net/cert/cert_verify_proc.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/cert/cert_verify_proc.h"
   6
   7 #include "base/metrics/histogram.h"
   8 #include "base/sha1.h"
   9 #include "build/build_config.h"
  10 #include "net/base/net_errors.h"
  11 #include "net/cert/cert_status_flags.h"
  12 #include "net/cert/cert_verifier.h"
  13 #include "net/cert/cert_verify_result.h"
  14 #include "net/cert/crl_set.h"
  15 #include "net/cert/x509_certificate.h"
  16
  17 #if defined(USE_NSS) || defined(OS_IOS)
  18 #include "net/cert/cert_verify_proc_nss.h"
  19 #elif defined(USE_OPENSSL) && !defined(OS_ANDROID)
  20 #include "net/cert/cert_verify_proc_openssl.h"
  21 #elif defined(OS_ANDROID)
  22 #include "net/cert/cert_verify_proc_android.h"
  23 #elif defined(OS_MACOSX)
  24 #include "net/cert/cert_verify_proc_mac.h"
  25 #elif defined(OS_WIN)
  26 #include "net/cert/cert_verify_proc_win.h"
  27 #else
  28 #error Implement certificate verification.
  29 #endif
  30
  31
  32 namespace net {
  33
  34 namespace {
  35
  36 // Returns true if |type| is |kPublicKeyTypeRSA| or |kPublicKeyTypeDSA|, and
  37 // if |size_bits| is < 1024. Note that this means there may be false
  38 // negatives: keys for other algorithms and which are weak will pass this
  39 // test.
  40 bool IsWeakKey(X509Certificate::PublicKeyType type, size_t size_bits) {
  41   switch (type) {
  42     case X509Certificate::kPublicKeyTypeRSA:
  43     case X509Certificate::kPublicKeyTypeDSA:
  44       return size_bits < 1024;
  45     default:
  46       return false;
  47   }
  48 }
  49
  50 }  // namespace
  51
  52 // static
  53 CertVerifyProc* CertVerifyProc::CreateDefault() {
  54 #if defined(USE_NSS) || defined(OS_IOS)
  55   return new CertVerifyProcNSS();
  56 #elif defined(USE_OPENSSL) && !defined(OS_ANDROID)
  57   return new CertVerifyProcOpenSSL();
  58 #elif defined(OS_ANDROID)
  59   return new CertVerifyProcAndroid();
  60 #elif defined(OS_MACOSX)
  61   return new CertVerifyProcMac();
  62 #elif defined(OS_WIN)
  63   return new CertVerifyProcWin();
  64 #else
  65   return NULL;
  66 #endif
  67 }
  68
  69 CertVerifyProc::CertVerifyProc() {}
  70
  71 CertVerifyProc::~CertVerifyProc() {}
  72
  73 int CertVerifyProc::Verify(X509Certificate* cert,
  74                            const std::string& hostname,
  75                            int flags,
  76                            CRLSet* crl_set,
  77                            const CertificateList& additional_trust_anchors,
  78                            CertVerifyResult* verify_result) {
  79   verify_result->Reset();
  80   verify_result->verified_cert = cert;
  81
  82   if (IsBlacklisted(cert)) {
  83     verify_result->cert_status |= CERT_STATUS_REVOKED;
  84     return ERR_CERT_REVOKED;
  85   }
  86
  87   // If EV verification was requested and no CRLSet is present, or if the
  88   // CRLSet has expired, then enable online revocation checks. If the online
  89   // check fails, EV status won't be shown.
  90   //
  91   // TODO(rsleevi): http://crbug.com/142974 - Allow preferences to fully
  92   // disable revocation checking.
  93   if ((flags & CertVerifier::VERIFY_EV_CERT) &&
  94       (!crl_set || crl_set->IsExpired())) {
  95     flags |= CertVerifier::VERIFY_REV_CHECKING_ENABLED_EV_ONLY;
  96   }
  97
  98   int rv = VerifyInternal(cert, hostname, flags, crl_set,
  99                           additional_trust_anchors, verify_result);
 100
 101   // This check is done after VerifyInternal so that VerifyInternal can fill
 102   // in the list of public key hashes.
