namespace.conf - the namespace configuration file


   The 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 an instance directory is set up and mounted. 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:


   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.

   mntopts=value - value of this flag is passed to the mount call when the
   tmpfs mount is done. It allows for example the specification of the
   maximum size of the tmpfs instance that is created by the mount call.
   See mount(8) for details.

   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 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 [arguments]

   This module also depends on setting the context.


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


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

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