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
   7 #if MONO_SECURITY_ALIAS
   8 using MonoSecurity::Mono.Security.Interface;
   9 using MSX = MonoSecurity::Mono.Security.X509;
  10 using MonoSecurity::Mono.Security.X509.Extensions;
  11 #else
  12 using Mono.Security.Interface;
  13 using MSX = Mono.Security.X509;
  14 using Mono.Security.X509.Extensions;
  15 #endif
  16 using XX509CertificateCollection = System.Security.Cryptography.X509Certificates.X509CertificateCollection;
  17 using XX509Chain = System.Security.Cryptography.X509Certificates.X509Chain;
  18
  19 using System;
  20 using System.Net;
  21 using System.Threading;
  22 using System.Collections;
  23 using System.Collections.Generic;
  24 using System.Collections.Specialized;
  25 using System.Configuration;
  26 using System.Net.Configuration;
  27 using System.Text.RegularExpressions;
  28 using System.Security.Cryptography.X509Certificates;
  29
  30 using System.Globalization;
  31 using System.Net.Security;
  32 using System.Diagnostics;
  33
  34 namespace Mono.Net.Security
  35 {
  36         internal static class SystemCertificateValidator
  37         {
  38                 static bool is_macosx;
  39 #if !MOBILE
  40                 static X509RevocationMode revocation_mode;
  41 #endif
  42
  43                 static SystemCertificateValidator ()
  44                 {
  45 #if MONOTOUCH
  46                         is_macosx = true;
  47 #elif MONODROID
  48                         is_macosx = false;
  49 #else
  50                         is_macosx = System.IO.File.Exists (OSX509Certificates.SecurityLibrary);
  51 #endif
  52
  53 #if !MOBILE
  54                         revocation_mode = X509RevocationMode.NoCheck;
  55                         try {
  56                                 string str = Environment.GetEnvironmentVariable ("MONO_X509_REVOCATION_MODE");
  57                                 if (String.IsNullOrEmpty (str))
  58                                         return;
  59                                 revocation_mode = (X509RevocationMode)Enum.Parse (typeof(X509RevocationMode), str, true);
  60                         } catch {
  61                         }
  62 #endif
  63                 }
  64
  65                 public static X509Chain CreateX509Chain (XX509CertificateCollection certs)
  66                 {
  67                         var chain = new X509Chain ();
  68                         chain.ChainPolicy = new X509ChainPolicy ((X509CertificateCollection)(object)certs);
  69
  70 #if !MOBILE
  71                         chain.ChainPolicy.RevocationMode = revocation_mode;
  72 #endif
  73
  74                         return chain;
  75                 }
  76
  77                 static bool BuildX509Chain (XX509CertificateCollection certs, X509Chain chain, ref SslPolicyErrors errors, ref int status11)
  78                 {
  79 #if MOBILE
  80                         return false;
  81 #else
  82                         if (is_macosx)
  83                                 return false;
  84
  85                         var leaf = (X509Certificate2)certs [0];
  86
  87                         bool ok;
  88                         try {
  89                                 ok = chain.Build (leaf);
  90                                 if (!ok)
  91                                         errors |= GetErrorsFromChain (chain);
  92                         } catch (Exception e) {
  93                                 Console.Error.WriteLine ("ERROR building certificate chain: {0}", e);
  94                                 Console.Error.WriteLine ("Please, report this problem to the Mono team");
  95                                 errors |= SslPolicyErrors.RemoteCertificateChainErrors;
  96                                 ok = false;
  97                         }
  98
  99                         try {
 100                                 status11 = GetStatusFromChain (chain);
 101                         } catch {
 102                                 status11 = -2146762485; // TRUST_E_FAIL - generic
 103                         }
 104
 105                         return ok;
 106 #endif
 107                 }
 108
 109                 static bool CheckUsage (XX509CertificateCollection certs, string host, ref SslPolicyErrors errors, ref int status11)
 110                 {
 111 #if !MONOTOUCH
 112                         var leaf = certs[0] as X509Certificate2;
 113                         if (leaf == null)
 114                                 leaf = new X509Certificate2 (certs[0]);
 115                         // for OSX and iOS we're using the native API to check for the SSL server policy and host names
 116                         if (!is_macosx) {
 117                                 if (!CheckCertificateUsage (leaf)) {
 118                                         errors |= SslPolicyErrors.RemoteCertificateChainErrors;
 119                                         status11 = -2146762490; //CERT_E_PURPOSE 0x800B0106
 120                                         return false;
 121                                 }
 122
 123                                 if (!string.IsNullOrEmpty (host) && !CheckServerIdentity (leaf, host)) {
 124                                         errors |= SslPolicyErrors.RemoteCertificateNameMismatch;
 125                                         status11 = -2146762481; // CERT_E_CN_NO_MATCH 0x800B010F
 126                                         return false;
 127                                 }
 128                         }
 129 #endif
 130                         return true;
 131                 }
 132
 133                 static bool EvaluateSystem (XX509CertificateCollection certs, XX509CertificateCollection anchors, string host, X509Chain chain, ref SslPolicyErrors errors, ref int status11)
 134                 {
 135                         var leaf = certs [0];
 136                         bool result;
 137
 138 #if MONODROID
 139                         try {
 140                                 result = AndroidPlatform.TrustEvaluateSsl (certs);
 141                                 if (result) {
 142                                         // FIXME: check whether this is still correct.
