Men at benches on left finishing configurations while other workers wait patiently.

VirtualExam (vx)
vx.conf

[global]

new directory permissions = 0755

tmp directory permissions = 01777

[bind mounts]

/lib
/usr/lib
/usr/share

[special mounts]

/dev = devtmpfs
/dev/pts = devpts
#/dev/shm = tmpfs
/proc = proc

[hard links]

/bin/rm
/bin/ls
/bin/ps
/bin/cp
/bin/cat
/bin/echo
/bin/more
/bin/less
/bin/grep
/bin/fgrep
/bin/sleep
/bin/sh
/bin/bash
/usr/bin/id
/usr/bin/env

/etc/hosts
/etc/ld.so.cache
/etc/localtime
/etc/login.defs
/etc/resolv.conf

# Testing
/bin/su
/bin/netstat
/usr/bin/strace
/usr/bin/nslookup
/usr/bin/telnet
/usr/bin/telnet.netkit

[create directories]

/usr
/bin
/sbin
/etc
/usr/bin
/var
/var/lib

A vx.conf file controls what file system objects (directories, soft links, files, devices and sockets (amongst possibly other things) are imported into a gaol.

It does NOT have anything to do with the home directory set up in the gaol for the user/student, or with the user's UID, GID, etc.

There are two (or more) vx.conf files which are or can be used when setting up a gaol.

The first, and main instance, must exist and is in /home/virtualexam/etc.

Subsequent instances are optional and allow customisation for a particular class's exams. When used, these are:

• /home/<class-exam-account>/etc/vx.conf, and/or
• All files (which can be soft-linked) in the directory /home/<class-exam-account>/etc/vx.conf.d.

In line with the guiding principle of a picture is worth a thousand words, an example file is shown to the right.

The contents of the file include comments (starting with '#'), blank lines, headings and file system object definitions. All file system object definitions must have absolute paths (i.e., they must begin with "/").

• [global]
  • new directory permissions = the permissions assigned to created directories in the gaol. All directories are created [group]owned by root.
  • tmp directory permissions = permissions assigned to /tmp. It is created [group]owned by root.
• [bind mounts] - the path is bind-mounted from the host file system to the same location in the goal. Useful for making directories like /lib or /usr/include appear in the gaol without needing to be copied.
• [special mounts] - used for /dev, /proc, etc. Consists of path-in-gaol and file system type.
• [hard links] - the file system object in the host file system is hard linked to the same location in the gaol. Useful for individual files, soft links and sockets.
• [create directories] - the directory is created in the gaol. See new directory permissions above.

Note: the [global] heading may only appear in the main file instance.

Each heading may appear multiple times. This allows imported file system objects to be grouped together by function (e.g. such as all directories, hard links and bind mounts required to allow Firefox to run).