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security: improve state restoration safety #13054

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security: improve state restoration safety #13054

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40 changes: 32 additions & 8 deletions app/src/main/java/org/schabi/newpipe/util/StateSaver.java
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Original file line number Diff line number Diff line change
Expand Up @@ -35,8 +35,13 @@
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InvalidClassException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamClass;
import java.io.Serializable;
import java.util.LinkedList;
import java.util.Queue;
import java.util.concurrent.ConcurrentHashMap;
Expand All @@ -63,13 +68,8 @@ private StateSaver() {
* @param context used to get the available cache dir
*/
public static void init(final Context context) {
final File externalCacheDir = context.getExternalCacheDir();
if (externalCacheDir != null) {
cacheDirPath = externalCacheDir.getAbsolutePath();
}
if (TextUtils.isEmpty(cacheDirPath)) {
cacheDirPath = context.getCacheDir().getAbsolutePath();
}
// Use internal cache directory to prevent other apps from accessing/modifying the state
cacheDirPath = context.getCacheDir().getAbsolutePath();
}

/**
Expand Down Expand Up @@ -129,7 +129,7 @@ private static SavedState tryToRestore(@NonNull final SavedState savedState,
}

try (FileInputStream fileInputStream = new FileInputStream(file);
ObjectInputStream inputStream = new ObjectInputStream(fileInputStream)) {
ObjectInputStream inputStream = new ValidatingObjectInputStream(fileInputStream)) {
//noinspection unchecked
savedObjects = (Queue<Object>) inputStream.readObject();
}
Expand Down Expand Up @@ -310,6 +310,30 @@ public static void clearStateFiles() {
}
}

private static final class ValidatingObjectInputStream extends ObjectInputStream {
ValidatingObjectInputStream(final InputStream in) throws IOException {
super(in);
}

@Override
protected Class<?> resolveClass(final ObjectStreamClass desc)
throws IOException, ClassNotFoundException {
final String name = desc.getName();
if (!isSafe(name)) {
throw new InvalidClassException("Unauthorized deserialization attempt", name);
}
return super.resolveClass(desc);
}

private boolean isSafe(final String name) {
return name.startsWith("java.lang.")
|| name.startsWith("java.util.")
|| name.startsWith("org.schabi.newpipe.")
|| name.startsWith("[Ljava.lang.")
|| name.startsWith("[Lorg.schabi.newpipe.");
}
}

/**
* Used for describing how to save/read the objects.
* <p>
Expand Down