Tomb/src/tomb

#!/bin/zsh
#
# Tomb, the Crypto Undertaker
#
# a tool to easily operate file encryption of private and secret data
#
# Copyleft (C) 2007-2011 Denis Roio <jaromil@dyne.org>
#
# This source  code is free  software; you can redistribute  it and/or
# modify it under the terms of  the GNU Public License as published by
# the Free  Software Foundation; either  version 3 of the  License, or
# (at your option) any later version.
#
# This source code is distributed in  the hope that it will be useful,
# but  WITHOUT ANY  WARRANTY;  without even  the  implied warranty  of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# Please refer to the GNU Public License for more details.
#
# You should have received a copy of the GNU Public License along with
# this source code; if not, write to:
# Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

VERSION=1.0
DATE=Feb/2011
TOMBEXEC=$0

# PATH=/usr/bin:/usr/sbin:/bin:/sbin   

# standard output message routines
# it's always useful to wrap them, in case we change behaviour later
notice() { if ! [ $QUIET ]; then echo "[*] $1" >&2; fi }
act()    { if ! [ $QUIET ]; then echo " .  $1" >&2; fi }
error()  { if ! [ $QUIET ]; then echo "[!] $1" >&2; fi }
func()   { if [ $DEBUG ]; then   echo "[D] $1" >&2; fi }

# which dd command to use
which dcfldd > /dev/null
if [ $? = 0 ]; then
    DD="dcfldd"
else
    DD=dd
fi

# which wipe command to use
which wipe > /dev/null
if [ $? = 0 ]; then
    WIPE=(wipe -f -s)
else
    WIPE=(rm -f)
fi

# check for filesystem creation progs
which mkfs.ext4 > /dev/null
if [ $? = 0 ]; then
    MKFS=(mkfs.ext4 -q -F -j -L)
else
    MKFS=(mkfs.ext3 -q -F -j -L)
fi

# check for sudo
which sudo > /dev/null
if [ $? != 0 ]; then
    error "Cannot find sudo. Please install it"
    exit 1
fi

# safe dir creation function
safe_dir() {
    dir="/tmp/$1.$RANDOM.$RANDOM.$$"
    (umask 077 && mkdir "$dir") || echo "-1"
    echo "$dir"
}

# we use pinentry now
# comes from gpg project and is much more secure
# it also conveniently uses the right toolkit
ask_password() {

    # pinentry has no custom icon setting
    # so we need to temporary modify the gtk theme
    if [ -r /usr/local/share/themes/tomb/gtk-2.0-key/gtkrc ]; then
	GTK2_RC=/usr/local/share/themes/tomb/gtk-2.0-key/gtkrc
    elif [ -r /usr/share/themes/tomb/gtk-2.0-key/gtkrc ]; then
	GTK2_RC=/usr/share/themes/tomb/gtk-2.0-key/gtkrc
    fi

    cat <<EOF | GTK2_RC_FILES=${GTK2_RC} pinentry | awk '/^D/ { print $2 }'
OPTION ttyname=$TTY
OPTION lc-ctype=$LANG
SETTITLE Insert tomb password
SETDESC Open tomb: $1
SETPROMPT Password:
GETPIN
EOF

}

# drop privileges
exec_as_user() {

    if ! [ $SUDO_USER ]; then
	exec $@[@]
	return $?
    fi
    
    func "exec_as_user '$SUDO_USER': ${(f)@}"
    sudo -u $SUDO_USER "${@[@]}"
    return $?
}


# escalate privileges
check_priv() {
    id | grep root > /dev/null
    if [ $? != 0 ]; then
	func "Using sudo for root execution of 'tomb ${(f)ARGS}'"
	    # check if sudo has a timestamp active
	sudok=false
	sudo -n ${TOMBEXEC} 2> /dev/null
	if [ $? != 0 ]; then # if not then ask a password
	    cat <<EOF | pinentry | awk '/^D/ { print $2 }' | sudo -S -v
OPTION ttyname=$TTY
OPTION lc-ctype=$LANG
SETTITLE Super user privileges required
SETDESC Sudo execution of Tomb ${ARGS[@]}
SETPROMPT Insert your USER password:
GETPIN
EOF
	fi
	sudo "${TOMBEXEC}" ${(s: :)ARGS}
	exit $?
    fi # are we root already
    return 0
}

