auto_home

#!/bin/bash

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

# Copyright 2019 Joyent, Inc.

# Inspired by
# http://znogger.blogspot.com/2010/05/solaris-automatic-creation-of-home-dirs.html

# To use this script to automatically create home directories, either import
# autofs_local.ldif into your LDAP DIT or add the following to
# `/etc/auto_master`:
#
#     /home /etc/auto_homedir

if [[ -n "$TRACE" ]]; then
        export PS4='[\D{%FT%TZ}] ${BASH_SOURCE}:${LINENO}: ${FUNCNAME[0]:+${FUNCNAME[0]}(): }'
        set -o xtrace
fi

# Configurable variables
# Ideally, this should be in a config file.
homebase="home"                 # Required
exportbase="export/${homebase}" # Required
zpool="auto"                    # Delete this if not using
delegated_base=""               # Delete this if not using

# Set some reasonable restrictions on user zfs datasets
zfs_options=( -o devices=off -o setuid=off -o snapshot_limit=16 )
zfs_local_allow="diff,mount,rollback,snapshot"
zfs_descendent_allow="clone,create,destroy,rename"

# Non-configurable variables
user="$1"
homedir="/${homebase:?}/${user:?}"
exportdir="/${exportbase:?}/${user:?}"

##
## Exit early if possible
##
if ! [[ -d "/$homebase" ]]; then
        : $homebase does not exist
        exit 0
fi

# Get user details from passwd database
IFS=: read -r -a ent <<< $(getent passwd "$user")

if [[ -z "${ent[0]}" ]]; then
        : User "$user" does not exist
        exit 0
fi
if ! [[ "${ent[5]}" == "$homedir" ]]; then
        : "${ent[5]}" is not a child of "/$homebase"
        exit 0
fi

# Check if homedir exists
if [[ -d "$exportdir" ]]; then
        : $exportdir already exists
        echo "localhost:$exportdir"
        exit 0
fi

##
## Create homedir
##
if [[ -n "$zpool" ]]; then
        if [[ "$zpool" == "auto" ]]; then
                zfshome="$(zfs list -H -o mountpoint,name | awk '$1~mount { print $2 }' mount="^/${exportbase:?}$")"
        else
                zonename="$(zonename)"
                case "$zonename" in
                        global)
                                zfsbase="${zpool:?}"
                                ;;
                        *)
                                zfsbase="${zpool:?}/${zonename}/${delegated_base}"
                                ;;
                esac
                zfshome="${zfsbase}/${homebase}"
        fi
fi

# If $zfshome exists create a child dataset, otherwise just make a directory.
if [[ -n "$zfshome" ]]; then
        if ! zfs list $zfshome 2> /dev/null > /dev/null; then
                zfs create -o mountpoint="/$exportbase" "${zfshome}"
        fi
        if zfs create "${zfs_options[@]}" "${zfshome}/${user}"; then
                zfs allow "$user" "$zfs_local_allow" "${zfshome}/${user}"
                zfs allow -d "$user" "$zfs_descendent_allow" "${zfshome}/${user}"
        fi
fi
[[ -d "$exportdir" ]] || mkdir -p "$exportdir"

# Populate initial contents of home directory
rsync -a "/etc/skel/" "${exportdir}/"
chown -Rh "${ent[2]}:${ent[3]}" "$exportdir"

echo "localhost:$exportdir"