mcs/class/corlib/System.Security/PermissionSet.cs

   1 //
   2 // System.Security.PermissionSet.cs
   3 //
   4 // Authors:
   5 //      Nick Drochak(ndrochak@gol.com)
   6 //      Sebastien Pouliot  <sebastien@ximian.com>
   7 //
   8 // (C) Nick Drochak
   9 // Portions (C) 2003, 2004 Motus Technologies Inc. (http://www.motus.com)
  10 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
  11 //
  12 // Permission is hereby granted, free of charge, to any person obtaining
  13 // a copy of this software and associated documentation files (the
  14 // "Software"), to deal in the Software without restriction, including
  15 // without limitation the rights to use, copy, modify, merge, publish,
  16 // distribute, sublicense, and/or sell copies of the Software, and to
  17 // permit persons to whom the Software is furnished to do so, subject to
  18 // the following conditions:
  19 //
  20 // The above copyright notice and this permission notice shall be
  21 // included in all copies or substantial portions of the Software.
  22 //
  23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  27 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  28 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  29 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  30 //
  31
  32 using System.Collections;
  33 using System.Diagnostics;
  34 using System.IO;
  35 using System.Reflection;
  36 using System.Runtime.InteropServices;
  37 using System.Runtime.Serialization;
  38 using System.Runtime.Serialization.Formatters.Binary;
  39 using System.Security.Permissions;
  40 using System.Security.Policy;
  41 using System.Text;
  42 using System.Threading;
  43
  44 namespace System.Security {
  45
  46         [Serializable]
  47         public class PermissionSet: ISecurityEncodable, ICollection, IEnumerable, IStackWalk, IDeserializationCallback {
  48
  49                 private static string tagName = "PermissionSet";
  50                 private const int version = 1;
  51                 private static object[] psNone = new object [1] { PermissionState.None };
  52
  53                 private PermissionState state;
  54                 private ArrayList list;
  55                 private int _hashcode;
  56                 private PolicyLevel _policyLevel;
  57                 private bool _declsec;
  58
  59                 // constructors
  60
  61                 // for PolicyLevel (to avoid validation duplication)
  62                 internal PermissionSet ()
  63                 {
  64                         list = new ArrayList ();
  65                 }
  66
  67                 public PermissionSet (PermissionState state) : this ()
  68                 {
  69                         if (!Enum.IsDefined (typeof (PermissionState), state))
  70                                 throw new System.ArgumentException ("state");
  71                         this.state = state;
  72                 }
  73
  74                 public PermissionSet (PermissionSet permSet) : this ()
  75                 {
  76                         // LAMESPEC: This would be handled by the compiler.  No way permSet is not a PermissionSet.
  77                         //if (!(permSet is PermissionSet))
  78                         //      throw new System.ArgumentException(); // permSet is not an instance of System.Security.PermissionSet.
  79                         if (permSet == null)
  80                                 state = PermissionState.Unrestricted;
  81                         else {
  82                                 state = permSet.state;
  83                                 foreach (IPermission p in permSet.list)
  84                                         list.Add (p);
  85                         }
  86                 }
  87
  88                 internal PermissionSet (string xml)
  89                         : this ()
  90                 {
  91                         state = PermissionState.None;
  92                         if (xml != null) {
  93                                 SecurityElement se = SecurityElement.FromString (xml);
  94                                 FromXml (se);
  95                         }
  96                 }
  97
  98                 // Light version for creating a (non unrestricted) PermissionSet with
  99                 // a single permission. This allows to relax most validations.
 100                 internal PermissionSet (IPermission perm)
 101                         : this ()
 102                 {
 103                         if (perm != null) {
 104                                 // note: we do not copy IPermission like AddPermission
 105                                 list.Add (perm);
 106                         }
 107                 }
 108
 109                 // methods
 110
 111                 public virtual IPermission AddPermission (IPermission perm)
 112                 {
 113                         if (perm == null)
 114                                 return null;
 115
 116                         // we don't add to an unrestricted permission set unless...