get_arg_tomb() {
# set up variables to be used by caller:
# tombfile - filename without path
# tombdir  - directory where the tomb is
# tombname - name of the tomb (filename without extension)
# the full path is made with $tombdir/$tombfile
    if [ -z $1 ]; then
	error "internal: get_arg_tomb called without argument"
	return 1
    fi

    arg=${1}
    if ! [ -r ${arg} ]; then
	error "file not found: $arg"
	return 1
    fi

    tombfile=`basename $arg`
    tombdir=`dirname $arg`

    file ${tombdir}/${tombfile} | grep -i 'luks encrypted file' 2>&1 >/dev/null
    if [ $? != 0 ]; then
	error "$arg is not a valid tomb file, operation aborted"
	return 1
    fi

    tombname=${tombfile%%\.*}
    act "tomb found: ${tombdir}/${tombfile}"
    # now check if the key is kept beside or in args
    # we use the extension .key

    # the problem with .tomb.gpg is that decoding by hand using gpg it
    # can override the tomb contents if the key is in the same
    # directory than the tomb
    if [ $KEY ]; then
	tombkey=$KEY # commandline -k flag
	act "tomb key specified manually: $tombkey"
    elif [ -r ${tombdir}/${tombname}.tomb.key ]; then
	tombkey=${tombdir}/${tombname}.tomb.key
	act "key found for tomb '${tombname}': ${tombkey}"
    else
	error "key not found for tomb '${tombname}'"
	return 1
    fi
    return 0
}

usage() {
	cat <<EOF
Tomb $VERSION - a strong and gentle undertaker for your secrets

 Copyright (C) 2007-2011 Dyne.org Foundation, License GNU GPL v3+
 This is free software: you are free to change and redistribute it
 The latest Tomb sourcecode is published on <http://tomb.dyne.org>

Syntax: tomb [options] command [file] [place]

Commands:

 create     create a new tomb FILE and its keys
 open       open an existing tomb FILE on PLACE
 close      closes the tomb open on PLACE
 bury       hide a tomb key FILE inside a jpeg PLACE
 exhume     extract a tomb key FILE from a jpeg PLACE

Options:

 -s     size of the tomb file when creating one (in MB)
 -k     path to the key to use for opening a tomb
 -n     don't process the hooks found in tomb

 -h     print this help
 -v     version information for this tool
 -q     run quietly without printing informations
 -D     print debugging information at runtime

For more informations on Tomb read the manual: man tomb
Please report bugs on <http://bugs.dyne.org>.
EOF
}

############################
### main()
###

echo $@ | grep '\-D' 2>&1 > /dev/null
if [ $? = 0 ]; then
fi

ARGS=$@[@]

OPTS=`getopt -o hvqDs:k:n -n 'tomb' -- "$@"`
while true; do
    case "$1" in
	-h)
		usage
		exit 0 ;;
	-v)
	    notice "Tomb  -  simple commandline tool for encrypted storage"
	    act "version $VERSION ($DATE) by Jaromil @ dyne.org"
	    # print out the GPL license in this file
	    act ""
	    cat $0 | awk '
BEGIN { license=0 }
/^# This source/  { license=1 }
{ if(license==1) print " " $0 }
/MA 02139, USA.$/ { license=0 }
'
	    act ""
	    exit 0 ;;
	-q) QUIET=1; shift 1 ;;
	-D)
	    echo "[D] Tomb invoked with args \"${(f)@}\" "
	    echo "[D] running on `date`"
	    DEBUG=1; shift 1 ;;
        -s) SIZE=$2; shift 2 ;;
	-k) KEY=$2; shift 2 ;;
	-n) NOBIND=1; shift 1 ;;
	--) shift; break ;;
	*)  CMD=$1;
	    FILE=$2; MOUNT=$3; # compat with old args
	    CMD2=${2}; CMD3=${3}; break ;;
    esac
done

if ! [ $CMD ]; then
    error "first argument missing, use -h for help"
    exit 0
fi

func "Tomb command: $CMD $CMD2 $CMD3"

create_tomb() {

    if ! [ ${CMD2} ]; then
	error "no tomb name specified for creation"
	return 1
    fi

