%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2008-2012. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
%%
-module(ssh_auth).
-include_lib("public_key/include/public_key.hrl").
-include("ssh.hrl").
-include("ssh_auth.hrl").
-include("ssh_transport.hrl").
-export([publickey_msg/1, password_msg/1, keyboard_interactive_msg/1,
service_request_msg/1, init_userauth_request_msg/1,
userauth_request_msg/1, handle_userauth_request/3,
handle_userauth_info_request/3, handle_userauth_info_response/2,
userauth_messages/0
]).
%%--------------------------------------------------------------------
%%% Internal application API
%%--------------------------------------------------------------------
publickey_msg([Alg, #ssh{user = User,
session_id = SessionId,
service = Service,
opts = Opts} = Ssh]) ->
Hash = sha, %% Maybe option?!
ssh_bits:install_messages(userauth_pk_messages()),
case ssh_file:private_identity_key(Alg, Opts) of
{ok, Key} ->
PubKeyBlob = ssh_file:encode_public_key(Key),
SigData = build_sig_data(SessionId,
User, Service, PubKeyBlob, Alg),
Sig = sign(SigData, Hash, Key),
SigBlob = list_to_binary([?string(Alg), ?binary(Sig)]),
ssh_transport:ssh_packet(
#ssh_msg_userauth_request{user = User,
service = Service,
method = "publickey",
data = [?TRUE,
?string(Alg),
?binary(PubKeyBlob),
?binary(SigBlob)]},
Ssh);
_Error ->
not_ok
end.
password_msg([#ssh{opts = Opts, io_cb = IoCb,
user = User, service = Service} = Ssh]) ->
ssh_bits:install_messages(userauth_passwd_messages()),
Password = case proplists:get_value(password, Opts) of
undefined ->
IoCb:read_password("ssh password: ");
PW ->
PW
end,
ssh_transport:ssh_packet(
#ssh_msg_userauth_request{user = User,
service = Service,
method = "password",
data =
<<?BOOLEAN(?FALSE),
?STRING(list_to_binary(Password))>>},
Ssh).
%% See RFC 4256 for info on keyboard-interactive
keyboard_interactive_msg([#ssh{user = User,
service = Service} = Ssh]) ->
ssh_bits:install_messages(userauth_keyboard_interactive_messages()),
ssh_transport:ssh_packet(
#ssh_msg_userauth_request{user = User,
service = Service,
method = "keyboard-interactive",
data = << ?STRING(<<"">>),
?STRING(<<>>) >> },
Ssh).
service_request_msg(Ssh) ->
ssh_transport:ssh_packet(#ssh_msg_service_request{name = "ssh-userauth"},
Ssh#ssh{service = "ssh-userauth"}).
init_userauth_request_msg(#ssh{opts = Opts} = Ssh) ->
case user_name(Opts) of
{ok, User} ->
Msg = #ssh_msg_userauth_request{user = User,
service = "ssh-connection",
method = "none",
data = <<>>},
FirstAlg = algorithm(proplists:get_value(public_key_alg, Opts,
?PREFERRED_PK_ALG)),
SecondAlg = other_alg(FirstAlg),
AllowUserInt = proplists:get_value(allow_user_interaction, Opts,
true),
Prefs = method_preference(FirstAlg, SecondAlg, AllowUserInt),
ssh_transport:ssh_packet(Msg, Ssh#ssh{user = User,
userauth_preference = Prefs,
userauth_methods = none,
service = "ssh-connection"});
{error, no_user} ->
ErrStr = "Could not determine the users name",
throw(#ssh_msg_disconnect{code = ?SSH_DISCONNECT_ILLEGAL_USER_NAME,
description = ErrStr,
language = "en"})
end.
userauth_request_msg(#ssh{userauth_preference = []} = Ssh) ->
Msg = #ssh_msg_disconnect{code =
?SSH_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE,
description = "Unable to connect using the available"
" authentication methods",
language = "en"},
{disconnect, Msg, ssh_transport:ssh_packet(Msg, Ssh)};
userauth_request_msg(#ssh{userauth_methods = Methods,
userauth_preference = [{Pref, Module,
Function, Args} | Prefs]}
= Ssh0) ->
Ssh = Ssh0#ssh{userauth_preference = Prefs},
case lists:member(Pref, Methods) of
true ->
case Module:Function(Args ++ [Ssh]) of
not_ok ->
userauth_request_msg(Ssh);
Result ->
Result
end;
false ->
userauth_request_msg(Ssh)
end.
