Quelle SRIMetadata.cpp Sprache: C

/* -*- 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 "SRIMetadata.h"

#include "hasht.h"
#include "mozilla/Logging.h"
#include "nsICryptoHash.h"

static mozilla::LogModule* GetSriMetadataLog() {
  static mozilla::LazyLogModule gSriMetadataPRLog("SRIMetadata");
  return gSriMetadataPRLog;
}

#define SRIMETADATALOG(args) \
  MOZ_LOG(GetSriMetadataLog(), mozilla::LogLevel::Debug, args)
#define SRIMETADATAERROR(args) \
  MOZ_LOG(GetSriMetadataLog(), mozilla::LogLevel::Error, args)

namespace mozilla::dom {

SRIMetadata::SRIMetadata(const nsACString& aToken)
    : mAlgorithmType(SRIMetadata::UNKNOWN_ALGORITHM), mEmpty(false) {
  MOZ_ASSERT(!aToken.IsEmpty());  // callers should check this first

  SRIMETADATALOG(("SRIMetadata::SRIMetadata, aToken='%s'",
                  PromiseFlatCString(aToken).get()));

  int32_t hyphen = aToken.FindChar('-');
  if (hyphen == -1) {
    SRIMETADATAERROR(("SRIMetadata::SRIMetadata, invalid (no hyphen)"));
    return;  // invalid metadata
  }

  // split the token into its components
  mAlgorithm = Substring(aToken, 0, hyphen);
  uint32_t hashStart = hyphen + 1;
  if (hashStart >= aToken.Length()) {
    SRIMETADATAERROR(("SRIMetadata::SRIMetadata, invalid (missing digest)"));
    return;  // invalid metadata
  }
  int32_t question = aToken.FindChar('?');
  if (question == -1) {
    mHashes.AppendElement(
        Substring(aToken, hashStart, aToken.Length() - hashStart));
  } else {
    MOZ_ASSERT(question > 0);
    if (static_cast<uint32_t>(question) <= hashStart) {
      SRIMETADATAERROR(
          ("SRIMetadata::SRIMetadata, invalid (options w/o digest)"));
      return;  // invalid metadata
    }
    mHashes.AppendElement(Substring(aToken, hashStart, question - hashStart));
  }

  if (mAlgorithm.EqualsLiteral("sha256")) {
    mAlgorithmType = nsICryptoHash::SHA256;
  } else if (mAlgorithm.EqualsLiteral("sha384")) {
    mAlgorithmType = nsICryptoHash::SHA384;
  } else if (mAlgorithm.EqualsLiteral("sha512")) {
    mAlgorithmType = nsICryptoHash::SHA512;
  }

  SRIMETADATALOG(("SRIMetadata::SRIMetadata, hash='%s'; alg='%s'",
                  mHashes[0].get(), mAlgorithm.get()));
}

bool SRIMetadata::operator<(const SRIMetadata& aOther) const {
  static_assert(nsICryptoHash::SHA256 < nsICryptoHash::SHA384,
                "We rely on the order indicating relative alg strength");
  static_assert(nsICryptoHash::SHA384 < nsICryptoHash::SHA512,
                "We rely on the order indicating relative alg strength");
  MOZ_ASSERT(mAlgorithmType == SRIMetadata::UNKNOWN_ALGORITHM ||
             mAlgorithmType == nsICryptoHash::SHA256 ||
             mAlgorithmType == nsICryptoHash::SHA384 ||
             mAlgorithmType == nsICryptoHash::SHA512);
  MOZ_ASSERT(aOther.mAlgorithmType == SRIMetadata::UNKNOWN_ALGORITHM ||
             aOther.mAlgorithmType == nsICryptoHash::SHA256 ||
             aOther.mAlgorithmType == nsICryptoHash::SHA384 ||
             aOther.mAlgorithmType == nsICryptoHash::SHA512);

  if (mEmpty) {
    SRIMETADATALOG(("SRIMetadata::operator<, first metadata is empty"));
    return true;  // anything beats the empty metadata (incl. invalid ones)
  }

  SRIMETADATALOG(("SRIMetadata::operator<, alg1='%d'; alg2='%d'",
                  mAlgorithmType, aOther.mAlgorithmType));
  return (mAlgorithmType < aOther.mAlgorithmType);
}

bool SRIMetadata::operator>(const SRIMetadata& aOther) const {
  MOZ_ASSERT(false);
  return false;
}

SRIMetadata& SRIMetadata::operator+=(const SRIMetadata& aOther) {
  MOZ_ASSERT(!aOther.IsEmpty() && !IsEmpty());
  MOZ_ASSERT(aOther.IsValid() && IsValid());
  MOZ_ASSERT(mAlgorithmType == aOther.mAlgorithmType);

  // We only pull in the first element of the other metadata
  MOZ_ASSERT(aOther.mHashes.Length() == 1);
  if (mHashes.Length() < SRIMetadata::MAX_ALTERNATE_HASHES) {
    SRIMETADATALOG((
        "SRIMetadata::operator+=, appending another '%s' hash (new length=%zu)",
        mAlgorithm.get(), mHashes.Length()));
    mHashes.AppendElement(aOther.mHashes[0]);
  }

  MOZ_ASSERT(mHashes.Length() > 1);
  MOZ_ASSERT(mHashes.Length() <= SRIMetadata::MAX_ALTERNATE_HASHES);
  return *this;
}

bool SRIMetadata::operator==(const SRIMetadata& aOther) const {
  if (IsEmpty() || !IsValid()) {
    return false;
  }
  return mAlgorithmType == aOther.mAlgorithmType;
}

void SRIMetadata::GetHash(uint32_t aIndex, nsCString* outHash) const {
  MOZ_ASSERT(aIndex < SRIMetadata::MAX_ALTERNATE_HASHES);
  if (NS_WARN_IF(aIndex >= mHashes.Length())) {
    *outHash = nullptr;
    return;
  }
  *outHash = mHashes[aIndex];
}

void SRIMetadata::GetHashType(int8_t* outType, uint32_t* outLength) const {
  // these constants are defined in security/nss/lib/util/hasht.h and
  // netwerk/base/public/nsICryptoHash.idl
  switch (mAlgorithmType) {
    case nsICryptoHash::SHA256:
      *outLength = SHA256_LENGTH;
      break;
    case nsICryptoHash::SHA384:
      *outLength = SHA384_LENGTH;
      break;
    case nsICryptoHash::SHA512:
      *outLength = SHA512_LENGTH;
      break;
    default:
      *outLength = 0;
  }
  *outType = mAlgorithmType;
}

bool SRIMetadata::CanTrustBeDelegatedTo(const SRIMetadata& aOther) const {
  if (IsEmpty()) {
    // No integrity requirements enforced, just let go.
    return true;
  }

  if (aOther.IsEmpty()) {
    // This metadata requires a check and the other has none, can't delegate.
    return false;
  }

  if (mAlgorithmType != aOther.mAlgorithmType) {
    // They must use the same hash algorithm.
    return false;
  }

  // They must be completely identical, except for the order of hashes.
  // We don't know which hash is the one passing eventually the check, so only
  // option is to require this metadata to contain the same set of hashes as the
  // one we want to delegate the trust to.
  if (mHashes.Length() != aOther.mHashes.Length()) {
    return false;
  }

  for (const auto& hash : mHashes) {
    if (!aOther.mHashes.Contains(hash)) {
      return false;
    }
  }

  return true;
}

}  // namespace mozilla::dom

quality98%

¤ Dauer der Verarbeitung: 0.12 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.