gecko-dev/security/apps/AppTrustDomain.cpp

/* -*- 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 "AppTrustDomain.h"

#include "MainThreadUtils.h"
#include "certdb.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/Casting.h"
#include "mozilla/Preferences.h"
#include "nsComponentManagerUtils.h"
#include "nsIFile.h"
#include "nsIFileStreams.h"
#include "nsIX509CertDB.h"
#include "nsNSSCertificate.h"
#include "nsNetUtil.h"
#include "mozpkix/pkixnss.h"
#include "prerror.h"

// Generated by gen_cert_header.py, which gets called by the build system.
#include "xpcshell.inc"
// Add-on signing Certificates
#include "addons-public.inc"
#include "addons-public-intermediate.inc"
#include "addons-stage.inc"
// Privileged Package Certificates
#include "privileged-package-root.inc"

using namespace mozilla::pkix;

extern mozilla::LazyLogModule gPIPNSSLog;

static char kDevImportedDER[] = "network.http.signed-packages.developer-root";

namespace mozilla {
namespace psm {

StaticMutex AppTrustDomain::sMutex;
UniquePtr<unsigned char[]> AppTrustDomain::sDevImportedDERData;
unsigned int AppTrustDomain::sDevImportedDERLen = 0;

AppTrustDomain::AppTrustDomain(UniqueCERTCertList& certChain, void* pinArg)
    : mCertChain(certChain), mPinArg(pinArg) {}

nsresult AppTrustDomain::SetTrustedRoot(AppTrustedRoot trustedRoot) {
  SECItem trustedDER;

  // Load the trusted certificate into the in-memory NSS database so that
  // CERT_CreateSubjectCertList can find it.

  switch (trustedRoot) {
    case nsIX509CertDB::AppXPCShellRoot:
      trustedDER.data = const_cast<uint8_t*>(xpcshellRoot);
      trustedDER.len = mozilla::ArrayLength(xpcshellRoot);
      break;

    case nsIX509CertDB::AddonsPublicRoot:
      trustedDER.data = const_cast<uint8_t*>(addonsPublicRoot);
      trustedDER.len = mozilla::ArrayLength(addonsPublicRoot);
      break;

    case nsIX509CertDB::AddonsStageRoot:
      trustedDER.data = const_cast<uint8_t*>(addonsStageRoot);
      trustedDER.len = mozilla::ArrayLength(addonsStageRoot);
      break;

    case nsIX509CertDB::PrivilegedPackageRoot:
      trustedDER.data = const_cast<uint8_t*>(privilegedPackageRoot);
      trustedDER.len = mozilla::ArrayLength(privilegedPackageRoot);
      break;

    case nsIX509CertDB::DeveloperImportedRoot: {
      StaticMutexAutoLock lock(sMutex);
      if (!sDevImportedDERData) {
        MOZ_ASSERT(!NS_IsMainThread());
        nsCOMPtr<nsIFile> file(do_CreateInstance("@mozilla.org/file/local;1"));
        if (!file) {
          return NS_ERROR_FAILURE;
        }
        nsAutoCString path;
        Preferences::GetCString(kDevImportedDER, path);
        nsresult rv = file->InitWithNativePath(path);
        if (NS_FAILED(rv)) {
          return rv;
        }

        nsCOMPtr<nsIInputStream> inputStream;
        rv = NS_NewLocalFileInputStream(getter_AddRefs(inputStream), file, -1,
                                        -1, nsIFileInputStream::CLOSE_ON_EOF);
        if (NS_FAILED(rv)) {
          return rv;
        }

        uint64_t length;
        rv = inputStream->Available(&length);
        if (NS_FAILED(rv)) {
          return rv;
        }

        auto data = MakeUnique<char[]>(length);
        rv = inputStream->Read(data.get(), length, &sDevImportedDERLen);
        if (NS_FAILED(rv)) {
          return rv;
        }

        MOZ_ASSERT(length == sDevImportedDERLen);
        sDevImportedDERData.reset(
            BitwiseCast<unsigned char*, char*>(data.release()));
      }

      trustedDER.data = sDevImportedDERData.get();
      trustedDER.len = sDevImportedDERLen;
      break;
    }

    default:
      return NS_ERROR_INVALID_ARG;
  }

  mTrustedRoot.reset(CERT_NewTempCertificate(
      CERT_GetDefaultCertDB(), &trustedDER, nullptr, false, true));
  if (!mTrustedRoot) {
    return mozilla::psm::GetXPCOMFromNSSError(PR_GetError());
  }

