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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 "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 {
namespace 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 SRI requires a check and the other has none, can't delegate.
return false;
}
if (mAlgorithmType < aOther.mAlgorithmType) {
// The other SRI is stronger than this one, we can (have to) delegate trust
// to it.
return true;
}
if (mAlgorithmType > aOther.mAlgorithmType) {
// This SRI is stronger than the other, we can't delegate the trust.
return false;
}
for (const auto& hash : mHashes) {
if (!aOther.mHashes.Contains(hash)) {
// Both SRIs must be completely identical. We don't know which hash is
// the one passing eventually the check, so only option is to require this
// SRI to contain the same set of hashes as the one we want to delegate
// the trust to.
return false;
}
}
return true;
}
} // namespace dom
} // namespace mozilla