PermissionCache.h revision 99b49840d309727678b77403d6cc9f920111623f 
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
26namespace android {
27// ---------------------------------------------------------------------------
28
29/*
30 * PermissionCache caches permission checks for a given uid.
31 *
32 * Currently the cache is not updated when there is a permission change,
33 * for instance when an application is uninstalled.
34 *
35 * IMPORTANT: for the reason stated above, only system permissions are safe
36 * to cache. This restriction may be lifted at a later time.
37 *
38 */
39
40class PermissionCache : Singleton<PermissionCache> {
41    struct Entry {
42        String16    name;
43        uid_t       uid;
44        bool        granted;
45        inline bool operator < (const Entry& e) const {
46            return (uid == e.uid) ? (name < e.name) : (uid < e.uid);
47        }
48    };
49    mutable Mutex mLock;
50    // we pool all the permission names we see, as many permissions checks
51    // will have identical names
52    SortedVector< String16 > mPermissionNamesPool;
53    // this is our cache per say. it stores pooled names.
54    SortedVector< Entry > mCache;
55
56    // free the whole cache, but keep the permission name pool
57    void purge();
58
59    status_t check(bool* granted,
60            const String16& permission, uid_t uid) const;
61
62    void cache(const String16& permission, uid_t uid, bool granted);
63
64public:
65    PermissionCache();
66
67    static bool checkCallingPermission(const String16& permission);
68
69    static bool checkCallingPermission(const String16& permission,
70                                int32_t* outPid, int32_t* outUid);
71
72    static bool checkPermission(const String16& permission,
73            pid_t pid, uid_t uid);
74};
75
76// ---------------------------------------------------------------------------
77}; // namespace android
78
79#endif /* BINDER_PERMISSION_H */
80