pam_namespace - PAM module for configuring namespace for a session
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]
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 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.
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.
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, 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
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
The namespace setup scheme was designed by Stephen Smalley, Janak Desai and Chad Sellers. The pam_namespace PAM module was developed by Janak Desai <email@example.com>, Chad Sellers <firstname.lastname@example.org> and Steve Grubb <email@example.com>. Additional improvements by Xavier Toth <firstname.lastname@example.org> and Tomas Mraz <email@example.com>.