 117                         if (state == PermissionState.Unrestricted) {
 118                                 // we're adding identity permission as they don't support unrestricted
 119                                 if (perm is IUnrestrictedPermission) {
 120                                         // we return the union of the permission with unrestricted
 121                                         // which results in a permission of the same type initialized
 122                                         // with PermissionState.Unrestricted
 123                                         object[] args = new object [1] { PermissionState.Unrestricted };
 124                                         return (IPermission) Activator.CreateInstance (perm.GetType (), args);
 125                                 }
 126                         }
 127
 128                         // we can't add two permissions of the same type in a set
 129                         // so we remove an existing one, union with it and add it back
 130                         IPermission existing = RemovePermission (perm.GetType ());
 131                         if (existing != null) {
 132                                 perm = perm.Union (existing);
 133                         }
 134
 135                         // note: Add doesn't copy
 136                         list.Add (perm);
 137                         return perm;
 138                 }
 139
 140                 [MonoTODO ("Imperative mode isn't supported")]
 141                 public virtual void Assert ()
 142                 {
 143                         new SecurityPermission (SecurityPermissionFlag.Assertion).Demand ();
 144
 145                         int count = this.Count;
 146
 147                         // we (current frame) must have the permission to assert it to others
 148                         // otherwise we don't assert (but we don't throw an exception)
 149                         foreach (IPermission p in list) {
 150                                 // note: we ignore non-CAS permissions
 151                                 if (p is IStackWalk) {
 152                                         if (!SecurityManager.IsGranted (p)) {
 153                                                 return;
 154                                         }
 155                                 } else
 156                                         count--;
 157                         }
 158
 159                         // note: we must ignore the stack modifiers for the non-CAS permissions
 160                         if (SecurityManager.SecurityEnabled && (count > 0))
 161                                 throw new NotSupportedException ("Currently only declarative Assert are supported.");
 162                 }
 163
 164                 internal void Clear ()
 165                 {
 166                         list.Clear ();
 167                 }
 168
 169                 public virtual PermissionSet Copy ()
 170                 {
 171                         return new PermissionSet (this);
 172                 }
 173
 174                 public virtual void CopyTo (Array array, int index)
 175                 {
 176                         if (null == array)
 177                                 throw new ArgumentNullException ("array");
 178
 179                         if (list.Count > 0) {
 180                                 if (array.Rank > 1) {
 181                                         throw new ArgumentException (Locale.GetText (
 182                                                 "Array has more than one dimension"));
 183                                 }
 184                                 if (index < 0 || index >= array.Length) {
 185                                         throw new IndexOutOfRangeException ("index");
 186                                 }
 187
 188                                 list.CopyTo (array, index);
 189                         }
 190                 }
 191
 192                 [MonoTODO ("Imperative Assert, Deny and PermitOnly aren't yet supported")]
 193                 public virtual void Demand ()
 194                 {
 195                         // Note: SecurityEnabled only applies to CAS permissions
 196                         // so we're not checking for it (yet)
 197                         if (IsEmpty ())
 198                                 return;
 199
 200                         PermissionSet cas = this;
 201                         // avoid copy (if possible)
 202                         if (ContainsNonCodeAccessPermissions ()) {
 203                                 // non CAS permissions (e.g. PrincipalPermission) do not requires a stack walk
 204                                 cas = this.Copy ();
 205                                 foreach (IPermission p in list) {
 206                                         Type t = p.GetType ();
 207                                         if (!t.IsSubclassOf (typeof (CodeAccessPermission))) {
 208                                                 p.Demand ();
 209                                                 // we wont have to process this one in the stack walk
 210                                                 cas.RemovePermission (t);
 211                                         }
 212                                 }
 213                         }
 214
 215                         // don't start the stack walk if
 216                         // - the permission set only contains non CAS permissions; or
 217                         // - security isn't enabled (applis only to CAS!)
