%%%-------------------------------------------------------------------
%%% File : mod_privilege.erl
%%% Author : Anna Mukharram <amuhar3@gmail.com>
%%% Purpose : XEP-0356: Privileged Entity
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2022 ProcessOne
%%%
%%% This program is free software; you can redistribute it and/or
%%% modify it under the terms of the GNU General Public License as
%%% published by the Free Software Foundation; either version 2 of the
%%% License, or (at your option) any later version.
%%%
%%% This program is distributed in the hope that it will be useful,
%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
%%% General Public License for more details.
%%%
%%% You should have received a copy of the GNU General Public License along
%%% with this program; if not, write to the Free Software Foundation, Inc.,
%%% 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
%%%
%%%-------------------------------------------------------------------
-module(mod_privilege).
-author('amuhar3@gmail.com').
-protocol({xep, 356, '0.2.1', '16.09', "", ""}).
-behaviour(gen_server).
-behaviour(gen_mod).
%% API
-export([start/2, stop/1, reload/3, mod_opt_type/1, mod_options/1, depends/2]).
-export([mod_doc/0]).
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
-export([component_connected/1, component_disconnected/2,
roster_access/2, process_message/1,
process_presence_out/1, process_presence_in/1]).
-include("logger.hrl").
-include_lib("xmpp/include/xmpp.hrl").
-include("translate.hrl").
-type roster_permission() :: both | get | set.
-type presence_permission() :: managed_entity | roster.
-type message_permission() :: outgoing.
-type roster_permissions() :: [{roster_permission(), acl:acl()}].
-type presence_permissions() :: [{presence_permission(), acl:acl()}].
-type message_permissions() :: [{message_permission(), acl:acl()}].
-type access() :: [{roster, roster_permissions()} |
{presence, presence_permissions()} |
{message, message_permissions()}].
-type permissions() :: #{binary() => access()}.
-record(state, {server_host = <<"">> :: binary()}).
%%%===================================================================
%%% API
%%%===================================================================
start(Host, Opts) ->
gen_mod:start_child(?MODULE, Host, Opts).
stop(Host) ->
gen_mod:stop_child(?MODULE, Host).
reload(_Host, _NewOpts, _OldOpts) ->
ok.
mod_opt_type(roster) ->
econf:options(
#{both => econf:acl(), get => econf:acl(), set => econf:acl()});
mod_opt_type(message) ->
econf:options(
#{outgoing => econf:acl()});
mod_opt_type(presence) ->
econf:options(
#{managed_entity => econf:acl(), roster => econf:acl()}).
mod_options(_) ->
[{roster, [{both, none}, {get, none}, {set, none}]},
{presence, [{managed_entity, none}, {roster, none}]},
{message, [{outgoing,none}]}].
mod_doc() ->
#{desc =>
[?T("This module is an implementation of "
"https://xmpp.org/extensions/xep-0356.html"
"[XEP-0356: Privileged Entity]. This extension "
"allows components to have privileged access to "
"other entity data (send messages on behalf of the "
"server or on behalf of a user, get/set user roster, "
"access presence information, etc.). This may be used "
"to write powerful external components, for example "
"implementing an external "
"https://xmpp.org/extensions/xep-0163.html[PEP] or "
"https://xmpp.org/extensions/xep-0313.html[MAM] service."), "",
?T("By default a component does not have any privileged access. "
"It is worth noting that the permissions grant access to "
"the component to a specific data type for all users of "
"the virtual host on which 'mod_privilege' is loaded."), "",
?T("Make sure you have a listener configured to connect your "
"component. Check the section about listening ports for more "
"information."), "",
?T("WARNING: Security issue: Privileged access gives components "
"access to sensitive data, so permission should be granted "
"carefully, only if you trust a component."), "",
?T("NOTE: This module is complementary to _`mod_delegation`_, "
