openwrt/package/network/services/dropbear/files/dropbear.init
Konstantin Demin 3f96246e97 dropbear: better handle interfaces
- introduce 'DirectInterface' option to bind exactly to specified interface;
  fixes #9666 and late IPv4/IPv6 address assignment
- option 'DirectInterface' takes precedence over 'Interface'
- improve interface/address handling,
  e.g. verify count of listening endpoints due to dropbear limit (10 for now)

Signed-off-by: Konstantin Demin <rockdrilla@gmail.com>
2024-02-09 09:13:05 +00:00

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#!/bin/sh /etc/rc.common
# Copyright (C) 2006-2010 OpenWrt.org
# Copyright (C) 2006 Carlos Sobrinho
START=19
STOP=50
USE_PROCD=1
PROG=/usr/sbin/dropbear
NAME=dropbear
PIDCOUNT=0
extra_command "killclients" "Kill ${NAME} processes except servers and yourself"
# most of time real_stat() will be failing
# due to missing "stat" binary (by default)
real_stat() { env stat -L "$@" 2>/dev/null ; }
dumb_stat() { ls -Ldln "$1" | tr -s '\t ' ' ' ; }
stat_perm() { real_stat -c '%A' "$1" || dumb_stat "$1" | cut -d ' ' -f 1 ; }
stat_owner() { real_stat -c '%u' "$1" || dumb_stat "$1" | cut -d ' ' -f 3 ; }
_dropbearkey()
{
/usr/bin/dropbearkey "$@" </dev/null >/dev/null 2>&1
}
# $1 - file name (host key or config)
file_verify()
{
[ -f "$1" ] || return 1
# checking file ownership
[ "$(stat_owner "$1")" = "0" ] || {
chown 0 "$1"
[ "$(stat_owner "$1")" = "0" ] || return 2
}
# checking file permissions
[ "$(stat_perm "$1")" = "-rw-------" ] || {
chmod 0600 "$1"
[ "$(stat_perm "$1")" = "-rw-------" ] || return 3
}
# file is host key or not?
# if $2 is empty string - file is "host key"
# if $2 is non-empty string - file is "config"
[ -z "$2" ] || return 0
# checking file contents (finally)
[ -s "$1" ] || return 4
_dropbearkey -y -f "$1" || return 5
return 0
}
# $1 - file_verify() return code
file_errmsg()
{
case "$1" in
0) ;;
1) echo "file does not exist" ;;
2) echo "file has wrong owner (must be owned by root)" ;;
3) echo "file has wrong permissions (must not have group/other write bit)" ;;
4) echo "file has zero length" ;;
5) echo "file is not valid host key or not supported" ;;
*) echo "unknown error" ;;
esac
}
# $1 - config option
# $2 - host key file name
hk_config()
{
local x m
file_verify "$2" ; x=$?
if [ "$x" = 0 ] ; then
procd_append_param command -r "$2"
return
fi
m=$(file_errmsg "$x")
logger -s -t "${NAME}" -p daemon.warn \
"Option '$1', skipping '$2': $m"
}
# $1 - host key file name
hk_config__keyfile() { hk_config keyfile "$1" ; }
ktype_all='ed25519 ecdsa rsa'
hk_generate_as_needed()
{
local hk_cfg_dir kgen ktype kfile hk_tmp_dir
hk_cfg_dir='/etc/dropbear'
[ -d "${hk_cfg_dir}" ] || mkdir -p "${hk_cfg_dir}"
kgen=
for ktype in ${ktype_all} ; do
kfile="${hk_cfg_dir}/dropbear_${ktype}_host_key"
if file_verify "${kfile}" ; then continue ; fi
kgen="${kgen}${kgen:+ }${ktype}"
done
# all keys are sane?
[ -n "${kgen}" ] || return 0
hk_tmp_dir=$(mktemp -d)