 218                         if (!cas.IsEmpty () && SecurityManager.SecurityEnabled)
 219                                 CasOnlyDemand (_declsec ? 5 : 3);
 220                 }
 221
 222                 // The number of frames to skip depends on who's calling
 223                 // - CodeAccessPermission.Demand (imperative)
 224                 // - PermissionSet.Demand (imperative)
 225                 // - SecurityManager.InternalDemand (declarative)
 226                 internal void CasOnlyDemand (int skip)
 227                 {
 228                         Assembly current = null;
 229
 230                         // skip ourself, Demand and other security runtime methods
 231                         foreach (SecurityFrame sf in SecurityFrame.GetStack (skip)) {
 232                                 if (ProcessFrame (sf, ref current))
 233                                         return; // reached Assert
 234                         }
 235
 236                         // Is there a CompressedStack to handle ?
 237                         CompressedStack stack = Thread.CurrentThread.GetCompressedStack ();
 238                         if ((stack != null) && !stack.IsEmpty ()) {
 239                                 foreach (SecurityFrame frame in stack.List) {
 240                                         if (ProcessFrame (frame, ref current))
 241                                                 return; // reached Assert
 242                                 }
 243                         }
 244                 }
 245
 246                 [MonoTODO ("Imperative mode isn't supported")]
 247                 public virtual void Deny ()
 248                 {
 249                         if (!SecurityManager.SecurityEnabled)
 250                                 return;
 251
 252                         foreach (IPermission p in list) {
 253                                 // note: we ignore non-CAS permissions
 254                                 if (p is IStackWalk) {
 255                                         throw new NotSupportedException ("Currently only declarative Deny are supported.");
 256                                 }
 257                         }
 258                 }
 259
 260                 [MonoTODO ("adjust class version with current runtime - unification")]
 261                 public virtual void FromXml (SecurityElement et)
 262                 {
 263                         if (et == null)
 264                                 throw new ArgumentNullException ("et");
 265                         if (et.Tag != tagName) {
 266                                 string msg = String.Format ("Invalid tag {0} expected {1}", et.Tag, tagName);
 267                                 throw new ArgumentException (msg, "et");
 268                         }
 269
 270                         if (CodeAccessPermission.IsUnrestricted (et))
 271                                 state = PermissionState.Unrestricted;
 272                         else
 273                                 state = PermissionState.None;
 274
 275                         list.Clear ();
 276                         if (et.Children != null) {
 277                                 foreach (SecurityElement se in et.Children) {
 278                                         string className = se.Attribute ("class");
 279                                         if (className == null) {
 280                                                 throw new ArgumentException (Locale.GetText (
 281                                                         "No permission class is specified."));
 282                                         }
 283                                         if (Resolver != null) {
 284                                                 // policy class names do not have to be fully qualified
 285                                                 className = Resolver.ResolveClassName (className);
 286                                         }
 287                                         // TODO: adjust class version with current runtime (unification)
 288                                         // http://blogs.msdn.com/shawnfa/archive/2004/08/05/209320.aspx
 289                                         Type classType = Type.GetType (className);
 290                                         if (classType != null) {
 291                                                 IPermission p = (IPermission) Activator.CreateInstance (classType, psNone);
 292                                                 p.FromXml (se);
 293                                                 list.Add (p);
 294                                         }
 295 #if !NET_2_0
 296                                         else {
 297                                                 string msg = Locale.GetText ("Can't create an instance of permission class {0}.");
 298                                                 throw new ArgumentException (String.Format (msg, se.Attribute ("class")));
 299                                         }
 300 #endif
 301                                 }
 302                         }
 303                 }
 304
 305                 public virtual IEnumerator GetEnumerator ()
 306                 {
 307                         return list.GetEnumerator ();
 308                 }
 309
 310                 public virtual bool IsSubsetOf (PermissionSet target)
 311                 {
 312                         // if target is empty we must be empty too
 313                         if ((target == null) || (target.IsEmpty ()))
 314                                 return this.IsEmpty ();
 315
 316                         // TODO - non CAS permissions must be evaluated for unrestricted
 317
 318                         // if target is unrestricted then we are a subset
 319                         if (!this.IsUnrestricted () && target.IsUnrestricted ())
 320                                 return true;
 321                         // else target isn't unrestricted.