"but can also be used separately.")],
opts =>
[{roster,
#{value => ?T("Options"),
desc =>
?T("This option defines roster permissions. "
"By default no permissions are given. "
"The 'Options' are:")},
[{both,
#{value => ?T("AccessName"),
desc =>
?T("Sets read/write access to a user's roster. "
"The default value is 'none'.")}},
{get,
#{value => ?T("AccessName"),
desc =>
?T("Sets read access to a user's roster. "
"The default value is 'none'.")}},
{set,
#{value => ?T("AccessName"),
desc =>
?T("Sets write access to a user's roster. "
"The default value is 'none'.")}}]},
{message,
#{value => ?T("Options"),
desc =>
?T("This option defines permissions for messages. "
"By default no permissions are given. "
"The 'Options' are:")},
[{outgoing,
#{value => ?T("AccessName"),
desc =>
?T("The option defines an access rule for sending "
"outgoing messages by the component. "
"The default value is 'none'.")}}]},
{presence,
#{value => ?T("Options"),
desc =>
?T("This option defines permissions for presences. "
"By default no permissions are given. "
"The 'Options' are:")},
[{managed_entity,
#{value => ?T("AccessName"),
desc =>
?T("An access rule that gives permissions to "
"the component to receive server presences. "
"The default value is 'none'.")}},
{roster,
#{value => ?T("AccessName"),
desc =>
?T("An access rule that gives permissions to "
"the component to receive the presence of both "
"the users and the contacts in their roster. "
"The default value is 'none'.")}}]}],
example =>
["modules:",
" ...",
" mod_privilege:",
" roster:",
" get: all",
" presence:",
" managed_entity: all",
" message:",
" outgoing: all",
" ..."]}.
depends(_, _) ->
[].
-spec component_connected(binary()) -> ok.
component_connected(Host) ->
lists:foreach(
fun(ServerHost) ->
Proc = gen_mod:get_module_proc(ServerHost, ?MODULE),
gen_server:cast(Proc, {component_connected, Host})
end, ejabberd_option:hosts()).
-spec component_disconnected(binary(), binary()) -> ok.
component_disconnected(Host, _Reason) ->
lists:foreach(
fun(ServerHost) ->
Proc = gen_mod:get_module_proc(ServerHost, ?MODULE),
gen_server:cast(Proc, {component_disconnected, Host})
end, ejabberd_option:hosts()).
-spec process_message(stanza()) -> stop | ok.
process_message(#message{from = #jid{luser = <<"">>, lresource = <<"">>} = From,
to = #jid{lresource = <<"">>} = To,
lang = Lang, type = T} = Msg) when T /= error ->
Host = From#jid.lserver,
ServerHost = To#jid.lserver,
Permissions = get_permissions(ServerHost),
case maps:find(Host, Permissions) of
{ok, Access} ->
case proplists:get_value(message, Access, none) of
outgoing ->
forward_message(Msg);
_ ->
Txt = ?T("Insufficient privilege"),
Err = xmpp:err_forbidden(Txt, Lang),
ejabberd_router:route_error(Msg, Err)
end,
stop;
error ->
%% Component is disconnected
ok
end;
process_message(_Stanza) ->
ok.
-spec roster_access(boolean(), iq()) -> boolean().
roster_access(true, _) ->
true;
roster_access(false, #iq{from = From, to = To, type = Type}) ->
Host = From#jid.lserver,
ServerHost = To#jid.lserver,
Permissions = get_permissions(ServerHost),
case maps:find(Host, Permissions) of
{ok, Access} ->
Permission = proplists:get_value(roster, Access, none),
(Permission == both)
orelse (Permission == get andalso Type == get)
orelse (Permission == set andalso Type == set);
error ->
%% Component is disconnected
false
end.
-spec process_presence_out({stanza(), ejabberd_c2s:state()}) -> {stanza(), ejabberd_c2s:state()}.
process_presence_out({#presence{
from = #jid{luser = LUser, lserver = LServer} = From,
to = #jid{luser = LUser, lserver = LServer, lresource = <<"">>},
type = Type} = Pres, C2SState})
when Type == available; Type == unavailable ->
%% Self-presence processing
Permissions = get_permissions(LServer),
lists:foreach(
fun({Host, Access}) ->
Permission = proplists:get_value(presence, Access, none),
if Permission == roster; Permission == managed_entity ->
To = jid:make(Host),
ejabberd_router:route(
xmpp:set_from_to(Pres, From, To));
true ->
ok
end
end, maps:to_list(Permissions)),
{Pres, C2SState};
process_presence_out(Acc) ->
Acc.
