%%%-------------------------------------------------------------------
%%% Created : 13 Dec 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2018 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(xmpp_stream_pkix).
%% API
-export([authenticate/1, authenticate/2, get_cert_domains/1, format_error/1]).
-include("xmpp.hrl").
-include_lib("public_key/include/public_key.hrl").
-include("XmppAddr.hrl").
-type cert() :: #'OTPCertificate'{}.
%%%===================================================================
%%% API
%%%===================================================================
-spec authenticate(xmpp_stream_in:state() | xmpp_stream_out:state())
-> {ok, binary()} | {error, atom(), binary()}.
authenticate(State) ->
authenticate(State, <<"">>).
-spec authenticate(xmpp_stream_in:state() | xmpp_stream_out:state(), binary())
-> {ok, binary()} | {error, atom(), binary()}.
authenticate(#{xmlns := ?NS_SERVER,
socket := Socket} = State, Authzid) ->
Peer = maps:get(remote_server, State, Authzid),
case verify_cert(Socket) of
{ok, Cert} ->
case ejabberd_idna:domain_utf8_to_ascii(Peer) of
false ->
{error, idna_failed, Peer};
AsciiPeer ->
case lists:any(
fun(D) -> match_domain(AsciiPeer, D) end,
get_cert_domains(Cert)) of
true ->
{ok, Peer};
false ->
{error, hostname_mismatch, Peer}
end
end;
{error, Reason} ->
{error, Reason, Peer}
end;
authenticate(#{xmlns := ?NS_CLIENT,
socket := Socket, lserver := LServer}, Authzid) ->
JID = try jid:decode(Authzid)
catch _:{bad_jid, <<>>} -> jid:make(LServer);
_:{bad_jid, _} -> {error, invalid_authzid, Authzid}
end,
case JID of
#jid{user = User} ->
case verify_cert(Socket) of
{ok, Cert} ->
JIDs = get_xmpp_addrs(Cert),
get_username(JID, JIDs, LServer);
{error, Reason} ->
{error, Reason, User}
end;
Err ->
Err
end.
format_error(idna_failed) ->
{'bad-protocol', <<"Remote domain is not an IDN hostname">>};
format_error(hostname_mismatch) ->
{'not-authorized', <<"Certificate host name mismatch">>};
format_error(jid_mismatch) ->
{'not-authorized', <<"Certificate JID mismatch">>};
format_error(get_cert_failed) ->
{'bad-protocol', <<"Failed to get peer certificate">>};
format_error(invalid_authzid) ->
{'invalid-authzid', <<"Malformed JID">>};
format_error(Other) ->
{'not-authorized', erlang:atom_to_binary(Other, utf8)}.
-spec get_cert_domains(cert()) -> [binary()].
get_cert_domains(Cert) ->
TBSCert = Cert#'OTPCertificate'.tbsCertificate,
{rdnSequence, Subject} = TBSCert#'OTPTBSCertificate'.subject,
Extensions = TBSCert#'OTPTBSCertificate'.extensions,
get_domain_from_subject(lists:flatten(Subject)) ++
get_domains_from_san(Extensions).
%%%===================================================================
%%% Internal functions
%%%===================================================================
-spec verify_cert(xmpp_socket:socket()) -> {ok, cert()} | {error, atom()}.
verify_cert(Socket) ->
case xmpp_socket:get_peer_certificate(Socket, otp) of
{ok, Cert} ->
case xmpp_socket:get_verify_result(Socket) of
0 ->
{ok, Cert};
VerifyRes ->
%% TODO: return atomic errors
%% This should be improved in fast_tls
Reason = fast_tls:get_cert_verify_string(VerifyRes, Cert),
{error, erlang:binary_to_atom(Reason, utf8)}
end;
{error, _Reason} ->
{error, get_cert_failed};
error ->
{error, get_cert_failed}
end.
-spec get_domain_from_subject([#'AttributeTypeAndValue'{}]) -> [binary()].
get_domain_from_subject(AttrVals) ->
case lists:keyfind(?'id-at-commonName',
#'AttributeTypeAndValue'.type,
AttrVals) of
#'AttributeTypeAndValue'{value = {_, S}} ->
try jid:decode(iolist_to_binary(S)) of
#jid{luser = <<"">>, lresource = <<"">>, lserver = Domain} ->
[Domain];
_ ->
[]
catch _:{bad_jid, _} ->
[]
end;
_ ->
[]
end.
