am 648f8106: am db3d76ab: Merge "Fix ParceledListSlice to enforce the same... (ffd4785e) · Commits · e / os / android_frameworks_base

core/java/android/content/pm/ParceledListSlice.java

+43 −4

Original line number	Diff line number	Diff line
		@@ -30,6 +30,12 @@ import java.util.List;
		* Transfer a large list of Parcelable objects across an IPC. Splits into
		* multiple transactions if needed.
		*
		* Caveat: for efficiency and security, all elements must be the same concrete type.
		* In order to avoid writing the class name of each object, we must ensure that
		* each object is the same type, or else unparceling then reparceling the data may yield
		* a different result if the class name encoded in the Parcelable is a Base type.
		* See b/17671747.
		*
		* @hide
		*/
		public class ParceledListSlice<T extends Parcelable> implements Parcelable {
		@@ -56,13 +62,25 @@ public class ParceledListSlice<T extends Parcelable> implements Parcelable {
		if (N <= 0) {
		return;
		}

		Parcelable.Creator<T> creator = p.readParcelableCreator(loader);
		Class<?> listElementClass = null;

		int i = 0;
		while (i < N) {
		if (p.readInt() == 0) {
		break;
		}
		mList.add(p.readCreator(creator, loader));

		final T parcelable = p.readCreator(creator, loader);
		if (listElementClass == null) {
		listElementClass = parcelable.getClass();
		} else {
		verifySameType(listElementClass, parcelable.getClass());
		}

		mList.add(parcelable);

		if (DEBUG) Log.d(TAG, "Read inline #" + i + ": " + mList.get(mList.size()-1));
		i++;
		}
		@@ -82,7 +100,11 @@ public class ParceledListSlice<T extends Parcelable> implements Parcelable {
		return;
		}
		while (i < N && reply.readInt() != 0) {
		mList.add(reply.readCreator(creator, loader));
		final T parcelable = reply.readCreator(creator, loader);
		verifySameType(listElementClass, parcelable.getClass());

		mList.add(parcelable);

		if (DEBUG) Log.d(TAG, "Read extra #" + i + ": " + mList.get(mList.size()-1));
		i++;
		}
		@@ -91,6 +113,14 @@ public class ParceledListSlice<T extends Parcelable> implements Parcelable {
		}
		}

		private static void verifySameType(final Class<?> expected, final Class<?> actual) {
		if (!actual.equals(expected)) {
		throw new IllegalArgumentException("Can't unparcel type "
		+ actual.getName() + " in list of type "
		+ expected.getName());
		}
		}

		public List<T> getList() {
		return mList;
		}
		@@ -116,11 +146,16 @@ public class ParceledListSlice<T extends Parcelable> implements Parcelable {
		dest.writeInt(N);
		if (DEBUG) Log.d(TAG, "Writing " + N + " items");
		if (N > 0) {
		final Class<?> listElementClass = mList.get(0).getClass();
		dest.writeParcelableCreator(mList.get(0));
		int i = 0;
		while (i < N && dest.dataSize() < MAX_FIRST_IPC_SIZE) {
		dest.writeInt(1);
		mList.get(i).writeToParcel(dest, callFlags);

		final T parcelable = mList.get(i);
		verifySameType(listElementClass, parcelable.getClass());
		parcelable.writeToParcel(dest, callFlags);

		if (DEBUG) Log.d(TAG, "Wrote inline #" + i + ": " + mList.get(i));
		i++;
		}
		@@ -137,7 +172,11 @@ public class ParceledListSlice<T extends Parcelable> implements Parcelable {
		if (DEBUG) Log.d(TAG, "Writing more @" + i + " of " + N);
		while (i < N && reply.dataSize() < MAX_IPC_SIZE) {
		reply.writeInt(1);
		mList.get(i).writeToParcel(reply, callFlags);

		final T parcelable = mList.get(i);
		verifySameType(listElementClass, parcelable.getClass());
		parcelable.writeToParcel(reply, callFlags);

