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                         Assembly current = null;
 231                         AppDomain domain = null;
 232
 233                         if (_ignored == null) {
 234                                 // special case when directly called from CodeAccessPermission.Demand
 235                                 _ignored = new bool [list.Count];
 236                         }
 237                 }
 238
 239                 [MonoTODO ("CAS support is experimental (and unsupported). Imperative mode is not implemented.")]
 240                 public void Deny ()
 241                 {
 242                         if (!SecurityManager.SecurityEnabled)
 243                                 return;
 244
 245                         foreach (IPermission p in list) {
 246                                 // note: we ignore non-CAS permissions
 247                                 if (p is IStackWalk) {
 248                                         throw new NotSupportedException ("Currently only declarative Deny are supported.");
 249                                 }
 250                         }
 251                 }
 252
 253                 public virtual void FromXml (SecurityElement et)
 254                 {
 255                         if (et == null)
 256                                 throw new ArgumentNullException ("et");
 257                         if (et.Tag != tagName) {
 258                                 string msg = String.Format ("Invalid tag {0} expected {1}", et.Tag, tagName);
 259                                 throw new ArgumentException (msg, "et");
 260                         }
 261
 262                         list.Clear ();
 263
 264                         if (CodeAccessPermission.IsUnrestricted (et)) {
 265                                 state = PermissionState.Unrestricted;
 266                                 // no need to continue for an unrestricted permission
 267                                 // because identity permissions now "supports" unrestricted
 268                                 return;
 269                         } else {
 270                                 state = PermissionState.None;
 271                         }
 272
 273                         if (et.Children != null) {
 274                                 foreach (SecurityElement se in et.Children) {
 275                                         string className = se.Attribute ("class");
 276                                         if (className == null) {
 277                                                 throw new ArgumentException (Locale.GetText (
 278                                                         "No permission class is specified."));
 279                                         }
 280                                         if (Resolver != null) {
 281                                                 // policy class names do not have to be fully qualified
 282                                                 className = Resolver.ResolveClassName (className);
 283                                         }
 284
 285                                         list.Add (PermissionBuilder.Create (className, se));
 286                                 }
 287                         }
 288                 }
 289
 290                 public IEnumerator GetEnumerator ()
 291                 {
 292                         return list.GetEnumerator ();
 293                 }
 294
 295                 public bool IsSubsetOf (PermissionSet target)
 296                 {
 297                         // if target is empty we must be empty too
 298                         if ((target == null) || (target.IsEmpty ()))
 299                                 return this.IsEmpty ();
 300
 301                         // all permissions support unrestricted in 2.0
 302                         if (target.IsUnrestricted ())
 303                                 return true;
 304                         if (this.IsUnrestricted ())
 305                                 return false;
 306
 307                         if (this.IsUnrestricted () && ((target == null) || !target.IsUnrestricted ()))
 308                                 return false;
 309
 310                         // if each of our permission is (a) present and (b) a subset of target
 311                         foreach (IPermission p in list) {
 312                                 // non CAS permissions must be evaluated for unrestricted
 313                                 Type t = p.GetType ();
 314                                 IPermission i = null;
 315                                 if (target.IsUnrestricted () && (p is CodeAccessPermission) && (p is IUnrestrictedPermission)) {
 316                                         i = (IPermission) Activator.CreateInstance (t, psUnrestricted);
 317                                 } else {
 318                                         i = target.GetPermission (t);
 319                                 }
 320
 321                                 if (!p.IsSubsetOf (i))
 322                                         return false; // not a subset (condition b)
 323                         }
 324                         return true;
 325                 }
 326
 327                 [MonoTODO ("CAS support is experimental (and unsupported). Imperative mode is not implemented.")]