-spec get_domains_from_san([#'Extension'{}] | asn1_NOVALUE) -> [binary()].
get_domains_from_san(Extensions) when is_list(Extensions) ->
case lists:keyfind(?'id-ce-subjectAltName',
#'Extension'.extnID,
Extensions) of
#'Extension'{extnValue = Vals} ->
lists:flatmap(
fun({dNSName, S}) ->
[iolist_to_binary(S)];
({otherName, AnotherName}) ->
case decode_xmpp_addr(AnotherName) of
{ok, #jid{luser = <<"">>,
lresource = <<"">>,
lserver = Domain}} ->
case ejabberd_idna:domain_utf8_to_ascii(Domain) of
false ->
[];
ASCIIDomain ->
[ASCIIDomain]
end;
_ ->
[]
end;
(_) ->
[]
end, Vals);
_ ->
[]
end;
get_domains_from_san(_) ->
[].
-spec decode_xmpp_addr(#'AnotherName'{}) -> {ok, jid()} | error.
decode_xmpp_addr(#'AnotherName'{'type-id' = ?'id-on-xmppAddr',
value = XmppAddr}) ->
try 'XmppAddr':decode('XmppAddr', XmppAddr) of
{ok, JIDStr} ->
try {ok, jid:decode(iolist_to_binary(JIDStr))}
catch _:{bad_jid, _} -> error
end;
_ ->
error
catch _:_ ->
error
end;
decode_xmpp_addr(_) ->
error.
-spec get_xmpp_addrs(cert()) -> [jid()].
get_xmpp_addrs(Cert) ->
TBSCert = Cert#'OTPCertificate'.tbsCertificate,
case TBSCert#'OTPTBSCertificate'.extensions of
Extensions when is_list(Extensions) ->
case lists:keyfind(?'id-ce-subjectAltName',
#'Extension'.extnID,
Extensions) of
#'Extension'{extnValue = Vals} ->
lists:flatmap(
fun({otherName, AnotherName}) ->
case decode_xmpp_addr(AnotherName) of
{ok, JID} -> [JID];
_ -> []
end;
(_) ->
[]
end, Vals);
_ ->
[]
end;
_ ->
[]
end.
match_domain(Domain, Domain) -> true;
match_domain(Domain, Pattern) ->
DLabels = str:tokens(Domain, <<".">>),
PLabels = str:tokens(Pattern, <<".">>),
match_labels(DLabels, PLabels).
match_labels([], []) -> true;
match_labels([], [_ | _]) -> false;
match_labels([_ | _], []) -> false;
match_labels([DL | DLabels], [PL | PLabels]) ->
case lists:all(fun (C) ->
$a =< C andalso C =< $z orelse
$0 =< C andalso C =< $9 orelse
C == $- orelse C == $*
end,
binary_to_list(PL))
of
true ->
Regexp = ejabberd_regexp:sh_to_awk(PL),
case ejabberd_regexp:run(DL, Regexp) of
match -> match_labels(DLabels, PLabels);
nomatch -> false
end;
false -> false
end.
-spec get_username(jid(), [jid()], binary()) ->
{ok, binary()} | {error, jid_mismatch, binary()}.
get_username(#jid{user = User, lserver = LS}, _, LServer) when LS /= LServer ->
%% The user provided JID from different domain
{error, jid_mismatch, User};
get_username(#jid{user = <<>>}, [#jid{user = U, lserver = LS}], LServer)
when U /= <<>> andalso LS == LServer ->
%% The user didn't provide JID or username, and there is only
%% one 'non-global' JID matching current domain
{ok, U};
get_username(#jid{user = User, luser = LUser}, JIDs, LServer) when User /= <<>> ->
%% The user provided username
lists:foldl(
fun(_, {ok, _} = OK) ->
OK;
(#jid{user = <<>>, lserver = LS}, _) when LS == LServer ->
%% Found "global" JID in the certficate
%% (i.e. in the form of 'domain.com')
%% within current domain, so we force matching
{ok, User};
(#jid{luser = LU, lserver = LS}, _) when LU == LUser, LS == LServer ->
%% Found exact JID matching
{ok, User};
(_, Err) ->
Err
end, {error, jid_mismatch, User}, JIDs);
get_username(#jid{user = User}, _, _) ->
%% Nothing from above is true
{error, jid_mismatch, User}.