		if (DEBUG) Log.d(TAG, "Wrote extra #" + i + ": " + mList.get(i));
		i++;
		}

core/tests/coretests/src/android/content/pm/ParceledListSliceTest.java

0 → 100644

+263 −0

Original line number	Diff line number	Diff line
		package android.content.pm;

		import android.os.Parcel;
		import android.os.Parcelable;
		import junit.framework.TestCase;

		import java.util.ArrayList;
		import java.util.List;

		public class ParceledListSliceTest extends TestCase {

		public void testSmallList() throws Exception {
		final int objectCount = 100;
		List<SmallObject> list = new ArrayList<>();
		for (int i = 0; i < objectCount; i++) {
		list.add(new SmallObject(i * 2, (i * 2) + 1));
		}

		ParceledListSlice<SmallObject> slice;

		Parcel parcel = Parcel.obtain();
		try {
		parcel.writeParcelable(new ParceledListSlice<>(list), 0);
		parcel.setDataPosition(0);
		slice = parcel.readParcelable(getClass().getClassLoader());
		} finally {
		parcel.recycle();
		}

		assertNotNull(slice);
		assertNotNull(slice.getList());
		assertEquals(objectCount, slice.getList().size());

		for (int i = 0; i < objectCount; i++) {
		assertEquals(i * 2, slice.getList().get(i).mFieldA);
		assertEquals((i * 2) + 1, slice.getList().get(i).mFieldB);
		}
		}

		private static int measureLargeObject() {
		Parcel p = Parcel.obtain();
		try {
		new LargeObject(0, 0, 0, 0, 0).writeToParcel(p, 0);
		return p.dataPosition();
		} finally {
		p.recycle();
		}
		}

		/**
		* Test that when the list is large, the data is successfully parceled
		* and unparceled (the implementation will send pieces of the list in
		* separate round-trips to avoid the IPC limit).
		*/
		public void testLargeList() throws Exception {
		final int thresholdBytes = 256 * 1024;
		final int objectCount = thresholdBytes / measureLargeObject();

		List<LargeObject> list = new ArrayList<>();
		for (int i = 0; i < objectCount; i++) {
		list.add(new LargeObject(
		i * 5,
		(i * 5) + 1,
		(i * 5) + 2,
		(i * 5) + 3,
		(i * 5) + 4
		));
		}

		ParceledListSlice<LargeObject> slice;

		Parcel parcel = Parcel.obtain();
		try {
		parcel.writeParcelable(new ParceledListSlice<>(list), 0);
		parcel.setDataPosition(0);
		slice = parcel.readParcelable(getClass().getClassLoader());
		} finally {
		parcel.recycle();
		}

		assertNotNull(slice);
		assertNotNull(slice.getList());
		assertEquals(objectCount, slice.getList().size());

		for (int i = 0; i < objectCount; i++) {
		assertEquals(i * 5, slice.getList().get(i).mFieldA);
		assertEquals((i * 5) + 1, slice.getList().get(i).mFieldB);
		assertEquals((i * 5) + 2, slice.getList().get(i).mFieldC);
		assertEquals((i * 5) + 3, slice.getList().get(i).mFieldD);
		assertEquals((i * 5) + 4, slice.getList().get(i).mFieldE);
		}
		}

		/**
		* Test that only homogeneous elements may be unparceled.
		*/
		public void testHomogeneousElements() throws Exception {
		List<BaseObject> list = new ArrayList<>();
		list.add(new LargeObject(0, 1, 2, 3, 4));
		list.add(new SmallObject(5, 6));
		list.add(new SmallObject(7, 8));

		Parcel parcel = Parcel.obtain();
		try {
		writeEvilParceledListSlice(parcel, list);
		parcel.setDataPosition(0);
		try {
		ParceledListSlice.CREATOR.createFromParcel(parcel, getClass().getClassLoader());
		assertTrue("Unparceled heterogeneous ParceledListSlice", false);
		} catch (IllegalArgumentException e) {
		// Success, we're not allowed to process heterogeneous
		// elements in a ParceledListSlice.
		}
		} finally {
		parcel.recycle();
		}
		}

