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/*
* Copyright (C) 2022 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 <fuzzbinder/random_binder.h>
#include <fuzzbinder/random_parcel.h>
#include <android-base/logging.h>
#include <binder/IInterface.h>
#include <binder/IServiceManager.h>
namespace android {
class RandomBinder : public BBinder {
public:
RandomBinder(const String16& descriptor, std::vector<uint8_t>&& bytes)
: mDescriptor(descriptor),
mBytes(std::move(bytes)),
mProvider(mBytes.data(), mBytes.size()) {}
const String16& getInterfaceDescriptor() const override { return mDescriptor; }
status_t onTransact(uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags) override {
(void)code;
(void)data;
(void)reply;
(void)flags; // note - for maximum coverage even ignore if oneway
if (mProvider.ConsumeBool()) {
return mProvider.ConsumeIntegral<status_t>();
}
if (reply == nullptr) return OK;
// TODO: things we could do to increase state space
// - also pull FDs and binders from 'data'
// (optionally combine these into random parcel 'options')
// - also pull FDs and binders from random parcel 'options'
RandomParcelOptions options;
// random output
std::vector<uint8_t> subData = mProvider.ConsumeBytes<uint8_t>(
mProvider.ConsumeIntegralInRange<size_t>(0, mProvider.remaining_bytes()));
fillRandomParcel(reply, FuzzedDataProvider(subData.data(), subData.size()), &options);
return OK;
}
private:
String16 mDescriptor;
// note may not all be used
std::vector<uint8_t> mBytes;
FuzzedDataProvider mProvider;
};
sp<IBinder> getRandomBinder(FuzzedDataProvider* provider) {
auto makeFunc = provider->PickValueInArray<const std::function<sp<IBinder>()>>({
[&]() {
// descriptor is the length of a class name, e.g.
// "some.package.Foo"
std::string str = provider->ConsumeRandomLengthString(100 /*max length*/);
// arbitrarily consume remaining data to create a binder that can return
// random results - coverage guided fuzzer should ensure all of the remaining
// data isn't always used
std::vector<uint8_t> bytes = provider->ConsumeBytes<uint8_t>(
provider->ConsumeIntegralInRange<size_t>(0, provider->remaining_bytes()));
return new RandomBinder(String16(str.c_str()), std::move(bytes));
},
[]() {
// this is the easiest remote binder to get ahold of, and it
// should be able to handle anything thrown at it, and
// essentially every process can talk to it, so it's a good
// candidate for checking usage of an actual BpBinder
return IInterface::asBinder(defaultServiceManager());
},
[&]() -> sp<IBinder> { return nullptr; },
});
return makeFunc();
}
} // namespace android
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