components/packed_ct_ev_whitelist/packed_ct_ev_whitelist.cc

   1 // Copyright 2014 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 "components/packed_ct_ev_whitelist/packed_ct_ev_whitelist.h"
   6
   7 #include <string.h>
   8
   9 #include <algorithm>
  10
  11 #include "base/big_endian.h"
  12 #include "base/files/file_util.h"
  13 #include "base/lazy_instance.h"
  14 #include "base/logging.h"
  15 #include "components/packed_ct_ev_whitelist/bit_stream_reader.h"
  16 #include "content/public/browser/browser_thread.h"
  17 #include "net/ssl/ssl_config_service.h"
  18
  19 namespace {
  20 const uint8_t kCertHashLengthBits = 64;  // 8 bytes
  21 const uint8_t kCertHashLength = kCertHashLengthBits / 8;
  22 const uint64_t kGolombMParameterBits = 47;  // 2^47
  23
  24 void SetEVWhitelistInSSLConfigService(
  25     const scoped_refptr<net::ct::EVCertsWhitelist>& new_whitelist) {
  26   VLOG(1) << "Setting new EV Certs whitelist.";
  27   net::SSLConfigService::SetEVCertsWhitelist(new_whitelist);
  28 }
  29
  30 int TruncatedHashesComparator(const void* v1, const void* v2) {
  31   const uint64_t& h1(*(static_cast<const uint64_t*>(v1)));
  32   const uint64_t& h2(*(static_cast<const uint64_t*>(v2)));
  33   if (h1 < h2)
  34     return -1;
  35   else if (h1 > h2)
  36     return 1;
  37   return 0;
  38 }
  39 }  // namespace
  40
  41 namespace packed_ct_ev_whitelist {
  42
  43 void SetEVCertsWhitelist(scoped_refptr<net::ct::EVCertsWhitelist> whitelist) {
  44   if (!whitelist->IsValid()) {
  45     VLOG(1) << "EV Certs whitelist is not valid, not setting.";
  46     return;
  47   }
  48
  49   base::Closure assign_cb =
  50       base::Bind(SetEVWhitelistInSSLConfigService, whitelist);
  51   content::BrowserThread::PostTask(
  52       content::BrowserThread::IO, FROM_HERE, assign_cb);
  53 }
  54
  55 bool PackedEVCertsWhitelist::UncompressEVWhitelist(
  56     const std::string& compressed_whitelist,
  57     std::vector<uint64_t>* uncompressed_list) {
  58   internal::BitStreamReader reader(base::StringPiece(
  59       compressed_whitelist.data(), compressed_whitelist.size()));
  60   std::vector<uint64_t> result;
  61
  62   VLOG(1) << "Uncompressing EV whitelist of size "
  63           << compressed_whitelist.size();
  64   uint64_t curr_hash(0);
  65   if (!reader.ReadBits(kCertHashLengthBits, &curr_hash)) {
  66     VLOG(1) << "Failed reading first hash.";
  67     return false;
  68   }
  69   result.push_back(curr_hash);
  70   // M is the tunable parameter used by the Golomb coding.
  71   static const uint64_t kGolombParameterM = static_cast<uint64_t>(1)
  72                                             << kGolombMParameterBits;
  73
  74   while (reader.BitsLeft() > kGolombMParameterBits) {
  75     uint64_t read_prefix = 0;
  76     if (!reader.ReadUnaryEncoding(&read_prefix)) {
  77       VLOG(1) << "Failed reading unary-encoded prefix.";
  78       return false;
  79     }
  80     if (read_prefix > (UINT64_MAX / kGolombParameterM)) {
  81       VLOG(1) << "Received value that would cause overflow: " << read_prefix;
  82       return false;
  83     }
  84
  85     uint64_t r = 0;
  86     if (!reader.ReadBits(kGolombMParameterBits, &r)) {
  87       VLOG(1) << "Failed reading " << kGolombMParameterBits << " bits.";
  88       return false;
  89     }
  90     DCHECK_LT(r, kGolombParameterM);
  91
  92     uint64_t curr_diff = read_prefix * kGolombParameterM + r;
  93     curr_hash += curr_diff;
  94
  95     result.push_back(curr_hash);
  96   }
  97
  98   uncompressed_list->swap(result);
  99   return true;
 100 }
 101
 102 PackedEVCertsWhitelist::PackedEVCertsWhitelist(
 103     const std::string& compressed_whitelist,
 104     const base::Version& version)
 105     : version_(version) {
 106   if (!UncompressEVWhitelist(compressed_whitelist, &whitelist_)) {
 107     whitelist_.clear();
 108     return;
 109   }
 110 }
 111
 112 PackedEVCertsWhitelist::~PackedEVCertsWhitelist() {
 113 }
 114
 115 bool PackedEVCertsWhitelist::ContainsCertificateHash(
 116     const std::string& certificate_hash) const {
 117   DCHECK(!whitelist_.empty());
 118   uint64_t hash_to_lookup;
 119
 120   base::ReadBigEndian(certificate_hash.data(), &hash_to_lookup);
 121   return bsearch(&hash_to_lookup,
 122                  &whitelist_[0],
 123                  whitelist_.size(),
 124                  kCertHashLength,
 125                  TruncatedHashesComparator) != NULL;
 126 }
 127
 128 bool PackedEVCertsWhitelist::IsValid() const {
 129   return whitelist_.size() > 0;
 130 }
 131
 132 base::Version PackedEVCertsWhitelist::Version() const {
 133   return version_;
 134 }
 135
 136 }  // namespace packed_ct_ev_whitelist