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