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-rw-r--r--daemon/gdm-display-access-file.c606
1 files changed, 606 insertions, 0 deletions
diff --git a/daemon/gdm-display-access-file.c b/daemon/gdm-display-access-file.c
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--- /dev/null
+++ b/daemon/gdm-display-access-file.c
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+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 8 -*-
+ *
+ * gdm-display-access-file.c - Abstraction around xauth cookies
+ *
+ * Copyright (C) 2007 Ray Strode <rstrode@redhat.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 2, or (at your option)
+ * any later version.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#include "config.h"
+
+#include <errno.h>
+#include <limits.h>
+#include <pwd.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include <glib.h>
+#include <glib-object.h>
+#include <glib/gstdio.h>
+#include <glib/gi18n.h>
+
+#include <X11/Xauth.h>
+
+#include "gdm-display-access-file.h"
+#include "gdm-common.h"
+
+struct _GdmDisplayAccessFile
+{
+ GObject parent;
+
+ char *username;
+ FILE *fp;
+ char *path;
+};
+
+#ifndef GDM_DISPLAY_ACCESS_COOKIE_SIZE
+#define GDM_DISPLAY_ACCESS_COOKIE_SIZE 16
+#endif
+
+#ifndef O_BINARY
+#define O_BINARY 0
+#endif
+
+static void gdm_display_access_file_finalize (GObject * object);
+
+enum
+{
+ PROP_0 = 0,
+ PROP_USERNAME,
+ PROP_PATH
+};
+
+G_DEFINE_TYPE (GdmDisplayAccessFile, gdm_display_access_file, G_TYPE_OBJECT)
+
+static void
+gdm_display_access_file_get_property (GObject *object,
+ guint prop_id,
+ GValue *value,
+ GParamSpec *pspec)
+{
+ GdmDisplayAccessFile *access_file;
+
+ access_file = GDM_DISPLAY_ACCESS_FILE (object);
+
+ switch (prop_id) {
+ case PROP_USERNAME:
+ g_value_set_string (value, access_file->username);
+ break;
+
+ case PROP_PATH:
+ g_value_set_string (value, access_file->path);
+ break;
+
+ default:
+ G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+ }
+}
+
+static void
+gdm_display_access_file_set_property (GObject *object,
+ guint prop_id,
+ const GValue *value,
+ GParamSpec *pspec)
+{
+ GdmDisplayAccessFile *access_file;
+
+ access_file = GDM_DISPLAY_ACCESS_FILE (object);
+
+ switch (prop_id) {
+ case PROP_USERNAME:
+ g_assert (access_file->username == NULL);
+ access_file->username = g_value_dup_string (value);
+ break;
+
+ default:
+ G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+ }
+}
+
+static void
+gdm_display_access_file_class_init (GdmDisplayAccessFileClass *access_file_class)
+{
+ GObjectClass *object_class;
+ GParamSpec *param_spec;
+
+ object_class = G_OBJECT_CLASS (access_file_class);
+
+ object_class->finalize = gdm_display_access_file_finalize;
+ object_class->get_property = gdm_display_access_file_get_property;
+ object_class->set_property = gdm_display_access_file_set_property;
+
+ param_spec = g_param_spec_string ("username",
+ "Username",
+ "Owner of Xauthority file",
+ NULL,
+ G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY);
+ g_object_class_install_property (object_class, PROP_USERNAME, param_spec);
+ param_spec = g_param_spec_string ("path",
+ "Path",
+ "Path to Xauthority file",
+ NULL,
+ G_PARAM_READABLE);
+ g_object_class_install_property (object_class, PROP_PATH, param_spec);
+}
+
+static void
+gdm_display_access_file_init (GdmDisplayAccessFile *access_file)
+{
+}
+
+static void
+gdm_display_access_file_finalize (GObject *object)
+{
+ GdmDisplayAccessFile *file;
