--- /dev/null
+/*
+ * Copyright (C) 2010 Canonical Ltd.
+ * Author: Robert Ancell <robert.ancell@canonical.com>
+ *
+ * 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 3 of the License, or (at your option) any later
+ * version. See http://www.gnu.org/copyleft/gpl.html the full text of the
+ * license.
+ */
+
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/wait.h>
+#include <pwd.h>
+#include <unistd.h>
+#include <security/pam_appl.h>
+
+#include "display.h"
+
+enum {
+ EXITED,
+ LAST_SIGNAL
+};
+static guint signals[LAST_SIGNAL] = { 0 };
+
+struct DisplayPrivate
+{
+ /* X process */
+ GPid xserver_pid;
+
+ /* Session process (either greeter or user session) */
+ GPid session_pid;
+
+ /* Authentication thread */
+ GThread *authentication_thread;
+
+ /* Queue to feed responses to the authentication thread */
+ GAsyncQueue *authentication_response_queue;
+
+ /* Current D-Bus call context */
+ DBusGMethodInvocation *dbus_context;
+
+ /* Authentication handle */
+ pam_handle_t *pam_handle;
+
+ /* User logged in as */
+ char *username;
+
+ /* TRUE if user has been authenticated */
+ gboolean authenticated;
+
+ /* TRUE if in user session */
+ gboolean in_user_session;
+
+ // FIXME: Token for secure access to this server
+};
+
+G_DEFINE_TYPE (Display, display, G_TYPE_OBJECT);
+
+static void start_greeter (Display *display);
+static void start_user_session (Display *display);
+
+Display *
+display_new (void)
+{
+ return g_object_new (DISPLAY_TYPE, NULL);
+}
+
+static void
+session_watch_cb (GPid pid, gint status, gpointer data)
+{
+ Display *display = data;
+
+ if (WIFEXITED (status))
+ g_debug ("Display exited with return value %d", WEXITSTATUS (status));
+ else if (WIFSIGNALED (status))
+ g_debug ("Display terminated with signal %d", WTERMSIG (status));
+
+ display->priv->session_pid = 0;
+
+ // FIXME: Check for respawn loops
+ if (display->priv->authenticated && !display->priv->in_user_session)
+ start_user_session (display);
+ else
+ start_greeter (display);
+}
+
+static void
+start_session (Display *display, const char *username, char * const argv[])
+{
+ pid_t pid;
+ struct passwd *user_info;
+
+ g_return_if_fail (display->priv->session_pid == 0);
+
+ errno = 0;
+ user_info = getpwnam (username);
+ if (!user_info)
+ {
+ g_warning ("Unable to get information on user %s: %s", username, strerror (errno));
+ return;
+ }
+
+ pid = fork ();
+ if (pid < 0)
+ {
+ g_warning ("Failed to fork session: %s", strerror (errno));
+ return;
+ }
+ else if (pid > 0)
+ {
+ g_debug ("Child process started with PID %d", pid);
+ display->priv->session_pid = pid;
+ g_child_watch_add (display->priv->session_pid, session_watch_cb, display);
+ return;
+ }
+
+ if (setgid (user_info->pw_gid) != 0)
+ {
+ g_warning ("Failed to set group ID: %s", strerror (errno));
+ _exit(1);
+ }
+ // FIXME: Is there a risk of connecting to the process for a user in the given group and accessing memory?
+ if (setuid (user_info->pw_uid) != 0)
+ {
+ g_warning ("Failed to set user ID: %s", strerror (errno));
+ _exit(1);
+ }
+ if (chdir (user_info->pw_dir) != 0)
+ g_warning ("Failed to change directory: %s", strerror (errno));
+
+ /* Reset environment */
+ // FIXME: Check these work
+ clearenv ();
+ setenv ("USER", user_info->pw_name, 1);
+ setenv ("HOME", user_info->pw_dir, 1);
+ setenv ("SHELL", user_info->pw_shell, 1);
+ setenv ("HOME", user_info->pw_dir, 1);
+ setenv ("DISPLAY", ":0", 1);
+
+ execv (argv[0], argv);
+}
+
+static void
+start_user_session (Display *display)
+{
+ char *argv[] = { "/usr/bin/gnome-terminal", NULL };
+ display->priv->in_user_session = TRUE;
+ start_session (display, display->priv->username, argv);
+}
+
+static void
+start_greeter (Display *display)
+{
+ char *argv[] = { "/usr/bin/lightdm-greeter", NULL };
+ display->priv->in_user_session = FALSE;
+ g_free (display->priv->username);
+ display->priv->username = NULL;
+ start_session (display, "gdm", argv);
+}
+
+static int
+pam_conv_cb (int num_msg, const struct pam_message **msg,
+ struct pam_response **resp, void *app_data)
+{
+ Display *display = app_data;
+ gpointer response;
+
+ /* Respond to d-bus query with messages */
+ dbus_g_method_return (display->priv->dbus_context, 666); // ACTIONS
+ display->priv->dbus_context = NULL;
+
+ /* Wait for responses */
+ response = g_async_queue_pop (display->priv->authentication_response_queue);
+
+ /* Fill responses */
+ // ...
