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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> |
5b825c3a | 9 | #include <linux/sched/user.h> |
ff0b16a9 | 10 | #include <linux/types.h> |
9e66e423 | 11 | #include <linux/wait.h> |
ff0b16a9 | 12 | |
7053aee2 JK |
13 | #include "fanotify.h" |
14 | ||
15 | static bool should_merge(struct fsnotify_event *old_fsn, | |
16 | struct fsnotify_event *new_fsn) | |
767cd46c | 17 | { |
7053aee2 | 18 | struct fanotify_event_info *old, *new; |
767cd46c | 19 | |
7053aee2 JK |
20 | pr_debug("%s: old=%p new=%p\n", __func__, old_fsn, new_fsn); |
21 | old = FANOTIFY_E(old_fsn); | |
22 | new = FANOTIFY_E(new_fsn); | |
23 | ||
24 | if (old_fsn->inode == new_fsn->inode && old->tgid == new->tgid && | |
25 | old->path.mnt == new->path.mnt && | |
26 | old->path.dentry == new->path.dentry) | |
27 | return true; | |
767cd46c EP |
28 | return false; |
29 | } | |
30 | ||
f70ab54c | 31 | /* and the list better be locked by something too! */ |
83c0e1b4 | 32 | static int fanotify_merge(struct list_head *list, struct fsnotify_event *event) |
767cd46c | 33 | { |
7053aee2 | 34 | struct fsnotify_event *test_event; |
767cd46c EP |
35 | |
36 | pr_debug("%s: list=%p event=%p\n", __func__, list, event); | |
37 | ||
13116dfd JK |
38 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS |
39 | /* | |
40 | * Don't merge a permission event with any other event so that we know | |
41 | * the event structure we have created in fanotify_handle_event() is the | |
42 | * one we should check for permission response. | |
43 | */ | |
44 | if (event->mask & FAN_ALL_PERM_EVENTS) | |
83c0e1b4 | 45 | return 0; |
13116dfd JK |
46 | #endif |
47 | ||
7053aee2 JK |
48 | list_for_each_entry_reverse(test_event, list, list) { |
49 | if (should_merge(test_event, event)) { | |
6c71100d KM |
50 | test_event->mask |= event->mask; |
51 | return 1; | |
a12a7dd3 EP |
52 | } |
53 | } | |
f70ab54c | 54 | |
6c71100d | 55 | return 0; |
767cd46c EP |
56 | } |
57 | ||
9e66e423 | 58 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS |
f083441b | 59 | static int fanotify_get_response(struct fsnotify_group *group, |
05f0e387 JK |
60 | struct fanotify_perm_event_info *event, |
61 | struct fsnotify_iter_info *iter_info) | |
9e66e423 EP |
62 | { |
63 | int ret; | |
64 | ||
65 | pr_debug("%s: group=%p event=%p\n", __func__, group, event); | |
66 | ||
05f0e387 JK |
67 | /* |
68 | * fsnotify_prepare_user_wait() fails if we race with mark deletion. | |
69 | * Just let the operation pass in that case. | |
70 | */ | |
71 | if (!fsnotify_prepare_user_wait(iter_info)) { | |
72 | event->response = FAN_ALLOW; | |
73 | goto out; | |
74 | } | |
75 | ||
96d41019 | 76 | wait_event(group->fanotify_data.access_waitq, event->response); |
9e66e423 | 77 | |
05f0e387 JK |
78 | fsnotify_finish_user_wait(iter_info); |
79 | out: | |
9e66e423 | 80 | /* userspace responded, convert to something usable */ |
9e66e423 EP |
81 | switch (event->response) { |
82 | case FAN_ALLOW: | |
83 | ret = 0; | |
84 | break; | |
85 | case FAN_DENY: | |
86 | default: | |
87 | ret = -EPERM; | |
88 | } | |
89 | event->response = 0; | |
9e66e423 | 90 | |
b2d87909 EP |
91 | pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__, |
92 | group, event, ret); | |
93 | ||
9e66e423 EP |
94 | return ret; |
95 | } | |
96 | #endif | |
97 | ||
83c4c4b0 | 98 | static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark, |
1968f5ee | 99 | struct fsnotify_mark *vfsmnt_mark, |
