fix: fingerprint lid open (#3448)

* lock: keep the fingerprint reader usable across suspend

The reader stopped responding after the lid was closed and opened, after a long
idle period, and after suspend.

The shell held a PAM session for as long as the screen was locked, so a suspend
always landed on a running verify. fprintd then suspends the device under the
verify, pam_fprintd's ReleaseDevice fails with "device is still busy", and the
claim is never released, so every later Claim fails until fprintd restarts. The
reader is now released when the monitors blank and armed again when they come
back, so a suspend has nothing left to wedge.

The PAM profile drops to max-tries=1 and sets an explicit timeout. pam_fprintd
only counts a wrong finger, so one finished session is now one wrong scan and
maxFprintTries means the number of scans it names rather than five times that.
A timeout expiry arrives as PamResult.Error, exactly like a device fault, so a
session that ran at least as long as the configured timeout is treated as a
planned renewal instead of spending the error budget and painting an error.

A suspend that still lands while the screen is on wedges as before. Recovery now
waits out fprintd's idle timeout instead of climbing to it, which brings the
reader back about 37 seconds after resume instead of about 98.

SessionService gains lidOpened from UPower, because logind can ignore the lid on
AC and resume alone is not enough. The lock PAM state machine is fixed alongside:
PamResult.Failed was dropped, a pending retry outlived the contexts that owned
it, and an availability check reset the wrong-scan counter.

* lock: time the fingerprint session from the verify, not the claim

pam_fprintd's timeout runs from the verify, but the session age was measured
from start(), which folds the claim into it. A slow claim plus a verify that
failed before its own timeout could add up past the timeout and be taken for a
planned renewal, skipping the backoff. A session that never reached a verify had
the same problem.

The age now starts at the message pam_fprintd sends when the verify begins, so a
session that never verified can never qualify as an expiry, and a slow claim no
longer ages a fault. The message is translated and quickshell clears it before
completed, so only its timing is used, never its text.

That message arrives after pam_fprintd has already armed its deadline, because
VerifyStart is asynchronous, so the age read here runs short of the real timeout
and a slack makes it up. The bias is deliberate. A fault misread as a timeout
costs one extra retry, while a timeout misread as a fault parks the reader behind
a backoff that grows to a minute, which on an idle lock screen would leave it
unusable most of the time.

Also corrects the comment that claimed a timeout is reported without a message.

---------

(cherry picked from commit d7074a53eb)

core/internal/qmlchecks/lockscreen_input_test.go

@@ -3,6 +3,7 @@ package qmlchecks
 import (
 	"os"
 	"regexp"
+	"strconv"
 	"strings"
 	"testing"
 )
@@ -55,3 +56,51 @@ func TestLockScreenPamSupportsManagedAndSystemPolicies(t *testing.T) {
 		t.Fatalf("DMS-managed policy must generate the sanitized user PAM stack on Nix-store installs")
 	}
 }
+
+func TestLockScreenFprintProfileMatchesPamQml(t *testing.T) {
+	profile, err := os.ReadFile("../../../quickshell/assets/pam/fprint")
+	if err != nil {
+		t.Fatalf("read fprint PAM profile: %v", err)
+	}
+
+	qml, err := os.ReadFile("../../../quickshell/Modules/Lock/Pam.qml")
+	if err != nil {
+		t.Fatalf("read lock screen PAM QML: %v", err)
+	}
+
+	// Pam.qml tells a pam_fprintd timeout expiry apart from a device fault by
+	// how long the session ran, so a profile change that is not mirrored in
+	// sessionTimeoutMs makes real faults look like planned renewals.
+	profileTimeout := regexp.MustCompile(`pam_fprintd\.so[^\n]*\btimeout=(\d+)`).FindSubmatch(profile)
+	if profileTimeout == nil {
+		t.Fatalf("fprint profile must set an explicit pam_fprintd timeout")
+	}
+	qmlTimeout := regexp.MustCompile(`sessionTimeoutMs:\s*(\d+)`).FindSubmatch(qml)
+	if qmlTimeout == nil {
+		t.Fatalf("Pam.qml must declare sessionTimeoutMs")
+	}
+
+	seconds, err := strconv.Atoi(string(profileTimeout[1]))
+	if err != nil {
+		t.Fatalf("parse profile timeout: %v", err)
+	}
+	millis, err := strconv.Atoi(string(qmlTimeout[1]))
+	if err != nil {
+		t.Fatalf("parse sessionTimeoutMs: %v", err)
+	}
+	if seconds*1000 != millis {
+		t.Fatalf("sessionTimeoutMs is %dms but the fprint profile sets timeout=%d", millis, seconds)
+	}
+
+	// fprintd 1.94.0 and older ignore this option when it is longer than two
+	// digits and silently fall back to 30 seconds.
+	if len(profileTimeout[1]) > 2 {
+		t.Fatalf("pam_fprintd timeout=%s is too long for fprintd <= 1.94.0, which would ignore it", profileTimeout[1])
+	}
+
+	// One finished session must equal one wrong finger, otherwise
+	// SettingsData.maxFprintTries silently means a multiple of the scans it names.
+	if !regexp.MustCompile(`pam_fprintd\.so[^\n]*\bmax-tries=1\b`).Match(profile) {
+		t.Fatalf("fprint profile must use max-tries=1 so the shell counts wrong scans one for one")
+	}
+}

