auth: Support parallel fingerprint auth

I chose to use Fprint's dbus interface directly rather than going through pam (which uses Fprint's dbus interface) due to poor handling of system sleep somewhere between fprintd and pam. When preparing for sleep, fprintd puts the device to sleep, which causes VerifyStatus to emit with verify-unknown-error, which normally should be responded to by calling both Device.StopVerify and Device.Release (and this is what pam does). Unfortunately, if you try to release the device when the system is preparing for sleep, you'll get an error that the device is busy and then you can't can't claim or release the device for 30 seconds.

pam also has a max timeout for pam_fprintd.so of 99 seconds, and so if we used pam, we'd have to deal with the timeouts and keep restarting the auth conversation.

gdm/gnome-session lock seems to get around these issues by having a shutter on top of the lock screen that you have to interact with first that gives gnome-session a trigger to start fingerprint auth.

CMakeLists.txt

@@ -56,7 +56,8 @@ pkg_check_modules(
   pangocairo
   libdrm
   gbm
-  hyprutils>=0.2.3)
+  hyprutils>=0.2.3
+  sdbus-c++)
 
 file(GLOB_RECURSE SRCFILES CONFIGURE_DEPENDS "src/*.cpp")
 add_executable(hyprlock ${SRCFILES})

src/config/ConfigManager.cpp

@@ -50,6 +50,8 @@ void CConfigManager::init() {
     m_config.addConfigValue("general:immediate_render", Hyprlang::INT{0});
     m_config.addConfigValue("general:pam_module", Hyprlang::STRING{"hyprlock"});
     m_config.addConfigValue("general:fractional_scaling", Hyprlang::INT{2});
+    m_config.addConfigValue("general:enable_fingerprint", Hyprlang::INT{0});
+    m_config.addConfigValue("general:fingerprint_ready_message", Hyprlang::STRING{""});
 
     m_config.addSpecialCategory("background", Hyprlang::SSpecialCategoryOptions{.key = nullptr, .anonymousKeyBased = true});
     m_config.addSpecialConfigValue("background", "monitor", Hyprlang::STRING{""});

