mcs/class/System/Mono.Net.Security/SystemCertificateValidator.cs

   1 #if SECURITY_DEP
   2
   3 #if MONO_SECURITY_ALIAS
   4 extern alias MonoSecurity;
   5 #endif
   6 #if MONO_X509_ALIAS
   7 extern alias PrebuiltSystem;
   8 #endif
   9
  10 #if MONO_SECURITY_ALIAS
  11 using MonoSecurity::Mono.Security.Interface;
  12 using MSX = MonoSecurity::Mono.Security.X509;
  13 using MonoSecurity::Mono.Security.X509.Extensions;
  14 #else
  15 using Mono.Security.Interface;
  16 using MSX = Mono.Security.X509;
  17 using Mono.Security.X509.Extensions;
  18 #endif
  19 #if MONO_X509_ALIAS
  20 using XX509CertificateCollection = PrebuiltSystem::System.Security.Cryptography.X509Certificates.X509CertificateCollection;
  21 #else
  22 using XX509CertificateCollection = System.Security.Cryptography.X509Certificates.X509CertificateCollection;
  23 #endif
  24
  25 using System;
  26 using System.Net;
  27 using System.Threading;
  28 using System.Collections;
  29 using System.Collections.Generic;
  30 using System.Collections.Specialized;
  31 using System.Configuration;
  32 using System.Net.Configuration;
  33 using System.Text.RegularExpressions;
  34 using System.Security.Cryptography.X509Certificates;
  35
  36 using System.Globalization;
  37 using System.Net.Security;
  38 using System.Diagnostics;
  39
  40 namespace Mono.Net.Security
  41 {
  42         internal static class SystemCertificateValidator
  43         {
  44                 static bool is_macosx;
  45                 static bool is_mobile;
  46 #if !MOBILE
  47                 static X509RevocationMode revocation_mode;
  48 #endif
  49
  50                 static SystemCertificateValidator ()
  51                 {
  52 #if MONOTOUCH
  53                         is_macosx = true;
  54                         is_mobile = true;
  55 #elif MONODROID
  56                         is_macosx = false;
  57                         is_mobile = true;
  58 #else
  59                         is_macosx = System.IO.File.Exists (OSX509Certificates.SecurityLibrary);
  60                         is_mobile = false;
  61 #endif
  62
  63 #if !MOBILE
  64                         revocation_mode = X509RevocationMode.NoCheck;
  65                         try {
  66                                 string str = Environment.GetEnvironmentVariable ("MONO_X509_REVOCATION_MODE");
  67                                 if (String.IsNullOrEmpty (str))
  68                                         return;
  69                                 revocation_mode = (X509RevocationMode)Enum.Parse (typeof(X509RevocationMode), str, true);
  70                         } catch {
  71                         }
  72 #endif
  73                 }
  74
  75                 static X509Chain ComputeX509Chain (XX509CertificateCollection certs, ref SslPolicyErrors errors, ref int status11)
  76                 {
  77 #if MOBILE
  78                         return null;
  79 #else
  80                         if (is_macosx)
  81                                 return null;
  82
  83                         var chain = new X509Chain ();
  84                         chain.ChainPolicy = new X509ChainPolicy ();
  85
  86                         chain.ChainPolicy.RevocationMode = revocation_mode;
  87
  88                         for (int i = 1; i < certs.Count; i++) {
  89                                 chain.ChainPolicy.ExtraStore.Add (certs [i]);
  90                         }
  91
  92                         var leaf = (X509Certificate2)certs [0];
  93
  94                         try {
  95                                 if (!chain.Build (leaf))
  96                                         errors |= GetErrorsFromChain (chain);
  97                         } catch (Exception e) {
  98                                 Console.Error.WriteLine ("ERROR building certificate chain: {0}", e);
  99                                 Console.Error.WriteLine ("Please, report this problem to the Mono team");
 100                                 errors |= SslPolicyErrors.RemoteCertificateChainErrors;
 101                         }
 102
 103                         status11 = GetStatusFromChain (chain);
 104
 105                         return chain;
 106 #endif
 107                 }
 108
 109                 static void CheckUsage (XX509CertificateCollection certs, string host, ref SslPolicyErrors errors, ref int status11)
 110                 {
 111 #if !MONOTOUCH
 112                         var leaf = (X509Certificate2)certs[0];
 113                         // for OSX and iOS we're using the native API to check for the SSL server policy and host names
 114                         if (!is_macosx) {
 115                                 if (!CheckCertificateUsage (leaf)) {
 116                                         errors |= SslPolicyErrors.RemoteCertificateChainErrors;
 117                                         status11 = -2146762490; //CERT_E_PURPOSE 0x800B0106
 118                                 }
 119
 120                                 if (host != null && !CheckServerIdentity (leaf, host)) {
 121                                         errors |= SslPolicyErrors.RemoteCertificateNameMismatch;