  // If we're verifying add-ons signed by our production root, we want to make
  // sure a valid intermediate certificate is available for path building.
  // Merely holding this alive in memory makes it available for NSS to find in
  // AppTrustDomain::FindIssuer.
  if (trustedRoot == nsIX509CertDB::AddonsPublicRoot) {
    SECItem intermediateDER = {
        siBuffer,
        const_cast<uint8_t*>(addonsPublicIntermediate),
        static_cast<unsigned int>(
            mozilla::ArrayLength(addonsPublicIntermediate)),
    };
    mAddonsIntermediate.reset(CERT_NewTempCertificate(
        CERT_GetDefaultCertDB(), &intermediateDER, nullptr, false, true));
    if (!mAddonsIntermediate) {
      return mozilla::psm::GetXPCOMFromNSSError(PR_GetError());
    }
  }

  return NS_OK;
}

Result AppTrustDomain::FindIssuer(Input encodedIssuerName,
                                  IssuerChecker& checker, Time)

{
  MOZ_ASSERT(mTrustedRoot);
  if (!mTrustedRoot) {
    return Result::FATAL_ERROR_INVALID_STATE;
  }

  // TODO(bug 1035418): If/when mozilla::pkix relaxes the restriction that
  // FindIssuer must only pass certificates with a matching subject name to
  // checker.Check, we can stop using CERT_CreateSubjectCertList and instead
  // use logic like this:
  //
  // 1. First, try the trusted trust anchor.
  // 2. Secondly, iterate through the certificates that were stored in the CMS
  //    message, passing each one to checker.Check.
  SECItem encodedIssuerNameSECItem = UnsafeMapInputToSECItem(encodedIssuerName);
  UniqueCERTCertList candidates(CERT_CreateSubjectCertList(
      nullptr, CERT_GetDefaultCertDB(), &encodedIssuerNameSECItem, 0, false));
  if (candidates) {
    for (CERTCertListNode* n = CERT_LIST_HEAD(candidates);
         !CERT_LIST_END(n, candidates); n = CERT_LIST_NEXT(n)) {
      Input certDER;
      Result rv = certDER.Init(n->cert->derCert.data, n->cert->derCert.len);
      if (rv != Success) {
        continue;  // probably too big
      }

      bool keepGoing;
      rv = checker.Check(certDER, nullptr /*additionalNameConstraints*/,
                         keepGoing);
      if (rv != Success) {
        return rv;
      }
      if (!keepGoing) {
        break;
      }
    }
  }

  return Success;
}

Result AppTrustDomain::GetCertTrust(EndEntityOrCA endEntityOrCA,
                                    const CertPolicyId& policy,
                                    Input candidateCertDER,
                                    /*out*/ TrustLevel& trustLevel) {
  MOZ_ASSERT(policy.IsAnyPolicy());
  MOZ_ASSERT(mTrustedRoot);
  if (!policy.IsAnyPolicy()) {
    return Result::FATAL_ERROR_INVALID_ARGS;
  }
  if (!mTrustedRoot) {
    return Result::FATAL_ERROR_INVALID_STATE;
  }

  // Handle active distrust of the certificate.

  // XXX: This would be cleaner and more efficient if we could get the trust
  // information without constructing a CERTCertificate here, but NSS doesn't
  // expose it in any other easy-to-use fashion.
  SECItem candidateCertDERSECItem = UnsafeMapInputToSECItem(candidateCertDER);
  UniqueCERTCertificate candidateCert(CERT_NewTempCertificate(
      CERT_GetDefaultCertDB(), &candidateCertDERSECItem, nullptr, false, true));
  if (!candidateCert) {
    return MapPRErrorCodeToResult(PR_GetError());
  }

  CERTCertTrust trust;
  if (CERT_GetCertTrust(candidateCert.get(), &trust) == SECSuccess) {
    uint32_t flags = SEC_GET_TRUST_FLAGS(&trust, trustObjectSigning);