quickshell/Modules/Lock/LockScreenContent.qml

@@ -82,6 +82,8 @@ Item {
             return I18n.tr("Too many attempts - locked out");
         if (root.pamState === "fail")
             return I18n.tr("Incorrect password - try again");
+        if (pam.fprint.status === "disabled")
+            return "";
         if (pam.fprintState === "error")
             return I18n.tr("Fingerprint error");
         if (pam.fprintState === "max")
@@ -861,10 +863,15 @@ Item {
                             name: {
                                 if (pam.u2fPending)
                                     return "passkey";
-                                if (pam.fprint.tries >= SettingsData.maxFprintTries)
+                                switch (pam.fprint.status) {
+                                case "max":
+                                case "stopped":
                                     return "fingerprint_off";
-                                if (pam.fprint.active || pam.fprint.retrying)
+                                case "active":
                                     return "fingerprint";
+                                case "retrying":
+                                    return "hourglass_empty";
+                                }
                                 if (pam.u2f.active)
                                     return "passkey";
                                 return "lock";
@@ -1005,6 +1012,8 @@ Item {
                                 return;
                             }
 
+                            root.pam.retryFprintOnActivity();
+
                             if (root.unlocking) {
                                 event.accepted = true;
                                 return;

quickshell/Modules/Lock/LockSurface.qml

@@ -16,7 +16,20 @@ FocusScope {
     signal passwordChanged(string newPassword)
     signal unlockRequested
 
+    HoverHandler {
+        enabled: root.pam.awaitingActivityRetry
+        onPointChanged: root.pam.retryFprintOnActivity()
+    }
+
+    PointHandler {
+        onActiveChanged: {
+            if (active)
+                root.pam.retryFprintOnActivity();
+        }
+    }
+
     Keys.onPressed: event => {
+        root.pam.retryFprintOnActivity();
         if (videoScreensaver.active && videoScreensaver.inputEnabled) {
             videoScreensaver.dismiss();
             event.accepted = true;

quickshell/Modules/Lock/Pam.qml

@@ -32,9 +32,8 @@ Scope {
 
     function resetAuthFlows(): void {
         passwd.abort();
-        fprint.abort();
+        fprint.stop();
         u2f.abort();
-        errorRetry.running = false;
         u2fErrorRetry.running = false;
         u2fPendingTimeout.running = false;
         passwdActiveTimeout.running = false;
@@ -58,9 +57,8 @@ Scope {
         if (!root.unlockInProgress) {
             root.unlockInProgress = true;
             passwd.abort();
-            fprint.abort();
+            fprint.stop();
             u2f.abort();
-            errorRetry.running = false;
             u2fErrorRetry.running = false;
             u2fPendingTimeout.running = false;
             root.u2fPending = false;
@@ -217,7 +215,7 @@ Scope {
 
             if (res === PamResult.Success) {
                 if (!root.unlockInProgress) {
-                    fprint.abort();
+                    fprint.stop();
                     root.proceedAfterPrimaryAuth();
                 }
                 return;
@@ -260,69 +258,147 @@ Scope {
     PamContext {
         id: fprint
 
