qubes-mirage-firewall/dao.ml
2020-05-15 16:25:46 +02:00

148 lines
5.2 KiB
OCaml

(* Copyright (C) 2015, Thomas Leonard <thomas.leonard@unikernel.com>
See the README file for details. *)
open Lwt.Infix
open Qubes
open Astring
let src = Logs.Src.create "dao" ~doc:"QubesDB data access"
module Log = (val Logs.src_log src : Logs.LOG)
module ClientVif = struct
type t = {
domid : int;
device_id : int;
}
let pp f { domid; device_id } = Fmt.pf f "{domid=%d;device_id=%d}" domid device_id
let compare = compare
end
module VifMap = struct
include Map.Make(ClientVif)
let rec of_list = function
| [] -> empty
| (k, v) :: rest -> add k v (of_list rest)
let find key t =
try Some (find key t)
with Not_found -> None
end
let directory ~handle dir =
OS.Xs.directory handle dir >|= function
| [""] -> [] (* XenStore client bug *)
| items -> items
let db_root client_ip =
"/qubes-firewall/" ^ (Ipaddr.V4.to_string client_ip)
let read_rules rules client_ip =
let root = db_root client_ip in
let rec get_rule n l : (Pf_qubes.Parse_qubes.rule list, string) result =
let pattern = root ^ "/" ^ Printf.sprintf "%04d" n in
Log.debug (fun f -> f "reading %s" pattern);
match Qubes.DB.KeyMap.find_opt pattern rules with
| None ->
Log.debug (fun f -> f "rule %d does not exist; won't look for more" n);
Ok (List.rev l)
| Some rule ->
Log.debug (fun f -> f "rule %d: %s" n rule);
match Pf_qubes.Parse_qubes.parse_qubes ~number:n rule with
| Error e -> Log.warn (fun f -> f "Error parsing rule %d: %s" n e); Error e
| Ok rule ->
Log.debug (fun f -> f "parsed rule: %a" Pf_qubes.Parse_qubes.pp_rule rule);
get_rule (n+1) (rule :: l)
in
match get_rule 0 [] with
| Ok l -> l
| Error e ->
Log.warn (fun f -> f "Defaulting to deny-all because of rule parse failure (%s)" e);
[ Pf_qubes.Parse_qubes.({action = Drop;
proto = None;
specialtarget = None;
dst = `any;
dstports = None;
icmp_type = None;
number = 0;})]
let vifs ~handle domid =
match String.to_int domid with
| None -> Log.err (fun f -> f "Invalid domid %S" domid); Lwt.return []
| Some domid ->
let path = Printf.sprintf "backend/vif/%d" domid in
directory ~handle path >>=
Lwt_list.filter_map_p (fun device_id ->
match String.to_int device_id with
| None -> Log.err (fun f -> f "Invalid device ID %S for domid %d" device_id domid); Lwt.return_none
| Some device_id ->
let vif = { ClientVif.domid; device_id } in
Lwt.try_bind
(fun () -> OS.Xs.read handle (Printf.sprintf "%s/%d/ip" path device_id))
(fun client_ip ->
let client_ip = Ipaddr.V4.of_string_exn client_ip in
Lwt.return (Some (vif, client_ip))
)
(function
| Xs_protocol.Enoent _ -> Lwt.return None
| ex ->
Log.err (fun f -> f "Error getting IP address of %a: %s"
ClientVif.pp vif (Printexc.to_string ex));
Lwt.return None
)
)
let watch_clients fn =
OS.Xs.make () >>= fun xs ->
let backend_vifs = "backend/vif" in
Log.info (fun f -> f "Watching %s" backend_vifs);
OS.Xs.wait xs (fun handle ->
begin Lwt.catch
(fun () -> directory ~handle backend_vifs)
(function
| Xs_protocol.Enoent _ -> Lwt.return []
| ex -> Lwt.fail ex)
end >>= fun items ->
Lwt_list.map_p (vifs ~handle) items >>= fun items ->
fn (List.concat items |> VifMap.of_list);
(* Wait for further updates *)
Lwt.fail Xs_protocol.Eagain
)
type network_config = {
uplink_netvm_ip : Ipaddr.V4.t; (* The IP address of NetVM (our gateway) *)
uplink_our_ip : Ipaddr.V4.t; (* The IP address of our interface to NetVM *)
clients_our_ip : Ipaddr.V4.t; (* The IP address of our interface to our client VMs (their gateway) *)
}
exception Missing_key of string
(* TODO: /qubes-secondary-dns *)
let try_read_network_config db =
let get name =
match DB.KeyMap.find_opt name db with
| None -> raise (Missing_key name)
| Some value -> value in
let uplink_our_ip = get "/qubes-ip" |> Ipaddr.V4.of_string_exn in
let uplink_netvm_ip = get "/qubes-gateway" |> Ipaddr.V4.of_string_exn in
let clients_our_ip = get "/qubes-netvm-gateway" |> Ipaddr.V4.of_string_exn in
Log.info (fun f -> f "@[<v2>Got network configuration from QubesDB:@,\
NetVM IP on uplink network: %a@,\
Our IP on uplink network: %a@,\
Our IP on client networks: %a@]"
Ipaddr.V4.pp uplink_netvm_ip
Ipaddr.V4.pp uplink_our_ip
Ipaddr.V4.pp clients_our_ip);
{ uplink_netvm_ip; uplink_our_ip; clients_our_ip }
let read_network_config qubesDB =
let rec aux bindings =
try Lwt.return (try_read_network_config bindings)
with Missing_key key ->
Log.warn (fun f -> f "QubesDB key %S not (yet) present; waiting for QubesDB to change..." key);
DB.after qubesDB bindings >>= aux
in
aux (DB.bindings qubesDB)
let set_iptables_error db = Qubes.DB.write db "/qubes-iptables-error"