handle_userauth_request(#ssh_msg_service_request{name =
Name = "ssh-userauth"},
_, Ssh) ->
{ok, ssh_transport:ssh_packet(#ssh_msg_service_accept{name = Name},
Ssh#ssh{service = "ssh-connection"})};
handle_userauth_request(#ssh_msg_userauth_request{user = User,
service = "ssh-connection",
method = "password",
data = Data}, _,
#ssh{opts = Opts} = Ssh) ->
<<_:8, ?UINT32(Sz), BinPwd:Sz/binary>> = Data,
Password = binary_to_list(BinPwd),
case check_password(User, Password, Opts) of
true ->
{authorized, User,
ssh_transport:ssh_packet(#ssh_msg_userauth_success{}, Ssh)};
false ->
{not_authorized, {User, {passwd, Password}},
ssh_transport:ssh_packet(#ssh_msg_userauth_failure{
authentications = "",
partial_success = false}, Ssh)}
end;
handle_userauth_request(#ssh_msg_userauth_request{user = User,
service = "ssh-connection",
method = "none"}, _,
#ssh{userauth_supported_methods = Methods} = Ssh) ->
{not_authorized, {User, undefined},
ssh_transport:ssh_packet(
#ssh_msg_userauth_failure{authentications = Methods,
partial_success = false}, Ssh)};
handle_userauth_request(#ssh_msg_userauth_request{user = User,
service = "ssh-connection",
method = "publickey",
data = Data},
SessionId, #ssh{opts = Opts} = Ssh) ->
<<?BYTE(HaveSig), ?UINT32(ALen), BAlg:ALen/binary,
?UINT32(KLen), KeyBlob:KLen/binary, SigWLen/binary>> = Data,
Alg = binary_to_list(BAlg),
case HaveSig of
?TRUE ->
case verify_sig(SessionId, User, "ssh-connection", Alg,
KeyBlob, SigWLen, Opts) of
true ->
{authorized, User,
ssh_transport:ssh_packet(
#ssh_msg_userauth_success{}, Ssh)};
false ->
{not_authorized, {User, {error, "Invalid signature"}},
ssh_transport:ssh_packet(#ssh_msg_userauth_failure{
authentications="publickey,password",
partial_success = false}, Ssh)}
end;
?FALSE ->
ssh_bits:install_messages(userauth_pk_messages()),
{not_authorized, {User, undefined},
ssh_transport:ssh_packet(
#ssh_msg_userauth_pk_ok{algorithm_name = Alg,
key_blob = KeyBlob}, Ssh)}
end;
handle_userauth_request(#ssh_msg_userauth_request{user = User,
service = "ssh-connection",
method = Other}, _,
#ssh{userauth_supported_methods = Methods} = Ssh) ->
{not_authorized, {User, {authmethod, Other}},
ssh_transport:ssh_packet(
#ssh_msg_userauth_failure{authentications = Methods,
partial_success = false}, Ssh)}.
handle_userauth_info_request(
#ssh_msg_userauth_info_request{name = Name,
instruction = Instr,
num_prompts = NumPrompts,
data = Data}, IoCb,
#ssh{opts = Opts} = Ssh) ->
PromptInfos = decode_keyboard_interactive_prompts(NumPrompts,Data),
Resps = keyboard_interact_get_responses(IoCb, Opts,
Name, Instr, PromptInfos),
RespBin = list_to_binary(
lists:map(fun(S) -> <<?STRING(list_to_binary(S))>> end,
Resps)),
{ok,
ssh_transport:ssh_packet(
#ssh_msg_userauth_info_response{num_responses = NumPrompts,
data = RespBin}, Ssh)}.
handle_userauth_info_response(#ssh_msg_userauth_info_response{},
_Auth) ->
throw(#ssh_msg_disconnect{code = ?SSH_DISCONNECT_SERVICE_NOT_AVAILABLE,
description = "Server does not support"
"keyboard-interactive",
language = "en"}).
userauth_messages() ->
[ {ssh_msg_userauth_request, ?SSH_MSG_USERAUTH_REQUEST,
[string,
string,
string,
'...']},
{ssh_msg_userauth_failure, ?SSH_MSG_USERAUTH_FAILURE,
[string,
boolean]},
{ssh_msg_userauth_success, ?SSH_MSG_USERAUTH_SUCCESS,
[]},
{ssh_msg_userauth_banner, ?SSH_MSG_USERAUTH_BANNER,
[string,
string]}].
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
method_preference(Alg1, Alg2, true) ->
[{"publickey", ?MODULE, publickey_msg, [Alg1]},
{"publickey", ?MODULE, publickey_msg,[Alg2]},
{"password", ?MODULE, password_msg, []},
{"keyboard-interactive", ?MODULE, keyboard_interactive_msg, []}
];
method_preference(Alg1, Alg2, false) ->
[{"publickey", ?MODULE, publickey_msg, [Alg1]},
{"publickey", ?MODULE, publickey_msg,[Alg2]},
{"password", ?MODULE, password_msg, []}
].
user_name(Opts) ->
Env = case os:type() of
{win32, _} ->
"USERNAME";
{unix, _} ->
"LOGNAME"
end,
case proplists:get_value(user, Opts, os:getenv(Env)) of
false ->
case os:getenv("USER") of
false ->
{error, no_user};
User ->
{ok, User}
end;
User ->
{ok, User}
end.
check_password(User, Password, Opts) ->
case proplists:get_value(pwdfun, Opts) of
undefined ->
Static = get_password_option(Opts, User),
Password == Static;
Cheker ->
Cheker(User, Password)
end.
