From 6b0c7acd7f175552d90d1d73b9717ff347158e7d Mon Sep 17 00:00:00 2001
From: Andres Morales <anmorales@google.com>
Date: Mon, 24 Nov 2014 14:14:54 -0800
Subject: [PATCH] Define permission for system apps to query size of block

Allows ManagedProvisioning to determine whether there's a
challenge and thus whether to disable NFC provisioning.

Other implementation option: new hidden boolean API method.
Can't think of benefit of new API method "isBlockInUse", other
than doesn't leak PDB size and is more explicitly tied to the
use case. Open to either impl if anyone has opinions on the matter.

Bug: 18508767
Change-Id: I28d2eb5a0837ff85cb91f140b17ce1dd843fe9d6
---
 core/res/AndroidManifest.xml                                | 6 ++++++
 .../java/com/android/server/PersistentDataBlockService.java | 5 ++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index 3aaecc7a84244..dec7f0790fdff 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -1130,6 +1130,12 @@
                 android:permissionGroup="android.permission-group.SYSTEM_TOOLS"
                 android:protectionLevel="signature" />
 
+    <!-- @hide Allows querying state of PersistentDataBlock
+   <p>Not for use by third-party applications. -->
+    <permission android:name="android.permission.ACCESS_PDB_STATE"
+                android:permissionGroup="android.permission-group.SYSTEM_TOOLS"
+                android:protectionLevel="signature" />
+
 
     <!-- =========================================== -->
     <!-- Permissions associated with audio capture -->
diff --git a/services/core/java/com/android/server/PersistentDataBlockService.java b/services/core/java/com/android/server/PersistentDataBlockService.java
index 17edb5372cdd6..9d4cd99acf8e2 100644
--- a/services/core/java/com/android/server/PersistentDataBlockService.java
+++ b/services/core/java/com/android/server/PersistentDataBlockService.java
@@ -433,7 +433,10 @@ public class PersistentDataBlockService extends SystemService {
 
         @Override
         public int getDataBlockSize() {
-            enforceUid(Binder.getCallingUid());
+            if (mContext.checkCallingPermission(Manifest.permission.ACCESS_PDB_STATE)
+                    != PackageManager.PERMISSION_GRANTED) {
+                enforceUid(Binder.getCallingUid());
+            }
 
             DataInputStream inputStream;
             try {