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Commit | Line | Data |
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33d3dfff | 1 | #include <linux/fanotify.h> |
ff0b16a9 EP |
2 | #include <linux/fdtable.h> |
3 | #include <linux/fsnotify_backend.h> | |
4 | #include <linux/init.h> | |
9e66e423 | 5 | #include <linux/jiffies.h> |
ff0b16a9 | 6 | #include <linux/kernel.h> /* UINT_MAX */ |
1c529063 | 7 | #include <linux/mount.h> |
9e66e423 | 8 | #include <linux/sched.h> |
ff0b16a9 | 9 | #include <linux/types.h> |
9e66e423 | 10 | #include <linux/wait.h> |
ff0b16a9 | 11 | |
767cd46c EP |
12 | static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new) |
13 | { | |
14 | pr_debug("%s: old=%p new=%p\n", __func__, old, new); | |
15 | ||
32c32632 AG |
16 | if (old->to_tell == new->to_tell && |
17 | old->data_type == new->data_type && | |
18 | old->tgid == new->tgid) { | |
767cd46c EP |
19 | switch (old->data_type) { |
20 | case (FSNOTIFY_EVENT_PATH): | |
21 | if ((old->path.mnt == new->path.mnt) && | |
22 | (old->path.dentry == new->path.dentry)) | |
23 | return true; | |
24 | case (FSNOTIFY_EVENT_NONE): | |
25 | return true; | |
26 | default: | |
27 | BUG(); | |
28 | }; | |
29 | } | |
30 | return false; | |
31 | } | |
32 | ||
43ed7e16 | 33 | /* Note, if we return an event in *arg that a reference is being held... */ |
6e5f77b3 EP |
34 | static int fanotify_merge(struct list_head *list, |
35 | struct fsnotify_event *event, | |
36 | void **arg) | |
767cd46c | 37 | { |
a12a7dd3 | 38 | struct fsnotify_event_holder *test_holder; |
767cd46c | 39 | struct fsnotify_event *test_event; |
a12a7dd3 | 40 | struct fsnotify_event *new_event; |
43ed7e16 | 41 | struct fsnotify_event **return_event = (struct fsnotify_event **)arg; |
a12a7dd3 | 42 | int ret = 0; |
767cd46c EP |
43 | |
44 | pr_debug("%s: list=%p event=%p\n", __func__, list, event); | |
45 | ||
43ed7e16 EP |
46 | *return_event = NULL; |
47 | ||
767cd46c EP |
48 | /* and the list better be locked by something too! */ |
49 | ||
a12a7dd3 EP |
50 | list_for_each_entry_reverse(test_holder, list, event_list) { |
51 | test_event = test_holder->event; | |
52 | if (should_merge(test_event, event)) { | |
43ed7e16 EP |
53 | fsnotify_get_event(test_event); |
54 | *return_event = test_event; | |
a12a7dd3 | 55 | |
43ed7e16 | 56 | ret = -EEXIST; |
a12a7dd3 EP |
57 | /* if they are exactly the same we are done */ |
58 | if (test_event->mask == event->mask) | |
59 | goto out; | |
60 | ||
9dced01a EP |
61 | /* |
62 | * if the refcnt == 1 this is the only queue | |
63 | * for this event and so we can update the mask | |
64 | * in place. | |
65 | */ | |
66 | if (atomic_read(&test_event->refcnt) == 1) { | |
67 | test_event->mask |= event->mask; | |
68 | goto out; | |
69 | } | |
70 | ||
a12a7dd3 EP |
71 | /* can't allocate memory, merge was no possible */ |
72 | new_event = fsnotify_clone_event(test_event); | |
73 | if (unlikely(!new_event)) { | |
74 | ret = 0; | |
75 | goto out; | |
76 | } | |
767cd46c | 77 | |
43ed7e16 EP |
78 | /* we didn't return the test_event, so drop that ref */ |
79 | fsnotify_put_event(test_event); | |
80 | /* the reference we return on new_event is from clone */ | |