 143                                         //
 144                                         // chain.Build() + GetErrorsFromChain() (above) will ALWAYS fail on
 145                                         // Android (there are no mozroots or preinstalled root certificates),
 146                                         // thus `errors` will ALWAYS have RemoteCertificateChainErrors.
 147                                         // Android just verified the chain; clear RemoteCertificateChainErrors.
 148                                         errors  &= ~SslPolicyErrors.RemoteCertificateChainErrors;
 149                                 } else {
 150                                         errors |= SslPolicyErrors.RemoteCertificateChainErrors;
 151                                         status11 = unchecked((int)0x800B010B);
 152                                 }
 153                         } catch {
 154                                 result = false;
 155                                 errors |= SslPolicyErrors.RemoteCertificateChainErrors;
 156                                 status11 = unchecked((int)0x800B010B);
 157                                 // Ignore
 158                         }
 159 #else
 160                         if (is_macosx) {
 161                                 // Attempt to use OSX certificates
 162                                 // Ideally we should return the SecTrustResult
 163                                 OSX509Certificates.SecTrustResult trustResult = OSX509Certificates.SecTrustResult.Deny;
 164                                 try {
 165                                         trustResult = OSX509Certificates.TrustEvaluateSsl (certs, anchors, host);
 166                                         // We could use the other values of trustResult to pass this extra information
 167                                         // to the .NET 2 callback for values like SecTrustResult.Confirm
 168                                         result = (trustResult == OSX509Certificates.SecTrustResult.Proceed ||
 169                                                 trustResult == OSX509Certificates.SecTrustResult.Unspecified);
 170                                 } catch {
 171                                         result = false;
 172                                         errors |= SslPolicyErrors.RemoteCertificateChainErrors;
 173                                         // Ignore
 174                                 }
 175
 176                                 if (result) {
 177                                         // TrustEvaluateSsl was successful so there's no trust error
 178                                         // IOW we discard our own chain (since we trust OSX one instead)
 179                                         errors = 0;
 180                                 } else {
 181                                         // callback and DefaultCertificatePolicy needs this since 'result' is not specified
 182                                         status11 = (int)trustResult;
 183                                         errors |= SslPolicyErrors.RemoteCertificateChainErrors;
 184                                 }
 185                         } else {
 186                                 result = BuildX509Chain (certs, chain, ref errors, ref status11);
 187                         }
 188 #endif
 189
 190                         return result;
 191                 }
 192
 193                 public static bool Evaluate (
 194                         MonoTlsSettings settings, string host, XX509CertificateCollection certs,
 195                         X509Chain chain, ref SslPolicyErrors errors, ref int status11)
 196                 {
 197                         if (!CheckUsage (certs, host, ref errors, ref status11))
 198                                 return false;
 199
 200                         if (settings != null && settings.SkipSystemValidators)
 201                                 return false;
 202
 203                         var anchors = settings != null ? settings.TrustAnchors : null;
 204                         return EvaluateSystem (certs, anchors, host, chain, ref errors, ref status11);
 205                 }
 206
 207                 internal static bool NeedsChain (MonoTlsSettings settings)
 208                 {
 209 #if MOBILE
 210                         return false;
 211 #else
 212                         if (!is_macosx)
 213                                 return true;
 214                         if (!CertificateValidationHelper.SupportsX509Chain)
 215                                 return false;
 216                         if (settings != null)
 217                                 return !settings.SkipSystemValidators || settings.CallbackNeedsCertificateChain;
 218                         else
 219                                 return true;
 220 #endif
 221                 }
 222
 223 #if !MOBILE
 224                 static int GetStatusFromChain (X509Chain chain)
 225                 {
 226                         long result = 0;
 227                         foreach (var status in chain.ChainStatus) {
 228                                 X509ChainStatusFlags flags = status.Status;
 229                                 if (flags == X509ChainStatusFlags.NoError)