 328                 public void PermitOnly ()
 329                 {
 330                         if (!SecurityManager.SecurityEnabled)
 331                                 return;
 332
 333                         foreach (IPermission p in list) {
 334                                 // note: we ignore non-CAS permissions
 335                                 if (p is IStackWalk) {
 336                                         throw new NotSupportedException ("Currently only declarative Deny are supported.");
 337                                 }
 338                         }
 339                 }
 340
 341                 public bool ContainsNonCodeAccessPermissions ()
 342                 {
 343                         if (list.Count > 0) {
 344                                 foreach (IPermission p in list) {
 345                                         if (! p.GetType ().IsSubclassOf (typeof (CodeAccessPermission)))
 346                                                 return true;
 347                                 }
 348                         }
 349                         return false;
 350                 }
 351
 352                 // FIXME little documentation in Fx 2.0 beta 1
 353                 public static byte[] ConvertPermissionSet (string inFormat, byte[] inData, string outFormat)
 354                 {
 355                         if (inFormat == null)
 356                                 throw new ArgumentNullException ("inFormat");
 357                         if (outFormat == null)
 358                                 throw new ArgumentNullException ("outFormat");
 359                         if (inData == null)
 360                                 return null;
 361
 362                         if (inFormat == outFormat)
 363                                 return inData;
 364
 365                         PermissionSet ps = null;
 366
 367                         if (inFormat == "BINARY") {
 368                                 if (outFormat.StartsWith ("XML")) {
 369                                         using (MemoryStream ms = new MemoryStream (inData)) {
 370                                                 BinaryFormatter formatter = new BinaryFormatter ();
 371                                                 ps = (PermissionSet) formatter.Deserialize (ms);
 372                                                 ms.Close ();
 373                                         }
 374                                         string xml = ps.ToString ();
 375                                         switch (outFormat) {
 376                                                 case "XML":
 377                                                 case "XMLASCII":
 378                                                         return Encoding.ASCII.GetBytes (xml);
 379                                                 case "XMLUNICODE":
 380                                                         return Encoding.Unicode.GetBytes (xml);
 381                                         }
 382                                 }
 383                         }
 384                         else if (inFormat.StartsWith ("XML")) {
 385                                 if (outFormat == "BINARY") {
 386                                         string xml = null;
 387                                         switch (inFormat) {
 388                                                 case "XML":
 389                                                 case "XMLASCII":
 390                                                         xml = Encoding.ASCII.GetString (inData);
 391                                                         break;
 392                                                 case "XMLUNICODE":
 393                                                         xml = Encoding.Unicode.GetString (inData);
 394                                                         break;
 395                                         }
 396                                         if (xml != null) {
 397                                                 ps = new PermissionSet (PermissionState.None);
 398                                                 ps.FromXml (SecurityElement.FromString (xml));
 399
 400                                                 MemoryStream ms = new MemoryStream ();
 401                                                 BinaryFormatter formatter = new BinaryFormatter ();
 402                                                 formatter.Serialize (ms, ps);
 403                                                 ms.Close ();
 404                                                 return ms.ToArray ();
 405                                         }
 406                                 }
 407                                 else if (outFormat.StartsWith ("XML")) {
 408                                         string msg = String.Format (Locale.GetText ("Can't convert from {0} to {1}"), inFormat, outFormat);
 409                                         throw new XmlSyntaxException (msg);
 410                                 }
 411                         }
 412                         else {
 413                                 // unknown inFormat, returns null
 414                                 return null;
 415                         }
 416                         // unknown outFormat, throw
 417                         throw new SerializationException (String.Format (Locale.GetText ("Unknown output format {0}."), outFormat));
 418                 }
 419
 420                 public IPermission GetPermission (Type permClass)
 421                 {
 422                         if ((permClass == null) || (list.Count == 0))
 423                                 return null;
 424
 425                         foreach (object o in list) {
 426                                 if ((o != null) && o.GetType ().Equals (permClass))
 427                                         return (IPermission) o;
 428                         }
 429                         // it's normal to return null for unrestricted sets
 430                         return null;
 431                 }
 432
 433                 public PermissionSet Intersect (PermissionSet other)
 434                 {
 435                         // no intersection possible
 436                         if ((other == null) || (other.IsEmpty ()) || (this.IsEmpty ()))
 437                                 return null;
 438
 439                         PermissionState state = PermissionState.None;
 440                         if (this.IsUnrestricted () && other.IsUnrestricted ())
 441                                 state = PermissionState.Unrestricted;
 442
 443                         PermissionSet interSet = null;
 444                         // much simpler with 2.0
 445                         if (state == PermissionState.Unrestricted) {
 446                                 interSet = new PermissionSet (state);
 447                         } else if (this.IsUnrestricted ()) {
 448                                 interSet = other.Copy ();
 449                         } else if (other.IsUnrestricted ()) {
 450                                 interSet = this.Copy ();
 451                         } else {
 452                                 interSet = new PermissionSet (state);
 453                                 InternalIntersect (interSet, this, other, false);
 454                         }
 455                         return interSet;
 456                 }
 457
 458                 internal void InternalIntersect (PermissionSet intersect, PermissionSet a, PermissionSet b, bool unrestricted)
 459                 {
 460                         foreach (IPermission p in b.list) {
 461                                 // for every type in both list
 462                                 IPermission i = a.GetPermission (p.GetType ());
 463                                 if (i != null) {
 464                                         // add intersection for this type
 465                                         intersect.AddPermission (p.Intersect (i));
 466                                 }
 467                                 // unrestricted is possible for indentity permissions
 468                                 else if (unrestricted) {
 469                                         intersect.AddPermission (p);
 470                                 }
 471                                 // or reject!