    tombfile=`basename ${CMD2}`
    tombdir=`dirname ${CMD2}`
    # make sure the file has a .tomb extension
    tombname=${tombfile%%\.*}
    tombfile=${tombname}.tomb

    if [ -e ${tombdir}/${tombfile} ]; then
        error "tomb exists already. I'm not digging here:"
	ls -lh ${tombdir}/${tombfile}
        return 1
    fi

    notice "Creating a new tomb in ${tombdir}/${tombfile}"

    if [ -z $SIZE ]; then
	if [ $CMD3 ]; then
	    tombsize=${CMD3}
	else
	    act "No size specified, summoning the Tomb Undertaker to guide us in the creation."
	    "$TOMBOPENEXEC" &
	    wait $!
	    return 0
	fi
    else
	tombsize=${SIZE}
    fi

    tombsize_4k=`expr $tombsize \* 1000 / 4`
    act "Generating ${tombfile} of ${tombsize}Mb (${tombsize_4k} blocks of 4Kb)"
    $DD if=/dev/urandom bs=4k count=${tombsize_4k} of=${tombdir}/${tombfile}
    
    if [ $? = 0 -a -e ${tombdir}/${tombfile} ]; then
	act "OK: `ls -lh ${tombdir}/${tombfile}`"
    else
	error "Error creating the tomb ${tombdir}/${tombfile}, operation aborted."
	exit 1
    fi

    nstloop=`losetup -f` # get the number for next loopback device
    losetup -f ${tombdir}/${tombfile} # allocates the next loopback for our file

    # create the keyfile in tmpfs so that we leave less traces in RAM
    keytmp=`safe_dir tomb`
    if [ "$keytmp" = "-1" ]; then
	error "error creating temp dir"
        exit 1
    fi
    #rm -f $keytmp
    # ?????? creo, cancello e ricreo ??????
    #mkdir -p $keytmp
    mount tmpfs "${keytmp}" -t tmpfs -o size=1m
    if [ $? != 0 ]; then
	error "cannot mount tmpfs filesystem in volatile memory"
	error "operation aborted."
	losetup -d $nstloop
	rm -r "${keytmp}"
	exit 1
    fi
    act "Generating secret key..."
    act "this operation takes time, keep using this computer on other tasks,"
    act "once done you will be asked to choose a password for your tomb."
    touch ${keytmp}/tomb.tmp
    chmod 0600 ${keytmp}/tomb.tmp
    $DD bs=1 count=256 if=/dev/random of=${keytmp}/tomb.tmp
    if ! [ -r ${keytmp}/tomb.tmp ]; then
	error "cannot generate encryption key, operation aborted."
	umount ${keytmp}
	losetup -d $nstloop
	rm -r $keytmp
	exit 1
    fi
	
    notice "Setup your secret key file ${tombname}.tomb.key"

    # here user is prompted for key password
    for c in 1 2 3; do
	# 3 tries to write two times a matching password
	tombpass=`exec_as_user ${TOMBEXEC} askpass ${tombname}`
	tombpasstmp=$tombpass
	tombpass=`exec_as_user ${TOMBEXEC} askpass "${tombname} (again)"`
	if [ "$tombpasstmp" = "$tombpass" ]; then
	    break;
	fi
	unset tombpasstmp
	unset tombpass
    done

    if [ -z $tombpass ]; then
	error "passwords don't match, aborting operation"
	umount ${keytmp}
	losetup -d $nstloop
	rm -r $keytmp
	exit 1
    fi

    
    echo "${tombpass}" | gpg \
	--openpgp --batch --no-options --no-tty --passphrase-fd 0 2>/dev/null \
	-o "${tombdir}/${tombname}.tomb.key" -c -a ${keytmp}/tomb.tmp

    # if [ $? != 0 ]; then
    # 	error "setting password failed: gnupg returns 2"
    # 	umount ${keytmp}
    # 	losetup -d $nstloop
    # 	rm -r $keytmp
    # 	exit 1
    # fi
    
    act "formatting Luks mapped device"
        # we use aes-cbc-essiv with sha256
        # for security, performance and compatibility
    cryptsetup --batch-mode \
	--cipher aes-cbc-essiv:sha256 --key-size 256 \
	luksFormat ${nstloop} ${keytmp}/tomb.tmp

    if ! [ $? = 0 ]; then
	act "operation aborted."
	exit 0
    fi
     
    cryptsetup --key-file ${keytmp}/tomb.tmp --cipher aes luksOpen ${nstloop} tomb.tmp
    ${WIPE[@]} ${keytmp}/tomb.tmp
    umount ${keytmp}
    rm -r ${keytmp}

