PAM_NAMESPACE(8)	       Linux-PAM Manual		      PAM_NAMESPACE(8)

NAME
       pam_namespace - PAM module for configuring namespace for a session

SYNOPSIS
       pam_namespace.so [debug] [unmnt_remnt] [unmnt_only] [require_selinux]
			[gen_hash] [ignore_config_error]
			[ignore_instance_parent_mode] [unmount_on_close]
			[use_current_context] [use_default_context]
			[mount_private]

DESCRIPTION
       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 instance directory after it is set up and mounted on the
       polyinstantiated directory. The script receives the polyinstantiated
       directory path, the instance directory path, flag whether the instance
       directory was newly created (0 for no, 1 for yes), and the user name as
       its arguments. The script is invoked with full root privileges and
       accessing the instance directory in this context needs to be done with
       caution, as it is controlled by the unprivileged user for which it has
       been created.

       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
       http://lwn.net/Articles/159077 and http://lwn.net/Articles/159092.

OPTIONS
       debug
	   A lot of debug information is logged using syslog

       unmnt_remnt
	   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

       unmnt_only
	   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

       require_selinux
	   If selinux is not enabled, return failure

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

       ignore_config_error
	   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.

       ignore_instance_parent_mode
	   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.

       unmount_on_close
	   Explicitly unmount the polyinstantiated directories instead of
	   relying on automatic namespace destruction after the last process
	   in a namespace exits. This option should be used only in case it is
	   ensured by other means that there cannot be any processes running
	   in the private namespace left after the session close. It is also
	   useful only in case there are multiple pam session calls in
	   sequence from the same process.

       use_current_context
	   Useful for services which do not change the SELinux context with
	   setexeccon call. The module will use the current SELinux context of
	   the calling process for the level and context polyinstantiation.

       use_default_context
	   Useful for services which do not use pam_selinux for changing the
	   SELinux context with setexeccon call. The module will use the
	   default SELinux context of the user for the level and context
	   polyinstantiation.

       mount_private
	   This option can be used on systems where the / mount point or its
	   submounts are made shared (for example with a mount --make-rshared
	   / command). The module will mark the whole directory tree so any
	   mount and unmount operations in the polyinstantiation namespace are
	   private. Normally the pam_namespace will try to detect the shared /
	   mount point and make the polyinstantiated directories private
	   automatically. This option has to be used just when only a subtree
	   is shared and / is not.

	   Note that mounts and unmounts done in the private namespace will
	   not affect the parent namespace if this option is used or when the
	   shared / mount point is autodetected.

MODULE TYPES PROVIDED
       Only the session module type is provided. The module must not be called
       from multithreaded processes.

RETURN VALUES
       PAM_SUCCESS
	   Namespace setup was successful.

       PAM_SERVICE_ERR
	   Unexpected system error occurred while setting up namespace.

       PAM_SESSION_ERR
	   Unexpected namespace configuration error occurred.

FILES
       /etc/security/namespace.conf
	   Main configuration file

       /etc/security/namespace.d
	   Directory for additional configuration files

       /etc/security/namespace.init
	   Init script for instance directories

EXAMPLES
       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
       group:

       session required pam_namespace.so [arguments]

       To use polyinstantiation with graphical display manager gdm, please
       refer to gdm's documentation.

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

AUTHORS
       The namespace setup scheme was designed by Stephen Smalley, Janak Desai
       and Chad Sellers. The pam_namespace PAM module was developed by Janak
       Desai <janak@us.ibm.com>, Chad Sellers <csellers@tresys.com> and Steve
       Grubb <sgrubb@redhat.com>. Additional improvements by Xavier Toth
       <txtoth@gmail.com> and Tomas Mraz <tmraz@redhat.com>.

Linux-PAM			  06/19/2025		      PAM_NAMESPACE(8)