 103   if (IsPublicKeyBlacklisted(verify_result->public_key_hashes)) {
 104     verify_result->cert_status |= CERT_STATUS_REVOKED;
 105     rv = MapCertStatusToNetError(verify_result->cert_status);
 106   }
 107
 108   // Check for weak keys in the entire verified chain.
 109   size_t size_bits = 0;
 110   X509Certificate::PublicKeyType type =
 111       X509Certificate::kPublicKeyTypeUnknown;
 112   bool weak_key = false;
 113
 114   X509Certificate::GetPublicKeyInfo(
 115       verify_result->verified_cert->os_cert_handle(), &size_bits, &type);
 116   if (IsWeakKey(type, size_bits)) {
 117     weak_key = true;
 118   } else {
 119     const X509Certificate::OSCertHandles& intermediates =
 120         verify_result->verified_cert->GetIntermediateCertificates();
 121     for (size_t i = 0; i < intermediates.size(); ++i) {
 122       X509Certificate::GetPublicKeyInfo(intermediates[i], &size_bits, &type);
 123       if (IsWeakKey(type, size_bits))
 124         weak_key = true;
 125     }
 126   }
 127
 128   if (weak_key) {
 129     verify_result->cert_status |= CERT_STATUS_WEAK_KEY;
 130     // Avoid replacing a more serious error, such as an OS/library failure,
 131     // by ensuring that if verification failed, it failed with a certificate
 132     // error.
 133     if (rv == OK || IsCertificateError(rv))
 134       rv = MapCertStatusToNetError(verify_result->cert_status);
 135   }
 136
 137   // Treat certificates signed using broken signature algorithms as invalid.
 138   if (verify_result->has_md2 || verify_result->has_md4) {
 139     verify_result->cert_status |= CERT_STATUS_INVALID;
 140     rv = MapCertStatusToNetError(verify_result->cert_status);
 141   }
 142
 143   // Flag certificates using weak signature algorithms.
 144   if (verify_result->has_md5) {
 145     verify_result->cert_status |= CERT_STATUS_WEAK_SIGNATURE_ALGORITHM;
 146     // Avoid replacing a more serious error, such as an OS/library failure,
 147     // by ensuring that if verification failed, it failed with a certificate
 148     // error.
 149     if (rv == OK || IsCertificateError(rv))
 150       rv = MapCertStatusToNetError(verify_result->cert_status);
 151   }
 152
 153   return rv;
 154 }
 155
 156 // static
 157 bool CertVerifyProc::IsBlacklisted(X509Certificate* cert) {
 158   static const unsigned kComodoSerialBytes = 16;
 159   static const uint8 kComodoSerials[][kComodoSerialBytes] = {
 160     // Not a real certificate. For testing only.
 161     {0x07,0x7a,0x59,0xbc,0xd5,0x34,0x59,0x60,0x1c,0xa6,0x90,0x72,0x67,0xa6,0xdd,0x1c},
 162
 163     // The next nine certificates all expire on Fri Mar 14 23:59:59 2014.
 164     // Some serial numbers actually have a leading 0x00 byte required to
 165     // encode a positive integer in DER if the most significant bit is 0.
 166     // We omit the leading 0x00 bytes to make all serial numbers 16 bytes.
 167
 168     // Subject: CN=mail.google.com
 169     // subjectAltName dNSName: mail.google.com, www.mail.google.com
 170     {0x04,0x7e,0xcb,0xe9,0xfc,0xa5,0x5f,0x7b,0xd0,0x9e,0xae,0x36,0xe1,0x0c,0xae,0x1e},
 171     // Subject: CN=global trustee
 172     // subjectAltName dNSName: global trustee
 173     // Note: not a CA certificate.
