1 /* 2 * Copyright (C) 2015 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 package android.support.v4.content; 18 19 import android.content.Context; 20 import android.content.pm.PackageManager; 21 import android.os.Binder; 22 import android.os.Process; 23 import android.support.annotation.IntDef; 24 import android.support.annotation.NonNull; 25 import android.support.v4.app.AppOpsManagerCompat; 26 27 import java.lang.annotation.Retention; 28 import java.lang.annotation.RetentionPolicy; 29 30 /** 31 * This class provides permission check APIs that verify both the 32 * permission and the associated app op for this permission if 33 * such is defined. 34 * <p> 35 * In the new permission model permissions with protection level 36 * dangerous are runtime permissions. For apps targeting {@link android.os.Build.VERSION_CODES#M} 37 * and above the user may not grant such permissions or revoke 38 * them at any time. For apps targeting API lower than {@link android.os.Build.VERSION_CODES#M} 39 * these permissions are always granted as such apps do not expect 40 * permission revocations and would crash. Therefore, when the 41 * user disables a permission for a legacy app in the UI the 42 * platform disables the APIs guarded by this permission making 43 * them a no-op which is doing nothing or returning an empty 44 * result or default error. 45 * </p> 46 * <p> 47 * It is important that when you perform an operation on behalf of 48 * another app you use these APIs to check for permissions as the 49 * app may be a legacy app that does not participate in the new 50 * permission model for which the user had disabled the "permission" 51 * which is achieved by disallowing the corresponding app op. 52 * </p> 53 */ 54 public final class PermissionChecker { 55 /** Permission result: The permission is granted. */ 56 public static final int PERMISSION_GRANTED = PackageManager.PERMISSION_GRANTED; 57 58 /** Permission result: The permission is denied. */ 59 public static final int PERMISSION_DENIED = PackageManager.PERMISSION_DENIED; 60 61 /** Permission result: The permission is denied because the app op is not allowed. */ 62 public static final int PERMISSION_DENIED_APP_OP = PackageManager.PERMISSION_DENIED - 1; 63 64 @IntDef({PERMISSION_GRANTED, 65 PERMISSION_DENIED, 66 PERMISSION_DENIED_APP_OP}) 67 @Retention(RetentionPolicy.SOURCE) 68 public @interface PermissionResult {} 69 PermissionChecker()70 private PermissionChecker() { 71 /* do nothing */ 72 } 73 74 /** 75 * Checks whether a given package in a UID and PID has a given permission 76 * and whether the app op that corresponds to this permission is allowed. 77 * 78 * @param context Context for accessing resources. 79 * @param permission The permission to check. 80 * @param pid The process id for which to check. 81 * @param uid The uid for which to check. 82 * @param packageName The package name for which to check. If null the 83 * the first package for the calling UID will be used. 84 * @return The permission check result which is either {@link #PERMISSION_GRANTED} 85 * or {@link #PERMISSION_DENIED} or {@link #PERMISSION_DENIED_APP_OP}. 86 */ checkPermission(@onNull Context context, @NonNull String permission, int pid, int uid, String packageName)87 public static int checkPermission(@NonNull Context context, @NonNull String permission, 88 int pid, int uid, String packageName) { 89 if (context.checkPermission(permission, pid, uid) == PackageManager.PERMISSION_DENIED) { 90 return PERMISSION_DENIED; 91 } 92 93 String op = AppOpsManagerCompat.permissionToOp(permission); 94 if (op == null) { 95 return PERMISSION_GRANTED; 96 } 97 98 if (packageName == null) { 99 String[] packageNames = context.getPackageManager().getPackagesForUid(uid); 100 if (packageNames == null || packageNames.length <= 0) { 101 return PERMISSION_DENIED; 102 } 103 packageName = packageNames[0]; 104 } 105 106 if (AppOpsManagerCompat.noteProxyOp(context, op, packageName) 107 != AppOpsManagerCompat.MODE_ALLOWED) { 108 return PERMISSION_DENIED_APP_OP; 109 } 110 111 return PERMISSION_GRANTED; 112 } 113 114 /** 115 * Checks whether your app has a given permission and whether the app op 116 * that corresponds to this permission is allowed. 117 * 118 * @param context Context for accessing resources. 119 * @param permission The permission to check. 120 * @return The permission check result which is either {@link #PERMISSION_GRANTED} 121 * or {@link #PERMISSION_DENIED} or {@link #PERMISSION_DENIED_APP_OP}. 122 */ checkSelfPermission(@onNull Context context, @NonNull String permission)123 public static int checkSelfPermission(@NonNull Context context, 124 @NonNull String permission) { 125 return checkPermission(context, permission, android.os.Process.myPid(), 126 android.os.Process.myUid(), context.getPackageName()); 127 } 128 129 /** 130 * Checks whether the IPC you are handling has a given permission and whether 131 * the app op that corresponds to this permission is allowed. 132 * 133 * @param context Context for accessing resources. 134 * @param permission The permission to check. 135 * @param packageName The package name making the IPC. If null the 136 * the first package for the calling UID will be used. 137 * @return The permission check result which is either {@link #PERMISSION_GRANTED} 138 * or {@link #PERMISSION_DENIED} or {@link #PERMISSION_DENIED_APP_OP}. 139 */ checkCallingPermission(@onNull Context context, @NonNull String permission, String packageName)140 public static int checkCallingPermission(@NonNull Context context, 141 @NonNull String permission, String packageName) { 142 if (Binder.getCallingPid() == Process.myPid()) { 143 return PackageManager.PERMISSION_DENIED; 144 } 145 return checkPermission(context, permission, Binder.getCallingPid(), 146 Binder.getCallingUid(), packageName); 147 } 148 149 /** 150 * Checks whether the IPC you are handling or your app has a given permission 151 * and whether the app op that corresponds to this permission is allowed. 152 * 153 * @param context Context for accessing resources. 154 * @param permission The permission to check. 155 * @return The permission check result which is either {@link #PERMISSION_GRANTED} 156 * or {@link #PERMISSION_DENIED} or {@link #PERMISSION_DENIED_APP_OP}. 157 */ checkCallingOrSelfPermission(@onNull Context context, @NonNull String permission)158 public static int checkCallingOrSelfPermission(@NonNull Context context, 159 @NonNull String permission) { 160 String packageName = (Binder.getCallingPid() == Process.myPid()) 161 ? context.getPackageName() : null; 162 return checkPermission(context, permission, Binder.getCallingPid(), 163 Binder.getCallingUid(), packageName); 164 } 165 } 166