 472                         }
 473                 }
 474
 475                 public bool IsEmpty ()
 476                 {
 477                         // note: Unrestricted isn't empty
 478                         if (state == PermissionState.Unrestricted)
 479                                 return false;
 480                         if ((list == null) || (list.Count == 0))
 481                                 return true;
 482                         // the set may include some empty permissions
 483                         foreach (IPermission p in list) {
 484                                 // empty == fully restricted == IsSubsetOf(null) == true
 485                                 if (!p.IsSubsetOf (null))
 486                                         return false;
 487                         }
 488                         return true;
 489                 }
 490
 491                 public bool IsUnrestricted ()
 492                 {
 493                         return (state == PermissionState.Unrestricted);
 494                 }
 495
 496                 public IPermission RemovePermission (Type permClass)
 497                 {
 498                         if ((permClass == null) || _readOnly)
 499                                 return null;
 500
 501                         foreach (object o in list) {
 502                                 if (o.GetType ().Equals (permClass)) {
 503                                         list.Remove (o);
 504                                         return (IPermission) o;
 505                                 }
 506                         }
 507                         return null;
 508                 }
 509
 510                 public IPermission SetPermission (IPermission perm)
 511                 {
 512                         if ((perm == null) || _readOnly)
 513                                 return perm;
 514                         IUnrestrictedPermission u = (perm as IUnrestrictedPermission);
 515                         if (u == null) {
 516                                 state = PermissionState.None;
 517                         } else {
 518                                 state = u.IsUnrestricted () ? state : PermissionState.None;
 519                         }
 520                         RemovePermission (perm.GetType ());
 521                         list.Add (perm);
 522                         return perm;
 523                 }
 524
 525                 public override string ToString ()
 526                 {
 527                         return ToXml ().ToString ();
 528                 }
 529
 530                 public virtual SecurityElement ToXml ()
 531                 {
 532                         SecurityElement se = new SecurityElement (tagName);
 533                         se.AddAttribute ("class", GetType ().FullName);
 534                         se.AddAttribute ("version", version.ToString ());
 535                         if (state == PermissionState.Unrestricted)
 536                                 se.AddAttribute ("Unrestricted", "true");
 537
 538                         // required for permissions that do not implement IUnrestrictedPermission
 539                         foreach (IPermission p in list) {
 540                                 se.AddChild (p.ToXml ());
 541                         }
 542                         return se;
 543                 }
 544
 545                 public PermissionSet Union (PermissionSet other)
 546                 {
 547                         if (other == null)
 548                                 return this.Copy ();
 549
 550                         PermissionSet copy = null;
 551                         if (this.IsUnrestricted () || other.IsUnrestricted ()) {
 552                                 // there are no child elements in unrestricted permission sets
 553                                 return new PermissionSet (PermissionState.Unrestricted);
 554                         } else {
 555                                 copy = this.Copy ();
 556                                 // PermissionState.None -> copy all permissions
 557                                 foreach (IPermission p in other.list) {
 558                                         copy.AddPermission (p);
 559                                 }
 560                         }
 561                         return copy;
 562                 }
 563
 564                 public virtual int Count {
 565                         get { return list.Count; }
 566                 }
 567
 568                 public virtual bool IsSynchronized {
 569                         get { return list.IsSynchronized; }
 570                 }
 571
 572                 public virtual bool IsReadOnly {
 573                         // always false (as documented) but the PermissionSet can be read-only
 574                         // e.g. in a PolicyStatement
 575                         get { return false; }
 576                 }
 577
 578                 public virtual object SyncRoot {
 579                         get { return this; }
 580                 }
 581
 582                 internal bool DeclarativeSecurity {
 583                         get { return _declsec; }
 584                         set { _declsec = value; }
 585                 }
 586
 587                 [MonoTODO ("may not be required")]
 588                 void IDeserializationCallback.OnDeserialization (object sender)
 589                 {
 590                 }
 591
 592                 [ComVisible (false)]
 593                 public override bool Equals (object obj)
 594                 {
 595                         if (obj == null)
 596                                 return false;
 597                         PermissionSet ps = (obj as PermissionSet);
 598                         if (ps == null)
 599                                 return false;
 600                         if (state != ps.state)
 601                                 return false;
 602                         if (list.Count != ps.Count)
 603                                 return false;
 604
 605                         for (int i=0; i < list.Count; i++) {
 606                                 bool found = false;
 607                                 for (int j=0; i < ps.list.Count; j++) {
 608                                         if (list [i].Equals (ps.list [j])) {
 609                                                 found = true;
 610                                                 break;
 611                                         }
 612                                 }
 613                                 if (!found)
 614                                         return false;
 615                         }
 616                         return true;
 617                 }
 618
 619                 [ComVisible (false)]
 620                 public override int GetHashCode ()
 621                 {
 622                         return (list.Count == 0) ? (int) state : base.GetHashCode ();
 623                 }
 624
 625                 // FIXME what's it doing here? There's probably a reason this was added here.
