class/corlib/System.Security/CodeAccessPermission.cs

   1 //
   2 // System.Security.CodeAccessPermission.cs
   3 //
   4 // Authors:
   5 //      Miguel de Icaza (miguel@ximian.com)
   6 //      Nick Drochak, ndrochak@gol.com
   7 //      Sebastien Pouliot  <sebastien@ximian.com>
   8 //
   9 // (C) Ximian, Inc. http://www.ximian.com
  10 // Copyright (C) 2001 Nick Drochak, All Rights Reserved
  11 // Portions (C) 2004 Motus Technologies Inc. (http://www.motus.com)
  12 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
  13 //
  14 // Permission is hereby granted, free of charge, to any person obtaining
  15 // a copy of this software and associated documentation files (the
  16 // "Software"), to deal in the Software without restriction, including
  17 // without limitation the rights to use, copy, modify, merge, publish,
  18 // distribute, sublicense, and/or sell copies of the Software, and to
  19 // permit persons to whom the Software is furnished to do so, subject to
  20 // the following conditions:
  21 //
  22 // The above copyright notice and this permission notice shall be
  23 // included in all copies or substantial portions of the Software.
  24 //
  25 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  26 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  27 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  28 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  29 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  30 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  31 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  32 //
  33
  34 using System.Diagnostics;
  35 using System.Globalization;
  36 using System.Reflection;
  37 using System.Runtime.CompilerServices;
  38 using System.Runtime.InteropServices;
  39 using System.Security.Permissions;
  40 using System.Threading;
  41
  42 namespace System.Security {
  43
  44         [Serializable]
  45         [SecurityPermission (SecurityAction.InheritanceDemand, ControlEvidence = true, ControlPolicy = true)]
  46         [ComVisible (true)]
  47         [MonoTODO ("CAS support is experimental (and unsupported).")]
  48         public abstract class CodeAccessPermission : IPermission, ISecurityEncodable, IStackWalk {
  49
  50
  51                 protected CodeAccessPermission ()
  52                 {
  53                 }
  54
  55                 [MonoTODO ("CAS support is experimental (and unsupported). Imperative mode is not implemented.")]
  56                 public void Assert ()
  57                 {
  58                         new PermissionSet (this).Assert ();
  59                 }
  60
  61                 internal bool CheckAssert (CodeAccessPermission asserted)
  62                 {
  63                         if (asserted == null)
  64                                 return false;
  65                         if (asserted.GetType () != this.GetType ())
  66                                 return false;
  67                         return IsSubsetOf (asserted);
  68                 }
  69
  70                 internal bool CheckDemand (CodeAccessPermission target)
  71                 {
  72                         if (target == null)
  73                                 return false;
  74                         if (target.GetType () != this.GetType ())
  75                                 return false;
  76                         return IsSubsetOf (target);
  77                 }
  78
  79                 internal bool CheckDeny (CodeAccessPermission denied)
  80                 {
  81                         if (denied == null)
  82                                 return true;
  83                         Type t = denied.GetType ();
  84                         if (t != this.GetType ())
  85                                 return true;
  86                         IPermission inter = Intersect (denied);
  87                         if (inter == null)
  88                                 return true;
  89                         // sadly that's not enough :( at this stage we must also check
  90                         // if an empty (PermissionState.None) is a subset of the denied
  91                         // (which is like a empty intersection looks like for flag based
  92                         // permissions, e.g. AspNetHostingPermission).
  93                         return denied.IsSubsetOf (PermissionBuilder.Create (t));
  94                 }
  95
  96                 internal bool CheckPermitOnly (CodeAccessPermission target)
  97                 {
  98                         if (target == null)
  99                                 return false;
 100                         if (target.GetType () != this.GetType ())
 101                                 return false;
 102                         return IsSubsetOf (target);
 103                 }
 104
 105                 public abstract IPermission Copy ();
 106
 107                 public void Demand ()
 108                 {
 109                         // note: here we're sure it's a CAS demand
 110                         if (!SecurityManager.SecurityEnabled)
 111                                 return;
 112
 113                         // skip frames until we get the caller (of our caller)
 114                         new PermissionSet (this).CasOnlyDemand (3);
 115                 }
 116
 117                 [MonoTODO ("CAS support is experimental (and unsupported). Imperative mode is not implemented.")]
