From 89a3a0102026ad3621a89b0f1c3b25eb3ad49329 Mon Sep 17 00:00:00 2001
From: Andy CrossGate Yan <GeForce8800Ultra@gmail.com>
Date: Fri, 17 May 2019 03:36:35 +0000
Subject: [PATCH] core: Add support for MicroG

-fake signatures, enabled per app by dynamic permission

Change-Id: I0e5a0aca9fccbd4372de8ce3af76c53cc7c35f28
---
 core/res/AndroidManifest.xml                  |  7 ++++++
 core/res/res/values/config.xml                |  2 ++
 core/res/res/values/strings.xml               |  5 ++++
 .../server/pm/PackageManagerService.java      | 23 +++++++++++++++++--
 4 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index af1a6fa9e3c..c9e9daea1ba 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -2357,6 +2357,13 @@
         android:description="@string/permdesc_getPackageSize"
         android:protectionLevel="normal" />
 
+    <!-- @hide Allows an application to change the package signature as
+	 seen by applications -->
+    <permission android:name="android.permission.FAKE_PACKAGE_SIGNATURE"
+        android:protectionLevel="dangerous"
+        android:label="@string/permlab_fakePackageSignature"
+        android:description="@string/permdesc_fakePackageSignature" />
+
     <!-- @deprecated No longer useful, see
          {@link android.content.pm.PackageManager#addPackageToPreferred}
          for details. -->
diff --git a/core/res/res/values/config.xml b/core/res/res/values/config.xml
index bd84a6d720b..977ae5cfe10 100644
--- a/core/res/res/values/config.xml
+++ b/core/res/res/values/config.xml
@@ -1716,6 +1716,8 @@
     <string-array name="config_locationProviderPackageNames" translatable="false">
         <!-- The standard AOSP fused location provider -->
         <item>com.android.location.fused</item>
+        <!-- The (faked) microg fused location provider (a free reimplementation) -->
+        <item>com.google.android.gms</item>
     </string-array>
 
     <!-- This string array can be overriden to enable test location providers initially. -->
diff --git a/core/res/res/values/strings.xml b/core/res/res/values/strings.xml
index f6600462ea7..bd96a09684f 100644
--- a/core/res/res/values/strings.xml
+++ b/core/res/res/values/strings.xml
@@ -785,6 +785,11 @@
 
     <!--  Permissions -->
 
+    <!-- Title of an application permission, listed so the user can choose whether they want to allow the application to do this. -->
+    <string name="permlab_fakePackageSignature">Spoof package signature</string>
+    <!-- Description of an application permission, listed so the user can choose whether they want to allow the application to do this. -->
+    <string name="permdesc_fakePackageSignature">Allows the app to pretend to be a different app. Malicious applications might be able to use this to access private application data. Legitimate uses include an emulator pretending to be what it emulates. Grant this permission with caution only!</string>
+
     <!-- Title of an application permission, listed so the user can choose whether they want to allow the application to do this. -->
     <string name="permlab_statusBar">disable or modify status bar</string>
     <!-- Description of an application permission, listed so the user can choose whether they want to allow the application to do this. -->
diff --git a/services/core/java/com/android/server/pm/PackageManagerService.java b/services/core/java/com/android/server/pm/PackageManagerService.java
index f3938b32333..1b069e34891 100644
--- a/services/core/java/com/android/server/pm/PackageManagerService.java
+++ b/services/core/java/com/android/server/pm/PackageManagerService.java
@@ -4063,8 +4063,9 @@ public class PackageManagerService extends IPackageManager.Stub
                 });
             }
 
-            PackageInfo packageInfo = PackageParser.generatePackageInfo(p, gids, flags,
-                    ps.firstInstallTime, ps.lastUpdateTime, permissions, state, userId);
+            PackageInfo packageInfo = mayFakeSignature(p, PackageParser.generatePackageInfo(p, gids, flags,
+                ps.firstInstallTime, ps.lastUpdateTime, permissions, state, userId),
+                permissions);
 
             if (packageInfo == null) {
                 return null;
@@ -4100,6 +4101,24 @@ public class PackageManagerService extends IPackageManager.Stub
         }
     }
 
+    private PackageInfo mayFakeSignature(PackageParser.Package p, PackageInfo pi,
+            Set<String> permissions) {
+        try {
+            if (permissions.contains("android.permission.FAKE_PACKAGE_SIGNATURE")
+                    && p.applicationInfo.targetSdkVersion > Build.VERSION_CODES.LOLLIPOP_MR1
+                    && p.mAppMetaData != null) {
+                String sig = p.mAppMetaData.getString("fake-signature");
+                if (sig != null) {
+                    pi.signatures = new Signature[] {new Signature(sig)};
+                }
+            }
+        } catch (Throwable t) {
+            // We should never die because of any failures, this is system code!
+            Log.w("PackageManagerService.FAKE_PACKAGE_SIGNATURE", t);
+	}
+        return pi;
+    }
+
     @Override
     public void checkPackageStartable(String packageName, int userId) {
         final int callingUid = Binder.getCallingUid();
-- 
2.25.1