Add restriction to remove main user

Add restriction to remove main user when system property
MAIN_USER_PERMANENT_ADMIN is set to true.

Bug: 260200162
Test: atest UserManagerTest -c
Change-Id: Ibce0d8275eed131fad794503924d52ad31b540c2

5 files changed, 82 insertions, 7 deletions

diff --git a/core/api/system-current.txt b/core/api/system-current.txt
index 712ac94216d3..3bb90f7801aa 100644
--- a/core/api/system-current.txt
+++ b/core/api/system-current.txt
@@ -10380,6 +10380,7 @@ package android.os {
     field public static final String DISALLOW_RUN_IN_BACKGROUND = "no_run_in_background";
     field public static final int REMOVE_RESULT_ALREADY_BEING_REMOVED = 2; // 0x2
     field public static final int REMOVE_RESULT_DEFERRED = 1; // 0x1
+    field public static final int REMOVE_RESULT_ERROR_MAIN_USER_PERMANENT_ADMIN = -5; // 0xfffffffb
     field public static final int REMOVE_RESULT_ERROR_SYSTEM_USER = -4; // 0xfffffffc
     field public static final int REMOVE_RESULT_ERROR_UNKNOWN = -1; // 0xffffffff
     field public static final int REMOVE_RESULT_ERROR_USER_NOT_FOUND = -3; // 0xfffffffd
diff --git a/core/java/android/os/UserManager.java b/core/java/android/os/UserManager.java
index 99152347106f..73e52a799cef 100644
--- a/core/java/android/os/UserManager.java
+++ b/core/java/android/os/UserManager.java
@@ -1824,6 +1824,15 @@ public class UserManager {
     public static final int REMOVE_RESULT_ERROR_SYSTEM_USER = -4;
 
     /**
+     * A response code from {@link #removeUserWhenPossible(UserHandle, boolean)} indicating that
+     * user being removed is a  {@link UserInfo#FLAG_MAIN}  user and can't be removed because
+     * system property {@link com.android.internal.R.bool.isMainUserPermanentAdmin} is true.
+     * @hide
+     */
+    @SystemApi
+    public static final int REMOVE_RESULT_ERROR_MAIN_USER_PERMANENT_ADMIN = -5;
+
+    /**
      * Possible response codes from {@link #removeUserWhenPossible(UserHandle, boolean)}.
      *
      * @hide
@@ -1835,6 +1844,7 @@ public class UserManager {
             REMOVE_RESULT_ERROR_USER_RESTRICTION,
             REMOVE_RESULT_ERROR_USER_NOT_FOUND,
             REMOVE_RESULT_ERROR_SYSTEM_USER,
+            REMOVE_RESULT_ERROR_MAIN_USER_PERMANENT_ADMIN,
             REMOVE_RESULT_ERROR_UNKNOWN,
     })
     @Retention(RetentionPolicy.SOURCE)
@@ -5224,8 +5234,9 @@ public class UserManager {
      * @return the {@link RemoveResult} code: {@link #REMOVE_RESULT_REMOVED},
      * {@link #REMOVE_RESULT_DEFERRED}, {@link #REMOVE_RESULT_ALREADY_BEING_REMOVED},
      * {@link #REMOVE_RESULT_ERROR_USER_RESTRICTION}, {@link #REMOVE_RESULT_ERROR_USER_NOT_FOUND},
-     * {@link #REMOVE_RESULT_ERROR_SYSTEM_USER}, or {@link #REMOVE_RESULT_ERROR_UNKNOWN}. All error
-     * codes have negative values.
+     * {@link #REMOVE_RESULT_ERROR_SYSTEM_USER},
+     * {@link #REMOVE_RESULT_ERROR_MAIN_USER_PERMANENT_ADMIN}, or
+     * {@link #REMOVE_RESULT_ERROR_UNKNOWN}. All error codes have negative values.
      *
      * @hide
      */
diff --git a/services/core/java/com/android/server/pm/PackageManagerShellCommand.java b/services/core/java/com/android/server/pm/PackageManagerShellCommand.java
index 2138c205ee58..55bc0f416846 100644
--- a/services/core/java/com/android/server/pm/PackageManagerShellCommand.java
+++ b/services/core/java/com/android/server/pm/PackageManagerShellCommand.java
@@ -3012,6 +3012,10 @@ class PackageManagerShellCommand extends ShellCommand {
             case UserManager.REMOVE_RESULT_ALREADY_BEING_REMOVED:
                 getOutPrintWriter().printf("Success: user %d is already being removed\n", userId);
                 return 0;
+            case UserManager.REMOVE_RESULT_ERROR_MAIN_USER_PERMANENT_ADMIN:
+                getOutPrintWriter().printf("Error: user %d is a permanent admin main user\n",
+                        userId);
+                return 1;
             default:
                 getErrPrintWriter().printf("Error: couldn't remove or mark ephemeral user id %d\n",
                         userId);
diff --git a/services/core/java/com/android/server/pm/UserManagerService.java b/services/core/java/com/android/server/pm/UserManagerService.java
index 6bac90532645..b4d35a17fb1f 100644
--- a/services/core/java/com/android/server/pm/UserManagerService.java
+++ b/services/core/java/com/android/server/pm/UserManagerService.java
@@ -5426,6 +5426,12 @@ public class UserManagerService extends IUserManager.Stub {
                         return false;
                     }
 
+                    if (isNonRemovableMainUser(userData.info)) {
+                        Slog.e(LOG_TAG, "Main user cannot be removed when "
+                                + "it's a permanent admin user.");
+                        return false;
+                    }
+
                     if (mRemovingUserIds.get(userId)) {
                         Slog.e(LOG_TAG, TextUtils.formatSimple(
                                 "User %d is already scheduled for removal.", userId));
@@ -5530,6 +5536,12 @@ public class UserManagerService extends IUserManager.Stub {
                         return UserManager.REMOVE_RESULT_ERROR_USER_NOT_FOUND;
                     }
 