 174     {0xd8,0xf3,0x5f,0x4e,0xb7,0x87,0x2b,0x2d,0xab,0x06,0x92,0xe3,0x15,0x38,0x2f,0xb0},
 175     // Subject: CN=login.live.com
 176     // subjectAltName dNSName: login.live.com, www.login.live.com
 177     {0xb0,0xb7,0x13,0x3e,0xd0,0x96,0xf9,0xb5,0x6f,0xae,0x91,0xc8,0x74,0xbd,0x3a,0xc0},
 178     // Subject: CN=addons.mozilla.org
 179     // subjectAltName dNSName: addons.mozilla.org, www.addons.mozilla.org
 180     {0x92,0x39,0xd5,0x34,0x8f,0x40,0xd1,0x69,0x5a,0x74,0x54,0x70,0xe1,0xf2,0x3f,0x43},
 181     // Subject: CN=login.skype.com
 182     // subjectAltName dNSName: login.skype.com, www.login.skype.com
 183     {0xe9,0x02,0x8b,0x95,0x78,0xe4,0x15,0xdc,0x1a,0x71,0x0a,0x2b,0x88,0x15,0x44,0x47},
 184     // Subject: CN=login.yahoo.com
 185     // subjectAltName dNSName: login.yahoo.com, www.login.yahoo.com
 186     {0xd7,0x55,0x8f,0xda,0xf5,0xf1,0x10,0x5b,0xb2,0x13,0x28,0x2b,0x70,0x77,0x29,0xa3},
 187     // Subject: CN=www.google.com
 188     // subjectAltName dNSName: www.google.com, google.com
 189     {0xf5,0xc8,0x6a,0xf3,0x61,0x62,0xf1,0x3a,0x64,0xf5,0x4f,0x6d,0xc9,0x58,0x7c,0x06},
 190     // Subject: CN=login.yahoo.com
 191     // subjectAltName dNSName: login.yahoo.com
 192     {0x39,0x2a,0x43,0x4f,0x0e,0x07,0xdf,0x1f,0x8a,0xa3,0x05,0xde,0x34,0xe0,0xc2,0x29},
 193     // Subject: CN=login.yahoo.com
 194     // subjectAltName dNSName: login.yahoo.com
 195     {0x3e,0x75,0xce,0xd4,0x6b,0x69,0x30,0x21,0x21,0x88,0x30,0xae,0x86,0xa8,0x2a,0x71},
 196   };
 197
 198   const std::string& serial_number = cert->serial_number();
 199   if (!serial_number.empty() && (serial_number[0] & 0x80) != 0) {
 200     // This is a negative serial number, which isn't technically allowed but
 201     // which probably happens. In order to avoid confusing a negative serial
 202     // number with a positive one once the leading zeros have been removed, we
 203     // disregard it.
 204     return false;
 205   }
 206
 207   base::StringPiece serial(serial_number);
 208   // Remove leading zeros.
 209   while (serial.size() > 1 && serial[0] == 0)
 210     serial.remove_prefix(1);
 211
 212   if (serial.size() == kComodoSerialBytes) {
 213     for (unsigned i = 0; i < arraysize(kComodoSerials); i++) {
 214       if (memcmp(kComodoSerials[i], serial.data(), kComodoSerialBytes) == 0) {
 215         UMA_HISTOGRAM_ENUMERATION("Net.SSLCertBlacklisted", i,
 216                                   arraysize(kComodoSerials) + 1);
 217         return true;
 218       }
 219     }
 220   }
 221
 222   return false;
 223 }
 224
 225 // static
 226 // NOTE: This implementation assumes and enforces that the hashes are SHA1.
