Attempt to improve performance in checksUser

Author: joefarebrother

csharp/ql/lib/semmle/code/csharp/security/auth/InsecureDirectObjectReferenceQuery.qll

@@ -2,6 +2,7 @@
 
 import csharp
 import semmle.code.csharp.dataflow.flowsources.Remote
+import DataFlow as DF
 import TaintTracking as TT
 import ActionMethods
 
@@ -25,20 +26,30 @@ private predicate hasIdParameter(ActionMethod m) {
     exists(StringLiteral idStr, IndexerCall idx |
       idStr.getValue().toLowerCase().matches(["%id", "%idx"]) and
       TT::localTaint(src, DataFlow::exprNode(idx.getQualifier())) and
-      idStr = idx.getArgument(0)
+      DF::localExprFlow(idStr, idx.getArgument(0))
     )
   )
 }
 
+private predicate authorizingCallable(Callable c) {
+  exists(string name | name = c.getName().toLowerCase() |
+    name.matches(["%user%", "%session%"]) and
+    not name.matches("%get%by%") // methods like `getUserById` or `getXByUsername` aren't likely to be referring to the current user
+  )
+}
+
 /** Holds if `m` at some point in its call graph may make some kind of check against the current user. */
 private predicate checksUser(ActionMethod m) {
-  exists(Callable c, string name | name = c.getName().toLowerCase() |
-    name.matches(["%user%", "%session%"]) and
-    not name.matches("%get%by%") and // methods like `getUserById` or `getXByUsername` aren't likely to be referring to the current user
-    m.calls*(c)
+  exists(Callable c |
+    authorizingCallable(c) and
+    callsPlus(m, c)
   )
 }
 
+private predicate calls(Callable c1, Callable c2) { c1.calls(c2) }
+
+private predicate callsPlus(Callable c1, Callable c2) = fastTC(calls/2)(c1, c2)
+
 /** Holds if `m`, its containing class, or a parent class has an attribute that extends `AuthorizeAttribute` */
 private predicate hasAuthorizeAttribute(ActionMethod m) {
   exists(Attribute attr |