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 using XX509Chain = PrebuiltSystem::System.Security.Cryptography.X509Certificates.X509Chain;
  22 #else
  23 using XX509CertificateCollection = System.Security.Cryptography.X509Certificates.X509CertificateCollection;
  24 using XX509Chain = System.Security.Cryptography.X509Certificates.X509Chain;
  25 #endif
  26
  27 using System;
  28 using System.Net;
  29 using System.Threading;
  30 using System.Collections;
  31 using System.Collections.Generic;
  32 using System.Collections.Specialized;
  33 using System.Configuration;
  34 using System.Net.Configuration;
  35 using System.Text.RegularExpressions;
  36 using System.Security.Cryptography.X509Certificates;
  37
  38 using System.Globalization;
  39 using System.Net.Security;
  40 using System.Diagnostics;
  41
  42 namespace Mono.Net.Security
  43 {
  44         internal static class SystemCertificateValidator
  45         {
  46                 static bool is_macosx;
  47                 static bool is_mobile;
  48 #if !MOBILE
  49                 static X509RevocationMode revocation_mode;
  50 #endif
  51
  52                 static SystemCertificateValidator ()
  53                 {
  54 #if MONOTOUCH
  55                         is_macosx = true;
  56                         is_mobile = true;
  57 #elif MONODROID
  58                         is_macosx = false;
  59                         is_mobile = true;
  60 #else
  61                         is_macosx = System.IO.File.Exists (OSX509Certificates.SecurityLibrary);
  62                         is_mobile = false;
  63 #endif
  64
  65 #if !MOBILE
  66                         revocation_mode = X509RevocationMode.NoCheck;
  67                         try {
  68                                 string str = Environment.GetEnvironmentVariable ("MONO_X509_REVOCATION_MODE");
  69                                 if (String.IsNullOrEmpty (str))
  70                                         return;
  71                                 revocation_mode = (X509RevocationMode)Enum.Parse (typeof(X509RevocationMode), str, true);
  72                         } catch {
  73                         }
  74 #endif
  75                 }
  76
  77                 public static X509Chain CreateX509Chain (XX509CertificateCollection certs)
  78                 {
  79                         var chain = new X509Chain ();
  80                         chain.ChainPolicy = new X509ChainPolicy ();
  81
  82 #if !MOBILE
  83                         chain.ChainPolicy.RevocationMode = revocation_mode;
  84 #endif
  85
  86                         for (int i = 1; i < certs.Count; i++) {
  87                                 chain.ChainPolicy.ExtraStore.Add (certs [i]);
  88                         }
  89
  90                         return chain;
  91                 }
  92
  93                 public static bool BuildX509Chain (XX509CertificateCollection certs, X509Chain chain, ref SslPolicyErrors errors, ref int status11)
  94                 {
  95 #if MOBILE
  96                         return true;
  97 #else
  98                         if (is_macosx)
  99                                 return true;
 100
 101                         var leaf = (X509Certificate2)certs [0];
 102
 103                         bool ok;
 104                         try {
 105                                 ok = chain.Build (leaf);
 106                                 if (!ok)
 107                                         errors |= GetErrorsFromChain (chain);
 108                         } catch (Exception e) {
 109                                 Console.Error.WriteLine ("ERROR building certificate chain: {0}", e);
 110                                 Console.Error.WriteLine ("Please, report this problem to the Mono team");
 111                                 errors |= SslPolicyErrors.RemoteCertificateChainErrors;
 112                         }
 113
 114                         try {
 115                                 status11 = GetStatusFromChain (chain);
 116                         } catch {
 117                                 status11 = 0x800B010B; // TRUST_E_FAIL - generic
 118                         }
 119
 120                         return chain;
 121 #endif
 122                 }
 123
 124                 static bool CheckUsage (XX509CertificateCollection certs, string host, ref SslPolicyErrors errors, ref int status11)
 125                 {
 126 #if !MONOTOUCH
 127                         var leaf = (X509Certificate2)certs[0];
 128                         // for OSX and iOS we're using the native API to check for the SSL server policy and host names
 129                         if (!is_macosx) {
 130                                 if (!CheckCertificateUsage (leaf)) {
 131                                         errors |= SslPolicyErrors.RemoteCertificateChainErrors;
 132                                         status11 = -2146762490; //CERT_E_PURPOSE 0x800B0106
 133                                         return false;
 134                                 }
 135
 136                                 if (host != null && !CheckServerIdentity (leaf, host)) {
 137                                         errors |= SslPolicyErrors.RemoteCertificateNameMismatch;
 138                                         status11 = -2146762481; // CERT_E_CN_NO_MATCH 0x800B010F
 139                                         return false;
 140                                 }
 141                         }
 142 #endif
 143                         return true;
 144                 }
 145
 146                 static bool EvaluateSystem (XX509CertificateCollection certs, XX509CertificateCollection anchors, string host, X509Chain chain, ref SslPolicyErrors errors, ref int status11)
 147                 {
 148                         var leaf = certs [0];
 149                         var result = false;
 150
 151 #if MONODROID
 152                         result = AndroidPlatform.TrustEvaluateSsl (certs);
 153                         if (result) {
 154                                 // chain.Build() + GetErrorsFromChain() (above) will ALWAYS fail on
 155                                 // Android (there are no mozroots or preinstalled root certificates),
 156                                 // thus `errors` will ALWAYS have RemoteCertificateChainErrors.
