gecko-dev/security/certverifier/CTSerialization.cpp
Stephanie Ouillon 73e9f686e8 Bug 1343202 - Utility function for decoding an InclusionProof structure; r=ckerschb,keeler
MozReview-Commit-ID: 1x2Cwan8nLL

--HG--
extra : rebase_source : 079a8945f4d04be06dd99b776246d9b96930613a
2017-08-18 09:50:49 +02:00

552 lines
16 KiB
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 "CTSerialization.h"
#include "CTUtils.h"
#include <stdint.h>
#include "mozilla/Assertions.h"
#include "mozilla/Move.h"
#include "mozilla/TypeTraits.h"
namespace mozilla { namespace ct {
using namespace mozilla::pkix;
typedef mozilla::pkix::Result Result;
// Note: length is always specified in bytes.
// Signed Certificate Timestamp (SCT) Version length
static const size_t kVersionLength = 1;
// Members of a V1 SCT
static const size_t kLogIdLength = 32;
static const size_t kTimestampLength = 8;
static const size_t kExtensionsLengthBytes = 2;
static const size_t kHashAlgorithmLength = 1;
static const size_t kSigAlgorithmLength = 1;
static const size_t kSignatureLengthBytes = 2;
// Members of the digitally-signed struct of a V1 SCT
static const size_t kSignatureTypeLength = 1;
static const size_t kLogEntryTypeLength = 2;
static const size_t kAsn1CertificateLengthBytes = 3;
static const size_t kTbsCertificateLengthBytes = 3;
static const size_t kSCTListLengthBytes = 2;
static const size_t kSerializedSCTLengthBytes = 2;
// Members of digitally-signed struct of a STH
static const size_t kTreeSizeLength = 8;
// Length of sha256RootHash buffer of SignedTreeHead
static const size_t kSthRootHashLength = 32;
enum class SignatureType {
CertificateTimestamp = 0,
TreeHash = 1,
};
// Reads a TLS-encoded variable length unsigned integer from |in|.
// The integer is expected to be in big-endian order, which is used by TLS.
// Note: does not check if the output parameter overflows while reading.
// |length| indicates the size (in bytes) of the serialized integer.
static Result
UncheckedReadUint(size_t length, Reader& in, uint64_t& out)
{
uint64_t result = 0;
for (size_t i = 0; i < length; ++i) {
uint8_t value;
Result rv = in.Read(value);
if (rv != Success) {
return rv;
}
result = (result << 8) | value;
}
out = result;
return Success;
}
// Performs overflow sanity checks and calls UncheckedReadUint.
template <size_t length, typename T>
Result
ReadUint(Reader& in, T& out)
{
uint64_t value;
static_assert(mozilla::IsUnsigned<T>::value, "T must be unsigned");
static_assert(length <= 8, "At most 8 byte integers can be read");
static_assert(sizeof(T) >= length, "T must be able to hold <length> bytes");
Result rv = UncheckedReadUint(length, in, value);
if (rv != Success) {
return rv;
}
out = static_cast<T>(value);
return Success;
}
// Reads |length| bytes from |in|.
static Result
ReadFixedBytes(size_t length, Reader& in, Input& out)
{
return in.Skip(length, out);
}
// Reads a length-prefixed variable amount of bytes from |in|, updating |out|
// on success. |prefixLength| indicates the number of bytes needed to represent
// the length.
template <size_t prefixLength>
Result
ReadVariableBytes(Reader& in, Input& out)
{
size_t length;
Result rv = ReadUint<prefixLength>(in, length);
if (rv != Success) {
return rv;
}
return ReadFixedBytes(length, in, out);
}
// Reads a serialized hash algorithm.
static Result
ReadHashAlgorithm(Reader& in, DigitallySigned::HashAlgorithm& out)
{
unsigned int value;
Result rv = ReadUint<kHashAlgorithmLength>(in, value);
if (rv != Success) {
return rv;
}
DigitallySigned::HashAlgorithm algo =
static_cast<DigitallySigned::HashAlgorithm>(value);
switch (algo) {
case DigitallySigned::HashAlgorithm::None:
case DigitallySigned::HashAlgorithm::MD5:
case DigitallySigned::HashAlgorithm::SHA1:
case DigitallySigned::HashAlgorithm::SHA224:
case DigitallySigned::HashAlgorithm::SHA256:
case DigitallySigned::HashAlgorithm::SHA384:
case DigitallySigned::HashAlgorithm::SHA512:
out = algo;
return Success;
}
return Result::ERROR_BAD_DER;
}
// Reads a serialized signature algorithm.
