security/ct/MultiLogCTVerifier.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "MultiLogCTVerifier.h"
   8
   9 #include "CTObjectsExtractor.h"
  10 #include "CTSerialization.h"
  11 #include "mozilla/StaticPrefs_security.h"
  12
  13 namespace mozilla {
  14 namespace ct {
  15
  16 using namespace mozilla::pkix;
  17
  18 MultiLogCTVerifier::MultiLogCTVerifier()
  19     : mSignatureCache(signature_cache_new(
  20                           StaticPrefs::security_pki_sct_signature_cache_size()),
  21                       signature_cache_free) {}
  22
  23 void MultiLogCTVerifier::AddLog(CTLogVerifier&& log) {
  24   mLogs.push_back(std::move(log));
  25 }
  26
  27 pkix::Result MultiLogCTVerifier::Verify(Input cert,
  28                                         Input issuerSubjectPublicKeyInfo,
  29                                         Input sctListFromCert,
  30                                         Input sctListFromOCSPResponse,
  31                                         Input sctListFromTLSExtension,
  32                                         Time time, CTVerifyResult& result) {
  33   assert(cert.GetLength() > 0);
  34   result.Reset();
  35
  36   pkix::Result rv;
  37
  38   // Verify embedded SCTs
  39   if (issuerSubjectPublicKeyInfo.GetLength() > 0 &&
  40       sctListFromCert.GetLength() > 0) {
  41     LogEntry precertEntry;
  42     rv = GetPrecertLogEntry(cert, issuerSubjectPublicKeyInfo, precertEntry);
  43     if (rv != Success) {
  44       return rv;
  45     }
  46     rv = VerifySCTs(sctListFromCert, precertEntry, SCTOrigin::Embedded, time,
  47                     result);
  48     if (rv != Success) {
  49       return rv;
  50     }
  51   }
  52
  53   LogEntry x509Entry;
  54   GetX509LogEntry(cert, x509Entry);
  55
  56   // Verify SCTs from a stapled OCSP response
  57   if (sctListFromOCSPResponse.GetLength() > 0) {
  58     rv = VerifySCTs(sctListFromOCSPResponse, x509Entry, SCTOrigin::OCSPResponse,
  59                     time, result);
  60     if (rv != Success) {
  61       return rv;
  62     }
  63   }
  64
  65   // Verify SCTs from a TLS extension
  66   if (sctListFromTLSExtension.GetLength() > 0) {
  67     rv = VerifySCTs(sctListFromTLSExtension, x509Entry, SCTOrigin::TLSExtension,
  68                     time, result);
  69     if (rv != Success) {
  70       return rv;
  71     }
  72   }
  73   return Success;
  74 }
  75
  76 void DecodeSCTs(Input encodedSctList,
  77                 std::vector<SignedCertificateTimestamp>& decodedSCTs,
  78                 size_t& decodingErrors) {
  79   decodedSCTs.clear();
  80
  81   Reader listReader;
  82   pkix::Result rv = DecodeSCTList(encodedSctList, listReader);
  83   if (rv != Success) {
  84     decodingErrors++;
  85     return;
  86   }
  87
  88   while (!listReader.AtEnd()) {
  89     Input encodedSct;
  90     rv = ReadSCTListItem(listReader, encodedSct);
  91     if (rv != Success) {
  92       decodingErrors++;
  93       return;
  94     }
  95
  96     Reader encodedSctReader(encodedSct);
  97     SignedCertificateTimestamp sct;
  98     rv = DecodeSignedCertificateTimestamp(encodedSctReader, sct);
  99     if (rv != Success) {
 100       decodingErrors++;
 101       continue;
 102     }
 103     decodedSCTs.push_back(std::move(sct));
 104   }
 105 }
 106
 107 pkix::Result MultiLogCTVerifier::VerifySCTs(Input encodedSctList,
 108                                             const LogEntry& expectedEntry,
 109                                             SCTOrigin origin, Time time,
 110                                             CTVerifyResult& result) {
 111   std::vector<SignedCertificateTimestamp> decodedSCTs;
 112   DecodeSCTs(encodedSctList, decodedSCTs, result.decodingErrors);
 113   for (auto sct : decodedSCTs) {
 114     pkix::Result rv =
 115         VerifySingleSCT(std::move(sct), expectedEntry, origin, time, result);
 116     if (rv != Success) {
 117       return rv;
 118     }
 119   }
 120   return Success;
 121 }
 122
 123 pkix::Result MultiLogCTVerifier::VerifySingleSCT(
 124     SignedCertificateTimestamp&& sct, const LogEntry& expectedEntry,
 125     SCTOrigin origin, Time time, CTVerifyResult& result) {
 126   switch (origin) {
 127     case SCTOrigin::Embedded:
 128       result.embeddedSCTs++;
 129       break;
 130     case SCTOrigin::TLSExtension:
 131       result.sctsFromTLSHandshake++;
 132       break;
 133     case SCTOrigin::OCSPResponse:
 134       result.sctsFromOCSP++;
 135       break;
 136   }
 137
 138   CTLogVerifier* matchingLog = nullptr;
 139   for (auto& log : mLogs) {
 140     if (log.keyId() == sct.logId) {
 141       matchingLog = &log;
 142       break;
 143     }
 144   }
 145
 146   if (!matchingLog) {
 147     // SCT does not match any known log.
 148     result.sctsFromUnknownLogs++;
 149     return Success;
 150   }
 151
 152   if (!matchingLog->SignatureParametersMatch(sct.signature)) {
 153     // SCT signature parameters do not match the log's.
 154     result.sctsWithInvalidSignatures++;
 155     return Success;
 156   }
 157
 158   pkix::Result rv =
 159       matchingLog->Verify(expectedEntry, sct, mSignatureCache.get());
 160   if (rv != Success) {
 161     if (rv == pkix::Result::ERROR_BAD_SIGNATURE) {
 162       result.sctsWithInvalidSignatures++;
 163       return Success;
 164     }
 165     return rv;
 166   }
 167
 168   // Make sure the timestamp is legitimate (not in the future).
 169   // SCT's |timestamp| is measured in milliseconds since the epoch,
 170   // ignoring leap seconds. When converting it to a second-level precision
 171   // pkix::Time, we need to round it either up or down. In our case, rounding up
 172   // (towards the future) is more "secure", although practically
 173   // it does not matter.
 174   Time sctTime = TimeFromEpochInSeconds((sct.timestamp + 999u) / 1000u);
 175   if (sctTime > time) {
 176     result.sctsWithInvalidTimestamps++;
 177     return Success;
 178   }
 179
 180   VerifiedSCT verifiedSct(std::move(sct), origin, matchingLog->operatorId(),
 181                           matchingLog->state(), matchingLog->timestamp());
 182   result.verifiedScts.push_back(std::move(verifiedSct));
 183   return Success;
 184 }
 185
 186 }  // namespace ct
 187 }  // namespace mozilla