83c4c4b0 | 100 | u32 event_mask, |
3cd5eca8 | 101 | const void *data, int data_type) |
1c529063 | 102 | { |
1968f5ee | 103 | __u32 marks_mask, marks_ignored_mask; |
3cd5eca8 | 104 | const struct path *path = data; |
1968f5ee | 105 | |
83c4c4b0 JK |
106 | pr_debug("%s: inode_mark=%p vfsmnt_mark=%p mask=%x data=%p" |
107 | " data_type=%d\n", __func__, inode_mark, vfsmnt_mark, | |
108 | event_mask, data, data_type); | |
1968f5ee | 109 | |
1c529063 | 110 | /* if we don't have enough info to send an event to userspace say no */ |
2069601b | 111 | if (data_type != FSNOTIFY_EVENT_PATH) |
1c529063 EP |
112 | return false; |
113 | ||
e1c048ba | 114 | /* sorry, fanotify only gives a damn about files and dirs */ |
e36cb0b8 | 115 | if (!d_is_reg(path->dentry) && |
54f2a2f4 | 116 | !d_can_lookup(path->dentry)) |
e1c048ba EP |
117 | return false; |
118 | ||
1968f5ee EP |
119 | if (inode_mark && vfsmnt_mark) { |
120 | marks_mask = (vfsmnt_mark->mask | inode_mark->mask); | |
121 | marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask); | |
122 | } else if (inode_mark) { | |
123 | /* | |
124 | * if the event is for a child and this inode doesn't care about | |
125 | * events on the child, don't send it! | |
126 | */ | |
127 | if ((event_mask & FS_EVENT_ON_CHILD) && | |
128 | !(inode_mark->mask & FS_EVENT_ON_CHILD)) | |
129 | return false; | |
130 | marks_mask = inode_mark->mask; | |
131 | marks_ignored_mask = inode_mark->ignored_mask; | |
132 | } else if (vfsmnt_mark) { | |
133 | marks_mask = vfsmnt_mark->mask; | |
134 | marks_ignored_mask = vfsmnt_mark->ignored_mask; | |
135 | } else { | |
136 | BUG(); | |
137 | } | |
138 | ||
e36cb0b8 | 139 | if (d_is_dir(path->dentry) && |
66ba93c0 | 140 | !(marks_mask & FS_ISDIR & ~marks_ignored_mask)) |
8fcd6528 EP |
141 | return false; |
142 | ||
b3c1030d SP |
143 | if (event_mask & FAN_ALL_OUTGOING_EVENTS & marks_mask & |
144 | ~marks_ignored_mask) | |
1968f5ee EP |
145 | return true; |
146 | ||
147 | return false; | |
1c529063 EP |
148 | } |
149 | ||
f083441b | 150 | struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask, |
3cd5eca8 | 151 | const struct path *path) |
f083441b JK |
152 | { |
153 | struct fanotify_event_info *event; | |
154 | ||
155 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS | |
156 | if (mask & FAN_ALL_PERM_EVENTS) { | |
157 | struct fanotify_perm_event_info *pevent; | |
158 | ||
159 | pevent = kmem_cache_alloc(fanotify_perm_event_cachep, | |
160 | GFP_KERNEL); | |
161 | if (!pevent) | |
162 | return NULL; | |
163 | event = &pevent->fae; | |
164 | pevent->response = 0; | |
165 | goto init; | |
166 | } | |
167 | #endif | |
168 | event = kmem_cache_alloc(fanotify_event_cachep, GFP_KERNEL); | |
169 | if (!event) | |
170 | return NULL; | |
171 | init: __maybe_unused | |
172 | fsnotify_init_event(&event->fse, inode, mask); | |
173 | event->tgid = get_pid(task_tgid(current)); | |
174 | if (path) { | |
175 | event->path = *path; | |
176 | path_get(&event->path); | |
177 | } else { | |
178 | event->path.mnt = NULL; | |
179 | event->path.dentry = NULL; | |
180 | } | |
181 | return event; | |
182 | } | |
183 | ||
7053aee2 JK |
184 | static int fanotify_handle_event(struct fsnotify_group *group, |
185 | struct inode *inode, | |
186 | struct fsnotify_mark *inode_mark, | |
187 | struct fsnotify_mark *fanotify_mark, | |
3cd5eca8 | 188 | u32 mask, const void *data, int data_type, |
9385a84d JK |
189 | const unsigned char *file_name, u32 cookie, |
