1 /* 2 * Copyright (C) 2012 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 com.android.server.os; 18 19 import android.content.pm.PackageManager; 20 import android.os.Binder; 21 import android.os.ISchedulingPolicyService; 22 import android.os.Process; 23 import android.util.Log; 24 25 /** 26 * The implementation of the scheduling policy service interface. 27 * 28 * @hide 29 */ 30 public class SchedulingPolicyService extends ISchedulingPolicyService.Stub { 31 32 private static final String TAG = "SchedulingPolicyService"; 33 34 // Minimum and maximum values allowed for requestPriority parameter prio 35 private static final int PRIORITY_MIN = 1; 36 private static final int PRIORITY_MAX = 3; 37 SchedulingPolicyService()38 public SchedulingPolicyService() { 39 } 40 41 // TODO(b/35196900) We should pass the period in time units, rather 42 // than a fixed priority number. requestPriority(int pid, int tid, int prio, boolean isForApp)43 public int requestPriority(int pid, int tid, int prio, boolean isForApp) { 44 //Log.i(TAG, "requestPriority(pid=" + pid + ", tid=" + tid + ", prio=" + prio + ")"); 45 46 // Verify that the caller uid is permitted, priority is in range, 47 // and that the callback thread specified by app belongs to the app that 48 // called mediaserver or audioserver. 49 // Once we've verified that the caller uid is permitted, we can trust the pid but 50 // we can't trust the tid. No need to explicitly check for pid == 0 || tid == 0, 51 // since if not the case then the getThreadGroupLeader() test will also fail. 52 if (!isPermitted() || prio < PRIORITY_MIN || 53 prio > PRIORITY_MAX || Process.getThreadGroupLeader(tid) != pid) { 54 return PackageManager.PERMISSION_DENIED; 55 } 56 if (Binder.getCallingUid() != Process.BLUETOOTH_UID) { 57 try { 58 // make good use of our CAP_SYS_NICE capability 59 Process.setThreadGroup(tid, !isForApp ? 60 Process.THREAD_GROUP_AUDIO_SYS : Process.THREAD_GROUP_RT_APP); 61 } catch (RuntimeException e) { 62 Log.e(TAG, "Failed setThreadGroup: " + e); 63 return PackageManager.PERMISSION_DENIED; 64 } 65 } 66 try { 67 // must be in this order or it fails the schedulability constraint 68 Process.setThreadScheduler(tid, Process.SCHED_FIFO | Process.SCHED_RESET_ON_FORK, 69 prio); 70 } catch (RuntimeException e) { 71 Log.e(TAG, "Failed setThreadScheduler: " + e); 72 return PackageManager.PERMISSION_DENIED; 73 } 74 return PackageManager.PERMISSION_GRANTED; 75 } 76 isPermitted()77 private boolean isPermitted() { 78 // schedulerservice hidl 79 if (Binder.getCallingPid() == Process.myPid()) { 80 return true; 81 } 82 83 switch (Binder.getCallingUid()) { 84 case Process.AUDIOSERVER_UID: // fastcapture, fastmixer 85 case Process.CAMERASERVER_UID: // camera high frame rate recording 86 case Process.BLUETOOTH_UID: // Bluetooth audio playback 87 return true; 88 default: 89 return false; 90 } 91 } 92 } 93