simplehistoryinspect.aml

(* doPrivileged : (unit -> a) -> a *)
(* passed a function f that is run on unit--used in the stack inspection mechanism *)
fun doPrivileged f =
      f ()

val history:Ref List (String,String) = ref Nil

advice before (any) (arg,st,fi) = 
	      ((history := ((getFileName fi, getFunName fi)::(!history))); arg)

(* a real implementation of history-based inspection would require 
 me to define intersectPerm functions for all the permissions
  this will do for now *)
fun checkHistory (history : List (String,String), 
		  p : (String,List Arg)):Bool =
    case history of
	((filename,funname)::t1) => 
	let val _ = print (filename ^ " : ^ " ^ funname ^ " || ") in 
	if equals (funname, "doPrivileged")
	then (case t1 of
		  ((filename2,funname2)::t2) => 
		  impliesPermissions (getPermissions (filename2, 
						      policyfile), 
				      p)
		| Nil => False (* Shouldn't happen *))
	else impliesPermissions (getPermissions (filename, 
						 policyfile),
				 p)
             andalso checkHistory (t1, p) end
      | Nil => True
	 
(* I didn't want to have to rewrite filesecurity.aml and netsecurity.aml *)
(* if this file is used, calls to stack inspection are overridden by the history inspection mechanism *)
fun checkStack (st, 
		p : (String,List Arg)) : Bool =
    case !history of
	(* must take checkStack and checkRead off the history *)
	(_::_::hist) => checkHistory(hist, p)