#!/usr/bin/env bash
# Author: samba
# Date: 2018-02-19
# Desc: unlock the root partition via initrd

PRIVATE_KEY=$HOME/.ssh/id_ed25519
KNOWN_HOSTS_FILE=$HOME/.ssh/boot/known_hosts
KNOWN_HOSTS_TMPFILE=/tmp/unlockboot.known_hosts
LOGFILE=/tmp/unlockboot.log
SSHKEY=0
DEBUG=0
trap ctrl_c INT
usage() {
    cat <<EOF
Unlock an encrypted root disk remotely.

Usage: $0

    -a|--address    Specify the ipaddress of the host to unlock (required)
    -p|--password   Specify the password to unlock the encrypted disk (required)
    -i|--idssh)     Specify the ssh private key file (default: $PRIVATE_KEY)
    -s|--sshkey     Connect via ssh and print the ssh fingerprint (useful to add new trusted hosts)
    -k|--known-host Specify the known_hosts file to use when connecting to (default: $KNOWN_HOSTS_FILE)
    -d|--debug)     Print debug information 
    -h|--help)      Print this help and exit

Example:
    $0 -a 192.168.97.2 -p \$(pass sys/vm/MYSERVERNAME/luks)
    $0 -a 192.168.97.2 -i $HOME/.ssh/id_rsa -p \$(pass sys/vm/MYSERVERNAME/luks)
    $0 -a 192.168.97.2 -i $HOME/.ssh/id_rsa -p \$(pass sys/vm/MYSERVERNAME/luks) -i $HOME/.ssh/id_rsa
EOF
    exit 2
}
info(){
    TIMESTAMP=$(date '+%F %T')
    echo "$TIMESTAMP - INFO: $*" | tee -a $LOGFILE
}
warning(){
    TIMESTAMP=$(date '+%F %T')
    echo "$TIMESTAMP - WARNING: $*" | tee -a $LOGFILE
}
debug(){
    [ $DEBUG -ne 1 ] && return
    TIMESTAMP=$(date '+%F %T')
    echo "$TIMESTAMP - DEBUG:  $*" | tee -a $LOGFILE
}
error(){
    TIMESTAMP=$(date '+%F %T')
    echo "$TIMESTAMP - ERROR: $*" | tee -a $LOGFILE
    exit 1
}
ctrl_c(){
    error "Force exit"
}

wait_host_up(){
    # Wait until the host is up.
    TIMEOUT=300 #seconds = 5m
    debug "Waiting for the host to back online, TIMEOUT: $TIMEOUT sec"
    COUNT=0
    echo " [*] waiting ${TIMEOUT}s for the host respond to ping"
    while true ; do
      ping -n -w 1 -q -c1 "$IP" >/dev/null 2>&1 && break
      [ $[$TIMEOUT % 60] -eq 0 ] && echo -en "\n [*] " || echo -n "."
      TIMEOUT=$[$TIMEOUT-1]
      [ $TIMEOUT -eq 0 ] && echo -e "\n" && error "host $IP reach timeout ${TIMEOUT}s" && exit 1
    done
    echo -e "\n [*] host is alive"
}

ssh_getsshkey(){
    info "Getting ssh key fingerprint"
    info "WARNING: the use of this tool works ONLY when is running dropbear-initramfs"

    OUT=$(ssh-keyscan -t ecdsa-sha2-nistp521 $IP)
    info "Host ssh key:"
    echo
    echo "----------- SSH-KEY ---------"
    echo "$OUT"
    echo "----------- *** *** *** ---------"
    echo 
    echo "To add a TRUSTED HOST you can copy the SSH-KEY and paste it into the script \"$0\" "
    exit 0
    }

# Add here your SSH pubkey (use -s option)
cat <<EOF > $KNOWN_HOSTS_TMPFILE
antifa.tech ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBDUB3sQqMpiuu+5vgsOia4iyOHA30UguQe2HdkWnbmfH0fFx5HbXkHWT5z5N4j8mcblt+WCAyDihl7gGl54X0UE=
EOF



[ $# -eq 0 ] && usage

while [ $# -ne 0 ];do
    debug "ARGS: $*"
    case ${1} in
        -a|--address)
            shift
            IP=$1
            ;;
        -i|--idssh)
            shift
            PRIVATE_KEY=$1
            ;;
        -k|--known-hosts)
            shift
            KNOWN_HOSTS_FILE=$1
            ;;
        -p|--pass)
            shift
            PASSWORD=$(echo $1| head -n1)
            ;;
        -d|--debug)
            DEBUG=1
            ;;
        -s|--sshkey)
            SSHKEY=1
            ;;
        *)
            usage 
            ;;
        esac
        shift
done

# check IP
[ "$IP" == "" ] && error "IP Address not provided (required)"

[ "$SSHKEY" -eq 1 ] && ssh_getsshkey

# check priv key
[ ! -e $PRIVATE_KEY ] && error "ssh private key not found in $PRIVATE_KEY"
[ $(grep -c 'PRIVATE KEY' $PRIVATE_KEY) -eq 0 ] && error "unable to find SSH private key at $PRIVATE_KEY"

# check password is valid
if [ "$PASSWORD" == "" ];then
    error "No password provided  (password is required)
    you did not provide a password provided to unlock the LUKS disk
    Please check usage (--help)"
fi

HASHNEW=$(sha1sum $KNOWN_HOSTS_TMPFILE | cut -f 1 -d ' ')
HASHOLD=$(sha1sum $KNOWN_HOSTS_FILE | cut -f 1 -d ' ')

# See if we have a dropbear_known_hosts file.
if [ "$HASHNEW" != "$HASHOLD" ]; then
    debug "file differs ${KNOWN_HOSTS_FILE} $KNOWN_HOSTS_TMPFILE"
    info "The file ${KNOWN_HOSTS_FILE} has been automatically updated"
    #to ensure no-one will steal the LUKS passphrase we need to connect to known_hosts ONLY
    [ ! -e $(dirname $KNOWN_HOSTS_FILE) ] && mkdir -p $(dirname $KNOWN_HOSTS_FILE)
    debug "copyting $KNOWN_HOSTS_TMPFILE into $KNOWN_HOSTS_FILE"
    cp $KNOWN_HOSTS_TMPFILE  $KNOWN_HOSTS_FILE
    debug "clean $KNOWN_HOSTS_TMPFILE"
    rm $KNOWN_HOSTS_TMPFILE
fi


wait_host_up

# unlock boot using PASSWORD

echo " [*] unlocking the boot"
ssh \
    -4 \
    -o BatchMode=yes \
    -o MACs=hmac-sha1 \
    -o UserKnownHostsFile=/dev/null \
    -o GlobalKnownHostsFile=$KNOWN_HOSTS_FILE \
    -o VerifyHostKeyDNS=no \
    -i $PRIVATE_KEY \
    -F /dev/null \
    root@$IP \
    "echo -n '$PASSWORD' > /lib/cryptsetup/passfifo" 2>&1 >/dev/null
if [ $? -gt 0 ]; then
    error "FAILED to unlock, reason: HOST UNKNOWN"
fi

debug "Host unlocked"
echo " [*] Boot unlock successful, waiting for the machine to complete the boot"
sleep 10s 
wait_host_up
debug "host unlocked back online"
echo " [!] Host started successfully! You can now try to connect via ssh to $IP"

exit 0