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 | |
7053aee2 JK |
12 | #include "fanotify.h" |
13 | ||
14 | static bool should_merge(struct fsnotify_event *old_fsn, | |
15 | struct fsnotify_event *new_fsn) | |
767cd46c | 16 | { |
7053aee2 | 17 | struct fanotify_event_info *old, *new; |
767cd46c | 18 | |
7053aee2 JK |
19 | pr_debug("%s: old=%p new=%p\n", __func__, old_fsn, new_fsn); |
20 | old = FANOTIFY_E(old_fsn); | |
21 | new = FANOTIFY_E(new_fsn); | |
22 | ||
23 | if (old_fsn->inode == new_fsn->inode && old->tgid == new->tgid && | |
24 | old->path.mnt == new->path.mnt && | |
25 | old->path.dentry == new->path.dentry) | |
26 | return true; | |
767cd46c EP |
27 | return false; |
28 | } | |
29 | ||
f70ab54c | 30 | /* and the list better be locked by something too! */ |
83c0e1b4 | 31 | static int fanotify_merge(struct list_head *list, struct fsnotify_event *event) |
767cd46c | 32 | { |
7053aee2 JK |
33 | struct fsnotify_event *test_event; |
34 | bool do_merge = false; | |
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)) { | |
50 | do_merge = true; | |
a12a7dd3 EP |
51 | break; |
52 | } | |
53 | } | |
f70ab54c | 54 | |
7053aee2 | 55 | if (!do_merge) |
83c0e1b4 | 56 | return 0; |
f70ab54c | 57 | |
7053aee2 | 58 | test_event->mask |= event->mask; |
83c0e1b4 | 59 | return 1; |
767cd46c EP |
60 | } |
61 | ||
9e66e423 | 62 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS |
f083441b JK |
63 | static int fanotify_get_response(struct fsnotify_group *group, |
64 | struct fanotify_perm_event_info *event) | |
9e66e423 EP |
65 | { |
66 | int ret; | |
67 | ||
68 | pr_debug("%s: group=%p event=%p\n", __func__, group, event); | |
69 | ||
09e5f14e LS |
70 | wait_event(group->fanotify_data.access_waitq, event->response || |
71 | atomic_read(&group->fanotify_data.bypass_perm)); | |
72 | ||
5838d444 JK |
73 | if (!event->response) { /* bypass_perm set */ |
74 | /* | |
75 | * Event was canceled because group is being destroyed. Remove | |
76 | * it from group's event list because we are responsible for | |
77 | * freeing the permission event. | |
78 | */ | |
79 | fsnotify_remove_event(group, &event->fae.fse); | |
09e5f14e | 80 | return 0; |
5838d444 | 81 | } |
9e66e423 EP |
82 | |
83 | /* userspace responded, convert to something usable */ | |
9e66e423 EP |
84 | switch (event->response) { |
85 | case FAN_ALLOW: | |
86 | ret = 0; | |
87 | break; | |
88 | case FAN_DENY: | |
89 | default: | |
90 | ret = -EPERM; | |
91 | } | |
92 | event->response = 0; | |
9e66e423 | 93 | |
b2d87909 EP |
94 | pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__, |
95 | group, event, ret); | |
96 | ||
9e66e423 EP |
97 | return ret; |
98 | } | |
99 | #endif | |
100 | ||
83c4c4b0 | 101 | static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark, |
1968f5ee | 102 | struct fsnotify_mark *vfsmnt_mark, |
83c4c4b0 JK |
103 | u32 event_mask, |
104 | void *data, int data_type) | |
1c529063 | 105 | { |
1968f5ee | 106 | __u32 marks_mask, marks_ignored_mask; |
e1c048ba | 107 | struct path *path = data; |
1968f5ee | 108 | |
83c4c4b0 JK |
109 | pr_debug("%s: inode_mark=%p vfsmnt_mark=%p mask=%x data=%p" |
110 | " data_type=%d\n", __func__, inode_mark, vfsmnt_mark, | |
111 | event_mask, data, data_type); | |
1968f5ee | 112 | |
1c529063 | 113 | /* if we don't have enough info to send an event to userspace say no */ |
2069601b | 114 | if (data_type != FSNOTIFY_EVENT_PATH) |
1c529063 EP |
115 | return false; |
116 | ||
e1c048ba | 117 | /* sorry, fanotify only gives a damn about files and dirs */ |
e36cb0b8 DH |
118 | if (!d_is_reg(path->dentry) && |
119 | !d_is_dir(path->dentry)) | |
e1c048ba EP |
120 | return false; |
121 | ||
1968f5ee EP |
122 | if (inode_mark && vfsmnt_mark) { |
123 | marks_mask = (vfsmnt_mark->mask | inode_mark->mask); | |
124 | marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask); | |
125 | } else if (inode_mark) { | |
126 | /* | |
127 | * if the event is for a child and this inode doesn't care about | |
128 | * events on the child, don't send it! | |
129 | */ | |
130 | if ((event_mask & FS_EVENT_ON_CHILD) && | |
131 | !(inode_mark->mask & FS_EVENT_ON_CHILD)) | |
132 | return false; | |
133 | marks_mask = inode_mark->mask; | |