 626                 static public void RevertAssert ()
 627                 {
 628                         CodeAccessPermission.RevertAssert ();
 629                 }
 630
 631                 // internal
 632
 633                 internal PolicyLevel Resolver {
 634                         get { return _policyLevel; }
 635                         set { _policyLevel = value; }
 636                 }
 637
 638                 internal void SetReadOnly (bool value)
 639                 {
 640                         _readOnly = value;
 641                 }
 642
 643                 private bool AllIgnored ()
 644                 {
 645                         if (_ignored == null)
 646                                 throw new NotSupportedException ("bad bad bad");
 647
 648                         for (int i=0; i < _ignored.Length; i++) {
 649                                 if (!_ignored [i])
 650                                         return false;
 651                         }
 652                         // everything is ignored (i.e. non-CAS permission or asserted permission).
 653                         return true;
 654                 }
 655
 656                 // 2.0 metadata format
 657
 658                 internal static PermissionSet CreateFromBinaryFormat (byte[] data)
 659                 {
 660                         if ((data == null) || (data [0] != 0x2E) || (data.Length < 2)) {
 661                                 string msg = Locale.GetText ("Invalid data in 2.0 metadata format.");
 662                                 throw new SecurityException (msg);
 663                         }
 664
 665                         int pos = 1;
 666                         int numattr = ReadEncodedInt (data, ref pos);
 667                         PermissionSet ps = new PermissionSet (PermissionState.None);
 668                         for (int i = 0; i < numattr; i++) {
 669                                 IPermission p = ProcessAttribute (data, ref pos);
 670                                 if (p == null) {
 671                                         string msg = Locale.GetText ("Unsupported data found in 2.0 metadata format.");
 672                                         throw new SecurityException (msg);
 673                                 }
 674                                 ps.AddPermission (p);
 675                         }
 676                         return ps;
 677                 }
 678
 679                 internal static int ReadEncodedInt (byte[] data, ref int position)
 680                 {
 681                         int len = 0;
 682                         if ((data [position] & 0x80) == 0) {
 683                                 len = data [position];
 684                                 position ++;
 685                         } else if ((data [position] & 0x40) == 0) {
 686                                 len = ((data [position] & 0x3f) << 8 | data [position + 1]);
 687                                 position += 2;
 688                         } else {
 689                                 len = (((data [position] & 0x1f) << 24) | (data [position + 1] << 16) |
 690                                         (data [position + 2] << 8) | (data [position + 3]));
 691                                 position += 4;
 692                         }
 693                         return len;
 694                 }
 695
 696                 static object[] action = new object [1] { (SecurityAction) 0 };
 697
 698                 // TODO: add support for arrays and enums (2.0)
 699                 internal static IPermission ProcessAttribute (byte[] data, ref int position)
 700                 {
 701                         int clen = ReadEncodedInt (data, ref position);
 702                         string cnam = Encoding.UTF8.GetString (data, position, clen);
 703                         position += clen;
 704
 705                         Type secattr = Type.GetType (cnam);
 706                         SecurityAttribute sa = (Activator.CreateInstance (secattr, action) as SecurityAttribute);
 707                         if (sa == null)
 708                                 return null;
 709
 710                         /*int optionalParametersLength =*/ ReadEncodedInt (data, ref position);
 711                         int numberOfParameters = ReadEncodedInt (data, ref position);
 712                         for (int j=0; j < numberOfParameters; j++) {
 713                                 bool property = false;
 714                                 switch (data [position++]) {
 715                                 case 0x53: // field (technically possible and working)
 716                                         property = false;
 717                                         break;
 718                                 case 0x54: // property (common case)
 719                                         property = true;
 720                                         break;
 721                                 default:
 722                                         return null;
 723                                 }
 724
 725                                 bool array = false;
 726                                 byte type = data [position++];
 727                                 if (type == 0x1D) {
 728                                         array = true;
 729                                         type = data [position++];
 730                                 }
 731
 732                                 int plen = ReadEncodedInt (data, ref position);
 733                                 string pnam = Encoding.UTF8.GetString (data, position, plen);
 734                                 position += plen;
 735
 736                                 int arrayLength = 1;
 737                                 if (array) {
 738                                         arrayLength = BitConverter.ToInt32 (data, position);
 739                                         position += 4;
 740                                 }
 741
 742                                 object obj = null;
