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         // Microsoft public key - i.e. only MS signed assembly can inherit from PermissionSet (1.x) or (2.0) FullTrust assemblies
  48         [StrongNameIdentityPermission (SecurityAction.InheritanceDemand, PublicKey="002400000480000094000000060200000024000052534131000400000100010007D1FA57C4AED9F0A32E84AA0FAEFD0DE9E8FD6AEC8F87FB03766C834C99921EB23BE79AD9D5DCC1DD9AD236132102900B723CF980957FC4E177108FC607774F29E8320E92EA05ECE4E821C0A5EFE8F1645C4C0C93C1AB99285D622CAA652C1DFAD63D745D6F2DE5F17E5EAF0FC4963D261C8A12436518206DC093344D5AD293")]
  49         [ComVisible (true)]
  50         [MonoTODO ("CAS support is experimental (and unsupported).")]
  51         public class PermissionSet: ISecurityEncodable, ICollection, IEnumerable, IStackWalk, IDeserializationCallback {
  52
  53                 private const string tagName = "PermissionSet";
  54                 private const int version = 1;
  55                 private static object[] psUnrestricted = new object [1] { PermissionState.Unrestricted };
  56
  57                 private PermissionState state;
  58                 private ArrayList list;
  59                 private PolicyLevel _policyLevel;
  60                 private bool _declsec;
  61                 private bool _readOnly;
  62                 private bool[] _ignored; // for asserts and non-CAS permissions
  63
  64                 // constructors
  65
  66                 // for PolicyLevel (to avoid validation duplication)
  67                 internal PermissionSet ()
  68                 {
  69                         list = new ArrayList ();
  70                 }
  71
  72                 public PermissionSet (PermissionState state) : this ()
  73                 {
  74                         this.state = CodeAccessPermission.CheckPermissionState (state, true);
  75                 }
  76
  77                 public PermissionSet (PermissionSet permSet) : this ()
  78                 {
  79                         // LAMESPEC: This would be handled by the compiler.  No way permSet is not a PermissionSet.
  80                         //if (!(permSet is PermissionSet))
  81                         //      throw new System.ArgumentException(); // permSet is not an instance of System.Security.PermissionSet.
  82                         if (permSet != null) {
  83                                 state = permSet.state;
  84                                 foreach (IPermission p in permSet.list)
  85                                         list.Add (p);
  86                         }
  87                 }
  88
  89                 internal PermissionSet (string xml)
  90                         : this ()
  91                 {
  92                         state = PermissionState.None;
  93                         if (xml != null) {
  94                                 SecurityElement se = SecurityElement.FromString (xml);
  95                                 FromXml (se);
  96                         }
  97                 }
  98
  99                 // Light version for creating a (non unrestricted) PermissionSet with
 100                 // a single permission. This allows to relax most validations.
 101                 internal PermissionSet (IPermission perm)
 102                         : this ()
 103                 {
 104                         if (perm != null) {
 105                                 // note: we do not copy IPermission like AddPermission
 106                                 list.Add (perm);
 107                         }
 108                 }
 109
 110                 // methods
 111
 112                 public IPermission AddPermission (IPermission perm)
 113                 {
 114                         if ((perm == null) || _readOnly)
 115                                 return perm;
 116
 117                         // we don't add to an unrestricted permission set unless...
 118                         if (state == PermissionState.Unrestricted) {
 119                                 // identity permissions can be unrestricted under 2.x
 120                                 {
 121                                         // we return the union of the permission with unrestricted
 122                                         // which results in a permission of the same type initialized
 123                                         // with PermissionState.Unrestricted
 124                                         return (IPermission) Activator.CreateInstance (perm.GetType (), psUnrestricted);
 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 ("CAS support is experimental (and unsupported). Imperative mode is not implemented.")]