 322                         // so if we are unrestricted, the we can't be a subset
 323                         if (this.IsUnrestricted () && !target.IsUnrestricted ())
 324                                 return false;
 325
 326                         // if each of our permission is (a) present and (b) a subset of target
 327                         foreach (IPermission p in list) {
 328                                 // for every type in both list
 329                                 IPermission i = target.GetPermission (p.GetType ());
 330                                 if (i == null)
 331                                         return false; // not present (condition a)
 332                                 if (!p.IsSubsetOf (i))
 333                                         return false; // not a subset (condition b)
 334                         }
 335                         return true;
 336                 }
 337
 338                 [MonoTODO ("Imperative mode isn't supported")]
 339                 public virtual void PermitOnly ()
 340                 {
 341                         if (!SecurityManager.SecurityEnabled)
 342                                 return;
 343
 344                         foreach (IPermission p in list) {
 345                                 // note: we ignore non-CAS permissions
 346                                 if (p is IStackWalk) {
 347                                         throw new NotSupportedException ("Currently only declarative Deny are supported.");
 348                                 }
 349                         }
 350                 }
 351
 352                 public bool ContainsNonCodeAccessPermissions ()
 353                 {
 354                         foreach (IPermission p in list) {
 355                                 if (! p.GetType ().IsSubclassOf (typeof (CodeAccessPermission)))
 356                                         return true;
 357                         }
 358                         return false;
 359                 }
 360
 361                 [MonoTODO ("little documentation in Fx 2.0 beta 1")]
 362                 public static byte[] ConvertPermissionSet (string inFormat, byte[] inData, string outFormat)
 363                 {
 364                         if (inFormat == null)
 365                                 throw new ArgumentNullException ("inFormat");
 366                         if (outFormat == null)
 367                                 throw new ArgumentNullException ("outFormat");
 368                         if (inData == null)
 369                                 return null;
 370
 371                         if (inFormat == outFormat)
 372                                 return inData;
 373
 374                         PermissionSet ps = null;
 375
 376                         if (inFormat == "BINARY") {
 377                                 if (outFormat.StartsWith ("XML")) {
 378                                         using (MemoryStream ms = new MemoryStream (inData)) {
 379                                                 BinaryFormatter formatter = new BinaryFormatter ();
 380                                                 ps = (PermissionSet) formatter.Deserialize (ms);
 381                                                 ms.Close ();
 382                                         }
 383                                         string xml = ps.ToString ();
 384                                         switch (outFormat) {
 385                                                 case "XML":
 386                                                 case "XMLASCII":
 387                                                         return Encoding.ASCII.GetBytes (xml);
 388                                                 case "XMLUNICODE":
 389                                                         return Encoding.Unicode.GetBytes (xml);
 390                                         }
 391                                 }
 392                         }
 393                         else if (inFormat.StartsWith ("XML")) {
 394                                 if (outFormat == "BINARY") {
 395                                         string xml = null;
 396                                         switch (inFormat) {
 397                                                 case "XML":
 398                                                 case "XMLASCII":
 399                                                         xml = Encoding.ASCII.GetString (inData);
 400                                                         break;
 401                                                 case "XMLUNICODE":
 402                                                         xml = Encoding.Unicode.GetString (inData);
 403                                                         break;
 404                                         }
 405                                         if (xml != null) {
 406                                                 ps = new PermissionSet (PermissionState.None);
 407                                                 ps.FromXml (SecurityElement.FromString (xml));
 408
 409                                                 MemoryStream ms = new MemoryStream ();
 410                                                 BinaryFormatter formatter = new BinaryFormatter ();
 411                                                 formatter.Serialize (ms, ps);
 412                                                 ms.Close ();
 413                                                 return ms.ToArray ();
 414                                         }
