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 | 19 | switch (old->data_type) { |
2069601b | 20 | case (FSNOTIFY_EVENT_PATH): |
03a1cec1 LS |
21 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS |
22 | /* dont merge two permission events */ | |
23 | if ((old->mask & FAN_ALL_PERM_EVENTS) && | |
24 | (new->mask & FAN_ALL_PERM_EVENTS)) | |
25 | return false; | |
26 | #endif | |
2069601b LT |
27 | if ((old->path.mnt == new->path.mnt) && |
28 | (old->path.dentry == new->path.dentry)) | |
767cd46c | 29 | return true; |
848561d3 | 30 | break; |
767cd46c EP |
31 | case (FSNOTIFY_EVENT_NONE): |
32 | return true; | |
33 | default: | |
34 | BUG(); | |
35 | }; | |
36 | } | |
37 | return false; | |
38 | } | |
39 | ||
f70ab54c EP |
40 | /* and the list better be locked by something too! */ |
41 | static struct fsnotify_event *fanotify_merge(struct list_head *list, | |
42 | struct fsnotify_event *event) | |
767cd46c | 43 | { |
a12a7dd3 | 44 | struct fsnotify_event_holder *test_holder; |
f70ab54c | 45 | struct fsnotify_event *test_event = NULL; |
a12a7dd3 | 46 | struct fsnotify_event *new_event; |
767cd46c EP |
47 | |
48 | pr_debug("%s: list=%p event=%p\n", __func__, list, event); | |
49 | ||
767cd46c | 50 | |
a12a7dd3 | 51 | list_for_each_entry_reverse(test_holder, list, event_list) { |
f70ab54c EP |
52 | if (should_merge(test_holder->event, event)) { |
53 | test_event = test_holder->event; | |
a12a7dd3 EP |
54 | break; |
55 | } | |
56 | } | |
f70ab54c EP |
57 | |
58 | if (!test_event) | |
59 | return NULL; | |
60 | ||
61 | fsnotify_get_event(test_event); | |
62 | ||
63 | /* if they are exactly the same we are done */ | |
64 | if (test_event->mask == event->mask) | |
65 | return test_event; | |
66 | ||
67 | /* | |
68 | * if the refcnt == 2 this is the only queue | |
69 | * for this event and so we can update the mask | |
70 | * in place. | |
71 | */ | |
72 | if (atomic_read(&test_event->refcnt) == 2) { | |
73 | test_event->mask |= event->mask; | |
74 | return test_event; | |
75 | } | |
76 | ||
77 | new_event = fsnotify_clone_event(test_event); | |
78 | ||
79 | /* done with test_event */ | |
80 | fsnotify_put_event(test_event); | |
81 | ||
82 | /* couldn't allocate memory, merge was not possible */ | |
83 | if (unlikely(!new_event)) | |
84 | return ERR_PTR(-ENOMEM); | |
85 | ||
86 | /* build new event and replace it on the list */ | |
87 | new_event->mask = (test_event->mask | event->mask); | |
88 | fsnotify_replace_event(test_holder, new_event); | |
89 | ||
90 | /* we hold a reference on new_event from clone_event */ | |
91 | return new_event; | |
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 | ||
09e5f14e LS |
102 | wait_event(group->fanotify_data.access_waitq, event->response || |
103 | atomic_read(&group->fanotify_data.bypass_perm)); | |
104 | ||
105 | if (!event->response) /* bypass_perm set */ | |
106 | return 0; | |
9e66e423 EP |
107 | |
108 | /* userspace responded, convert to something usable */ | |
109 | spin_lock(&event->lock); | |
110 | switch (event->response) { | |
111 | case FAN_ALLOW: | |
112 | ret = 0; | |
113 | break; | |
114 | case FAN_DENY: | |
115 | default: | |
116 | ret = -EPERM; | |
117 | } | |
118 | event->response = 0; | |
119 | spin_unlock(&event->lock); | |
120 | ||
b2d87909 EP |
121 | pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__, |
122 | group, event, ret); | |
123 | ||
9e66e423 EP |
124 | return ret; |
125 | } | |
126 | #endif | |
127 | ||
3a9b16b4 | 128 | static int fanotify_handle_event(struct fsnotify_group *group, |
ce8f76fb EP |
129 | struct fsnotify_mark *inode_mark, |
130 | struct fsnotify_mark *fanotify_mark, | |
3a9b16b4 | 131 | struct fsnotify_event *event) |
ff0b16a9 | 132 | { |
f70ab54c | 133 | int ret = 0; |
9e66e423 | 134 | struct fsnotify_event *notify_event = NULL; |
ff0b16a9 EP |
135 | |
136 | BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS); | |
137 | BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY); | |
138 | BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); | |
