From 7ff418d9a9afb9ecf42f87fffd3e65477decb55e Mon Sep 17 00:00:00 2001
From: Jeff Sharkey <jsharkey@android.com>
Date: Wed, 30 Nov 2016 14:29:59 -0700
Subject: [PATCH] Grant MMS Uri permissions as the calling UID.

A recent security fix prevents the system UID from handing out Uri
permission grants directly from itself.  Instead, services need to
issue grants as the original calling UID to ensure that the caller
actually has access to the Uris.

Test: builds, boots, send/recv MMS works in primary/secondary users
Bug: 33231106
Change-Id: Ia9fe19843b52977c8a94ee5349b907beda1882fc
---
 .../java/android/app/ActivityManagerInternal.java |  7 +++++++
 .../java/com/android/server/MmsServiceBroker.java | 15 +++++++++++++--
 .../android/server/am/ActivityManagerService.java |  9 +++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/core/java/android/app/ActivityManagerInternal.java b/core/java/android/app/ActivityManagerInternal.java
index bfa6d349a9f65..913edfd810814 100644
--- a/core/java/android/app/ActivityManagerInternal.java
+++ b/core/java/android/app/ActivityManagerInternal.java
@@ -61,6 +61,13 @@ public abstract class ActivityManagerInternal {
      */
     public static final int APP_TRANSITION_TIMEOUT = 3;
 
+    /**
+     * Grant Uri permissions from one app to another. This method only extends
+     * permission grants if {@code callingUid} has permission to them.
+     */
+    public abstract void grantUriPermissionFromIntent(int callingUid, String targetPkg,
+            Intent intent, int targetUserId);
+
     /**
      * Verify that calling app has access to the given provider.
      */
diff --git a/services/core/java/com/android/server/MmsServiceBroker.java b/services/core/java/com/android/server/MmsServiceBroker.java
index 0414b47e06049..8402087cddae7 100644
--- a/services/core/java/com/android/server/MmsServiceBroker.java
+++ b/services/core/java/com/android/server/MmsServiceBroker.java
@@ -17,6 +17,7 @@
 package com.android.server;
 
 import android.Manifest;
+import android.app.ActivityManagerInternal;
 import android.app.AppOpsManager;
 import android.app.PendingIntent;
 import android.content.ComponentName;
@@ -499,13 +500,21 @@ public class MmsServiceBroker extends SystemService {
          */
         private Uri adjustUriForUserAndGrantPermission(Uri contentUri, String action,
                 int permission) {
+            final Intent grantIntent = new Intent();
+            grantIntent.setData(contentUri);
+            grantIntent.setFlags(permission);
+
+            final int callingUid = Binder.getCallingUid();
             final int callingUserId = UserHandle.getCallingUserId();
             if (callingUserId != UserHandle.USER_SYSTEM) {
                 contentUri = ContentProvider.maybeAddUserId(contentUri, callingUserId);
             }
+
             long token = Binder.clearCallingIdentity();
             try {
-                mContext.grantUriPermission(PHONE_PACKAGE_NAME, contentUri, permission);
+                LocalServices.getService(ActivityManagerInternal.class)
+                        .grantUriPermissionFromIntent(callingUid, PHONE_PACKAGE_NAME,
+                                grantIntent, UserHandle.USER_SYSTEM);
 
                 // Grant permission for the carrier app.
                 Intent intent = new Intent(action);
@@ -514,7 +523,9 @@ public class MmsServiceBroker extends SystemService {
                 List<String> carrierPackages = telephonyManager.getCarrierPackageNamesForIntent(
                         intent);
                 if (carrierPackages != null && carrierPackages.size() == 1) {
-                    mContext.grantUriPermission(carrierPackages.get(0), contentUri, permission);
+                    LocalServices.getService(ActivityManagerInternal.class)
+                            .grantUriPermissionFromIntent(callingUid, carrierPackages.get(0),
+                                    grantIntent, UserHandle.USER_SYSTEM);
                 }
             } finally {
                 Binder.restoreCallingIdentity(token);
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index d085a47294754..2954c26ca07f0 100644
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -22128,6 +22128,15 @@ public class ActivityManagerService extends IActivityManager.Stub
     }
 
     private final class LocalService extends ActivityManagerInternal {
+        @Override
+        public void grantUriPermissionFromIntent(int callingUid, String targetPkg, Intent intent,
+                int targetUserId) {
+            synchronized (ActivityManagerService.this) {
+                ActivityManagerService.this.grantUriPermissionFromIntentLocked(callingUid,
+                        targetPkg, intent, null, targetUserId);
+            }
+        }
+
         @Override
         public String checkContentProviderAccess(String authority, int userId) {
             return ActivityManagerService.this.checkContentProviderAccess(authority, userId);