1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
|
#include <linux/fanotify.h>
#include <linux/fdtable.h>
#include <linux/fsnotify_backend.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/kernel.h> /* UINT_MAX */
#include <linux/mount.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/wait.h>
static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new)
{
pr_debug("%s: old=%p new=%p\n", __func__, old, new);
if (old->to_tell == new->to_tell &&
old->data_type == new->data_type &&
old->tgid == new->tgid) {
switch (old->data_type) {
case (FSNOTIFY_EVENT_PATH):
#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
/* dont merge two permission events */
if ((old->mask & FAN_ALL_PERM_EVENTS) &&
(new->mask & FAN_ALL_PERM_EVENTS))
return false;
#endif
if ((old->path.mnt == new->path.mnt) &&
(old->path.dentry == new->path.dentry))
return true;
break;
case (FSNOTIFY_EVENT_NONE):
return true;
default:
BUG();
};
}
return false;
}
/* and the list better be locked by something too! */
static struct fsnotify_event *fanotify_merge(struct list_head *list,
struct fsnotify_event *event)
{
struct fsnotify_event_holder *test_holder;
struct fsnotify_event *test_event = NULL;
struct fsnotify_event *new_event;
pr_debug("%s: list=%p event=%p\n", __func__, list, event);
list_for_each_entry_reverse(test_holder, list, event_list) {
if (should_merge(test_holder->event, event)) {
test_event = test_holder->event;
break;
}
}
if (!test_event)
return NULL;
fsnotify_get_event(test_event);
/* if they are exactly the same we are done */
if (test_event->mask == event->mask)
return test_event;
/*
* if the refcnt == 2 this is the only queue
* for this event and so we can update the mask
* in place.
*/
if (atomic_read(&test_event->refcnt) == 2) {
test_event->mask |= event->mask;
return test_event;
}
new_event = fsnotify_clone_event(test_event);
/* done with test_event */
fsnotify_put_event(test_event);
/* couldn't allocate memory, merge was not possible */
if (unlikely(!new_event))
return ERR_PTR(-ENOMEM);
/* build new event and replace it on the list */
new_event->mask = (test_event->mask | event->mask);
fsnotify_replace_event(test_holder, new_event);
/* we hold a reference on new_event from clone_event */
return new_event;
}
#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
static int fanotify_get_response_from_access(struct fsnotify_group *group,
struct fsnotify_event *event)
{
int ret;
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
wait_event(group->fanotify_data.access_waitq, event->response ||
atomic_read(&group->fanotify_data.bypass_perm));
if (!event->response) /* bypass_perm set */
return 0;
/* userspace responded, convert to something usable */
spin_lock(&event->lock);
switch (event->response) {
case FAN_ALLOW:
ret = 0;
break;
case FAN_DENY:
default:
ret = -EPERM;
}
event->response = 0;
spin_unlock(&event->lock);
pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
group, event, ret);
return ret;
}
#endif
static int fanotify_handle_event(struct fsnotify_group *group,
struct fsnotify_mark *inode_mark,
struct fsnotify_mark *fanotify_mark,
struct fsnotify_event *event)
{
int ret = 0;
struct fsnotify_event *notify_event = NULL;
BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
notify_event = fsnotify_add_notify_event(group, event, NULL, fanotify_merge);
if (IS_ERR(notify_event))
return PTR_ERR(notify_event);
#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
if (event->mask & FAN_ALL_PERM_EVENTS) {
/* if we merged we need to wait on the new event */
if (notify_event)
event = notify_event;
ret = fanotify_get_response_from_access(group, event);
}
#endif
if (notify_event)
fsnotify_put_event(notify_event);
return ret;
}
static bool fanotify_should_send_event(struct fsnotify_group *group,
struct inode *to_tell,
struct fsnotify_mark *inode_mark,
struct fsnotify_mark *vfsmnt_mark,
__u32 event_mask, void *data, int data_type)
{
__u32 marks_mask, marks_ignored_mask;
struct path *path = data;
pr_debug("%s: group=%p to_tell=%p inode_mark=%p vfsmnt_mark=%p "
"mask=%x data=%p data_type=%d\n", __func__, group, to_tell,
inode_mark, vfsmnt_mark, event_mask, data, data_type);
/* if we don't have enough info to send an event to userspace say no */
if (data_type != FSNOTIFY_EVENT_PATH)
return false;
/* sorry, fanotify only gives a damn about files and dirs */
if (!S_ISREG(path->dentry->d_inode->i_mode) &&
!S_ISDIR(path->dentry->d_inode->i_mode))
return false;
if (inode_mark && vfsmnt_mark) {
marks_mask = (vfsmnt_mark->mask | inode_mark->mask);
marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask);
} else if (inode_mark) {
/*
* if the event is for a child and this inode doesn't care about
* events on the child, don't send it!
*/
if ((event_mask & FS_EVENT_ON_CHILD) &&
!(inode_mark->mask & FS_EVENT_ON_CHILD))
return false;
marks_mask = inode_mark->mask;
marks_ignored_mask = inode_mark->ignored_mask;
} else if (vfsmnt_mark) {
marks_mask = vfsmnt_mark->mask;
marks_ignored_mask = vfsmnt_mark->ignored_mask;
} else {
BUG();
}
if (S_ISDIR(path->dentry->d_inode->i_mode) &&
(marks_ignored_mask & FS_ISDIR))
return false;
if (event_mask & marks_mask & ~marks_ignored_mask)
return true;
return false;
}
static void fanotify_free_group_priv(struct fsnotify_group *group)
{
struct user_struct *user;
user = group->fanotify_data.user;
atomic_dec(&user->fanotify_listeners);
free_uid(user);
}
const struct fsnotify_ops fanotify_fsnotify_ops = {
.handle_event = fanotify_handle_event,
.should_send_event = fanotify_should_send_event,
.free_group_priv = fanotify_free_group_priv,
.free_event_priv = NULL,
.freeing_mark = NULL,
};
|
