Merge branch 'hans/ssh/codenomicon_degradation/OTP-12784' into maint-17

* hans/ssh/codenomicon_degradation/OTP-12784:
  ssh: update ssh version
  ssh: Plain text message returned for invalid version exchange
  ssh: Implement keyboard_interactive on server side
  ssh: Check e and f parameters in kexdh
  ssh: Set max num algoritms in msg_kexinit negotiation

4 files changed, 151 insertions, 29 deletions

diff --git a/lib/ssh/src/ssh.erl b/lib/ssh/src/ssh.erl
index 71e7d77475..7ed17618e7 100644
--- a/lib/ssh/src/ssh.erl
+++ b/lib/ssh/src/ssh.erl
@@ -331,6 +331,8 @@ handle_option([{exec, _} = Opt | Rest], SocketOptions, SshOptions) ->
     handle_option(Rest, SocketOptions, [handle_ssh_option(Opt) | SshOptions]);
 handle_option([{auth_methods, _} = Opt | Rest], SocketOptions, SshOptions) ->
     handle_option(Rest, SocketOptions, [handle_ssh_option(Opt) | SshOptions]);
+handle_option([{auth_method_kb_interactive_data, _} = Opt | Rest], SocketOptions, SshOptions) ->
+    handle_option(Rest, SocketOptions, [handle_ssh_option(Opt) | SshOptions]);
 handle_option([{pref_public_key_algs, _} = Opt | Rest], SocketOptions, SshOptions) ->
     handle_option(Rest, SocketOptions, [handle_ssh_option(Opt) | SshOptions]);
 handle_option([{quiet_mode, _} = Opt|Rest], SocketOptions, SshOptions) ->
@@ -411,6 +413,13 @@ handle_ssh_option({exec, Function} = Opt) when is_function(Function) ->
     Opt;
 handle_ssh_option({auth_methods, Value} = Opt)  when is_list(Value) ->
     Opt;
+handle_ssh_option({auth_method_kb_interactive_data, {Name,Instruction,Prompt,Echo}} = Opt) when is_list(Name),
+												is_list(Instruction),
+												is_list(Prompt),
+												is_boolean(Echo) ->
+    Opt;
+handle_ssh_option({auth_method_kb_interactive_data, F} = Opt) when is_function(F,3) ->
+    Opt;
 handle_ssh_option({infofun, Value} = Opt)  when is_function(Value) ->
     Opt;
 handle_ssh_option({connectfun, Value} = Opt) when is_function(Value) ->
diff --git a/lib/ssh/src/ssh_auth.erl b/lib/ssh/src/ssh_auth.erl
index 45c4d52d7e..9d1ab14ce9 100644
--- a/lib/ssh/src/ssh_auth.erl
+++ b/lib/ssh/src/ssh_auth.erl
@@ -259,6 +259,54 @@ handle_userauth_request(#ssh_msg_userauth_request{user = User,
 
 handle_userauth_request(#ssh_msg_userauth_request{user = User,
 						  service = "ssh-connection",
+						  method = "keyboard-interactive",
+						  data = _},
+			_, #ssh{opts = Opts} = Ssh) ->
+    %% RFC4256
+    %% The data field contains:
+    %%   - language tag (deprecated). If =/=[] SHOULD use it however. We skip
+    %%                                it for simplicity.
+    %%   - submethods. "... the user can give a hint of which actual methods
+    %%                  he wants to use. ...".  It's a "MAY use" so we skip
+    %%                  it. It also needs an understanding between the client
+    %%                  and the server.
+    %%                  
+    %% "The server MUST reply with an SSH_MSG_USERAUTH_SUCCESS,
+    %%  SSH_MSG_USERAUTH_FAILURE, or SSH_MSG_USERAUTH_INFO_REQUEST message."
+    Default = {"SSH server",
+	       "Enter password for \""++User++"\"",
+	       "pwd: ",
+	       false},
+
+    {Name, Instruction, Prompt, Echo} =
+	case proplists:get_value(auth_method_kb_interactive_data, Opts) of
+	    undefined -> 
+		Default;
+	    {_,_,_,_}=V -> 
+		V;
+	    F when is_function(F) ->
+		{_,PeerName} = Ssh#ssh.peer,
+		F(PeerName, User, "ssh-connection")
+	end,
+    EchoEnc = case Echo of
+		  true -> <<?TRUE>>;
+		  false -> <<?FALSE>>
+	      end,
+    Msg = #ssh_msg_userauth_info_request{name = unicode:characters_to_list(Name),
+					 instruction = unicode:characters_to_list(Instruction),
+					 language_tag = "",
+					 num_prompts = 1,
+					 data = <<?STRING(unicode:characters_to_binary(Prompt)),
+						  EchoEnc/binary
+						>>
+					},
+    {not_authorized, {User, undefined}, 
+     ssh_transport:ssh_packet(Msg, Ssh#ssh{user = User,
+					   opts = [{max_kb_tries,3},{kb_userauth_info_msg,Msg}|Opts]
+					  })};
+
+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}}, 
@@ -280,6 +328,38 @@ handle_userauth_info_request(
        #ssh_msg_userauth_info_response{num_responses = NumPrompts,
 				       data = Responses}, Ssh)}.
 