 230                                         continue;
 231
 232                                 // CERT_E_EXPIRED
 233                                 if ((flags & X509ChainStatusFlags.NotTimeValid) != 0)
 234                                         result = 0x800B0101;
 235                                 // CERT_E_VALIDITYPERIODNESTING
 236                                 else if ((flags & X509ChainStatusFlags.NotTimeNested) != 0)
 237                                         result = 0x800B0102;
 238                                 // CERT_E_REVOKED
 239                                 else if ((flags & X509ChainStatusFlags.Revoked) != 0)
 240                                         result = 0x800B010C;
 241                                 // TRUST_E_CERT_SIGNATURE
 242                                 else if ((flags & X509ChainStatusFlags.NotSignatureValid) != 0)
 243                                         result = 0x80096004;
 244                                 // CERT_E_WRONG_USAGE
 245                                 else if ((flags & X509ChainStatusFlags.NotValidForUsage) != 0)
 246                                         result = 0x800B0110;
 247                                 // CERT_E_UNTRUSTEDROOT
 248                                 else if ((flags & X509ChainStatusFlags.UntrustedRoot) != 0)
 249                                         result = 0x800B0109;
 250                                 // CRYPT_E_NO_REVOCATION_CHECK
 251                                 else if ((flags & X509ChainStatusFlags.RevocationStatusUnknown) != 0)
 252                                         result = 0x80092012;
 253                                 // CERT_E_CHAINING
 254                                 else if ((flags & X509ChainStatusFlags.Cyclic) != 0)
 255                                         result = 0x800B010A;
 256                                 // TRUST_E_FAIL - generic
 257                                 else if ((flags & X509ChainStatusFlags.InvalidExtension) != 0)
 258                                         result = 0x800B010B;
 259                                 // CERT_E_UNTRUSTEDROOT
 260                                 else if ((flags & X509ChainStatusFlags.InvalidPolicyConstraints) != 0)
 261                                         result = 0x800B010D;
 262                                 // TRUST_E_BASIC_CONSTRAINTS
 263                                 else if ((flags & X509ChainStatusFlags.InvalidBasicConstraints) != 0)
 264                                         result = 0x80096019;
 265                                 // CERT_E_INVALID_NAME
 266                                 else if ((flags & X509ChainStatusFlags.InvalidNameConstraints) != 0)
 267                                         result = 0x800B0114;
 268                                 // CERT_E_INVALID_NAME
 269                                 else if ((flags & X509ChainStatusFlags.HasNotSupportedNameConstraint) != 0)
 270                                         result = 0x800B0114;
 271                                 // CERT_E_INVALID_NAME
 272                                 else if ((flags & X509ChainStatusFlags.HasNotDefinedNameConstraint) != 0)
 273                                         result = 0x800B0114;
 274                                 // CERT_E_INVALID_NAME
 275                                 else if ((flags & X509ChainStatusFlags.HasNotPermittedNameConstraint) != 0)
 276                                         result = 0x800B0114;
 277                                 // CERT_E_INVALID_NAME
 278                                 else if ((flags & X509ChainStatusFlags.HasExcludedNameConstraint) != 0)
 279                                         result = 0x800B0114;
 280                                 // CERT_E_CHAINING
 281                                 else if ((flags & X509ChainStatusFlags.PartialChain) != 0)
 282                                         result = 0x800B010A;
 283                                 // CERT_E_EXPIRED
 284                                 else if ((flags & X509ChainStatusFlags.CtlNotTimeValid) != 0)
 285                                         result = 0x800B0101;
 286                                 // TRUST_E_CERT_SIGNATURE
 287                                 else if ((flags & X509ChainStatusFlags.CtlNotSignatureValid) != 0)
 288                                         result = 0x80096004;
 289                                 // CERT_E_WRONG_USAGE
 290                                 else if ((flags & X509ChainStatusFlags.CtlNotValidForUsage) != 0)
 291                                         result = 0x800B0110;
 292                                 // CRYPT_E_NO_REVOCATION_CHECK
 293                                 else if ((flags & X509ChainStatusFlags.OfflineRevocation) != 0)
 294                                         result = 0x80092012;
 295                                 // CERT_E_ISSUERCHAINING
 296                                 else if ((flags & X509ChainStatusFlags.NoIssuanceChainPolicy) != 0)
 297                                         result = 0x800B0107;
 298                                 else
 299                                         result = 0x800B010B; // TRUST_E_FAIL - generic
 300
 301                                 break; // Exit the loop on the first error