src/core/Fingerprint.cpp

@@ -0,0 +1,234 @@
+#include "Fingerprint.hpp"
+#include "../helpers/Log.hpp"
+#include "src/config/ConfigManager.hpp"
+
+#include <filesystem>
+#include <unistd.h>
+#include <pwd.h>
+
+#include <cstring>
+#include <thread>
+
+static const auto FPRINT        = "net.reactivated.Fprint";
+static const auto DEVICE        = "net.reactivated.Fprint.Device";
+static const auto MANAGER       = "net.reactivated.Fprint.Manager";
+static const auto LOGIN_MANAGER = "org.freedesktop.login1.Manager";
+static const auto RETRY_MESSAGE = "Could not match fingerprint. Try again.";
+
+CFingerprint::CFingerprint() {
+    static auto* const PFINGERPRINTREADY = (Hyprlang::STRING*)(g_pConfigManager->getValuePtr("general:fingerprint_ready_message"));
+    m_sFingerprintReady                  = *PFINGERPRINTREADY;
+}
+
+static void fingerprintUnlockCallback(std::shared_ptr<CTimer> self, void* data) {
+    g_pHyprlock->unlock();
+}
+
+void CFingerprint::start() {
+    static auto* const PENABLEFINGERPRINT = (Hyprlang::INT* const*)g_pConfigManager->getValuePtr("general:enable_fingerprint");
+    const bool         ENABLEFINGERPRINT  = **PENABLEFINGERPRINT;
+    if (!ENABLEFINGERPRINT) {
+        return;
+    }
+    std::thread([this]() {
+        // For grace or SIGUSR1 unlocks
+        if (g_pHyprlock->isUnlocked())
+            return;
+
+        setupDBUS();
+
+        if (m_bAuthenticated)
+            g_pHyprlock->addTimer(std::chrono::milliseconds(1), fingerprintUnlockCallback, nullptr);
+    }).detach();
+}
+
+std::optional<std::string> CFingerprint::getLastMessage() {
+    return m_sDBUSState.message.empty() ? std::nullopt : std::optional(m_sDBUSState.message);
+}
+
+void CFingerprint::terminate() {
+    if (m_sDBUSState.connection)
+        m_sDBUSState.connection->leaveEventLoop();
+}
+
+bool CFingerprint::setupDBUS() {
+    m_sDBUSState.connection = sdbus::createSystemBusConnection();
+
+    registerSleepHandler();
+
+    if (m_sDBUSState.sleeping) {
+        m_sDBUSState.connection->enterEventLoop();
+    } else if (startVerify()) {
+        m_sDBUSState.message = m_sFingerprintReady;
+        g_pHyprlock->enqueueForceUpdateTimers();
+        m_sDBUSState.connection->enterEventLoop();
+    }
+
+    if (m_sDBUSState.abort)
+        return true;
+
+    releaseDevice();
+    return true;
+}
+
+void CFingerprint::registerSleepHandler() {
+    m_sDBUSState.login = sdbus::createProxy(*m_sDBUSState.connection.get(), "org.freedesktop.login1", "/org/freedesktop/login1");
+
+    m_sDBUSState.sleeping = m_sDBUSState.login->getProperty("PreparingForSleep").onInterface(LOGIN_MANAGER);
+    m_sDBUSState.login->uponSignal("PrepareForSleep").onInterface(LOGIN_MANAGER).call([this](bool start) {
+        Debug::log(LOG, "prepare for sleep");
+        if (start) {
+            m_sDBUSState.sleeping = true;
+            stopVerify();
+            m_sDBUSState.inhibitLock.reset();
+        } else {
+            m_sDBUSState.sleeping = false;
+            inhibitSleep();
+            std::this_thread::sleep_for(std::chrono::seconds(1));
+            if (startVerify()) {
+                m_sDBUSState.message = m_sFingerprintReady;
+                g_pHyprlock->enqueueForceUpdateTimers();
+            }
+        }
+    });
+    m_sDBUSState.login->finishRegistration();
+    if (!m_sDBUSState.sleeping)
+        inhibitSleep();
+}
+
+void CFingerprint::inhibitSleep() {
+    m_sDBUSState.login->callMethod("Inhibit")
+        .onInterface(LOGIN_MANAGER)
+        .withArguments("sleep", "hyprlock", "Release fingerprint before sleep", "delay")
+        .storeResultsTo(m_sDBUSState.inhibitLock);
+}
+
+bool CFingerprint::createDeviceProxy() {
+    auto              proxy = sdbus::createProxy(*m_sDBUSState.connection.get(), FPRINT, "/net/reactivated/Fprint/Manager");
+
+    sdbus::ObjectPath path;
+    try {
+        proxy->callMethod("GetDefaultDevice").onInterface(MANAGER).storeResultsTo(path);
+    } catch (sdbus::Error& e) {
+        Debug::log(WARN, "Couldn't connect to Fprint service ({})", e.what());
+        return false;
+    }
+    Debug::log(LOG, "Using dbus path {}", path.c_str());
+    m_sDBUSState.device = sdbus::createProxy(*m_sDBUSState.connection.get(), FPRINT, path);
+
+    m_sDBUSState.device->uponSignal("VerifyFingerSelected").onInterface(DEVICE).call([](const std::string& finger) { Debug::log(LOG, "Finger: {}", finger); });
