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|
(* Copyright (c) 2010, Adam Chlipala
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - The names of contributors may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*)
structure Iflow :> IFLOW = struct
open Mono
structure IM = IntBinaryMap
structure SS = BinarySetFn(struct
type ord_key = string
val compare = String.compare
end)
val writers = ["htmlifyInt_w",
"htmlifyFloat_w",
"htmlifyString_w",
"htmlifyBool_w",
"htmlifyTime_w",
"attrifyInt_w",
"attrifyFloat_w",
"attrifyString_w",
"attrifyChar_w",
"urlifyInt_w",
"urlifyFloat_w",
"urlifyString_w",
"urlifyBool_w"]
val writers = SS.addList (SS.empty, writers)
type lvar = int
datatype exp =
Const of Prim.t
| Var of int
| Lvar of lvar
| Func of string * exp list
| Recd of (string * exp) list
| Proj of exp * string
| Finish
datatype reln =
Sql of string
| Eq
datatype prop =
True
| False
| Unknown
| And of prop * prop
| Or of prop * prop
| Reln of reln * exp list
| Select of int * lvar * lvar * prop * exp
local
val count = ref 1
in
fun newLvar () =
let
val n = !count
in
count := n + 1;
n
end
end
fun subExp (v, lv) =
let
fun sub e =
case e of
Const _ => e
| Var v' => if v' = v then Lvar lv else e
| Lvar _ => e
| Func (f, es) => Func (f, map sub es)
| Recd xes => Recd (map (fn (x, e) => (x, sub e)) xes)
| Proj (e, s) => Proj (sub e, s)
| Finish => Finish
in
sub
end
fun subProp (v, lv) =
let
fun sub p =
case p of
True => p
| False => p
| Unknown => p
| And (p1, p2) => And (sub p1, sub p2)
| Or (p1, p2) => Or (sub p1, sub p2)
| Reln (r, es) => Reln (r, map (subExp (v, lv)) es)
| Select (v1, lv1, lv2, p, e) => Select (v1, lv1, lv2, sub p, subExp (v, lv) e)
in
sub
end
fun isKnown e =
case e of
Const _ => true
| Func (_, es) => List.all isKnown es
| Recd xes => List.all (isKnown o #2) xes
| Proj (e, _) => isKnown e
| _ => false
fun isFinish e =
case e of
Finish => true
| _ => false
fun simplify e =
case e of
Const _ => e
| Var _ => e
| Lvar _ => e
| Func (f, es) =>
let
val es = map simplify es
in
if List.exists isFinish es then
Finish
else
Func (f, es)
end
| Recd xes =>
let
val xes = map (fn (x, e) => (x, simplify e)) xes
in
if List.exists (isFinish o #2) xes then
Finish
else
Recd xes
end
| Proj (e, s) =>
(case simplify e of
Recd xes =>
getOpt (ListUtil.search (fn (x, e') => if x = s then SOME e' else NONE) xes, Recd xes)
| e' =>
if isFinish e' then
Finish
else
Proj (e', s))
| Finish => Finish
fun decomp fals or =
let
fun decomp p k =
case p of
True => k []
| False => fals
| Unknown => k []
| And (p1, p2) =>
decomp p1 (fn ps1 =>
decomp p2 (fn ps2 =>
k (ps1 @ ps2)))
| Or (p1, p2) =>
or (decomp p1 k, fn () => decomp p2 k)
| Reln x => k [x]
| Select _ => k []
in
decomp
end
val unif = ref (IM.empty : exp IM.map)
fun reset () = unif := IM.empty
fun save () = !unif
fun restore x = unif := x
fun lvarIn lv =
let
fun lvi e =
case e of
Const _ => false
| Var _ => false
| Lvar lv' => lv' = lv
| Func (_, es) => List.exists lvi es
| Recd xes => List.exists (lvi o #2) xes
| Proj (e, _) => lvi e
| Finish => false
in
lvi
end
fun eq' (e1, e2) =
case (e1, e2) of
