 int ret;
64
65 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
66
67
68
69
70
71 if (!fsnotify_prepare_user_wait(iter_info)) {
72 event->response = FAN_ALLOW;
73 goto out;
74 }
75
76 wait_event(group->fanotify_data.access_waitq, event->response);
77
78 fsnotify_finish_user_wait(iter_info);
79out:
80
81 switch (event->response) {
82 case FAN_ALLOW:
83 ret = 0;
84 break;
85 case FAN_DENY:
86 default:
87 ret = -EPERM;
88 }
89 event->response = 0;
90
91 pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
92 group, event, ret);
93
94 return ret;
95}
96#endif
97
98static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
99 struct fsnotify_mark *vfsmnt_mark,
100 u32 event_mask,
101 const void *data, int data_type)
102{
103 __u32 marks_mask, marks_ignored_mask;
104 const struct path *path = data;
105
106 pr_debug("%s: inode_mark=%p vfsmnt_mark=%p mask=%x data=%p"
107 " data_type=%d\n", __func__, inode_mark, vfsmnt_mark,
108 event_mask, data, data_type);
109
110
111 if (data_type != FSNOTIFY_EVENT_PATH)
112 return false;
113
114
115 if (!d_is_reg(path->dentry) &&
116 !d_can_lookup(path->dentry))
117 return false;
118
119 if (inode_mark && vfsmnt_mark) {
120 marks_mask = (vfsmnt_mark->mask | inode_mark->mask);
121 marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask);
122 } else if (inode_mark) {
123
124
125
126
127 if ((event_mask & FS_EVENT_ON_CHILD) &&
128 !(inode_mark->mask & FS_EVENT_ON_CHILD))
129 return false;
130 marks_mask = inode_mark->mask;
131 marks_ignored_mask = inode_mark->ignored_mask;
132 } else if (vfsmnt_mark) {
133 marks_mask = vfsmnt_mark->mask;
134 marks_ignored_mask = vfsmnt_mark->ignored_mask;
135 } else {
136 BUG();
137 }
138
139 if (d_is_dir(path->dentry) &&
140 !(marks_mask & FS_ISDIR & ~marks_ignored_mask))
141 return false;
142
143 if (event_mask & FAN_ALL_OUTGOING_EVENTS & marks_mask &
144 ~marks_ignored_mask)
145 return true;
146
147 return false;
148}
149
150struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask,
151 const struct path *path)
152{
153 struct fanotify_event_info *event;
154
155#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
156 if (mask & FAN_ALL_PERM_EVENTS) {
157 struct fanotify_perm_event_info *pevent;
158
159 pevent = kmem_cache_alloc(fanotify_perm_event_cachep,
160 GFP_KERNEL);
161 if (!pevent)
162 return NULL;
163 event = &pevent->fae;
164 pevent->response = 0;
165 goto init;
166 }
167#endif
168 event = kmem_cache_alloc(fanotify_event_cachep, GFP_KERNEL);
169 if (!event)
170 return NULL;
171init: __maybe_unused
172 fsnotify_init_event(&event->fse, inode, mask);
173 event->tgid = get_pid(task_tgid(current));
174 if (path) {
175 event->path = *path;
176 path_get(&event->path);
177 } else {
178 event->path.mnt = NULL;
179 event->path.dentry = NULL;
180 }
181 return event;
182}
183
184static int fanotify_handle_event(struct fsnotify_group *group,
185 struct inode *inode,
186 struct fsnotify_mark *inode_mark,
187 struct fsnotify_mark *fanotify_mark,
188 u32 mask, const void *data, int data_type,
189 const unsigned char *file_name, u32 cookie,
190 struct fsnotify_iter_info *iter_info)
191{
192 int ret = 0;
193 struct fanotify_event_info *event;
194 struct fsnotify_event *fsn_event;
195
196 BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
197 BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
198 BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
199 BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
200 BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
201 BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
202 BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
203 BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
204 BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
205 BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);
206
207 if (!fanotify_should_send_event(inode_mark, fanotify_mark, mask, data,
208 data_type))
209 return 0;
210
211 pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
212 mask);
213
214 event = fanotify_alloc_event(inode, mask, data);
215 if (unlikely(!event))
216 return -ENOMEM;
217
218 fsn_event = &event->fse;
219 ret = fsnotify_add_event(group, fsn_event, fanotify_merge);
220 if (ret) {
221
222 BUG_ON(ret == 1 && mask & FAN_ALL_PERM_EVENTS);
223
224 fsnotify_destroy_event(group, fsn_event);
225
226 return 0;
227 }
228
229#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
230 if (mask & FAN_ALL_PERM_EVENTS) {
231 ret = fanotify_get_response(group, FANOTIFY_PE(fsn_event),
232 iter_info);
233 fsnotify_destroy_event(group, fsn_event);
234 }
235#endif
236 return ret;
237}
238
239static void fanotify_free_group_priv(struct fsnotify_group *group)
240{
241 struct user_struct *user;
242
243 user = group->fanotify_data.user;
244 atomic_dec(&user->fanotify_listeners);
245 free_uid(user);
246}
247
248static void fanotify_free_event(struct fsnotify_event *fsn_event)
249{
250 struct fanotify_event_info *event;
251
252 event = FANOTIFY_E(fsn_event);
253 path_put(&event->path);
254 put_pid(event->tgid);
255#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
256 if (fsn_event->mask & FAN_ALL_PERM_EVENTS) {
257 kmem_cache_free(fanotify_perm_event_cachep,
258 FANOTIFY_PE(fsn_event));
259 return;
260 }
261#endif
262 kmem_cache_free(fanotify_event_cachep, event);
263}
264
265static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
266{
267 kmem_cache_free(fanotify_mark_cache, fsn_mark);
268}
269
270const struct fsnotify_ops fanotify_fsnotify_ops = {
271 .handle_event = fanotify_handle_event,
272 .free_group_priv = fanotify_free_group_priv,
273 .free_event = fanotify_free_event,
274 .free_mark = fanotify_free_mark,
275};
276