-        property bool available: SettingsData.lockFingerprintReady
-        property int tries
-        property int errorTries
-        property bool retrying: false
+        readonly property bool available: SettingsData.lockFingerprintReady
+        property int tries: 0
+        property int errorTries: 0
+        property double attemptStartedAt: 0
+        property bool completedDuringStart: false
+        readonly property int maxErrorTries: 200
+        readonly property int daemonIdleExitMs: 30000
+        // sessionTimeoutMs mirrors `timeout=` in assets/pam/fprint
+        readonly property int sessionTimeoutMs: 90000
+        readonly property int verifyStartSlackMs: 10000
+        readonly property bool retrying: errorRetry.running
+        readonly property int retryInterval: errorRetry.interval
+        readonly property bool allowed: available && SettingsData.enableFprint && root.lockSecured && !root.fprintSuppressedByPrimaryPam && !root.unlockInProgress && !root.u2fPending && !SessionService.preparingForSleep && !IdleService.monitorsOff && tries < SettingsData.maxFprintTries
+        readonly property string status: {
+            if (!available || !SettingsData.enableFprint || !root.lockSecured || root.fprintSuppressedByPrimaryPam)
+                return "disabled";
+            if (tries >= SettingsData.maxFprintTries)
+                return "max";
+            if (!allowed)
+                return "paused";
+            if (active)
+                return "active";
+            if (retrying)
+                return "retrying";
+            return errorTries >= maxErrorTries ? "stopped" : "idle";
+        }
+
+        function stop(): void {
+            errorRetry.stop();
+            attemptStartedAt = 0;
+            abort();
+        }
+
+        // pam_fprintd reports an expired timeout as PAM_AUTHINFO_UNAVAIL, the same
+        // result a device fault gives, and its "Verification timed out" message is
+        // translated, so age is the signal we can rely on. Its timeout runs from the
+        // verify rather than from the claim, which is why the age is measured from
+        // the message announcing the verify: a slow claim then cannot make a fault
+        // look old enough, and a session that never reached a verify never qualifies.
+        // That message lands after pam_fprintd has already armed its deadline, so the
+        // age read here runs short of the real timeout and the slack makes it up. The
+        // bias is deliberate: a timeout misread as a fault parks the reader behind the
+        // backoff, while a fault misread as a timeout costs one extra retry.
+        function attemptSettled(): bool {
+            return attemptStartedAt > 0 && Date.now() - attemptStartedAt >= sessionTimeoutMs - verifyStartSlackMs;
+        }
 
         function checkAvail(): void {
-            if (!available || !SettingsData.enableFprint || !root.lockSecured || root.fprintSuppressedByPrimaryPam) {
-                retrying = false;
-                abort();
+            if (!allowed) {
+                stop();
+                return;
+            }
+            if (!active && !retrying)
+                startAttempt();
+        }
+
+        function startAttempt(): void {
+            if (!allowed || errorTries >= maxErrorTries) {
+                stop();
                 return;
             }
             if (active)
                 return;
+            errorRetry.stop();
+            if (root.fprintState === "error")
+                root.fprintState = "";
+            attemptStartedAt = 0;
+            completedDuringStart = false;
+            if (start())
+                return;
+            if (!completedDuringStart)
+                scheduleErrorRetry();
+        }
 
-            tries = 0;
+        function scheduleErrorRetry(): void {
+            stop();
+            if (!allowed)
+                return;
+            errorTries++;
+            root.fprintState = "error";
+            if (errorTries === 1)
+                root.flashMsg();
+            fprintStateReset.restart();
+            if (errorTries < maxErrorTries)
+                errorRetry.restart();
+        }
+
+        function recover(): void {
+            if (!allowed)
+                return;
             errorTries = 0;
-            retrying = false;
-            start();
+            if (!active)
+                startAttempt();
+        }
+
+        onAllowedChanged: {
+            if (!allowed)
+                stop();
+            else
+                Qt.callLater(checkAvail);
         }
 
         config: "fprint"
         configDirectory: Quickshell.shellDir + "/assets/pam"
 
