Test for Checking Package Signatures

Bug 4596332

Check that packages on the device are not signed with well known
keys that may be used by malicious packages to gain privileges.

Change-Id: Id11c31a1c91b79d30d082529cb2a2a99b1f189fe

5 files changed, 128 insertions, 0 deletions

diff --git a/tests/res/raw/sig_media.bin b/tests/res/raw/sig_media.bin
new file mode 100644
index 00000000000..a43bc68a280
--- /dev/null
+++ b/tests/res/raw/sig_media.bin
diff --git a/tests/res/raw/sig_platform.bin b/tests/res/raw/sig_platform.bin
new file mode 100644
index 00000000000..33a683ee8cc
--- /dev/null
+++ b/tests/res/raw/sig_platform.bin
diff --git a/tests/res/raw/sig_shared.bin b/tests/res/raw/sig_shared.bin
new file mode 100644
index 00000000000..094b1b91449
--- /dev/null
+++ b/tests/res/raw/sig_shared.bin
diff --git a/tests/res/raw/sig_testkey.bin b/tests/res/raw/sig_testkey.bin
new file mode 100644
index 00000000000..e2bef19e60e
--- /dev/null
+++ b/tests/res/raw/sig_testkey.bin
diff --git a/tests/tests/security/src/android/security/cts/PackageSignatureTest.java b/tests/tests/security/src/android/security/cts/PackageSignatureTest.java
new file mode 100644
index 00000000000..cff19af80f3
--- /dev/null
+++ b/tests/tests/security/src/android/security/cts/PackageSignatureTest.java
@@ -0,0 +1,128 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.security.cts;
+
+import com.android.cts.stub.R;
+
+import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.PackageManager.NameNotFoundException;
+import android.content.pm.Signature;
+import android.content.res.Resources.NotFoundException;
+import android.test.AndroidTestCase;
+import android.util.Log;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+public class PackageSignatureTest extends AndroidTestCase {
+
+    private static final String TAG = PackageSignatureTest.class.getSimpleName();
+
+    public void testPackageSignatures() throws Exception {
+        Set<String> badPackages = new HashSet<String>();
+        Set<Signature> wellKnownSignatures = getWellKnownSignatures();
+
+        PackageManager packageManager = mContext.getPackageManager();
+        List<PackageInfo> allPackageInfos = packageManager.getInstalledPackages(
+                PackageManager.GET_UNINSTALLED_PACKAGES |
+                PackageManager.GET_SIGNATURES);
+        for (PackageInfo packageInfo : allPackageInfos) {
+            String packageName = packageInfo.packageName;
+            if (packageName != null && !isWhitelistedPackage(packageName)) {
+                for (Signature signature : packageInfo.signatures) {
+                    if (wellKnownSignatures.contains(signature)) {
+                        badPackages.add(packageInfo.packageName);
+                    }
+                }
+            }
+        }
+
+        assertTrue("These packages should not be signed with a well known key: " + badPackages,
+                badPackages.isEmpty());
+    }
+
+    private Set<Signature> getWellKnownSignatures() throws NotFoundException, IOException {
+        Set<Signature> wellKnownSignatures = new HashSet<Signature>();
+        wellKnownSignatures.add(getSignature(R.raw.sig_media));
+        wellKnownSignatures.add(getSignature(R.raw.sig_platform));
+        wellKnownSignatures.add(getSignature(R.raw.sig_shared));
+        wellKnownSignatures.add(getSignature(R.raw.sig_testkey));
+        return wellKnownSignatures;
+    }
+
+    private boolean isWhitelistedPackage(String packageName) {
+        // Don't check the signatures of CTS test packages on the device.
+        // devicesetup is the APK CTS loads to collect information needed in the final report
+        return packageName.startsWith("com.android.cts")
+                || packageName.equalsIgnoreCase("android.tests.devicesetup");
+    }
+
+    private static final int DEFAULT_BUFFER_BYTES = 1024 * 4;
+
+    private Signature getSignature(int resId) throws NotFoundException, IOException {
+        InputStream input = mContext.getResources().openRawResource(resId);
+        ByteArrayOutputStream output = new ByteArrayOutputStream();
+
+        try {
+            byte[] buffer = new byte[DEFAULT_BUFFER_BYTES];
+            int numBytes = 0;
+            while ((numBytes = input.read(buffer)) != -1) {
+                output.write(buffer, 0, numBytes);
+            }
+            return new Signature(output.toByteArray());
+        } finally {
+            input.close();
+            output.close();
+        }
+    }
+
+    /**
+     * Writes a package's signature to a file on the device's external storage.
+     * This method was used to generate the well known signatures used by this test.
+     */
+    @SuppressWarnings("unused")
+    private void writeSignature(String packageName, String fileName)
+            throws NameNotFoundException, IOException {
+        PackageManager packageManager = mContext.getPackageManager();
+        PackageInfo packageInfo = packageManager.getPackageInfo(packageName,
+                PackageManager.GET_SIGNATURES);
+        File directory = mContext.getExternalFilesDir(null);
+        int numSignatures = packageInfo.signatures.length;
+        Log.i(TAG, "Will dump " + numSignatures + " signatures to " + directory);
+        for (int i = 0; i < numSignatures; i++) {
+            Signature signature = packageInfo.signatures[i];
+            byte[] signatureBytes = signature.toByteArray();
+            File signatureFile = new File(directory, fileName + "." + i);
+            FileOutputStream output = null;
+            try {
+                output = new FileOutputStream(signatureFile);
+                output.write(signatureBytes);
+            } finally {
+                if (output != null) {
+                    output.close();
+                }
+            }
+        }
+    }
+}