Bug#259173: gdm: SecureSystemMenu is either too secure or too insecure

[Michael Piefel]

Package: gdm
Version: 2.6.0.3-1
Severity: important
Tags: security

gdm has a System Menu which offers options such as "Shut down the
computer" and "Edit gdm otions". Using gdm.conf's SecureSystemMenu
setting, this menu either requests the root password or it doesn't.

This leads to the unfortunate situation where either:
- Any user has to enter the root password to shut down the computer.
  IOW, they cannot, because I won't give them the password. They can cut
  the power, but that isn't good.
- Any user can change all of gdm's settings, including auto-login for a
  certain user and such. This opens a wide security hole.

At home (older gdm version) the settings menu requires a password,
shutting down doesn't. That's the way it should be. If shutting down has
to be protected by a password, this has to be a separate option.

-- System Information:
Debian Release: testing/unstable
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: i386 (i686)
Kernel: Linux 2.6.5-1-k7
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8

Versions of packages gdm depends on:
ii  adduser                   3.57           Add and remove users and groups
ii  debconf                   1.4.29         Debian configuration management sy
ii  dpkg                      1.10.22        Package maintenance system for Deb
ii  gksu                      1.2.0-2        graphical frontend to su
ii  gnome-session             2.6.2-3        The GNOME 2 Session Manager
ii  gnome-terminal [x-termina 2.6.1-4        The GNOME 2 terminal emulator appl
ii  libart-2.0-2              2.3.16-5       Library of functions for 2D graphi
ii  libatk1.0-0               1.6.1-2        The ATK accessibility toolkit
ii  libattr1                  2.4.16-1       Extended attribute shared library
ii  libbonobo2-0              2.6.2-4        Bonobo CORBA interfaces library
ii  libbonoboui2-0            2.6.1-1        The Bonobo UI library
ii  libc6                     2.3.2.ds1-13   GNU C Library: Shared libraries an
ii  libgconf2-4               2.6.2-1        GNOME configuration database syste
ii  libglade2-0               1:2.4.0-1      Library to load .glade files at ru
ii  libglib2.0-0              2.4.2-1        The GLib library of C routines
ii  libgnome2-0               2.6.1-8        The GNOME 2 library - runtime file
ii  libgnomecanvas2-0         2.6.1.1-2      A powerful object-oriented display
ii  libgnomeui-0              2.6.1.1-3      The GNOME 2 libraries (User Interf
ii  libgnomevfs2-0            2.6.1.1-4      The GNOME virtual file-system libr
ii  libgtk2.0-0               2.4.3-3        The GTK+ graphical user interface 
ii  libice6                   4.3.0.dfsg.1-6 Inter-Client Exchange library
ii  liborbit2                 1:2.10.2-1.1   libraries for ORBit2 - a CORBA ORB
ii  libpam-modules            0.76-22        Pluggable Authentication Modules f
ii  libpam-runtime            0.76-22        Runtime support for the PAM librar
ii  libpam0g                  0.76-22        Pluggable Authentication Modules l
ii  libpango1.0-0             1.4.0-4        Layout and rendering of internatio
ii  libpopt0                  1.7-4          lib for parsing cmdline parameters
ii  librsvg2-2                2.7.2-2        SAX-based renderer library for SVG
ii  libselinux1               1.14-1         SELinux shared libraries
ii  libsm6                    4.3.0.dfsg.1-6 X Window System Session Management
ii  libwrap0                  7.6.dbs-4      Wietse Venema's TCP wrappers libra
ii  libx11-6                  4.3.0.dfsg.1-6 X Window System protocol client li
ii  libxext6                  4.3.0.dfsg.1-6 X Window System miscellaneous exte
ii  libxml2                   2.6.10-3       GNOME XML library
ii  metacity [x-window-manage 1:2.8.1-3      A lightweight GTK2 based Window Ma
ii  rxvt [x-terminal-emulator 1:2.6.4-6      VT102 terminal emulator for the X 
ii  twm [x-window-manager]    4.3.0.dfsg.1-6 Tab window manager
ii  xbase-clients             4.3.0.dfsg.1-6 miscellaneous X clients
ii  xlibs                     4.3.0.dfsg.1-6 X Window System client libraries m
ii  xterm [x-terminal-emulato 4.3.0.dfsg.1-6 X terminal emulator
ii  zlib1g                    1:1.2.1.1-3    compression library - runtime

-- debconf information:
  gdm/daemon_name: /usr/bin/gdm
  shared/default-x-display-manager: gdm