Skip to content

michal/ssh/prevent-duplicate-subsystem-spawns-on-same-channel/OTP-20284 #11437

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
Mikaka27 wants to merge 1 commit into
base: maint
Choose a base branch
from
+91 −22
Open

michal/ssh/prevent-duplicate-subsystem-spawns-on-same-channel/OTP-20284 #11437

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
36 changes: 23 additions & 13 deletions lib/ssh/src/ssh_connection.erl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1126,21 +1126,31 @@ handle_msg(#ssh_msg_channel_request{recipient_channel = ChannelId,
binary_to_list(SigName)});

handle_msg(#ssh_msg_channel_request{recipient_channel = ChannelId,
request_type = "subsystem",
want_reply = WantReply,
data = Data},
#connection{channel_cache = Cache} = Connection, server, _SSH) ->
request_type = "subsystem",
want_reply = WantReply,
data = Data},
#connection{channel_cache = Cache} = Connection, server, _SSH) ->
<<?DEC_BIN(SsName,_SsLen)>> = Data,
#channel{remote_id=RemoteId} = Channel =
ssh_client_channel:cache_lookup(Cache, ChannelId),
#channel{remote_id=RemoteId,user=User} = Channel =
ssh_client_channel:cache_lookup(Cache, ChannelId),
Reply =
case start_subsystem(SsName, Connection, Channel,
{subsystem, ChannelId, WantReply, binary_to_list(SsName)}) of
{ok, Pid} ->
erlang:monitor(process, Pid),
ssh_client_channel:cache_update(Cache, Channel#channel{user=Pid}),
channel_success_msg(RemoteId);
{error,_Error} ->
case User of
undefined ->
case start_subsystem(SsName, Connection, Channel,
{subsystem, ChannelId, WantReply, binary_to_list(SsName)}) of
{ok, Pid} ->
erlang:monitor(process, Pid),
ssh_client_channel:cache_update(Cache, Channel#channel{user=Pid}),
channel_success_msg(RemoteId);
{error,_Error} ->
channel_failure_msg(RemoteId)
end;
_ ->
%% If shell, exec or any subsystem is active on the channel, starting another
%% subsystem must fail. See RFC 4254 6.5
%% In our case 'env' (RFC 4254 6.6) and 'pty-req' (RFC 4254 6.2) also start cli
%% handler, so if any of them are started, trying to start any subsystem
%% will also fail here.
channel_failure_msg(RemoteId)
end,
{[{connection_reply,Reply}], Connection};
Expand Down
77 changes: 68 additions & 9 deletions lib/ssh/test/ssh_connection_SUITE.erl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -108,6 +108,11 @@
start_shell_sock_daemon_exec_multi/1,
start_shell_sock_exec_fun/1,
start_subsystem_on_closed_channel/1,
start_subsystem_on_channel_with_subsystem/1,
start_subsystem_on_channel_with_pty_req/1,
start_subsystem_on_channel_with_shell/1,
start_subsystem_on_channel_with_exec/1,
start_subsystem_on_channel_with_env/1,
stop_listener/1,
trap_exit_connect/1,
trap_exit_daemon/1,
Expand Down Expand Up @@ -187,6 +192,11 @@ all() ->
stop_listener,
no_sensitive_leak,
start_subsystem_on_closed_channel,
start_subsystem_on_channel_with_subsystem,
start_subsystem_on_channel_with_pty_req,
start_subsystem_on_channel_with_shell,
start_subsystem_on_channel_with_exec,
start_subsystem_on_channel_with_env,
max_channels_option,
handler_down_before_open,
replace_options_enable_services
Expand Down Expand Up @@ -1761,23 +1771,29 @@ no_sensitive_leak(Config) ->
{_, _, 0} -> ok;
{_, _, Nt0} -> ct:fail("Leak in ~p cases!", [Nt0])
end.

start_subsystem_on_closed_channel(Config) ->

start_server_and_connect_client(Config) ->
start_server_and_connect_client(Config, []).
start_server_and_connect_client(Config, DaemonOpts) ->
PrivDir = proplists:get_value(priv_dir, Config),
UserDir = filename:join(PrivDir, nopubkey), % to make sure we don't use public-key-auth
file:make_dir(UserDir),
SysDir = proplists:get_value(data_dir, Config),
{Pid, Host, Port} = ssh_test_lib:daemon([{system_dir, SysDir},
{user_dir, UserDir},
{password, "morot"},
{subsystems, [{"echo_n", {ssh_echo_server, [4000000]}}]}]),
{user_dir, UserDir},
{password, "morot"},
{subsystems, [{"echo_n", {ssh_echo_server, [4000000]}}]}] ++ DaemonOpts),

