mirror of
https://github.com/mirage/qubes-mirage-firewall.git
synced 2024-12-29 00:56:13 -05:00
d094b20950
in the callback to "Xs_client.wait", all operations are tracked and new watches are installed (that are never removed, due to xenstore's xs_handle "accessed_path" never removes any elements of the "accessed_paths" (a mutable StringSet). So, whatever is done in the callback of wait needs to take care (if returning EAGAIN and thus forcing xenstore to continue waiting/watching) that accesses are tracked. Our way out is to create a fresh client and read the IP address with that new client -> the watcher isn't extended -> no dangling (leaking) watches, and no leaking only-expanding StringSet.
169 lines
6.4 KiB
OCaml
169 lines
6.4 KiB
OCaml
(* Copyright (C) 2015, Thomas Leonard <thomas.leonard@unikernel.com>
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See the README file for details. *)
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open Lwt.Infix
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open Qubes
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open Astring
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let src = Logs.Src.create "dao" ~doc:"QubesDB data access"
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module Log = (val Logs.src_log src : Logs.LOG)
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module ClientVif = struct
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type t = {
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domid : int;
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device_id : int;
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}
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let pp f { domid; device_id } = Fmt.pf f "{domid=%d;device_id=%d}" domid device_id
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let compare = compare
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end
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module VifMap = struct
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include Map.Make(ClientVif)
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let rec of_list = function
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| [] -> empty
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| (k, v) :: rest -> add k v (of_list rest)
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let find key t =
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try Some (find key t)
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with Not_found -> None
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end
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let directory ~handle dir =
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Xen_os.Xs.directory handle dir >|= function
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| [""] -> [] (* XenStore client bug *)
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| items -> items
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let db_root client_ip =
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"/qubes-firewall/" ^ (Ipaddr.V4.to_string client_ip)
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let read_rules rules client_ip =
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let root = db_root client_ip in
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let rec get_rule n l : (Pf_qubes.Parse_qubes.rule list, string) result =
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let pattern = root ^ "/" ^ Printf.sprintf "%04d" n in
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Log.debug (fun f -> f "reading %s" pattern);
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match Qubes.DB.KeyMap.find_opt pattern rules with
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| None ->
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Log.debug (fun f -> f "rule %d does not exist; won't look for more" n);
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Ok (List.rev l)
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| Some rule ->
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Log.debug (fun f -> f "rule %d: %s" n rule);
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match Pf_qubes.Parse_qubes.parse_qubes ~number:n rule with
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| Error e -> Log.warn (fun f -> f "Error parsing rule %d: %s" n e); Error e
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| Ok rule ->
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Log.debug (fun f -> f "parsed rule: %a" Pf_qubes.Parse_qubes.pp_rule rule);
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get_rule (n+1) (rule :: l)
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in
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match get_rule 0 [] with
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| Ok l -> l
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| Error e ->
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Log.warn (fun f -> f "Defaulting to deny-all because of rule parse failure (%s)" e);
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[ Pf_qubes.Parse_qubes.({action = Drop;
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proto = None;
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specialtarget = None;
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dst = `any;
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dstports = None;
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icmp_type = None;
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number = 0;})]
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let vifs client domid =
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match String.to_int domid with
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| None -> Log.err (fun f -> f "Invalid domid %S" domid); Lwt.return []
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| Some domid ->
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let path = Printf.sprintf "backend/vif/%d" domid in
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Xen_os.Xs.immediate client (fun handle ->
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directory ~handle path >>=
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Lwt_list.filter_map_p (fun device_id ->
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match String.to_int device_id with
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| None -> Log.err (fun f -> f "Invalid device ID %S for domid %d" device_id domid); Lwt.return_none
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| Some device_id ->
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let vif = { ClientVif.domid; device_id } in
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Lwt.try_bind
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(fun () -> Xen_os.Xs.read handle (Printf.sprintf "%s/%d/ip" path device_id))
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(fun client_ip ->