 157                                 // Android just verified the chain; clear RemoteCertificateChainErrors.
 158                                 errors  &= ~SslPolicyErrors.RemoteCertificateChainErrors;
 159                         }
 160 #else
 161                         if (is_macosx) {
 162                                 // Attempt to use OSX certificates
 163                                 // Ideally we should return the SecTrustResult
 164                                 OSX509Certificates.SecTrustResult trustResult = OSX509Certificates.SecTrustResult.Deny;
 165                                 try {
 166                                         trustResult = OSX509Certificates.TrustEvaluateSsl (certs, anchors, host);
 167                                         // We could use the other values of trustResult to pass this extra information
 168                                         // to the .NET 2 callback for values like SecTrustResult.Confirm
 169                                         result = (trustResult == OSX509Certificates.SecTrustResult.Proceed ||
 170                                                 trustResult == OSX509Certificates.SecTrustResult.Unspecified);
 171                                 } catch {
 172                                         // Ignore
 173                                 }
 174
 175                                 if (result) {
 176                                         // TrustEvaluateSsl was successful so there's no trust error
 177                                         // IOW we discard our own chain (since we trust OSX one instead)
 178                                         errors = 0;
 179                                 } else {
 180                                         // callback and DefaultCertificatePolicy needs this since 'result' is not specified
 181                                         status11 = (int)trustResult;
 182                                         errors |= SslPolicyErrors.RemoteCertificateChainErrors;
 183                                 }
 184                         }
 185 #endif
 186
 187                         return result;
 188                 }
 189
 190                 public static bool Evaluate (
 191                         MonoTlsSettings settings, string host, XX509CertificateCollection certs,
 192                         X509Chain chain, ref SslPolicyErrors errors, ref int status11)
 193                 {
 194                         if (!CheckUsage (certs, host, ref errors, ref status11))
 195                                 return false;
 196
 197                         if (settings != null && settings.SkipSystemValidators)
 198                                 return false;
 199
 200                         var anchors = settings != null ? settings.TrustAnchors : null;
 201                         return EvaluateSystem (certs, anchors, host, chain, ref errors, ref status11);
 202                 }
 203
 204                 internal static bool NeedsChain (MonoTlsSettings settings)
 205                 {
 206 #if MOBILE
 207                         return false;
 208 #else
 209                         if (!CertificateValidationHelper.SupportsX509Chain)
 210                                 return false;
 211                         if (settings != null)
 212                                 return !settings.SkipSystemValidators || settings.CallbackNeedsCertificateChain;
 213                         else
 214                                 return true;
 215 #endif
 216                 }
 217
 218 #if !MOBILE
 219                 static int GetStatusFromChain (X509Chain chain)
 220                 {
 221                         long result = 0;
 222                         foreach (var status in chain.ChainStatus) {
 223                                 X509ChainStatusFlags flags = status.Status;
 224                                 if (flags == X509ChainStatusFlags.NoError)
 225                                         continue;
 226
 227                                 // CERT_E_EXPIRED
 228                                 if ((flags & X509ChainStatusFlags.NotTimeValid) != 0)
 229                                         result = 0x800B0101;
 230                                 // CERT_E_VALIDITYPERIODNESTING
 231                                 else if ((flags & X509ChainStatusFlags.NotTimeNested) != 0)
 232                                         result = 0x800B0102;
 233                                 // CERT_E_REVOKED
 234                                 else if ((flags & X509ChainStatusFlags.Revoked) != 0)
 235                                         result = 0x800B010C;
 236                                 // TRUST_E_CERT_SIGNATURE
 237                                 else if ((flags & X509ChainStatusFlags.NotSignatureValid) != 0)
 238                                         result = 0x80096004;
 239                                 // CERT_E_WRONG_USAGE
