ssh: avoid protocol error on userauth banner

SSH servers can send userauth banners at any time during authentication
and the erlang SSH client only accepted userauth banners in some limited
circumstances.

Closes #9065

lib/ssh/src/ssh_fsm_userauth_client.erl

@@ -105,7 +105,10 @@ handle_event(internal, #ssh_msg_userauth_failure{authentications = Methods}, Sta
     end;
 
 %%---- banner to client
-handle_event(internal, #ssh_msg_userauth_banner{message = Msg}, {userauth,client}, D) ->
+handle_event(internal, #ssh_msg_userauth_banner{message = Msg}, {S,client}, D)
+  when S == userauth; S == userauth_keyboard_interactive;
+       S == userauth_keyboard_interactive_extra;
+       S == userauth_keyboard_interactive_info_response ->
     case D#data.ssh_params#ssh.userauth_quiet_mode of
 	false -> io:format("~s", [Msg]);
 	true -> ok

lib/ssh/test/ssh_protocol_SUITE.erl

@@ -47,6 +47,7 @@
          bad_service_name_then_correct/1,
          bad_very_long_service_name/1,
          client_handles_keyboard_interactive_0_pwds/1,
+         client_handles_banner_keyboard_interactive/1,
          client_info_line/1,
          do_gex_client_init/3,
          do_gex_client_init_old/3,
@@ -144,7 +145,8 @@ groups() ->
 			     empty_service_name,
 			     bad_service_name_then_correct
 			    ]},
-     {authentication, [], [client_handles_keyboard_interactive_0_pwds
+     {authentication, [], [client_handles_keyboard_interactive_0_pwds,
+                           client_handles_banner_keyboard_interactive
 			  ]},
      {ext_info, [], [no_ext_info_s1,
                      no_ext_info_s2,
@@ -682,7 +684,82 @@ client_handles_keyboard_interactive_0_pwds(Config) ->
                                                 ]}]
 			).
 
+%%%--------------------------------------------------------------------
+%%% SSH_MSG_USERAUTH_BANNER can be sent at any time during user auth.
+%%% The following test mimics a SSH server implementation that sends the banner
+%%% immediately before sending SSH_MSG_USERAUTH_SUCCESS.
+client_handles_banner_keyboard_interactive(Config) ->
+    {User,_Pwd} = server_user_password(Config),
+
+    %% Create a listening socket as server socket:
+    {ok,InitialState} = ssh_trpt_test_lib:exec(listen),
+    HostPort = ssh_trpt_test_lib:server_host_port(InitialState),
+
+    %% Start a process handling one connection on the server side:
+    spawn_link(
+      fun() ->
+	      {ok,_} =
+		  ssh_trpt_test_lib:exec(
+		    [{set_options, [print_ops, print_messages]},
+		     {accept, [{system_dir, system_dir(Config)},
+			       {user_dir, user_dir(Config)}]},
+		     receive_hello,
+		     {send, hello},
 
+		     {send, ssh_msg_kexinit},
+		     {match, #ssh_msg_kexinit{_='_'}, receive_msg},
+
+		     {match, #ssh_msg_kexdh_init{_='_'}, receive_msg},
+		     {send, ssh_msg_kexdh_reply},
+
+		     {send, #ssh_msg_newkeys{}},
+		     {match,  #ssh_msg_newkeys{_='_'}, receive_msg},
+
+		     {match, #ssh_msg_service_request{name="ssh-userauth"}, receive_msg},
+		     {send, #ssh_msg_service_accept{name="ssh-userauth"}},
+
+		     {match, #ssh_msg_userauth_request{service="ssh-connection",
+						       method="none",
+						       user=User,
+						       _='_'}, receive_msg},
+		     {send, #ssh_msg_userauth_failure{authentications = "keyboard-interactive",
+						      partial_success = false}},
+
+		     {match, #ssh_msg_userauth_request{service="ssh-connection",
+						       method="keyboard-interactive",
+						       user=User,
+						       _='_'}, receive_msg},
+		     {send, #ssh_msg_userauth_info_request{name = "",
+							   instruction = "",
+							   language_tag = "",
+							   num_prompts = 1,
+							   data = <<0,0,0,10,80,97,115,115,119,111,114,100,58,32,0>>
+							  }},
+		     {match, #ssh_msg_userauth_info_response{num_responses = 1,
+							     _='_'}, receive_msg},
+		     {send, #ssh_msg_userauth_info_request{name = "",
+							   instruction = "",
+							   language_tag = "",
+							   num_prompts = 0,
+							   data = <<>>
+							  }},
+		     {match, #ssh_msg_userauth_info_response{num_responses = 0,
+							     data = <<>>,
+							     _='_'}, receive_msg},
+                     {send, #ssh_msg_userauth_banner{message = "Banner\n"}},
+		     {send, #ssh_msg_userauth_success{}},
+		     close_socket,
+		     print_state
+		    ],
+		    InitialState)
+      end),
+
+    %% and finally connect to it with a regular Erlang SSH client:
+    {ok,_} = std_connect(HostPort, Config,
+			 [{preferred_algorithms,[{kex,[?DEFAULT_KEX]},
+                                                 {cipher,?DEFAULT_CIPHERS}
+                                                ]}]
+			).
 
 %%%--------------------------------------------------------------------
 client_info_line(Config) ->