 141                 [SecurityPermission (SecurityAction.Demand, Assertion = true)]
 142                 public void Assert ()
 143                 {
 144                         int count = this.Count;
 145
 146                         // we (current frame) must have the permission to assert it to others
 147                         // otherwise we don't assert (but we don't throw an exception)
 148                         foreach (IPermission p in list) {
 149                                 // note: we ignore non-CAS permissions
 150                                 if (p is IStackWalk) {
 151                                         if (!SecurityManager.IsGranted (p)) {
 152                                                 return;
 153                                         }
 154                                 } else
 155                                         count--;
 156                         }
 157
 158                         // note: we must ignore the stack modifiers for the non-CAS permissions
 159                         if (SecurityManager.SecurityEnabled && (count > 0))
 160                                 throw new NotSupportedException ("Currently only declarative Assert are supported.");
 161                 }
 162
 163                 internal void Clear ()
 164                 {
 165                         list.Clear ();
 166                 }
 167
 168                 public virtual PermissionSet Copy ()
 169                 {
 170                         return new PermissionSet (this);
 171                 }
 172
 173                 public virtual void CopyTo (Array array, int index)
 174                 {
 175                         if (null == array)
 176                                 throw new ArgumentNullException ("array");
 177
 178                         if (list.Count > 0) {
 179                                 if (array.Rank > 1) {
 180                                         throw new ArgumentException (Locale.GetText (
 181                                                 "Array has more than one dimension"));
 182                                 }
 183                                 if (index < 0 || index >= array.Length) {
 184                                         throw new IndexOutOfRangeException ("index");
 185                                 }
 186
 187                                 list.CopyTo (array, index);
 188                         }
 189                 }
 190
 191                 public void Demand ()
 192                 {
 193                         // Note: SecurityEnabled only applies to CAS permissions
 194                         // so we're not checking for it (yet)
 195                         if (IsEmpty ())
 196                                 return;
 197
 198                         int n = list.Count;
 199                         if ((_ignored == null) || (_ignored.Length != n)) {
 200                                 _ignored = new bool [n];
 201                         }
 202
 203                         bool call_cas_only = this.IsUnrestricted ();
 204                         // non CAS permissions (e.g. PrincipalPermission) do not requires a stack walk
 205                         for (int i = 0; i < n; i++) {
 206                                 IPermission p = (IPermission) list [i];
 207                                 Type t = p.GetType ();
 208                                 if (t.IsSubclassOf (typeof (CodeAccessPermission))) {
 209                                         _ignored [i] = false;
 210                                         call_cas_only = true;
 211                                 } else {
 212                                         _ignored [i] = true;
 213                                         p.Demand ();
 214                                 }
 215                         }
 216
 217                         // don't start the stack walk if
 218                         // - the permission set only contains non CAS permissions; or
 219                         // - security isn't enabled (applis only to CAS!)
 220                         if (call_cas_only && SecurityManager.SecurityEnabled)
 221                                 CasOnlyDemand (_declsec ? 5 : 3);
 222                 }
 223
 224                 // The number of frames to skip depends on who's calling
 225                 // - CodeAccessPermission.Demand (imperative)
 226                 // - PermissionSet.Demand (imperative)
 227                 // - SecurityManager.InternalDemand (declarative)
 228                 internal void CasOnlyDemand (int skip)
 229                 {
 230 #if !MONO
 231                         Assembly current = null;
 232                         AppDomain domain = null;
 233 #endif
 234
 235                         if (_ignored == null) {
 236                                 // special case when directly called from CodeAccessPermission.Demand
 237                                 _ignored = new bool [list.Count];
 238                         }
 239                 }
 240
 241                 [MonoTODO ("CAS support is experimental (and unsupported). Imperative mode is not implemented.")]