static Result
ReadSignatureAlgorithm(Reader& in, DigitallySigned::SignatureAlgorithm& out)
{
unsigned int value;
Result rv = ReadUint<kSigAlgorithmLength>(in, value);
if (rv != Success) {
return rv;
}
DigitallySigned::SignatureAlgorithm algo =
static_cast<DigitallySigned::SignatureAlgorithm>(value);
switch (algo) {
case DigitallySigned::SignatureAlgorithm::Anonymous:
case DigitallySigned::SignatureAlgorithm::RSA:
case DigitallySigned::SignatureAlgorithm::DSA:
case DigitallySigned::SignatureAlgorithm::ECDSA:
out = algo;
return Success;
}
return Result::ERROR_BAD_DER;
}
// Reads a serialized version enum.
static Result
ReadVersion(Reader& in, SignedCertificateTimestamp::Version& out)
{
unsigned int value;
Result rv = ReadUint<kVersionLength>(in, value);
if (rv != Success) {
return rv;
}
SignedCertificateTimestamp::Version version =
static_cast<SignedCertificateTimestamp::Version>(value);
switch (version) {
case SignedCertificateTimestamp::Version::V1:
out = version;
return Success;
}
return Result::ERROR_BAD_DER;
}
// Writes a TLS-encoded variable length unsigned integer to |output|.
// Note: range/overflow checks are not performed on the input parameters.
// |length| indicates the size (in bytes) of the integer to be written.
// |value| the value itself to be written.
static Result
UncheckedWriteUint(size_t length, uint64_t value, Buffer& output)
{
if (!output.reserve(length + output.length())) {
return Result::FATAL_ERROR_NO_MEMORY;
}
for (; length > 0; --length) {
uint8_t nextByte = (value >> ((length - 1) * 8)) & 0xFF;
output.infallibleAppend(nextByte);
}
return Success;
}
// Performs sanity checks on T and calls UncheckedWriteUint.
template <size_t length, typename T>
static inline Result
WriteUint(T value, Buffer& output)
{
static_assert(length <= 8, "At most 8 byte integers can be written");
static_assert(sizeof(T) >= length, "T must be able to hold <length> bytes");
if (mozilla::IsSigned<T>::value) {
// We accept signed integer types assuming the actual value is non-negative.
if (value < 0) {
return Result::FATAL_ERROR_INVALID_ARGS;
}
}
if (sizeof(T) > length) {
// We allow the value variable to take more bytes than is written,
// but the unwritten bytes must be zero.
// Note: when "sizeof(T) == length" holds, "value >> (length * 8)" is
// undefined since the shift is too big. On some compilers, this would
// produce a warning even though the actual code is unreachable.
if (value >> (length * 8 - 1) > 1) {
return Result::FATAL_ERROR_INVALID_ARGS;
}
}
return UncheckedWriteUint(length, static_cast<uint64_t>(value), output);
}
// Writes an array to |output| from |input|.
// Should be used in one of two cases:
// * The length of |input| has already been encoded into the |output| stream.
// * The length of |input| is fixed and the reader is expected to specify that
// length when reading.
// If the length of |input| is dynamic and data is expected to follow it,
// WriteVariableBytes must be used.
static Result
WriteEncodedBytes(Input input, Buffer& output)
{
if (!output.append(input.UnsafeGetData(), input.GetLength())) {
return Result::FATAL_ERROR_NO_MEMORY;
}
return Success;
}
// Same as above, but the source data is in a Buffer.
static Result
WriteEncodedBytes(const Buffer& source, Buffer& output)
{
if (!output.appendAll(source)) {
return Result::FATAL_ERROR_NO_MEMORY;
}
return Success;
}
// A variable-length byte array is prefixed by its length when serialized.
// This writes the length prefix.
// |prefixLength| indicates the number of bytes needed to represent the length.
// |dataLength| is the length of the byte array following the prefix.