+ GObjectClass *parent_class;
+
+ file = GDM_DISPLAY_ACCESS_FILE (object);
+ parent_class = G_OBJECT_CLASS (gdm_display_access_file_parent_class);
+
+ if (file->fp != NULL) {
+ gdm_display_access_file_close (file);
+ }
+ g_assert (file->path == NULL);
+
+ if (file->username != NULL) {
+ g_free (file->username);
+ file->username = NULL;
+ g_object_notify (object, "username");
+ }
+
+ if (parent_class->finalize != NULL) {
+ parent_class->finalize (object);
+ }
+}
+
+GQuark
+gdm_display_access_file_error_quark (void)
+{
+ static GQuark error_quark = 0;
+
+ if (error_quark == 0) {
+ error_quark = g_quark_from_static_string ("gdm-display-access-file");
+ }
+
+ return error_quark;
+}
+
+GdmDisplayAccessFile *
+gdm_display_access_file_new (const char *username)
+{
+ GdmDisplayAccessFile *access_file;
+ g_return_val_if_fail (username != NULL, NULL);
+
+ access_file = g_object_new (GDM_TYPE_DISPLAY_ACCESS_FILE,
+ "username", username,
+ NULL);
+
+ return access_file;
+}
+
+static gboolean
+_get_uid_and_gid_for_user (const char *username,
+ uid_t *uid,
+ gid_t *gid)
+{
+ struct passwd *passwd_entry;
+
+ g_assert (username != NULL);
+ g_assert (uid != NULL);
+ g_assert (gid != NULL);
+
+ errno = 0;
+ gdm_get_pwent_for_name (username, &passwd_entry);
+
+ if (passwd_entry == NULL) {
+ return FALSE;
+ }
+
+ *uid = passwd_entry->pw_uid;
+ *gid = passwd_entry->pw_gid;
+
+ return TRUE;
+}
+
+static void
+clean_up_stale_auth_subdirs (void)
+{
+ GDir *dir;
+ const char *filename;
+
+ dir = g_dir_open (GDM_XAUTH_DIR, 0, NULL);
+
+ if (dir == NULL) {
+ return;
+ }
+
+ while ((filename = g_dir_read_name (dir)) != NULL) {
+ char *path;
+
+ path = g_build_filename (GDM_XAUTH_DIR, filename, NULL);
+
+ /* Will only succeed if the directory is empty
+ */
+ g_rmdir (path);
+ g_free (path);
+ }
+ g_dir_close (dir);
+}
+
+static FILE *
+_create_xauth_file_for_user (const char *username,
+ char **filename,
+ GError **error)
+{
+ char *template;
+ const char *dir_name;
+ char *auth_filename;
+ int fd;
+ FILE *fp;
+ uid_t uid;
+ gid_t gid;
+
+ g_assert (filename != NULL);
+
+ *filename = NULL;
+
+ template = NULL;
+ auth_filename = NULL;
+ fp = NULL;
+ fd = -1;
+
+ /* Create directory if not exist, then set permission 0711 and ownership root:gdm */
+ if (g_file_test (GDM_XAUTH_DIR, G_FILE_TEST_IS_DIR) == FALSE) {
+ g_remove (GDM_XAUTH_DIR);
+ if (g_mkdir (GDM_XAUTH_DIR, 0711) != 0) {
+ g_set_error (error,
+ G_FILE_ERROR,
+ g_file_error_from_errno (errno),
+ "%s", g_strerror (errno));
+ goto out;
+ }
+
+ g_chmod (GDM_XAUTH_DIR, 0711);
+ _get_uid_and_gid_for_user (GDM_USERNAME, &uid, &gid);
+ if (chown (GDM_XAUTH_DIR, 0, gid) != 0) {
+ g_warning ("Unable to change owner of '%s'",
+ GDM_XAUTH_DIR);
+ }
+ } else {
+ /* if it does exist make sure it has correct mode 0711 */
+ g_chmod (GDM_XAUTH_DIR, 0711);
+
+ /* and clean up any stale auth subdirs */
+ clean_up_stale_auth_subdirs ();
+ }
+
+ if (!_get_uid_and_gid_for_user (username, &uid, &gid)) {
+ g_set_error (error,
+ GDM_DISPLAY_ERROR,
+ GDM_DISPLAY_ERROR_GETTING_USER_INFO,
+ _("could not find user “%s” on system"),
+ username);
+ goto out;
+
+ }
+
+ template = g_strdup_printf (GDM_XAUTH_DIR
+ "/auth-for-%s-XXXXXX",
+ username);
+
+ g_debug ("GdmDisplayAccessFile: creating xauth directory %s", template);
+ /* Initially create with mode 01700 then later chmod after we create database */
+ errno = 0;
+ dir_name = g_mkdtemp (template);
+ if (dir_name == NULL) {
+ g_set_error (error,