-spec process_presence_in({stanza(), ejabberd_c2s:state()}) -> {stanza(), ejabberd_c2s:state()}.
process_presence_in({#presence{
from = #jid{luser = U, lserver = S} = From,
to = #jid{luser = LUser, lserver = LServer},
type = Type} = Pres, C2SState})
when {U, S} /= {LUser, LServer} andalso
(Type == available orelse Type == unavailable) ->
Permissions = get_permissions(LServer),
lists:foreach(
fun({Host, Access}) ->
case proplists:get_value(presence, Access, none) of
roster ->
Permission = proplists:get_value(roster, Access, none),
if Permission == both; Permission == get ->
To = jid:make(Host),
ejabberd_router:route(
xmpp:set_from_to(Pres, From, To));
true ->
ok
end;
_ ->
ok
end
end, maps:to_list(Permissions)),
{Pres, C2SState};
process_presence_in(Acc) ->
Acc.
%%%===================================================================
%%% gen_server callbacks
%%%===================================================================
init([Host|_]) ->
process_flag(trap_exit, true),
catch ets:new(?MODULE,
[named_table, public,
{heir, erlang:group_leader(), none}]),
ejabberd_hooks:add(component_connected, ?MODULE,
component_connected, 50),
ejabberd_hooks:add(component_disconnected, ?MODULE,
component_disconnected, 50),
ejabberd_hooks:add(local_send_to_resource_hook, Host, ?MODULE,
process_message, 50),
ejabberd_hooks:add(roster_remote_access, Host, ?MODULE,
roster_access, 50),
ejabberd_hooks:add(user_send_packet, Host, ?MODULE,
process_presence_out, 50),
ejabberd_hooks:add(user_receive_packet, Host, ?MODULE,
process_presence_in, 50),
{ok, #state{server_host = Host}}.
handle_call(Request, From, State) ->
?WARNING_MSG("Unexpected call from ~p: ~p", [From, Request]),
{noreply, State}.
handle_cast({component_connected, Host}, State) ->
ServerHost = State#state.server_host,
From = jid:make(ServerHost),
To = jid:make(Host),
RosterPerm = get_roster_permission(ServerHost, Host),
PresencePerm = get_presence_permission(ServerHost, Host),
MessagePerm = get_message_permission(ServerHost, Host),
if RosterPerm /= none; PresencePerm /= none; MessagePerm /= none ->
Priv = #privilege{perms = [#privilege_perm{access = message,
type = MessagePerm},
#privilege_perm{access = roster,
type = RosterPerm},
#privilege_perm{access = presence,
type = PresencePerm}]},
?INFO_MSG("Granting permissions to external "
"component '~ts': roster = ~ts, presence = ~ts, "
"message = ~ts",
[Host, RosterPerm, PresencePerm, MessagePerm]),
Msg = #message{from = From, to = To, sub_els = [Priv]},
ejabberd_router:route(Msg),
Permissions = maps:put(Host, [{roster, RosterPerm},
{presence, PresencePerm},
{message, MessagePerm}],
get_permissions(ServerHost)),
ets:insert(?MODULE, {ServerHost, Permissions}),
{noreply, State};
true ->
?INFO_MSG("Granting no permissions to external component '~ts'",
[Host]),
{noreply, State}
end;
handle_cast({component_disconnected, Host}, State) ->
ServerHost = State#state.server_host,
Permissions = maps:remove(Host, get_permissions(ServerHost)),
case maps:size(Permissions) of
0 -> ets:delete(?MODULE, ServerHost);
_ -> ets:insert(?MODULE, {ServerHost, Permissions})
end,
{noreply, State};
handle_cast(Msg, State) ->
?WARNING_MSG("Unexpected cast: ~p", [Msg]),
{noreply, State}.
handle_info(Info, State) ->
?WARNING_MSG("Unexpected info: ~p", [Info]),
{noreply, State}.
terminate(_Reason, State) ->
Host = State#state.server_host,
case gen_mod:is_loaded_elsewhere(Host, ?MODULE) of
false ->
ejabberd_hooks:delete(component_connected, ?MODULE,
component_connected, 50),
ejabberd_hooks:delete(component_disconnected, ?MODULE,
component_disconnected, 50);
true ->
ok
end,
ejabberd_hooks:delete(local_send_to_resource_hook, Host, ?MODULE,
process_message, 50),
ejabberd_hooks:delete(roster_remote_access, Host, ?MODULE,
roster_access, 50),
ejabberd_hooks:delete(user_send_packet, Host, ?MODULE,
process_presence_out, 50),
ejabberd_hooks:delete(user_receive_packet, Host, ?MODULE,
process_presence_in, 50),
ets:delete(?MODULE, Host).
