0003-Flatpak-Support-KeePassXC-Browser-integration.patch

From 6070fc75c6f7a17dfc53831cbc638f4c56b3e8a4 Mon Sep 17 00:00:00 2001
From: AsavarTzeth <asavartzeth@gmail.com>
Date: Wed, 2 Sep 2020 17:07:12 +0200
Subject: [PATCH 3/4] Flatpak: Support KeePassXC-Browser integration

Flatpak browser integration and near feature parity with non-sandboxed
distribution types. This is primarily made possible by:

1. The unix socket instead listens at $XDG_RUNTIME_DIR/app/$FLATPAK_ID/
   which is host accessible by default. Using the Flatpak permission:
   --filesystem=xdg-run isn't possible (nor allowed).

2. Including a wrapper script which acts as a workaround to the Flatpak
   limitation of a single exportable host command per app. Running
   org.keepassxc.KeePassXC on the host will run this instead of
   keepassxc directly.

There are also some Flatpak specific UX improvements, such as better
sandbox compatibility and automatic proxy path detection. Custom
locations are disabled because it requires extensive Flatpak knowledge
and even then there's isn't any one reliable and easy workaround.

What does work

 - Browser integration, including all supported browsers.
 - Automatic proxy path detection and updating of manifests.
 - This works with different Flatpak installations: system, user and
   custom ones, as long as the path uses safe POSIX portable file names.

Limitations and caveats

- The browser cannot be sandboxed or it will be unable execute commands
  in the host namespace, which is currently required to use native
  messaging; i.e. web browsers cannot be installed as Flatpaks.

Note: The Native Messaging Host API would be a lot more sandbox friendly
with the addition of D-Bus support, as an alternative to stdio.
---
 src/browser/BrowserSettingsWidget.cpp  | 12 ++++++++
 src/browser/BrowserShared.cpp          |  3 ++
 src/browser/NativeMessageInstaller.cpp | 34 +++++++++++++++++++++-
 src/browser/NativeMessageInstaller.h   |  2 ++
 utils/flatpak-command-wrapper.sh       | 40 ++++++++++++++++++++++++++
 5 files changed, 90 insertions(+), 1 deletion(-)
 create mode 100755 utils/flatpak-command-wrapper.sh

diff --git a/src/browser/BrowserSettingsWidget.cpp b/src/browser/BrowserSettingsWidget.cpp
index d0bdad1f..9d6eed06 100644
--- a/src/browser/BrowserSettingsWidget.cpp
+++ b/src/browser/BrowserSettingsWidget.cpp
@@ -171,6 +171,18 @@ void BrowserSettingsWidget::loadSettings()
     m_ui->browserGlobalWarningWidget->setCloseButtonVisible(false);
     m_ui->browserGlobalWarningWidget->setAutoHideTimeout(-1);
 #endif
+#ifdef KEEPASSXC_DIST_FLATPAK
+    // Guarantees proxy path works with different flatpak installations
+    m_ui->updateBinaryPath->setChecked(true);
+    m_ui->updateBinaryPath->setEnabled(false);
+    // The sandbox makes custom proxy locations very unintuitive
+    m_ui->useCustomProxy->setChecked(false);
+    m_ui->useCustomProxy->setEnabled(false);
+    m_ui->useCustomProxy->setVisible(false);
+    m_ui->customProxyLocation->setVisible(false);
+    // Won't work with xdg portals and executables that must be browser accessible
+    m_ui->customProxyLocationBrowseButton->setVisible(false);
+#endif
 
     const auto customBrowserSet = settings->customBrowserSupport();
     m_ui->customBrowserSupport->setChecked(customBrowserSet);
diff --git a/src/browser/BrowserShared.cpp b/src/browser/BrowserShared.cpp
index 69d0db49..52101b1a 100644
--- a/src/browser/BrowserShared.cpp
+++ b/src/browser/BrowserShared.cpp
@@ -30,6 +30,9 @@ namespace BrowserShared
         const auto serverName = QStringLiteral("/org.keepassxc.KeePassXC.BrowserServer");
 #if defined(KEEPASSXC_DIST_SNAP)
         return QProcessEnvironment::systemEnvironment().value("SNAP_USER_COMMON") + serverName;
+#elif defined(KEEPASSXC_DIST_FLATPAK)
+        return QStandardPaths::writableLocation(QStandardPaths::RuntimeLocation)
+            + "/app/" + "org.keepassxc.KeePassXC" + serverName;
 #elif defined(Q_OS_UNIX) && !defined(Q_OS_MACOS)
         // Use XDG_RUNTIME_DIR instead of /tmp if it's available
         QString path = QStandardPaths::writableLocation(QStandardPaths::RuntimeLocation);
diff --git a/src/browser/NativeMessageInstaller.cpp b/src/browser/NativeMessageInstaller.cpp
index 8b038f61..16c4b9b0 100644
--- a/src/browser/NativeMessageInstaller.cpp
+++ b/src/browser/NativeMessageInstaller.cpp
@@ -30,6 +30,7 @@
 #include <QProcessEnvironment>
 #include <QSettings>
 #include <QStandardPaths>
+#include <QRegularExpression>
 
 using namespace BrowserShared;
 