 242                 public void Deny ()
 243                 {
 244                         if (!SecurityManager.SecurityEnabled)
 245                                 return;
 246
 247                         foreach (IPermission p in list) {
 248                                 // note: we ignore non-CAS permissions
 249                                 if (p is IStackWalk) {
 250                                         throw new NotSupportedException ("Currently only declarative Deny are supported.");
 251                                 }
 252                         }
 253                 }
 254
 255                 public virtual void FromXml (SecurityElement et)
 256                 {
 257                         if (et == null)
 258                                 throw new ArgumentNullException ("et");
 259                         if (et.Tag != tagName) {
 260                                 string msg = String.Format ("Invalid tag {0} expected {1}", et.Tag, tagName);
 261                                 throw new ArgumentException (msg, "et");
 262                         }
 263
 264                         list.Clear ();
 265
 266                         if (CodeAccessPermission.IsUnrestricted (et)) {
 267                                 state = PermissionState.Unrestricted;
 268                                 // no need to continue for an unrestricted permission
 269                                 // because identity permissions now "supports" unrestricted
 270                                 return;
 271                         } else {
 272                                 state = PermissionState.None;
 273                         }
 274
 275                         if (et.Children != null) {
 276                                 foreach (SecurityElement se in et.Children) {
 277                                         string className = se.Attribute ("class");
 278                                         if (className == null) {
 279                                                 throw new ArgumentException (Locale.GetText (
 280                                                         "No permission class is specified."));
 281                                         }
 282                                         if (Resolver != null) {
 283                                                 // policy class names do not have to be fully qualified
 284                                                 className = Resolver.ResolveClassName (className);
 285                                         }
 286
 287                                         list.Add (PermissionBuilder.Create (className, se));
 288                                 }
 289                         }
 290                 }
 291
 292                 public IEnumerator GetEnumerator ()
 293                 {
 294                         return list.GetEnumerator ();
 295                 }
 296
 297                 public bool IsSubsetOf (PermissionSet target)
 298                 {
 299                         // if target is empty we must be empty too
 300                         if ((target == null) || (target.IsEmpty ()))
 301                                 return this.IsEmpty ();
 302
 303                         // all permissions support unrestricted in 2.0
 304                         if (target.IsUnrestricted ())
 305                                 return true;
 306                         if (this.IsUnrestricted ())
 307                                 return false;
 308
 309                         if (this.IsUnrestricted () && ((target == null) || !target.IsUnrestricted ()))
 310                                 return false;
 311
 312                         // if each of our permission is (a) present and (b) a subset of target
 313                         foreach (IPermission p in list) {
 314                                 // non CAS permissions must be evaluated for unrestricted
 315                                 Type t = p.GetType ();
 316                                 IPermission i = null;
 317                                 if (target.IsUnrestricted () && (p is CodeAccessPermission) && (p is IUnrestrictedPermission)) {
 318                                         i = (IPermission) Activator.CreateInstance (t, psUnrestricted);
 319                                 } else {
 320                                         i = target.GetPermission (t);
 321                                 }
 322
 323                                 if (!p.IsSubsetOf (i))
 324                                         return false; // not a subset (condition b)
 325                         }
 326                         return true;
 327                 }
 328
 329                 [MonoTODO ("CAS support is experimental (and unsupported). Imperative mode is not implemented.")]
 330                 public void PermitOnly ()
 331                 {
 332                         if (!SecurityManager.SecurityEnabled)
 333                                 return;
 334
 335                         foreach (IPermission p in list) {
 336                                 // note: we ignore non-CAS permissions
 337                                 if (p is IStackWalk) {
 338                                         throw new NotSupportedException ("Currently only declarative Deny are supported.");
 339                                 }
 340                         }
 341                 }
 342
 343                 public bool ContainsNonCodeAccessPermissions ()
 344                 {
 345                         if (list.Count > 0) {
 346                                 foreach (IPermission p in list) {
 347                                         if (! p.GetType ().IsSubclassOf (typeof (CodeAccessPermission)))
 348                                                 return true;
 349                                 }
 350                         }
 351                         return false;
 352                 }
 353
 354                 // FIXME little documentation in Fx 2.0 beta 1
 355                 public static byte[] ConvertPermissionSet (string inFormat, byte[] inData, string outFormat)
 356                 {
 357                         if (inFormat == null)
 358                                 throw new ArgumentNullException ("inFormat");
 359                         if (outFormat == null)
 360                                 throw new ArgumentNullException ("outFormat");
 361                         if (inData == null)
 362                                 return null;
 363
 364                         if (inFormat == outFormat)
 365                                 return inData;