 122                                         status11 = -2146762481; // CERT_E_CN_NO_MATCH 0x800B010F
 123                                 }
 124                         }
 125 #endif
 126                 }
 127
 128                 static bool EvaluateSystem (XX509CertificateCollection certs, XX509CertificateCollection anchors, string host, X509Chain chain, ref SslPolicyErrors errors, ref int status11)
 129                 {
 130                         var leaf = certs [0];
 131                         var result = false;
 132
 133 #if MONODROID
 134                         result = AndroidPlatform.TrustEvaluateSsl (certs);
 135                         if (result) {
 136                                 // chain.Build() + GetErrorsFromChain() (above) will ALWAYS fail on
 137                                 // Android (there are no mozroots or preinstalled root certificates),
 138                                 // thus `errors` will ALWAYS have RemoteCertificateChainErrors.
 139                                 // Android just verified the chain; clear RemoteCertificateChainErrors.
 140                                 errors  &= ~SslPolicyErrors.RemoteCertificateChainErrors;
 141                         }
 142 #else
 143                         if (is_macosx) {
 144                                 // Attempt to use OSX certificates
 145                                 // Ideally we should return the SecTrustResult
 146                                 OSX509Certificates.SecTrustResult trustResult = OSX509Certificates.SecTrustResult.Deny;
 147                                 try {
 148                                         trustResult = OSX509Certificates.TrustEvaluateSsl (certs, anchors, host);
 149                                         // We could use the other values of trustResult to pass this extra information
 150                                         // to the .NET 2 callback for values like SecTrustResult.Confirm
 151                                         result = (trustResult == OSX509Certificates.SecTrustResult.Proceed ||
 152                                                 trustResult == OSX509Certificates.SecTrustResult.Unspecified);
 153                                 } catch {
 154                                         // Ignore
 155                                 }
 156
 157                                 if (result) {
 158                                         // TrustEvaluateSsl was successful so there's no trust error
 159                                         // IOW we discard our own chain (since we trust OSX one instead)
 160                                         errors = 0;
 161                                 } else {
 162                                         // callback and DefaultCertificatePolicy needs this since 'result' is not specified
 163                                         status11 = (int)trustResult;
 164                                         errors |= SslPolicyErrors.RemoteCertificateChainErrors;
 165                                 }
 166                         }
 167 #endif
 168
 169                         return result;
 170                 }
 171
 172                 public static bool Evaluate (
 173                         MonoTlsSettings settings, string host, XX509CertificateCollection certs,
 174                         ref X509Chain chain, ref SslPolicyErrors errors, ref int status11)
 175                 {
 176 #if !MOBILE
 177                         if (NeedsChain (settings) && chain == null)
 178                                 chain = ComputeX509Chain (certs, ref errors, ref status11);
 179 #endif
 180
 181                         CheckUsage (certs, host, ref errors, ref status11);
 182
 183                         if (settings != null && settings.SkipSystemValidators)
 184                                 return false;
 185
 186                         var anchors = settings != null ? settings.TrustAnchors : null;
 187                         return EvaluateSystem (certs, anchors, host, chain, ref errors, ref status11);
 188                 }
 189
 190                 internal static bool NeedsChain (MonoTlsSettings settings)
 191                 {
 192 #if MOBILE
 193                         return false;
 194 #else
 195                         if (!CertificateValidationHelper.SupportsX509Chain)
 196                                 return false;
 197                         if (settings != null)
 198                                 return !settings.SkipSystemValidators || settings.CallbackNeedsCertificateChain;
 199                         else
 200                                 return true;
 201 #endif
 202                 }
 203
 204 #if !MOBILE
 205                 static int GetStatusFromChain (X509Chain chain)
 206                 {
 207                         long result = 0;
 208                         foreach (var status in chain.ChainStatus) {
 209                                 X509ChainStatusFlags flags = status.Status;
 210                                 if (flags == X509ChainStatusFlags.NoError)
 211                                         continue;
 212
 213                                 // CERT_E_EXPIRED
 214                                 if ((flags & X509ChainStatusFlags.NotTimeValid) != 0)
