From 66acf93106a784172c39e6bbf5c22a1aa3563e0b Mon Sep 17 00:00:00 2001
From: Nikita Ioffe <ioffe@google.com>
Date: Thu, 16 Jun 2022 13:36:35 +0100
Subject: [PATCH] Handle the visibility of sdk sandbox uids

Sdk sandbox processes have the following visibility rules:

1. Sdk sandbox process should be visible to itself
2. Sdk sandbox process should be visible to the corresponding client app
3. Sdk sandbox process shouldn't be visible to anything else

On top of that handle the NPE in the
ComputerEngine.shouldFilterApplication by treating null
PackageStateInternal the same way it is treated in case the calling uid
belongs to the instant app, which is to pretend that null application
exists and that it shouldn't be visible to sdk sandbox.

Bug: 236162773
Test: atest SdkSandboxInprocessTests
Change-Id: Ic2583610f55c36169f9abb35b58a0ab60884a312
Merged-In: Ic2583610f55c36169f9abb35b58a0ab60884a312
---
 .../com/android/server/pm/ComputerEngine.java   | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/services/core/java/com/android/server/pm/ComputerEngine.java b/services/core/java/com/android/server/pm/ComputerEngine.java
index 30de9ba638ccc..259ca655d2b9f 100644
--- a/services/core/java/com/android/server/pm/ComputerEngine.java
+++ b/services/core/java/com/android/server/pm/ComputerEngine.java
@@ -2686,7 +2686,7 @@ public class ComputerEngine implements Computer {
         if (Process.isSdkSandboxUid(callingUid)) {
             int clientAppUid = Process.getAppUidForSdkSandboxUid(callingUid);
             // SDK sandbox should be able to see it's client app
-            if (clientAppUid == UserHandle.getUid(userId, ps.getAppId())) {
+            if (ps != null && clientAppUid == UserHandle.getUid(userId, ps.getAppId())) {
                 return false;
             }
         }
@@ -2698,7 +2698,7 @@ public class ComputerEngine implements Computer {
         final boolean callerIsInstantApp = instantAppPkgName != null;
         if (ps == null) {
             // pretend the application exists, but, needs to be filtered
-            return callerIsInstantApp;
+            return callerIsInstantApp || Process.isSdkSandboxUid(callingUid);
         }
         // if the target and caller are the same application, don't filter
         if (isCallerSameApp(ps.getPackageName(), callingUid)) {
@@ -3089,6 +3089,19 @@ public class ComputerEngine implements Computer {
     }
 
     public boolean filterAppAccess(int uid, int callingUid) {
+        if (Process.isSdkSandboxUid(uid)) {
+            // Sdk sandbox instance should be able to see itself.
+            if (callingUid == uid) {
+                return false;
+            }
+            final int clientAppUid = Process.getAppUidForSdkSandboxUid(uid);
+            // Client app of this sdk sandbox process should be able to see it.
+            if (clientAppUid == uid) {
+                return false;
+            }
+            // Nobody else should be able to see the sdk sandbox process.
+            return true;
+        }
         final int userId = UserHandle.getUserId(uid);
         final int appId = UserHandle.getAppId(uid);
         final Object setting = mSettings.getSettingBase(appId);