 366
 367                         PermissionSet ps = null;
 368
 369                         if (inFormat == "BINARY") {
 370                                 if (outFormat.StartsWith ("XML")) {
 371                                         using (MemoryStream ms = new MemoryStream (inData)) {
 372                                                 BinaryFormatter formatter = new BinaryFormatter ();
 373                                                 ps = (PermissionSet) formatter.Deserialize (ms);
 374                                                 ms.Close ();
 375                                         }
 376                                         string xml = ps.ToString ();
 377                                         switch (outFormat) {
 378                                                 case "XML":
 379                                                 case "XMLASCII":
 380                                                         return Encoding.ASCII.GetBytes (xml);
 381                                                 case "XMLUNICODE":
 382                                                         return Encoding.Unicode.GetBytes (xml);
 383                                         }
 384                                 }
 385                         }
 386                         else if (inFormat.StartsWith ("XML")) {
 387                                 if (outFormat == "BINARY") {
 388                                         string xml = null;
 389                                         switch (inFormat) {
 390                                                 case "XML":
 391                                                 case "XMLASCII":
 392                                                         xml = Encoding.ASCII.GetString (inData);
 393                                                         break;
 394                                                 case "XMLUNICODE":
 395                                                         xml = Encoding.Unicode.GetString (inData);
 396                                                         break;
 397                                         }
 398                                         if (xml != null) {
 399                                                 ps = new PermissionSet (PermissionState.None);
 400                                                 ps.FromXml (SecurityElement.FromString (xml));
 401
 402                                                 MemoryStream ms = new MemoryStream ();
 403                                                 BinaryFormatter formatter = new BinaryFormatter ();
 404                                                 formatter.Serialize (ms, ps);
 405                                                 ms.Close ();
 406                                                 return ms.ToArray ();
 407                                         }
 408                                 }
 409                                 else if (outFormat.StartsWith ("XML")) {
 410                                         string msg = String.Format (Locale.GetText ("Can't convert from {0} to {1}"), inFormat, outFormat);
 411                                         throw new XmlSyntaxException (msg);
 412                                 }
 413                         }
 414                         else {
 415                                 // unknown inFormat, returns null
 416                                 return null;
 417                         }
 418                         // unknown outFormat, throw
 419                         throw new SerializationException (String.Format (Locale.GetText ("Unknown output format {0}."), outFormat));
 420                 }
 421
 422                 public IPermission GetPermission (Type permClass)
 423                 {
 424                         if ((permClass == null) || (list.Count == 0))
 425                                 return null;
 426
 427                         foreach (object o in list) {
 428                                 if ((o != null) && o.GetType ().Equals (permClass))
 429                                         return (IPermission) o;
 430                         }
 431                         // it's normal to return null for unrestricted sets
 432                         return null;
 433                 }
 434
 435                 public PermissionSet Intersect (PermissionSet other)
 436                 {
 437                         // no intersection possible
 438                         if ((other == null) || (other.IsEmpty ()) || (this.IsEmpty ()))
 439                                 return null;
 440
 441                         PermissionState state = PermissionState.None;
 442                         if (this.IsUnrestricted () && other.IsUnrestricted ())
 443                                 state = PermissionState.Unrestricted;
 444
 445                         PermissionSet interSet = null;
 446                         // much simpler with 2.0
 447                         if (state == PermissionState.Unrestricted) {
 448                                 interSet = new PermissionSet (state);
 449                         } else if (this.IsUnrestricted ()) {
 450                                 interSet = other.Copy ();
 451                         } else if (other.IsUnrestricted ()) {
 452                                 interSet = this.Copy ();
 453                         } else {
 454                                 interSet = new PermissionSet (state);
 455                                 InternalIntersect (interSet, this, other, false);
 456                         }
 457                         return interSet;
 458                 }
 459
 460                 internal void InternalIntersect (PermissionSet intersect, PermissionSet a, PermissionSet b, bool unrestricted)
 461                 {
 462                         foreach (IPermission p in b.list) {
 463                                 // for every type in both list
 464                                 IPermission i = a.GetPermission (p.GetType ());
 465                                 if (i != null) {
 466                                         // add intersection for this type
 467                                         intersect.AddPermission (p.Intersect (i));
 468                                 }
 469                                 // unrestricted is possible for indentity permissions
 470                                 else if (unrestricted) {
 471                                         intersect.AddPermission (p);
 472                                 }
 473                                 // or reject!