 302                         }
 303                         return (int)result;
 304                 }
 305
 306                 static SslPolicyErrors GetErrorsFromChain (X509Chain chain)
 307                 {
 308                         SslPolicyErrors errors = SslPolicyErrors.None;
 309                         foreach (var status in chain.ChainStatus) {
 310                                 if (status.Status == X509ChainStatusFlags.NoError)
 311                                         continue;
 312                                 errors |= SslPolicyErrors.RemoteCertificateChainErrors;
 313                                 break;
 314                         }
 315                         return errors;
 316                 }
 317 #endif
 318
 319 #if !MONOTOUCH
 320                 static X509KeyUsageFlags s_flags = X509KeyUsageFlags.DigitalSignature |
 321                         X509KeyUsageFlags.KeyAgreement |
 322                         X509KeyUsageFlags.KeyEncipherment;
 323                 // Adapted to System 2.0+ from TlsServerCertificate.cs
 324                 //------------------------------
 325                 // Note: this method only works for RSA certificates
 326                 // DH certificates requires some changes - does anyone use one ?
 327                 static bool CheckCertificateUsage (X509Certificate2 cert)
 328                 {
 329                         try {
 330                                 // certificate extensions are required for this
 331                                 // we "must" accept older certificates without proofs
 332                                 if (cert.Version < 3)
 333                                         return true;
 334
 335                                 X509KeyUsageExtension kux = (cert.Extensions ["2.5.29.15"] as X509KeyUsageExtension);
 336                                 X509EnhancedKeyUsageExtension eku = (cert.Extensions ["2.5.29.37"] as X509EnhancedKeyUsageExtension);
 337                                 if (kux != null && eku != null) {
 338                                         // RFC3280 states that when both KeyUsageExtension and
 339                                         // ExtendedKeyUsageExtension are present then BOTH should
 340                                         // be valid
 341                                         if ((kux.KeyUsages & s_flags) == 0)
 342                                                 return false;
 343                                         return eku.EnhancedKeyUsages ["1.3.6.1.5.5.7.3.1"] != null ||
 344                                                 eku.EnhancedKeyUsages ["2.16.840.1.113730.4.1"] != null;
 345                                 } else if (kux != null) {
 346                                         return ((kux.KeyUsages & s_flags) != 0);
 347                                 } else if (eku != null) {
 348                                         // Server Authentication (1.3.6.1.5.5.7.3.1) or
 349                                         // Netscape Server Gated Crypto (2.16.840.1.113730.4)
 350                                         return eku.EnhancedKeyUsages ["1.3.6.1.5.5.7.3.1"] != null ||
 351                                                 eku.EnhancedKeyUsages ["2.16.840.1.113730.4.1"] != null;
 352                                 }
 353
 354                                 // last chance - try with older (deprecated) Netscape extensions
 355                                 X509Extension ext = cert.Extensions ["2.16.840.1.113730.1.1"];
 356                                 if (ext != null) {
 357                                         string text = ext.NetscapeCertType (false);
 358                                         return text.IndexOf ("SSL Server Authentication", StringComparison.Ordinal) != -1;
 359                                 }
 360                                 return true;
 361                         } catch (Exception e) {
 362                                 Console.Error.WriteLine ("ERROR processing certificate: {0}", e);
 363                                 Console.Error.WriteLine ("Please, report this problem to the Mono team");
 364                                 return false;
 365                         }
 366                 }
 367
 368                 // RFC2818 - HTTP Over TLS, Section 3.1
 369                 // http://www.ietf.org/rfc/rfc2818.txt
 370                 //
 371                 // 1.   if present MUST use subjectAltName dNSName as identity
 372                 // 1.1.         if multiples entries a match of any one is acceptable
 373                 // 1.2.         wildcard * is acceptable
 374                 // 2.   URI may be an IP address -> subjectAltName.iPAddress
 375                 // 2.1.         exact match is required
 376                 // 3.   Use of the most specific Common Name (CN=) in the Subject
 377                 // 3.1          Existing practice but DEPRECATED
 378                 static bool CheckServerIdentity (X509Certificate2 cert, string targetHost)
 379                 {
 380                         try {
 381                                 var mcert = new MSX.X509Certificate (cert.RawData);
 382                                 MSX.X509Extension ext = mcert.Extensions ["2.5.29.17"];
