system-helper: Add PolicyKit authentication for system helper

configure.ac

@@ -101,6 +101,8 @@ AC_SUBST([GLIB_MKENUMS], [`$PKG_CONFIG --variable glib_mkenums glib-2.0`])
 AC_SUBST([GLIB_COMPILE_RESOURCES], [`$PKG_CONFIG --variable glib_compile_resources gio-2.0`])
 AC_SUBST([GDBUS_CODEGEN], [`$PKG_CONFIG --variable gdbus_codegen gio-2.0`])
 
+POLKIT_GOBJECT_REQUIRED=0.98
+
 PKG_CHECK_MODULES(BASE, [glib-2.0 gio-2.0 gio-unix-2.0])
 AC_SUBST(BASE_CFLAGS)
 AC_SUBST(BASE_LIBS)
@@ -108,6 +110,9 @@ PKG_CHECK_MODULES(SOUP, [libsoup-2.4])
 AC_SUBST(SOUP_CFLAGS)
 AC_SUBST(SOUP_LIBS)
 
+PKG_CHECK_MODULES(POLKIT, \
+		  polkit-gobject-1 >= $POLKIT_GOBJECT_REQUIRED)
+
 AC_ARG_ENABLE([xauth],
               AC_HELP_STRING([--disable-xauth],
                              [Disable Xauth use]),

system-helper/Makefile.am.inc

@@ -28,7 +28,21 @@ xdg_app_system_helper_SOURCES = \
 	system-helper/xdg-app-system-helper.c	\
 	system-helper/xdg-app-resources.h	\
 	system-helper/xdg-app-resources.c	\
+	lib/xdg-app-error.c	\
 	$(NULL)
 
-xdg_app_system_helper_LDADD = $(BASE_LIBS) $(OSTREE_LIBS) libxdgapp-common.la
-xdg_app_system_helper_CFLAGS = $(BASE_CFLAGS) $(OSTREE_CFLAGS)
+xdg_app_system_helper_LDADD = $(BASE_LIBS) $(OSTREE_LIBS) $(POLKIT_LIBS) libxdgapp-common.la
+xdg_app_system_helper_CFLAGS = $(BASE_CFLAGS) $(OSTREE_CFLAGS) $(POLKIT_CFLAGS)
+
+polkit_rulesdir = $(datadir)/polkit-1/rules.d
+dist_polkit_rules_DATA =					\
+	system-helper/org.freedesktop.XdgApp.rules
+
+polkit_policydir = $(datadir)/polkit-1/actions
+dist_polkit_policy_DATA =					\
+	system-helper/org.freedesktop.XdgApp.policy
+
+@INTLTOOL_POLICY_RULE@
+
+EXTRA_DIST += system-helper/org.freedesktop.XdgApp.policy.in
+DISTCLEANFILES += system-helper/org.freedesktop.XdgApp.policy