 474                         }
 475                 }
 476
 477                 public bool IsEmpty ()
 478                 {
 479                         // note: Unrestricted isn't empty
 480                         if (state == PermissionState.Unrestricted)
 481                                 return false;
 482                         if ((list == null) || (list.Count == 0))
 483                                 return true;
 484                         // the set may include some empty permissions
 485                         foreach (IPermission p in list) {
 486                                 // empty == fully restricted == IsSubsetOf(null) == true
 487                                 if (!p.IsSubsetOf (null))
 488                                         return false;
 489                         }
 490                         return true;
 491                 }
 492
 493                 public bool IsUnrestricted ()
 494                 {
 495                         return (state == PermissionState.Unrestricted);
 496                 }
 497
 498                 public IPermission RemovePermission (Type permClass)
 499                 {
 500                         if ((permClass == null) || _readOnly)
 501                                 return null;
 502
 503                         foreach (object o in list) {
 504                                 if (o.GetType ().Equals (permClass)) {
 505                                         list.Remove (o);
 506                                         return (IPermission) o;
 507                                 }
 508                         }
 509                         return null;
 510                 }
 511
 512                 public IPermission SetPermission (IPermission perm)
 513                 {
 514                         if ((perm == null) || _readOnly)
 515                                 return perm;
 516                         IUnrestrictedPermission u = (perm as IUnrestrictedPermission);
 517                         if (u == null) {
 518                                 state = PermissionState.None;
 519                         } else {
 520                                 state = u.IsUnrestricted () ? state : PermissionState.None;
 521                         }
 522                         RemovePermission (perm.GetType ());
 523                         list.Add (perm);
 524                         return perm;
 525                 }
 526
 527                 public override string ToString ()
 528                 {
 529                         return ToXml ().ToString ();
 530                 }
 531
 532                 public virtual SecurityElement ToXml ()
 533                 {
 534                         SecurityElement se = new SecurityElement (tagName);
 535                         se.AddAttribute ("class", GetType ().FullName);
 536                         se.AddAttribute ("version", version.ToString ());
 537                         if (state == PermissionState.Unrestricted)
 538                                 se.AddAttribute ("Unrestricted", "true");
 539
 540                         // required for permissions that do not implement IUnrestrictedPermission
 541                         foreach (IPermission p in list) {
 542                                 se.AddChild (p.ToXml ());
 543                         }
 544                         return se;
 545                 }
 546
 547                 public PermissionSet Union (PermissionSet other)
 548                 {
 549                         if (other == null)
 550                                 return this.Copy ();
 551
 552                         PermissionSet copy = null;
 553                         if (this.IsUnrestricted () || other.IsUnrestricted ()) {
 554                                 // there are no child elements in unrestricted permission sets
 555                                 return new PermissionSet (PermissionState.Unrestricted);
 556                         } else {
 557                                 copy = this.Copy ();
 558                                 // PermissionState.None -> copy all permissions
 559                                 foreach (IPermission p in other.list) {
 560                                         copy.AddPermission (p);
 561                                 }
 562                         }
 563                         return copy;
 564                 }
 565
 566                 public virtual int Count {
 567                         get { return list.Count; }
 568                 }
 569
 570                 public virtual bool IsSynchronized {
 571                         get { return list.IsSynchronized; }
 572                 }
 573
 574                 public virtual bool IsReadOnly {
 575                         // always false (as documented) but the PermissionSet can be read-only
 576                         // e.g. in a PolicyStatement
 577                         get { return false; }
 578                 }
 579
 580                 public virtual object SyncRoot {
 581                         get { return this; }
 582                 }
 583
 584                 internal bool DeclarativeSecurity {
 585                         get { return _declsec; }
 586                         set { _declsec = value; }
 587                 }
 588
 589                 [MonoTODO ("may not be required")]
 590                 void IDeserializationCallback.OnDeserialization (object sender)
 591                 {
 592                 }
 593
 594                 [ComVisible (false)]
 595                 public override bool Equals (object obj)
 596                 {
 597                         if (obj == null)
 598                                 return false;
 599                         PermissionSet ps = (obj as PermissionSet);
 600                         if (ps == null)
 601                                 return false;
 602                         if (state != ps.state)
 603                                 return false;
 604                         if (list.Count != ps.Count)
 605                                 return false;
 606
 607                         for (int i=0; i < list.Count; i++) {
 608                                 bool found = false;
 609                                 for (int j=0; i < ps.list.Count; j++) {
 610                                         if (list [i].Equals (ps.list [j])) {
 611                                                 found = true;
 612                                                 break;
 613                                         }
 614                                 }
 615                                 if (!found)
 616                                         return false;
 617                         }
 618                         return true;
 619                 }
 620
 621                 [ComVisible (false)]
 622                 public override int GetHashCode ()
 623                 {
 624                         return (list.Count == 0) ? (int) state : base.GetHashCode ();
 625                 }
 626
 627                 // FIXME what's it doing here? There's probably a reason this was added here.
