From c354b1948a9311a007b213e30dc9e6ef4c5f46bf Mon Sep 17 00:00:00 2001
From: Yohei Yukawa <yukawa@google.com>
Date: Fri, 29 Jul 2022 06:37:26 +0900
Subject: [PATCH] Remove IMMS#calledFromValidUserLocked() as it's unused

This CL finally removes

  InputMethodManagerService#calledFromValidUserLocked(),

as it is no longer used.

This method was originally introduced for a minimum multi-user support
for IMMS [1][2].  The motivation was to allow SystemUI (this includes
the lock screen) and some special processes that always run user 0 to
call at least the following IPCs defined in IInputMethodManager.

 * addClient()
 * removeClient()
 * startInput()
 * windowGainedFocus()
 * showSoftInput()
 * hideSoftInput()
 * showInputMethodPickerFromClient()

As a result, we added the following allow-rules as a quick workaround.

 * callingUid == Process.SYSTEM_UID
 * INTERACT_ACROSS_USERS_FULL

The problem was that IMMS#calledFromValidUserLocked() had been called
not from those IPC entry points but also from other IPC entry points,
and it became really difficult to understand what IPCs must have had
such allow-rules, and what IPCs must have not.  This is basically why
we started an effort to deprecate IMMS#calledFromValidUserLocked for
better code readability.

Anyway we have finally finished the audit and migration, and
IMMS#calledFromValidUserLocked() is now ready to be removed.

This CL itself has no behavior change, since the method to be removed
is no longer used.

 [1]: Ib23849d352db33f0747aa9d5a178f00ac726c13b
      4e1ab15b305aac26ad8819fc3b2951e20985944d
 [2]: I1620413578b9e8da6564664219f65bdc00d5ecfd
      135e5fb71242b1151929e2ea7bf221ff421e6ad2

Fix: 34886274
Test: presubmit
Change-Id: I71a310eea393c8705dc0714a9a968647d76c81ac
---
 .../InputMethodManagerService.java            | 43 -------------------
 1 file changed, 43 deletions(-)

diff --git a/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java b/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java
index c165562e49e9a..38ed8a48540a0 100644
--- a/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java
+++ b/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java
@@ -2016,49 +2016,6 @@ public final class InputMethodManagerService extends IInputMethodManager.Stub
         }
     }
 
-    // ---------------------------------------------------------------------------------------
-    // Check whether or not this is a valid IPC. Assumes an IPC is valid when either
-    // 1) it comes from the system process
-    // 2) the calling process' user id is identical to the current user id IMMS thinks.
-    @GuardedBy("ImfLock.class")
-    private boolean calledFromValidUserLocked() {
-        final int uid = Binder.getCallingUid();
-        final int userId = UserHandle.getUserId(uid);
-        if (DEBUG) {
-            Slog.d(TAG, "--- calledFromForegroundUserOrSystemProcess ? "
-                    + "calling uid = " + uid + " system uid = " + Process.SYSTEM_UID
-                    + " calling userId = " + userId + ", foreground user id = "
-                    + mSettings.getCurrentUserId() + ", calling pid = " + Binder.getCallingPid()
-                    + InputMethodUtils.getApiCallStack());
-        }
-        if (uid == Process.SYSTEM_UID) {
-            return true;
-        }
-        if (userId == mSettings.getCurrentUserId()) {
-            return true;
-        }
-
-        // Caveat: A process which has INTERACT_ACROSS_USERS_FULL gets results for the
-        // foreground user, not for the user of that process. Accordingly InputMethodManagerService
-        // must not manage background users' states in any functions.
-        // Note that privacy-sensitive IPCs, such as setInputMethod, are still securely guarded
-        // by a token.
-        if (mContext.checkCallingOrSelfPermission(
-                android.Manifest.permission.INTERACT_ACROSS_USERS_FULL)
-                == PackageManager.PERMISSION_GRANTED) {
-            if (DEBUG) {
-                Slog.d(TAG, "--- Access granted because the calling process has "
-                        + "the INTERACT_ACROSS_USERS_FULL permission");
-            }
-            return true;
-        }
-        // TODO(b/34886274): The semantics of this verification is actually not well-defined.
-        Slog.w(TAG, "--- IPC called from background users. Ignore. callers="
-                + Debug.getCallers(10));
-        return false;
-    }
-
-
     /**
      * Returns true iff the caller is identified to be the current input method with the token.
      * @param token The window token given to the input method when it was started.