// Fails if |dataLength| is more than 2^|prefixLength| - 1.
template <size_t prefixLength>
static Result
WriteVariableBytesPrefix(size_t dataLength, Buffer& output)
{
const size_t maxAllowedInputSize =
static_cast<size_t>(((1 << (prefixLength * 8)) - 1));
if (dataLength > maxAllowedInputSize) {
return Result::FATAL_ERROR_INVALID_ARGS;
}
return WriteUint<prefixLength>(dataLength, output);
}
// Writes a variable-length array to |output|.
// |prefixLength| indicates the number of bytes needed to represent the length.
// |input| is the array itself.
// Fails if the size of |input| is more than 2^|prefixLength| - 1.
template <size_t prefixLength>
static Result
WriteVariableBytes(Input input, Buffer& output)
{
Result rv = WriteVariableBytesPrefix<prefixLength>(input.GetLength(), output);
if (rv != Success) {
return rv;
}
return WriteEncodedBytes(input, output);
}
// Same as above, but the source data is in a Buffer.
template <size_t prefixLength>
static Result
WriteVariableBytes(const Buffer& source, Buffer& output)
{
Input input;
Result rv = BufferToInput(source, input);
if (rv != Success) {
return rv;
}
return WriteVariableBytes<prefixLength>(input, output);
}
// Writes a LogEntry of type X.509 cert to |output|.
// |input| is the LogEntry containing the certificate.
static Result
EncodeAsn1CertLogEntry(const LogEntry& entry, Buffer& output)
{
return WriteVariableBytes<kAsn1CertificateLengthBytes>(entry.leafCertificate,
output);
}
// Writes a LogEntry of type PreCertificate to |output|.
// |input| is the LogEntry containing the TBSCertificate and issuer key hash.
static Result
EncodePrecertLogEntry(const LogEntry& entry, Buffer& output)
{
if (entry.issuerKeyHash.length() != kLogIdLength) {
return Result::FATAL_ERROR_INVALID_ARGS;
}
Result rv = WriteEncodedBytes(entry.issuerKeyHash, output);
if (rv != Success) {
return rv;
}
return WriteVariableBytes<kTbsCertificateLengthBytes>(entry.tbsCertificate,
output);
}
Result
EncodeDigitallySigned(const DigitallySigned& data, Buffer& output)
{
Result rv = WriteUint<kHashAlgorithmLength>(
static_cast<unsigned int>(data.hashAlgorithm), output);
if (rv != Success) {
return rv;
}
rv = WriteUint<kSigAlgorithmLength>(
static_cast<unsigned int>(data.signatureAlgorithm), output);
if (rv != Success) {
return rv;
}
return WriteVariableBytes<kSignatureLengthBytes>(data.signatureData, output);
}
Result
DecodeDigitallySigned(Reader& reader, DigitallySigned& output)
{
DigitallySigned result;
Result rv = ReadHashAlgorithm(reader, result.hashAlgorithm);
if (rv != Success) {
return rv;
}
rv = ReadSignatureAlgorithm(reader, result.signatureAlgorithm);
if (rv != Success) {
return rv;
}
Input signatureData;
rv = ReadVariableBytes<kSignatureLengthBytes>(reader, signatureData);
if (rv != Success) {
return rv;
}
rv = InputToBuffer(signatureData, result.signatureData);
if (rv != Success) {
return rv;
}
output = Move(result);
return Success;
}
Result
EncodeLogEntry(const LogEntry& entry, Buffer& output)
{
Result rv = WriteUint<kLogEntryTypeLength>(
static_cast<unsigned int>(entry.type), output);
if (rv != Success) {
return rv;
}
switch (entry.type) {
case LogEntry::Type::X509:
return EncodeAsn1CertLogEntry(entry, output);
case LogEntry::Type::Precert:
return EncodePrecertLogEntry(entry, output);
default:
MOZ_ASSERT_UNREACHABLE("Unexpected LogEntry type");
}
return Result::ERROR_BAD_DER;
}
static Result
WriteTimeSinceEpoch(uint64_t timestamp, Buffer& output)
{
return WriteUint<kTimestampLength>(timestamp, output);
}
Result
EncodeV1SCTSignedData(uint64_t timestamp, Input serializedLogEntry,
Input extensions, Buffer& output)
{
Result rv = WriteUint<kVersionLength>(static_cast<unsigned int>(
SignedCertificateTimestamp::Version::V1), output);
if (rv != Success) {
return rv;
}
rv = WriteUint<kSignatureTypeLength>(static_cast<unsigned int>(
SignatureType::CertificateTimestamp), output);
if (rv != Success) {
return rv;
}
rv = WriteTimeSinceEpoch(timestamp, output);
if (rv != Success) {
return rv;
}
// NOTE: serializedLogEntry must already be serialized and contain the
// length as the prefix.