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let client_ip' = match String.cuts ~sep:" " client_ip with
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| [] -> Log.err (fun m -> m "unexpected empty list"); ""
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| [ ip ] -> ip
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| ip::rest ->
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Log.warn (fun m -> m "ignoring IPs %s from %a, we support one IP per client"
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(String.concat ~sep:" " rest) ClientVif.pp vif);
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ip
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in
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match Ipaddr.V4.of_string client_ip' with
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| Ok ip -> Lwt.return (Some (vif, ip))
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| Error `Msg msg ->
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Log.err (fun f -> f "Error parsing IP address of %a from %s: %s"
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ClientVif.pp vif client_ip msg);
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Lwt.return None
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)
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(function
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| Xs_protocol.Enoent _ -> Lwt.return None
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| ex ->
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Log.err (fun f -> f "Error getting IP address of %a: %s"
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ClientVif.pp vif (Printexc.to_string ex));
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Lwt.return None
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)
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))
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let watch_clients fn =
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Xen_os.Xs.make () >>= fun xs ->
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let backend_vifs = "backend/vif" in
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Log.info (fun f -> f "Watching %s" backend_vifs);
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Xen_os.Xs.wait xs (fun handle ->
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begin Lwt.catch
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(fun () -> directory ~handle backend_vifs)
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(function
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| Xs_protocol.Enoent _ -> Lwt.return []
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| ex -> Lwt.fail ex)
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end >>= fun items ->
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Xen_os.Xs.make () >>= fun xs ->
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Lwt_list.map_p (vifs xs) items >>= fun items ->
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fn (List.concat items |> VifMap.of_list);
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(* Wait for further updates *)
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Lwt.fail Xs_protocol.Eagain
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)
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type network_config = {
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uplink_netvm_ip : Ipaddr.V4.t; (* The IP address of NetVM (our gateway) *)
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uplink_our_ip : Ipaddr.V4.t; (* The IP address of our interface to NetVM *)
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clients_our_ip : Ipaddr.V4.t; (* The IP address of our interface to our client VMs (their gateway) *)
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dns : Ipaddr.V4.t;
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dns2 : Ipaddr.V4.t;
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}
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exception Missing_key of string
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let try_read_network_config db =
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let get name =
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match DB.KeyMap.find_opt name db with
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| None -> raise (Missing_key name)
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| Some value -> value in
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let uplink_our_ip = get "/qubes-ip" |> Ipaddr.V4.of_string_exn in
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let uplink_netvm_ip = get "/qubes-gateway" |> Ipaddr.V4.of_string_exn in
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let clients_our_ip = get "/qubes-netvm-gateway" |> Ipaddr.V4.of_string_exn in
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let dns = get "/qubes-primary-dns" |> Ipaddr.V4.of_string_exn in
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let dns2 = get "/qubes-secondary-dns" |> Ipaddr.V4.of_string_exn in
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Log.info (fun f -> f "@[<v2>Got network configuration from QubesDB:@,\
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NetVM IP on uplink network: %a@,\
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Our IP on uplink network: %a@,\
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Our IP on client networks: %a@,\
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DNS primary resolver: %a@,\
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DNS secondary resolver: %a@]"
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Ipaddr.V4.pp uplink_netvm_ip
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Ipaddr.V4.pp uplink_our_ip
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Ipaddr.V4.pp clients_our_ip
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Ipaddr.V4.pp dns
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Ipaddr.V4.pp dns2);
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{ uplink_netvm_ip; uplink_our_ip; clients_our_ip ; dns ; dns2 }
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let read_network_config qubesDB =
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let rec aux bindings =
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try Lwt.return (try_read_network_config bindings)
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with Missing_key key ->
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Log.warn (fun f -> f "QubesDB key %S not (yet) present; waiting for QubesDB to change..." key);
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DB.after qubesDB bindings >>= aux
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in
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aux (DB.bindings qubesDB)
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let set_iptables_error db = Qubes.DB.write db "/qubes-iptables-error"
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