81 | *return_event = new_event; | |
82 | ||
a12a7dd3 EP |
83 | /* build new event and replace it on the list */ |
84 | new_event->mask = (test_event->mask | event->mask); | |
85 | fsnotify_replace_event(test_holder, new_event); | |
a12a7dd3 EP |
86 | |
87 | break; | |
88 | } | |
89 | } | |
90 | out: | |
91 | return ret; | |
767cd46c EP |
92 | } |
93 | ||
9e66e423 EP |
94 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS |
95 | static int fanotify_get_response_from_access(struct fsnotify_group *group, | |
96 | struct fsnotify_event *event) | |
97 | { | |
98 | int ret; | |
99 | ||
100 | pr_debug("%s: group=%p event=%p\n", __func__, group, event); | |
101 | ||
102 | wait_event(group->fanotify_data.access_waitq, event->response); | |
103 | ||
104 | /* userspace responded, convert to something usable */ | |
105 | spin_lock(&event->lock); | |
106 | switch (event->response) { | |
107 | case FAN_ALLOW: | |
108 | ret = 0; | |
109 | break; | |
110 | case FAN_DENY: | |
111 | default: | |
112 | ret = -EPERM; | |
113 | } | |
114 | event->response = 0; | |
115 | spin_unlock(&event->lock); | |
116 | ||
117 | return ret; | |
118 | } | |
119 | #endif | |
120 | ||
ff0b16a9 EP |
121 | static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event) |
122 | { | |
123 | int ret; | |
9e66e423 | 124 | struct fsnotify_event *notify_event = NULL; |
ff0b16a9 EP |
125 | |
126 | BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS); | |
127 | BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY); | |
128 | BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); | |
129 | BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE); | |
130 | BUILD_BUG_ON(FAN_OPEN != FS_OPEN); | |
131 | BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD); | |
132 | BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW); | |
9e66e423 EP |
133 | BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM); |
134 | BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM); | |
ff0b16a9 EP |
135 | |
136 | pr_debug("%s: group=%p event=%p\n", __func__, group, event); | |
137 | ||
9e66e423 EP |
138 | ret = fsnotify_add_notify_event(group, event, NULL, fanotify_merge, |
139 | (void **)¬ify_event); | |
767cd46c EP |
140 | /* -EEXIST means this event was merged with another, not that it was an error */ |
141 | if (ret == -EEXIST) | |
142 | ret = 0; | |
9e66e423 EP |
143 | if (ret) |
144 | goto out; | |
145 | ||
146 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS | |
147 | if (event->mask & FAN_ALL_PERM_EVENTS) { | |
148 | /* if we merged we need to wait on the new event */ | |
149 | if (notify_event) | |
150 | event = notify_event; | |
151 | ret = fanotify_get_response_from_access(group, event); | |
152 | } | |
153 | #endif | |
154 | ||
155 | out: | |
156 | if (notify_event) | |
157 | fsnotify_put_event(notify_event); | |
ff0b16a9 EP |
158 | return ret; |
159 | } | |
160 | ||
1c529063 | 161 | static bool should_send_vfsmount_event(struct fsnotify_group *group, struct vfsmount *mnt, |
32a4df13 | 162 | struct inode *inode, __u32 mask) |
ff0b16a9 | 163 | { |
32a4df13 EP |
164 | struct fsnotify_mark *mnt_mark; |
165 | struct fsnotify_mark *inode_mark; | |
ff0b16a9 | 166 | |