+    m_sDBUSState.device->uponSignal("VerifyStatus").onInterface(DEVICE).call([this](const std::string& result, const bool done) { handleVerifyStatus(result, done); });
+
+    m_sDBUSState.device->finishRegistration();
+    return true;
+}
+
+void CFingerprint::handleVerifyStatus(const std::string& result, bool done) {
+    Debug::log(LOG, "Status: {} {}", done, result);
+    auto matchResult = s_mapStringToTestType[result];
+    if (m_sDBUSState.sleeping && matchResult != MatchResult::Disconnected) {
+        return;
+    }
+    std::unique_lock<std::mutex> lk(m_sDBUSState.messageMutex);
+    switch (matchResult) {
+        case MatchResult::NoMatch: //The verification did not match, Device.VerifyStop should now be called.
+            stopVerify();
+            if (m_sDBUSState.retries < 2) {
+                startVerify();
+                done = false;
+                m_sDBUSState.retries++;
+                m_sDBUSState.message = RETRY_MESSAGE;
+                if (clearRetryTextTimer)
+                    clearRetryTextTimer->cancel();
+                clearRetryTextTimer = g_pHyprlock->addTimer(
+                    std::chrono::seconds(2),
+                    [this](std::shared_ptr<CTimer>, void* data) {
+                        std::unique_lock<std::mutex> lk(m_sDBUSState.messageMutex);
+                        if (m_sDBUSState.message == RETRY_MESSAGE) {
+                            m_sDBUSState.message = m_sFingerprintReady;
+                            g_pHyprlock->enqueueForceUpdateTimers();
+                        }
+                    },
+                    nullptr);
+            } else {
+                m_sDBUSState.message = "Fingerprint auth disabled: too many failed attempts.";
+            }
+            break;
+        case MatchResult::UnknownError:
+            stopVerify();
+            m_sDBUSState.message = "Unknown fingerprint error.";
+            break;
+        case MatchResult::Match:
+            stopVerify();
+            m_bAuthenticated      = true;
+            m_sDBUSState.message = "";
+            Debug::log(LOG, "matched");
+            break;
+        case MatchResult::Retry: m_sDBUSState.message = "Please retry fingerprint scan."; break;
+        case MatchResult::SwipeTooShort: m_sDBUSState.message = "Swipe too short - try again."; break;
+        case MatchResult::FingerNotCentered: m_sDBUSState.message = "Finger not centered - try again."; break;
+        case MatchResult::RemoveAndRetry: m_sDBUSState.message = "Remove your finger and try again."; break;
+        case MatchResult::Disconnected: m_sDBUSState.abort = true; break;
+    }
+    g_pHyprlock->enqueueForceUpdateTimers();
+    if (done || m_sDBUSState.abort) {
+        Debug::log(LOG, "leaving dbus loop");
+        m_sDBUSState.connection->leaveEventLoop();
+    }
+}
+
+bool CFingerprint::claimDevice() {
+    try {
+        const auto currentUser = ""; // Empty string means use the caller's id.
+        m_sDBUSState.device->callMethod("Claim").onInterface(DEVICE).withArguments(currentUser);
+    } catch (sdbus::Error& e) {
+        Debug::log(WARN, "could not claim device, {}", e.what());
+        return false;
+    }
+    Debug::log(LOG, "Claimed device");
+    return true;
+}
+
+bool CFingerprint::startVerify() {
+    if (!m_sDBUSState.device) {
+        if (!createDeviceProxy())
+            return false;
+
+        claimDevice();
+    }
+    try {
+        auto finger = "any"; // Any finger.
+        m_sDBUSState.device->callMethod("VerifyStart").onInterface(DEVICE).withArguments(finger);
+    } catch (sdbus::Error& e) {
+        Debug::log(WARN, "Could not start verifying, {}", e.what());
+        return false;
+    }
+    Debug::log(LOG, "started verifying");
+    return true;
+}
+
+bool CFingerprint::stopVerify() {
+    if (!m_sDBUSState.device)
+        return false;
+    try {
+        m_sDBUSState.device->callMethod("VerifyStop").onInterface(DEVICE);
+    } catch (sdbus::Error& e) {
+        Debug::log(WARN, "could not stop verifying, {}", e.what());
+        return false;
+    }
+    Debug::log(LOG, "Stopped verification");
+    return true;
+}
+
+bool CFingerprint::releaseDevice() {
+    if (!m_sDBUSState.device)
+        return false;
+    try {
+        m_sDBUSState.device->callMethod("Release").onInterface(DEVICE);
+    } catch (sdbus::Error& e) {
+        Debug::log(WARN, "could not release device, {}", e.what());
+        return false;
+    }
+    Debug::log(LOG, "Released device");
+    return true;
+}