 215                                         result = 0x800B0101;
 216                                 // CERT_E_VALIDITYPERIODNESTING
 217                                 else if ((flags & X509ChainStatusFlags.NotTimeNested) != 0)
 218                                         result = 0x800B0102;
 219                                 // CERT_E_REVOKED
 220                                 else if ((flags & X509ChainStatusFlags.Revoked) != 0)
 221                                         result = 0x800B010C;
 222                                 // TRUST_E_CERT_SIGNATURE
 223                                 else if ((flags & X509ChainStatusFlags.NotSignatureValid) != 0)
 224                                         result = 0x80096004;
 225                                 // CERT_E_WRONG_USAGE
 226                                 else if ((flags & X509ChainStatusFlags.NotValidForUsage) != 0)
 227                                         result = 0x800B0110;
 228                                 // CERT_E_UNTRUSTEDROOT
 229                                 else if ((flags & X509ChainStatusFlags.UntrustedRoot) != 0)
 230                                         result = 0x800B0109;
 231                                 // CRYPT_E_NO_REVOCATION_CHECK
 232                                 else if ((flags & X509ChainStatusFlags.RevocationStatusUnknown) != 0)
 233                                         result = 0x80092012;
 234                                 // CERT_E_CHAINING
 235                                 else if ((flags & X509ChainStatusFlags.Cyclic) != 0)
 236                                         result = 0x800B010A;
 237                                 // TRUST_E_FAIL - generic
 238                                 else if ((flags & X509ChainStatusFlags.InvalidExtension) != 0)
 239                                         result = 0x800B010B;
 240                                 // CERT_E_UNTRUSTEDROOT
 241                                 else if ((flags & X509ChainStatusFlags.InvalidPolicyConstraints) != 0)
 242                                         result = 0x800B010D;
 243                                 // TRUST_E_BASIC_CONSTRAINTS
 244                                 else if ((flags & X509ChainStatusFlags.InvalidBasicConstraints) != 0)
 245                                         result = 0x80096019;
 246                                 // CERT_E_INVALID_NAME
 247                                 else if ((flags & X509ChainStatusFlags.InvalidNameConstraints) != 0)
 248                                         result = 0x800B0114;
 249                                 // CERT_E_INVALID_NAME
 250                                 else if ((flags & X509ChainStatusFlags.HasNotSupportedNameConstraint) != 0)
 251                                         result = 0x800B0114;
 252                                 // CERT_E_INVALID_NAME
 253                                 else if ((flags & X509ChainStatusFlags.HasNotDefinedNameConstraint) != 0)
 254                                         result = 0x800B0114;
 255                                 // CERT_E_INVALID_NAME
 256                                 else if ((flags & X509ChainStatusFlags.HasNotPermittedNameConstraint) != 0)
 257                                         result = 0x800B0114;
 258                                 // CERT_E_INVALID_NAME
 259                                 else if ((flags & X509ChainStatusFlags.HasExcludedNameConstraint) != 0)
 260                                         result = 0x800B0114;
 261                                 // CERT_E_CHAINING
 262                                 else if ((flags & X509ChainStatusFlags.PartialChain) != 0)
 263                                         result = 0x800B010A;
 264                                 // CERT_E_EXPIRED
 265                                 else if ((flags & X509ChainStatusFlags.CtlNotTimeValid) != 0)
 266                                         result = 0x800B0101;
 267                                 // TRUST_E_CERT_SIGNATURE
 268                                 else if ((flags & X509ChainStatusFlags.CtlNotSignatureValid) != 0)
 269                                         result = 0x80096004;
 270                                 // CERT_E_WRONG_USAGE
 271                                 else if ((flags & X509ChainStatusFlags.CtlNotValidForUsage) != 0)
 272                                         result = 0x800B0110;
 273                                 // CRYPT_E_NO_REVOCATION_CHECK
 274                                 else if ((flags & X509ChainStatusFlags.OfflineRevocation) != 0)
 275                                         result = 0x80092012;
 276                                 // CERT_E_ISSUERCHAINING
 277                                 else if ((flags & X509ChainStatusFlags.NoIssuanceChainPolicy) != 0)
 278                                         result = 0x800B0107;
 279                                 else
 280                                         result = 0x800B010B; // TRUST_E_FAIL - generic
 281
 282                                 break; // Exit the loop on the first error
 283                         }
 284                         return (int)result;
 285                 }
