[LEDE-DEV] [PATCH] dropbear: automatically add firewall rules based on the config

[Hans Dedecker]

On Wed, Apr 18, 2018 at 12:01 PM, Pierre Lebleu <pme.lebleu at gmail.com> wrote:
> An extra option (AllowedClientIPs:list) is available to allow
> specific clients to use this service.
>
> Testing done:
> root at OpenWrt:~# uci show dropbear
> dropbear.lan=dropbear
> dropbear.lan.enable='1'
> dropbear.lan.Interface='lan'
> dropbear.lan.PasswordAuth='on'
> dropbear.lan.RootPasswordAuth='on'
> dropbear.lan.Port='22'
> dropbear.lan.IdleTimeout='600'
> dropbear.wan=dropbear
> dropbear.wan.Interface='wan'
> dropbear.wan.PasswordAuth='on'
> dropbear.wan.RootPasswordAuth='on'
> dropbear.wan.Port='2223'
> dropbear.wan.IdleTimeout='600'
> dropbear.wan.enable='1'
> dropbear.wan.AllowedClientIPs='1.2.3.4'
> dropbear.wan.RootLogin='0'
>
> root at OpenWrt:~# fw3 print | grep dropbear
> iptables -t filter -A zone_lan_input -p tcp -m tcp --dport 22 -m comment --comment "!fw3: ubus:dropbear[lan] rule 0" -j ACCEPT
> iptables -t filter -A zone_wan_input -p tcp -s 1.2.3.4/255.255.255.255 -m tcp --dport 2223 -m comment --comment "!fw3: ubus:dropbear[wan] rule 0" -j ACCEPT
>
> Signed-off-by: Pierre Lebleu <pme.lebleu at gmail.com>
> ---
>  package/network/services/dropbear/files/dropbear.init  | 47 ++++++++++++++++++++--
>  1 file changed, 44 insertions(+), 3 deletions(-)
>
> diff --git a/package/network/services/dropbear/files/dropbear.init b/package/network/services/dropbear/files/dropbear.init
> index 2225113..2704554 100755
> --- a/package/network/services/dropbear/files/dropbear.init
> +++ b/package/network/services/dropbear/files/dropbear.init
> @@ -43,15 +43,37 @@ validate_section_dropbear()
>                 'IdleTimeout:uinteger:0' \
>                 'MaxAuthTries:uinteger:3' \
>                 'RecvWindowSize:uinteger:0' \
> +               'AllowedClientIPs:list(ipaddr)' \
>                 'mdns:bool:1'
>  }
>
> +add_fw_rules()
> +{
> +       local intf="$1"
> +       local port="$2"
> +       local client="$3"
> +
> +       [ -z "${intf}" ] && return
> +       local zone=$(fw3 -q network "${intf}")
> +       [ -z "${zone}" ] && return
> +
> +       json_add_object ""
> +       json_add_string type rule
> +       json_add_string src "${zone}"
> +       json_add_string proto tcp
> +       json_add_string dest_port "${port}"
> +       [ -n "${client}" ] && json_add_string src_ip "${client}"
> +       json_add_string target ACCEPT
> +       json_close_object
> +}
> +
>  dropbear_instance()
>  {
>         local PasswordAuth enable Interface GatewayPorts \
>                 RootPasswordAuth RootLogin rsakeyfile \
>                 BannerFile Port SSHKeepAlive IdleTimeout \
> -               MaxAuthTries RecvWindowSize mdns ipaddrs
> +               MaxAuthTries RecvWindowSize AllowedClientIPs \
> +               mdns ipaddrs
>
>         validate_section_dropbear "${1}" || {
>                 echo "validation failed"
> @@ -69,7 +91,8 @@ dropbear_instance()
>         PIDCOUNT="$(( ${PIDCOUNT} + 1))"
>         local pid_file="/var/run/${NAME}.${PIDCOUNT}.pid"
>
> -       procd_open_instance
> +       procd_open_instance "${1}"
> +
>         procd_set_param command "$PROG" -F -P "$pid_file"
>         [ "${PasswordAuth}" -eq 0 ] && procd_append_param command -s
>         [ "${GatewayPorts}" -eq 1 ] && procd_append_param command -a
> @@ -83,8 +106,22 @@ dropbear_instance()
>         [ "${MaxAuthTries}" -ne 0 ] && procd_append_param command -T "${MaxAuthTries}"
>         [ "${RecvWindowSize}" -gt 0 -a "${RecvWindowSize}" -le 1048576 ] && \
>                 procd_append_param command -W "${RecvWindowSize}"
> -       [ "${mdns}" -ne 0 ] && procd_add_mdns "ssh" "tcp" "$Port" "daemon=dropbear"
>         procd_set_param respawn
> +
> +       procd_open_data
> +
> +       [ "${mdns}" -ne 0 ] && {
> +               json_add_object "mdns"
> +               procd_add_mdns_service "ssh" "tcp" "$Port" "daemon=dropbear"
> +               json_close_object
> +       }
> +
> +       json_add_array firewall
> +       add_fw_rules "${Interface}" "${Port}" "${AllowedClientIPs}"
> +       json_close_array
This will create an empty firewall procd data entry if either there's
no interface or the interface does not belong to a firewall zone which
is suboptimal

Hans
> +
> +       procd_close_data
> +
>         procd_close_instance
>  }
>
> @@ -130,6 +167,10 @@ start_service()
>         config_foreach dropbear_instance dropbear
>  }
>
> +service_started() {
> +       procd_set_config_changed firewall
> +}
> +
>  service_triggers()
>  {
>         local interfaces
> --
> 1.9.1
>
>
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