139 | BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE); | |
140 | BUILD_BUG_ON(FAN_OPEN != FS_OPEN); | |
141 | BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD); | |
142 | BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW); | |
9e66e423 EP |
143 | BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM); |
144 | BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM); | |
8fcd6528 | 145 | BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR); |
ff0b16a9 EP |
146 | |
147 | pr_debug("%s: group=%p event=%p\n", __func__, group, event); | |
148 | ||
f70ab54c EP |
149 | notify_event = fsnotify_add_notify_event(group, event, NULL, fanotify_merge); |
150 | if (IS_ERR(notify_event)) | |
151 | return PTR_ERR(notify_event); | |
9e66e423 EP |
152 | |
153 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS | |
154 | if (event->mask & FAN_ALL_PERM_EVENTS) { | |
155 | /* if we merged we need to wait on the new event */ | |
156 | if (notify_event) | |
157 | event = notify_event; | |
158 | ret = fanotify_get_response_from_access(group, event); | |
159 | } | |
160 | #endif | |
161 | ||
9e66e423 EP |
162 | if (notify_event) |
163 | fsnotify_put_event(notify_event); | |
f70ab54c | 164 | |
ff0b16a9 EP |
165 | return ret; |
166 | } | |
167 | ||
ce8f76fb EP |
168 | static bool fanotify_should_send_event(struct fsnotify_group *group, |
169 | struct inode *to_tell, | |
ce8f76fb | 170 | struct fsnotify_mark *inode_mark, |
1968f5ee EP |
171 | struct fsnotify_mark *vfsmnt_mark, |
172 | __u32 event_mask, void *data, int data_type) | |
1c529063 | 173 | { |
1968f5ee | 174 | __u32 marks_mask, marks_ignored_mask; |
e1c048ba | 175 | struct path *path = data; |
1968f5ee EP |
176 | |
177 | pr_debug("%s: group=%p to_tell=%p inode_mark=%p vfsmnt_mark=%p " | |
178 | "mask=%x data=%p data_type=%d\n", __func__, group, to_tell, | |
179 | inode_mark, vfsmnt_mark, event_mask, data, data_type); | |
180 | ||
1c529063 | 181 | /* if we don't have enough info to send an event to userspace say no */ |
2069601b | 182 | if (data_type != FSNOTIFY_EVENT_PATH) |
1c529063 EP |
183 | return false; |
184 | ||
e1c048ba EP |
185 | /* sorry, fanotify only gives a damn about files and dirs */ |
186 | if (!S_ISREG(path->dentry->d_inode->i_mode) && | |
187 | !S_ISDIR(path->dentry->d_inode->i_mode)) | |
188 | return false; | |
189 | ||
1968f5ee EP |
190 | if (inode_mark && vfsmnt_mark) { |
191 | marks_mask = (vfsmnt_mark->mask | inode_mark->mask); | |
192 | marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask); | |
193 | } else if (inode_mark) { | |
194 | /* | |
195 | * if the event is for a child and this inode doesn't care about | |
196 | * events on the child, don't send it! | |
197 | */ | |
198 | if ((event_mask & FS_EVENT_ON_CHILD) && | |
199 | !(inode_mark->mask & FS_EVENT_ON_CHILD)) | |
200 | return false; | |
201 | marks_mask = inode_mark->mask; | |
202 | marks_ignored_mask = inode_mark->ignored_mask; | |
203 | } else if (vfsmnt_mark) { | |
204 | marks_mask = vfsmnt_mark->mask; | |
205 | marks_ignored_mask = vfsmnt_mark->ignored_mask; | |
206 | } else { | |
207 | BUG(); | |
208 | } | |
209 | ||
8fcd6528 EP |
210 | if (S_ISDIR(path->dentry->d_inode->i_mode) && |
211 | (marks_ignored_mask & FS_ISDIR)) | |
212 | return false; | |
213 | ||
1968f5ee EP |
214 | if (event_mask & marks_mask & ~marks_ignored_mask) |
215 | return true; | |
216 | ||
217 | return false; | |
1c529063 EP |
218 | } |
219 | ||
4afeff85 EP |
220 | static void fanotify_free_group_priv(struct fsnotify_group *group) |
221 | { | |
222 | struct user_struct *user; | |
223 | ||
224 | user = group->fanotify_data.user; | |
225 | atomic_dec(&user->fanotify_listeners); | |
226 | free_uid(user); | |
227 | } | |
228 | ||
ff0b16a9 EP |
229 | const struct fsnotify_ops fanotify_fsnotify_ops = { |
230 | .handle_event = fanotify_handle_event, | |
231 | .should_send_event = fanotify_should_send_event, | |
4afeff85 | 232 | .free_group_priv = fanotify_free_group_priv, |
ff0b16a9 EP |
233 | .free_event_priv = NULL, |
234 | .freeing_mark = NULL, | |
235 | }; |