+handle_userauth_info_response(#ssh_msg_userauth_info_response{num_responses = 1,
+							      data = <<?UINT32(Sz), Password:Sz/binary>>},
+			      #ssh{opts = Opts0,
+				   user = User} = Ssh) ->
+    NumTriesLeft = proplists:get_value(max_kb_tries, Opts0, 0) - 1,
+    Opts = lists:keydelete(max_kb_tries,1,Opts0),
+    case check_password(User, unicode:characters_to_list(Password), Opts) of
+	true ->
+	    {authorized, User,
+	     ssh_transport:ssh_packet(#ssh_msg_userauth_success{}, Ssh)};
+	false when NumTriesLeft > 0 ->
+	    UserAuthInfoMsg = 
+		(proplists:get_value(kb_userauth_info_msg,Opts))
+		#ssh_msg_userauth_info_request{name = "",
+					       instruction = 
+						   lists:concat(
+						     ["Bad user or password, try again. ",
+						      integer_to_list(NumTriesLeft),
+						      " tries left."])},
+	    {not_authorized, {User, undefined}, 
+	     ssh_transport:ssh_packet(UserAuthInfoMsg,
+				      Ssh#ssh{opts = [{max_kb_tries,NumTriesLeft}|Opts]})};
+	     
+	false ->
+	    {not_authorized, {User, {error,"Bad user or password"}}, 
+	     ssh_transport:ssh_packet(#ssh_msg_userauth_failure{
+					 authentications = "",
+					 partial_success = false}, 
+				      Ssh#ssh{opts = lists:keydelete(kb_userauth_info_msg,1,Opts)}
+				     )}
+    end;
+
 handle_userauth_info_response(#ssh_msg_userauth_info_response{},
 			      _Auth) ->
     throw(#ssh_msg_disconnect{code = ?SSH_DISCONNECT_SERVICE_NOT_AVAILABLE,
diff --git a/lib/ssh/src/ssh_connection_handler.erl b/lib/ssh/src/ssh_connection_handler.erl
index d4bbb0b32e..f751094211 100644
--- a/lib/ssh/src/ssh_connection_handler.erl
+++ b/lib/ssh/src/ssh_connection_handler.erl
@@ -339,13 +339,12 @@ hello({info_line, _Line},#state{role = client, socket = Socket} = State) ->
     inet:setopts(Socket, [{active, once}]),
     {next_state, hello, State};
 
-hello({info_line, _Line},#state{role = server} = State) ->
-    DisconnectMsg =
-	#ssh_msg_disconnect{code =
-				?SSH_DISCONNECT_PROTOCOL_ERROR,
-			    description = "Did not receive expected protocol version exchange",
-			    language = "en"},
-    handle_disconnect(DisconnectMsg, State);
+hello({info_line, _Line},#state{role = server,
+				socket = Socket,
+				transport_cb = Transport } = State) ->
+    %% as openssh
+    Transport:send(Socket, "Protocol mismatch."),
+    {stop, {shutdown,"Protocol mismatch in version exchange."}, State};
 
 hello({version_exchange, Version}, #state{ssh_params = Ssh0,
 					  socket = Socket,
@@ -500,10 +499,21 @@ userauth(#ssh_msg_userauth_info_request{} = Msg,
     {next_state, userauth, next_packet(State#state{ssh_params = Ssh})};
 
 userauth(#ssh_msg_userauth_info_response{} = Msg, 
-	 #state{ssh_params = #ssh{role = server} = Ssh0} = State) ->
-    {ok, {Reply, Ssh}} = ssh_auth:handle_userauth_info_response(Msg, Ssh0),
-    send_msg(Reply, State),
-    {next_state, userauth, next_packet(State#state{ssh_params = Ssh})};
+	 #state{ssh_params = #ssh{role = server,
+				  peer = {_, Address}} = Ssh0,
+		opts = Opts, starter = Pid} = State) ->
+    case ssh_auth:handle_userauth_info_response(Msg, Ssh0) of
+	{authorized, User, {Reply, Ssh}} ->
+	    send_msg(Reply, State),
+	    Pid ! ssh_connected,
+	    connected_fun(User, Address, "keyboard-interactive", Opts),
+	    {next_state, connected, 
+	     next_packet(State#state{auth_user = User, ssh_params = Ssh})};
+	{not_authorized, {User, Reason}, {Reply, Ssh}} ->
+	    retry_fun(User, Address, Reason, Opts),
+	    send_msg(Reply, State),
+	    {next_state, userauth, next_packet(State#state{ssh_params = Ssh})} 
+    end;
 			