src/core/Fingerprint.hpp

@@ -0,0 +1,73 @@
+#pragma once
+
+#include "hyprlock.hpp"
+
+#include <memory>
+#include <optional>
+#include <string>
+#include <mutex>
+#include <condition_variable>
+#include <sdbus-c++/sdbus-c++.h>
+
+class CFingerprint {
+  public:
+    CFingerprint();
+
+    void                       start();
+
+    std::optional<std::string> getLastMessage();
+
+    void                       terminate();
+    bool                       setupDBUS();
+
+  private:
+    enum class MatchResult {
+        NoMatch,
+        Match,
+        Retry,
+        SwipeTooShort,
+        FingerNotCentered,
+        RemoveAndRetry,
+        Disconnected,
+        UnknownError,
+    };
+    struct SDBUSState {
+        std::string                         message = "";
+
+        std::mutex                          messageMutex;
+
+        std::unique_ptr<sdbus::IConnection> connection;
+        std::unique_ptr<sdbus::IProxy>      login;
+        std::unique_ptr<sdbus::IProxy>      device;
+        sdbus::UnixFd                       inhibitLock;
+
+        bool                                abort    = false;
+        int                                 retries  = 0;
+        bool                                sleeping = false;
+    } m_sDBUSState;
+
+    std::string                        m_sFingerprintReady;
+    bool                               m_bAuthenticated    = false;
+    std::shared_ptr<CTimer>            clearRetryTextTimer;
+
+    std::map<std::string, MatchResult> s_mapStringToTestType = {{"verify-no-match", MatchResult::NoMatch},
+                                                                {"verify-match", MatchResult::Match},
+                                                                {"verify-retry-scan", MatchResult::Retry},
+                                                                {"verify-swipe-too-short", MatchResult::SwipeTooShort},
+                                                                {"verify-finger-not-centered", MatchResult::FingerNotCentered},
+                                                                {"verify-remove-and-retry", MatchResult::RemoveAndRetry},
+                                                                {"verify-disconnected", MatchResult::Disconnected},
+                                                                {"verify-unknown-error", MatchResult::UnknownError}};
+    void                               handleVerifyStatus(const std::string& result, const bool done);
+
+    void                               registerSleepHandler();
+    void                               inhibitSleep();
+
+    bool                               createDeviceProxy();
+    bool                               claimDevice();
+    bool                               startVerify();
+    bool                               stopVerify();
+    bool                               releaseDevice();
+};
+
+inline std::unique_ptr<CFingerprint> g_pFingerprint;

src/core/hyprlock.cpp

@@ -4,6 +4,7 @@
 #include "../renderer/Renderer.hpp"
 #include "Auth.hpp"
 #include "Egl.hpp"
+#include "Fingerprint.hpp"
 #include "linux-dmabuf-unstable-v1-protocol.h"
 #include <sys/wait.h>
 #include <sys/poll.h>
@@ -417,6 +418,9 @@ void CHyprlock::run() {
     g_pAuth = std::make_unique<CAuth>();
     g_pAuth->start();
 
+    g_pFingerprint = std::make_unique<CFingerprint>();
+    g_pFingerprint->start();
+
     registerSignalAction(SIGUSR1, handleUnlockSignal, SA_RESTART);
     registerSignalAction(SIGUSR2, handleForceUpdateSignal);
     registerSignalAction(SIGRTMIN, handlePollTerminate);
@@ -572,6 +576,7 @@ void CHyprlock::run() {
     pthread_kill(pollThr.native_handle(), SIGRTMIN);
 
     g_pAuth->terminate();
+    g_pFingerprint->terminate();
 
     // wait for threads to exit cleanly to avoid a coredump
     pollThr.join();

src/renderer/widgets/IWidget.cpp

@@ -2,6 +2,7 @@
 #include "../../helpers/Log.hpp"
 #include "../../core/hyprlock.hpp"
 #include "../../core/Auth.hpp"
+#include "../../core/Fingerprint.hpp"
 #include <chrono>
 #include <unistd.h>
 #include <pwd.h>
@@ -166,6 +167,12 @@ IWidget::SFormatResult IWidget::formatString(std::string in) {
         result.allowForceUpdate = true;
     }
 
+    if (in.contains("$FPRINTMESSAGE")) {
+        const auto FPRINTMESSAGE = g_pFingerprint->getLastMessage();
+        replaceInString(in, "$FPRINTMESSAGE", FPRINTMESSAGE.has_value() ? FPRINTMESSAGE.value() : "");
+        result.allowForceUpdate = true;
+    }
+
     if (in.starts_with("cmd[") && in.contains("]")) {
         // this is a command
         CVarList vars(in.substr(4, in.find_first_of(']') - 4), 0, ',', true);