 628                 static public void RevertAssert ()
 629                 {
 630                         CodeAccessPermission.RevertAssert ();
 631                 }
 632
 633                 // internal
 634
 635                 internal PolicyLevel Resolver {
 636                         get { return _policyLevel; }
 637                         set { _policyLevel = value; }
 638                 }
 639
 640                 internal void SetReadOnly (bool value)
 641                 {
 642                         _readOnly = value;
 643                 }
 644
 645                 private bool AllIgnored ()
 646                 {
 647                         if (_ignored == null)
 648                                 throw new NotSupportedException ("bad bad bad");
 649
 650                         for (int i=0; i < _ignored.Length; i++) {
 651                                 if (!_ignored [i])
 652                                         return false;
 653                         }
 654                         // everything is ignored (i.e. non-CAS permission or asserted permission).
 655                         return true;
 656                 }
 657
 658                 // 2.0 metadata format
 659
 660                 internal static PermissionSet CreateFromBinaryFormat (byte[] data)
 661                 {
 662                         if ((data == null) || (data [0] != 0x2E) || (data.Length < 2)) {
 663                                 string msg = Locale.GetText ("Invalid data in 2.0 metadata format.");
 664                                 throw new SecurityException (msg);
 665                         }
 666
 667                         int pos = 1;
 668                         int numattr = ReadEncodedInt (data, ref pos);
 669                         PermissionSet ps = new PermissionSet (PermissionState.None);
 670                         for (int i = 0; i < numattr; i++) {
 671                                 IPermission p = ProcessAttribute (data, ref pos);
 672                                 if (p == null) {
 673                                         string msg = Locale.GetText ("Unsupported data found in 2.0 metadata format.");
 674                                         throw new SecurityException (msg);
 675                                 }
 676                                 ps.AddPermission (p);
 677                         }
 678                         return ps;
 679                 }
 680
 681                 internal static int ReadEncodedInt (byte[] data, ref int position)
 682                 {
 683                         int len = 0;
 684                         if ((data [position] & 0x80) == 0) {
 685                                 len = data [position];
 686                                 position ++;
 687                         } else if ((data [position] & 0x40) == 0) {
 688                                 len = ((data [position] & 0x3f) << 8 | data [position + 1]);
 689                                 position += 2;
 690                         } else {
 691                                 len = (((data [position] & 0x1f) << 24) | (data [position + 1] << 16) |
 692                                         (data [position + 2] << 8) | (data [position + 3]));
 693                                 position += 4;
 694                         }
 695                         return len;
 696                 }
 697
 698                 static object[] action = new object [1] { (SecurityAction) 0 };
 699
 700                 // TODO: add support for arrays and enums (2.0)
 701                 internal static IPermission ProcessAttribute (byte[] data, ref int position)
 702                 {
 703                         int clen = ReadEncodedInt (data, ref position);
 704                         string cnam = Encoding.UTF8.GetString (data, position, clen);
 705                         position += clen;
 706
 707                         Type secattr = Type.GetType (cnam);
 708                         SecurityAttribute sa = (Activator.CreateInstance (secattr, action) as SecurityAttribute);
 709                         if (sa == null)
 710                                 return null;
 711
 712                         /*int optionalParametersLength =*/ ReadEncodedInt (data, ref position);
 713                         int numberOfParameters = ReadEncodedInt (data, ref position);
 714                         for (int j=0; j < numberOfParameters; j++) {
 715                                 bool property = false;
 716                                 switch (data [position++]) {
 717                                 case 0x53: // field (technically possible and working)
 718                                         property = false;
 719                                         break;
 720                                 case 0x54: // property (common case)
 721                                         property = true;
 722                                         break;
 723                                 default:
 724                                         return null;
 725                                 }
 726
 727                                 bool array = false;
 728                                 byte type = data [position++];
 729                                 if (type == 0x1D) {
 730                                         array = true;
 731                                         type = data [position++];
 732                                 }
 733
 734                                 int plen = ReadEncodedInt (data, ref position);
 735                                 string pnam = Encoding.UTF8.GetString (data, position, plen);
 736                                 position += plen;
 737
 738                                 int arrayLength = 1;
 739                                 if (array) {
 740                                         arrayLength = BitConverter.ToInt32 (data, position);
 741                                         position += 4;
 742                                 }
 743
 744                                 object obj = null;