 userauth(#ssh_msg_userauth_success{}, #state{ssh_params = #ssh{role = client} = Ssh,
 					     starter = Pid} = State) ->
diff --git a/lib/ssh/src/ssh_transport.erl b/lib/ssh/src/ssh_transport.erl
index 8669be570e..6c0873fd9e 100644
--- a/lib/ssh/src/ssh_transport.erl
+++ b/lib/ssh/src/ssh_transport.erl
@@ -240,20 +240,30 @@ key_exchange_first_msg('diffie-hellman-group-exchange-sha1', Ssh0) ->
 
 handle_kexdh_init(#ssh_msg_kexdh_init{e = E}, Ssh0) ->
     {G, P} = dh_group1(),
-    {Private, Public} = dh_gen_key(G, P, 1024),
-    K = ssh_math:ipow(E, Private, P),
-    Key = get_host_key(Ssh0),
-    H = kex_h(Ssh0, Key, E, Public, K),
-    H_SIG = sign_host_key(Ssh0, Key, H),
-    {SshPacket, Ssh1} = ssh_packet(#ssh_msg_kexdh_reply{public_host_key = Key,
-							f = Public,
-							h_sig = H_SIG
-						       }, Ssh0),
-
-    {ok, SshPacket, Ssh1#ssh{keyex_key = {{Private, Public}, {G, P}},
-			     shared_secret = K,
-			     exchanged_hash = H,
-			     session_id = sid(Ssh1, H)}}.
+    if
+	1=<E, E=<(P-1) ->
+	    {Private, Public} = dh_gen_key(G, P, 1024),
+	    K = ssh_math:ipow(E, Private, P),
+	    Key = get_host_key(Ssh0),
+	    H = kex_h(Ssh0, Key, E, Public, K),
+	    H_SIG = sign_host_key(Ssh0, Key, H),
+	    {SshPacket, Ssh1} = ssh_packet(#ssh_msg_kexdh_reply{public_host_key = Key,
+								f = Public,
+								h_sig = H_SIG
+							       }, Ssh0),
+	    
+	    {ok, SshPacket, Ssh1#ssh{keyex_key = {{Private, Public}, {G, P}},
+				     shared_secret = K,
+				     exchanged_hash = H,
+				     session_id = sid(Ssh1, H)}};
+	true ->
+	    Error = {error,bad_e_from_peer},
+	    Disconnect = #ssh_msg_disconnect{
+			    code = ?SSH_DISCONNECT_KEY_EXCHANGE_FAILED,
+			    description = "Key exchange failed, 'f' out of bounds",
+			    language = "en"},
+	    throw({Error, Disconnect})
+    end.
 
 handle_kex_dh_gex_group(#ssh_msg_kex_dh_gex_group{p = P, g = G}, Ssh0) ->
     {Private, Public} = dh_gen_key(G,P,1024),
@@ -277,7 +287,7 @@ handle_new_keys(#ssh_msg_newkeys{}, Ssh0) ->
 %% %% Select algorithms
 handle_kexdh_reply(#ssh_msg_kexdh_reply{public_host_key = HostKey, f = F,
 					h_sig = H_SIG}, 
-		   #ssh{keyex_key = {{Private, Public}, {_G, P}}} = Ssh0) ->
+		   #ssh{keyex_key = {{Private, Public}, {_G, P}}} = Ssh0) when 1=<F, F=<(P-1)->
     K = ssh_math:ipow(F, Private, P),
     H = kex_h(Ssh0, HostKey, Public, F, K),
 
@@ -293,7 +303,15 @@ handle_kexdh_reply(#ssh_msg_kexdh_reply{public_host_key = HostKey, f = F,
 	      description = "Key exchange failed",
 	      language = "en"},
 	    throw({Error, Disconnect})
-    end.
+    end;
+handle_kexdh_reply(#ssh_msg_kexdh_reply{}, _SSH) ->
+    Error = {error,bad_f_from_peer},
+    Disconnect = #ssh_msg_disconnect{
+		    code = ?SSH_DISCONNECT_KEY_EXCHANGE_FAILED,
+		    description = "Key exchange failed, 'f' out of bounds",
+		    language = "en"},
+    throw({Error, Disconnect}).
+
 
 handle_kex_dh_gex_request(#ssh_msg_kex_dh_gex_request{min = _Min,
 						      n   = _NBits,
@@ -519,10 +537,15 @@ alg_final(SSH0) ->
     {ok,SSH6} = decompress_final(SSH5),
     SSH6.
 
-select_all(CL, SL) ->
+select_all(CL, SL) when length(CL) + length(SL) < 50 ->
     A = CL -- SL,  %% algortihms only used by client
     %% algorithms used by client and server (client pref)
-    lists:map(fun(ALG) -> list_to_atom(ALG) end, (CL -- A)).
+    lists:map(fun(ALG) -> list_to_atom(ALG) end, (CL -- A));
+select_all(_CL, _SL) ->
+    throw(#ssh_msg_disconnect{code = ?SSH_DISCONNECT_PROTOCOL_ERROR,
+			      description = "Too many algorithms", 
+			      language = "en"}).
+
 
 select([], []) ->
     none;