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