 118                 public void Deny ()
 119                 {
 120                         new PermissionSet (this).Deny ();
 121                 }
 122
 123                 [ComVisible (false)]
 124                 public override bool Equals (object obj)
 125                 {
 126                         if (obj == null)
 127                                 return false;
 128                         if (obj.GetType () != this.GetType ())
 129                                 return false;
 130                         CodeAccessPermission cap = (obj as CodeAccessPermission);
 131                         return (IsSubsetOf (cap) && cap.IsSubsetOf (this));
 132                 }
 133
 134                 public abstract void FromXml (SecurityElement elem);
 135
 136                 [ComVisible (false)]
 137                 public override int GetHashCode ()
 138                 {
 139                         return base.GetHashCode ();
 140                 }
 141
 142                 public abstract IPermission Intersect (IPermission target);
 143
 144                 public abstract bool IsSubsetOf (IPermission target);
 145
 146                 public override string ToString ()
 147                 {
 148                         SecurityElement elem = ToXml ();
 149                         return elem.ToString ();
 150                 }
 151
 152                 public abstract SecurityElement ToXml ();
 153
 154                 public virtual IPermission Union (IPermission other)
 155                 {
 156                         if (null != other)
 157                                 throw new System.NotSupportedException (); // other is not null.
 158                         return null;
 159                 }
 160
 161                 [MonoTODO ("CAS support is experimental (and unsupported). Imperative mode is not implemented.")]
 162                 public void PermitOnly ()
 163                 {
 164                         new PermissionSet (this).PermitOnly ();
 165                 }
 166
 167                 [MonoTODO ("CAS support is experimental (and unsupported). Imperative mode is not implemented.")]
 168                 public static void RevertAll ()
 169                 {
 170                         if (!SecurityManager.SecurityEnabled)
 171                                 return;
 172
 173                         SecurityFrame sf = new SecurityFrame (1);
 174                         bool revert = false;
 175                         if ((sf.Assert != null) && !sf.Assert.DeclarativeSecurity) {
 176                                 revert = true;
 177                                 throw new NotSupportedException ("Currently only declarative Assert are supported.");
 178                         }
 179                         if ((sf.Deny != null) && !sf.Deny.DeclarativeSecurity) {
 180                                 revert = true;
 181                                 throw new NotSupportedException ("Currently only declarative Deny are supported.");
 182                         }
 183                         if ((sf.PermitOnly != null) && !sf.PermitOnly.DeclarativeSecurity) {
 184                                 revert = true;
 185                                 throw new NotSupportedException ("Currently only declarative PermitOnly are supported.");
 186                         }
 187
 188                         if (!revert) {
 189                                 string msg = Locale.GetText ("No stack modifiers are present on the current stack frame.");
 190                                 // FIXME: we don't (yet) support imperative stack modifiers
 191                                 msg += Environment.NewLine + "Currently only declarative stack modifiers are supported.";
 192                                 throw new ExecutionEngineException (msg);
 193                         }
 194                 }
 195
 196                 [MonoTODO ("CAS support is experimental (and unsupported). Imperative mode is not implemented.")]
 197                 public static void RevertAssert ()
 198                 {
 199                         if (!SecurityManager.SecurityEnabled)
 200                                 return;
 201
 202                         SecurityFrame sf = new SecurityFrame (1);
 203                         if ((sf.Assert != null) && !sf.Assert.DeclarativeSecurity) {
 204                                 throw new NotSupportedException ("Currently only declarative Assert are supported.");
 205                         } else {
 206                                 // we can't revert declarative security (or an empty frame) imperatively
 207                                 ThrowExecutionEngineException (SecurityAction.Assert);
 208                         }
 209                 }
 210
 211                 [MonoTODO ("CAS support is experimental (and unsupported). Imperative mode is not implemented.")]
