From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Michael Mikhail <michaelmikhil@google.com>
Date: Fri, 28 Apr 2023 16:17:16 +0000
Subject: [PATCH] Verify URI permissions in MediaMetadata

Add a check for URI permission to make sure that user can access the URI
set in MediaMetadata. If permission is denied, clear the URI string set
in metadata.

Bug: 271851153
Test: atest MediaSessionTest
Test: Verified by POC app attached in bug, image of second user is not
the UMO background of the first user.
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:f95b7fc61d6b3bf49420ded0357bec031f8cbdcf)
Merged-In: I384f8e230c909d8fc8e5f147e2fd3558fec44626
Change-Id: I384f8e230c909d8fc8e5f147e2fd3558fec44626
---
 .../server/media/MediaSessionRecord.java      | 52 +++++++++++++++----
 1 file changed, 43 insertions(+), 9 deletions(-)

diff --git a/services/core/java/com/android/server/media/MediaSessionRecord.java b/services/core/java/com/android/server/media/MediaSessionRecord.java
index e2087e6ca822..5ebbfe92dc20 100644
--- a/services/core/java/com/android/server/media/MediaSessionRecord.java
+++ b/services/core/java/com/android/server/media/MediaSessionRecord.java
@@ -17,6 +17,8 @@
 package com.android.server.media;
 
 import android.app.PendingIntent;
+import android.content.ContentProvider;
+import android.content.ContentResolver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.pm.ParceledListSlice;
@@ -48,11 +50,13 @@ import android.os.Process;
 import android.os.RemoteException;
 import android.os.ResultReceiver;
 import android.os.SystemClock;
+import android.text.TextUtils;
 import android.util.Log;
 import android.util.Slog;
 import android.view.KeyEvent;
 
 import com.android.server.LocalServices;
+import com.android.server.uri.UriGrantsManagerInternal;
 
 import java.io.PrintWriter;
 import java.util.ArrayList;
@@ -64,6 +68,10 @@ import java.util.List;
  */
 public class MediaSessionRecord implements IBinder.DeathRecipient {
     private static final String TAG = "MediaSessionRecord";
+    private static final String[] ART_URIS = new String[] {
+            MediaMetadata.METADATA_KEY_ALBUM_ART_URI,
+            MediaMetadata.METADATA_KEY_ART_URI,
+            MediaMetadata.METADATA_KEY_DISPLAY_ICON_URI};
     private static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);
 
     /**
@@ -85,6 +93,7 @@ public class MediaSessionRecord implements IBinder.DeathRecipient {
     private final SessionStub mSession;
     private final SessionCb mSessionCb;
     private final MediaSessionService mService;
+    private final UriGrantsManagerInternal mUgmInternal;
     private final Context mContext;
 
     private final Object mLock = new Object();
@@ -142,6 +151,7 @@ public class MediaSessionRecord implements IBinder.DeathRecipient {
         mAudioManager = (AudioManager) mContext.getSystemService(Context.AUDIO_SERVICE);
         mAudioManagerInternal = LocalServices.getService(AudioManagerInternal.class);
         mAudioAttrs = new AudioAttributes.Builder().setUsage(AudioAttributes.USAGE_MEDIA).build();
+        mUgmInternal = LocalServices.getService(UriGrantsManagerInternal.class);
     }
 
     /**
@@ -870,21 +880,45 @@ public class MediaSessionRecord implements IBinder.DeathRecipient {
         public void setMetadata(MediaMetadata metadata, long duration, String metadataDescription)
                 throws RemoteException {
             synchronized (mLock) {
-                MediaMetadata temp = metadata == null ? null : new MediaMetadata.Builder(metadata)
-                        .build();
-                // This is to guarantee that the underlying bundle is unparceled
-                // before we set it to prevent concurrent reads from throwing an
-                // exception
-                if (temp != null) {
-                    temp.size();
-                }
-                mMetadata = temp;
                 mDuration = duration;
                 mMetadataDescription = metadataDescription;
+                mMetadata = sanitizeMediaMetadata(metadata);
             }
             mHandler.post(MessageHandler.MSG_UPDATE_METADATA);
         }
 
+        private MediaMetadata sanitizeMediaMetadata(MediaMetadata metadata) {
+            if (metadata == null) {
+                return null;
+            }
+            MediaMetadata.Builder metadataBuilder = new MediaMetadata.Builder(metadata);
+            for (String key: ART_URIS) {
+                String uriString = metadata.getString(key);
+                if (TextUtils.isEmpty(uriString)) {
+                    continue;
+                }
+                Uri uri = Uri.parse(uriString);
+                if (!ContentResolver.SCHEME_CONTENT.equals(uri.getScheme())) {
+                    continue;
+                }
+                try {
+                    mUgmInternal.checkGrantUriPermission(getUid(),
+                            getPackageName(),
+                            ContentProvider.getUriWithoutUserId(uri),
+                            Intent.FLAG_GRANT_READ_URI_PERMISSION,
+                            ContentProvider.getUserIdFromUri(uri, getUserId()));
+                } catch (SecurityException e) {
+                    metadataBuilder.putString(key, null);
+                }
+            }
+            MediaMetadata sanitizedMetadata = metadataBuilder.build();
+            // sanitizedMetadata.size() guarantees that the underlying bundle is unparceled
+            // before we set it to prevent concurrent reads from throwing an
+            // exception
+            sanitizedMetadata.size();
+            return sanitizedMetadata;
+        }
+
         @Override
         public void setPlaybackState(PlaybackState state) throws RemoteException {
             int oldState = mPlaybackState == null