system-helper/org.freedesktop.XdgApp.policy.in

@@ -0,0 +1,86 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE policyconfig PUBLIC
+ "-//freedesktop//DTD PolicyKit Policy Configuration 1.0//EN"
+ "http://www.freedesktop.org/standards/PolicyKit/1.0/policyconfig.dtd">
+<policyconfig>
+
+  <!--
+    Policy definitions for XdgApp system actions.
+    Copyright (c) 2016 Alexander Larsson <alexl@redhat.com>
+  -->
+
+  <vendor>The XdgApp Project</vendor>
+  <vendor_url>https://cgit.freedesktop.org/xdg-app/xdg-app/</vendor_url>
+  <icon_name>package-x-generic</icon_name>
+
+  <action id="org.freedesktop.XdgApp.app-install">
+    <!-- SECURITY:
+          - Normal users do not need authentication to install signed applications
+            from signed repositories, as this cannot exploit a system.
+          - Paranoid users (or parents!) can change this to 'auth_admin' or
+            'auth_admin_keep'.
+     -->
+    <_description>Install signed application</_description>
+    <_message>Authentication is required to install software</_message>
+    <icon_name>package-x-generic</icon_name>
+    <defaults>
+      <allow_any>auth_admin</allow_any>
+      <allow_inactive>auth_admin</allow_inactive>
+      <allow_active>auth_admin_keep</allow_active>
+    </defaults>
+  </action>
+
+  <action id="org.freedesktop.XdgApp.runtime-install">
+    <!-- SECURITY:
+          - Normal users do not need authentication to install signed applications
+            from signed repositories, as this cannot exploit a system.
+          - Paranoid users (or parents!) can change this to 'auth_admin' or
+            'auth_admin_keep'.
+     -->
+    <_description>Install signed runtime</_description>
+    <_message>Authentication is required to install software</_message>
+    <icon_name>package-x-generic</icon_name>
+    <defaults>
+      <allow_any>auth_admin</allow_any>
+      <allow_inactive>auth_admin</allow_inactive>
+      <allow_active>auth_admin_keep</allow_active>
+    </defaults>
+  </action>
+
+  <action id="org.freedesktop.XdgApp.app-update">
+    <!-- SECURITY:
+          - Normal users do not require admin authentication to update an
+            app as the commit will be signed, and the action is required
+            to update the system when unattended.
+          - Changing this to anything other than 'yes' will break unattended
+            updates.
+     -->
+    <_description>Update signed application</_description>
+    <_message>Authentication is required to update software</_message>
+    <icon_name>package-x-generic</icon_name>
+    <defaults>
+      <allow_any>auth_admin</allow_any>
+      <allow_inactive>auth_admin</allow_inactive>
+      <allow_active>yes</allow_active>
+    </defaults>
+  </action>
+
+  <action id="org.freedesktop.XdgApp.runtime-update">
+    <!-- SECURITY:
+          - Normal users do not require admin authentication to update a
+            runtime as the commit will be signed, and the action is required
+            to update the system when unattended.
+          - Changing this to anything other than 'yes' will break unattended
+            updates.
+     -->
+    <_description>Update signed runtime</_description>
+    <_message>Authentication is required to update software</_message>
+    <icon_name>package-x-generic</icon_name>
+    <defaults>
+      <allow_any>auth_admin</allow_any>
+      <allow_inactive>auth_admin</allow_inactive>
+      <allow_active>yes</allow_active>
+    </defaults>
+  </action>
+
+</policyconfig>

system-helper/org.freedesktop.XdgApp.rules

@@ -0,0 +1,8 @@
+polkit.addRule(function(action, subject) {
+    if ((action.id == "org.freedesktop.XdgApp.app-install" ||
+         action.id == "org.freedesktop.XdgApp.runtime-install") &&
+        subject.active == true && subject.local == true &&
+        subject.isInGroup("wheel")) {
+            return polkit.Result.YES;
+    }
+});

system-helper/xdg-app-system-helper.c

@@ -24,12 +24,21 @@
 #include <stdlib.h>
 #include <string.h>
 #include <gio/gio.h>
+#include <polkit/polkit.h>
 
 #include "xdg-app-dbus.h"
 #include "xdg-app-dir.h"
+#include "lib/xdg-app-error.h"
 
+static PolkitAuthority *authority = NULL;
 static GDBusNodeInfo *introspection_data = NULL;
 
+#ifndef glib_autoptr_cleanup_PolkitAuthorizationResult
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(PolkitAuthorizationResult, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(PolkitDetails, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(PolkitSubject, g_object_unref)
+#endif
+
 static gboolean
 handle_deploy (XdgAppSystemHelper *object,
                GDBusMethodInvocation *invocation,
@@ -43,13 +52,14 @@ handle_deploy (XdgAppSystemHelper *object,
   g_autoptr(GFile) path = g_file_new_for_path (arg_repo_path);
   g_autoptr(GError) error = NULL;
   g_autoptr(GFile) deploy_dir = NULL;
+  g_autoptr(PolkitSubject) subject = NULL;
+  g_autoptr(PolkitDetails) details = NULL;
   gboolean is_update;
-
-  is_update = (arg_flags & XDG_APP_HELPER_DEPLOY_FLAGS_UPDATE) != 0;
+  g_autoptr(GMainContext) main_context = NULL;
 
   if ((arg_flags & ~XDG_APP_HELPER_DEPLOY_FLAGS_ALL) != 0)
     {
-      g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR, G_DBUS_ERROR_FAILED,
+      g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR, G_DBUS_ERROR_INVALID_ARGS,
                                              "Unsupported flags enabled: 0x%x", (arg_flags & ~XDG_APP_HELPER_DEPLOY_FLAGS_ALL));
     }
 