+        onPamMessage: {
+            if (attemptStartedAt === 0)
+                attemptStartedAt = Date.now();
+        }
+
         onCompleted: res => {
-            if (!available)
+            completedDuringStart = true;
+            if (!allowed)
                 return;
 
             switch (res) {
             case PamResult.Success:
-                retrying = false;
-                if (!root.unlockInProgress) {
-                    passwd.abort();
-                    root.proceedAfterPrimaryAuth();
-                }
+                stop();
+                passwd.abort();
+                root.proceedAfterPrimaryAuth();
                 return;
             case PamResult.Error:
-                errorTries++;
-                if (errorTries < 200) {
-                    retrying = true;
-                    abort();
-                    errorRetry.restart();
+                if (attemptSettled()) {
+                    stop();
+                    errorTries = 0;
+                    startAttempt();
                     return;
                 }
-                retrying = false;
-                abort();
+                scheduleErrorRetry();
                 return;
+            case PamResult.Failed:
             case PamResult.MaxTries:
-                retrying = false;
+                stop();
                 tries++;
-                if (tries < SettingsData.maxFprintTries) {
-                    root.fprintState = "fail";
-                    start();
-                } else {
-                    root.fprintState = "max";
-                    abort();
-                }
-                break;
-            default:
+                errorTries = 0;
+                root.fprintState = tries < SettingsData.maxFprintTries ? "fail" : "max";
+                root.flashMsg();
+                fprintStateReset.restart();
+                startAttempt();
                 return;
             }
-
-            root.flashMsg();
-            fprintStateReset.start();
         }
     }
 
@@ -426,20 +502,35 @@ Scope {
     Timer {
         id: errorRetry
 
-        interval: Math.min(1500 * Math.pow(2, Math.max(0, fprint.errorTries - 1)), 30000)
-        onTriggered: fprint.start()
+        // A device wedged by a suspend mid-verify only comes back when fprintd
+        // restarts, and fprintd only exits after its idle timeout with no client
+        // attached, so the second retry outlasts that instead of climbing to it.
+        interval: {
+            if (fprint.errorTries <= 1)
+                return 1500;
+            if (fprint.errorTries === 2)
+                return fprint.daemonIdleExitMs + 5000;
+            return 60000;
+        }
+        onTriggered: fprint.startAttempt()
+    }
+
+    readonly property bool awaitingActivityRetry: fprint.errorTries > 0 && !fprint.retrying && !fprint.active
+
+    function retryFprintOnActivity(): void {
+        if (root.awaitingActivityRetry)
+            fprint.recover();
     }
 
     Connections {
         target: SessionService
 
-        // timers run on monotonic time, so suspend leaves the backoff remainder to burn after wake (#3171)
         function onSessionResumed() {
-            if (!fprint.available || !SettingsData.enableFprint || !root.lockSecured || root.fprintSuppressedByPrimaryPam)
-                return;
-            fprint.errorTries = 0;
-            if (errorRetry.running)
-                errorRetry.restart();
+            fprint.recover();
+        }
+
+        function onLidOpened() {
+            fprint.recover();
         }
     }
 
@@ -491,7 +582,10 @@ Scope {
         id: fprintStateReset
 
         interval: 4000
-        onTriggered: root.fprintState = ""
+        onTriggered: {
+            if (root.fprintState !== "max")
+                root.fprintState = "";
+        }
     }
 
     onLockSecuredChanged: {
@@ -508,6 +602,8 @@ Scope {
         root.attemptInfoMessages = [];
         root.lockoutAnnouncedThisAttempt = false;
         root.resetAuthFlows();
+        fprint.tries = 0;
+        fprint.errorTries = 0;
         if (!SettingsData.lockPamExternallyManaged && !dankshellConfigWatcher.loaded && !userPamWatcher.loaded)
             ensureUserPamConfig();
         // FileView cannot watch a path that does not exist yet; re-read so a
@@ -521,11 +617,17 @@ Scope {
         target: SettingsData
 
