mutter/patches/gdm-util-Only-start-fingerprint-service-synchronously-whe.patch

From: =?utf-8?b?Ik1hcmNvIFRyZXZpc2FuIChUcmV2acOxbyki?= <mail@3v1n0.net>
Date: Tue, 1 Mar 2022 11:57:20 +0100
Subject: gdm/util: Only start fingerprint service synchronously when it's
 default

On ShellUserVerifier construction we used to start fprintd in a sync
fashion all the times, however in case the daemon had startup failures
or was hanging for whatever reason (like due to devices probing, given
that fprintd synchronously wait for them all to be initialized) we used
to just fail, leaving gdm or the lockscreen inusable.

While this could be prevented with a try/catch statement, there's no
much point to wait for fprintd if that's not the default authentication
service, and so:
 - If we use gdm-fingerprint as default auth method, use a sync call to
   initialize it and in case of failures, just continue with fallback
   authentication mechanism (password)

 - Otherwise, asynchronously initialize fprintd and continue with the
   ShellUserVerifier without fingerprint support until we got a reply.
   In case the service fails to deliver us a result, we don't give up
   but we will try doing that at each authentication via
   _checkForFingerprintReader().
   In case all works properly, as per the previous commit, once the
   initialization is done, we'll start the fingerprint PAM gdm service.

Fixes #5168

Bug-Ubuntu: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1962566
Bug-GNOME: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/5168
Origin: https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2267
---
 js/gdm/util.js | 129 +++++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 102 insertions(+), 27 deletions(-)

diff --git a/js/gdm/util.js b/js/gdm/util.js
index 89ad544..3697ecd 100644
--- a/js/gdm/util.js
+++ b/js/gdm/util.js
@@ -43,6 +43,7 @@ export const DISABLE_USER_LIST_KEY = 'disable-user-list';
 
 // Give user 48ms to read each character of a PAM message
 const USER_READ_TIME = 48;
+const FINGERPRINT_SERVICE_PROXY_TIMEOUT = 5000;
 const FINGERPRINT_ERROR_TIMEOUT_WAIT = 15;
 
 /**
@@ -108,16 +109,50 @@ export class ShellUserVerifier extends Signals.EventEmitter {
         this._preemptingService = null;
 
         this._settings = new Gio.Settings({schema_id: LOGIN_SCREEN_SCHEMA});
-        this._settings.connect('changed',
-            this._updateDefaultService.bind(this));
-        this._updateDefaultService();
 
-        this._fprintManager = new FprintManagerProxy(Gio.DBus.system,
-            'net.reactivated.Fprint',
-            '/net/reactivated/Fprint/Manager',
-            null,
-            null,
-            Gio.DBusProxyFlags.DO_NOT_LOAD_PROPERTIES);
+        this._settings.connect('changed', () => this._updateDefaultServiceWithFallback());
+
+        this._fingerprintReaderType = FingerprintReaderType.NONE;
+        if (this._settings.get_boolean(FINGERPRINT_AUTHENTICATION_KEY)) {
+            const fprintManager = new FprintManagerProxy(Gio.DBus.system,
+                'net.reactivated.Fprint',
+                '/net/reactivated/Fprint/Manager',
+                null,
+                null,
+                Gio.DBusProxyFlags.DO_NOT_LOAD_PROPERTIES |
+                Gio.DBusProxyFlags.DO_NOT_AUTO_START_AT_CONSTRUCTION |
+                Gio.DBusProxyFlags.DO_NOT_CONNECT_SIGNALS);
+
+            // Do not wait too much for fprintd to reply, as in case it hangs
+            // we should fail early without having the shell to misbehave because
+            fprintManager.set_default_timeout(FINGERPRINT_SERVICE_PROXY_TIMEOUT);
+
+            this._updateDefaultService();
+
+            if (!this._defaultService) {
+                // Fingerprint is the default one, we must wait for it!
+                try {
+                    const [devicePath] = fprintManager.GetDefaultDeviceSync();
+                    this._fprintManager = fprintManager;
+
+                    const fprintDeviceProxy = new FprintDeviceProxy(Gio.DBus.system,
+                        'net.reactivated.Fprint', devicePath, null, null,
+                        Gio.DBusProxyFlags.NOT_CONNECT_SIGNALS);
+                    this._setFingerprintReaderType(fprintDeviceProxy['scan-type']);
+                } catch (e) {
+                    logError(e, 'Failed to initialize fprintd service');
+                } finally {
+                    this._updateDefaultServiceWithFallback();
+                }
+            } else {
+                // Ensure fingerprint service starts, but do not wait for it
+                this._updateFingerprintReaderType(fprintManager, null).then(
+                    () => (this._fprintManager = fprintManager)).catch(
+                    e => logError(e, 'Failed to initialize fprintd service'));
+            }
+        } else {
+            this._updateDefaultServiceWithFallback();
+        }
         this._smartcardManager = SmartcardManager.getSmartcardManager();
 
         // We check for smartcards right away, since an inserted smartcard
@@ -136,6 +171,7 @@ export class ShellUserVerifier extends Signals.EventEmitter {
         this.reauthenticating = false;
 
         this._failCounter = 0;
+        this._startedServices = new Set();
         this._unavailableServices = new Set();
 
         this._credentialManagers = {};
@@ -225,6 +261,7 @@ export class ShellUserVerifier extends Signals.EventEmitter {
 
         this._clearUserVerifier();
         this._clearMessageQueue();
+        this._startedServices.clear();
     }
 
     destroy() {
@@ -345,27 +382,52 @@ export class ShellUserVerifier extends Signals.EventEmitter {
     }
 
     async _checkForFingerprintReader() {
-        this._fingerprintReaderType = FingerprintReaderType.NONE;
-
-        if (!this._settings.get_boolean(FINGERPRINT_AUTHENTICATION_KEY) ||
-            this._fprintManager == null) {
-            this._updateDefaultService();
+        if (!this._fprintManager) {
+            this._updateDefaultServiceWithFallback();
             return;
         }
 