+ G_FILE_ERROR,
+ g_file_error_from_errno (errno),
+ "Unable to create temp dir from tempalte '%s': %s",
+ template,
+ g_strerror (errno));
+ goto out;
+ }
+
+ g_debug ("GdmDisplayAccessFile: chowning %s to %u:%u",
+ dir_name, (guint)uid, (guint)gid);
+ errno = 0;
+ if (chown (dir_name, uid, gid) < 0) {
+ g_set_error (error,
+ G_FILE_ERROR,
+ g_file_error_from_errno (errno),
+ "Unable to change permission of '%s': %s",
+ dir_name,
+ g_strerror (errno));
+ goto out;
+ }
+
+ auth_filename = g_build_filename (dir_name, "database", NULL);
+
+ g_debug ("GdmDisplayAccessFile: creating %s", auth_filename);
+ /* mode 00600 */
+ errno = 0;
+ fd = g_open (auth_filename,
+ O_RDWR | O_CREAT | O_EXCL | O_BINARY,
+ S_IRUSR | S_IWUSR);
+
+ if (fd < 0) {
+ g_set_error (error,
+ G_FILE_ERROR,
+ g_file_error_from_errno (errno),
+ "Unable to open '%s': %s",
+ auth_filename,
+ g_strerror (errno));
+ goto out;
+ }
+
+ g_debug ("GdmDisplayAccessFile: chowning %s to %u:%u", auth_filename, (guint)uid, (guint)gid);
+ errno = 0;
+ if (fchown (fd, uid, gid) < 0) {
+ g_set_error (error,
+ G_FILE_ERROR,
+ g_file_error_from_errno (errno),
+ "Unable to change owner for '%s': %s",
+ auth_filename,
+ g_strerror (errno));
+ close (fd);
+ fd = -1;
+ goto out;
+ }
+
+ /* now open up permissions on per-session directory */
+ g_debug ("GdmDisplayAccessFile: chmoding %s to 0711", dir_name);
+ g_chmod (dir_name, 0711);
+
+ errno = 0;
+ fp = fdopen (fd, "w");
+ if (fp == NULL) {
+ g_set_error (error,
+ G_FILE_ERROR,
+ g_file_error_from_errno (errno),
+ "%s", g_strerror (errno));
+ close (fd);
+ fd = -1;
+ goto out;
+ }
+
+ *filename = auth_filename;
+ auth_filename = NULL;
+
+ /* don't close it */
+ fd = -1;
+out:
+ g_free (template);
+ g_free (auth_filename);
+ if (fd != -1) {
+ close (fd);
+ }
+
+ return fp;
+}
+
+gboolean
+gdm_display_access_file_open (GdmDisplayAccessFile *file,
+ GError **error)
+{
+ GError *create_error;
+
+ g_return_val_if_fail (file != NULL, FALSE);
+ g_return_val_if_fail (file->fp == NULL, FALSE);
+ g_return_val_if_fail (file->path == NULL, FALSE);
+
+ create_error = NULL;
+ file->fp = _create_xauth_file_for_user (file->username,
+ &file->path,
+ &create_error);
+
+ if (file->fp == NULL) {
+ g_propagate_error (error, create_error);
+ return FALSE;
+ }
+
+ return TRUE;
+}
+
+static void
+_get_auth_info_for_display (GdmDisplayAccessFile *file,
+ GdmDisplay *display,
+ unsigned short *family,
+ unsigned short *address_length,
+ char **address,
+ unsigned short *number_length,
+ char **number,
+ unsigned short *name_length,
+ char **name)
+{
+ int display_number;
+ gboolean is_local;
+
+ gdm_display_is_local (display, &is_local, NULL);
+
+ if (is_local) {
+ /* We could just use FamilyWild here except xauth
+ * (and by extension su and ssh) doesn't support it yet
+ *
+ * https://bugs.freedesktop.org/show_bug.cgi?id=43425
+ */
+ char localhost[HOST_NAME_MAX + 1] = "";
+ *family = FamilyLocal;
+ if (gethostname (localhost, HOST_NAME_MAX) == 0) {
+ *address = g_strdup (localhost);
+ } else {
+ *address = g_strdup ("localhost");
+ }
+ } else {
+ *family = FamilyWild;
+ gdm_display_get_remote_hostname (display, address, NULL);
+ }
+ *address_length = strlen (*address);
+
+ gdm_display_get_x11_display_number (display, &display_number, NULL);
+ *number = g_strdup_printf ("%d", display_number);
+ *number_length = strlen (*number);
+
+ *name = g_strdup ("MIT-MAGIC-COOKIE-1");
+ *name_length = strlen (*name);