 745                                 object[] arrayIndex = null;
 746                                 for (int i = 0; i < arrayLength; i++) {
 747                                         if (array) {
 748                                                 // TODO - setup index (2.0)
 749                                         }
 750
 751                                         // sadly type values doesn't match ther TypeCode enum :(
 752                                         switch (type) {
 753                                         case 0x02: // MONO_TYPE_BOOLEAN
 754                                                 obj = (object) Convert.ToBoolean (data [position++]);
 755                                                 break;
 756                                         case 0x03: // MONO_TYPE_CHAR
 757                                                 obj = (object) Convert.ToChar (data [position]);
 758                                                 position += 2;
 759                                                 break;
 760                                         case 0x04: // MONO_TYPE_I1
 761                                                 obj = (object) Convert.ToSByte (data [position++]);
 762                                                 break;
 763                                         case 0x05: // MONO_TYPE_U1
 764                                                 obj = (object) Convert.ToByte (data [position++]);
 765                                                 break;
 766                                         case 0x06: // MONO_TYPE_I2
 767                                                 obj = (object) Convert.ToInt16 (data [position]);
 768                                                 position += 2;
 769                                                 break;
 770                                         case 0x07: // MONO_TYPE_U2
 771                                                 obj = (object) Convert.ToUInt16 (data [position]);
 772                                                 position += 2;
 773                                                 break;
 774                                         case 0x08: // MONO_TYPE_I4
 775                                                 obj = (object) Convert.ToInt32 (data [position]);
 776                                                 position += 4;
 777                                                 break;
 778                                         case 0x09: // MONO_TYPE_U4
 779                                                 obj = (object) Convert.ToUInt32 (data [position]);
 780                                                 position += 4;
 781                                                 break;
 782                                         case 0x0A: // MONO_TYPE_I8
 783                                                 obj = (object) Convert.ToInt64 (data [position]);
 784                                                 position += 8;
 785                                                 break;
 786                                         case 0x0B: // MONO_TYPE_U8
 787                                                 obj = (object) Convert.ToUInt64 (data [position]);
 788                                                 position += 8;
 789                                                 break;
 790                                         case 0x0C: // MONO_TYPE_R4
 791                                                 obj = (object) Convert.ToSingle (data [position]);
 792                                                 position += 4;
 793                                                 break;
 794                                         case 0x0D: // MONO_TYPE_R8
 795                                                 obj = (object) Convert.ToDouble (data [position]);
 796                                                 position += 8;
 797                                                 break;
 798                                         case 0x0E: // MONO_TYPE_STRING
 799                                                 string s = null;
 800                                                 if (data [position] != 0xFF) {
 801                                                         int slen = ReadEncodedInt (data, ref position);
 802                                                         s = Encoding.UTF8.GetString (data, position, slen);
 803                                                         position += slen;
 804                                                 } else {
 805                                                         position++;
 806                                                 }
 807                                                 obj = (object) s;
 808                                                 break;
 809                                         case 0x50: // special for TYPE
 810                                                 int tlen = ReadEncodedInt (data, ref position);
 811                                                 obj = (object) Type.GetType (Encoding.UTF8.GetString (data, position, tlen));
 812                                                 position += tlen;
 813                                                 break;
 814                                         default:
 815                                                 return null; // unsupported
 816                                         }
 817
 818                                         if (property) {
 819                                                 PropertyInfo pi = secattr.GetProperty (pnam);
 820                                                 pi.SetValue (sa, obj, arrayIndex);
 821                                         } else {
 822                                                 FieldInfo fi = secattr.GetField (pnam);
 823                                                 fi.SetValue (sa, obj);
 824                                         }
 825                                 }
 826                         }
 827                         return sa.CreatePermission ();
 828                 }
 829         }
 830 }