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* Copyright (C) 2012 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <binder/AppOpsManager.h>
#include <binder/IPCThreadState.h>
#include <binder/IServiceManager.h>
#include <binder/PermissionCache.h>
#include <private/android_filesystem_config.h>
#include "ServiceUtilities.h"
/* When performing permission checks we do not use permission cache for
* runtime permissions (protection level dangerous) as they may change at
* runtime. All other permissions (protection level normal and dangerous)
* can be cached as they never change. Of course all permission checked
* here are platform defined.
namespace android {
// Not valid until initialized by AudioFlinger constructor. It would have to be
// re-initialized if the process containing AudioFlinger service forks (which it doesn't).
// This is often used to validate binder interface calls within audioserver
// (e.g. AudioPolicyManager to AudioFlinger).
pid_t getpid_cached;
// A trusted calling UID may specify the client UID as part of a binder interface call.
// otherwise the calling UID must be equal to the client UID.
bool isTrustedCallingUid(uid_t uid) {
switch (uid) {
return true;
return false;
bool recordingAllowed(const String16& opPackageName, pid_t pid, uid_t uid) {
// we're always OK.
if (getpid_cached == IPCThreadState::self()->getCallingPid()) return true;
static const String16 sRecordAudio("android.permission.RECORD_AUDIO");
// We specify a pid and uid here as mediaserver (aka MediaRecorder or StageFrightRecorder)
// may open a record track on behalf of a client. Note that pid may be a tid.
// IMPORTANT: Don't use PermissionCache - a runtime permission and may change.
const bool ok = checkPermission(sRecordAudio, pid, uid);
if (!ok) {
ALOGE("Request requires android.permission.RECORD_AUDIO");
return false;
// To permit command-line native tests
if (uid == AID_ROOT) return true;
String16 checkedOpPackageName = opPackageName;
// In some cases the calling code has no access to the package it runs under.
// For example, code using the wilhelm framework's OpenSL-ES APIs. In this
// case we will get the packages for the calling UID and pick the first one
// for attributing the app op. This will work correctly for runtime permissions
// as for legacy apps we will toggle the app op for all packages in the UID.
// The caveat is that the operation may be attributed to the wrong package and
// stats based on app ops may be slightly off.
if (checkedOpPackageName.size() <= 0) {
sp<IServiceManager> sm = defaultServiceManager();
sp<IBinder> binder = sm->getService(String16("permission"));
if (binder == 0) {
ALOGE("Cannot get permission service");
return false;
sp<IPermissionController> permCtrl = interface_cast<IPermissionController>(binder);
Vector<String16> packages;
permCtrl->getPackagesForUid(uid, packages);
if (packages.isEmpty()) {
ALOGE("No packages for calling UID");
return false;
checkedOpPackageName = packages[0];
AppOpsManager appOps;
if (appOps.noteOp(AppOpsManager::OP_RECORD_AUDIO, uid, checkedOpPackageName)
!= AppOpsManager::MODE_ALLOWED) {
ALOGE("Request denied by app op OP_RECORD_AUDIO");
return false;
return true;
bool captureAudioOutputAllowed(pid_t pid, uid_t uid) {
if (getpid_cached == IPCThreadState::self()->getCallingPid()) return true;
static const String16 sCaptureAudioOutput("android.permission.CAPTURE_AUDIO_OUTPUT");
bool ok = checkPermission(sCaptureAudioOutput, pid, uid);
if (!ok) ALOGE("Request requires android.permission.CAPTURE_AUDIO_OUTPUT");
return ok;
bool captureHotwordAllowed(pid_t pid, uid_t uid) {
// CAPTURE_AUDIO_HOTWORD permission implies RECORD_AUDIO permission
bool ok = recordingAllowed(String16(""), pid, uid);
if (ok) {
static const String16 sCaptureHotwordAllowed("android.permission.CAPTURE_AUDIO_HOTWORD");
// IMPORTANT: Use PermissionCache - not a runtime permission and may not change.
ok = PermissionCache::checkCallingPermission(sCaptureHotwordAllowed);
if (!ok) ALOGE("android.permission.CAPTURE_AUDIO_HOTWORD");
return ok;
bool settingsAllowed() {
if (getpid_cached == IPCThreadState::self()->getCallingPid()) return true;
static const String16 sAudioSettings("android.permission.MODIFY_AUDIO_SETTINGS");
// IMPORTANT: Use PermissionCache - not a runtime permission and may not change.
bool ok = PermissionCache::checkCallingPermission(sAudioSettings);
if (!ok) ALOGE("Request requires android.permission.MODIFY_AUDIO_SETTINGS");
return ok;
bool modifyAudioRoutingAllowed() {
static const String16 sModifyAudioRoutingAllowed("android.permission.MODIFY_AUDIO_ROUTING");
// IMPORTANT: Use PermissionCache - not a runtime permission and may not change.
bool ok = PermissionCache::checkCallingPermission(sModifyAudioRoutingAllowed);
if (!ok) ALOGE("android.permission.MODIFY_AUDIO_ROUTING");
return ok;
bool dumpAllowed() {
// don't optimize for same pid, since mediaserver never dumps itself
static const String16 sDump("android.permission.DUMP");
// IMPORTANT: Use PermissionCache - not a runtime permission and may not change.
bool ok = PermissionCache::checkCallingPermission(sDump);
// convention is for caller to dump an error message to fd instead of logging here
//if (!ok) ALOGE("Request requires android.permission.DUMP");
return ok;
} // namespace android