Merge "RRO: remove ability to overlay assets"

core/tests/overlaytests/device/assets/package-name.txt

@@ -0,0 +1 @@
+com.android.overlaytest

core/tests/overlaytests/device/src/com/android/overlaytest/OverlayBaseTest.java

@@ -17,9 +17,12 @@
 package com.android.overlaytest;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
 import android.app.UiAutomation;
+import android.content.res.AssetManager;
 import android.content.res.Configuration;
 import android.content.res.Resources;
 import android.content.res.XmlResourceParser;
@@ -30,6 +33,8 @@ import android.util.Xml;
 
 import androidx.test.InstrumentationRegistry;
 
+import com.android.internal.util.ArrayUtils;
+
 import org.junit.Before;
 import org.junit.Ignore;
 import org.junit.Test;
@@ -291,6 +296,33 @@ public abstract class OverlayBaseTest {
         assertEquals(getExpected(no, so, mo), actual);
     }
 
+    @Test
+    public void testAssetsNotPossibleToOverlay() throws Throwable {
+        final AssetManager am = mResources.getAssets();
+
+        // AssetManager#list will include assets from all loaded non-overlay
+        // APKs, including the framework; framework-res.apk contains at least
+        // assets/{images,webkit}. Rather than checking the list, verify that
+        // assets only present in overlays are never part of the list.
+        String[] files = am.list("");
+        assertTrue(ArrayUtils.contains(files, "package-name.txt"));
+        assertFalse(ArrayUtils.contains(files, "foo.txt"));
+        assertFalse(ArrayUtils.contains(files, "bar.txt"));
+
+        String contents = null;
+        try (InputStream is = am.open("package-name.txt")) {
+            final BufferedReader reader = new BufferedReader(
+                    new InputStreamReader(is, StandardCharsets.UTF_8));
+            StringBuilder str = new StringBuilder();
+            String line;
+            while ((line = reader.readLine()) != null) {
+                str.append(line);
+            }
+            contents = str.toString();
+        }
+        assertEquals("com.android.overlaytest", contents);
+    }
+
     /*
      * testMatrix* tests
      *

core/tests/overlaytests/device/test-apps/AppOverlayOne/assets/foo.txt

@@ -0,0 +1 @@
+foo

core/tests/overlaytests/device/test-apps/AppOverlayOne/assets/package-name.txt

@@ -0,0 +1 @@
+com.android.overlaytest.app_overlay_one

core/tests/overlaytests/device/test-apps/AppOverlayTwo/assets/bar.txt

@@ -0,0 +1 @@
+bar

core/tests/overlaytests/device/test-apps/AppOverlayTwo/assets/package-name.txt

@@ -0,0 +1 @@
+com.android.overlaytest.app_overlay_two

libs/androidfw/AssetManager2.cpp

@@ -310,6 +310,9 @@ std::unique_ptr<AssetDir> AssetManager2::OpenDir(const std::string& dirname) con
   // Start from the back.
   for (auto iter = apk_assets_.rbegin(); iter != apk_assets_.rend(); ++iter) {
     const ApkAssets* apk_assets = *iter;
+    if (apk_assets->IsOverlay()) {
+      continue;
+    }
 
     auto func = [&](const StringPiece& name, FileType type) {
       AssetDir::FileInfo info;
@@ -336,6 +339,13 @@ std::unique_ptr<Asset> AssetManager2::OpenNonAsset(const std::string& filename,
                                                    Asset::AccessMode mode,
                                                    ApkAssetsCookie* out_cookie) const {
   for (int32_t i = apk_assets_.size() - 1; i >= 0; i--) {
+    // Prevent RRO from modifying assets and other entries accessed by file
+    // path. Explicitly asking for a path in a given package (denoted by a
+    // cookie) is still OK.
+    if (apk_assets_[i]->IsOverlay()) {
+      continue;
+    }
+
     std::unique_ptr<Asset> asset = apk_assets_[i]->Open(filename, mode);
     if (asset) {
       if (out_cookie != nullptr) {

libs/androidfw/include/androidfw/ApkAssets.h

@@ -80,6 +80,10 @@ class ApkAssets {
     return loaded_arsc_.get();
   }
 
+  inline bool IsOverlay() const {
+    return idmap_asset_.get() != nullptr;
+  }
+
  private:
   DISALLOW_COPY_AND_ASSIGN(ApkAssets);