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Commit | Line | Data |
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ff0b16a9 EP |
1 | #include <linux/fdtable.h> |
2 | #include <linux/fsnotify_backend.h> | |
3 | #include <linux/init.h> | |
4 | #include <linux/kernel.h> /* UINT_MAX */ | |
1c529063 | 5 | #include <linux/mount.h> |
ff0b16a9 EP |
6 | #include <linux/types.h> |
7 | ||
8 | #include "fanotify.h" | |
9 | ||
767cd46c EP |
10 | static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new) |
11 | { | |
12 | pr_debug("%s: old=%p new=%p\n", __func__, old, new); | |
13 | ||
32c32632 AG |
14 | if (old->to_tell == new->to_tell && |
15 | old->data_type == new->data_type && | |
16 | old->tgid == new->tgid) { | |
767cd46c EP |
17 | switch (old->data_type) { |
18 | case (FSNOTIFY_EVENT_PATH): | |
19 | if ((old->path.mnt == new->path.mnt) && | |
20 | (old->path.dentry == new->path.dentry)) | |
21 | return true; | |
22 | case (FSNOTIFY_EVENT_NONE): | |
23 | return true; | |
24 | default: | |
25 | BUG(); | |
26 | }; | |
27 | } | |
28 | return false; | |
29 | } | |
30 | ||
31 | static int fanotify_merge(struct list_head *list, struct fsnotify_event *event) | |
32 | { | |
a12a7dd3 | 33 | struct fsnotify_event_holder *test_holder; |
767cd46c | 34 | struct fsnotify_event *test_event; |
a12a7dd3 EP |
35 | struct fsnotify_event *new_event; |
36 | int ret = 0; | |
767cd46c EP |
37 | |
38 | pr_debug("%s: list=%p event=%p\n", __func__, list, event); | |
39 | ||
40 | /* and the list better be locked by something too! */ | |
41 | ||
a12a7dd3 EP |
42 | list_for_each_entry_reverse(test_holder, list, event_list) { |
43 | test_event = test_holder->event; | |
44 | if (should_merge(test_event, event)) { | |
45 | ret = -EEXIST; | |
46 | ||
47 | /* if they are exactly the same we are done */ | |
48 | if (test_event->mask == event->mask) | |
49 | goto out; | |
50 | ||
9dced01a EP |
51 | /* |
52 | * if the refcnt == 1 this is the only queue | |
53 | * for this event and so we can update the mask | |
54 | * in place. | |
55 | */ | |
56 | if (atomic_read(&test_event->refcnt) == 1) { | |
57 | test_event->mask |= event->mask; | |
58 | goto out; | |
59 | } | |
60 | ||
a12a7dd3 EP |
61 | /* can't allocate memory, merge was no possible */ |
62 | new_event = fsnotify_clone_event(test_event); | |
63 | if (unlikely(!new_event)) { | |
64 | ret = 0; | |
65 | goto out; | |
66 | } | |
767cd46c | 67 | |
a12a7dd3 EP |
68 | /* build new event and replace it on the list */ |
69 | new_event->mask = (test_event->mask | event->mask); | |
70 | fsnotify_replace_event(test_holder, new_event); | |
71 | /* match ref from fsnotify_clone_event() */ | |
72 | fsnotify_put_event(new_event); | |
73 | ||
74 | break; | |
75 | } | |
76 | } | |
77 | out: | |
78 | return ret; | |
767cd46c EP |
79 | } |
80 | ||
ff0b16a9 EP |
81 | static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event) |
82 | { | |
83 | int ret; | |
84 | ||
85 | ||
86 | BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS); | |
87 | BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY); | |
88 | BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); | |
89 | BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE); | |
90 | BUILD_BUG_ON(FAN_OPEN != FS_OPEN); | |
91 | BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD); | |
92 | BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW); | |
