PermissionCache.h revision db403e8ff0d7727015e1a5009bab20eb7ec205bc 
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
27namespace 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
41class 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
65public:
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