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 EP |
30 | /* and the list better be locked by something too! */ |
31 | static struct fsnotify_event *fanotify_merge(struct list_head *list, | |
32 | struct fsnotify_event *event) | |
767cd46c | 33 | { |
7053aee2 JK |
34 | struct fsnotify_event *test_event; |
35 | bool do_merge = false; | |
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) | |
46 | return NULL; | |
47 | #endif | |
48 | ||
7053aee2 JK |
49 | list_for_each_entry_reverse(test_event, list, list) { |
50 | if (should_merge(test_event, event)) { | |
51 | do_merge = true; | |
a12a7dd3 EP |
52 | break; |
53 | } | |
54 | } | |
f70ab54c | 55 | |
7053aee2 | 56 | if (!do_merge) |
f70ab54c EP |
57 | return NULL; |
58 | ||
7053aee2 JK |
59 | test_event->mask |= event->mask; |
60 | return test_event; | |
767cd46c EP |
61 | } |
62 | ||
9e66e423 EP |
63 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS |
64 | static int fanotify_get_response_from_access(struct fsnotify_group *group, | |
7053aee2 | 65 | struct fanotify_event_info *event) |
9e66e423 EP |
66 | { |
67 | int ret; | |
68 | ||
69 | pr_debug("%s: group=%p event=%p\n", __func__, group, event); | |
70 | ||
09e5f14e LS |
71 | wait_event(group->fanotify_data.access_waitq, event->response || |
72 | atomic_read(&group->fanotify_data.bypass_perm)); | |
73 | ||
74 | if (!event->response) /* bypass_perm set */ | |
75 | return 0; | |
9e66e423 EP |
76 | |
77 | /* userspace responded, convert to something usable */ | |
9e66e423 EP |
78 | switch (event->response) { |
79 | case FAN_ALLOW: | |
80 | ret = 0; | |
81 | break; | |
82 | case FAN_DENY: | |
83 | default: | |
84 | ret = -EPERM; | |
85 | } | |
86 | event->response = 0; | |
9e66e423 | 87 | |
b2d87909 EP |
88 | pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__, |
89 | group, event, ret); | |
90 | ||
9e66e423 EP |
91 | return ret; |
92 | } | |
93 | #endif | |
94 | ||
83c4c4b0 | 95 | static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark, |
1968f5ee | 96 | struct fsnotify_mark *vfsmnt_mark, |
83c4c4b0 JK |
97 | u32 event_mask, |
98 | void *data, int data_type) | |
1c529063 | 99 | { |
1968f5ee | 100 | __u32 marks_mask, marks_ignored_mask; |
e1c048ba | 101 | struct path *path = data; |
1968f5ee | 102 | |
83c4c4b0 JK |
103 | pr_debug("%s: inode_mark=%p vfsmnt_mark=%p mask=%x data=%p" |
104 | " data_type=%d\n", __func__, inode_mark, vfsmnt_mark, | |
105 | event_mask, data, data_type); | |
1968f5ee | 106 | |
1c529063 | 107 | /* if we don't have enough info to send an event to userspace say no */ |
2069601b | 108 | if (data_type != FSNOTIFY_EVENT_PATH) |
1c529063 EP |
109 | return false; |
110 | ||
e1c048ba EP |
111 | /* sorry, fanotify only gives a damn about files and dirs */ |
112 | if (!S_ISREG(path->dentry->d_inode->i_mode) && | |
113 | !S_ISDIR(path->dentry->d_inode->i_mode)) | |
114 | return false; | |
115 | ||
1968f5ee EP |
116 | if (inode_mark && vfsmnt_mark) { |
117 | marks_mask = (vfsmnt_mark->mask | inode_mark->mask); | |
118 | marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask); | |
119 | } else if (inode_mark) { | |
120 | /* | |
121 | * if the event is for a child and this inode doesn't care about | |
122 | * events on the child, don't send it! | |
123 | */ | |
124 | if ((event_mask & FS_EVENT_ON_CHILD) && | |
125 | !(inode_mark->mask & FS_EVENT_ON_CHILD)) | |
126 | return false; | |
127 | marks_mask = inode_mark->mask; | |
128 | marks_ignored_mask = inode_mark->ignored_mask; | |
129 | } else if (vfsmnt_mark) { | |
130 | marks_mask = vfsmnt_mark->mask; | |
131 | marks_ignored_mask = vfsmnt_mark->ignored_mask; | |
132 | } else { | |
133 | BUG(); | |
134 | } | |
135 | ||
8fcd6528 EP |
136 | if (S_ISDIR(path->dentry->d_inode->i_mode) && |