 415                                 }
 416                                 else if (outFormat.StartsWith ("XML")) {
 417                                         string msg = String.Format (Locale.GetText ("Can't convert from {0} to {1}"), inFormat, outFormat);
 418 #if NET_2_0
 419                                         throw new XmlSyntaxException (msg);
 420 #else
 421                                         throw new ArgumentException (msg);
 422 #endif
 423                                 }
 424                         }
 425                         else {
 426                                 // unknown inFormat, returns null
 427                                 return null;
 428                         }
 429                         // unknown outFormat, throw
 430                         throw new SerializationException (String.Format (Locale.GetText ("Unknown output format {0}."), outFormat));
 431                 }
 432
 433                 public virtual IPermission GetPermission (Type permClass)
 434                 {
 435                         foreach (object o in list) {
 436                                 if (o.GetType ().Equals (permClass))
 437                                         return (IPermission) o;
 438                         }
 439                         // it's normal to return null for unrestricted sets
 440                         return null;
 441                 }
 442
 443                 public virtual PermissionSet Intersect (PermissionSet other)
 444                 {
 445                         // no intersection possible
 446                         if ((other == null) || (other.IsEmpty ()) || (this.IsEmpty ()))
 447                                 return null;
 448
 449                         PermissionState state = PermissionState.None;
 450                         if (this.IsUnrestricted () && other.IsUnrestricted ())
 451                                 state = PermissionState.Unrestricted;
 452
 453                         PermissionSet interSet = new PermissionSet (state);
 454                         if (state == PermissionState.Unrestricted) {
 455                                 InternalIntersect (interSet, this, other, true);
 456                                 InternalIntersect (interSet, other, this, true);
 457                         }
 458                         else if (this.IsUnrestricted ()) {
 459                                 InternalIntersect (interSet, this, other, true);
 460                         }
 461                         else if (other.IsUnrestricted ()) {
 462                                 InternalIntersect (interSet, other, this, true);
 463                         }
 464                         else {
 465                                 InternalIntersect (interSet, this, other, false);
 466                         }
 467                         return interSet;
 468                 }
 469
 470                 internal void InternalIntersect (PermissionSet intersect, PermissionSet a, PermissionSet b, bool unrestricted)
 471                 {
 472                         foreach (IPermission p in b.list) {
 473                                 // for every type in both list
 474                                 IPermission i = a.GetPermission (p.GetType ());
 475                                 if (i != null) {
 476                                         // add intersection for this type
 477                                         intersect.AddPermission (p.Intersect (i));
 478                                 }
 479                                 else if (unrestricted && (p is IUnrestrictedPermission)) {
 480                                         intersect.AddPermission (p);
 481                                 }
 482                                 // or reject!
 483                         }
 484                 }
 485
 486                 public virtual bool IsEmpty ()
 487                 {
 488                         // note: Unrestricted isn't empty
 489                         if (state == PermissionState.Unrestricted)
 490                                 return false;
 491                         if ((list == null) || (list.Count == 0))
 492                                 return true;
 493                         // the set may include some empty permissions
 494                         foreach (IPermission p in list) {
 495                                 // empty == fully restricted == IsSubsetOg(null) == true
 496                                 if (!p.IsSubsetOf (null))
 497                                         return false;
 498                         }
 499                         return true;
 500                 }
 501
 502                 public virtual bool IsUnrestricted ()
 503                 {
 504                         return (state == PermissionState.Unrestricted);
 505                 }
 506
 507                 public virtual IPermission RemovePermission (Type permClass)
 508                 {
 509                         if (permClass == null)
 510                                 return null;
 511
 512                         foreach (object o in list) {
 513                                 if (o.GetType ().Equals (permClass)) {
 514                                         list.Remove (o);
 515                                         return (IPermission) o;
 516                                 }
 517                         }
 518                         return null;
 519                 }
 520
 521                 public virtual IPermission SetPermission (IPermission perm)
 522                 {
 523                         if (perm == null)
