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NAMESPACE.CONF(5)              Linux-PAM Manual              NAMESPACE.CONF(5)

       namespace.conf - the namespace configuration file

       The pam_namespace.so module allows setup of private namespaces with
       polyinstantiated directories. Directories can be polyinstantiated based
       on user name or, in the case of SELinux, user name, sensitivity level
       or complete security context. 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 /etc/security/namespace.conf file specifies which directories are
       polyinstantiated, how they are polyinstantiated, how instance
       directories would be named, and any users for whom polyinstantiation
       would not be performed.

       When someone logs in, the file namespace.conf is scanned. Comments are
       marked by # characters. Each non comment line represents one
       polyinstantiated directory. The fields are separated by spaces but can
       be quoted by " characters also escape sequences \b, \n, and \t are
       recognized. The fields are as follows:

       polydir instance_prefix method list_of_uids

       The first field, polydir, is the absolute pathname of the directory to
       polyinstantiate. The special string $HOME is replaced with the user's
       home directory, and $USER with the username. This field cannot be

       The second field, instance_prefix is the string prefix used to build
       the pathname for the instantiation of <polydir>. Depending on the
       polyinstantiation method it is then appended with "instance
       differentiation string" to generate the final instance directory path.
       This directory is created if it did not exist already, and is then bind
       mounted on the <polydir> to provide an instance of <polydir> based on
       the <method> column. The special string $HOME is replaced with the
       user's home directory, and $USER with the username. This field cannot
       be blank.

       The third field, method, is the method used for polyinstantiation. It
       can take these values; "user" for polyinstantiation based on user name,
       "level" for polyinstantiation based on process MLS level and user name,
       "context" for polyinstantiation based on process security context and
       user name, "tmpfs" for mounting tmpfs filesystem as an instance dir,
       and "tmpdir" for creating temporary directory as an instance dir which
       is removed when the user's session is closed. Methods "context" and
       "level" are only available with SELinux. This field cannot be blank.

       The fourth field, list_of_uids, is a comma separated list of user names
       for whom the polyinstantiation is not performed. If left blank,
       polyinstantiation will be performed for all users. If the list is
       preceded with a single "~" character, polyinstantiation is performed
       only for users in the list.

       The method field can contain also following optional flags separated by
       : characters.

       create=mode,owner,group - create the polyinstantiated directory. The
       mode, owner and group parameters are optional. The default for mode is
       determined by umask, the default owner is the user whose session is
       opened, the default group is the primary group of the user.

       iscript=path - path to the instance directory init script. The base
       directory for relative paths is /etc/security/namespace.d.

       noinit - instance directory init script will not be executed.

       shared - the instance directories for "context" and "level" methods
       will not contain the user name and will be shared among all users.

       The directory where polyinstantiated instances are to be created, must
       exist and must have, by default, the mode of 0000. The requirement that
       the instance parent be of mode 0000 can be overridden with the command
       line option ignore_instance_parent_mode

       In case of context or level polyinstantiation the SELinux context which
       is used for polyinstantiation is the context used for executing a new
       process as obtained by getexeccon. This context must be set by the
       calling application or pam_selinux.so module. If this context is not
       set the polyinstatiation will be based just on user name.

       The "instance differentiation string" is <user name> for "user" method
       and <user name>_<raw directory context> for "context" and "level"
       methods. If the whole string is too long the end of it is replaced with
       md5sum of itself. Also when command line option gen_hash is used the
       whole string is replaced with md5sum of itself.

       These are some example lines which might be specified in

                 # The following three lines will polyinstantiate /tmp,
                 # /var/tmp and user's home directories. /tmp and /var/tmp
                 # will be polyinstantiated based on the security level
                 # as well as user name, whereas home directory will be
                 # polyinstantiated based on the full security context and user name.
                 # Polyinstantiation will not be performed for user root
                 # and adm for directories /tmp and /var/tmp, whereas home
                 # directories will be polyinstantiated for all users.
                 # Note that instance directories do not have to reside inside
                 # the polyinstantiated directory. In the examples below,
                 # instances of /tmp will be created in /tmp-inst directory,
                 # where as instances of /var/tmp and users home directories
                 # will reside within the directories that are being
                 # polyinstantiated.
                 /tmp     /tmp-inst/               level      root,adm
                 /var/tmp /var/tmp/tmp-inst/       level      root,adm
                 $HOME    $HOME/$USER.inst/inst- context

       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 pam_namespace.so [arguments]

       This module also depends on pam_selinux.so setting the context.

       pam_namespace(8), pam.d(5), pam(7)

       The namespace.conf manual page was written by Janak Desai
       <janakATus.com>. More features added by Tomas Mraz

Linux-PAM Manual                  07/27/2008                 NAMESPACE.CONF(5)