commit fbe12547099123e6b7fd867750df26ee0ca6e2d1
author Steven Moreland <smoreland@google.com> Tue Oct 27 17:31:25 2020 +0000
committer Steven Moreland <smoreland@google.com> Thu Oct 29 18:10:55 2020 +0000
tree 4f3aebe014762e315e96d6a6e4c75da61391faab
parent dcaacee8afb0fea9a92bc4196e0f22aa66f99ecc

IBinder: support FLAG_CLEAR_BUF

This is @hide and it isn't expected to be very useful in Java, since,
for instance, we would need a corresponding way to clear the data
associated with a Java String object. However, it's here for symmetry.

Bug: 171501998
Test: aidl_integration_test
Change-Id: I9d81f6138c74561b934630a95e86e7e670da5f06

core/java/android/os/IBinder.java

diff --git a/core/java/android/os/IBinder.java b/core/java/android/os/IBinder.java
index 8a8a6af..fe4de56 100644
--- a/core/java/android/os/IBinder.java
+++ b/core/java/android/os/IBinder.java
@@ -170,6 +170,15 @@
     int FLAG_ONEWAY             = 0x00000001;
 
     /**
+     * Flag to {@link #transact}: request binder driver to clear transaction data.
+     *
+     * Be very careful when using this flag in Java, since Java objects read from a Java
+     * Parcel may be non-trivial to clear.
+     * @hide
+     */
+    int FLAG_CLEAR_BUF          = 0x00000020;
+
+    /**
      * @hide
      */
     int FLAG_COLLECT_NOTED_APP_OPS = 0x00000002;

core/java/android/os/Parcel.java

diff --git a/core/java/android/os/Parcel.java b/core/java/android/os/Parcel.java
index fe70a88..d32a87a 100644
--- a/core/java/android/os/Parcel.java
+++ b/core/java/android/os/Parcel.java
@@ -277,6 +277,8 @@
     private static final int EX_TRANSACTION_FAILED = -129;
 
     @CriticalNative
+    private static native void nativeMarkSensitive(long nativePtr);
+    @CriticalNative
     private static native int nativeDataSize(long nativePtr);
     @CriticalNative
     private static native int nativeDataAvail(long nativePtr);
@@ -491,6 +493,14 @@
     public static native long getGlobalAllocCount();
 
     /**
+     * Parcel data should be zero'd before realloc'd or deleted.
+     * @hide
+     */
+    public final void markSensitive() {
+        nativeMarkSensitive(mNativePtr);
+    }
+
+    /**
      * Returns the total amount of data contained in the parcel.
      */
     public final int dataSize() {

core/jni/android_os_Parcel.cpp

diff --git a/core/jni/android_os_Parcel.cpp b/core/jni/android_os_Parcel.cpp
index 9c7ee0c..241570a 100644
--- a/core/jni/android_os_Parcel.cpp
+++ b/core/jni/android_os_Parcel.cpp
@@ -90,6 +90,14 @@
     env->CallVoidMethod(parcelObj, gParcelOffsets.recycle);
 }
 
+static void android_os_Parcel_markSensitive(jlong nativePtr)
+{
+    Parcel* parcel = reinterpret_cast<Parcel*>(nativePtr);
+    if (parcel) {
+        parcel->markSensitive();
+    }
+}
+
 static jint android_os_Parcel_dataSize(jlong nativePtr)
 {
     Parcel* parcel = reinterpret_cast<Parcel*>(nativePtr);
@@ -758,6 +766,8 @@
 
 static const JNINativeMethod gParcelMethods[] = {
     // @CriticalNative
+    {"nativeMarkSensitive",             "(J)V", (void*)android_os_Parcel_markSensitive},
+    // @CriticalNative
     {"nativeDataSize",            "(J)I", (void*)android_os_Parcel_dataSize},
     // @CriticalNative
     {"nativeDataAvail",           "(J)I", (void*)android_os_Parcel_dataAvail},