1 /*
2  * Copyright (C) 2009 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef BINDER_PERMISSION_H
18 #define BINDER_PERMISSION_H
19 
20 #include <stdint.h>
21 #include <unistd.h>
22 
23 #include <utils/String16.h>
24 #include <utils/Singleton.h>
25 #include <utils/SortedVector.h>
26 
27 namespace android {
28 // ---------------------------------------------------------------------------
29 
30 /*
31  * PermissionCache caches permission checks for a given uid.
32  *
33  * Currently the cache is not updated when there is a permission change,
34  * for instance when an application is uninstalled.
35  *
36  * IMPORTANT: for the reason stated above, only system permissions are safe
37  * to cache. This restriction may be lifted at a later time.
38  *
39  */
40 
41 class PermissionCache : Singleton<PermissionCache> {
42     struct Entry {
43         String16    name;
44         uid_t       uid;
45         bool        granted;
46         inline bool operator < (const Entry& e) const {
47             return (uid == e.uid) ? (name < e.name) : (uid < e.uid);
48         }
49     };
50     mutable Mutex mLock;
51     // we pool all the permission names we see, as many permissions checks
52     // will have identical names
53     SortedVector< String16 > mPermissionNamesPool;
54     // this is our cache per say. it stores pooled names.
55     SortedVector< Entry > mCache;
56 
57     // free the whole cache, but keep the permission name pool
58     void purge();
59 
60     status_t check(bool* granted,
61             const String16& permission, uid_t uid) const;
62 
63     void cache(const String16& permission, uid_t uid, bool granted);
64 
65 public:
66     PermissionCache();
67 
68     static bool checkCallingPermission(const String16& permission);
69 
70     static bool checkCallingPermission(const String16& permission,
71                                 int32_t* outPid, int32_t* outUid);
72 
73     static bool checkPermission(const String16& permission,
74             pid_t pid, uid_t uid);
75 };
76 
77 // ---------------------------------------------------------------------------
78 }; // namespace android
79 
80 #endif /* BINDER_PERMISSION_H */
81