File indexing completed on 2024-04-28 16:45:13

 /*
     SPDX-FileCopyrightText: 2020 David Edmundson <davidedmundson@kde.org>
 
     SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
 */
 
 #include "pamauthenticator.h"
 
 #include <QDebug>
 #include <QEventLoop>
 #include <QMetaMethod>
 #include <security/pam_appl.h>
 
 #include "kscreenlocker_greet_logging.h"
 
 class PamWorker : public QObject
 {
     Q_OBJECT
 public:
     PamWorker();
     ~PamWorker();
     void start(const QString &service, const QString &user);
     void authenticate();
 
 Q_SIGNALS:
     void busyChanged(bool busy);
     void promptForSecret(const QString &msg);
     void prompt(const QString &msg);
     void infoMessage(const QString &msg);
     void errorMessage(const QString &msg);
     void failed();
     void succeeded();
 
     // internal
     void promptResponseReceived(const QByteArray &prompt);
     void cancelled();
 
 private:
     static int converse(int n, const struct pam_message **msg, struct pam_response **resp, void *data);
 
     pam_handle_t *m_handle = nullptr; //< the actual PAM handle
     struct pam_conv m_conv;
 
     bool m_inAuthenticate = false;
     int m_result;
 };
 
 int PamWorker::converse(int n, const struct pam_message **msg, struct pam_response **resp, void *data)
 {
     PamWorker *c = static_cast<PamWorker *>(data);
 
     if (!resp) {
         return PAM_BUF_ERR;
     }
 
     *resp = (struct pam_response *)calloc(n, sizeof(struct pam_response));
 
     for (int i = 0; i < n; i++) {
         bool isSecret = false;
         switch (msg[i]->msg_style) {
         case PAM_PROMPT_ECHO_OFF: {
             isSecret = true;
             Q_FALLTHROUGH();
         case PAM_PROMPT_ECHO_ON:
             Q_EMIT c->busyChanged(false);
 
             const QString prompt = QString::fromLocal8Bit(msg[i]->msg);
             if (isSecret) {
                 Q_EMIT c->promptForSecret(prompt);
             } else {
                 Q_EMIT c->prompt(prompt);
             }
 
             QByteArray response;
             QEventLoop e;
             QObject::connect(c, &PamWorker::promptResponseReceived, &e, [&](const QByteArray &_response) {
                 response = _response;
                 e.exit(0);
             });
             QObject::connect(c, &PamWorker::cancelled, &e, [&]() {
                 e.exit(PAM_CONV_ERR);
             });
 
             int rc = e.exec();
             if (rc != 0) {
                 return rc;
             }
 
             Q_EMIT c->busyChanged(true);
 
             resp[i]->resp = (char *)malloc(response.length() + 1);
             // on error, get rid of everything
             if (!resp[i]->resp) {
                 for (int j = 0; j < n; j++) {
                     free(resp[i]->resp);
                     resp[i]->resp = nullptr;
                 }
                 free(*resp);
                 *resp = nullptr;
                 return PAM_BUF_ERR;
             }
 
             memcpy(resp[i]->resp, response.constData(), response.length());
             resp[i]->resp[response.length()] = '\0';
 
             break;
         }
         case PAM_ERROR_MSG:
             qCDebug(KSCREENLOCKER_GREET) << QString::fromLocal8Bit(msg[i]->msg);
             Q_EMIT c->errorMessage(QString::fromLocal8Bit(msg[i]->msg));
             break;
         case PAM_TEXT_INFO:
             // if there's only the info message, let's predict the prompts too
             qCDebug(KSCREENLOCKER_GREET) << QString::fromLocal8Bit(msg[i]->msg);
             Q_EMIT c->infoMessage(QString::fromLocal8Bit(msg[i]->msg));
         default:
             break;
         }
     }
 
     return PAM_SUCCESS;
 }
 
 PamWorker::PamWorker()
     : QObject(nullptr)
 {
     m_conv = {&PamWorker::converse, this};
 }
 
 PamWorker::~PamWorker()
 {
     if (m_handle) {
         pam_end(m_handle, PAM_SUCCESS);
     }
 }
 
 void PamWorker::authenticate()
 {
     if (m_inAuthenticate) {
         return;
     }
     m_inAuthenticate = true;
     qCDebug(KSCREENLOCKER_GREET) << "Start auth";
     int rc = pam_authenticate(m_handle, 0); // PAM_SILENT);
     qCDebug(KSCREENLOCKER_GREET) << "Auth done RC" << rc;
 
     Q_EMIT busyChanged(false);
 
     if (rc == PAM_SUCCESS) {
         rc = pam_setcred(m_handle, PAM_REFRESH_CRED);
         /* ignore errors on refresh credentials. If this did not work we use the old ones. */
         Q_EMIT succeeded();
     } else {
         Q_EMIT failed();
     }
     m_inAuthenticate = false;
 }
 
 static void fail_delay(int retval, unsigned usec_delay, void *appdata_ptr)
 {
     Q_UNUSED(retval);
     Q_UNUSED(usec_delay);
     Q_UNUSED(appdata_ptr);
 }
 
 void PamWorker::start(const QString &service, const QString &user)
 {
     if (user.isEmpty())
         m_result = pam_start(qPrintable(service), nullptr, &m_conv, &m_handle);
     else
         m_result = pam_start(qPrintable(service), qPrintable(user), &m_conv, &m_handle);
 