		/**
		* Write a ParcelableListSlice that uses the BaseObject base class as the Creator.
		* This is dangerous, as it may affect how the data is unparceled, then later parceled
		* by the system, leading to a self-modifying data security vulnerability.
		*/
		private static <T extends BaseObject> void writeEvilParceledListSlice(Parcel dest, List<T> list) {
		final int listCount = list.size();

		// Number of items.
		dest.writeInt(listCount);

		// The type/creator to use when unparceling. Here we use the base class
		// to simulate an attack on ParceledListSlice.
		dest.writeString(BaseObject.class.getName());

		for (int i = 0; i < listCount; i++) {
		// 1 means the item is present.
		dest.writeInt(1);
		list.get(i).writeToParcel(dest, 0);
		}
		}

		public abstract static class BaseObject implements Parcelable {
		protected static final int TYPE_SMALL = 0;
		protected static final int TYPE_LARGE = 1;

		protected void writeToParcel(Parcel dest, int flags, int type) {
		dest.writeInt(type);
		}

		@Override
		public int describeContents() {
		return 0;
		}

		/**
		* This is REALLY bad, but we're doing it in the test to ensure that we handle
		* the possible exploit when unparceling an object with the BaseObject written as
		* Creator.
		*/
		public static final Creator<BaseObject> CREATOR = new Creator<BaseObject>() {
		@Override
		public BaseObject createFromParcel(Parcel source) {
		switch (source.readInt()) {
		case TYPE_SMALL:
		return SmallObject.createFromParcelBody(source);
		case TYPE_LARGE:
		return LargeObject.createFromParcelBody(source);
		default:
		throw new IllegalArgumentException("Unknown type");
		}
		}

		@Override
		public BaseObject[] newArray(int size) {
		return new BaseObject[size];
		}
		};
		}

		public static class SmallObject extends BaseObject {
		public int mFieldA;
		public int mFieldB;

		public SmallObject(int a, int b) {
		mFieldA = a;
		mFieldB = b;
		}

		@Override
		public void writeToParcel(Parcel dest, int flags) {
		super.writeToParcel(dest, flags, TYPE_SMALL);
		dest.writeInt(mFieldA);
		dest.writeInt(mFieldB);
		}

		public static SmallObject createFromParcelBody(Parcel source) {
		return new SmallObject(source.readInt(), source.readInt());
		}

		public static final Creator<SmallObject> CREATOR = new Creator<SmallObject>() {
		@Override
		public SmallObject createFromParcel(Parcel source) {
		// Consume the type (as it is always written out).
		source.readInt();
		return createFromParcelBody(source);
		}

		@Override
		public SmallObject[] newArray(int size) {
		return new SmallObject[size];
		}
		};
		}

		public static class LargeObject extends BaseObject {
		public int mFieldA;
		public int mFieldB;
		public int mFieldC;
		public int mFieldD;
		public int mFieldE;

		public LargeObject(int a, int b, int c, int d, int e) {
		mFieldA = a;
		mFieldB = b;
		mFieldC = c;
		mFieldD = d;
		mFieldE = e;
		}

		@Override
		public void writeToParcel(Parcel dest, int flags) {
		super.writeToParcel(dest, flags, TYPE_LARGE);
		dest.writeInt(mFieldA);
		dest.writeInt(mFieldB);
		dest.writeInt(mFieldC);
		dest.writeInt(mFieldD);
		dest.writeInt(mFieldE);
		}

		public static LargeObject createFromParcelBody(Parcel source) {
		return new LargeObject(
		source.readInt(),
		source.readInt(),
		source.readInt(),
		source.readInt(),
		source.readInt()
		);
		}

		public static final Creator<LargeObject> CREATOR = new Creator<LargeObject>() {
		@Override
		public LargeObject createFromParcel(Parcel source) {
		// Consume the type (as it is always written out).
		source.readInt();
		return createFromParcelBody(source);
		}

		@Override
		public LargeObject[] newArray(int size) {
		return new LargeObject[size];
		}
		};
		}
		}