 524                                 return null;
 525                         if (perm is IUnrestrictedPermission)
 526                                 state = PermissionState.None;
 527                         RemovePermission (perm.GetType ());
 528                         list.Add (perm);
 529                         return perm;
 530                 }
 531
 532                 public override string ToString ()
 533                 {
 534                         return ToXml ().ToString ();
 535                 }
 536
 537                 public virtual SecurityElement ToXml ()
 538                 {
 539                         SecurityElement se = new SecurityElement (tagName);
 540                         se.AddAttribute ("class", GetType ().FullName);
 541                         se.AddAttribute ("version", version.ToString ());
 542                         if (state == PermissionState.Unrestricted)
 543                                 se.AddAttribute ("Unrestricted", "true");
 544
 545                         // required for permissions that do not implement IUnrestrictedPermission
 546                         foreach (IPermission p in list) {
 547                                 se.AddChild (p.ToXml ());
 548                         }
 549                         return se;
 550                 }
 551
 552                 public virtual PermissionSet Union (PermissionSet other)
 553                 {
 554                         if (other == null)
 555                                 return this.Copy ();
 556
 557                         PermissionSet copy = this.Copy ();
 558                         if (this.IsUnrestricted () || other.IsUnrestricted ()) {
 559                                 // so we keep the "right" type
 560                                 copy.Clear ();
 561                                 copy.state = PermissionState.Unrestricted;
 562                                 // copy all permissions that do not implement IUnrestrictedPermission
 563                                 foreach (IPermission p in this.list) {
 564                                         if (!(p is IUnrestrictedPermission))
 565                                                 copy.AddPermission (p);
 566                                 }
 567                                 foreach (IPermission p in other.list) {
 568                                         if (!(p is IUnrestrictedPermission))
 569                                                 copy.AddPermission (p);
 570                                 }
 571                         }
 572                         else {
 573                                 // PermissionState.None -> copy all permissions
 574                                 foreach (IPermission p in other.list) {
 575                                         copy.AddPermission (p);
 576                                 }
 577                         }
 578                         return copy;
 579                 }
 580
 581                 public virtual int Count {
 582                         get { return list.Count; }
 583                 }
 584
 585                 public virtual bool IsSynchronized {
 586                         get { return list.IsSynchronized; }
 587                 }
 588
 589                 public virtual bool IsReadOnly {
 590                         get { return false; } // always false
 591                 }
 592
 593                 public virtual object SyncRoot {
 594                         get { return this; }
 595                 }
 596
 597                 internal bool DeclarativeSecurity {
 598                         get { return _declsec; }
 599                         set { _declsec = value; }
 600                 }
 601
 602                 [MonoTODO()]
 603                 void IDeserializationCallback.OnDeserialization (object sender)
 604                 {
 605                 }
 606
 607 #if NET_2_0
 608                 [ComVisible (false)]
 609                 public override bool Equals (object obj)
 610                 {
 611                         if (obj == null)
 612                                 return false;
 613                         PermissionSet ps = (obj as PermissionSet);
 614                         if (ps == null)
 615                                 return false;
 616                         if (list.Count != ps.Count)
 617                                 return false;
 618
 619                         for (int i=0; i < list.Count; i++) {
 620                                 bool found = false;
 621                                 for (int j=0; i < ps.list.Count; j++) {
 622                                         if (list [i].Equals (ps.list [j])) {
 623                                                 found = true;
 624                                                 break;
 625                                         }
 626                                 }
 627                                 if (!found)
 628                                         return false;
 629                         }
 630                         return true;
 631                 }
 632
 633                 [ComVisible (false)]
 634                 public override int GetHashCode ()
 635                 {
 636                         return (list.Count == 0) ? (int) state : base.GetHashCode ();
 637                 }
 638
 639                 [MonoTODO ("what's it doing here?")]
 640                 static public void RevertAssert ()
 641                 {
 642                         // FIXME: There's probably a reason this was added here ?