# system in bad state?
[ -n "${hk_tmp_dir}" ] || return 1
chmod 0700 "${hk_tmp_dir}"
for ktype in ${kgen} ; do
kfile="${hk_tmp_dir}/dropbear_${ktype}_host_key"
if ! _dropbearkey -t ${ktype} -f "${kfile}" ; then
# unsupported key type
rm -f "${kfile}"
continue
fi
chmod 0600 "${kfile}"
done
kgen=
for ktype in ${ktype_all} ; do
kfile="${hk_tmp_dir}/dropbear_${ktype}_host_key"
[ -s "${kfile}" ] || continue
kgen="${kgen}${kgen:+ }${ktype}"
done
if [ -n "${kgen}" ] ; then
for ktype in ${kgen} ; do
kfile="${hk_tmp_dir}/dropbear_${ktype}_host_key"
[ -s "${kfile}" ] || continue
mv -f "${kfile}" "${hk_cfg_dir}/"
done
fi
rm -rf "${hk_tmp_dir}"
# cleanup empty files
for ktype in ${ktype_all} ; do
kfile="${hk_cfg_dir}/dropbear_${ktype}_host_key"
[ -s "${kfile}" ] || rm -f "${kfile}"
done
}
# $1 - list with whitespace-separated elements
normalize_list()
{
printf '%s' "$1" | tr -s ' \r\n\t' ' ' | sed -E 's/^ //;s/ $//'
}
warn_multiple_interfaces()
{
logger -t "${NAME}" -p daemon.warn \
"Option '$1' should specify SINGLE interface but instead it lists interfaces: $2"
logger -t "${NAME}" -p daemon.warn \
"Consider creating per-interface instances instead!"
}
validate_section_dropbear()
{
uci_load_validate dropbear dropbear "$1" "$2" \
'PasswordAuth:bool:1' \
'enable:bool:1' \
'DirectInterface:string' \
'Interface:string' \
'GatewayPorts:bool:0' \
'ForceCommand:string' \
'RootPasswordAuth:bool:1' \
'RootLogin:bool:1' \
'rsakeyfile:file' \
'keyfile:list(file)' \
'BannerFile:file' \
'Port:port:22' \
'SSHKeepAlive:uinteger:300' \
'IdleTimeout:uinteger:0' \
'MaxAuthTries:uinteger:3' \
'RecvWindowSize:uinteger:262144' \
'mdns:bool:1'
}
dropbear_instance()
{
[ "$2" = 0 ] || {
echo "validation failed"
return 1
}
[ "${enable}" = "1" ] || return 1
local iface ndev ipaddrs
# 'DirectInterface' should specify single interface
# but end users may misinterpret this setting
DirectInterface=$(normalize_list "${DirectInterface}")
# 'Interface' should specify single interface
# but end users are often misinterpret this setting
Interface=$(normalize_list "${Interface}")
if [ -n "${Interface}" ] ; then
if [ -n "${DirectInterface}" ] ; then
logger -t "${NAME}" -p daemon.warn \
"Option 'DirectInterface' takes precedence over 'Interface'"
else
logger -t "${NAME}" -p daemon.info \
"Option 'Interface' binds to address(es) but not to interface"
logger -t "${NAME}" -p daemon.info \
"Consider using option 'DirectInterface' to bind directly to interface"
fi
fi
# handle 'DirectInterface'
iface=$(echo "${DirectInterface}" | awk '{print $1}')
case "${DirectInterface}" in
*\ *)
warn_multiple_interfaces DirectInterface "${DirectInterface}"
logger -t "${NAME}" -p daemon.warn \
"Using network interface '${iface}' for direct binding"
;;
esac
while [ -n "${iface}" ] ; do
# if network is available (even during boot) - proceed
if network_is_up "${iface}" ; then break ; fi
# skip during boot
[ -z "${BOOT}" ] || return 0
logger -t "${NAME}" -p daemon.crit \
"Network interface '${iface}' is not available!"