1c529063 EP |
167 | pr_debug("%s: group=%p vfsmount=%p mask=%x\n", |
168 | __func__, group, mnt, mask); | |
ff0b16a9 | 169 | |
32a4df13 EP |
170 | mnt_mark = fsnotify_find_vfsmount_mark(group, mnt); |
171 | if (!mnt_mark) | |
ff0b16a9 EP |
172 | return false; |
173 | ||
32a4df13 EP |
174 | mask &= mnt_mark->mask; |
175 | mask &= ~mnt_mark->ignored_mask; | |
176 | ||
177 | if (mask) { | |
178 | inode_mark = fsnotify_find_inode_mark(group, inode); | |
179 | if (inode_mark) { | |
180 | mask &= ~inode_mark->ignored_mask; | |
181 | fsnotify_put_mark(inode_mark); | |
182 | } | |
183 | } | |
1c529063 EP |
184 | |
185 | /* find took a reference */ | |
32a4df13 | 186 | fsnotify_put_mark(mnt_mark); |
1c529063 | 187 | |
32a4df13 | 188 | return mask; |
1c529063 EP |
189 | } |
190 | ||
191 | static bool should_send_inode_event(struct fsnotify_group *group, struct inode *inode, | |
192 | __u32 mask) | |
193 | { | |
194 | struct fsnotify_mark *fsn_mark; | |
1c529063 EP |
195 | |
196 | pr_debug("%s: group=%p inode=%p mask=%x\n", | |
197 | __func__, group, inode, mask); | |
ff0b16a9 | 198 | |
5444e298 | 199 | fsn_mark = fsnotify_find_inode_mark(group, inode); |
ff0b16a9 EP |
200 | if (!fsn_mark) |
201 | return false; | |
202 | ||
203 | /* if the event is for a child and this inode doesn't care about | |
204 | * events on the child, don't send it! */ | |
205 | if ((mask & FS_EVENT_ON_CHILD) && | |
206 | !(fsn_mark->mask & FS_EVENT_ON_CHILD)) { | |
32a4df13 | 207 | mask = 0; |
ff0b16a9 EP |
208 | } else { |
209 | /* | |
210 | * We care about children, but do we care about this particular | |
211 | * type of event? | |
212 | */ | |
32a4df13 EP |
213 | mask &= ~FS_EVENT_ON_CHILD; |
214 | mask &= fsn_mark->mask; | |
215 | mask &= ~fsn_mark->ignored_mask; | |
ff0b16a9 EP |
216 | } |
217 | ||
218 | /* find took a reference */ | |
219 | fsnotify_put_mark(fsn_mark); | |
220 | ||
32a4df13 | 221 | return mask; |
ff0b16a9 EP |
222 | } |
223 | ||
1c529063 EP |
224 | static bool fanotify_should_send_event(struct fsnotify_group *group, struct inode *to_tell, |
225 | struct vfsmount *mnt, __u32 mask, void *data, | |
226 | int data_type) | |
227 | { | |
228 | pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x data=%p data_type=%d\n", | |
229 | __func__, group, to_tell, mnt, mask, data, data_type); | |
230 | ||
231 | /* sorry, fanotify only gives a damn about files and dirs */ | |
232 | if (!S_ISREG(to_tell->i_mode) && | |
233 | !S_ISDIR(to_tell->i_mode)) | |
234 | return false; | |
235 | ||
236 | /* if we don't have enough info to send an event to userspace say no */ | |
237 | if (data_type != FSNOTIFY_EVENT_PATH) | |
238 | return false; | |
239 | ||
240 | if (mnt) | |
32a4df13 | 241 | return should_send_vfsmount_event(group, mnt, to_tell, mask); |
1c529063 EP |
242 | else |
243 | return should_send_inode_event(group, to_tell, mask); | |
244 | } | |
245 | ||
ff0b16a9 EP |
246 | const struct fsnotify_ops fanotify_fsnotify_ops = { |
247 | .handle_event = fanotify_handle_event, | |
248 | .should_send_event = fanotify_should_send_event, | |
249 | .free_group_priv = NULL, | |
250 | .free_event_priv = NULL, | |
251 | .freeing_mark = NULL, | |
252 | }; |