hwbinder: explicitly disallow local java binder

Local binders from Java are currently not supported. However, changes
which make them appear to work are planned (but which will also make
using them require unnecessary parceling). Explicitly disabling them
so that there is a clear error message instead of random errors.

Bug: 129150021
Test: boot, check logs
Test: system/tools/hidl/test/run_all_device_tests.sh
Change-Id: I107cbc768d6285b50c0eef6d41a16155d76e35dd

core/jni/android_os_HwBinder.cpp

@@ -224,6 +224,21 @@ status_t JHwBinder::onTransact(
     return err;
 }
 
+bool validateCanUseHwBinder(const sp<hardware::IBinder>& binder) {
+    if (binder != nullptr && binder->localBinder() != nullptr) {
+        // untested/unsupported/inefficient
+        // see b/129150021, doesn't work with scatter-gather
+        //
+        // explicitly disabling until it is supported
+        // (note, even if this is fixed to work with scatter gather, we would also need
+        // to convert this to the Java object rather than re-wrapping with a proxy)
+        LOG(ERROR) << "Local Java Binder not supported.";
+        return false;
+    }
+
+    return true;
+}
+
 }  // namespace android
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -324,9 +339,9 @@ static jobject JHwBinder_native_getService(
     sp<IBase> ret = getRawServiceInternal(ifaceName, serviceName, retry /* retry */, false /* getStub */);
     sp<hardware::IBinder> service = hardware::toBinder<hidl::base::V1_0::IBase>(ret);
 
-    if (service == NULL) {
+    if (service == nullptr || !validateCanUseHwBinder(service)) {
         signalExceptionForError(env, NAME_NOT_FOUND);
-        return NULL;
+        return nullptr;
     }
 
     LOG(INFO) << "HwBinder: Starting thread pool for getting: " << ifaceName << "/" << serviceName;

core/jni/android_os_HwBinder.h

@@ -54,6 +54,8 @@ private:
 
 int register_android_os_HwBinder(JNIEnv *env);
 
+bool validateCanUseHwBinder(const sp<hardware::IBinder>& binder);
+
 }  // namespace android
 
 #endif  // _ANDROID_OS_HW_BINDER_H

core/jni/android_os_HwParcel.cpp

@@ -883,8 +883,12 @@ static jobject JHwParcel_native_readStrongBinder(JNIEnv *env, jobject thiz) {
 
     sp<hardware::IBinder> binder = parcel->readStrongBinder();
 
-    if (binder == NULL) {
-        return NULL;
+    if (binder == nullptr) {
+        return nullptr;
+    }
+
+    if (!validateCanUseHwBinder(binder)) {
+        return nullptr;
     }
 
     return JHwRemoteBinder::NewObject(env, binder);