 240                                 else if ((flags & X509ChainStatusFlags.NotValidForUsage) != 0)
 241                                         result = 0x800B0110;
 242                                 // CERT_E_UNTRUSTEDROOT
 243                                 else if ((flags & X509ChainStatusFlags.UntrustedRoot) != 0)
 244                                         result = 0x800B0109;
 245                                 // CRYPT_E_NO_REVOCATION_CHECK
 246                                 else if ((flags & X509ChainStatusFlags.RevocationStatusUnknown) != 0)
 247                                         result = 0x80092012;
 248                                 // CERT_E_CHAINING
 249                                 else if ((flags & X509ChainStatusFlags.Cyclic) != 0)
 250                                         result = 0x800B010A;
 251                                 // TRUST_E_FAIL - generic
 252                                 else if ((flags & X509ChainStatusFlags.InvalidExtension) != 0)
 253                                         result = 0x800B010B;
 254                                 // CERT_E_UNTRUSTEDROOT
 255                                 else if ((flags & X509ChainStatusFlags.InvalidPolicyConstraints) != 0)
 256                                         result = 0x800B010D;
 257                                 // TRUST_E_BASIC_CONSTRAINTS
 258                                 else if ((flags & X509ChainStatusFlags.InvalidBasicConstraints) != 0)
 259                                         result = 0x80096019;
 260                                 // CERT_E_INVALID_NAME
 261                                 else if ((flags & X509ChainStatusFlags.InvalidNameConstraints) != 0)
 262                                         result = 0x800B0114;
 263                                 // CERT_E_INVALID_NAME
 264                                 else if ((flags & X509ChainStatusFlags.HasNotSupportedNameConstraint) != 0)
 265                                         result = 0x800B0114;
 266                                 // CERT_E_INVALID_NAME
 267                                 else if ((flags & X509ChainStatusFlags.HasNotDefinedNameConstraint) != 0)
 268                                         result = 0x800B0114;
 269                                 // CERT_E_INVALID_NAME
 270                                 else if ((flags & X509ChainStatusFlags.HasNotPermittedNameConstraint) != 0)
 271                                         result = 0x800B0114;
 272                                 // CERT_E_INVALID_NAME
 273                                 else if ((flags & X509ChainStatusFlags.HasExcludedNameConstraint) != 0)
 274                                         result = 0x800B0114;
 275                                 // CERT_E_CHAINING
 276                                 else if ((flags & X509ChainStatusFlags.PartialChain) != 0)
 277                                         result = 0x800B010A;
 278                                 // CERT_E_EXPIRED
 279                                 else if ((flags & X509ChainStatusFlags.CtlNotTimeValid) != 0)
 280                                         result = 0x800B0101;
 281                                 // TRUST_E_CERT_SIGNATURE
 282                                 else if ((flags & X509ChainStatusFlags.CtlNotSignatureValid) != 0)
 283                                         result = 0x80096004;
 284                                 // CERT_E_WRONG_USAGE
 285                                 else if ((flags & X509ChainStatusFlags.CtlNotValidForUsage) != 0)
 286                                         result = 0x800B0110;
 287                                 // CRYPT_E_NO_REVOCATION_CHECK
 288                                 else if ((flags & X509ChainStatusFlags.OfflineRevocation) != 0)
 289                                         result = 0x80092012;
 290                                 // CERT_E_ISSUERCHAINING
 291                                 else if ((flags & X509ChainStatusFlags.NoIssuanceChainPolicy) != 0)
 292                                         result = 0x800B0107;
 293                                 else
 294                                         result = 0x800B010B; // TRUST_E_FAIL - generic
 295
 296                                 break; // Exit the loop on the first error
 297                         }
 298                         return (int)result;
 299                 }
 300
 301                 static SslPolicyErrors GetErrorsFromChain (X509Chain chain)
 302                 {
 303                         SslPolicyErrors errors = SslPolicyErrors.None;
 304                         foreach (var status in chain.ChainStatus) {
 305                                 if (status.Status == X509ChainStatusFlags.NoError)
 306                                         continue;
 307                                 errors |= SslPolicyErrors.RemoteCertificateChainErrors;
 308                                 break;