@@ -59,6 +69,8 @@ handle_deploy (XdgAppSystemHelper *object,
       return TRUE;
     }
 
+  is_update = (arg_flags & XDG_APP_HELPER_DEPLOY_FLAGS_UPDATE) != 0;
+
   deploy_dir = xdg_app_dir_get_if_deployed (system, arg_ref,
                                             NULL, NULL);
 
@@ -68,7 +80,7 @@ handle_deploy (XdgAppSystemHelper *object,
       if (!is_update)
         {
           /* Can't install already installed app */
-          g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR, G_DBUS_ERROR_FAILED,
+          g_dbus_method_invocation_return_error (invocation, XDG_APP_ERROR, XDG_APP_ERROR_ALREADY_INSTALLED,
                                                  "%s is already installed", arg_ref);
           return TRUE;
         }
@@ -76,7 +88,7 @@ handle_deploy (XdgAppSystemHelper *object,
       real_origin = xdg_app_dir_get_origin (system, arg_ref, NULL, NULL);
       if (real_origin == NULL || strcmp (real_origin, arg_origin) != 0)
         {
-          g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR, G_DBUS_ERROR_FAILED,
+          g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR, G_DBUS_ERROR_INVALID_ARGS,
                                                  "Wrong origin %s for update", arg_origin);
           return TRUE;
         }
@@ -84,7 +96,7 @@ handle_deploy (XdgAppSystemHelper *object,
   else if (!deploy_dir && is_update)
     {
       /* Can't update not installed app */
-      g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR, G_DBUS_ERROR_FAILED,
+      g_dbus_method_invocation_return_error (invocation, XDG_APP_ERROR, XDG_APP_ERROR_ALREADY_INSTALLED,
                                              "%s is not installed", arg_ref);
       return TRUE;
     }
@@ -96,6 +108,10 @@ handle_deploy (XdgAppSystemHelper *object,
       return TRUE;
     }
 
+  /* Work around ostree-pull spinning the default main context for the sync calls */
+  main_context = g_main_context_new ();
+  g_main_context_push_thread_default (main_context);
+
   if (!xdg_app_dir_pull_untrusted_local (system, arg_repo_path,
                                          arg_origin,
                                          arg_ref,
@@ -103,11 +119,14 @@ handle_deploy (XdgAppSystemHelper *object,
                                          NULL,
                                          NULL, &error))
     {
+      g_main_context_pop_thread_default (main_context);
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR, G_DBUS_ERROR_FAILED,
                                              "Error pulling from repo: %s", error->message);
       return TRUE;
     }
 
+  g_main_context_pop_thread_default (main_context);
+
   if (is_update)
     {
       /* TODO: This doesn't support a custom subpath */
@@ -137,6 +156,90 @@ handle_deploy (XdgAppSystemHelper *object,
   return TRUE;
 }
 