 #    cryptsetup luksDump ${nstloop}

    act "formatting your Tomb with Ext3/Ext4 filesystem"
 
    ${MKFS} ${tombname} /dev/mapper/tomb.tmp

    if [ $? != 0 ]; then
	error "Tomb format returns error"
	error "your tomb ${tombfile} maybe corrupt"
    fi

    sync

    cryptsetup luksClose tomb.tmp
    losetup -d ${nstloop}

    act "done creating $tombname encrypted storage (using Luks dm-crypt AES/SHA256)"
    notice "Your tomb is ready in ${tombdir}/${tombfile} and secured with key ${tombname}.tomb.key"

}


mount_tomb() {
    get_arg_tomb $CMD2
    if [ $? != 0 ]; then
	error "operation aborted."
	return 1
    fi

    if ! [ $CMD3 ]; then
	tombmount=/media/${tombfile}
	act "mountpoint not specified, using default: $tombmount"
    elif ! [ -x $CMD3 ]; then
	error "mountpoint $CMD3 doesn't exist, operation aborted."
	if [ -n "$usbkey_mount" ]; then
	    umount $usbkey_mount
	    rmdir  $usbkey_mount
	    unset usbkey_mount
	fi
	return 1
    else
	tombmount=$CMD3
    fi

    notice "mounting $tombfile on mountpoint $tombmount"

    # we need root from here on
    mkdir -p $tombmount
    
    nstloop=`losetup -f`
    if [ $? = 255 ]; then
        error "too many tomb opened. Please close any of them to open another tomb"
	exit 1
    fi
    losetup -f ${tombdir}/${tombfile}
    
    act "check for a valid LUKS encrypted device"
    cryptsetup isLuks ${nstloop}
    if [ $? != 0 ]; then
 # is it a LUKS encrypted nest? see cryptsetup(1)
	error "$tombfile is not a valid Luks encrypted storage file"
	$norm || rmdir $tombmount 2>/dev/null
	return 1
    fi

    # save date of mount in minutes since 1970
    mapdate="`date +%s`"
    mapdate="`echo ${mapdate}/60 | bc -l | cut -d. -f1`"
    
    mapper="tomb.${tombname}.${mapdate}.`basename $nstloop`"

    keyname=`basename $tombkey | cut -d. -f1`

    notice "Password is required for key ${keyname}"
    for c in 1 2 3; do
	
	if [ $c = 1 ]; then
	    tombpass=`exec_as_user ${TOMBEXEC} askpass ${keyname}`
	else
	    tombpass=`exec_as_user ${TOMBEXEC} askpass "$keyname (retry $c)"`
	fi
	echo "${tombpass}" \
	    | gpg --batch --passphrase-fd 0 --no-tty --no-options \
	          -d "${tombkey}" 2> /dev/null \
	    | cryptsetup --key-file - luksOpen ${nstloop} ${mapper}
	
	unset tombpass
	
	if [ -r /dev/mapper/${mapper} ]; then
	    break;  # password was correct
	fi
	
    done
    
    if ! [ -r /dev/mapper/${mapper} ]; then
	error "failure mounting the encrypted file"
	losetup -d ${nstloop}
	$norm || rmdir ${tombmount} 2>/dev/null
	return 1
    fi
    
    act "encrypted storage filesystem check"
    fsck -p -C0 /dev/mapper/${mapper}
    act "tomb engraved as $tombname"
    tune2fs -L ${tombname} /dev/mapper/${mapper} > /dev/null

    mount -o rw,noatime,nodev /dev/mapper/${mapper} ${tombmount}

    # Ensure the user can write the disk - 10x Hellekin :)
    ME=${SUDO_USER:-$(whoami)}
    chmod 0750 ${tombmount}
    chown $(id -u $ME):$(id -g $ME) ${tombmount}
    
