Java: Add support and tests for implicitly exported activity aliases

Author: egregius313

java/ql/lib/semmle/code/java/frameworks/android/Android.qll

@@ -57,6 +57,12 @@ class ExportableAndroidComponent extends AndroidComponent {
     or
     this.hasIntentFilter() and
     not this.getAndroidComponentXmlElement().isNotExported()
+    or
+    exists(AndroidActivityAliasXmlElement e |
+      e = this.getAndroidComponentXmlElement() and
+      not e.isNotExported() and
+      e.hasAnIntentFilterElement()
+    )
   }
 }
 

java/ql/test/library-tests/frameworks/android/activity-alias/AndroidManifest.xml

@@ -52,7 +52,34 @@
             android:exported="true"
             android:label="@string/app_name"
             android:targetActivity="com.example.myapplication.AnotherActivity"></activity-alias>
+        <activity
+            android:name=".ExampleActivity"
+            android:exported="false"
+            android:label="@string/app_name"
+            ></activity>
 
+        <activity-alias
+            android:name=".ExampleAlias"
+            android:exported="true"
+            android:label="@string/app_name"
+            android:targetActivity=".ExampleActivity">
+        </activity-alias>
+
+        <activity
+            android:name=".Example2Activity"
+            android:exported="false"
+            android:label="@string/app_name">
+        </activity>
+
+        <activity-alias
+            android:name=".Example2Alias"
+            android:label="@string/app_name"
+            android:targetActivity=".Example2Activity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"></action>
+                <action android:name="android.intent.category.LAUNCHER"></action>
+            </intent-filter>
+        </activity-alias>
     </application>
 
 </manifest>

java/ql/test/library-tests/frameworks/android/activity-alias/Example2Activity.java

@@ -0,0 +1,7 @@
+package com.example.myapplication;
+
+import android.app.Activity;
+
+public class Example2Activity extends Activity {
+
+}

java/ql/test/library-tests/frameworks/android/activity-alias/ExampleActivity.java

@@ -0,0 +1,7 @@
+package com.example.myapplication;
+
+import android.app.Activity;
+
+public class ExampleActivity extends Activity {
+
+}

java/ql/test/library-tests/frameworks/android/activity-alias/TestActivityAlias.expected

@@ -1,3 +1,5 @@
 | .AnotherAlias | .AnotherActivity |
+| .Example2Alias | .Example2Activity |
+| .ExampleAlias | .ExampleActivity |
 | .MainAlias | .MainActivity |
 | .SecondAlias | .MainActivity |

java/ql/test/library-tests/frameworks/android/activity-alias/TestActivityAliasExports.expected

@@ -0,0 +1,4 @@
+| Example2Activity.java:5:14:5:29 | Example2Activity | AndroidManifest.xml:68:9:72:20 | activity |
+| Example2Activity.java:5:14:5:29 | Example2Activity | AndroidManifest.xml:74:9:82:26 | activity-alias |
+| ExampleActivity.java:5:14:5:28 | ExampleActivity | AndroidManifest.xml:55:9:59:25 | activity |
+| ExampleActivity.java:5:14:5:28 | ExampleActivity | AndroidManifest.xml:61:9:66:26 | activity-alias |

java/ql/test/library-tests/frameworks/android/activity-alias/TestActivityAliasExports.ql

@@ -0,0 +1,6 @@
+import java
+import semmle.code.java.frameworks.android.Android
+
+from ExportableAndroidComponent component
+where component.isExported()
+select component, component.getAndroidComponentXmlElement()

java/ql/test/library-tests/frameworks/android/activity-alias/options

@@ -0,0 +1 @@
+//semmle-extractor-options: --javac-args -cp ${testdir}/../../../../stubs/google-android-9.0.0/