 383                                 // 1. subjectAltName
 384                                 if (ext != null) {
 385                                         SubjectAltNameExtension subjectAltName = new SubjectAltNameExtension (ext);
 386                                         // 1.1 - multiple dNSName
 387                                         foreach (string dns in subjectAltName.DNSNames) {
 388                                                 // 1.2 TODO - wildcard support
 389                                                 if (Match (targetHost, dns))
 390                                                         return true;
 391                                         }
 392                                         // 2. ipAddress
 393                                         foreach (string ip in subjectAltName.IPAddresses) {
 394                                                 // 2.1. Exact match required
 395                                                 if (ip == targetHost)
 396                                                         return true;
 397                                         }
 398                                 }
 399                                 // 3. Common Name (CN=)
 400                                 return CheckDomainName (mcert.SubjectName, targetHost);
 401                         } catch (Exception e) {
 402                                 Console.Error.WriteLine ("ERROR processing certificate: {0}", e);
 403                                 Console.Error.WriteLine ("Please, report this problem to the Mono team");
 404                                 return false;
 405                         }
 406                 }
 407
 408                 static bool CheckDomainName (string subjectName, string targetHost)
 409                 {
 410                         string  domainName = String.Empty;
 411                         Regex search = new Regex (@"CN\s*=\s*([^,]*)");
 412                         MatchCollection elements = search.Matches (subjectName);
 413                         if (elements.Count == 1) {
 414                                 if (elements [0].Success)
 415                                         domainName = elements [0].Groups [1].Value.ToString ();
 416                         }
 417
 418                         return Match (targetHost, domainName);
 419                 }
 420
 421                 // ensure the pattern is valid wrt to RFC2595 and RFC2818
 422                 // http://www.ietf.org/rfc/rfc2595.txt
 423                 // http://www.ietf.org/rfc/rfc2818.txt
 424                 static bool Match (string hostname, string pattern)
 425                 {
 426                         // check if this is a pattern
 427                         int index = pattern.IndexOf ('*');
 428                         if (index == -1) {
 429                                 // not a pattern, do a direct case-insensitive comparison
 430                                 return (String.Compare (hostname, pattern, true, CultureInfo.InvariantCulture) == 0);
 431                         }
 432
 433                         // check pattern validity
 434                         // A "*" wildcard character MAY be used as the left-most name component in the certificate.
 435
 436                         // unless this is the last char (valid)
 437                         if (index != pattern.Length - 1) {
 438                                 // then the next char must be a dot .'.
 439                                 if (pattern [index + 1] != '.')
 440                                         return false;
 441                         }
 442
 443                         // only one (A) wildcard is supported
 444                         int i2 = pattern.IndexOf ('*', index + 1);
 445                         if (i2 != -1)
 446                                 return false;
 447
 448                         // match the end of the pattern
 449                         string end = pattern.Substring (index + 1);
 450                         int length = hostname.Length - end.Length;
 451                         // no point to check a pattern that is longer than the hostname
 452                         if (length <= 0)
 453                                 return false;
 454
 455                         if (String.Compare (hostname, length, end, 0, end.Length, true, CultureInfo.InvariantCulture) != 0)
 456                                 return false;
 457
 458                         // special case, we start with the wildcard
 459                         if (index == 0) {
 460                                 // ensure we hostname non-matched part (start) doesn't contain a dot
 461                                 int i3 = hostname.IndexOf ('.');
 462                                 return ((i3 == -1) || (i3 >= (hostname.Length - end.Length)));
 463                         }
 464
 465                         // match the start of the pattern
 466                         string start = pattern.Substring (0, index);
 467                         return (String.Compare (hostname, 0, start, 0, start.Length, true, CultureInfo.InvariantCulture) == 0);
 468                 }
 469 #endif
 470         }
 471 }
 472 #endif
 473