 309                         }
 310                         return errors;
 311                 }
 312 #endif
 313
 314 #if !MONOTOUCH
 315                 static X509KeyUsageFlags s_flags = X509KeyUsageFlags.DigitalSignature |
 316                         X509KeyUsageFlags.KeyAgreement |
 317                         X509KeyUsageFlags.KeyEncipherment;
 318                 // Adapted to System 2.0+ from TlsServerCertificate.cs
 319                 //------------------------------
 320                 // Note: this method only works for RSA certificates
 321                 // DH certificates requires some changes - does anyone use one ?
 322                 static bool CheckCertificateUsage (X509Certificate2 cert)
 323                 {
 324                         try {
 325                                 // certificate extensions are required for this
 326                                 // we "must" accept older certificates without proofs
 327                                 if (cert.Version < 3)
 328                                         return true;
 329
 330                                 X509KeyUsageExtension kux = (cert.Extensions ["2.5.29.15"] as X509KeyUsageExtension);
 331                                 X509EnhancedKeyUsageExtension eku = (cert.Extensions ["2.5.29.37"] as X509EnhancedKeyUsageExtension);
 332                                 if (kux != null && eku != null) {
 333                                         // RFC3280 states that when both KeyUsageExtension and
 334                                         // ExtendedKeyUsageExtension are present then BOTH should
 335                                         // be valid
 336                                         if ((kux.KeyUsages & s_flags) == 0)
 337                                                 return false;
 338                                         return eku.EnhancedKeyUsages ["1.3.6.1.5.5.7.3.1"] != null ||
 339                                                 eku.EnhancedKeyUsages ["2.16.840.1.113730.4.1"] != null;
 340                                 } else if (kux != null) {
 341                                         return ((kux.KeyUsages & s_flags) != 0);
 342                                 } else if (eku != null) {
 343                                         // Server Authentication (1.3.6.1.5.5.7.3.1) or
 344                                         // Netscape Server Gated Crypto (2.16.840.1.113730.4)
 345                                         return eku.EnhancedKeyUsages ["1.3.6.1.5.5.7.3.1"] != null ||
 346                                                 eku.EnhancedKeyUsages ["2.16.840.1.113730.4.1"] != null;
 347                                 }
 348
 349                                 // last chance - try with older (deprecated) Netscape extensions
 350                                 X509Extension ext = cert.Extensions ["2.16.840.1.113730.1.1"];
 351                                 if (ext != null) {
 352                                         string text = ext.NetscapeCertType (false);
 353                                         return text.IndexOf ("SSL Server Authentication", StringComparison.Ordinal) != -1;
 354                                 }
 355                                 return true;
 356                         } catch (Exception e) {
 357                                 Console.Error.WriteLine ("ERROR processing certificate: {0}", e);
 358                                 Console.Error.WriteLine ("Please, report this problem to the Mono team");
 359                                 return false;
 360                         }
 361                 }
 362
 363                 // RFC2818 - HTTP Over TLS, Section 3.1
 364                 // http://www.ietf.org/rfc/rfc2818.txt
 365                 //
 366                 // 1.   if present MUST use subjectAltName dNSName as identity
 367                 // 1.1.         if multiples entries a match of any one is acceptable
 368                 // 1.2.         wildcard * is acceptable
 369                 // 2.   URI may be an IP address -> subjectAltName.iPAddress
 370                 // 2.1.         exact match is required
 371                 // 3.   Use of the most specific Common Name (CN=) in the Subject
 372                 // 3.1          Existing practice but DEPRECATED
 373                 static bool CheckServerIdentity (X509Certificate2 cert, string targetHost)
 374                 {
 375                         try {
 376                                 var mcert = new MSX.X509Certificate (cert.RawData);
 377                                 MSX.X509Extension ext = mcert.Extensions ["2.5.29.17"];
 378                                 // 1. subjectAltName
 379                                 if (ext != null) {
 380                                         SubjectAltNameExtension subjectAltName = new SubjectAltNameExtension (ext);
 381                                         // 1.1 - multiple dNSName