    notice "encrypted storage $tombfile succesfully mounted on $tombmount"
#    exec_bind_hooks ${tombmount}
    if ! [ $NOBIND ]; then
	exec_safe_bind_hooks ${tombmount}
	exec_post_hooks ${tombmount} open
    fi
    return 0
}

encode_key() {
    tombkey=$CMD2
    imagefile=$CMD3

    file $tombkey | grep PGP > /dev/null
    if [ $? != 0 ]; then
        error "encode failed: $tombkey is not a tomb key"
	return 1
    fi
    file $imagefile | grep JPEG > /dev/null
    if [ $? != 0 ]; then
	error "encode failed: $imagefile is not a jpeg image"
	return 1
    fi

    notice "Encoding key $tombkey inside image $imagefile"
    act "please choose a password for the encoding"

    # here user is prompted for key password
    for c in 1 2 3; do
	# 3 tries to write two times a matching password
	tombpass=`exec_as_user tomb askpass ${tombkey}`
	tombpasstmp=$tombpass
	tombpass=`exec_as_user tomb askpass "${tombkey} (again)"`
	if [ "$tombpasstmp" = "$tombpass" ]; then
	    break;
	fi
	unset tombpasstmp
	unset tombpass
    done

    if [ -z $tombpass ]; then
	error "passwords don't match, aborting operation."
	return 1
    fi

    awk '
/^-----/ {next}
/^Version/ {next}
{print $0}' ${tombkey} \
    | steghide embed --embedfile - --coverfile ${imagefile} \
      -p ${tombpass} -z 9 -e serpent cbc
    if [ $? != 0 ]; then
	error "encoding error: steghide reports problems"
	res=1
    else
	notice "tomb key encoded succesfully into image ${imagefile}"
	res=0
    fi

    unset tombpass

    return $res
}

decode_key() {
    tombname=$CMD2
    imagefile=$CMD3
    res=1

    file $imagefile | grep JPEG > /dev/null
    if [ $? != 0 ]; then
	error "encode failed: $imagefile is not a jpeg image"
	return 1
    fi

    keyfile=${tombname%%\.*}.tomb.key
    notice "Trying to exhume a key out of image $imagefile"
    for c in 1 2 3; do
	if [ $c = 1 ]; then
	    tombpass=`exec_as_user tomb askpass ${keyfile}`
	else
	    tombpass=`exec_as_user tomb askpass "$keyfile (retry $c)"`
	fi
	steghide extract -sf ${imagefile} -p ${tombpass} -xf - \
	    | awk '
BEGIN {
print "-----BEGIN PGP MESSAGE-----"
}
{ print $0 }
END {
print "-----END PGP MESSAGE-----"
}' > ${keyfile}
	
	if [ "`cat ${keyfile} | wc -l`" != "3" ]; then
	    act "${keyfile} succesfully decoded"
	    res=0
	    break;
	fi
    done

    unset tombpass

    if [ $res != 0 ]; then
	error "nothing found."
    fi

    return $res
}

exec_bind_hooks() {
    mnt=$1 # first argument is where the tomb is mounted
    if ! [ -r ${mnt}/bind-hooks ]; then return; fi

    # if 'bind-hooks' is found inside the tomb, parse it
    # every line contains two strings:
    # the first is a directory existing inside the tomb
    # the second is the place where it should be mounted (-o bind)
    hook=`cat ${mnt}/bind-hooks | awk '
/^#/ { next }
{ if($1 && $2) print "mount -o bind \${mnt}/" $1 " " $2 "; " }
'`
    # restore $HOME for the calling user
    ME=${SUDO_USER:-$(whoami)}
    HOME=$(grep $ME /etc/passwd | sed "s/^${ME}:.*:.*:.*:.*:\([\/a-z]*\):.*$/\1/" 2>/dev/null)

    act "bind hooks found, mounting directories as requested"
    # execute the mount commands
    eval $hook
}