+                    if (isNonRemovableMainUser(userData.info)) {
+                        Slog.e(LOG_TAG, "Main user cannot be removed when "
+                                + "it's a permanent admin user.");
+                        return UserManager.REMOVE_RESULT_ERROR_MAIN_USER_PERMANENT_ADMIN;
+                    }
+
                     if (mRemovingUserIds.get(userId)) {
                         Slog.e(LOG_TAG, "User " + userId + " is already scheduled for removal.");
                         return UserManager.REMOVE_RESULT_ALREADY_BEING_REMOVED;
@@ -6748,7 +6760,7 @@ public class UserManagerService extends IUserManager.Stub {
         public void removeAllUsers() {
             if (UserHandle.USER_SYSTEM == getCurrentUserId()) {
                 // Remove the non-system users straight away.
-                removeNonSystemUsers();
+                removeAllUsersExceptSystemAndPermanentAdminMain();
             } else {
                 // Switch to the system user first and then remove the other users.
                 BroadcastReceiver userSwitchedReceiver = new BroadcastReceiver() {
@@ -6760,7 +6772,7 @@ public class UserManagerService extends IUserManager.Stub {
                             return;
                         }
                         mContext.unregisterReceiver(this);
-                        removeNonSystemUsers();
+                        removeAllUsersExceptSystemAndPermanentAdminMain();
                     }
                 };
                 IntentFilter userSwitchedFilter = new IntentFilter();
@@ -7113,14 +7125,14 @@ public class UserManagerService extends IUserManager.Stub {
         throw new UserManager.CheckedUserOperationException(message, userOperationResult);
     }
 
-    /* Remove all the users except of the system one. */
-    private void removeNonSystemUsers() {
+    /* Remove all the users except the system and permanent admin main.*/
+    private void removeAllUsersExceptSystemAndPermanentAdminMain() {
         ArrayList<UserInfo> usersToRemove = new ArrayList<>();
         synchronized (mUsersLock) {
             final int userSize = mUsers.size();
             for (int i = 0; i < userSize; i++) {
                 UserInfo ui = mUsers.valueAt(i).info;
-                if (ui.id != UserHandle.USER_SYSTEM) {
+                if (ui.id != UserHandle.USER_SYSTEM && !isNonRemovableMainUser(ui)) {
                     usersToRemove.add(ui);
                 }
             }
@@ -7249,4 +7261,22 @@ public class UserManagerService extends IUserManager.Stub {
         return mAmInternal;
     }
 
+    /**
+     * Returns true, when user has {@link UserInfo#FLAG_MAIN} and system property
+     * {@link com.android.internal.R.bool.isMainUserPermanentAdmin} is true.
+     */
+    private boolean isNonRemovableMainUser(UserInfo userInfo) {
+        return userInfo.isMain() && isMainUserPermanentAdmin();
+    }
+
+    /**
+     * Returns true, when {@link com.android.internal.R.bool.isMainUserPermanentAdmin} is true.
+     * If the main user is a permanent admin user it can't be deleted
+     * or downgraded to non-admin status.
+     */
+    private static boolean isMainUserPermanentAdmin() {
+        return Resources.getSystem()
+                .getBoolean(com.android.internal.R.bool.config_isMainUserPermanentAdmin);
+    }
+
 }
diff --git a/services/tests/servicestests/src/com/android/server/pm/UserManagerTest.java b/services/tests/servicestests/src/com/android/server/pm/UserManagerTest.java
index 5059ef3d1e3a..4f4980699627 100644
--- a/services/tests/servicestests/src/com/android/server/pm/UserManagerTest.java
+++ b/services/tests/servicestests/src/com/android/server/pm/UserManagerTest.java
@@ -373,6 +373,29 @@ public final class UserManagerTest {
 
     @MediumTest
     @Test
+    public void testRemoveUserWhenPossible_permanentAdminMainUserReturnsError() throws Exception {
+        assumeHeadlessModeEnabled();
+        assumeTrue("Main user is not permanent admin", isMainUserPermanentAdmin());
+
+        int currentUser = ActivityManager.getCurrentUser();
+        final UserInfo otherUser = createUser("User 1", /* flags= */ UserInfo.FLAG_ADMIN);
+        UserHandle mainUser = mUserManager.getMainUser();
+
+        switchUser(otherUser.id, null, true);
+
+        assertThat(mUserManager.removeUserWhenPossible(mainUser,
+                /* overrideDevicePolicy= */ false))
+                .isEqualTo(UserManager.REMOVE_RESULT_ERROR_MAIN_USER_PERMANENT_ADMIN);
+
+
+        assertThat(hasUser(mainUser.getIdentifier())).isTrue();
+
+        // Switch back to the starting user.
+        switchUser(currentUser, null, true);
+    }
+
+    @MediumTest
+    @Test
     public void testRemoveUserWhenPossible_invalidUserReturnsError() throws Exception {
         assertThat(hasUser(Integer.MAX_VALUE)).isFalse();
         assertThat(mUserManager.removeUserWhenPossible(UserHandle.of(Integer.MAX_VALUE),
@@ -1420,4 +1443,10 @@ public final class UserManagerTest {
     private static UserHandle asHandle(int userId) {
         return new UserHandle(userId);
     }
+
+    private boolean isMainUserPermanentAdmin() {
+        return Resources.getSystem()
+                .getBoolean(com.android.internal.R.bool.config_isMainUserPermanentAdmin);
+    }
+
 }