 643                         CodeAccessPermission.RevertAssert ();
 644                 }
 645 #endif
 646
 647                 // internal
 648
 649                 internal PolicyLevel Resolver {
 650                         get { return _policyLevel; }
 651                         set { _policyLevel = value; }
 652                 }
 653
 654                 internal bool ProcessFrame (SecurityFrame frame, ref Assembly current)
 655                 {
 656                         if (IsUnrestricted ()) {
 657                                 // we request unrestricted
 658                                 if (frame.Deny != null) {
 659                                         // but have restrictions (some denied permissions)
 660                                         CodeAccessPermission.ThrowSecurityException (this, "Deny", frame.Assembly,
 661                                                 frame.Method, SecurityAction.Demand, null);
 662                                 } else if (frame.PermitOnly != null) {
 663                                         // but have restrictions (onyl some permitted permissions)
 664                                         CodeAccessPermission.ThrowSecurityException (this, "PermitOnly", frame.Assembly,
 665                                                 frame.Method, SecurityAction.Demand, null);
 666                                 }
 667                         }
 668
 669                         foreach (CodeAccessPermission cap in list) {
 670                                 if (cap.ProcessFrame (frame, ref current))
 671                                         return true; // Assert reached - abort stack walk!
 672                         }
 673                         return false;
 674                 }
 675
 676                 // 2.0 metadata format
 677
 678                 internal static PermissionSet CreateFromBinaryFormat (byte[] data)
 679                 {
 680                         if ((data == null) || (data [0] != 0x2E) || (data.Length < 2)) {
 681                                 string msg = Locale.GetText ("Invalid data in 2.0 metadata format.");
 682                                 throw new SecurityException (msg);
 683                         }
 684
 685                         int pos = 1;
 686                         int numattr = ReadEncodedInt (data, ref pos);
 687                         PermissionSet ps = new PermissionSet (PermissionState.None);
 688                         for (int i = 0; i < numattr; i++) {
 689                                 IPermission p = ProcessAttribute (data, ref pos);
 690                                 if (p == null) {
 691                                         string msg = Locale.GetText ("Unsupported data found in 2.0 metadata format.");
 692                                         throw new SecurityException (msg);
 693                                 }
 694                                 ps.AddPermission (p);
 695                         }
 696                         return ps;
 697                 }
 698
 699                 internal static int ReadEncodedInt (byte[] data, ref int position)
 700                 {
 701                         int len = 0;
 702                         if ((data [position] & 0x80) == 0) {
 703                                 len = data [position];
 704                                 position ++;
 705                         } else if ((data [position] & 0x40) == 0) {
 706                                 len = ((data [position] & 0x3f) << 8 | data [position + 1]);
 707                                 position += 2;
 708                         } else {
 709                                 len = (((data [position] & 0x1f) << 24) | (data [position + 1] << 16) |
 710                                         (data [position + 2] << 8) | (data [position + 3]));
 711                                 position += 4;
 712                         }
 713                         return len;
 714                 }
 715
 716                 static object[] action = new object [1] { (SecurityAction) 0 };
 717
 718                 // TODO: add support for arrays and enums
 719                 internal static IPermission ProcessAttribute (byte[] data, ref int position)
 720                 {
 721                         int clen = ReadEncodedInt (data, ref position);
 722                         string cnam = Encoding.UTF8.GetString (data, position, clen);
 723                         position += clen;
 724
 725                         // TODO: Unification
 726                         Type secattr = Type.GetType (cnam);
 727                         SecurityAttribute sa = (Activator.CreateInstance (secattr, action) as SecurityAttribute);
 728                         if (sa == null)
 729                                 return null;
 730
 731                         /*int optionalParametersLength =*/ ReadEncodedInt (data, ref position);
 732                         int numberOfParameters = ReadEncodedInt (data, ref position);
 733                         for (int j=0; j < numberOfParameters; j++) {
 734                                 bool property = false;
 735                                 switch (data [position++]) {
 736                                 case 0x53: // field (technically possible and working)
 737                                         property = false;
 738                                         break;
 739                                 case 0x54: // property (common case)
 740                                         property = true;
 741                                         break;
 742                                 default:
 743                                         return null;
 744                                 }
 745
 746                                 bool array = false;
 747                                 byte type = data [position++];
 748                                 if (type == 0x1D) {
 749                                         array = true;
 750                                         type = data [position++];
 751                                 }
 752
 753                                 int plen = ReadEncodedInt (data, ref position);
 754                                 string pnam = Encoding.UTF8.GetString (data, position, plen);
 755                                 position += plen;
 756
 757                                 int arrayLength = 1;