+
+ return 0;
+}
+
+static gpointer
+authenticate_cb (gpointer data)
+{
+ Display *display = data;
+ struct pam_conv conversation = { pam_conv_cb, display };
+ int result;
+
+ pam_start ("check_pass", display->priv->username, &conversation, &display->priv->pam_handle);
+ result = pam_authenticate (display->priv->pam_handle, 0);
+
+ /* Thread complete */
+ g_thread_join (display->priv->authentication_thread);
+ display->priv->authentication_thread = NULL;
+ g_async_queue_unref (display->priv->authentication_response_queue);
+ display->priv->authentication_response_queue = NULL;
+
+ /* Respond to D-Bus request */
+ dbus_g_method_return (display->priv->dbus_context, 888); // FINISHED
+ display->priv->dbus_context = NULL;
+
+ return NULL;
+}
+
+gboolean
+display_start_authentication (Display *display, const char *username, DBusGMethodInvocation *context)
+{
+ GError *error = NULL;
+
+ // FIXME: Only allow calls from the greeter
+
+ g_return_val_if_fail (display->priv->authentication_thread != NULL, FALSE);
+
+ /* Store authentication request and D-Bus request to respond to */
+ g_free (display->priv->username);
+ display->priv->username = g_strdup (username);
+ display->priv->dbus_context = context;
+
+ /* Start thread */
+ display->priv->authentication_response_queue = g_async_queue_new ();
+ display->priv->authentication_thread = g_thread_create (authenticate_cb, display, TRUE, &error);
+ if (!display->priv->authentication_thread)
+ {
+ g_warning ("Failed to start authentication thread: %s", error->message);
+ display->priv->dbus_context = NULL;
+ return FALSE;
+ }
+ g_clear_error (&error);
+
+ return TRUE;
+}
+
+gboolean
+display_continue_authentication (Display *display, int data, DBusGMethodInvocation *context)
+{
+ g_return_val_if_fail (display->priv->authentication_thread == NULL, FALSE);
+ g_return_val_if_fail (display->priv->dbus_context != NULL, FALSE);
+
+ // FIXME: Only allow calls from the greeter
+
+ /* Push onto queue and store request to respond to */
+ display->priv->dbus_context = context;
+ g_async_queue_push (display->priv->authentication_response_queue, GINT_TO_POINTER (data));
+
+ return TRUE;
+}
+
+static void
+xserver_watch_cb (GPid pid, gint status, gpointer data)
+{
+ Display *display = data;
+
+ if (WIFEXITED (status))
+ g_debug ("Display exited with return value %d", WEXITSTATUS (status));
+ else if (WIFSIGNALED (status))
+ g_debug ("Display terminated with signal %d", WTERMSIG (status));
+
+ display->priv->xserver_pid = 0;
+
+ g_signal_emit (display, signals[EXITED], 0);
+}
+
+static void
+display_init (Display *display)
+{
+ GError *error = NULL;
+ char *argv[] = { "/usr/bin/X", ":0", NULL };
+ char *env[] = { NULL };
+ gboolean result;
+
+ display->priv = G_TYPE_INSTANCE_GET_PRIVATE (display, DISPLAY_TYPE, DisplayPrivate);
+
+ result = g_spawn_async (NULL, /* Working directory */
+ argv,
+ env,
+ G_SPAWN_DO_NOT_REAP_CHILD,
+ NULL, NULL,
+ &display->priv->xserver_pid,
+ &error);
+ if (!result)
+ g_warning ("Unable to create display: %s", error->message);
+ else
+ g_child_watch_add (display->priv->xserver_pid, xserver_watch_cb, display);
+ g_clear_error (&error);
+
+ /* TODO: Do autologin if this is requested */
+ start_greeter (display);
+}
+
+static void
+display_class_init (DisplayClass *klass)
+{
+ g_type_class_add_private (klass, sizeof (DisplayPrivate));
+
+ signals[EXITED] =
+ g_signal_new ("exited",
+ G_TYPE_FROM_CLASS (klass),
+ G_SIGNAL_RUN_LAST,
+ G_STRUCT_OFFSET (DisplayClass, exited),
+ NULL, NULL,
+ g_cclosure_marshal_VOID__VOID,
+ G_TYPE_NONE, 0);
+}
projects / sojka / lightdm.git / commitdiff