@@ -247,8 +248,10 @@ QString NativeMessageInstaller::getProxyPath() const
     }
 
     QString path;
-#ifdef KEEPASSXC_DIST_APPIMAGE
+#if defined(KEEPASSXC_DIST_APPIMAGE)
     path = QProcessEnvironment::systemEnvironment().value("APPIMAGE");
+#elif defined(KEEPASSXC_DIST_FLATPAK)
+    path = NativeMessageInstaller::constructFlatpakPath();
 #else
     path = QCoreApplication::applicationDirPath() + QStringLiteral("/keepassxc-proxy");
 #ifdef Q_OS_WIN
@@ -259,6 +262,35 @@ QString NativeMessageInstaller::getProxyPath() const
     return QDir::toNativeSeparators(path);
 }
 
+/** Constructs a host accessible proxy path for use with flatpak
+ *
+ * @return path Path to host accessible wrapper script (org.keepassxc.KeePassXC)
+ */
+
+#ifdef KEEPASSXC_DIST_FLATPAK
+QString NativeMessageInstaller::constructFlatpakPath() const
+{
+    // Find and extract the host flatpak data directory (in /var)
+    QString path;
+    QSettings settings("/.flatpak-info",QSettings::IniFormat);
+    settings.beginGroup("Instance");
+    QString appPath = settings.value("app-path").toString();
+
+    QRegularExpression re("^((?:/[\\.\\w-]*)+)+/app");
+    QRegularExpressionMatch match = re.match(appPath);
+    if (match.hasMatch()) {
+        // Construct a proxy path that should work with all flatpak installations
+        path = match.captured(1) + "/exports/bin/" + "org.keepassxc.KeePassXC";
+    } else {
+        // Fallback to the most common and default flatpak installation path
+        path = "/var/lib/flatpak/exports/bin/org.keepassxc.KeePassXC";
+    }
+    settings.endGroup();
+
+    return path;
+}
+#endif
+
 /**
  * Constructs the JSON script file used with native messaging
  *
diff --git a/src/browser/NativeMessageInstaller.h b/src/browser/NativeMessageInstaller.h
index 4c0e339e..f605287a 100644
--- a/src/browser/NativeMessageInstaller.h
+++ b/src/browser/NativeMessageInstaller.h
@@ -40,6 +40,8 @@ private:
     QJsonObject constructFile(BrowserShared::SupportedBrowsers browser);
     bool createNativeMessageFile(BrowserShared::SupportedBrowsers browser);
 
+    QString constructFlatpakPath() const;
+
     Q_DISABLE_COPY(NativeMessageInstaller);
 };
 
diff --git a/utils/flatpak-command-wrapper.sh b/utils/flatpak-command-wrapper.sh
new file mode 100755
index 00000000..5b6ff8e2
--- /dev/null
+++ b/utils/flatpak-command-wrapper.sh
@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+#
+# Flatpak Multiple Commands Wrapper
+# Copyright (C) 2017 KeePassXC team <https://keepassxc.org/>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 2 or (at your option)
+# version 3 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This script is a workaround to the limitation of one command per Flatpak
+# manifest. It solves this by redirecting stdio to keepassxc-proxy, as
+# necessary, based upon matching command line arguments.
+
+# For format of parsed arguments, see "Connection-based messaging" at:
+# https://developer.mozilla.org/docs/Mozilla/Add-ons/WebExtensions/Native_messaging
+
+readonly appId='org.keepassxc.KeePassXC'
+# Chromium, Google Chrome, Vivaldi & Brave
+readonly arg1='chrome-extension://oboonakemofpalcgghocfoadofidjkkk'
+# Firefox & Tor Browser
+readonly arg2='keepassxc-browser@keepassxc.org'
+
+# Browser integration is enabled if unix socket exists
+if [[ -S "${XDG_RUNTIME_DIR}/app/${appId}/${appId}.BrowserServer" ]]; then
+  if [[ "$1" =~ "${arg1}" ]] || [[ "$2" =~ "${arg2}" ]]; then
+    exec keepassxc-proxy "$@"
+  fi
+fi
+
+# If no arguments are matched or browser integration is off execute keepassxc
+exec keepassxc "$@"
-- 
2.30.0