 382                                         foreach (string dns in subjectAltName.DNSNames) {
 383                                                 // 1.2 TODO - wildcard support
 384                                                 if (Match (targetHost, dns))
 385                                                         return true;
 386                                         }
 387                                         // 2. ipAddress
 388                                         foreach (string ip in subjectAltName.IPAddresses) {
 389                                                 // 2.1. Exact match required
 390                                                 if (ip == targetHost)
 391                                                         return true;
 392                                         }
 393                                 }
 394                                 // 3. Common Name (CN=)
 395                                 return CheckDomainName (mcert.SubjectName, targetHost);
 396                         } catch (Exception e) {
 397                                 Console.Error.WriteLine ("ERROR processing certificate: {0}", e);
 398                                 Console.Error.WriteLine ("Please, report this problem to the Mono team");
 399                                 return false;
 400                         }
 401                 }
 402
 403                 static bool CheckDomainName (string subjectName, string targetHost)
 404                 {
 405                         string  domainName = String.Empty;
 406                         Regex search = new Regex (@"CN\s*=\s*([^,]*)");
 407                         MatchCollection elements = search.Matches (subjectName);
 408                         if (elements.Count == 1) {
 409                                 if (elements [0].Success)
 410                                         domainName = elements [0].Groups [1].Value.ToString ();
 411                         }
 412
 413                         return Match (targetHost, domainName);
 414                 }
 415
 416                 // ensure the pattern is valid wrt to RFC2595 and RFC2818
 417                 // http://www.ietf.org/rfc/rfc2595.txt
 418                 // http://www.ietf.org/rfc/rfc2818.txt
 419                 static bool Match (string hostname, string pattern)
 420                 {
 421                         // check if this is a pattern
 422                         int index = pattern.IndexOf ('*');
 423                         if (index == -1) {
 424                                 // not a pattern, do a direct case-insensitive comparison
 425                                 return (String.Compare (hostname, pattern, true, CultureInfo.InvariantCulture) == 0);
 426                         }
 427
 428                         // check pattern validity
 429                         // A "*" wildcard character MAY be used as the left-most name component in the certificate.
 430
 431                         // unless this is the last char (valid)
 432                         if (index != pattern.Length - 1) {
 433                                 // then the next char must be a dot .'.
 434                                 if (pattern [index + 1] != '.')
 435                                         return false;
 436                         }
 437
 438                         // only one (A) wildcard is supported
 439                         int i2 = pattern.IndexOf ('*', index + 1);
 440                         if (i2 != -1)
 441                                 return false;
 442
 443                         // match the end of the pattern
 444                         string end = pattern.Substring (index + 1);
 445                         int length = hostname.Length - end.Length;
 446                         // no point to check a pattern that is longer than the hostname
 447                         if (length <= 0)
 448                                 return false;
 449
 450                         if (String.Compare (hostname, length, end, 0, end.Length, true, CultureInfo.InvariantCulture) != 0)
 451                                 return false;
 452
 453                         // special case, we start with the wildcard
 454                         if (index == 0) {
 455                                 // ensure we hostname non-matched part (start) doesn't contain a dot
 456                                 int i3 = hostname.IndexOf ('.');
 457                                 return ((i3 == -1) || (i3 >= (hostname.Length - end.Length)));
 458                         }
 459
 460                         // match the start of the pattern
 461                         string start = pattern.Substring (0, index);
 462                         return (String.Compare (hostname, 0, start, 0, start.Length, true, CultureInfo.InvariantCulture) == 0);
 463                 }
 464 #endif
 465         }
 466 }
 467 #endif
 468