         function onEnableFprintChanged(): void {
-            fprint.checkAvail();
+            if (SettingsData.enableFprint)
+                fprint.recover();
+            else
+                fprint.checkAvail();
         }
 
         function onLockFingerprintReadyChanged(): void {
-            fprint.checkAvail();
+            if (SettingsData.lockFingerprintReady)
+                fprint.recover();
+            else
+                fprint.checkAvail();
         }
 
         function onEnableU2fChanged(): void {

quickshell/Services/SessionService.qml

@@ -42,11 +42,14 @@ Singleton {
     signal sessionLocked
     signal sessionUnlocked
     signal sessionResumed
+    signal lidOpened
     signal loginctlStateChanged
 
     property bool stateInitialized: false
     property string prepareForSleepSubscriptionId: ""
     property bool prepareForSleepSubscriptionPending: false
+    property string lidSubscriptionId: ""
+    property bool lidSubscriptionPending: false
     property double lastResumeSignalTimestamp: 0
 
     readonly property string socketPath: Quickshell.env("DMS_SOCKET")
@@ -696,7 +699,7 @@ Singleton {
             if (DMSService.isConnected) {
                 checkDMSCapabilities();
             } else {
-                clearPrepareForSleepSubscriptionState();
+                clearPowerSubscriptionState();
             }
         }
 
@@ -714,10 +717,11 @@ Singleton {
         }
 
         function onDbusSignalReceived(subscriptionId, data) {
-            if (subscriptionId !== prepareForSleepSubscriptionId) {
-                return;
+            if (subscriptionId === prepareForSleepSubscriptionId) {
+                handlePrepareForSleepSignal(data);
+            } else if (subscriptionId === lidSubscriptionId) {
+                handleLidPropertiesChanged(data);
             }
-            handlePrepareForSleepSignal(data);
         }
     }
 
@@ -779,14 +783,41 @@ Singleton {
 
         if (DMSService.capabilities.includes("dbus")) {
             ensurePrepareForSleepSubscription();
+            ensureLidSubscription();
         } else {
-            clearPrepareForSleepSubscriptionState();
+            clearPowerSubscriptionState();
         }
     }
 
-    function clearPrepareForSleepSubscriptionState() {
+    function clearPowerSubscriptionState() {
         prepareForSleepSubscriptionId = "";
         prepareForSleepSubscriptionPending = false;
+        lidSubscriptionId = "";
+        lidSubscriptionPending = false;
+    }
+
+    function ensureLidSubscription() {
+        if (!DMSService.isConnected || !DMSService.capabilities.includes("dbus"))
+            return;
+        if (lidSubscriptionId || lidSubscriptionPending)
+            return;
+
+        lidSubscriptionPending = true;
+        DMSService.dbusSubscribe("system", "org.freedesktop.UPower", "/org/freedesktop/UPower", "org.freedesktop.DBus.Properties", "PropertiesChanged", response => {
+            lidSubscriptionPending = false;
+            if (response.error) {
+                log.warn("Failed to subscribe to lid changes:", response.error);
+                return;
+            }
+            lidSubscriptionId = response.result?.subscriptionId || "";
+        });
+    }
+
+    function handleLidPropertiesChanged(data) {
+        if (data?.path !== "/org/freedesktop/UPower" || data.body?.[0] !== "org.freedesktop.UPower")
+            return;
+        if (data.body?.[1]?.LidIsClosed === false)
+            lidOpened();
     }
 
     function ensurePrepareForSleepSubscription() {

quickshell/assets/pam/fprint

@@ -1,6 +1,9 @@
 #%PAM-1.0
 
-auth    required    pam_fprintd.so  max-tries=5
+# timeout bounds how long a stuck fprintd session can hold the reader.
+# Modules/Lock/Pam.qml mirrors the value in sessionTimeoutMs to tell an expiry
+# apart from a device fault; change both together.
+auth    required    pam_fprintd.so  max-tries=1 timeout=90
 account required    pam_permit.so
 password required   pam_deny.so
 session required    pam_permit.so