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#!/bin/sh -e
# (C) 2008 Canonical Ltd.
# Author: Martin Pitt <martin.pitt@ubuntu.com>
# License: GPL v2 or later
# modified by David D Lowe and Thomas Detoux
#
# Setup user and temporary home directory for guest session.
# If this succeeds, this script needs to print the username as the last line to
# stdout.
export TEXTDOMAINDIR=/usr/share/locale-langpack
export TEXTDOMAIN=lightdm
# set the system wide locale for gettext calls
if [ -f /etc/default/locale ]; then
. /etc/default/locale
LANGUAGE=
export LANG LANGUAGE
fi
add_account ()
{
local temp_home=$(mktemp -td guest-XXXXXX)
HOME=$(echo ${temp_home} | tr '[:upper:]' '[:lower:]')
USER=$(echo ${HOME} | sed 's/\(.*\)guest/guest/')
[ ${HOME} != ${temp_home} ] && mv ${temp_home} ${HOME}
# if ${USER} already exists, it must be a locked system account with no existing
# home directory
if PWSTAT=$(passwd -S ${USER}) 2>/dev/null; then
if [ $(echo ${PWSTAT} | cut -f2 -d' ') != L ]; then
echo "User account ${USER} already exists and is not locked"
exit 1
fi
PWENT=$(getent passwd ${USER}) || {
echo "getent passwd ${USER} failed"
exit 1
}
GUEST_UID=$(echo ${PWENT} | cut -f3 -d:)
if [ ${GUEST_UID} -ge 500 ]; then
echo "Account ${USER} is not a system user"
exit 1
fi
HOME=$(echo ${PWENT} | cut -f6 -d:)
if [ ${HOME} != / ] && [ ${HOME#/tmp} = ${HOME} ] && [ -d ${HOME} ]; then
echo "Home directory of ${USER} already exists"
exit 1
fi
else
# does not exist, so create it
useradd --system --home-dir / --comment $(gettext "Guest") --user-group --shell /bin/bash ${USER} || {
rm -rf ${HOME}
exit 1
}
fi
dist_gs=/usr/share/lightdm/guest-session
site_gs=/etc/guest-session
# create temporary home directory
mount -t tmpfs -o mode=700,uid=${USER} none ${HOME} || {
rm -rf ${HOME}
exit 1
}
if [ -d ${site_gs}/skel ] && [ -n $(find ${site_gs}/skel -type f) ]; then
# Only perform union-mounting if BindFS is available
if [ -x /usr/bin/bindfs ]; then
bindfs_mount=true
# Try OverlayFS first
if modinfo -n overlay >/dev/null 2>&1; then
mkdir ${HOME}/upper ${HOME}/work
chown ${USER}:${USER} ${HOME}/upper ${HOME}/work
mount -t overlay -o lowerdir=${dist_gs}/skel:${site_gs}/skel,upperdir=${HOME}/upper,workdir=${HOME}/work overlay ${HOME} || {
umount ${HOME}
rm -rf ${HOME}
exit 1
}
# If OverlayFS is not available, try AuFS
elif [ -x /sbin/mount.aufs ]; then
mount -t aufs -o br=${HOME}:${dist_gs}/skel:${site_gs}/skel none ${HOME} || {
umount ${HOME}
rm -rf ${HOME}
exit 1
}
# If none of them is available, fall back to copy over
else
cp -rT ${site_gs}/skel/ ${HOME}
cp -rT ${dist_gs}/skel/ ${HOME}
chown -R ${USER}:${USER} ${HOME}
bindfs_mount=false
fi
if ${bindfs_mount}; then
# Wrap ${HOME} in a BindFS mount, so that
# ${USER} will be seen as the owner of ${HOME}'s contents.
bindfs -u ${USER} -g ${USER} ${HOME} ${HOME} || {
umount ${HOME} # union mount
umount ${HOME} # tmpfs mount
rm -rf ${HOME}
exit 1
}
fi
# If BindFS is not available, just fall back to copy over
else
cp -rT ${site_gs}/skel/ ${HOME}
cp -rT ${dist_gs}/skel/ ${HOME}
chown -R ${USER}:${USER} ${HOME}
fi
else
cp -rT /etc/skel/ ${HOME}
cp -rT ${dist_gs}/skel/ ${HOME}
chown -R ${USER}:${USER} ${HOME}
fi
usermod -d ${HOME} ${USER}
# setup session
su ${USER} -c "env HOME=${HOME} site_gs=${site_gs} ${dist_gs}/setup.sh"
echo ${USER}
}
remove_account ()
{
GUEST_USER=${1}
PWENT=$(getent passwd ${GUEST_USER}) || {
echo "Error: invalid user ${GUEST_USER}"
exit 1
}
GUEST_UID=$(echo ${PWENT} | cut -f3 -d:)
GUEST_HOME=$(echo ${PWENT} | cut -f6 -d:)
SYS_UID_MIN=$(cat /etc/login.defs | grep SYS_UID_MIN | awk '{print $2}')
SYS_UID_MAX=$(cat /etc/login.defs | grep SYS_UID_MAX | awk '{print $2}')
if [ ${GUEST_UID} -lt ${SYS_UID_MIN} ] || [ ${GUEST_UID} -gt ${SYS_UID_MAX} ]; then
echo "Error: user ${GUEST_USER} is not a system user."
exit 1
fi
if [ ${GUEST_HOME} = ${GUEST_HOME#/tmp/} ]; then
echo "Error: home directory ${GUEST_HOME} is not in /tmp/."
exit 1
fi
# kill all remaining processes
while ps h -u ${GUEST_USER} >/dev/null; do
killall -9 -u ${GUEST_USER} || true
sleep 0.2;
done
umount ${GUEST_HOME} || umount -l ${GUEST_HOME} || true # BindFS mount
umount ${GUEST_HOME} || umount -l ${GUEST_HOME} || true # union mount
umount ${GUEST_HOME} || umount -l ${GUEST_HOME} || true # tmpfs mount
rm -rf ${GUEST_HOME}
# remove leftovers in /tmp
find /tmp -mindepth 1 -maxdepth 1 -uid ${GUEST_UID} -print0 | xargs -0 rm -rf || true
# remove possible /media/guest-XXXXXX folder
if [ -d /media/${GUEST_USER} ]; then
for dir in $(find /media/${GUEST_USER} -mindepth 1 -maxdepth 1); do
umount ${dir} || true
done
rmdir /media/${GUEST_USER} || true
fi
userdel ${GUEST_USER}
}
case ${1} in
add)
add_account
;;
remove)
if [ -z ${2} ] ; then
echo "Usage: ${0} remove [account]"
exit 1
fi
remove_account ${2}
;;
*)
echo "Usage: ${0} add|remove"
exit 1
esac
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