(Const p1, Const p2) => Prim.equal (p1, p2)
| (Var n1, Var n2) => n1 = n2
| (Lvar n1, _) =>
(case IM.find (!unif, n1) of
SOME e1 => eq' (e1, e2)
| NONE =>
case e2 of
Lvar n2 =>
(case IM.find (!unif, n2) of
SOME e2 => eq' (e1, e2)
| NONE => n1 = n2
orelse (unif := IM.insert (!unif, n1, e2);
true))
| _ =>
if lvarIn n1 e2 then
false
else
(unif := IM.insert (!unif, n1, e2);
true))
| (_, Lvar n2) =>
(case IM.find (!unif, n2) of
SOME e2 => eq' (e1, e2)
| NONE =>
if lvarIn n2 e1 then
false
else
(unif := IM.insert (!unif, n2, e1);
true))
| (Func (f1, es1), Func (f2, es2)) => f1 = f2 andalso ListPair.allEq eq' (es1, es2)
| (Recd xes1, Recd xes2) => ListPair.allEq (fn ((x1, e1), (x2, e2)) => x1 = x2 andalso eq' (e1, e2)) (xes1, xes2)
| (Proj (e1, s1), Proj (e2, s2)) => eq' (e1, e2) andalso s1 = s2
| (Finish, Finish) => true
| _ => false
fun eq (e1, e2) =
let
val saved = save ()
in
if eq' (simplify e1, simplify e2) then
true
else
(restore saved;
false)
end
exception Imply of prop * prop
fun rimp ((r1, es1), (r2, es2)) =
case (r1, r2) of
(Sql r1', Sql r2') =>
r1' = r2' andalso
(case (es1, es2) of
([Recd xes1], [Recd xes2]) =>
let
val saved = save ()
in
if List.all (fn (f, e2) =>
case ListUtil.search (fn (f', e1) => if f' = f then SOME e1 else NONE) xes1 of
NONE => true
| SOME e1 => eq (e1, e2)) xes2 then
true
else
(restore saved;
false)
end
| _ => false)
| (Eq, Eq) =>
(case (es1, es2) of
([x1, y1], [x2, y2]) =>
let
val saved = save ()
in
if eq (x1, x2) andalso eq (y1, y2) then
true
else
(restore saved;
(*raise Imply (Reln (Eq, es1), Reln (Eq, es2));*)
eq (x1, y2) andalso eq (y1, x2))
end
| _ => false)
| _ => false
fun imply (p1, p2) =
(reset ();
(*raise (Imply (p1, p2));*)
decomp true (fn (e1, e2) => e1 andalso e2 ()) p1
(fn hyps =>
decomp false (fn (e1, e2) => e1 orelse e2 ()) p2
(fn goals =>
let
fun gls goals onFail =
case goals of
[] => true
| g :: goals =>
let
fun hps hyps =
case hyps of
[] => onFail ()
| h :: hyps =>
let
val saved = save ()
in
if rimp (h, g) then
let
val changed = IM.numItems (!unif) <> IM.numItems saved
in
gls goals (fn () => (restore saved;
changed andalso hps hyps))
end
else
hps hyps
end
in
hps hyps
end
in
gls goals (fn () => false)
end)))
fun patCon pc =
case pc of
PConVar n => "C" ^ Int.toString n
| PConFfi {mod = m, datatyp = d, con = c, ...} => m ^ "." ^ d ^ "." ^ c
datatype chunk =
String of string
| Exp of Mono.exp
fun chunkify e =
case #1 e of
EPrim (Prim.String s) => [String s]
| EStrcat (e1, e2) => chunkify e1 @ chunkify e2
| _ => [Exp e]
type 'a parser = chunk list -> ('a * chunk list) option
fun always v chs = SOME (v, chs)
fun parse p s =
case p (chunkify s) of
SOME (v, []) => SOME v
| _ => NONE
fun const s chs =
case chs of
String s' :: chs => if String.isPrefix s s' then
SOME ((), if size s = size s' then
chs
else
String (String.extract (s', size s, NONE)) :: chs)
else
NONE
| _ => NONE
fun follow p1 p2 chs =
case p1 chs of
NONE => NONE
| SOME (v1, chs) =>
case p2 chs of
NONE => NONE
| SOME (v2, chs) => SOME ((v1, v2), chs)
fun wrap p f chs =
case p chs of
NONE => NONE
| SOME (v, chs) => SOME (f v, chs)