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%%%===================================================================
%%% Internal functions
%%%===================================================================
-spec get_permissions(binary()) -> permissions().
get_permissions(ServerHost) ->
try ets:lookup_element(?MODULE, ServerHost, 2)
catch _:badarg -> #{}
end.
-spec forward_message(message()) -> ok.
forward_message(#message{to = To} = Msg) ->
ServerHost = To#jid.lserver,
Lang = xmpp:get_lang(Msg),
CodecOpts = ejabberd_config:codec_options(),
try xmpp:try_subtag(Msg, #privilege{}) of
#privilege{forwarded = #forwarded{sub_els = [SubEl]}} ->
try xmpp:decode(SubEl, ?NS_CLIENT, CodecOpts) of
#message{} = NewMsg ->
case NewMsg#message.from of
#jid{lresource = <<"">>, lserver = ServerHost} ->
ejabberd_router:route(NewMsg);
_ ->
Lang = xmpp:get_lang(Msg),
Txt = ?T("Invalid 'from' attribute in forwarded message"),
Err = xmpp:err_forbidden(Txt, Lang),
ejabberd_router:route_error(Msg, Err)
end;
_ ->
Txt = ?T("Message not found in forwarded payload"),
Err = xmpp:err_bad_request(Txt, Lang),
ejabberd_router:route_error(Msg, Err)
catch _:{xmpp_codec, Why} ->
Txt = xmpp:io_format_error(Why),
Err = xmpp:err_bad_request(Txt, Lang),
ejabberd_router:route_error(Msg, Err)
end;
_ ->
Txt = ?T("No <forwarded/> element found"),
Err = xmpp:err_bad_request(Txt, Lang),
ejabberd_router:route_error(Msg, Err)
catch _:{xmpp_codec, Why} ->
Txt = xmpp:io_format_error(Why),
Err = xmpp:err_bad_request(Txt, Lang),
ejabberd_router:route_error(Msg, Err)
end.
-spec get_roster_permission(binary(), binary()) -> roster_permission() | none.
get_roster_permission(ServerHost, Host) ->
Perms = mod_privilege_opt:roster(ServerHost),
case match_rule(ServerHost, Host, Perms, both) of
allow ->
both;
deny ->
Get = match_rule(ServerHost, Host, Perms, get),
Set = match_rule(ServerHost, Host, Perms, set),
if Get == allow, Set == allow -> both;
Get == allow -> get;
Set == allow -> set;
true -> none
end
end.
-spec get_message_permission(binary(), binary()) -> message_permission() | none.
get_message_permission(ServerHost, Host) ->
Perms = mod_privilege_opt:message(ServerHost),
case match_rule(ServerHost, Host, Perms, outgoing) of
allow -> outgoing;
deny -> none
end.
-spec get_presence_permission(binary(), binary()) -> presence_permission() | none.
get_presence_permission(ServerHost, Host) ->
Perms = mod_privilege_opt:presence(ServerHost),
case match_rule(ServerHost, Host, Perms, roster) of
allow ->
roster;
deny ->
case match_rule(ServerHost, Host, Perms, managed_entity) of
allow -> managed_entity;
deny -> none
end
end.
-spec match_rule(binary(), binary(), roster_permissions(), roster_permission()) -> allow | deny;
(binary(), binary(), presence_permissions(), presence_permission()) -> allow | deny;
(binary(), binary(), message_permissions(), message_permission()) -> allow | deny.
match_rule(ServerHost, Host, Perms, Type) ->
Access = proplists:get_value(Type, Perms, none),
acl:match_rule(ServerHost, Access, jid:make(Host)).
