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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "RootCertificateTelemetryUtils.h"
#include "RootHashes.inc" // Note: Generated by genRootCAHashes.js
#include "ScopedNSSTypes.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/Logging.h"
#include "nsINSSComponent.h"
#include "nsNSSCertHelper.h"
#include "nsServiceManagerUtils.h"
#include "pk11pub.h"
namespace mozilla {
namespace psm {
mozilla::LazyLogModule gPublicKeyPinningTelemetryLog(
"PublicKeyPinningTelemetryService");
// Used in the BinarySearch method, this does a memcmp between the pointer
// provided to its construtor and whatever the binary search is looking for.
//
// This implementation assumes everything to be of HASH_LEN, so it should not
// be used generically.
class BinaryHashSearchArrayComparator {
public:
explicit BinaryHashSearchArrayComparator(const uint8_t* aTarget, size_t len)
: mTarget(aTarget) {
MOZ_ASSERT(len == HASH_LEN, "Hashes should be of the same length.");
}
int operator()(const CertAuthorityHash val) const {
return memcmp(mTarget, val.hash, HASH_LEN);
}
private:
const uint8_t* mTarget;
};
// Perform a hash of the provided cert, then search in the RootHashes.inc data
// structure for a matching bin number.
// If no matching root is found, this may be a CA from the softoken (cert9.db),
// it may be a CA from an external PKCS#11 token, or it may be a CA from OS
// storage (Enterprise Root).
// See also the constants in RootCertificateTelemetryUtils.h.
int32_t RootCABinNumber(Span<const uint8_t> cert) {
nsTArray<uint8_t> digestArray;
// Compute SHA256 hash of the certificate
nsresult rv = Digest::DigestBuf(SEC_OID_SHA256, cert, digestArray);
if (NS_WARN_IF(NS_FAILED(rv))) {
return ROOT_CERTIFICATE_HASH_FAILURE;
}
// Compare against list of stored hashes
size_t idx;
MOZ_LOG(gPublicKeyPinningTelemetryLog, LogLevel::Debug,
("pkpinTelem: First bytes %02x %02x %02x %02x\n",
digestArray.ElementAt(0), digestArray.ElementAt(1),
digestArray.ElementAt(2), digestArray.ElementAt(3)));
if (mozilla::BinarySearchIf(ROOT_TABLE, 0, ArrayLength(ROOT_TABLE),
BinaryHashSearchArrayComparator(
digestArray.Elements(), digestArray.Length()),
&idx)) {
MOZ_LOG(gPublicKeyPinningTelemetryLog, LogLevel::Debug,
("pkpinTelem: Telemetry index was %zu, bin is %d\n", idx,
ROOT_TABLE[idx].binNumber));
return (int32_t)ROOT_TABLE[idx].binNumber;
}
// Didn't find this certificate in the built-in list. It may be an enterprise
// root (gathered from the OS) or it may be from the softoken or an external
// PKCS#11 token.
nsCOMPtr<nsINSSComponent> component(do_GetService(PSM_COMPONENT_CONTRACTID));
if (!component) {
return ROOT_CERTIFICATE_UNKNOWN;
}
nsTArray<nsTArray<uint8_t>> enterpriseRoots;
rv = component->GetEnterpriseRoots(enterpriseRoots);
if (NS_FAILED(rv)) {
return ROOT_CERTIFICATE_UNKNOWN;
}
for (const auto& enterpriseRoot : enterpriseRoots) {
if (enterpriseRoot.Length() == cert.size() &&
memcmp(enterpriseRoot.Elements(), cert.data(),
enterpriseRoot.Length()) == 0) {
return ROOT_CERTIFICATE_ENTERPRISE_ROOT;
}
}
SECItem certItem = {siBuffer, const_cast<uint8_t*>(cert.data()),
static_cast<unsigned int>(cert.size())};
UniquePK11SlotInfo softokenSlot(PK11_GetInternalKeySlot());
if (!softokenSlot) {
return ROOT_CERTIFICATE_UNKNOWN;
}
CK_OBJECT_HANDLE softokenCertHandle =
PK11_FindEncodedCertInSlot(softokenSlot.get(), &certItem, nullptr);
if (softokenCertHandle != CK_INVALID_HANDLE) {
return ROOT_CERTIFICATE_SOFTOKEN;
}
// In theory this should never find the certificate in the root module,
// because then it should have already matched our built-in list. This is
// here as a backstop to catch situations where a built-in root was added but
// the built-in telemetry information was not updated.
UniqueSECMODModule rootsModule(SECMOD_FindModule(kRootModuleName));
AutoSECMODListReadLock secmodLock;
if (!rootsModule || rootsModule->slotCount != 1) {
return ROOT_CERTIFICATE_UNKNOWN;
}
CK_OBJECT_HANDLE builtinCertHandle =
PK11_FindEncodedCertInSlot(rootsModule->slots[0], &certItem, nullptr);
if (builtinCertHandle == CK_INVALID_HANDLE) {
return ROOT_CERTIFICATE_EXTERNAL_TOKEN;
}
// We have no idea what this is.
return ROOT_CERTIFICATE_UNKNOWN;
}
// Attempt to increment the appropriate bin in the provided Telemetry probe ID.
// If there was a hash failure, we do nothing.
void AccumulateTelemetryForRootCA(mozilla::Telemetry::HistogramID probe,
const Span<const uint8_t> cert) {
int32_t binId = RootCABinNumber(cert);
if (binId != ROOT_CERTIFICATE_HASH_FAILURE) {
Accumulate(probe, binId);
}
}
} // namespace psm
} // namespace mozilla
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