# FIXME: this should sanitize pathes!
exec_safe_bind_hooks() {
  local MOUNTPOINT="${1}"
  local ME=${SUDO_USER:-$(whoami)}
  local HOME=$(grep $ME /etc/passwd | sed "s/^${ME}:.*:.*:.*:.*:\([\/a-z]*\):.*$/\1/" 2>/dev/null)
  if [ $? -ne 0 ]; then
      error "how pitiful!  A tomb, and no HOME"
      return 1
  fi
  if [ -z "$MOUNTPOINT" -o ! -d "$MOUNTPOINT" ]; then
      error "cannot exec bind hooks without a mounted tomb."
      return 1
   fi
   if ! [ -r "$MOUNTPOINT/bind-hooks" ]; then
      func "bind-hooks not found in $MOUNTPOINT"
      return 1
   fi
   typeset -al mounted
   typeset -Al maps
   maps=($(<"$MOUNTPOINT/bind-hooks"))
   for dir in ${(k)maps}; do
      if [ "${dir[1]}" = "/" -o "${dir[1,2]}" = ".." ]; then
	  error "bind-hooks map format: local/to/tomb local/to/\$HOME"
	  continue
      fi
      if [ "${${maps[$dir]}[1]}" = "/" -o "${${maps[$dir]}[1,2]}" = ".." ]; then
          error "bind-hooks map format: local/to/tomb local/to/\$HOME.  Rolling back"
          for dir in ${mounted}; do umount $dir; done
	  return 1
      fi
      if [ ! -r "$HOME/${maps[$dir]}" ]; then
          error "bind-hook target not existent, skipping $HOME/${maps[$dir]}"
      elif [ ! -r "$MOUNTPOINT/$dir" ]; then
	  error "bind-hook source not found in tomb, skipping ${MOUNTPOINT}/${dir}"
      else
	  mount -o bind $MOUNTPOINT/$dir $HOME/${maps[$dir]}
	  mounted+=("$HOME/${maps[$dir]}")
      fi
   done
}

exec_post_hooks() {
    mnt=$1 # first argument is where the tomb is mounted
    if ! [ -x ${mnt}/post-hooks ]; then return; fi
    # if 'post-hooks' is found inside the tomb, check it: if it is an
    # executable, launch it as a user this might need a dialog for
    # security on what is being run, however we expect you know well
    # what is inside your tomb.  this feature opens the possibility to
    # make encrypted executables.
    cat ${mnt}/post-hooks | head -n1 | grep '^#!/'
    if [ $? = 0 ]; then
	act "post hooks found, executing as user $SUDO_USER"
	exec_as_user ${mnt}/post-hooks $2
    fi
}


backup_tomb() { # FIXME - duplicity asks passwords too often
    # using duplicity
    which duplicity > /dev/null
    if [ $? != 0 ]; then
	error "duplicity not found, can't operate backup"
	return 1
    fi
    if [ -z $CMD3 ]; then
	error "backup command needs 2 arguments: tomb and destination url"
	error "please refer to tomb(1) and duplicity(1) manuals for more information"
	return 1
    fi

    # is it a tomb?
    get_arg_tomb ${CMD2}
    if [ $? != 0 ]; then
	error "there is no tomb to backup, operation aborted."
	return 1
    fi

    # is it a url?
    echo "${CMD3}" | grep -i -e '^.*:\/\/.*' 2>&1 > /dev/null
    if ! [ $? = 0 ]; then
	error "second argument is not a valid duplicity url."
	error "read the tomb(1) and duplicity(1) manual for more information"
	return 1
    fi
    bckurl=${CMD3}

    # is it ssh?
    protocol="`expr substr $bckurl 1 3`"
    act "backup over protocol $protocol"
    if [ "$protocol" = "ssh" ]; then
	act "ssh connection requires a password"
	FTP_PASSWORD="`exec_as_user tomb askpass $bckurl`"
	dupopts="--ssh-askpass"
    # TODO verify ssh access before duplicity does
    #      since it blocks the thing retrying 5 times and such crap
    #      i.e. try ssh true to sshurl="`echo $bckurl | sed -e 's/ssh:\/\///'`"
    #  --no-print-statistics
    fi

