mcs/class/referencesource/System.Xml/System/Xml/XmlSecureResolver.cs

   1 //------------------------------------------------------------------------------
   2 // <copyright file="XmlSecureResolver.cs" company="Microsoft">
   3 //     Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 // <owner current="true" primary="true">[....]</owner>
   6 //------------------------------------------------------------------------------
   7
   8 namespace System.Xml {
   9     using System.Net;
  10     using System.Security;
  11     using System.Security.Policy;
  12     using System.Security.Permissions;
  13     using System.Runtime.Versioning;
  14
  15     [PermissionSetAttribute(SecurityAction.InheritanceDemand, Name = "FullTrust")]
  16     public partial class XmlSecureResolver : XmlResolver {
  17         XmlResolver resolver;
  18         PermissionSet permissionSet;
  19
  20         public XmlSecureResolver(XmlResolver resolver, string securityUrl) : this(resolver, CreateEvidenceForUrl(securityUrl)) {}
  21
  22         public XmlSecureResolver(XmlResolver resolver, Evidence evidence) : this(resolver, SecurityManager.GetStandardSandbox(evidence)) {}
  23
  24         public XmlSecureResolver(XmlResolver resolver, PermissionSet permissionSet) {
  25             this.resolver = resolver;
  26             this.permissionSet = permissionSet;
  27         }
  28
  29         public override ICredentials Credentials {
  30             set { resolver.Credentials = value; }
  31         }
  32
  33         public override object GetEntity(Uri absoluteUri, string role, Type ofObjectToReturn) {
  34             permissionSet.PermitOnly();
  35             return resolver.GetEntity(absoluteUri, role, ofObjectToReturn);
  36         }
  37
  38         [ResourceConsumption(ResourceScope.Machine)]
  39         [ResourceExposure(ResourceScope.Machine)]
  40         public override Uri ResolveUri(Uri baseUri, string relativeUri) {
  41             return resolver.ResolveUri(baseUri, relativeUri);
  42         }
  43
  44         public static Evidence CreateEvidenceForUrl(string securityUrl) {
  45             Evidence evidence = new Evidence();
  46             if (securityUrl != null && securityUrl.Length > 0) {
  47                 evidence.AddHostEvidence(new Url(securityUrl));
  48                 evidence.AddHostEvidence(Zone.CreateFromUrl(securityUrl));
  49                 Uri uri = new Uri(securityUrl, UriKind.RelativeOrAbsolute);
  50                 if (uri.IsAbsoluteUri && !uri.IsFile) {
  51                     evidence.AddHostEvidence(Site.CreateFromUrl(securityUrl));
  52                 }
  53
  54                 // Allow same directory access for UNCs (SQLBUDT 394535)
  55                 if (uri.IsAbsoluteUri && uri.IsUnc) {
  56                     string uncDir = System.IO.Path.GetDirectoryName(uri.LocalPath);
  57                     if (uncDir != null && uncDir.Length != 0) {
  58                         evidence.AddHostEvidence(new UncDirectory(uncDir));
  59                     }
  60                 }
  61             }
  62             return evidence;
  63         }
  64
  65         [Serializable]
  66         private class UncDirectory : EvidenceBase, IIdentityPermissionFactory {
  67             private string uncDir;
  68
  69             public UncDirectory(string uncDirectory) {
  70                 this.uncDir = uncDirectory;
  71             }
  72
  73             public IPermission CreateIdentityPermission(Evidence evidence) {
  74                 return new FileIOPermission(FileIOPermissionAccess.Read, uncDir);
  75             }
  76
  77             public override EvidenceBase Clone()
  78             {
  79                 return new UncDirectory(uncDir);
  80             }
  81
  82             private SecurityElement ToXml() {
  83                 SecurityElement root = new SecurityElement("System.Xml.XmlSecureResolver");
  84                 root.AddAttribute("version", "1");
  85                 root.AddChild(new SecurityElement("UncDirectory", uncDir));
  86                 return root;
  87             }
  88
  89             public override string ToString() {
  90                 return ToXml().ToString();
  91             }
  92         }
  93     }
  94 }