 286
 287                 static SslPolicyErrors GetErrorsFromChain (X509Chain chain)
 288                 {
 289                         SslPolicyErrors errors = SslPolicyErrors.None;
 290                         foreach (var status in chain.ChainStatus) {
 291                                 if (status.Status == X509ChainStatusFlags.NoError)
 292                                         continue;
 293                                 errors |= SslPolicyErrors.RemoteCertificateChainErrors;
 294                                 break;
 295                         }
 296                         return errors;
 297                 }
 298 #endif
 299
 300 #if !MONOTOUCH
 301                 static X509KeyUsageFlags s_flags = X509KeyUsageFlags.DigitalSignature |
 302                         X509KeyUsageFlags.KeyAgreement |
 303                         X509KeyUsageFlags.KeyEncipherment;
 304                 // Adapted to System 2.0+ from TlsServerCertificate.cs
 305                 //------------------------------
 306                 // Note: this method only works for RSA certificates
 307                 // DH certificates requires some changes - does anyone use one ?
 308                 static bool CheckCertificateUsage (X509Certificate2 cert)
 309                 {
 310                         try {
 311                                 // certificate extensions are required for this
 312                                 // we "must" accept older certificates without proofs
 313                                 if (cert.Version < 3)
 314                                         return true;
 315
 316                                 X509KeyUsageExtension kux = (cert.Extensions ["2.5.29.15"] as X509KeyUsageExtension);
 317                                 X509EnhancedKeyUsageExtension eku = (cert.Extensions ["2.5.29.37"] as X509EnhancedKeyUsageExtension);
 318                                 if (kux != null && eku != null) {
 319                                         // RFC3280 states that when both KeyUsageExtension and
 320                                         // ExtendedKeyUsageExtension are present then BOTH should
 321                                         // be valid
 322                                         if ((kux.KeyUsages & s_flags) == 0)
 323                                                 return false;
 324                                         return eku.EnhancedKeyUsages ["1.3.6.1.5.5.7.3.1"] != null ||
 325                                                 eku.EnhancedKeyUsages ["2.16.840.1.113730.4.1"] != null;
 326                                 } else if (kux != null) {
 327                                         return ((kux.KeyUsages & s_flags) != 0);
 328                                 } else if (eku != null) {
 329                                         // Server Authentication (1.3.6.1.5.5.7.3.1) or
 330                                         // Netscape Server Gated Crypto (2.16.840.1.113730.4)
 331                                         return eku.EnhancedKeyUsages ["1.3.6.1.5.5.7.3.1"] != null ||
 332                                                 eku.EnhancedKeyUsages ["2.16.840.1.113730.4.1"] != null;
 333                                 }
 334
 335                                 // last chance - try with older (deprecated) Netscape extensions
 336                                 X509Extension ext = cert.Extensions ["2.16.840.1.113730.1.1"];
 337                                 if (ext != null) {
 338                                         string text = ext.NetscapeCertType (false);
 339                                         return text.IndexOf ("SSL Server Authentication", StringComparison.Ordinal) != -1;
 340                                 }
 341                                 return true;
 342                         } catch (Exception e) {
 343                                 Console.Error.WriteLine ("ERROR processing certificate: {0}", e);
 344                                 Console.Error.WriteLine ("Please, report this problem to the Mono team");
 345                                 return false;
 346                         }
 347                 }
 348
 349                 // RFC2818 - HTTP Over TLS, Section 3.1
 350                 // http://www.ietf.org/rfc/rfc2818.txt
 351                 //
 352                 // 1.   if present MUST use subjectAltName dNSName as identity
 353                 // 1.1.         if multiples entries a match of any one is acceptable
 354                 // 1.2.         wildcard * is acceptable
 355                 // 2.   URI may be an IP address -> subjectAltName.iPAddress
 356                 // 2.1.         exact match is required
 357                 // 3.   Use of the most specific Common Name (CN=) in the Subject
 358                 // 3.1          Existing practice but DEPRECATED
 359                 static bool CheckServerIdentity (X509Certificate2 cert, string targetHost)
 360                 {
 361                         try {
 362                                 var mcert = new MSX.X509Certificate (cert.RawData);
 363                                 MSX.X509Extension ext = mcert.Extensions ["2.5.29.17"];