+}
+
+gboolean
+gdm_display_access_file_add_display (GdmDisplayAccessFile *file,
+ GdmDisplay *display,
+ char **cookie,
+ gsize *cookie_size,
+ GError **error)
+{
+ GError *add_error;
+ gboolean display_added;
+
+ g_return_val_if_fail (file != NULL, FALSE);
+ g_return_val_if_fail (file->path != NULL, FALSE);
+ g_return_val_if_fail (cookie != NULL, FALSE);
+
+ add_error = NULL;
+ *cookie = gdm_generate_random_bytes (GDM_DISPLAY_ACCESS_COOKIE_SIZE,
+ &add_error);
+
+ if (*cookie == NULL) {
+ g_propagate_error (error, add_error);
+ return FALSE;
+ }
+
+ *cookie_size = GDM_DISPLAY_ACCESS_COOKIE_SIZE;
+
+ display_added = gdm_display_access_file_add_display_with_cookie (file, display,
+ *cookie,
+ *cookie_size,
+ &add_error);
+ if (!display_added) {
+ g_free (*cookie);
+ *cookie = NULL;
+ g_propagate_error (error, add_error);
+ return FALSE;
+ }
+
+ return TRUE;
+}
+
+gboolean
+gdm_display_access_file_add_display_with_cookie (GdmDisplayAccessFile *file,
+ GdmDisplay *display,
+ const char *cookie,
+ gsize cookie_size,
+ GError **error)
+{
+ Xauth auth_entry;
+ gboolean display_added;
+
+ g_return_val_if_fail (file != NULL, FALSE);
+ g_return_val_if_fail (file->path != NULL, FALSE);
+ g_return_val_if_fail (cookie != NULL, FALSE);
+
+ _get_auth_info_for_display (file, display,
+ &auth_entry.family,
+ &auth_entry.address_length,
+ &auth_entry.address,
+ &auth_entry.number_length,
+ &auth_entry.number,
+ &auth_entry.name_length,
+ &auth_entry.name);
+
+ auth_entry.data = (char *) cookie;
+ auth_entry.data_length = cookie_size;
+
+ /* FIXME: We should lock the file in case the X server is
+ * trying to use it, too.
+ */
+ if (!XauWriteAuth (file->fp, &auth_entry)
+ || fflush (file->fp) == EOF) {
+ g_set_error (error,
+ G_FILE_ERROR,
+ g_file_error_from_errno (errno),
+ "%s", g_strerror (errno));
+ display_added = FALSE;
+ } else {
+ display_added = TRUE;
+ }
+
+ /* If we wrote a FamilyLocal entry, we still want a FamilyWild
+ * entry, because it's more resiliant against hostname changes
+ *
+ */
+ if (auth_entry.family == FamilyLocal) {
+ auth_entry.family = FamilyWild;
+
+ if (XauWriteAuth (file->fp, &auth_entry)
+ && fflush (file->fp) != EOF) {
+ display_added = TRUE;
+ }
+ }
+
+ g_free (auth_entry.address);
+ g_free (auth_entry.number);
+ g_free (auth_entry.name);
+
+ return display_added;
+}
+
+void
+gdm_display_access_file_close (GdmDisplayAccessFile *file)
+{
+ char *auth_dir;
+
+ g_return_if_fail (file != NULL);
+ g_return_if_fail (file->fp != NULL);
+ g_return_if_fail (file->path != NULL);
+
+ errno = 0;
+ if (g_unlink (file->path) != 0) {
+ g_warning ("GdmDisplayAccessFile: Unable to remove X11 authority database '%s': %s",
+ file->path,
+ g_strerror (errno));
+ }
+
+ /* still try to remove dir even if file remove failed,
+ may have already been removed by someone else */
+ /* we own the parent directory too */
+ auth_dir = g_path_get_dirname (file->path);
+ if (auth_dir != NULL) {
+ errno = 0;
+ if (g_rmdir (auth_dir) != 0) {
+ g_warning ("GdmDisplayAccessFile: Unable to remove X11 authority directory '%s': %s",
+ auth_dir,
+ g_strerror (errno));
+ }
+ g_free (auth_dir);
+ }
+
+ g_free (file->path);
+ file->path = NULL;
+ g_object_notify (G_OBJECT (file), "path");
+
+ fclose (file->fp);
+ file->fp = NULL;
+}
+
+char *
+gdm_display_access_file_get_path (GdmDisplayAccessFile *access_file)
+{
+ return g_strdup (access_file->path);
+}
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