+
+static gboolean
+xdg_app_authorize_method_handler (GDBusInterfaceSkeleton *interface,
+                                  GDBusMethodInvocation  *invocation,
+                                  gpointer                user_data)
+{
+  const gchar *method_name;
+  GVariant *parameters;
+  gboolean authorized;
+  const gchar *sender;
+  const gchar *action;
+  g_autoptr(PolkitSubject) subject = NULL;
+  g_autoptr(PolkitDetails) details = NULL;
+  g_autoptr(GError) error = NULL;
+  g_autoptr(PolkitAuthorizationResult) result = NULL;
+
+  authorized = FALSE;
+
+  method_name = g_dbus_method_invocation_get_method_name (invocation);
+  parameters = g_dbus_method_invocation_get_parameters (invocation);
+
+  sender = g_dbus_method_invocation_get_sender (invocation);
+  subject = polkit_system_bus_name_new (sender);
+
+  if (g_strcmp0 (method_name, "Deploy") == 0)
+    {
+      const char *ref, *origin;
+      guint32 flags;
+      gboolean is_update;
+      gboolean is_app;
+
+      g_variant_get_child (parameters, 1, "u", &flags);
+      g_variant_get_child (parameters, 2, "&s", &ref);
+      g_variant_get_child (parameters, 3, "&s", &origin);
+
+      is_update = (flags & XDG_APP_HELPER_DEPLOY_FLAGS_UPDATE) != 0;
+      is_app = g_str_has_prefix (ref, "app/");
+
+      if (is_update)
+        {
+          if (is_app)
+            action = "org.freedesktop.XdgApp.app-update";
+          else
+            action = "org.freedesktop.XdgApp.runtime-update";
+        }
+      else
+        {
+          if (is_app)
+            action = "org.freedesktop.XdgApp.app-install";
+          else
+            action = "org.freedesktop.XdgApp.runtime-install";
+        }
+
+      details = polkit_details_new ();
+      polkit_details_insert (details, "origin", origin);
+      polkit_details_insert (details, "ref", ref);
+
+      result = polkit_authority_check_authorization_sync (authority, subject,
+                                                          action, details,
+                                                          POLKIT_CHECK_AUTHORIZATION_FLAGS_ALLOW_USER_INTERACTION,
+                                                          NULL, &error);
+      if (result == NULL)
+        {
+          g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR, G_DBUS_ERROR_FAILED,
+                                                 "Authorization error: %s", error->message);
+          return FALSE;
+        }
+
+      if (polkit_authorization_result_get_is_authorized (result))
+        authorized = TRUE;
+    }
+
+  if (!authorized)
+    {
+      g_dbus_method_invocation_return_error (invocation,
+                                             G_IO_ERROR,
+                                             G_IO_ERROR_PERMISSION_DENIED,
+                                             "Operation not permitted");
+    }
+
+  return authorized;
+}
+
+
 static void
 on_bus_acquired (GDBusConnection *connection,
                  const gchar     *name,
@@ -147,8 +250,15 @@ on_bus_acquired (GDBusConnection *connection,
 
   helper = xdg_app_system_helper_skeleton_new ();
 
+  g_dbus_interface_skeleton_set_flags (G_DBUS_INTERFACE_SKELETON (helper),
+                                       G_DBUS_INTERFACE_SKELETON_FLAGS_HANDLE_METHOD_INVOCATIONS_IN_THREAD);
+
   g_signal_connect (helper, "handle-deploy", G_CALLBACK (handle_deploy), NULL);
 
+  g_signal_connect (helper, "g-authorize-method",
+                    G_CALLBACK (xdg_app_authorize_method_handler),
+                    NULL);
+
   if (!g_dbus_interface_skeleton_export (G_DBUS_INTERFACE_SKELETON (helper),
                                          connection,
                                          "/org/freedesktop/XdgApp/SystemHelper",
@@ -181,6 +291,7 @@ main (int    argc,
   guint owner_id;
   GMainLoop *loop;
   GBytes *introspection_bytes;
+  g_autoptr(GError) error = NULL;
 
   setlocale (LC_ALL, "");
 
@@ -188,6 +299,13 @@ main (int    argc,
 
   g_set_prgname (argv[0]);
 
+  authority = polkit_authority_get_sync (NULL, &error);
+  if (authority == NULL)
+    {
+      g_printerr ("Can't get polkit authority: %s\n", error->message);
+      return 1;
+    }
+
   introspection_bytes = g_resources_lookup_data ("/org/freedesktop/XdgApp/org.freedesktop.XdgApp.xml", 0, NULL);
   g_assert (introspection_bytes != NULL);