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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
33d3dfff | 2 | #include <linux/fanotify.h> |
ff0b16a9 EP |
3 | #include <linux/fdtable.h> |
4 | #include <linux/fsnotify_backend.h> | |
5 | #include <linux/init.h> | |
9e66e423 | 6 | #include <linux/jiffies.h> |
ff0b16a9 | 7 | #include <linux/kernel.h> /* UINT_MAX */ |
1c529063 | 8 | #include <linux/mount.h> |
9e66e423 | 9 | #include <linux/sched.h> |
5b825c3a | 10 | #include <linux/sched/user.h> |
ff0b16a9 | 11 | #include <linux/types.h> |
9e66e423 | 12 | #include <linux/wait.h> |
ff0b16a9 | 13 | |
7053aee2 JK |
14 | #include "fanotify.h" |
15 | ||
16 | static bool should_merge(struct fsnotify_event *old_fsn, | |
17 | struct fsnotify_event *new_fsn) | |
767cd46c | 18 | { |
7053aee2 | 19 | struct fanotify_event_info *old, *new; |
767cd46c | 20 | |
7053aee2 JK |
21 | pr_debug("%s: old=%p new=%p\n", __func__, old_fsn, new_fsn); |
22 | old = FANOTIFY_E(old_fsn); | |
23 | new = FANOTIFY_E(new_fsn); | |
24 | ||
25 | if (old_fsn->inode == new_fsn->inode && old->tgid == new->tgid && | |
26 | old->path.mnt == new->path.mnt && | |
27 | old->path.dentry == new->path.dentry) | |
28 | return true; | |
767cd46c EP |
29 | return false; |
30 | } | |
31 | ||
f70ab54c | 32 | /* and the list better be locked by something too! */ |
83c0e1b4 | 33 | static int fanotify_merge(struct list_head *list, struct fsnotify_event *event) |
767cd46c | 34 | { |
7053aee2 | 35 | struct fsnotify_event *test_event; |
767cd46c EP |
36 | |
37 | pr_debug("%s: list=%p event=%p\n", __func__, list, event); | |
38 | ||
13116dfd JK |
39 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS |
40 | /* | |
41 | * Don't merge a permission event with any other event so that we know | |
42 | * the event structure we have created in fanotify_handle_event() is the | |
43 | * one we should check for permission response. | |
44 | */ | |
45 | if (event->mask & FAN_ALL_PERM_EVENTS) | |
83c0e1b4 | 46 | return 0; |
13116dfd JK |
47 | #endif |
48 | ||
7053aee2 JK |
49 | list_for_each_entry_reverse(test_event, list, list) { |
50 | if (should_merge(test_event, event)) { | |
6c71100d KM |
51 | test_event->mask |= event->mask; |
52 | return 1; | |
a12a7dd3 EP |
53 | } |
54 | } | |
f70ab54c | 55 | |
6c71100d | 56 | return 0; |
767cd46c EP |
57 | } |
58 | ||
9e66e423 | 59 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS |
f083441b | 60 | static int fanotify_get_response(struct fsnotify_group *group, |
05f0e387 JK |
61 | struct fanotify_perm_event_info *event, |
62 | struct fsnotify_iter_info *iter_info) | |
9e66e423 EP |
63 | { |
64 | int ret; | |
65 | ||
66 | pr_debug("%s: group=%p event=%p\n", __func__, group, event); | |
67 | ||
05f0e387 JK |
68 | /* |
69 | * fsnotify_prepare_user_wait() fails if we race with mark deletion. | |
70 | * Just let the operation pass in that case. | |
71 | */ | |
72 | if (!fsnotify_prepare_user_wait(iter_info)) { | |
73 | event->response = FAN_ALLOW; | |
74 | goto out; | |
75 | } | |
76 | ||
96d41019 | 77 | wait_event(group->fanotify_data.access_waitq, event->response); |
9e66e423 | 78 | |
05f0e387 JK |
79 | fsnotify_finish_user_wait(iter_info); |
80 | out: | |
9e66e423 | 81 | /* userspace responded, convert to something usable */ |
9e66e423 EP |
82 | switch (event->response) { |
83 | case FAN_ALLOW: | |
84 | ret = 0; | |
85 | break; | |
86 | case FAN_DENY: | |
87 | default: | |
88 | ret = -EPERM; | |
89 | } | |
90 | event->response = 0; | |
9e66e423 | 91 | |
b2d87909 EP |
92 | pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__, |
93 | group, event, ret); | |
94 | ||
9e66e423 EP |
95 | return ret; |
96 | } | |
97 | #endif | |
98 | ||
83c4c4b0 | 99 | static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark, |
1968f5ee | 100 | struct fsnotify_mark *vfsmnt_mark, |
83c4c4b0 | 101 | u32 event_mask, |
3cd5eca8 | 102 | const void *data, int data_type) |
1c529063 | 103 | { |
1968f5ee | 104 | __u32 marks_mask, marks_ignored_mask; |
3cd5eca8 | 105 | const struct path *path = data; |
1968f5ee | 106 | |
83c4c4b0 JK |
107 | pr_debug("%s: inode_mark=%p vfsmnt_mark=%p mask=%x data=%p" |
108 | " data_type=%d\n", __func__, inode_mark, vfsmnt_mark, | |
109 | event_mask, data, data_type); | |
1968f5ee | 110 | |
1c529063 | 111 | /* if we don't have enough info to send an event to userspace say no */ |
2069601b | 112 | if (data_type != FSNOTIFY_EVENT_PATH) |
1c529063 EP |
113 | return false; |
114 | ||
e1c048ba | 115 | /* sorry, fanotify only gives a damn about files and dirs */ |
