Provided by: libpam-modules_0.99.7.1-5ubuntu6_i386 bug


       pam_namespace - PAM module for configuring namespace for a session

SYNOPSIS [debug] [unmnt_remnt] [unmnt_only] [require_selinux]
                        [gen_hash] [ignore_config_error]


       The pam_namespace PAM module sets up a private namespace for a session
       with polyinstantiated directories. A polyinstantiated directory
       provides a different instance of itself based on user name, or when
       using SELinux, user name, security context or both. If an executable
       script /etc/security/namespace.init exists, it is used to initialize
       the namespace every time a new instance directory is setup. The script
       receives the polyinstantiated directory path and the instance directory
       path as its arguments.

       The pam_namespace module disassociates the session namespace from the
       parent namespace. Any mounts/unmounts performed in the parent
       namespace, such as mounting of devices, are not reflected in the
       session namespace. To propagate selected mount/unmount events from the
       parent namespace into the disassociated session namespace, an
       administrator may use the special shared-subtree feature. For
       additional information on shared-subtree feature, please refer to the
       mount(8) man page and the shared-subtree description at and


          A lot of debug information is logged using syslog

          For programs such as su and newrole, the login session has already
          setup a polyinstantiated namespace. For these programs,
          polyinstantiation is performed based on new user id or security
          context, however the command first needs to undo the
          polyinstantiation performed by login. This argument instructs the
          command to first undo previous polyinstantiation before proceeding
          with new polyinstantiation based on new id/context

          For trusted programs that want to undo any existing bind mounts and
          process instance directories on their own, this argument allows them
          to unmount currently mounted instance directories

          If selinux is not enabled, return failure

          Instead of using the security context string for the instance name,
          generate and use its md5 hash.

          If a line in the configuration file corresponding to a
          polyinstantiated directory contains format error, skip that line
          process the next line. Without this option, pam will return an error
          to the calling program resulting in termination of the session.

          Instance parent directories by default are expected to have the
          restrictive mode of 000. Using this option, an administrator can
          choose to ignore the mode of the instance parent. This option should
          be used with caution as it will reduce security and isolation goals
          of the polyinstantiation mechanism.


       The session service is supported.


          Namespace setup was successful.

          Unexpected system error occurred while setting up namespace.

          Unexpected namespace configuration error occurred.


          Configuration file


       For the <service>s you need polyinstantiation (login for example) put
       the following line in /etc/pam.d/<service> as the last line for session

       session required [arguments]

       To use polyinstantiation with graphical display manager gdm, insert the
       following line, before exit 0, in /etc/gdm/PostSession/Default:


       This allows gdm to restart after each session and appropriately adjust
       namespaces of display manager and the X server. If polyinstantiation of
       /tmp is desired along with the graphical environment, then additional
       configuration changes are needed to address the interaction of X server
       and font server namespaces with their use of /tmp to create
       communication sockets. Please use the initialization script
       /etc/security/namespace.init to ensure that the X server and its
       clients can appropriately access the communication socket X0. Please
       refer to the sample instructions provided in the comment section of the
       instance initialization script /etc/security/namespace.init. In
       addition, perform the following changes to use graphical environment
       with polyinstantiation of /tmp:

                1. Disable the use of font server by commenting out "FontPath"
                   line in /etc/X11/xorg.conf. If you do want to use the font server
                   then you will have to augment the instance initialization
                   script to appropriately provide /tmp/.font-unix from the
                   polyinstantiated /tmp.
                2. Ensure that the gdm service is setup to use pam_namespace,
                   as described above, by modifying /etc/pam.d/gdm.
                3. Ensure that the display manager is configured to restart X server
                   with each new session. This default setup can be verified by
                   making sure that /usr/share/gdm/defaults.conf contains
                   "AlwaysRestartServer=true", and it is not overridden by


       namespace.conf(5), pam.d(8), mount(8), pam(8).


       The namespace setup scheme was designed by Stephen Smalley, Janak Desai
       and Chad Sellers. The pam_namespace PAM module was developed by Janak
       Desai <>, Chad Sellers <> and Steve
       Grubb <>.