From c9b266ded8a63da3408c24479100ea53baf455b7 Mon Sep 17 00:00:00 2001
From: gudenau <gudenau>
Date: Tue, 25 Sep 2018 09:44:26 +0200
Subject: [PATCH] core: Add support for MicroG

-fake signatures, enabled per app by dynamic permission

Change-Id: I84fc7e5c606f4b57012d948a4cc6cb521db6b03e
---
 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 0c3b7a137b9..fc6f9d9a1ec 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -2637,6 +2637,13 @@
         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 91f4cf3093e..91fb69f8066 100644
--- a/core/res/res/values/config.xml
+++ b/core/res/res/values/config.xml
@@ -1856,6 +1856,8 @@
     <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 152b131af8f..f8d87a37064 100644
--- a/core/res/res/values/strings.xml
+++ b/core/res/res/values/strings.xml
@@ -827,6 +827,11 @@
 
     <!--  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 fb672a5231f..d5878ed9fc4 100644
--- a/services/core/java/com/android/server/pm/PackageManagerService.java
+++ b/services/core/java/com/android/server/pm/PackageManagerService.java
@@ -4111,8 +4111,9 @@ public class PackageManagerService extends IPackageManager.Stub
             final Set<String> permissions = ArrayUtils.isEmpty(p.requestedPermissions)
                     ? Collections.emptySet() : permissionsState.getPermissions(userId);
 
-            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;
@@ -4148,6 +4149,24 @@ 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();
-- 
2.17.1