 212                 public static void RevertDeny ()
 213                 {
 214                         if (!SecurityManager.SecurityEnabled)
 215                                 return;
 216
 217                         SecurityFrame sf = new SecurityFrame (1);
 218                         if ((sf.Deny != null) && !sf.Deny.DeclarativeSecurity) {
 219                                 throw new NotSupportedException ("Currently only declarative Deny are supported.");
 220                         } else {
 221                                 // we can't revert declarative security (or an empty frame) imperatively
 222                                 ThrowExecutionEngineException (SecurityAction.Deny);
 223                         }
 224                 }
 225
 226                 [MonoTODO ("CAS support is experimental (and unsupported). Imperative mode is not implemented.")]
 227                 public static void RevertPermitOnly ()
 228                 {
 229                         if (!SecurityManager.SecurityEnabled)
 230                                 return;
 231
 232                         SecurityFrame sf = new SecurityFrame (1);
 233                         if ((sf.PermitOnly != null) && sf.PermitOnly.DeclarativeSecurity) {
 234                                 throw new NotSupportedException ("Currently only declarative PermitOnly are supported.");
 235                         } else {
 236                                 // we can't revert declarative security (or an empty frame) imperatively
 237                                 ThrowExecutionEngineException (SecurityAction.PermitOnly);
 238                         }
 239                 }
 240
 241                 // Internal helpers methods
 242
 243                 // snippet moved from FileIOPermission (nickd) to be reused in all derived classes
 244                 internal SecurityElement Element (int version)
 245                 {
 246                         SecurityElement se = new SecurityElement ("IPermission");
 247                         Type type = this.GetType ();
 248                         se.AddAttribute ("class", type.FullName + ", " + type.Assembly.ToString ().Replace ('\"', '\''));
 249                         se.AddAttribute ("version", version.ToString ());
 250                         return se;
 251                 }
 252
 253                 internal static PermissionState CheckPermissionState (PermissionState state, bool allowUnrestricted)
 254                 {
 255                         string msg;
 256                         switch (state) {
 257                         case PermissionState.None:
 258                                 break;
 259                         case PermissionState.Unrestricted:
 260                                 // unrestricted permissions are possible for identiy permissions
 261                                 break;
 262                         default:
 263                                 msg = String.Format (Locale.GetText ("Invalid enum {0}"), state);
 264                                 throw new ArgumentException (msg, "state");
 265                         }
 266                         return state;
 267                 }
 268
 269                 internal static int CheckSecurityElement (SecurityElement se, string parameterName, int minimumVersion, int maximumVersion)
 270                 {
 271                         if (se == null)
 272                                 throw new ArgumentNullException (parameterName);
 273
 274                         // Tag is case-sensitive
 275                         if (se.Tag != "IPermission") {
 276                                 string msg = String.Format (Locale.GetText ("Invalid tag {0}"), se.Tag);
 277                                 throw new ArgumentException (msg, parameterName);
 278                         }
 279
 280                         // Note: we do not care about the class attribute at
 281                         // this stage (in fact we don't even if the class
 282                         // attribute is present or not). Anyway the object has
 283                         // already be created, with success, if we're loading it
 284
 285                         // we assume minimum version if no version number is supplied
 286                         int version = minimumVersion;
 287                         string v = se.Attribute ("version");
 288                         if (v != null) {
 289                                 try {
 290                                         version = Int32.Parse (v);
 291                                 }
 292                                 catch (Exception e) {
 293                                         string msg = Locale.GetText ("Couldn't parse version from '{0}'.");
 294                                         msg = String.Format (msg, v);
 295                                         throw new ArgumentException (msg, parameterName, e);
 296                                 }
 297                         }
 298
 299                         if ((version < minimumVersion) || (version > maximumVersion)) {
 300                                 string msg = Locale.GetText ("Unknown version '{0}', expected versions between ['{1}','{2}'].");
 301                                 msg = String.Format (msg, version, minimumVersion, maximumVersion);
 302                                 throw new ArgumentException (msg, parameterName);
 303                         }
 304                         return version;
 305                 }
 306
 307                 // must be called after CheckSecurityElement (i.e. se != null)
 308                 internal static bool IsUnrestricted (SecurityElement se)
 309                 {
 310                         string value = se.Attribute ("Unrestricted");
 311                         if (value == null)
 312                                 return false;
 313                         return (String.Compare (value, Boolean.TrueString, true, CultureInfo.InvariantCulture) == 0);
 314                 }
 315
 316                 internal bool ProcessFrame (SecurityFrame frame)
 317                 {
 318                         // 1. CheckPermitOnly
 319                         if (frame.PermitOnly != null) {
 320                                 // the demanded permission must be in one of the permitted...
