| /* |
| * Copyright (C) 2019 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 |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include <android-base/logging.h> |
| #include <android/ashmemd/IAshmemDeviceService.h> |
| #include <binder/IServiceManager.h> |
| #include <cutils/android_filesystem_config.h> |
| |
| using android::IBinder; |
| using android::IServiceManager; |
| using android::String16; |
| using android::ashmemd::IAshmemDeviceService; |
| using android::os::ParcelFileDescriptor; |
| |
| namespace android { |
| namespace ashmemd { |
| |
| static bool checkBinderAccess() { |
| // Isolated apps are potentially subject to seccomp policy that restricts use of access() |
| // (b/129483782). However, apps always have access to binder, so return true. |
| auto uid = getuid() % AID_USER; |
| if (AID_ISOLATED_START <= uid && uid <= AID_ISOLATED_END) { |
| return true; |
| } |
| if (access("/dev/binder", R_OK | W_OK) == 0) { |
| return true; |
| } |
| return false; |
| } |
| |
| sp<IAshmemDeviceService> getAshmemService() { |
| // Calls to defaultServiceManager() crash the process if it doesn't have appropriate |
| // binder permissions. Check these permissions proactively. |
| if (!checkBinderAccess()) { |
| return nullptr; |
| } |
| sp<IServiceManager> sm = android::defaultServiceManager(); |
| sp<IBinder> binder = sm->checkService(String16("ashmem_device_service")); |
| return interface_cast<IAshmemDeviceService>(binder); |
| } |
| |
| extern "C" int openAshmemdFd() { |
| static sp<IAshmemDeviceService> ashmemService = getAshmemService(); |
| if (!ashmemService) { |
| LOG(ERROR) << "Failed to get IAshmemDeviceService."; |
| return -1; |
| } |
| |
| ParcelFileDescriptor fd; |
| auto status = ashmemService->open(&fd); |
| if (!status.isOk()) { |
| LOG(ERROR) << "Failed IAshmemDeviceService::open()"; |
| return -1; |
| } |
| |
| // unique_fd is the underlying type of ParcelFileDescriptor, i.e. fd is |
| // closed when it falls out of scope, so we make a dup. |
| return dup(fd.get()); |
| } |
| |
| } // namespace ashmemd |
| } // namespace android |