    # duplicity works only on directories
    # so we create a directory in tmpfs and bind the tomb inside it
    # during backup the encrypted tomb will be exposed
    # TODO: check that the tomb is not mounted and, if mounted
    #       remount it read-only so it doesn't gets modified during bck
    bckname=${tombname}.bck
    mkdir -p /dev/shm/${bckname}
    if [ $? != 0 ]; then
	error "cannot generate a temporary backup directory in /dev/shm, operation aborted."
	return 1
    fi
    bcktmpdir=/dev/shm/${bckname}
    # mmm, maybe we should mount our own tmpfs? we need root anyway for mount -o bind
    # if we reach to eliminate this mount trick and upload only one file with duplicity
    # then this function doesn't needs to be root to work.
    touch ${bcktmpdir}/${tombfile}
    mount -o bind ${tombdir}/${tombfile} ${bcktmpdir}/${tombfile}
    bcklast=`exec_as_user duplicity \
	${(s: :)dupopts} \
	collection-status ${bckurl} \
	| awk '/^Last full backup date:/ { print $5 }'`
    # we detect if backup already exists or not so we can handle
    # password prompt (choosing a password for full, inserting for incr)
    if [ "$bcklast" = "none" ]; then
	notice "Creating a backup of tomb $tombname on url $bckurl"
	exec_as_user FTP_PASSWORD="$FTP_PASSWORD" duplicity ${(s: :)dupopts} \
	    full ${bcktmpdir} ${bckurl}
    else
	notice "Updating a backup of tomb $tombname on url $bckurl"
	exec_as_user FTP_PASSWORD="$FTP_PASSWORD" duplicity ${(s: :)dupopts} \
	    incr ${bcktmpdir} ${bckurl}
    fi
    unset FTP_PASSWORD
    if [ $? != 0 ]; then
	error "duplicity reported error, operation aborted"
	umount ${bcktmpdir}/${tombfile}
	return 1
    fi
    notice "Operation successful."
    umount ${bcktmpdir}/${tombfile}
    return 0
}

umount_tomb() {

    if ! [ $1 ]; then
	
	how_many_tombs="`find /dev/mapper -name 'tomb.*' | wc -w`"
	if [ "$how_many_tombs" = "0" ]; then
	    error "there is no open tomb to be closed"
	    return 1

	elif [ "$how_many_tombs" = "1" ]; then
	    mapper=`find /dev/mapper -name 'tomb.*'`
	    notice "trying to close $mapper"
	    umount_tomb ${mapper}
	    return 1

	else
	    error "too many tombs mounted, please specify which to unmount:"
	    ls /dev/mapper/tomb.*
	    error "or issue the command 'tomb close all' to clos'em all."
	    return 1
	fi

    fi

    if [ "$1" = "all" ]; then
	tombs=`find /dev/mapper -name 'tomb.*'`
	if ! [ $tombs ]; then
	    notice "Tombs are all closed, cemetery is quiet."
	    return 0
	fi
	for t in ${(f)tombs}; do
	    umount_tomb ${t}
	done
	return 0
    fi

    if ! [ -e "$1" ]; then
	error "tomb not found: $1"
	error "Please specify an existing tomb"
	return 0
    fi

    pathmap=`dirname "$1"`
    if [ "${pathmap}" = "/dev/mapper" ]; then	
	mapper="$1" # $1 is /dev/mapper/tomb.*
        tombname=`basename "$1"` # this is tomb.NAME.XXX.loopX
	tombmount=`mount | grep "$mapper" | awk -F ' ' '{print $3}'` # tomb mount point
    else
        tombmount="$1" # $1 is the tomb mount point (e.g. /mnt)
    	mapper=`mount | grep -w "${tombmount%%/}" | awk -F ' ' '{print $1}'`
	tombname=`basename "$mapper"` # this is tomb.NAME.XXX.loopX
    fi

    # check if there are binded dirs and close them first
    mount | grep "${tombmount%%/}" 2>/dev/null | grep -v loop 2>&1 > /dev/null
    if [ $? = 0 ]; then
	act "closing bind hooks for tomb $tombname "
	unbind=`mount | grep ${tombmount%%/} | grep -v loop | awk '
    { print "umount " $3 "; " }
    '`
	eval $unbind
	func "umount binded dirs:"
	func "$unbind"
    fi

