Add genkernel worker module "dropbear"

This commit will add support for "dropbear"-related tasks.

Signed-off-by: Thomas Deutschmann <whissi@gentoo.org>

2 files changed, 164 insertions, 0 deletions

diff --git a/gen_worker.sh b/gen_worker.sh
index 1c01561..8b59f1a 100755
--- a/gen_worker.sh
+++ b/gen_worker.sh
@@ -140,6 +140,9 @@ case "${1}" in
 	build)
 		MODULE="${GK_SHARE}/worker_modules/gkbuild.sh"
 		;;
+	dropbear)
+		MODULE="${GK_SHARE}/worker_modules/dropbear.sh"
+		;;
 	unpack)
 		MODULE="${GK_SHARE}/worker_modules/unpack.sh"
 		;;
diff --git a/worker_modules/dropbear.sh b/worker_modules/dropbear.sh
new file mode 100644
index 0000000..3d8c4fa
--- /dev/null
+++ b/worker_modules/dropbear.sh
@@ -0,0 +1,161 @@
+#!/bin/bash
+# Copyright 1999-2019 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+__module_main() {
+	if [[ -z "${DROPBEAR_COMMAND}" ]]
+	then
+		die "Do not know which dropbear command should run: DROPBEAR_COMMAND not set!"
+	elif [[ -z "${DROPBEAR_KEY_FILE}" ]]
+	then
+		die "Unable to create new dropbear host key: DROPBEAR_KEY_FILE not set!"
+	elif [[ -z "${DROPBEAR_KEY_TYPE}" ]]
+	then
+		die "Unable to create new dropbear host key: DROPBEAR_KEY_TYPE not set!"
+	elif [[ -z "${TEMP}" ]]
+	then
+		die "Unable to do work: TEMP is not set!"
+	fi
+
+	local real_main_function=
+	case "${DROPBEAR_COMMAND}" in
+		*dropbearconvert)
+			if [[ -n "${DROPBEAR_KEY_INFO_FILE}" ]]
+			then
+				real_main_function=_dropbear_create_key_info_file
+			else
+				real_main_function=_dropbear_create_from_host
+			fi
+			;;
+		*dropbearkey)
+			real_main_function=_dropbear_create_new
+			;;
+		*)
+			die "Unknown DROPBEAR_COMMAND '${DROPBEAR_COMMAND}' set!"
+			;;
+	esac
+
+	local dropbear_temp=$(mktemp -d -p "${TEMP}" dropbear.XXXXXXXX 2>/dev/null)
+	[ -z "${dropbear_temp}" ] && die "mktemp failed!"
+
+	cd "${dropbear_temp}" || die "Failed to chdir to '${dropbear_temp}'!"
+
+	addwrite "/dev/random:/dev/urandom"
+
+	${real_main_function}
+}
+
+_dropbear_create_from_host() {
+	local keyname="dropbear_${DROPBEAR_KEY_TYPE}.key"
+
+	local ssh_host_key=/etc/ssh/
+	case "${DROPBEAR_KEY_TYPE}" in
+		dss)
+			ssh_host_key+=ssh_host_dsa_key
+			;;
+		ecdsa)
+			ssh_host_key+=ssh_host_ecdsa_key
+			;;
+		ed25519)
+			ssh_host_key+=ssh_host_ed25519_key
+			;;
+		rsa)
+			ssh_host_key+=ssh_host_rsa_key
+			;;
+		*)
+			die "Dropbear key type '${DROPBEAR_KEY_TYPE}' is unknown!"
+			;;
+	esac
+
+	local ssh_host_keyname=$(basename "${ssh_host_key}")
+	if [ -z "${ssh_host_keyname}" ]
+	then
+		die "Failed to get basename from '${ssh_host_key}'!"
+	fi
+
+	cp -aL "${ssh_host_key}" . || die "Failed to copy '${ssh_host_key}' to '$(pwd)'!"
+
+	# Dropbear doesn't support RFC4716 format yet -- luckily ssh-keygen
+	# can be used to convert existing key ...
+	local command=( "ssh-keygen -p -P '' -N '' -m PEM -f ${ssh_host_keyname} &>/dev/null" )
+	gkexec "${command[*]}"
+
+	# Now we can convert using dropbearconvert ...
+	command=( "${DROPBEAR_COMMAND} openssh dropbear ${ssh_host_keyname} ${keyname} &>/dev/null" )
+	gkexec "${command[*]}"
+
+	_dropbear_install "${keyname}"
+}
+
+_dropbear_create_key_info_file() {
+	local ssh_key_file=
+	case "${DROPBEAR_KEY_TYPE}" in
+		dss)
+			ssh_key_file=ssh_host_dsa_key
+			;;
+		ecdsa)
+			ssh_key_file=ssh_host_ecdsa_key
+			;;
+		ed25519)
+			ssh_key_file=ssh_host_ed25519_key
+			;;
+		rsa)
+			ssh_key_file=ssh_host_rsa_key
+			;;
+		*)
+			die "Dropbear key type '${DROPBEAR_KEY_TYPE}' is unknown!"
+			;;
+	esac
+
+	local ssh_key_info_file="${ssh_key_file}.info"
+
+	# Convert to SSH key format because dropbear only supports its own SHA1 implementation ...
+	local command=( "${DROPBEAR_COMMAND} dropbear openssh ${DROPBEAR_KEY_FILE} ${ssh_key_file}" )
+	gkexec "${command[*]}"
+
+	# MD5
+	ssh-keygen -l -E md5 -f ${ssh_key_file} > ${ssh_key_info_file} 2>/dev/null \
+		|| die "Failed to extract MD5 fingerprint from SSH key '${ssh_key_file}'!"
+
+	# SHA256
+	ssh-keygen -l -E sha256 -f ${ssh_key_file} >> ${ssh_key_info_file} 2>/dev/null \
+		|| die "Failed to extract MD5 fingerprint from SSH key '${ssh_key_file}'!"
+
+	sed -i \
+		-e 's/no comment //' \
+		"${ssh_key_info_file}" \
+		|| die "Failed to remove comment from '${ssh_key_info_file}'!"
+
+	DROPBEAR_KEY_FILE=${DROPBEAR_KEY_INFO_FILE}
+	_dropbear_install "${ssh_key_info_file}"
+}
+
+_dropbear_create_new() {
+	local keyname="dropbear_${DROPBEAR_KEY_TYPE}.key"
+
+	local command=( "${DROPBEAR_COMMAND} -t ${DROPBEAR_KEY_TYPE} -f ${keyname} &>/dev/null" )
+	gkexec "${command[*]}"
+
+	_dropbear_install "${keyname}"
+}
+
+_dropbear_install() {
+	local keyfile=${1}
+	if [[ -z "${keyfile}" || ! -f "${keyfile}" ]]
+	then
+		die "$(get_useful_function_stack "${FUNCNAME}")Invalid usage of ${FUNCNAME}(): Keyfile '${keyfile}' is invalid!"
+	fi
+
+	local key_destdir=$(dirname "${DROPBEAR_KEY_FILE}")
+	addwrite "${key_destdir}"
+
+	if [[ ! -d "${key_destdir}" ]]
+	then
+		mkdir -p "${key_destdir}" || die "Failed to create '${key_destdir}'!"
+	fi
+
+	cp -a "${keyfile}" "${DROPBEAR_KEY_FILE}" || die "Failed copy '${keyfile}' to '${DROPBEAR_KEY_FILE}'!"
+
+	# end here -- sandbox is open!
+	exit 0
+}