 364                                 // 1. subjectAltName
 365                                 if (ext != null) {
 366                                         SubjectAltNameExtension subjectAltName = new SubjectAltNameExtension (ext);
 367                                         // 1.1 - multiple dNSName
 368                                         foreach (string dns in subjectAltName.DNSNames) {
 369                                                 // 1.2 TODO - wildcard support
 370                                                 if (Match (targetHost, dns))
 371                                                         return true;
 372                                         }
 373                                         // 2. ipAddress
 374                                         foreach (string ip in subjectAltName.IPAddresses) {
 375                                                 // 2.1. Exact match required
 376                                                 if (ip == targetHost)
 377                                                         return true;
 378                                         }
 379                                 }
 380                                 // 3. Common Name (CN=)
 381                                 return CheckDomainName (mcert.SubjectName, targetHost);
 382                         } catch (Exception e) {
 383                                 Console.Error.WriteLine ("ERROR processing certificate: {0}", e);
 384                                 Console.Error.WriteLine ("Please, report this problem to the Mono team");
 385                                 return false;
 386                         }
 387                 }
 388
 389                 static bool CheckDomainName (string subjectName, string targetHost)
 390                 {
 391                         string  domainName = String.Empty;
 392                         Regex search = new Regex (@"CN\s*=\s*([^,]*)");
 393                         MatchCollection elements = search.Matches (subjectName);
 394                         if (elements.Count == 1) {
 395                                 if (elements [0].Success)
 396                                         domainName = elements [0].Groups [1].Value.ToString ();
 397                         }
 398
 399                         return Match (targetHost, domainName);
 400                 }
 401
 402                 // ensure the pattern is valid wrt to RFC2595 and RFC2818
 403                 // http://www.ietf.org/rfc/rfc2595.txt
 404                 // http://www.ietf.org/rfc/rfc2818.txt
 405                 static bool Match (string hostname, string pattern)
 406                 {
 407                         // check if this is a pattern
 408                         int index = pattern.IndexOf ('*');
 409                         if (index == -1) {
 410                                 // not a pattern, do a direct case-insensitive comparison
 411                                 return (String.Compare (hostname, pattern, true, CultureInfo.InvariantCulture) == 0);
 412                         }
 413
 414                         // check pattern validity
 415                         // A "*" wildcard character MAY be used as the left-most name component in the certificate.
 416
 417                         // unless this is the last char (valid)
 418                         if (index != pattern.Length - 1) {
 419                                 // then the next char must be a dot .'.
 420                                 if (pattern [index + 1] != '.')
 421                                         return false;
 422                         }
 423
 424                         // only one (A) wildcard is supported
 425                         int i2 = pattern.IndexOf ('*', index + 1);
 426                         if (i2 != -1)
 427                                 return false;
 428
 429                         // match the end of the pattern
 430                         string end = pattern.Substring (index + 1);
 431                         int length = hostname.Length - end.Length;
 432                         // no point to check a pattern that is longer than the hostname
 433                         if (length <= 0)
 434                                 return false;
 435
 436                         if (String.Compare (hostname, length, end, 0, end.Length, true, CultureInfo.InvariantCulture) != 0)
 437                                 return false;
 438
 439                         // special case, we start with the wildcard
 440                         if (index == 0) {
 441                                 // ensure we hostname non-matched part (start) doesn't contain a dot
 442                                 int i3 = hostname.IndexOf ('.');
 443                                 return ((i3 == -1) || (i3 >= (hostname.Length - end.Length)));
 444                         }
 445
 446                         // match the start of the pattern
 447                         string start = pattern.Substring (0, index);
 448                         return (String.Compare (hostname, 0, start, 0, start.Length, true, CultureInfo.InvariantCulture) == 0);
 449                 }
 450 #endif
 451         }
 452 }
 453 #endif
 454