tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
Log | Files | Refs | README | LICENSE

RootCertificateTelemetryUtils.cpp (4846B)

      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 "RootCertificateTelemetryUtils.h"
      8 
      9 #include "PKCS11ModuleDB.h"
     10 #include "RootHashes.inc"  // Note: Generated by genRootCAHashes.js
     11 #include "ScopedNSSTypes.h"
     12 #include "mozilla/Logging.h"
     13 #include "nsINSSComponent.h"
     14 #include "nsServiceManagerUtils.h"
     15 #include "pk11pub.h"
     16 
     17 namespace mozilla {
     18 namespace psm {
     19 
     20 mozilla::LazyLogModule gPublicKeyPinningTelemetryLog(
     21    "PublicKeyPinningTelemetryService");
     22 
     23 // Used in the BinarySearch method, this does a memcmp between the pointer
     24 // provided to its construtor and whatever the binary search is looking for.
     25 //
     26 // This implementation assumes everything to be of HASH_LEN, so it should not
     27 // be used generically.
     28 class BinaryHashSearchArrayComparator {
     29 public:
     30  explicit BinaryHashSearchArrayComparator(const uint8_t* aTarget, size_t len)
     31      : mTarget(aTarget) {
     32    MOZ_ASSERT(len == HASH_LEN, "Hashes should be of the same length.");
     33  }
     34 
     35  int operator()(const CertAuthorityHash val) const {
     36    return memcmp(mTarget, val.hash, HASH_LEN);
     37  }
     38 
     39 private:
     40  const uint8_t* mTarget;
     41 };
     42 
     43 // Perform a hash of the provided cert, then search in the RootHashes.inc data
     44 // structure for a matching bin number.
     45 // If no matching root is found, this may be a CA from the softoken (cert9.db),
     46 // it may be a CA from an external PKCS#11 token, or it may be a CA from OS
     47 // storage (Enterprise Root).
     48 // See also the constants in RootCertificateTelemetryUtils.h.
     49 int32_t RootCABinNumber(Span<const uint8_t> cert) {
     50  nsTArray<uint8_t> digestArray;
     51 
     52  // Compute SHA256 hash of the certificate
     53  nsresult rv = Digest::DigestBuf(SEC_OID_SHA256, cert, digestArray);
     54  if (NS_WARN_IF(NS_FAILED(rv))) {
     55    return ROOT_CERTIFICATE_HASH_FAILURE;
     56  }
     57 
     58  // Compare against list of stored hashes
     59  size_t idx;
     60 
     61  MOZ_LOG(gPublicKeyPinningTelemetryLog, LogLevel::Debug,
     62          ("pkpinTelem: First bytes %02x %02x %02x %02x\n",
     63           digestArray.ElementAt(0), digestArray.ElementAt(1),
     64           digestArray.ElementAt(2), digestArray.ElementAt(3)));
     65 
     66  if (mozilla::BinarySearchIf(ROOT_TABLE, 0, std::size(ROOT_TABLE),
     67                              BinaryHashSearchArrayComparator(
     68                                  digestArray.Elements(), digestArray.Length()),
     69                              &idx)) {
     70    MOZ_LOG(gPublicKeyPinningTelemetryLog, LogLevel::Debug,
     71            ("pkpinTelem: Telemetry index was %zu, bin is %d\n", idx,
     72             ROOT_TABLE[idx].binNumber));
     73    return (int32_t)ROOT_TABLE[idx].binNumber;
     74  }
     75 
     76  // Didn't find this certificate in the built-in list. It may be an enterprise
     77  // root (gathered from the OS) or it may be from the softoken or an external
     78  // PKCS#11 token.
     79  nsCOMPtr<nsINSSComponent> component(do_GetService(PSM_COMPONENT_CONTRACTID));
     80  if (!component) {
     81    return ROOT_CERTIFICATE_UNKNOWN;
     82  }
     83  nsTArray<nsTArray<uint8_t>> enterpriseRoots;
     84  rv = component->GetEnterpriseRoots(enterpriseRoots);
     85  if (NS_FAILED(rv)) {
     86    return ROOT_CERTIFICATE_UNKNOWN;
     87  }
     88  for (const auto& enterpriseRoot : enterpriseRoots) {
     89    if (enterpriseRoot.Length() == cert.size() &&
     90        memcmp(enterpriseRoot.Elements(), cert.data(),
     91               enterpriseRoot.Length()) == 0) {
     92      return ROOT_CERTIFICATE_ENTERPRISE_ROOT;
     93    }
     94  }
     95 
     96  SECItem certItem = {siBuffer, const_cast<uint8_t*>(cert.data()),
     97                      static_cast<unsigned int>(cert.size())};
     98  UniquePK11SlotInfo softokenSlot(PK11_GetInternalKeySlot());
     99  if (!softokenSlot) {
    100    return ROOT_CERTIFICATE_UNKNOWN;
    101  }
    102  CK_OBJECT_HANDLE softokenCertHandle =
    103      PK11_FindEncodedCertInSlot(softokenSlot.get(), &certItem, nullptr);
    104  if (softokenCertHandle != CK_INVALID_HANDLE) {
    105    return ROOT_CERTIFICATE_SOFTOKEN;
    106  }
    107  // In theory this should never find the certificate in the root module,
    108  // because then it should have already matched our built-in list. This is
    109  // here as a backstop to catch situations where a built-in root was added but
    110  // the built-in telemetry information was not updated.
    111  UniqueSECMODModule rootsModule(SECMOD_FindModule(kRootModuleName.get()));
    112  AutoSECMODListReadLock secmodLock;
    113  if (!rootsModule || rootsModule->slotCount != 1) {
    114    return ROOT_CERTIFICATE_UNKNOWN;
    115  }
    116  CK_OBJECT_HANDLE builtinCertHandle =
    117      PK11_FindEncodedCertInSlot(rootsModule->slots[0], &certItem, nullptr);
    118  if (builtinCertHandle == CK_INVALID_HANDLE) {
    119    return ROOT_CERTIFICATE_EXTERNAL_TOKEN;
    120  }
    121 
    122  // We have no idea what this is.
    123  return ROOT_CERTIFICATE_UNKNOWN;
    124 }
    125 
    126 }  // namespace psm
    127 }  // namespace mozilla