    // For DISTRUST, we use the CERTDB_TRUSTED or CERTDB_TRUSTED_CA bit,
    // because we can have active distrust for either type of cert. Note that
    // CERTDB_TERMINAL_RECORD means "stop trying to inherit trust" so if the
    // relevant trust bit isn't set then that means the cert must be considered
    // distrusted.
    uint32_t relevantTrustBit = endEntityOrCA == EndEntityOrCA::MustBeCA
                                    ? CERTDB_TRUSTED_CA
                                    : CERTDB_TRUSTED;
    if (((flags & (relevantTrustBit | CERTDB_TERMINAL_RECORD))) ==
        CERTDB_TERMINAL_RECORD) {
      trustLevel = TrustLevel::ActivelyDistrusted;
      return Success;
    }
  }

  // mTrustedRoot is the only trust anchor for this validation.
  if (CERT_CompareCerts(mTrustedRoot.get(), candidateCert.get())) {
    trustLevel = TrustLevel::TrustAnchor;
    return Success;
  }

  trustLevel = TrustLevel::InheritsTrust;
  return Success;
}

Result AppTrustDomain::DigestBuf(Input item, DigestAlgorithm digestAlg,
                                 /*out*/ uint8_t* digestBuf,
                                 size_t digestBufLen) {
  return DigestBufNSS(item, digestAlg, digestBuf, digestBufLen);
}

Result AppTrustDomain::CheckRevocation(EndEntityOrCA, const CertID&, Time,
                                       Duration,
                                       /*optional*/ const Input*,
                                       /*optional*/ const Input*) {
  // We don't currently do revocation checking. If we need to distrust an Apps
  // certificate, we will use the active distrust mechanism.
  return Success;
}

Result AppTrustDomain::IsChainValid(const DERArray& certChain, Time time,
                                    const CertPolicyId& requiredPolicy) {
  MOZ_ASSERT(requiredPolicy.IsAnyPolicy());
  SECStatus srv =
      ConstructCERTCertListFromReversedDERArray(certChain, mCertChain);
  if (srv != SECSuccess) {
    return MapPRErrorCodeToResult(PR_GetError());
  }
  return Success;
}

Result AppTrustDomain::CheckSignatureDigestAlgorithm(DigestAlgorithm,
                                                     EndEntityOrCA, Time) {
  // TODO: We should restrict signatures to SHA-256 or better.
  return Success;
}

Result AppTrustDomain::CheckRSAPublicKeyModulusSizeInBits(
    EndEntityOrCA /*endEntityOrCA*/, unsigned int modulusSizeInBits) {
  if (modulusSizeInBits < 2048u) {
    return Result::ERROR_INADEQUATE_KEY_SIZE;
  }
  return Success;
}

Result AppTrustDomain::VerifyRSAPKCS1SignedDigest(
    const SignedDigest& signedDigest, Input subjectPublicKeyInfo) {
  // TODO: We should restrict signatures to SHA-256 or better.
  return VerifyRSAPKCS1SignedDigestNSS(signedDigest, subjectPublicKeyInfo,
                                       mPinArg);
}

Result AppTrustDomain::CheckECDSACurveIsAcceptable(
    EndEntityOrCA /*endEntityOrCA*/, NamedCurve curve) {
  switch (curve) {
    case NamedCurve::secp256r1:  // fall through
    case NamedCurve::secp384r1:  // fall through
    case NamedCurve::secp521r1:
      return Success;
  }

  return Result::ERROR_UNSUPPORTED_ELLIPTIC_CURVE;
}

Result AppTrustDomain::VerifyECDSASignedDigest(const SignedDigest& signedDigest,
                                               Input subjectPublicKeyInfo) {
  return VerifyECDSASignedDigestNSS(signedDigest, subjectPublicKeyInfo,
                                    mPinArg);
}

Result AppTrustDomain::CheckValidityIsAcceptable(
    Time /*notBefore*/, Time /*notAfter*/, EndEntityOrCA /*endEntityOrCA*/,
    KeyPurposeId /*keyPurpose*/) {
  return Success;
}

Result AppTrustDomain::NetscapeStepUpMatchesServerAuth(Time /*notBefore*/,
                                                       /*out*/ bool& matches) {
  matches = false;
  return Success;
}

void AppTrustDomain::NoteAuxiliaryExtension(AuxiliaryExtension /*extension*/,
                                            Input /*extensionData*/) {}

}  // namespace psm
}  // namespace mozilla