 227 bool CertVerifyProc::IsPublicKeyBlacklisted(
 228     const HashValueVector& public_key_hashes) {
 229   static const unsigned kNumHashes = 10;
 230   static const uint8 kHashes[kNumHashes][base::kSHA1Length] = {
 231     // Subject: CN=DigiNotar Root CA
 232     // Issuer: CN=Entrust.net x2 and self-signed
 233     {0x41, 0x0f, 0x36, 0x36, 0x32, 0x58, 0xf3, 0x0b, 0x34, 0x7d,
 234      0x12, 0xce, 0x48, 0x63, 0xe4, 0x33, 0x43, 0x78, 0x06, 0xa8},
 235     // Subject: CN=DigiNotar Cyber CA
 236     // Issuer: CN=GTE CyberTrust Global Root
 237     {0xc4, 0xf9, 0x66, 0x37, 0x16, 0xcd, 0x5e, 0x71, 0xd6, 0x95,
 238      0x0b, 0x5f, 0x33, 0xce, 0x04, 0x1c, 0x95, 0xb4, 0x35, 0xd1},
 239     // Subject: CN=DigiNotar Services 1024 CA
 240     // Issuer: CN=Entrust.net
 241     {0xe2, 0x3b, 0x8d, 0x10, 0x5f, 0x87, 0x71, 0x0a, 0x68, 0xd9,
 242      0x24, 0x80, 0x50, 0xeb, 0xef, 0xc6, 0x27, 0xbe, 0x4c, 0xa6},
 243     // Subject: CN=DigiNotar PKIoverheid CA Organisatie - G2
 244     // Issuer: CN=Staat der Nederlanden Organisatie CA - G2
 245     {0x7b, 0x2e, 0x16, 0xbc, 0x39, 0xbc, 0xd7, 0x2b, 0x45, 0x6e,
 246      0x9f, 0x05, 0x5d, 0x1d, 0xe6, 0x15, 0xb7, 0x49, 0x45, 0xdb},
 247     // Subject: CN=DigiNotar PKIoverheid CA Overheid en Bedrijven
 248     // Issuer: CN=Staat der Nederlanden Overheid CA
 249     {0xe8, 0xf9, 0x12, 0x00, 0xc6, 0x5c, 0xee, 0x16, 0xe0, 0x39,
 250      0xb9, 0xf8, 0x83, 0x84, 0x16, 0x61, 0x63, 0x5f, 0x81, 0xc5},
 251     // Subject: O=Digicert Sdn. Bhd.
 252     // Issuer: CN=GTE CyberTrust Global Root
 253     // Expires: Jul 17 15:16:54 2012 GMT
 254     {0x01, 0x29, 0xbc, 0xd5, 0xb4, 0x48, 0xae, 0x8d, 0x24, 0x96,
 255      0xd1, 0xc3, 0xe1, 0x97, 0x23, 0x91, 0x90, 0x88, 0xe1, 0x52},
 256     // Subject: O=Digicert Sdn. Bhd.
 257     // Issuer: CN=Entrust.net Certification Authority (2048)
 258     // Expires: Jul 16 17:53:37 2015 GMT
 259     {0xd3, 0x3c, 0x5b, 0x41, 0xe4, 0x5c, 0xc4, 0xb3, 0xbe, 0x9a,
 260      0xd6, 0x95, 0x2c, 0x4e, 0xcc, 0x25, 0x28, 0x03, 0x29, 0x81},
 261     // Issuer: CN=Trustwave Organization Issuing CA, Level 2
 262     // Covers two certificates, the latter of which expires Apr 15 21:09:30
 263     // 2021 GMT.
 264     {0xe1, 0x2d, 0x89, 0xf5, 0x6d, 0x22, 0x76, 0xf8, 0x30, 0xe6,
 265      0xce, 0xaf, 0xa6, 0x6c, 0x72, 0x5c, 0x0b, 0x41, 0xa9, 0x32},
 266     // Cyberoam CA certificate. Private key leaked, but this certificate would
 267     // only have been installed by Cyberoam customers. The certificate expires
 268     // in 2036, but we can probably remove in a couple of years (2014).
 269     {0xd9, 0xf5, 0xc6, 0xce, 0x57, 0xff, 0xaa, 0x39, 0xcc, 0x7e,
 270      0xd1, 0x72, 0xbd, 0x53, 0xe0, 0xd3, 0x07, 0x83, 0x4b, 0xd1},
 271     // Win32/Sirefef.gen!C generates fake certifciates with this public key.
 272     {0xa4, 0xf5, 0x6e, 0x9e, 0x1d, 0x9a, 0x3b, 0x7b, 0x1a, 0xc3,
 273      0x31, 0xcf, 0x64, 0xfc, 0x76, 0x2c, 0xd0, 0x51, 0xfb, 0xa4},
 274   };
 275
 276   for (unsigned i = 0; i < kNumHashes; i++) {
 277     for (HashValueVector::const_iterator j = public_key_hashes.begin();
 278          j != public_key_hashes.end(); ++j) {
 279       if (j->tag == HASH_VALUE_SHA1 &&
 280           memcmp(j->data(), kHashes[i], base::kSHA1Length) == 0) {
 281         return true;
 282       }
 283     }
 284   }
 285
 286   return false;
 287 }
 288
 289 }  // namespace net