fun alt p1 p2 chs =
case p1 chs of
NONE => p2 chs
| v => v
fun skip cp chs =
case chs of
String "" :: chs => skip cp chs
| String s :: chs' => if cp (String.sub (s, 0)) then
skip cp (String (String.extract (s, 1, NONE)) :: chs')
else
SOME ((), chs)
| _ => SOME ((), chs)
fun keep cp chs =
case chs of
String "" :: chs => keep cp chs
| String s :: chs' =>
let
val (befor, after) = Substring.splitl cp (Substring.full s)
in
if Substring.isEmpty befor then
NONE
else
SOME (Substring.string befor,
if Substring.isEmpty after then
chs'
else
String (Substring.string after) :: chs')
end
| _ => NONE
fun ws p = wrap (follow p (skip (fn ch => ch = #" "))) #1
fun list p chs =
(alt (wrap (follow p (follow (ws (const ",")) (list p)))
(fn (v, ((), ls)) => v :: ls))
(alt (wrap (ws p) (fn v => [v]))
(always []))) chs
val ident = keep (fn ch => Char.isAlphaNum ch orelse ch = #"_")
val t_ident = wrap ident (fn s => if String.isPrefix "T_" s then
String.extract (s, 2, NONE)
else
raise Fail "Iflow: Bad table variable")
val uw_ident = wrap ident (fn s => if String.isPrefix "uw_" s then
String.extract (s, 3, NONE)
else
raise Fail "Iflow: Bad uw_* variable")
val sitem = wrap (follow t_ident
(follow (const ".")
uw_ident))
(fn (t, ((), f)) => (t, f))
val select = wrap (follow (const "SELECT ") (list sitem))
(fn ((), ls) => ls)
val fitem = wrap (follow uw_ident
(follow (const " AS ")
t_ident))
(fn (t, ((), f)) => (t, f))
val from = wrap (follow (const "FROM ") (list fitem))
(fn ((), ls) => ls)
val query = wrap (follow select from)
(fn (fs, ts) => {Select = fs, From = ts})
fun queryProp rv oe e =
case parse query e of
NONE => Unknown
| SOME r =>
let
val p =
foldl (fn ((t, v), p) =>
And (p,
Reln (Sql t,
[Recd (foldl (fn ((v', f), fs) =>
if v' = v then
(f, Proj (Proj (Lvar rv, v), f)) :: fs
else
fs) [] (#Select r))])))
True (#From r)
in
case oe of
NONE => p
| SOME oe =>
And (p,
foldl (fn ((v, f), p) =>
Or (p,
Reln (Eq, [oe, Proj (Proj (Lvar rv, v), f)])))
False (#Select r))
end
fun evalExp env (e as (_, loc), st as (nv, p, sent)) =
let
fun default () =
(Var nv, (nv+1, p, sent))
fun addSent (p, e, sent) =
if isKnown e then
sent
else
(loc, e, p) :: sent
in
case #1 e of
EPrim p => (Const p, st)
| ERel n => (List.nth (env, n), st)
| ENamed _ => default ()
| ECon (_, pc, NONE) => (Func (patCon pc, []), st)
| ECon (_, pc, SOME e) =>
let
val (e, st) = evalExp env (e, st)
in
(Func (patCon pc, [e]), st)
end
| ENone _ => (Func ("None", []), st)
| ESome (_, e) =>
let
val (e, st) = evalExp env (e, st)
in
(Func ("Some", [e]), st)
end
| EFfi _ => default ()
| EFfiApp (m, s, es) =>
if m = "Basis" andalso SS.member (writers, s) then
let
val (es, st) = ListUtil.foldlMap (evalExp env) st es
in
(Func ("unit", []), (#1 st, p, foldl (fn (e, sent) => addSent (#2 st, e, sent)) sent es))
end
else if Settings.isEffectful (m, s) andalso not (Settings.isBenignEffectful (m, s)) then
default ()
else
let
val (es, st) = ListUtil.foldlMap (evalExp env) st es
in
(Func (m ^ "." ^ s, es), st)
end
| EApp _ => default ()
| EAbs _ => default ()
| EUnop (s, e1) =>
let
val (e1, st) = evalExp env (e1, st)
in