return 1
done
while [ -n "${iface}" ] ; do
# ${iface} is logical (higher level) interface name
# ${ndev} is 'real' interface name
# e.g.: if ${iface} is 'lan' (default LAN interface) then ${ndev} is 'br-lan'
network_get_device ndev "${iface}"
[ -z "${ndev}" ] || break
logger -t "${NAME}" -p daemon.crit \
"Missing network device for network interface '${iface}'!"
return 1
done
if [ -n "${iface}" ] ; then
logger -t "${NAME}" -p daemon.info \
"Using network interface '${iface}' (network device '${ndev}') for direct binding"
fi
# handle 'Interface'
while [ -z "${iface}" ] ; do
[ -n "${Interface}" ] || break
# skip during boot
[ -z "${BOOT}" ] || return 0
case "${Interface}" in
*\ *)
warn_multiple_interfaces Interface "${Interface}"
;;
esac
local c=0
# sysoptions.h
local DROPBEAR_MAX_PORTS=10
local a n if_ipaddrs
for n in ${Interface} ; do
[ -n "$n" ] || continue
if_ipaddrs=
network_get_ipaddrs_all if_ipaddrs "$n"
[ -n "${if_ipaddrs}" ] || {
logger -s -t "${NAME}" -p daemon.err \
"Network interface '$n' has no suitable IP address(es)!"
continue
}
[ $c -le ${DROPBEAR_MAX_PORTS} ] || {
logger -s -t "${NAME}" -p daemon.err \
"Network interface '$n' is NOT listened due to option limit exceed!"
continue
}
for a in ${if_ipaddrs} ; do
[ -n "$a" ] || continue
c=$((c+1))
if [ $c -le ${DROPBEAR_MAX_PORTS} ] ; then
ipaddrs="${ipaddrs} $a"
continue
fi
logger -t "${NAME}" -p daemon.err \
"Endpoint '$a:${Port}' on network interface '$n' is NOT listened due to option limit exceed!"
done
done
break
done
PIDCOUNT="$(( ${PIDCOUNT} + 1))"
local pid_file="/var/run/${NAME}.${PIDCOUNT}.pid"
procd_open_instance
procd_set_param command "$PROG" -F -P "$pid_file"
if [ -n "${iface}" ] ; then
# if ${iface} is non-empty then ${ndev} is non-empty too
procd_append_param command -l "${ndev}" -p "${Port}"
else
if [ -z "${ipaddrs}" ] ; then
procd_append_param command -p "${Port}"
else
local a
for a in ${ipaddrs} ; do
[ -n "$a" ] || continue
procd_append_param command -p "$a:${Port}"
done
fi
fi
[ "${PasswordAuth}" -eq 0 ] && procd_append_param command -s
[ "${GatewayPorts}" -eq 1 ] && procd_append_param command -a
[ -n "${ForceCommand}" ] && procd_append_param command -c "${ForceCommand}"
[ "${RootPasswordAuth}" -eq 0 ] && procd_append_param command -g
[ "${RootLogin}" -eq 0 ] && procd_append_param command -w
config_list_foreach "$1" 'keyfile' hk_config__keyfile
if [ -n "${rsakeyfile}" ]; then
logger -s -t "${NAME}" -p daemon.crit \
"Option 'rsakeyfile' is considered to be DEPRECATED and will be REMOVED in future releases, use 'keyfile' list instead"
sed -i.before-upgrade -E -e 's/option(\s+)rsakeyfile/list keyfile/' \
"/etc/config/${NAME}"
logger -s -t "${NAME}" -p daemon.crit \
"Auto-transition 'option rsakeyfile' => 'list keyfile' in /etc/config/${NAME} is done, please verify your configuration"
hk_config 'rsakeyfile' "${rsakeyfile}"
fi
[ -n "${BannerFile}" ] && procd_append_param command -b "${BannerFile}"
[ "${IdleTimeout}" -ne 0 ] && procd_append_param command -I "${IdleTimeout}"
[ "${SSHKeepAlive}" -ne 0 ] && procd_append_param command -K "${SSHKeepAlive}"
