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
|
#include <linux/fdtable.h>
#include <linux/fsnotify_backend.h>
#include <linux/init.h>
#include <linux/kernel.h> /* UINT_MAX */
#include <linux/types.h>
#include "fanotify.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)) {
switch (old->data_type) {
case (FSNOTIFY_EVENT_PATH):
if ((old->path.mnt == new->path.mnt) &&
(old->path.dentry == new->path.dentry))
return true;
case (FSNOTIFY_EVENT_NONE):
return true;
default:
BUG();
};
}
return false;
}
static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)
{
struct fsnotify_event_holder *test_holder;
struct fsnotify_event *test_event;
struct fsnotify_event *new_event;
int ret = 0;
pr_debug("%s: list=%p event=%p\n", __func__, list, event);
/* and the list better be locked by something too! */
list_for_each_entry_reverse(test_holder, list, event_list) {
test_event = test_holder->event;
if (should_merge(test_event, event)) {
ret = -EEXIST;
/* if they are exactly the same we are done */
if (test_event->mask == event->mask)
goto out;
/* can't allocate memory, merge was no possible */
new_event = fsnotify_clone_event(test_event);
if (unlikely(!new_event)) {
ret = 0;
goto out;
}
/* build new event and replace it on the list */
new_event->mask = (test_event->mask | event->mask);
fsnotify_replace_event(test_holder, new_event);
/* match ref from fsnotify_clone_event() */
fsnotify_put_event(new_event);
break;
}
}
out:
return ret;
}
static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)
{
int ret;
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);
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
ret = fsnotify_add_notify_event(group, event, NULL, fanotify_merge);
/* -EEXIST means this event was merged with another, not that it was an error */
if (ret == -EEXIST)
ret = 0;
return ret;
}
static bool fanotify_should_send_event(struct fsnotify_group *group, struct inode *inode,
struct vfsmount *mnt, __u32 mask, void *data,
int data_type)
{
struct fsnotify_mark *fsn_mark;
bool send;
pr_debug("%s: group=%p inode=%p mask=%x data=%p data_type=%d\n",
__func__, group, inode, mask, data, data_type);
/* sorry, fanotify only gives a damn about files and dirs */
if (!S_ISREG(inode->i_mode) &&
!S_ISDIR(inode->i_mode))
return false;
/* if we don't have enough info to send an event to userspace say no */
if (data_type != FSNOTIFY_EVENT_PATH)
return false;
fsn_mark = fsnotify_find_mark(group, inode);
if (!fsn_mark)
return false;
/* if the event is for a child and this inode doesn't care about
* events on the child, don't send it! */
if ((mask & FS_EVENT_ON_CHILD) &&
!(fsn_mark->mask & FS_EVENT_ON_CHILD)) {
send = false;
} else {
/*
* We care about children, but do we care about this particular
* type of event?
*/
mask = (mask & ~FS_EVENT_ON_CHILD);
send = (fsn_mark->mask & mask);
}
/* find took a reference */
fsnotify_put_mark(fsn_mark);
return send;
}
const struct fsnotify_ops fanotify_fsnotify_ops = {
.handle_event = fanotify_handle_event,
.should_send_event = fanotify_should_send_event,
.free_group_priv = NULL,
.free_event_priv = NULL,
.freeing_mark = NULL,
};
|