(Func (s, [e1]), st)
end
| EBinop (s, e1, e2) =>
let
val (e1, st) = evalExp env (e1, st)
val (e2, st) = evalExp env (e2, st)
in
(Func (s, [e1, e2]), st)
end
| ERecord xets =>
let
val (xes, st) = ListUtil.foldlMap (fn ((x, e, _), st) =>
let
val (e, st) = evalExp env (e, st)
in
((x, e), st)
end) st xets
in
(Recd xes, st)
end
| EField (e, s) =>
let
val (e, st) = evalExp env (e, st)
in
(Proj (e, s), st)
end
| ECase _ => default ()
| EStrcat (e1, e2) =>
let
val (e1, st) = evalExp env (e1, st)
val (e2, st) = evalExp env (e2, st)
in
(Func ("cat", [e1, e2]), st)
end
| EError _ => (Finish, st)
| EReturnBlob {blob = b, mimeType = m, ...} =>
let
val (b, st) = evalExp env (b, st)
val (m, st) = evalExp env (m, st)
in
(Finish, (#1 st, p, addSent (#2 st, b, addSent (#2 st, m, sent))))
end
| ERedirect (e, _) =>
let
val (e, st) = evalExp env (e, st)
in
(Finish, (#1 st, p, addSent (#2 st, e, sent)))
end
| EWrite e =>
let
val (e, st) = evalExp env (e, st)
in
(Func ("unit", []), (#1 st, p, addSent (#2 st, e, sent)))
end
| ESeq (e1, e2) =>
let
val (_, st) = evalExp env (e1, st)
in
evalExp env (e2, st)
end
| ELet (_, _, e1, e2) =>
let
val (e1, st) = evalExp env (e1, st)
in
evalExp (e1 :: env) (e2, st)
end
| EClosure (n, es) =>
let
val (es, st) = ListUtil.foldlMap (evalExp env) st es
in
(Func ("Cl" ^ Int.toString n, es), st)
end
| EQuery {query = q, body = b, initial = i, ...} =>
let
val (_, st) = evalExp env (q, st)
val (i, st) = evalExp env (i, st)
val r = #1 st
val acc = #1 st + 1
val st' = (#1 st + 2, #2 st, #3 st)
val (b, st') = evalExp (Var acc :: Var r :: env) (b, st')
val r' = newLvar ()
val acc' = newLvar ()
val qp = queryProp r' NONE q
val doSubExp = subExp (r, r') o subExp (acc, acc')
val doSubProp = subProp (r, r') o subProp (acc, acc')
val p = doSubProp (#2 st')
val p = And (p, qp)
val p = Select (r, r', acc', p, doSubExp b)
in
(Var r, (#1 st + 1, And (#2 st, p), map (fn (loc, e, p) => (loc,
doSubExp e,
And (qp, doSubProp p))) (#3 st')))
end
| EDml _ => default ()
| ENextval _ => default ()
| ESetval _ => default ()
| EUnurlify _ => default ()
| EJavaScript _ => default ()
| ESignalReturn _ => default ()
| ESignalBind _ => default ()
| ESignalSource _ => default ()
| EServerCall _ => default ()
| ERecv _ => default ()
| ESleep _ => default ()
| ESpawn _ => default ()
end
fun check file =
let
fun decl ((d, _), (vals, pols)) =
case d of
DVal (x, _, _, e, _) =>
let
fun deAbs (e, env, nv) =
case #1 e of
EAbs (_, _, _, e) => deAbs (e, Var nv :: env, nv + 1)
| _ => (e, env, nv)
val (e, env, nv) = deAbs (e, [], 1)
val (e, (_, p, sent)) = evalExp env (e, (nv, True, []))
in
((x, e, p, sent) :: vals, pols)
end
| DPolicy (PolQuery e) => (vals, queryProp 0 (SOME (Var 0)) e :: pols)
| _ => (vals, pols)
val () = reset ()
val (vals, pols) = foldl decl ([], []) file
in
app (fn (name, _, _, sent) =>
app (fn (loc, e, p) =>
let
val p = And (p, Reln (Eq, [Var 0, e]))
in
if List.exists (fn pol => imply (p, pol)) pols then
()
else
ErrorMsg.errorAt loc "The information flow policy may be violated here."
end) sent) vals
end
end
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