mcs/class/referencesource/mscorlib/system/security/policy/hashmembershipcondition.cs

   1 // ==++==
   2 //
   3 //   Copyright (c) Microsoft Corporation.  All rights reserved.
   4 //
   5 // ==--==
   6 // <OWNER>Microsoft</OWNER>
   7 //
   8
   9 //
  10 // HashMembershipCondition.cs
  11 //
  12 // Implementation of membership condition for hashes of assemblies.
  13 //
  14
  15 namespace System.Security.Policy {
  16     using System.Collections;
  17     using System.Runtime.Serialization;
  18     using System.Security;
  19     using System.Security.Cryptography;
  20     using System.Security.Util;
  21     using System.Security.Permissions;
  22     using System.Threading;
  23     using System.Globalization;
  24     using System.Diagnostics.Contracts;
  25
  26     [Serializable]
  27     [System.Runtime.InteropServices.ComVisible(true)]
  28     public sealed class HashMembershipCondition : ISerializable, IDeserializationCallback, IMembershipCondition, IReportMatchMembershipCondition {
  29         private byte[] m_value = null;
  30         private HashAlgorithm m_hashAlg = null;
  31         private SecurityElement m_element = null;
  32
  33         private object s_InternalSyncObject = null;
  34         private object InternalSyncObject {
  35             get {
  36                 if (s_InternalSyncObject == null) {
  37                     Object o = new Object();
  38                     Interlocked.CompareExchange(ref s_InternalSyncObject, o, null);
  39                 }
  40                 return s_InternalSyncObject;
  41             }
  42         }
  43
  44         internal HashMembershipCondition() {}
  45         private HashMembershipCondition (SerializationInfo info, StreamingContext context) {
  46             m_value = (byte[]) info.GetValue("HashValue", typeof(byte[]));
  47             string hashAlgorithm = (string) info.GetValue("HashAlgorithm", typeof(string));
  48             if (hashAlgorithm != null)
  49                 m_hashAlg = HashAlgorithm.Create(hashAlgorithm);
  50             else
  51                 m_hashAlg = new SHA1Managed();
  52         }
  53
  54         public HashMembershipCondition(HashAlgorithm hashAlg, byte[] value) {
  55             if (value == null)
  56                 throw new ArgumentNullException("value");
  57             if (hashAlg == null)
  58                 throw new ArgumentNullException("hashAlg");
  59             Contract.EndContractBlock();
  60
  61             m_value = new byte[value.Length];
  62             Array.Copy(value, m_value, value.Length);
  63             m_hashAlg = hashAlg;
  64         }
  65
  66         /// <internalonly/>
  67         [System.Security.SecurityCritical]
  68         void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context)
  69         {
  70             info.AddValue("HashValue", this.HashValue);
  71             info.AddValue("HashAlgorithm", this.HashAlgorithm.ToString());
  72         }
  73
  74         /// <internalonly/>
  75         void IDeserializationCallback.OnDeserialization (Object sender) {}
  76
  77         public HashAlgorithm HashAlgorithm {
  78             set {
  79                 if (value == null)
  80                     throw new ArgumentNullException("HashAlgorithm");
  81                 Contract.EndContractBlock();
  82                 m_hashAlg = value;
  83             }
  84             get {
  85                 if (m_hashAlg == null && m_element != null)
  86                     ParseHashAlgorithm();
  87                 return m_hashAlg;
  88             }
  89         }
  90
  91         public byte[] HashValue {
  92             set {
  93                 if (value == null)
  94                     throw new ArgumentNullException("value");
  95                 Contract.EndContractBlock();
  96                 m_value = new byte[value.Length];
  97                 Array.Copy(value, m_value, value.Length);
  98             }
  99             get {
 100                 if (m_value == null && m_element != null)
 101                     ParseHashValue();
 102                 if (m_value == null)
 103                     return null;
 104
 105                 byte[] value = new byte[m_value.Length];
 106                 Array.Copy(m_value, value, m_value.Length);
 107                 return value;
 108             }
 109         }
 110
 111         public bool Check(Evidence evidence) {
 112             object usedEvidence = null;
 113             return (this as IReportMatchMembershipCondition).Check(evidence, out usedEvidence);
 114         }
 115
 116         bool IReportMatchMembershipCondition.Check(Evidence evidence, out object usedEvidence) {
 117             usedEvidence = null;
 118
 119             if (evidence == null)
 120                 return false;
 121
 122             Hash hash = evidence.GetHostEvidence<Hash>();
 123             if (hash != null) {
 124                 if (m_value == null && m_element != null)
 125                     ParseHashValue();
 126
 127                 if (m_hashAlg == null && m_element != null)
 128                     ParseHashAlgorithm();
 129
 130                 byte[] asmHash = null;
 131                 lock (InternalSyncObject) {
 132                     asmHash = hash.GenerateHash(m_hashAlg);
 133                 }
 134
 135                 if (asmHash != null && CompareArrays(asmHash, m_value)) {
 136                     usedEvidence = hash;
 137                     return true;
 138                 }
 139             }
 140
 141             return false;
 142         }
 143
 144         public IMembershipCondition Copy() {
 145             if (m_value == null && m_element != null)
 146                 ParseHashValue();
 147
 148             if (m_hashAlg == null && m_element != null)
 149                 ParseHashAlgorithm();
 150
 151             return new HashMembershipCondition(m_hashAlg, m_value);
 152         }
 153
 154         public SecurityElement ToXml() {
 155             return ToXml(null);
 156         }
 157
 158         public void FromXml(SecurityElement e) {
 159             FromXml(e, null);
 160         }
 161
 162         public SecurityElement ToXml(PolicyLevel level) {
 163             if (m_value == null && m_element != null)
 164                 ParseHashValue();
 165
 166             if (m_hashAlg == null && m_element != null)
 167                 ParseHashAlgorithm();
 168
 169             SecurityElement root = new SecurityElement("IMembershipCondition");
 170             XMLUtil.AddClassAttribute(root, this.GetType(), "System.Security.Policy.HashMembershipCondition");
 171             // If you hit this assert then most likely you are trying to change the name of this class.