+        if (this._fingerprintReaderType !== FingerprintReaderType.NONE)
+            return;
+
+        await this._updateFingerprintReaderType(this._fprintManager, this._cancellable);
+    }
+
+    async _updateFingerprintReaderType(fprintManager, cancellable) {
         try {
-            const [device] = await this._fprintManager.GetDefaultDeviceAsync(
-                Gio.DBusCallFlags.NONE, this._cancellable);
-            const fprintDeviceProxy = new FprintDeviceProxy(Gio.DBus.system,
-                'net.reactivated.Fprint',
-                device);
-            const fprintDeviceType = fprintDeviceProxy['scan-type'];
+            // Wrappers don't support null cancellable, so let's cheat about it
+            const [devicePath] = await fprintManager.GetDefaultDeviceAsync(
+                cancellable ? cancellable : Gio.DBusCallFlags.NONE);
+            const fprintDeviceProxy = await new Promise((resolve, reject) => {
+                const proxy = new FprintDeviceProxy(Gio.DBus.system,
+                    'net.reactivated.Fprint', devicePath, (_, error) => {
+                        if (error)
+                            reject(error);
+                        else
+                            resolve(proxy);
+                    }, cancellable, Gio.DBusProxyFlags.NOT_CONNECT_SIGNALS);
+            });
+            this._setFingerprintReaderType(fprintDeviceProxy['scan-type']);
+            this._updateDefaultServiceWithFallback();
+
+            if (this._userVerifier &&
+                !this._startedServices.has(FINGERPRINT_SERVICE_NAME)) {
+                if (!this._hold?.isAcquired())
+                    this._hold = new Batch.Hold();
+                await this._maybeStartFingerprintVerification();
+            }
+        } catch (e) {
+            if (!e.matches(Gio.IOErrorEnum, Gio.IOErrorEnum.CANCELLED))
+                logError(e);
+        }
+    }
 
-            this._fingerprintReaderType = fprintDeviceType === 'swipe'
-                ? FingerprintReaderType.SWIPE
-                : FingerprintReaderType.PRESS;
-            this._updateDefaultService();
-        } catch (e) {}
+    _setFingerprintReaderType(fprintDeviceType) {
+        this._fingerprintReaderType =
+            FingerprintReaderType[fprintDeviceType.toUpperCase()];
+
+        if (this._fingerprintReaderType === undefined)
+            throw new Error(`Unexpected fingerprint device type '${fprintDeviceType}'`);
     }
 
     _onCredentialManagerAuthenticated(credentialManager, _token) {
@@ -466,6 +528,7 @@ export class ShellUserVerifier extends Signals.EventEmitter {
             'problem', this._onProblem.bind(this),
             'info-query', this._onInfoQuery.bind(this),
             'secret-info-query', this._onSecretInfoQuery.bind(this),
+            'conversation-started', this._onConversationStarted.bind(this),
             'conversation-stopped', this._onConversationStopped.bind(this),
             'service-unavailable', this._onServiceUnavailable.bind(this),
             'reset', this._onReset.bind(this),
@@ -519,6 +582,10 @@ export class ShellUserVerifier extends Signals.EventEmitter {
             this._defaultService = SMARTCARD_SERVICE_NAME;
         else if (this._fingerprintReaderType !== FingerprintReaderType.NONE)
             this._defaultService = FINGERPRINT_SERVICE_NAME;
+    }
+
+    _updateDefaultServiceWithFallback() {
+        this._updateDefaultService();
 
         if (!this._defaultService) {
             log('no authentication service is enabled, using password authentication');
@@ -557,11 +624,14 @@ export class ShellUserVerifier extends Signals.EventEmitter {
 
     _beginVerification() {
         this._startService(this._getForegroundService());
+        this._maybeStartFingerprintVerification();
+    }
 
+    async _maybeStartFingerprintVerification() {
         if (this._userName &&
             this._fingerprintReaderType !== FingerprintReaderType.NONE &&
             !this.serviceIsForeground(FINGERPRINT_SERVICE_NAME))
-            this._startService(FINGERPRINT_SERVICE_NAME);
+            await this._startService(FINGERPRINT_SERVICE_NAME);
     }
 
     _onChoiceListQuery(client, serviceName, promptMessage, list) {
@@ -654,8 +724,9 @@ export class ShellUserVerifier extends Signals.EventEmitter {
     _onReset() {
         // Clear previous attempts to authenticate
         this._failCounter = 0;
+        this._startedServices.clear();
         this._unavailableServices.clear();
-        this._updateDefaultService();
+        this._updateDefaultServiceWithFallback();
 
         this.emit('reset');
     }
@@ -736,6 +807,10 @@ export class ShellUserVerifier extends Signals.EventEmitter {
             this._queueMessage(serviceName, errorMessage, MessageType.ERROR);
     }
 
+    _onConversationStarted(client, serviceName) {
+        this._startedServices.add(serviceName);
+    }
+
     _onConversationStopped(client, serviceName) {
         // If the login failed with the preauthenticated oVirt credentials
         // then discard the credentials and revert to default authentication