get_password_option(Opts, User) ->
Passwords = proplists:get_value(user_passwords, Opts, []),
case lists:keysearch(User, 1, Passwords) of
{value, {User, Pw}} -> Pw;
false -> proplists:get_value(password, Opts, false)
end.
verify_sig(SessionId, User, Service, Alg, KeyBlob, SigWLen, Opts) ->
{ok, Key} = ssh_file:decode_public_key_v2(KeyBlob, Alg),
case ssh_file:lookup_user_key(Key, User, Alg, Opts) of
{ok, OurKey} ->
case OurKey of
Key ->
PlainText = build_sig_data(SessionId, User,
Service, KeyBlob, Alg),
<<?UINT32(AlgSigLen), AlgSig:AlgSigLen/binary>> = SigWLen,
<<?UINT32(AlgLen), _Alg:AlgLen/binary,
?UINT32(SigLen), Sig:SigLen/binary>> = AlgSig,
verify(PlainText, sha, Sig, Key);
_ ->
{error, key_unacceptable}
end;
Error -> Error
end.
build_sig_data(SessionId, User, Service, KeyBlob, Alg) ->
Sig = [?binary(SessionId),
?SSH_MSG_USERAUTH_REQUEST,
?string(User),
?string(Service),
?binary(<<"publickey">>),
?TRUE,
?string(Alg),
?binary(KeyBlob)],
list_to_binary(Sig).
algorithm(ssh_rsa) ->
"ssh-rsa";
algorithm(ssh_dsa) ->
"ssh-dss".
sign(SigData, Hash, #'DSAPrivateKey'{} = Key) ->
DerSignature = public_key:sign(SigData, Hash, Key),
#'Dss-Sig-Value'{r = R, s = S} = public_key:der_decode('Dss-Sig-Value', DerSignature),
<<R:160/big-unsigned-integer, S:160/big-unsigned-integer>>;
sign(SigData, Hash, Key) ->
public_key:sign(SigData, Hash, Key).
verify(PlainText, Hash, Sig, {_, #'Dss-Parms'{}} = Key) ->
<<R:160/big-unsigned-integer, S:160/big-unsigned-integer>> = Sig,
Signature = public_key:der_encode('Dss-Sig-Value', #'Dss-Sig-Value'{r = R, s = S}),
public_key:verify(PlainText, Hash, Signature, Key);
verify(PlainText, Hash, Sig, Key) ->
public_key:verify(PlainText, Hash, Sig, Key).
decode_keyboard_interactive_prompts(NumPrompts, Data) ->
Types = lists:append(lists:duplicate(NumPrompts, [string, boolean])),
pairwise_tuplify(ssh_bits:decode(Data, Types)).
pairwise_tuplify([E1, E2 | Rest]) -> [{E1, E2} | pairwise_tuplify(Rest)];
pairwise_tuplify([]) -> [].
keyboard_interact_get_responses(IoCb, Opts, Name, Instr, PromptInfos) ->
NumPrompts = length(PromptInfos),
case proplists:get_value(keyboard_interact_fun, Opts) of
undefined when NumPrompts == 1 ->
%% Special case/fallback for just one prompt
%% (assumed to be the password prompt)
case proplists:get_value(password, Opts) of
undefined -> keyboard_interact(IoCb, Name, Instr, PromptInfos);
PW -> [PW]
end;
undefined ->
keyboard_interact(IoCb, Name, Instr, PromptInfos);
KbdInteractFun ->
Prompts = lists:map(fun({Prompt, _Echo}) -> Prompt end,
PromptInfos),
case KbdInteractFun(Name, Instr, Prompts) of
Rs when length(Rs) == NumPrompts ->
Rs;
Rs ->
erlang:error({mismatching_number_of_responses,
{got,Rs},
{expected,NumPrompts}})
end
end.
keyboard_interact(IoCb, Name, Instr, Prompts) ->
if Name /= "" -> IoCb:format("~s", [Name]);
true -> ok
end,
if Instr /= "" -> IoCb:format("~s", [Instr]);
true -> ok
end,
lists:map(fun({Prompt, true}) -> IoCb:read_line(Prompt);
({Prompt, false}) -> IoCb:read_password(Prompt)
end,
Prompts).
userauth_passwd_messages() ->
[
{ssh_msg_userauth_passwd_changereq, ?SSH_MSG_USERAUTH_PASSWD_CHANGEREQ,
[string,
string]}
].
userauth_keyboard_interactive_messages() ->
[ {ssh_msg_userauth_info_request, ?SSH_MSG_USERAUTH_INFO_REQUEST,
[string,
string,
string,
uint32,
'...']},
{ssh_msg_userauth_info_response, ?SSH_MSG_USERAUTH_INFO_RESPONSE,
[uint32,
'...']}
].
userauth_pk_messages() ->
[ {ssh_msg_userauth_pk_ok, ?SSH_MSG_USERAUTH_PK_OK,
[string, % algorithm name
binary]} % key blob
].
other_alg("ssh-rsa") ->
"ssh-dss";
other_alg("ssh-dss") ->
"ssh-rsa".