 172             // This is ok as long as you change the hard coded string above and change the assert below.
 173             Contract.Assert(this.GetType().FullName.Equals("System.Security.Policy.HashMembershipCondition"), "Class name changed!");
 174
 175             root.AddAttribute("version", "1");
 176             if (m_value != null)
 177                 root.AddAttribute(s_tagHashValue, Hex.EncodeHexString(HashValue));
 178             if (m_hashAlg != null)
 179                 root.AddAttribute(s_tagHashAlgorithm, HashAlgorithm.GetType().FullName);
 180             return root;
 181         }
 182
 183         public void FromXml(SecurityElement e, PolicyLevel level) {
 184             if (e == null)
 185                 throw new ArgumentNullException("e");
 186
 187             if (!e.Tag.Equals("IMembershipCondition"))
 188                 throw new ArgumentException(Environment.GetResourceString("Argument_MembershipConditionElement"));
 189             Contract.EndContractBlock();
 190
 191             lock (InternalSyncObject) {
 192                 m_element = e;
 193                 m_value = null;
 194                 m_hashAlg = null;
 195             }
 196         }
 197
 198         public override bool Equals(Object o) {
 199             HashMembershipCondition that = (o as HashMembershipCondition);
 200             if (that != null) {
 201                 if (this.m_hashAlg == null && this.m_element != null)
 202                     this.ParseHashAlgorithm();
 203                 if (that.m_hashAlg == null && that.m_element != null)
 204                     that.ParseHashAlgorithm();
 205
 206                 if (this.m_hashAlg != null && that.m_hashAlg != null &&
 207                     this.m_hashAlg.GetType() == that.m_hashAlg.GetType()) {
 208                     if (this.m_value == null && this.m_element != null)
 209                         this.ParseHashValue();
 210                     if (that.m_value == null && that.m_element != null)
 211                         that.ParseHashValue();
 212
 213                     if (this.m_value.Length != that.m_value.Length)
 214                         return false;
 215
 216                     for (int i = 0; i < m_value.Length; i++) {
 217                         if (this.m_value[i] != that.m_value[i])
 218                             return false;
 219                     }
 220                     return true;
 221                 }
 222             }
 223             return false;
 224         }
 225
 226         public override int GetHashCode() {
 227             if (this.m_hashAlg == null && this.m_element != null)
 228                 this.ParseHashAlgorithm();
 229
 230             int accumulator = this.m_hashAlg != null ? this.m_hashAlg.GetType().GetHashCode() : 0;
 231             if (this.m_value == null && this.m_element != null)
 232                 this.ParseHashValue();
 233
 234             accumulator = accumulator ^ GetByteArrayHashCode(this.m_value);
 235             return accumulator;
 236         }
 237
 238         public override string ToString() {
 239             if (m_hashAlg == null)
 240                 ParseHashAlgorithm();
 241
 242             return Environment.GetResourceString("Hash_ToString", m_hashAlg.GetType().AssemblyQualifiedName, Hex.EncodeHexString(HashValue));
 243         }
 244
 245         private const string s_tagHashValue = "HashValue";
 246         private const string s_tagHashAlgorithm = "HashAlgorithm";
 247
 248         private void ParseHashValue() {
 249             lock (InternalSyncObject) {
 250                 if (m_element == null)
 251                     return;
 252
 253                 string elHash = m_element.Attribute(s_tagHashValue);
 254                 if (elHash != null)
 255                     m_value = Hex.DecodeHexString(elHash);
 256                 else
 257                     throw new ArgumentException(Environment.GetResourceString("Argument_InvalidXMLElement", s_tagHashValue, this.GetType().FullName));
 258
 259                 if (m_value != null && m_hashAlg != null) {
 260                     m_element = null;
 261                 }
 262             }
 263         }
 264
 265         private void ParseHashAlgorithm() {
 266             lock (InternalSyncObject) {
 267                 if (m_element == null)
 268                     return;
 269
 270                 string elHashAlg = m_element.Attribute(s_tagHashAlgorithm);
 271                 if (elHashAlg != null)
 272                     m_hashAlg = HashAlgorithm.Create(elHashAlg);
 273                 else
 274                     m_hashAlg = new SHA1Managed();
 275
 276                 if (m_value != null && m_hashAlg != null)
 277                     m_element = null;
 278             }
 279         }
 280
 281         private static bool CompareArrays(byte[] first, byte[] second) {
 282             if (first.Length != second.Length)
 283                 return false;
 284
 285             int count = first.Length;
 286             for (int i = 0; i < count; ++i) {
 287                 if (first[i] != second[i])
 288                     return false;
 289             }
 290
 291             return true;
 292         }
 293
 294         private static int GetByteArrayHashCode(byte[] baData) {
 295             if (baData == null)
 296                 return 0;
 297
 298             int accumulator = 0;
 299             for (int i = 0; i < baData.Length; ++i) {
 300                 accumulator = (accumulator << 8) ^ (int)baData[i] ^ (accumulator >> 24);
 301             }
 302             return accumulator;
 303         }
 304     }
 305 }