190 | struct fsnotify_iter_info *iter_info) | |
7053aee2 JK |
191 | { |
192 | int ret = 0; | |
193 | struct fanotify_event_info *event; | |
194 | struct fsnotify_event *fsn_event; | |
7053aee2 JK |
195 | |
196 | BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS); | |
197 | BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY); | |
198 | BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); | |
199 | BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE); | |
200 | BUILD_BUG_ON(FAN_OPEN != FS_OPEN); | |
201 | BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD); | |
202 | BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW); | |
203 | BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM); | |
204 | BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM); | |
205 | BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR); | |
206 | ||
83c4c4b0 JK |
207 | if (!fanotify_should_send_event(inode_mark, fanotify_mark, mask, data, |
208 | data_type)) | |
209 | return 0; | |
210 | ||
7053aee2 JK |
211 | pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode, |
212 | mask); | |
213 | ||
f083441b | 214 | event = fanotify_alloc_event(inode, mask, data); |
7053aee2 JK |
215 | if (unlikely(!event)) |
216 | return -ENOMEM; | |
217 | ||
218 | fsn_event = &event->fse; | |
8ba8fa91 | 219 | ret = fsnotify_add_event(group, fsn_event, fanotify_merge); |
83c0e1b4 | 220 | if (ret) { |
482ef06c JK |
221 | /* Permission events shouldn't be merged */ |
222 | BUG_ON(ret == 1 && mask & FAN_ALL_PERM_EVENTS); | |
7053aee2 JK |
223 | /* Our event wasn't used in the end. Free it. */ |
224 | fsnotify_destroy_event(group, fsn_event); | |
482ef06c JK |
225 | |
226 | return 0; | |
7053aee2 JK |
227 | } |
228 | ||
229 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS | |
85816794 | 230 | if (mask & FAN_ALL_PERM_EVENTS) { |
05f0e387 JK |
231 | ret = fanotify_get_response(group, FANOTIFY_PE(fsn_event), |
232 | iter_info); | |
85816794 JK |
233 | fsnotify_destroy_event(group, fsn_event); |
234 | } | |
7053aee2 JK |
235 | #endif |
236 | return ret; | |
237 | } | |
238 | ||
4afeff85 EP |
239 | static void fanotify_free_group_priv(struct fsnotify_group *group) |
240 | { | |
241 | struct user_struct *user; | |
242 | ||
243 | user = group->fanotify_data.user; | |
244 | atomic_dec(&user->fanotify_listeners); | |
245 | free_uid(user); | |
246 | } | |
247 | ||
7053aee2 JK |
248 | static void fanotify_free_event(struct fsnotify_event *fsn_event) |
249 | { | |
250 | struct fanotify_event_info *event; | |
251 | ||
252 | event = FANOTIFY_E(fsn_event); | |
253 | path_put(&event->path); | |
254 | put_pid(event->tgid); | |
f083441b JK |
255 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS |
256 | if (fsn_event->mask & FAN_ALL_PERM_EVENTS) { | |
257 | kmem_cache_free(fanotify_perm_event_cachep, | |
258 | FANOTIFY_PE(fsn_event)); | |
259 | return; | |
260 | } | |
261 | #endif | |
7053aee2 JK |
262 | kmem_cache_free(fanotify_event_cachep, event); |
263 | } | |
264 | ||
054c636e JK |
265 | static void fanotify_free_mark(struct fsnotify_mark *fsn_mark) |
266 | { | |
267 | kmem_cache_free(fanotify_mark_cache, fsn_mark); | |
268 | } | |
269 | ||
ff0b16a9 EP |
270 | const struct fsnotify_ops fanotify_fsnotify_ops = { |
271 | .handle_event = fanotify_handle_event, | |
4afeff85 | 272 | .free_group_priv = fanotify_free_group_priv, |
7053aee2 | 273 | .free_event = fanotify_free_event, |
054c636e | 274 | .free_mark = fanotify_free_mark, |
ff0b16a9 | 275 | }; |