 758                                 if (array) {
 759                                         arrayLength = BitConverter.ToInt32 (data, position);
 760                                         position += 4;
 761                                 }
 762
 763                                 object obj = null;
 764                                 object[] arrayIndex = null;
 765                                 for (int i = 0; i < arrayLength; i++) {
 766                                         if (array) {
 767                                                 // TODO - setup index
 768                                         }
 769
 770                                         // sadly type values doesn't match ther TypeCode enum :(
 771                                         switch (type) {
 772                                         case 0x02: // MONO_TYPE_BOOLEAN
 773                                                 obj = (object) Convert.ToBoolean (data [position++]);
 774                                                 break;
 775                                         case 0x03: // MONO_TYPE_CHAR
 776                                                 obj = (object) Convert.ToChar (data [position]);
 777                                                 position += 2;
 778                                                 break;
 779                                         case 0x04: // MONO_TYPE_I1
 780                                                 obj = (object) Convert.ToSByte (data [position++]);
 781                                                 break;
 782                                         case 0x05: // MONO_TYPE_U1
 783                                                 obj = (object) Convert.ToByte (data [position++]);
 784                                                 break;
 785                                         case 0x06: // MONO_TYPE_I2
 786                                                 obj = (object) Convert.ToInt16 (data [position]);
 787                                                 position += 2;
 788                                                 break;
 789                                         case 0x07: // MONO_TYPE_U2
 790                                                 obj = (object) Convert.ToUInt16 (data [position]);
 791                                                 position += 2;
 792                                                 break;
 793                                         case 0x08: // MONO_TYPE_I4
 794                                                 obj = (object) Convert.ToInt32 (data [position]);
 795                                                 position += 4;
 796                                                 break;
 797                                         case 0x09: // MONO_TYPE_U4
 798                                                 obj = (object) Convert.ToUInt32 (data [position]);
 799                                                 position += 4;
 800                                                 break;
 801                                         case 0x0A: // MONO_TYPE_I8
 802                                                 obj = (object) Convert.ToInt64 (data [position]);
 803                                                 position += 8;
 804                                                 break;
 805                                         case 0x0B: // MONO_TYPE_U8
 806                                                 obj = (object) Convert.ToUInt64 (data [position]);
 807                                                 position += 8;
 808                                                 break;
 809                                         case 0x0C: // MONO_TYPE_R4
 810                                                 obj = (object) Convert.ToSingle (data [position]);
 811                                                 position += 4;
 812                                                 break;
 813                                         case 0x0D: // MONO_TYPE_R8
 814                                                 obj = (object) Convert.ToDouble (data [position]);
 815                                                 position += 8;
 816                                                 break;
 817                                         case 0x0E: // MONO_TYPE_STRING
 818                                                 string s = null;
 819                                                 if (data [position] != 0xFF) {
 820                                                         int slen = ReadEncodedInt (data, ref position);
 821                                                         s = Encoding.UTF8.GetString (data, position, slen);
 822                                                         position += slen;
 823                                                 } else {
 824                                                         position++;
 825                                                 }
 826                                                 obj = (object) s;
 827                                                 break;
 828                                         case 0x50: // special for TYPE
 829                                                 int tlen = ReadEncodedInt (data, ref position);
 830                                                 obj = (object) Type.GetType (Encoding.UTF8.GetString (data, position, tlen));
 831                                                 position += tlen;
 832                                                 break;
 833                                         default:
 834                                                 return null; // unsupported
 835                                         }
 836
 837                                         if (property) {
 838                                                 PropertyInfo pi = secattr.GetProperty (pnam);
 839                                                 pi.SetValue (sa, obj, arrayIndex);
 840                                         } else {
 841                                                 FieldInfo fi = secattr.GetField (pnam);
 842                                                 fi.SetValue (sa, obj);
 843                                         }
 844                                 }
 845                         }
 846                         return sa.CreatePermission ();
 847                 }
 848         }
 849 }