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Commit b09a1d23 authored by Steven Moreland's avatar Steven Moreland
Browse files

binder_parcel_fuzzer: support owned Parcels 

Some codepaths in Parcel are different when the Parcel
is owned. This allows fillRandomParcel to also sometimes
cause the returned Parcel be a view of a filled out
Parcel. This increases the possible impact and bug
finding abilities of all of our AIDL fuzzers as well.

Ignore-AOSP-First: fuzzing
Bug: 369404061
Test: binder_parcel_fuzzer
Change-Id: Ib19a0cbd74d48e18ba36cff56202541105ef9163
parent 750d69b2

libs/binder/Parcel.cpp

+61 −0
Original line number Diff line number Diff line
@@ -2728,6 +2728,65 @@ size_t Parcel::ipcObjectsCount() const 
    return 0;

}



static void do_nothing_release_func(const uint8_t* data, size_t dataSize,

                                    const binder_size_t* objects, size_t objectsCount) {

    (void)data;

    (void)dataSize;

    (void)objects;

    (void)objectsCount;

}

static void delete_data_release_func(const uint8_t* data, size_t dataSize,

                                     const binder_size_t* objects, size_t objectsCount) {

    delete[] data;

    (void)dataSize;

    (void)objects;

    (void)objectsCount;

}



void Parcel::makeDangerousViewOf(Parcel* p) {

    if (p->isForRpc()) {

        // warning: this must match the logic in rpcSetDataReference

        auto* rf = p->maybeRpcFields();

        LOG_ALWAYS_FATAL_IF(rf == nullptr);

        std::vector<std::variant<binder::unique_fd, binder::borrowed_fd>> fds;

        if (rf->mFds) {

            fds.reserve(rf->mFds->size());

            for (const auto& fd : *rf->mFds) {

                fds.push_back(binder::borrowed_fd(toRawFd(fd)));

            }

        }

        status_t result =

                rpcSetDataReference(rf->mSession, p->mData, p->mDataSize,

                                    rf->mObjectPositions.data(), rf->mObjectPositions.size(),

                                    std::move(fds), do_nothing_release_func);

        LOG_ALWAYS_FATAL_IF(result != OK, "Failed: %s", statusToString(result).c_str());

    } else {

#ifdef BINDER_WITH_KERNEL_IPC

        // warning: this must match the logic in ipcSetDataReference

        auto* kf = p->maybeKernelFields();

        LOG_ALWAYS_FATAL_IF(kf == nullptr);



        // Ownership of FDs is passed to the Parcel from kernel binder. This should be refactored

        // to move this ownership out of Parcel and into release_func. However, today, Parcel

        // always assums it can own and close FDs today. So, for purposes of testing consistency,

        // , create new FDs it can own.



        uint8_t* newData = new uint8_t[p->mDataSize]; // deleted by delete_data_release_func

        memcpy(newData, p->mData, p->mDataSize);

        for (size_t i = 0; i < kf->mObjectsSize; i++) {

            flat_binder_object* flat =

                    reinterpret_cast<flat_binder_object*>(newData + kf->mObjects[i]);

            if (flat->hdr.type == BINDER_TYPE_FD) {

                flat->handle = fcntl(flat->handle, F_DUPFD_CLOEXEC, 0);

            }

        }



        ipcSetDataReference(newData, p->mDataSize, kf->mObjects, kf->mObjectsSize,

                            delete_data_release_func);

#endif // BINDER_WITH_KERNEL_IPC

    }

}



void Parcel::ipcSetDataReference(const uint8_t* data, size_t dataSize, const binder_size_t* objects,

                                 size_t objectsCount, release_func relFunc) {

    // this code uses 'mOwner == nullptr' to understand whether it owns memory
@@ -2738,6 +2797,7 @@ void Parcel::ipcSetDataReference(const uint8_t* data, size_t dataSize, const bin 
    auto* kernelFields = maybeKernelFields();

    LOG_ALWAYS_FATAL_IF(kernelFields == nullptr); // guaranteed by freeData.



    // must match makeDangerousViewOf

    mData = const_cast<uint8_t*>(data);

    mDataSize = mDataCapacity = dataSize;

    kernelFields->mObjects = const_cast<binder_size_t*>(objects);
@@ -2816,6 +2876,7 @@ status_t Parcel::rpcSetDataReference( 
    auto* rpcFields = maybeRpcFields();

    LOG_ALWAYS_FATAL_IF(rpcFields == nullptr); // guaranteed by markForRpc.



    // must match makeDangerousViewOf

    mData = const_cast<uint8_t*>(data);

    mDataSize = mDataCapacity = dataSize;

    mOwner = relFunc;

libs/binder/include/binder/Parcel.h

+6 −1
Original line number Diff line number Diff line
@@ -649,6 +649,11 @@ public: 


    LIBBINDER_EXPORTED void print(std::ostream& to, uint32_t flags = 0) const;



    // This API is to quickly become a view of another Parcel, so that we can also

    // test 'owner' paths quickly. It's extremely dangerous to use this API in

    // practice, and you should never ever do it.