 743                                 object[] arrayIndex = null;
 744                                 for (int i = 0; i < arrayLength; i++) {
 745                                         if (array) {
 746                                                 // TODO - setup index (2.0)
 747                                         }
 748
 749                                         // sadly type values doesn't match ther TypeCode enum :(
 750                                         switch (type) {
 751                                         case 0x02: // MONO_TYPE_BOOLEAN
 752                                                 obj = (object) Convert.ToBoolean (data [position++]);
 753                                                 break;
 754                                         case 0x03: // MONO_TYPE_CHAR
 755                                                 obj = (object) Convert.ToChar (data [position]);
 756                                                 position += 2;
 757                                                 break;
 758                                         case 0x04: // MONO_TYPE_I1
 759                                                 obj = (object) Convert.ToSByte (data [position++]);
 760                                                 break;
 761                                         case 0x05: // MONO_TYPE_U1
 762                                                 obj = (object) Convert.ToByte (data [position++]);
 763                                                 break;
 764                                         case 0x06: // MONO_TYPE_I2
 765                                                 obj = (object) Convert.ToInt16 (data [position]);
 766                                                 position += 2;
 767                                                 break;
 768                                         case 0x07: // MONO_TYPE_U2
 769                                                 obj = (object) Convert.ToUInt16 (data [position]);
 770                                                 position += 2;
 771                                                 break;
 772                                         case 0x08: // MONO_TYPE_I4
 773                                                 obj = (object) Convert.ToInt32 (data [position]);
 774                                                 position += 4;
 775                                                 break;
 776                                         case 0x09: // MONO_TYPE_U4
 777                                                 obj = (object) Convert.ToUInt32 (data [position]);
 778                                                 position += 4;
 779                                                 break;
 780                                         case 0x0A: // MONO_TYPE_I8
 781                                                 obj = (object) Convert.ToInt64 (data [position]);
 782                                                 position += 8;
 783                                                 break;
 784                                         case 0x0B: // MONO_TYPE_U8
 785                                                 obj = (object) Convert.ToUInt64 (data [position]);
 786                                                 position += 8;
 787                                                 break;
 788                                         case 0x0C: // MONO_TYPE_R4
 789                                                 obj = (object) Convert.ToSingle (data [position]);
 790                                                 position += 4;
 791                                                 break;
 792                                         case 0x0D: // MONO_TYPE_R8
 793                                                 obj = (object) Convert.ToDouble (data [position]);
 794                                                 position += 8;
 795                                                 break;
 796                                         case 0x0E: // MONO_TYPE_STRING
 797                                                 string s = null;
 798                                                 if (data [position] != 0xFF) {
 799                                                         int slen = ReadEncodedInt (data, ref position);
 800                                                         s = Encoding.UTF8.GetString (data, position, slen);
 801                                                         position += slen;
 802                                                 } else {
 803                                                         position++;
 804                                                 }
 805                                                 obj = (object) s;
 806                                                 break;
 807                                         case 0x50: // special for TYPE
 808                                                 int tlen = ReadEncodedInt (data, ref position);
 809                                                 obj = (object) Type.GetType (Encoding.UTF8.GetString (data, position, tlen));
 810                                                 position += tlen;
 811                                                 break;
 812                                         default:
 813                                                 return null; // unsupported
 814                                         }
 815
 816                                         if (property) {
 817                                                 PropertyInfo pi = secattr.GetProperty (pnam);
 818                                                 pi.SetValue (sa, obj, arrayIndex);
 819                                         } else {
 820                                                 FieldInfo fi = secattr.GetField (pnam);
 821                                                 fi.SetValue (sa, obj);
 822                                         }
 823                                 }
 824                         }
 825                         return sa.CreatePermission ();
 826                 }
 827         }
 828 }