rv = WriteEncodedBytes(serializedLogEntry, output);
if (rv != Success) {
return rv;
}
return WriteVariableBytes<kExtensionsLengthBytes>(extensions, output);
}
Result
EncodeTreeHeadSignature(const SignedTreeHead& signedTreeHead,
Buffer& output)
{
Result rv = WriteUint<kVersionLength>(
static_cast<unsigned int>(signedTreeHead.version), output);
if (rv != Success) {
return rv;
}
rv = WriteUint<kSignatureTypeLength>(
static_cast<unsigned int>(SignatureType::TreeHash), output);
if (rv != Success) {
return rv;
}
rv = WriteTimeSinceEpoch(signedTreeHead.timestamp, output);
if (rv != Success) {
return rv;
}
rv = WriteUint<kTreeSizeLength>(signedTreeHead.treeSize, output);
if (rv != Success) {
return rv;
}
if (signedTreeHead.sha256RootHash.length() != kSthRootHashLength) {
return Result::FATAL_ERROR_INVALID_ARGS;
}
return WriteEncodedBytes(signedTreeHead.sha256RootHash, output);
}
Result
DecodeSCTList(Input input, Reader& listReader)
{
Reader inputReader(input);
Input listData;
Result rv = ReadVariableBytes<kSCTListLengthBytes>(inputReader, listData);
if (rv != Success) {
return rv;
}
return listReader.Init(listData);
}
Result
ReadSCTListItem(Reader& listReader, Input& output)
{
if (listReader.AtEnd()) {
return Result::FATAL_ERROR_INVALID_ARGS;
}
Result rv = ReadVariableBytes<kSerializedSCTLengthBytes>(listReader, output);
if (rv != Success) {
return rv;
}
if (output.GetLength() == 0) {
return Result::ERROR_BAD_DER;
}
return Success;
}
Result
DecodeSignedCertificateTimestamp(Reader& reader,
SignedCertificateTimestamp& output)
{
SignedCertificateTimestamp result;
Result rv = ReadVersion(reader, result.version);
if (rv != Success) {
return rv;
}
uint64_t timestamp;
Input logId;
Input extensions;
rv = ReadFixedBytes(kLogIdLength, reader, logId);
if (rv != Success) {
return rv;
}
rv = ReadUint<kTimestampLength>(reader, timestamp);
if (rv != Success) {
return rv;
}
rv = ReadVariableBytes<kExtensionsLengthBytes>(reader, extensions);
if (rv != Success) {
return rv;
}
rv = DecodeDigitallySigned(reader, result.signature);
if (rv != Success) {
return rv;
}
rv = InputToBuffer(logId, result.logId);
if (rv != Success) {
return rv;
}
rv = InputToBuffer(extensions, result.extensions);
if (rv != Success) {
return rv;
}
result.timestamp = timestamp;
output = Move(result);
return Success;
}
Result
EncodeSCTList(const Vector<pkix::Input>& scts, Buffer& output)
{
// Find out the total size of the SCT list to be written so we can
// write the prefix for the list before writing its contents.
size_t sctListLength = 0;
for (auto& sct : scts) {
sctListLength +=
/* data size */ sct.GetLength() +
/* length prefix size */ kSerializedSCTLengthBytes;
}
if (!output.reserve(kSCTListLengthBytes + sctListLength)) {
return Result::FATAL_ERROR_NO_MEMORY;
}
// Write the prefix for the SCT list.
Result rv = WriteVariableBytesPrefix<kSCTListLengthBytes>(sctListLength,
output);
if (rv != Success) {
return rv;
}
// Now write each SCT from the list.
for (auto& sct : scts) {
rv = WriteVariableBytes<kSerializedSCTLengthBytes>(sct, output);
if (rv != Success) {
return rv;
}
}
return Success;
}
} } // namespace mozilla::ct