134 | marks_ignored_mask = inode_mark->ignored_mask; | |
135 | } else if (vfsmnt_mark) { | |
136 | marks_mask = vfsmnt_mark->mask; | |
137 | marks_ignored_mask = vfsmnt_mark->ignored_mask; | |
138 | } else { | |
139 | BUG(); | |
140 | } | |
141 | ||
e36cb0b8 | 142 | if (d_is_dir(path->dentry) && |
66ba93c0 | 143 | !(marks_mask & FS_ISDIR & ~marks_ignored_mask)) |
8fcd6528 EP |
144 | return false; |
145 | ||
1968f5ee EP |
146 | if (event_mask & marks_mask & ~marks_ignored_mask) |
147 | return true; | |
148 | ||
149 | return false; | |
1c529063 EP |
150 | } |
151 | ||
f083441b JK |
152 | struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask, |
153 | struct path *path) | |
154 | { | |
155 | struct fanotify_event_info *event; | |
156 | ||
157 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS | |
158 | if (mask & FAN_ALL_PERM_EVENTS) { | |
159 | struct fanotify_perm_event_info *pevent; | |
160 | ||
161 | pevent = kmem_cache_alloc(fanotify_perm_event_cachep, | |
162 | GFP_KERNEL); | |
163 | if (!pevent) | |
164 | return NULL; | |
165 | event = &pevent->fae; | |
166 | pevent->response = 0; | |
167 | goto init; | |
168 | } | |
169 | #endif | |
170 | event = kmem_cache_alloc(fanotify_event_cachep, GFP_KERNEL); | |
171 | if (!event) | |
172 | return NULL; | |
173 | init: __maybe_unused | |
174 | fsnotify_init_event(&event->fse, inode, mask); | |
175 | event->tgid = get_pid(task_tgid(current)); | |
176 | if (path) { | |
177 | event->path = *path; | |
178 | path_get(&event->path); | |
179 | } else { | |
180 | event->path.mnt = NULL; | |
181 | event->path.dentry = NULL; | |
182 | } | |
183 | return event; | |
184 | } | |
185 | ||
7053aee2 JK |
186 | static int fanotify_handle_event(struct fsnotify_group *group, |
187 | struct inode *inode, | |
188 | struct fsnotify_mark *inode_mark, | |
189 | struct fsnotify_mark *fanotify_mark, | |
190 | u32 mask, void *data, int data_type, | |
45a22f4c | 191 | const unsigned char *file_name, u32 cookie) |
7053aee2 JK |
192 | { |
193 | int ret = 0; | |
194 | struct fanotify_event_info *event; | |
195 | struct fsnotify_event *fsn_event; | |
7053aee2 JK |
196 | |
197 | BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS); | |
198 | BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY); | |
199 | BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); | |
200 | BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE); | |
201 | BUILD_BUG_ON(FAN_OPEN != FS_OPEN); | |
202 | BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD); | |
203 | BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW); | |
204 | BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM); | |
205 | BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM); | |
206 | BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR); | |
207 | ||
83c4c4b0 JK |
208 | if (!fanotify_should_send_event(inode_mark, fanotify_mark, mask, data, |
209 | data_type)) | |
210 | return 0; | |
211 | ||
7053aee2 JK |
212 | pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode, |
213 | mask); | |
214 | ||
f083441b | 215 | event = fanotify_alloc_event(inode, mask, data); |
7053aee2 JK |
216 | if (unlikely(!event)) |
217 | return -ENOMEM; | |
218 | ||
219 | fsn_event = &event->fse; | |
8ba8fa91 | 220 | ret = fsnotify_add_event(group, fsn_event, fanotify_merge); |
83c0e1b4 | 221 | if (ret) { |
482ef06c JK |
222 | /* Permission events shouldn't be merged */ |
223 | BUG_ON(ret == 1 && mask & FAN_ALL_PERM_EVENTS); | |
7053aee2 JK |
224 | /* Our event wasn't used in the end. Free it. */ |
225 | fsnotify_destroy_event(group, fsn_event); | |
482ef06c JK |
226 | |
227 | return 0; | |
7053aee2 JK |
228 | } |
229 | ||
230 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS | |
85816794 | 231 | if (mask & FAN_ALL_PERM_EVENTS) { |
f083441b | 232 | ret = fanotify_get_response(group, FANOTIFY_PE(fsn_event)); |
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 | ||
ff0b16a9 EP |
265 | const struct fsnotify_ops fanotify_fsnotify_ops = { |
266 | .handle_event = fanotify_handle_event, | |
4afeff85 | 267 | .free_group_priv = fanotify_free_group_priv, |
7053aee2 | 268 | .free_event = fanotify_free_event, |
ff0b16a9 | 269 | }; |