 321                                 bool permit = frame.PermitOnly.IsUnrestricted ();
 322                                 if (!permit) {
 323                                         // check individual permissions
 324                                         foreach (IPermission p in frame.PermitOnly) {
 325                                                 if (CheckPermitOnly (p as CodeAccessPermission)) {
 326                                                         permit = true;
 327                                                         break;
 328                                                 }
 329                                         }
 330                                 }
 331                                 if (!permit) {
 332                                         // ...or else we throw
 333                                         ThrowSecurityException (this, "PermitOnly", frame, SecurityAction.Demand, null);
 334                                 }
 335                         }
 336
 337                         // 2. CheckDeny
 338                         if (frame.Deny != null) {
 339                                 // special case where everything is denied (i.e. no child to be processed)
 340                                 if (frame.Deny.IsUnrestricted ())
 341                                         ThrowSecurityException (this, "Deny", frame, SecurityAction.Demand, null);
 342                                 foreach (IPermission p in frame.Deny) {
 343                                         if (!CheckDeny (p as CodeAccessPermission))
 344                                                 ThrowSecurityException (this, "Deny", frame, SecurityAction.Demand, p);
 345                                 }
 346                         }
 347
 348                         // 3. CheckAssert
 349                         if (frame.Assert != null) {
 350                                 if (frame.Assert.IsUnrestricted ())
 351                                         return true; // remove permission and continue stack walk
 352                                 foreach (IPermission p in frame.Assert) {
 353                                         if (CheckAssert (p as CodeAccessPermission)) {
 354                                                 return true; // remove permission and continue stack walk
 355                                         }
 356                                 }
 357                         }
 358
 359                         // continue the stack walk
 360                         return false;
 361                 }
 362
 363                 internal static void ThrowInvalidPermission (IPermission target, Type expected)
 364                 {
 365                         string msg = Locale.GetText ("Invalid permission type '{0}', expected type '{1}'.");
 366                         msg = String.Format (msg, target.GetType (), expected);
 367                         throw new ArgumentException (msg, "target");
 368                 }
 369
 370                 internal static void ThrowExecutionEngineException (SecurityAction stackmod)
 371                 {
 372                         string msg = Locale.GetText ("No {0} modifier is present on the current stack frame.");
 373                         // FIXME: we don't (yet) support imperative stack modifiers
 374                         msg += Environment.NewLine + "Currently only declarative stack modifiers are supported.";
 375                         throw new ExecutionEngineException (String.Format (msg, stackmod));
 376                 }
 377
 378                 internal static void ThrowSecurityException (object demanded, string message, SecurityFrame frame,
 379                         SecurityAction action, IPermission failed)
 380                 {
 381 #if NET_2_1
 382                         throw new SecurityException (message);
 383 #else
 384                         Assembly a = frame.Assembly;
 385                         throw new SecurityException (Locale.GetText (message),
 386                                 a.UnprotectedGetName (), a.GrantedPermissionSet,
 387                                 a.DeniedPermissionSet, frame.Method, action, demanded,
 388                                 failed, a.UnprotectedGetEvidence ());
 389 #endif
 390                 }
 391         }
 392 }