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Harden CDoc2 fetchKey checks #1444

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Harden CDoc2 fetchKey checks #1444

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43 changes: 36 additions & 7 deletions client/CDocSupport.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@
#include <QtCore/QBuffer>
#include <QtCore/QJsonDocument>
#include <QtCore/QJsonObject>
#include <QtCore/QJsonParseError>
#include <QtCore/QtEndian>
#include <QtCore/QTemporaryFile>
#include <QtCore/QUrlQuery>
Expand Down Expand Up @@ -314,15 +315,21 @@ libcdoc::result_t DDNetworkBackend::sendKey(
libcdoc::result_t
DDNetworkBackend::fetchKey(std::vector<uint8_t> &result, const std::string &url, const std::string &transaction_id)
{
QNetworkRequest req(QStringLiteral("%1/key-capsules/%2").arg(QString::fromStdString(url), QLatin1String(transaction_id.c_str())));
if(transaction_id.empty()) {
last_error = "Missing key-capsule transaction identifier";
return BACKEND_ERROR;
}
QByteArray requestUrl = QByteArray::fromStdString(url + "/key-capsules/");
requestUrl += QByteArray::fromStdString(transaction_id).toPercentEncoding();
QNetworkRequest req(QUrl::fromEncoded(requestUrl, QUrl::StrictMode));
req.setHeader(QNetworkRequest::ContentTypeHeader, QStringLiteral("application/json"));
if(!checkConnection()) {
last_error = "No connection";
return BACKEND_ERROR;
}

TokenData auth = qApp->signer()->tokenauth();
auto val = QCryptoBackend::getBackend(qApp->signer()->tokenauth());
auto val = QCryptoBackend::getBackend(auth);
if (!val)
return getDecryptStatus(val.error());
std::unique_ptr<QCryptoBackend> backend(val.value());
Expand All @@ -333,19 +340,41 @@ DDNetworkBackend::fetchKey(std::vector<uint8_t> &result, const std::string &url,
return BACKEND_ERROR;
}
QScopedPointer<QNetworkAccessManager,QScopedPointerDeleteLater> nam(
CheckConnection::setupNAM(req, qApp->signer()->tokenauth().cert(), authKey, Settings::CDOC2_GET_CERT));
CheckConnection::setupNAM(req, auth.cert(), authKey, Settings::CDOC2_GET_CERT));
QEventLoop e;
QNetworkReply *reply = nam->get(req);
connect(reply, &QNetworkReply::finished, &e, &QEventLoop::quit);
e.exec();

if(reply->error() != QNetworkReply::NoError && reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt() != 201) {
if(reply->error() != QNetworkReply::NoError) {
last_error = reply->errorString().toStdString();
return BACKEND_ERROR;
}
QJsonObject json = QJsonDocument::fromJson(reply->readAll()).object();
QByteArray key_material = QByteArray::fromBase64(json.value(QLatin1String("ephemeral_key_material")).toString().toLatin1());
result.assign(key_material.cbegin(), key_material.cend());
const int httpStatus = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
if(httpStatus != 200) {
last_error = QStringLiteral("Key-capsule request failed with HTTP status %1").arg(httpStatus).toStdString();
return BACKEND_ERROR;
}

QJsonParseError parseError;
const QJsonDocument document = QJsonDocument::fromJson(reply->readAll(), &parseError);
if(parseError.error != QJsonParseError::NoError || !document.isObject()) {
last_error = "Invalid key-capsule JSON response";
return BACKEND_ERROR;
}
const QJsonValue keyValue = document.object().value(QLatin1String("ephemeral_key_material"));
if(!keyValue.isString()) {
last_error = "Missing key material in key-capsule response";
return BACKEND_ERROR;
}
const auto decoded = QByteArray::fromBase64Encoding(
keyValue.toString().toLatin1(), QByteArray::AbortOnBase64DecodingErrors);
static constexpr qsizetype MAX_KEY_MATERIAL_SIZE = 16 * 1024;
if(!decoded || decoded.decoded.isEmpty() || decoded.decoded.size() > MAX_KEY_MATERIAL_SIZE) {
last_error = "Invalid key material in key-capsule response";
return BACKEND_ERROR;
}
result.assign(decoded.decoded.cbegin(), decoded.decoded.cend());

crypto.setBackend(std::move(backend));

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