e36cb0b8 | 116 | if (!d_is_reg(path->dentry) && |
54f2a2f4 | 117 | !d_can_lookup(path->dentry)) |
e1c048ba EP |
118 | return false; |
119 | ||
1968f5ee EP |
120 | if (inode_mark && vfsmnt_mark) { |
121 | marks_mask = (vfsmnt_mark->mask | inode_mark->mask); | |
122 | marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask); | |
123 | } else if (inode_mark) { | |
124 | /* | |
125 | * if the event is for a child and this inode doesn't care about | |
126 | * events on the child, don't send it! | |
127 | */ | |
128 | if ((event_mask & FS_EVENT_ON_CHILD) && | |
129 | !(inode_mark->mask & FS_EVENT_ON_CHILD)) | |
130 | return false; | |
131 | marks_mask = inode_mark->mask; | |
132 | marks_ignored_mask = inode_mark->ignored_mask; | |
133 | } else if (vfsmnt_mark) { | |
134 | marks_mask = vfsmnt_mark->mask; | |
135 | marks_ignored_mask = vfsmnt_mark->ignored_mask; | |
136 | } else { | |
137 | BUG(); | |
138 | } | |
139 | ||
e36cb0b8 | 140 | if (d_is_dir(path->dentry) && |
66ba93c0 | 141 | !(marks_mask & FS_ISDIR & ~marks_ignored_mask)) |
8fcd6528 EP |
142 | return false; |
143 | ||
b3c1030d SP |
144 | if (event_mask & FAN_ALL_OUTGOING_EVENTS & marks_mask & |
145 | ~marks_ignored_mask) | |
1968f5ee EP |
146 | return true; |
147 | ||
148 | return false; | |
1c529063 EP |
149 | } |
150 | ||
f083441b | 151 | struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask, |
3cd5eca8 | 152 | const struct path *path) |
f083441b JK |
153 | { |
154 | struct fanotify_event_info *event; | |
155 | ||
156 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS | |
157 | if (mask & FAN_ALL_PERM_EVENTS) { | |
158 | struct fanotify_perm_event_info *pevent; | |
159 | ||
160 | pevent = kmem_cache_alloc(fanotify_perm_event_cachep, | |
161 | GFP_KERNEL); | |
162 | if (!pevent) | |
163 | return NULL; | |
164 | event = &pevent->fae; | |
165 | pevent->response = 0; | |
166 | goto init; | |
167 | } | |
168 | #endif | |
169 | event = kmem_cache_alloc(fanotify_event_cachep, GFP_KERNEL); | |
170 | if (!event) | |
171 | return NULL; | |
172 | init: __maybe_unused | |
173 | fsnotify_init_event(&event->fse, inode, mask); | |
174 | event->tgid = get_pid(task_tgid(current)); | |
175 | if (path) { | |
176 | event->path = *path; | |
177 | path_get(&event->path); | |
178 | } else { | |
179 | event->path.mnt = NULL; | |
180 | event->path.dentry = NULL; | |
181 | } | |
182 | return event; | |
183 | } | |
184 | ||
7053aee2 JK |
185 | static int fanotify_handle_event(struct fsnotify_group *group, |
186 | struct inode *inode, | |
187 | struct fsnotify_mark *inode_mark, | |
188 | struct fsnotify_mark *fanotify_mark, | |
3cd5eca8 | 189 | u32 mask, const void *data, int data_type, |
9385a84d JK |
190 | const unsigned char *file_name, u32 cookie, |
191 | struct fsnotify_iter_info *iter_info) | |
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) { |
05f0e387 JK |
232 | ret = fanotify_get_response(group, FANOTIFY_PE(fsn_event), |
233 | iter_info); | |
85816794 JK |
234 | fsnotify_destroy_event(group, fsn_event); |
235 | } | |
7053aee2 JK |
236 | #endif |
237 | return ret; | |
238 | } | |
239 | ||
4afeff85 EP |
240 | static void fanotify_free_group_priv(struct fsnotify_group *group) |
241 | { | |
242 | struct user_struct *user; | |
243 | ||
244 | user = group->fanotify_data.user; | |
245 | atomic_dec(&user->fanotify_listeners); | |
246 | free_uid(user); | |
247 | } | |
248 | ||
7053aee2 JK |
249 | static void fanotify_free_event(struct fsnotify_event *fsn_event) |
250 | { | |
251 | struct fanotify_event_info *event; | |
252 | ||
253 | event = FANOTIFY_E(fsn_event); | |
254 | path_put(&event->path); | |
255 | put_pid(event->tgid); | |
f083441b JK |
256 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS |
257 | if (fsn_event->mask & FAN_ALL_PERM_EVENTS) { | |
258 | kmem_cache_free(fanotify_perm_event_cachep, | |
259 | FANOTIFY_PE(fsn_event)); | |
260 | return; | |
261 | } | |
262 | #endif | |
7053aee2 JK |
263 | kmem_cache_free(fanotify_event_cachep, event); |
264 | } | |
265 | ||
054c636e JK |
266 | static void fanotify_free_mark(struct fsnotify_mark *fsn_mark) |
267 | { | |
268 | kmem_cache_free(fanotify_mark_cache, fsn_mark); | |
269 | } | |
270 | ||
ff0b16a9 EP |
271 | const struct fsnotify_ops fanotify_fsnotify_ops = { |
272 | .handle_event = fanotify_handle_event, | |
4afeff85 | 273 | .free_group_priv = fanotify_free_group_priv, |
7053aee2 | 274 | .free_event = fanotify_free_event, |
054c636e | 275 | .free_mark = fanotify_free_mark, |
ff0b16a9 | 276 | }; |