From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Oli Lan <olilan@google.com>
Date: Mon, 8 Aug 2022 13:31:36 +0100
Subject: [PATCH] RESTRICT AUTOMERGE Prevent non-admin users from deleting
 system apps.

This addresses a security issue where the guest user can remove updates
for system apps.

With this CL, attempts to uninstall/downgrade system apps will fail if
attempted by a non-admin user, unless the DELETE_SYSTEM_APP flag is
specified.

This is a fixed version of ag/17400663, to address b/236578018.

Bug: 170646036
Test: manual, try uninstalling system app update as guest
Change-Id: I5eab215cba6528aa4316ed7b20bee544915c1486
(cherry picked from commit 7fdc96aef4e098d2271ac3a8557bd8e1ad6827f3)
Merged-In: I5eab215cba6528aa4316ed7b20bee544915c1486
---
 .../com/android/server/pm/PackageManagerService.java  | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/services/core/java/com/android/server/pm/PackageManagerService.java b/services/core/java/com/android/server/pm/PackageManagerService.java
index dc44fe17722d..c873f82d740c 100644
--- a/services/core/java/com/android/server/pm/PackageManagerService.java
+++ b/services/core/java/com/android/server/pm/PackageManagerService.java
@@ -18476,6 +18476,17 @@ public class PackageManagerService extends IPackageManager.Stub
                 return PackageManager.DELETE_FAILED_INTERNAL_ERROR;
             }
 
+            if (isSystemApp(uninstalledPs)
+                    && (deleteFlags & PackageManager.DELETE_SYSTEM_APP) == 0) {
+                UserInfo userInfo = sUserManager.getUserInfo(userId);
+                if (userInfo == null || !userInfo.isAdmin()) {
+                    Slog.w(TAG, "Not removing package " + packageName
+                            + " as only admin user may downgrade system apps");
+                    EventLog.writeEvent(0x534e4554, "170646036", -1, packageName);
+                    return PackageManager.DELETE_FAILED_USER_RESTRICTED;
+                }
+            }
+
             // Static shared libs can be declared by any package, so let us not
             // allow removing a package if it provides a lib others depend on.
             pkg = mPackages.get(packageName);