     // get errors quicker
 #ifdef PAM_FAIL_DELAY
     pam_set_item(m_handle, PAM_FAIL_DELAY, (void *)fail_delay);
 #endif
 
     if (m_result != PAM_SUCCESS) {
         qCWarning(KSCREENLOCKER_GREET) << "[PAM] start" << pam_strerror(m_handle, m_result);
         return;
     } else {
         qCDebug(KSCREENLOCKER_GREET) << "[PAM] Starting...";
     }
 }
 
 PamAuthenticator::PamAuthenticator(const QString &service, const QString &user, QObject *parent)
     : QObject(parent)
     , m_signalsToMembers({
           {QMetaMethod::fromSignal(&PamAuthenticator::prompt), m_prompt},
           {QMetaMethod::fromSignal(&PamAuthenticator::promptForSecret), m_promptForSecret},
           {QMetaMethod::fromSignal(&PamAuthenticator::infoMessage), m_infoMessage},
           {QMetaMethod::fromSignal(&PamAuthenticator::errorMessage), m_errorMessage},
       })
 {
     d = new PamWorker;
 
     d->moveToThread(&m_thread);
 
     connect(&m_thread, &QThread::finished, d, &QObject::deleteLater);
 
     connect(d, &PamWorker::busyChanged, this, &PamAuthenticator::setBusy);
     connect(d, &PamWorker::prompt, this, [this](const QString &msg) {
         m_prompt = msg;
         Q_EMIT prompt(msg);
     });
     connect(d, &PamWorker::promptForSecret, this, [this](const QString &msg) {
         m_promptForSecret = msg;
         Q_EMIT promptForSecret(msg);
     });
     connect(d, &PamWorker::infoMessage, this, [this](const QString &msg) {
         m_infoMessage = msg;
         Q_EMIT infoMessage(msg);
     });
     connect(d, &PamWorker::errorMessage, this, [this](const QString &msg) {
         m_errorMessage = msg;
         Q_EMIT errorMessage(msg);
     });
 
     connect(d, &PamWorker::succeeded, this, [this]() {
         m_unlocked = true;
         Q_EMIT succeeded();
     });
     // Failed is not a persistent state. When a view provides authentication that will either result in failure or success,
     // failure simply means that the prompt is getting delayed.
     connect(d, &PamWorker::failed, this, &PamAuthenticator::failed);
 
     m_thread.start();
     init(service, user);
 }
 
 PamAuthenticator::~PamAuthenticator()
 {
     cancel();
     m_thread.quit();
     m_thread.wait();
 }
 
 void PamAuthenticator::init(const QString &service, const QString &user)
 {
     QMetaObject::invokeMethod(d, [this, service, user]() {
         d->start(service, user);
     });
 }
 
 bool PamAuthenticator::isBusy() const
 {
     return m_busy;
 }
 
 void PamAuthenticator::setBusy(bool busy)
 {
     if (m_busy != busy) {
         m_busy = busy;
         Q_EMIT busyChanged();
     }
 }
 
 bool PamAuthenticator::isUnlocked() const
 {
     return m_unlocked;
 }
 
 void PamAuthenticator::tryUnlock()
 {
     m_unlocked = false;
     QMetaObject::invokeMethod(d, &PamWorker::authenticate);
 }
 
 void PamAuthenticator::respond(const QByteArray &response)
 {
     QMetaObject::invokeMethod(
         d,
         [this, response]() {
             Q_EMIT d->promptResponseReceived(response);
         },
         Qt::QueuedConnection);
 }
 
 void PamAuthenticator::cancel()
 {
     m_prompt.clear();
     m_promptForSecret.clear();
     m_infoMessage.clear();
     m_errorMessage.clear();
     QMetaObject::invokeMethod(d, &PamWorker::cancelled);
 }
 
 // Force emit the signals when a view connects to them. This prevents a race condition where screens appear after
 // stateful signals (such as prompt) had been emitted and end up in an incorrect state.
 // (e.g. https://bugs.kde.org/show_bug.cgi?id=456210 where the view ends up in a no-prompt state)
 void PamAuthenticator::connectNotify(const QMetaMethod &signal)
 {
     // TODO remove this function for Plasma 6. The properties should be bound to  so we don't need to force
     // emit them every time a view connects.
 
     // NOTE signals are queued because during connect qml is not yet ready to receive them
 
     if (m_unlocked && signal == QMetaMethod::fromSignal(&PamAuthenticator::succeeded)) {
         signal.invoke(this, Qt::QueuedConnection);
         return;
     }
 
     for (const auto &[signalMethod, memberString] : m_signalsToMembers)
     {
         if (signal != signalMethod) {
             continue;
         }
 
         if (!memberString.isNull()) {
             signalMethod.invoke(this, Qt::QueuedConnection, Q_ARG(QString, memberString));
             return;
         }
     }
 }
 
 QString PamAuthenticator::getPrompt() const
 {
     return m_prompt;
 }
 
 QString PamAuthenticator::getPromptForSecret() const
 {
     return m_promptForSecret;
 }
 
 QString PamAuthenticator::getInfoMessage() const
 {
     return m_infoMessage;
 }
 
 QString PamAuthenticator::getErrorMessage() const
 {
     return m_errorMessage;
 }
 
 #include "pamauthenticator.moc"