Lockdown AM.getRunningAppProcesses API with permission.REAL_GET_TASKS

* Applications must now have ...permission.REAL_GET_TASKS to
be able to get process information for all applications.
* Only the process information for the calling application will be
returned if the app doesn't have the permission.
* Privilages apps will temporarily be able to get process information
for all applications if they don't have the new permission, but have
deprecated ...permission.GET_TASKS.

Bug: 20034603
Change-Id: I67ae9491f65d2280adb6a81593693d499714a216
(cherry picked from commit 9dbaa54)

Author: ogunwale

services/core/java/com/android/server/am/ActivityManagerService.java

@@ -8122,7 +8122,7 @@ private boolean isGetTasksAllowed(String caller, int callingPid, int callingUid)
         }
         if (!allowed) {
             Slog.w(TAG, caller + ": caller " + callingUid
-                    + " does not hold GET_TASKS; limiting output");
+                    + " does not hold REAL_GET_TASKS; limiting output");
         }
         return allowed;
     }
@@ -12241,16 +12241,23 @@ private void fillInProcMemInfo(ProcessRecord app,
 
     public List<ActivityManager.RunningAppProcessInfo> getRunningAppProcesses() {
         enforceNotIsolatedCaller("getRunningAppProcesses");
+
+        final int callingUid = Binder.getCallingUid();
+
         // Lazy instantiation of list
         List<ActivityManager.RunningAppProcessInfo> runList = null;
         final boolean allUsers = ActivityManager.checkUidPermission(INTERACT_ACROSS_USERS_FULL,
-                Binder.getCallingUid()) == PackageManager.PERMISSION_GRANTED;
-        int userId = UserHandle.getUserId(Binder.getCallingUid());
+                callingUid) == PackageManager.PERMISSION_GRANTED;
+        final int userId = UserHandle.getUserId(callingUid);
+        final boolean allUids = isGetTasksAllowed(
+                "getRunningAppProcesses", Binder.getCallingPid(), callingUid);
+
         synchronized (this) {
             // Iterate across all processes
-            for (int i=mLruProcesses.size()-1; i>=0; i--) {
+            for (int i = mLruProcesses.size() - 1; i >= 0; i--) {
                 ProcessRecord app = mLruProcesses.get(i);
-                if (!allUsers && app.userId != userId) {
+                if ((!allUsers && app.userId != userId)
+                        || (!allUids && app.uid != callingUid)) {
                     continue;
                 }
                 if ((app.thread != null) && (!app.crashing && !app.notResponding)) {
@@ -12274,7 +12281,7 @@ public List<ActivityManager.RunningAppProcessInfo> getRunningAppProcesses() {
                     //Slog.v(TAG, "Proc " + app.processName + ": imp=" + currApp.importance
                     //        + " lru=" + currApp.lru);
                     if (runList == null) {
-                        runList = new ArrayList<ActivityManager.RunningAppProcessInfo>();
+                        runList = new ArrayList<>();
                     }
                     runList.add(currApp);
                 }