93 | ||
94 | pr_debug("%s: group=%p event=%p\n", __func__, group, event); | |
95 | ||
767cd46c EP |
96 | ret = fsnotify_add_notify_event(group, event, NULL, fanotify_merge); |
97 | /* -EEXIST means this event was merged with another, not that it was an error */ | |
98 | if (ret == -EEXIST) | |
99 | ret = 0; | |
ff0b16a9 EP |
100 | return ret; |
101 | } | |
102 | ||
1c529063 EP |
103 | static bool should_send_vfsmount_event(struct fsnotify_group *group, struct vfsmount *mnt, |
104 | __u32 mask) | |
ff0b16a9 EP |
105 | { |
106 | struct fsnotify_mark *fsn_mark; | |
107 | bool send; | |
108 | ||
1c529063 EP |
109 | pr_debug("%s: group=%p vfsmount=%p mask=%x\n", |
110 | __func__, group, mnt, mask); | |
ff0b16a9 | 111 | |
1c529063 EP |
112 | fsn_mark = fsnotify_find_vfsmount_mark(group, mnt); |
113 | if (!fsn_mark) | |
ff0b16a9 EP |
114 | return false; |
115 | ||
1c529063 EP |
116 | send = (mask & fsn_mark->mask); |
117 | ||
118 | /* find took a reference */ | |
119 | fsnotify_put_mark(fsn_mark); | |
120 | ||
121 | return send; | |
122 | } | |
123 | ||
124 | static bool should_send_inode_event(struct fsnotify_group *group, struct inode *inode, | |
125 | __u32 mask) | |
126 | { | |
127 | struct fsnotify_mark *fsn_mark; | |
128 | bool send; | |
129 | ||
130 | pr_debug("%s: group=%p inode=%p mask=%x\n", | |
131 | __func__, group, inode, mask); | |
ff0b16a9 | 132 | |
5444e298 | 133 | fsn_mark = fsnotify_find_inode_mark(group, inode); |
ff0b16a9 EP |
134 | if (!fsn_mark) |
135 | return false; | |
136 | ||
137 | /* if the event is for a child and this inode doesn't care about | |
138 | * events on the child, don't send it! */ | |
139 | if ((mask & FS_EVENT_ON_CHILD) && | |
140 | !(fsn_mark->mask & FS_EVENT_ON_CHILD)) { | |
141 | send = false; | |
142 | } else { | |
143 | /* | |
144 | * We care about children, but do we care about this particular | |
145 | * type of event? | |
146 | */ | |
147 | mask = (mask & ~FS_EVENT_ON_CHILD); | |
148 | send = (fsn_mark->mask & mask); | |
149 | } | |
150 | ||
151 | /* find took a reference */ | |
152 | fsnotify_put_mark(fsn_mark); | |
153 | ||
154 | return send; | |
155 | } | |
156 | ||
1c529063 EP |
157 | static bool fanotify_should_send_event(struct fsnotify_group *group, struct inode *to_tell, |
158 | struct vfsmount *mnt, __u32 mask, void *data, | |
159 | int data_type) | |
160 | { | |
161 | pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x data=%p data_type=%d\n", | |
162 | __func__, group, to_tell, mnt, mask, data, data_type); | |
163 | ||
164 | /* sorry, fanotify only gives a damn about files and dirs */ | |
165 | if (!S_ISREG(to_tell->i_mode) && | |
166 | !S_ISDIR(to_tell->i_mode)) | |
167 | return false; | |
168 | ||
169 | /* if we don't have enough info to send an event to userspace say no */ | |
170 | if (data_type != FSNOTIFY_EVENT_PATH) | |
171 | return false; | |
172 | ||
173 | if (mnt) | |
174 | return should_send_vfsmount_event(group, mnt, mask); | |
175 | else | |
176 | return should_send_inode_event(group, to_tell, mask); | |
177 | } | |
178 | ||
ff0b16a9 EP |
179 | const struct fsnotify_ops fanotify_fsnotify_ops = { |
180 | .handle_event = fanotify_handle_event, | |
181 | .should_send_event = fanotify_should_send_event, | |
182 | .free_group_priv = NULL, | |
183 | .free_event_priv = NULL, | |
184 | .freeing_mark = NULL, | |
185 | }; |