Merge changes Ib19a0cbd,I01b2312c into main

* changes:
  binder_parcel_fuzzer: support owned Parcels
  libbinder: remove overeager fdsan crash

Author: Steven Moreland

libs/binder/Parcel.cpp

@@ -156,7 +156,7 @@ enum {
 
 #ifdef BINDER_WITH_KERNEL_IPC
 static void acquire_object(const sp<ProcessState>& proc, const flat_binder_object& obj,
-                           const void* who) {
+                           const void* who, bool tagFds) {
     switch (obj.hdr.type) {
         case BINDER_TYPE_BINDER:
             if (obj.binder) {
@@ -173,7 +173,7 @@ static void acquire_object(const sp<ProcessState>& proc, const flat_binder_objec
             return;
         }
         case BINDER_TYPE_FD: {
-            if (obj.cookie != 0) { // owned
+            if (tagFds && obj.cookie != 0) { // owned
                 FdTag(obj.handle, nullptr, who);
             }
             return;
@@ -611,7 +611,7 @@ status_t Parcel::appendFrom(const Parcel* parcel, size_t offset, size_t len) {
                     }
                 }
 
-                acquire_object(proc, *flat, this);
+                acquire_object(proc, *flat, this, true /*tagFds*/);
             }
         }
 #else
@@ -1797,7 +1797,7 @@ status_t Parcel::writeObject(const flat_binder_object& val, bool nullMetaData)
         // Need to write meta-data?
         if (nullMetaData || val.binder != 0) {
             kernelFields->mObjects[kernelFields->mObjectsSize] = mDataPos;
-            acquire_object(ProcessState::self(), val, this);
+            acquire_object(ProcessState::self(), val, this, true /*tagFds*/);
             kernelFields->mObjectsSize++;
         }
 
@@ -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;
@@ -2883,15 +2944,17 @@ void Parcel::releaseObjects()
 #endif // BINDER_WITH_KERNEL_IPC
 }
 
-void Parcel::acquireObjects()
-{
+void Parcel::reacquireObjects(size_t objectsSize) {
     auto* kernelFields = maybeKernelFields();
     if (kernelFields == nullptr) {
         return;
     }
 
 #ifdef BINDER_WITH_KERNEL_IPC
-    size_t i = kernelFields->mObjectsSize;
+    LOG_ALWAYS_FATAL_IF(objectsSize > kernelFields->mObjectsSize,
+                        "Object size %zu out of range of %zu", objectsSize,
+                        kernelFields->mObjectsSize);
+    size_t i = objectsSize;
     if (i == 0) {
         return;
     }
@@ -2901,8 +2964,10 @@ void Parcel::acquireObjects()
     while (i > 0) {
         i--;
         const flat_binder_object* flat = reinterpret_cast<flat_binder_object*>(data + objects[i]);
-        acquire_object(proc, *flat, this);
+        acquire_object(proc, *flat, this, false /*tagFds*/); // they are already tagged
     }
+#else
+    (void) objectsSize;
 #endif // BINDER_WITH_KERNEL_IPC
 }
 
@@ -3119,12 +3184,8 @@ status_t Parcel::continueWrite(size_t desired)
                 return NO_MEMORY;
             }
 
-            // Little hack to only acquire references on objects
-            // we will be keeping.
-            size_t oldObjectsSize = kernelFields->mObjectsSize;
-            kernelFields->mObjectsSize = objectsSize;
-            acquireObjects();
-            kernelFields->mObjectsSize = oldObjectsSize;
+            // only acquire references on objects we are keeping
+            reacquireObjects(objectsSize);
         }
         if (rpcFields) {
             if (status_t status = truncateRpcObjects(objectsSize); status != OK) {

libs/binder/include/binder/Parcel.h

@@ -649,6 +649,11 @@ class Parcel {
 
     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);
@@ -664,15 +669,15 @@ class Parcel {
     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,
             release_func relFunc);
 
     status_t            finishWrite(size_t len);
     void                releaseObjects();
-    void                acquireObjects();
+    void reacquireObjects(size_t objectSize);
     status_t            growData(size_t len);
     // Clear the Parcel and set the capacity to `desired`.
     // Doesn't reset the RPC session association.

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

@@ -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

@@ -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

@@ -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

libs/binder/tests/parcel_fuzzer/random_parcel_seeds.cpp

@@ -281,9 +281,9 @@ void generateSeedsFromRecording(borrowed_fd fd,
     // This buffer holds the bytes which will be used for fillRandomParcel API
     std::vector<uint8_t> fillParcelBuffer;
 
-    // Don't take rpc path
-    uint8_t rpcBranch = 0;
-    impl::writeReversedBuffer(fillParcelBuffer, rpcBranch);
+    // Use all default options.
+    uint8_t parcelOptions = 0;
+    impl::writeReversedBuffer(fillParcelBuffer, parcelOptions);
 
     // Implicit branch on this path -> options->writeHeader(p, provider)
     uint8_t writeHeaderInternal = 0;