    LIBBINDER_EXPORTED void makeDangerousViewOf(Parcel* p);



private:

    // Close all file descriptors in the parcel at object positions >= newObjectsSize.

    void closeFileDescriptors(size_t newObjectsSize);
@@ -664,7 +669,7 @@ private: 
    void ipcSetDataReference(const uint8_t* data, size_t dataSize, const binder_size_t* objects,

                             size_t objectsCount, release_func relFunc);

    // Takes ownership even when an error is returned.

    status_t rpcSetDataReference(

    [[nodiscard]] status_t rpcSetDataReference(

            const sp<RpcSession>& session, const uint8_t* data, size_t dataSize,

            const uint32_t* objectTable, size_t objectTableSize,

            std::vector<std::variant<binder::unique_fd, binder::borrowed_fd>>&& ancillaryFds,

libs/binder/tests/parcel_fuzzer/include_random_parcel/fuzzbinder/random_parcel.h

+3 −0
Original line number Diff line number Diff line
@@ -28,6 +28,9 @@ struct RandomParcelOptions { 
    std::function<void(Parcel* p, FuzzedDataProvider& provider)> writeHeader;

    std::vector<sp<IBinder>> extraBinders;

    std::vector<binder::unique_fd> extraFds;



    // internal state owned by fillRandomParcel, for Parcel views

    std::vector<std::unique_ptr<Parcel>> extraParcels;

};



/**

libs/binder/tests/parcel_fuzzer/main.cpp

+8 −3
Original line number Diff line number Diff line
@@ -70,7 +70,7 @@ void doTransactFuzz(const char* backend, const sp<B>& binder, FuzzedDataProvider 
    uint32_t code = provider.ConsumeIntegral<uint32_t>();

    uint32_t flag = provider.ConsumeIntegral<uint32_t>();



    FUZZ_LOG() << "backend: " << backend;

    FUZZ_LOG() << "doTransactFuzz backend: " << backend;



    RandomParcelOptions options;
@@ -101,7 +101,7 @@ void doReadFuzz(const char* backend, const std::vector<ParcelRead<P>>& reads, 
    // since we are only using a byte to index

    CHECK_LE(reads.size(), 255u) << reads.size();



    FUZZ_LOG() << "backend: " << backend;

    FUZZ_LOG() << "doReadFuzz backend: " << backend;

    FUZZ_LOG() << "input: " << HexString(p.data(), p.dataSize());

    FUZZ_LOG() << "instructions: " << HexString(instructions.data(), instructions.size());
@@ -122,10 +122,15 @@ void doReadWriteFuzz(const char* backend, const std::vector<ParcelRead<P>>& read 
    RandomParcelOptions options;

    P p;



    // small amount of initial Parcel data, since fillRandomParcel uses makeDangerousViewOf

    std::vector<uint8_t> parcelData =

            provider.ConsumeBytes<uint8_t>(provider.ConsumeIntegralInRange<size_t>(0, 20));

    fillRandomParcel(&p, FuzzedDataProvider(parcelData.data(), parcelData.size()), &options);



    // since we are only using a byte to index

    CHECK_LE(reads.size() + writes.size(), 255u) << reads.size();



    FUZZ_LOG() << "backend: " << backend;

    FUZZ_LOG() << "doReadWriteFuzz backend: " << backend;



    while (provider.remaining_bytes() > 0) {

        uint8_t idx = provider.ConsumeIntegralInRange<uint8_t>(0, reads.size() + writes.size() - 1);

libs/binder/tests/parcel_fuzzer/random_parcel.cpp

+22 −2
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <fuzzbinder/random_parcel.h>



#include <android-base/logging.h>

#include <binder/Functional.h>

#include <binder/RpcSession.h>

#include <binder/RpcTransportRaw.h>

#include <fuzzbinder/random_binder.h>
@@ -32,10 +33,29 @@ static void fillRandomParcelData(Parcel* p, FuzzedDataProvider&& provider) { 
    CHECK(OK == p->write(data.data(), data.size()));

}



void fillRandomParcel(Parcel* p, FuzzedDataProvider&& provider, RandomParcelOptions* options) {

void fillRandomParcel(Parcel* outputParcel, FuzzedDataProvider&& provider,

                      RandomParcelOptions* options) {

    CHECK_NE(options, nullptr);



    if (provider.ConsumeBool()) {

    const uint8_t fuzzerParcelOptions = provider.ConsumeIntegral<uint8_t>();

    const bool resultShouldBeView = fuzzerParcelOptions & 1;

    const bool resultShouldBeRpc = fuzzerParcelOptions & 2;



    Parcel* p;

    if (resultShouldBeView) {

        options->extraParcels.push_back(std::make_unique<Parcel>());

        // held for duration of test, so that view will be valid

        p = options->extraParcels[options->extraParcels.size() - 1].get();

    } else {

        p = outputParcel; // directly fill out the output Parcel

    }

    auto viewify_guard = binder::impl::make_scope_guard([&]() {

        if (resultShouldBeView) {

            outputParcel->makeDangerousViewOf(p);

        }

    });



    if (resultShouldBeRpc) {

        auto session = RpcSession::make(RpcTransportCtxFactoryRaw::make());

        CHECK_EQ(OK, session->addNullDebuggingClient());

        // Set the protocol version so that we don't crash if the session