ConnectionRef = ssh_test_lib:connect(Host, Port, [{silently_accept_hosts, true},
{user, "foo"},
{password, "morot"},
{user_interaction, false},
{user_dir, UserDir}]),
{user, "foo"},
{password, "morot"},
{user_interaction, false},
{user_dir, UserDir}]),

{ConnectionRef, Pid}.

start_subsystem_on_closed_channel(Config) ->
{ConnectionRef, Pid} = start_server_and_connect_client(Config),

{ok, ChannelId1} = ssh_connection:session_channel(ConnectionRef, infinity),
ok = ssh_connection:close(ConnectionRef, ChannelId1),
Expand All @@ -1798,6 +1814,49 @@ start_subsystem_on_closed_channel(Config) ->
ssh:close(ConnectionRef),
ssh:stop_daemon(Pid).

start_server_connect_client_and_get_channel(Config) ->
start_server_connect_client_and_get_channel(Config, []).
start_server_connect_client_and_get_channel(Config, DaemonOpts) ->
{ConnectionRef, Pid} = start_server_and_connect_client(Config, DaemonOpts),
{ok, ChannelId} = ssh_connection:session_channel(ConnectionRef, infinity),
{ConnectionRef, ChannelId, Pid}.

start_subsystem_on_channel_with_subsystem(Config) ->
{ConnectionRef, ChannelId, Pid} = start_server_connect_client_and_get_channel(Config),
success = ssh_connection:subsystem(ConnectionRef, ChannelId, "echo_n", 5000),
check_subsystem_start_failure(ConnectionRef, ChannelId, Pid).

start_subsystem_on_channel_with_pty_req(Config) ->
DaemonOpts = [{shell, fun(_U, _P) -> spawn(fun() -> timer:sleep(infinity) end) end}],
{ConnectionRef, ChannelId, Pid} = start_server_connect_client_and_get_channel(Config, DaemonOpts),
success = ssh_connection:ptty_alloc(ConnectionRef, ChannelId, []),
check_subsystem_start_failure(ConnectionRef, ChannelId, Pid).

start_subsystem_on_channel_with_shell(Config) ->
DaemonOpts = [{shell, fun(_U, _P) -> spawn(fun() -> timer:sleep(infinity) end) end}],
{ConnectionRef, ChannelId, Pid} = start_server_connect_client_and_get_channel(Config, DaemonOpts),
ok = ssh_connection:shell(ConnectionRef, ChannelId),
check_subsystem_start_failure(ConnectionRef, ChannelId, Pid).

start_subsystem_on_channel_with_exec(Config) ->
DaemonOpts = [{exec, fun ssh_exec_echo/1}],
{ConnectionRef, ChannelId, Pid} = start_server_connect_client_and_get_channel(Config, DaemonOpts),
success = ssh_connection:exec(ConnectionRef, ChannelId, "testing1.\n", 5000),
check_subsystem_start_failure(ConnectionRef, ChannelId, Pid).

start_subsystem_on_channel_with_env(Config) ->
DaemonOpts = [{shell, fun(_U, _P) -> spawn(fun() -> timer:sleep(infinity) end) end}],
{ConnectionRef, ChannelId, Pid} = start_server_connect_client_and_get_channel(Config, DaemonOpts),
%% setenv is not implemented, and will return a failure, but cli handler will be started anyway
failure = ssh_connection:setenv(ConnectionRef, ChannelId, "ENV_TEST", "VALUE", infinity),
check_subsystem_start_failure(ConnectionRef, ChannelId, Pid).

check_subsystem_start_failure(ConnectionRef, ChannelId, Pid) ->
failure = ssh_connection:subsystem(ConnectionRef, ChannelId, "echo_n", 5000),

ssh:close(ConnectionRef),
ssh:stop_daemon(Pid).

%%--------------------------------------------------------------------
max_channels_option(Config) when is_list(Config) ->
PrivDir = proplists:get_value(priv_dir, Config),
Expand Down
Loading