137 | (marks_ignored_mask & FS_ISDIR)) | |
138 | return false; | |
139 | ||
1968f5ee EP |
140 | if (event_mask & marks_mask & ~marks_ignored_mask) |
141 | return true; | |
142 | ||
143 | return false; | |
1c529063 EP |
144 | } |
145 | ||
7053aee2 JK |
146 | static int fanotify_handle_event(struct fsnotify_group *group, |
147 | struct inode *inode, | |
148 | struct fsnotify_mark *inode_mark, | |
149 | struct fsnotify_mark *fanotify_mark, | |
150 | u32 mask, void *data, int data_type, | |
151 | const unsigned char *file_name) | |
152 | { | |
153 | int ret = 0; | |
154 | struct fanotify_event_info *event; | |
155 | struct fsnotify_event *fsn_event; | |
156 | struct fsnotify_event *notify_fsn_event; | |
157 | ||
158 | BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS); | |
159 | BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY); | |
160 | BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); | |
161 | BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE); | |
162 | BUILD_BUG_ON(FAN_OPEN != FS_OPEN); | |
163 | BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD); | |
164 | BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW); | |
165 | BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM); | |
166 | BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM); | |
167 | BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR); | |
168 | ||
83c4c4b0 JK |
169 | if (!fanotify_should_send_event(inode_mark, fanotify_mark, mask, data, |
170 | data_type)) | |
171 | return 0; | |
172 | ||
7053aee2 JK |
173 | pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode, |
174 | mask); | |
175 | ||
176 | event = kmem_cache_alloc(fanotify_event_cachep, GFP_KERNEL); | |
177 | if (unlikely(!event)) | |
178 | return -ENOMEM; | |
179 | ||
180 | fsn_event = &event->fse; | |
181 | fsnotify_init_event(fsn_event, inode, mask); | |
182 | event->tgid = get_pid(task_tgid(current)); | |
183 | if (data_type == FSNOTIFY_EVENT_PATH) { | |
184 | struct path *path = data; | |
185 | event->path = *path; | |
186 | path_get(&event->path); | |
187 | } else { | |
188 | event->path.mnt = NULL; | |
189 | event->path.dentry = NULL; | |
190 | } | |
191 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS | |
192 | event->response = 0; | |
193 | #endif | |
194 | ||
195 | notify_fsn_event = fsnotify_add_notify_event(group, fsn_event, | |
196 | fanotify_merge); | |
197 | if (notify_fsn_event) { | |
198 | /* Our event wasn't used in the end. Free it. */ | |
199 | fsnotify_destroy_event(group, fsn_event); | |
200 | if (IS_ERR(notify_fsn_event)) | |
201 | return PTR_ERR(notify_fsn_event); | |
7053aee2 JK |
202 | } |
203 | ||
204 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS | |
13116dfd | 205 | if (mask & FAN_ALL_PERM_EVENTS) |
7053aee2 JK |
206 | ret = fanotify_get_response_from_access(group, event); |
207 | #endif | |
208 | return ret; | |
209 | } | |
210 | ||
4afeff85 EP |
211 | static void fanotify_free_group_priv(struct fsnotify_group *group) |
212 | { | |
213 | struct user_struct *user; | |
214 | ||
215 | user = group->fanotify_data.user; | |
216 | atomic_dec(&user->fanotify_listeners); | |
217 | free_uid(user); | |
218 | } | |
219 | ||
7053aee2 JK |
220 | static void fanotify_free_event(struct fsnotify_event *fsn_event) |
221 | { | |
222 | struct fanotify_event_info *event; | |
223 | ||
224 | event = FANOTIFY_E(fsn_event); | |
225 | path_put(&event->path); | |
226 | put_pid(event->tgid); | |
227 | kmem_cache_free(fanotify_event_cachep, event); | |
228 | } | |
229 | ||
ff0b16a9 EP |
230 | const struct fsnotify_ops fanotify_fsnotify_ops = { |
231 | .handle_event = fanotify_handle_event, | |
4afeff85 | 232 | .free_group_priv = fanotify_free_group_priv, |
7053aee2 | 233 | .free_event = fanotify_free_event, |
ff0b16a9 | 234 | }; |