[ "${MaxAuthTries}" -ne 0 ] && procd_append_param command -T "${MaxAuthTries}"
[ "${RecvWindowSize}" -gt 0 ] && {
# NB: OpenWrt increases receive window size to increase throughput on high latency links
# ref: validate_section_dropbear()
# default receive window size is 24576 (DEFAULT_RECV_WINDOW in default_options.h)
# sysoptions.h
local MAX_RECV_WINDOW=10485760
if [ "${RecvWindowSize}" -gt ${MAX_RECV_WINDOW} ] ; then
# separate logging is required because syslog misses dropbear's message
# Bad recv window '${RecvWindowSize}', using ${MAX_RECV_WINDOW}
# it's probably dropbear issue but we should handle this and notify user
logger -s -t "${NAME}" -p daemon.warn \
"Option 'RecvWindowSize' is too high (${RecvWindowSize}), limiting to ${MAX_RECV_WINDOW}"
RecvWindowSize=${MAX_RECV_WINDOW}
fi
procd_append_param command -W "${RecvWindowSize}"
}
[ "${mdns}" -ne 0 ] && procd_add_mdns "ssh" "tcp" "$Port" "daemon=dropbear"
procd_set_param respawn
procd_close_instance
}
load_interfaces()
{
local enable
config_get enable "$1" enable 1
[ "${enable}" = "1" ] || return 0
local direct_iface iface
config_get direct_iface "$1" DirectInterface
direct_iface=$(normalize_list "${direct_iface}")
# 'DirectInterface' takes precedence over 'Interface'
if [ -n "${direct_iface}" ] ; then
iface=$(echo "${direct_iface}" | awk '{print $1}')
else
config_get iface "$1" Interface
iface=$(normalize_list "${iface}")
fi
interfaces="${interfaces} ${iface}"
}
boot()
{
BOOT=1
start "$@"
}
start_service()
{
hk_generate_as_needed
file_verify /etc/dropbear/authorized_keys config
. /lib/functions.sh
. /lib/functions/network.sh
config_load "${NAME}"
config_foreach validate_section_dropbear dropbear dropbear_instance
}
service_triggers()
{
local interfaces
procd_add_config_trigger "config.change" "${NAME}" /etc/init.d/dropbear reload
config_load "${NAME}"
config_foreach load_interfaces "${NAME}"
[ -n "${interfaces}" ] && {
local n
for n in $(printf '%s\n' ${interfaces} | sort -u) ; do
procd_add_interface_trigger "interface.*" $n /etc/init.d/dropbear reload
done
}
procd_add_validation validate_section_dropbear
}
shutdown() {
# close all open connections
killall dropbear
}
killclients()
{
local ignore=''
local server
local pid
# if this script is run from inside a client session, then ignore that session
pid="$$"
while [ "${pid}" -ne 0 ]
do
# get parent process id
pid=$(cut -d ' ' -f 4 "/proc/${pid}/stat")
[ "${pid}" -eq 0 ] && break
# check if client connection
grep -F -q -e "${PROG}" "/proc/${pid}/cmdline" && {
append ignore "${pid}"
break
}
done
# get all server pids that should be ignored
for server in $(cat /var/run/${NAME}.*.pid)
do
append ignore "${server}"
done
# get all running pids and kill client connections
local skip
for pid in $(pidof "${NAME}")
do
# check if correct program, otherwise process next pid
grep -F -q -e "${PROG}" "/proc/${pid}/cmdline" || {
continue
}
# check if pid should be ignored (servers, ourself)
skip=0
for server in ${ignore}
do
if [ "${pid}" = "${server}" ]
then
skip=1
break
fi
done
[ "${skip}" -ne 0 ] && continue
# kill process
echo "${initscript}: Killing ${pid}..."
kill -KILL ${pid}
done
}