    # Execute post-hooks for eventual cleanup
    if ! [ $NOBIND ]; then
	exec_post_hooks ${tombmount%%/} close
    fi

    act "closing tomb $tombname on dm-crypt $tombmount"
    umount ${tombmount}
    if ! [ $? = 0 ]; then
	    # TODO: ask user if wanting to SLAM the tomb closed
	    # then kill all processes found using it with fuser and lsof
	    return 1
	fi

    cryptsetup luksClose $tombname
    if ! [ $? = 0 ]; then
	error "error occurred in cryptsetup luksClose ${mapper}"
	return 1
    fi

    loopdev=`cut -d '.' -f4 <<< "$tombname"`	
    losetup -d "/dev/$loopdev"

    notice "Tomb $tombname closed: your bones will rest in peace."
    return 0
}

# install mime-types, bells and whistles for the desktop
# see http://developers.sun.com/solaris/articles/integrating_gnome.html
# and freedesktop specs
install_tomb() {

# TODO: distro package deps (for binary)
# debian: zsh, cryptsetup, sudo
    act "updating mimetypes..." 
    cat <<EOF > /tmp/dyne-tomb.xml
<?xml version="1.0"?>
<mime-info xmlns='http://www.freedesktop.org/standards/shared-mime-info'>
  <mime-type type="application/x-tomb-volume">
    <comment>Tomb encrypted volume</comment>
    <glob pattern="*.tomb"/>
  </mime-type>
  <mime-type type="application/x-tomb-key">
    <comment>Tomb crypto key</comment>
    <glob pattern="*.tomb.key"/>
  </mime-type>
</mime-info>
EOF
    xdg-mime install /tmp/dyne-tomb.xml
    xdg-icon-resource install --context mimetypes --size 32 monmort.xpm monmort
    xdg-icon-resource install --size 32 monmort.xpm dyne-monmort
    
    rm /tmp/dyne-tomb.xml
    
    act "updating desktop..."
    cat <<EOF > /usr/share/applications/tomb.desktop
[Desktop Entry]
Version=1.0
Type=Application
Name=Tomb crypto undertaker
GenericName=Crypto undertaker
Comment=Keep your bones safe
Exec=tomb-open %U
TryExec=tomb-open
Icon=monmort.xpm
Terminal=true
Categories=Utility;Security;Archiving;Filesystem;
MimeType=application/x-tomb-volume;
X-AppInstall-Package=tomb
EOF
	update-desktop-database

    act "updating menus..."
    cat <<EOF > /etc/menu/tomb
?package(tomb):command="tomb" icon="/usr/share/pixmaps/monmort.xpm" needs="text" \
	section="Applications/Accessories" title="Tomb" hints="Crypto" \
	hotkey="Tomb"
EOF
    update-menus
    
    act "updating mime info..."
    cat <<EOF > /usr/share/mime-info/tomb.keys
# actions for encrypted tomb storage
application/x-tomb-volume:
	open=tomb-open %f
	view=tomb-open %f
	icon-filename=monmort.xpm
        short_list_application_ids_for_novice_user_level=tomb
EOF
    cat <<EOF > /usr/share/mime-info/tomb.mime
# mime type for encrypted tomb storage
application/x-tomb-volume
	ext: tomb

application/x-tomb-key
        ext: tomb.key
EOF
    cat <<EOF > /usr/lib/mime/packages/tomb
application/x-tomb-volume; tomb-open '%s'; priority=8
EOF
    update-mime

    act "updating application entry..."

    cat <<EOF > /usr/share/application-registry/tomb.applications
tomb
         command=tomb-open
         name=Tomb - Crypto Undertaker
         can_open_multiple_files=false
         expects_uris=false
         requires_terminal=true
         mime-types=application/x-tomb-volume,application/x-tomb-key
EOF
    act "Tomb is now installed."
}

    
	
case "$CMD" in
    create)   check_priv ; create_tomb ;;

    mount)    check_priv ; mount_tomb  ;;
    open)     check_priv ; mount_tomb  ;;

    umount)   check_priv ; umount_tomb ${CMD2} ;;
    unmount)  check_priv ; umount_tomb ${CMD2} ;;
    close)    check_priv ; umount_tomb ${CMD2} ;;

    bury)     encode_key ${CMD2} ${CMD3} ;;
    exhume)   decode_key ${CMD2} ;;

    backup)   check_priv ; backup_tomb ${CMD2} ${CMD3} ;;

    install)  check_priv ; install_tomb ;;

    askpass)  ask_password $CMD2 ;;
    status)   tomb-status ;;

    *) error "command \"$CMD\" not recognized"
	act "try -h for help"
	return 1
	;;
esac
# return codes from called functions
# return $?