@@ -52,6 +52,11 @@ Script Order of Execution
Executed in ``--mode server`` mode on new client connections, when the
client is still untrusted.
+#. ``--client-crresponse``
+
+ Execute in ``--mode server`` whenever a client sends a
+ :code:`CR_RESPONSE` message
+
SCRIPT HOOKS
------------
@@ -72,7 +77,7 @@ SCRIPT HOOKS
double-quoted and/or escaped using a backslash, and should be separated
by one or more spaces.
- If ``method`` is set to :code:`via-env`, OpenVPN will call ``script``
+ If ``method`` is set to :code:`via-env`, OpenVPN will call ``cmd``
with the environmental variables :code:`username` and :code:`password`
set to the username/password strings provided by the client. *Beware*
that this method is insecure on some platforms which make the environment
@@ -80,7 +85,7 @@ SCRIPT HOOKS
If ``method`` is set to :code:`via-file`, OpenVPN will write the username
and password to the first two lines of a temporary file. The filename
- will be passed as an argument to ``script``, and the file will be
+ will be passed as an argument to ``cmd``, and the file will be
automatically deleted by OpenVPN after the script returns. The location
of the temporary file is controlled by the ``--tmp-dir`` option, and
will default to the current directory if unspecified. For security,
@@ -123,6 +128,25 @@ SCRIPT HOOKS
For a sample script that performs PAM authentication, see
:code:`sample-scripts/auth-pam.pl` in the OpenVPN source distribution.
+--client-crresponse
+ Executed when the client sends a text based challenge response.
+
+ Valid syntax:
+ ::
+
+ client-crresponse cmd
+
+ OpenVPN will write the response of the client into a temporary file.
+ The filename will be passed as an argument to ``cmd``, and the file will be
+ automatically deleted by OpenVPN after the script returns.
+
+ The response is passed as is from the client. The script needs to check
+ itself if the input is valid, e.g. if the input is valid base64 encoding.
+
+ The script can either directly write the result of the verification to
+ :code:`auth_control_file or further defer it. See ``--auth-user-pass-verify``
+ for details.
+
--client-connect cmd
Run command ``cmd`` on client connection.
@@ -83,6 +83,10 @@ extern "C" {
* FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_CLIENT_CONNECT_V2
* FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_LEARN_ADDRESS
*
+ * The OPENVPN_PLUGIN_CLIENT_CRRESPONSE function is called when the client sends
+ * the CR_RESPONSE message, this is *typically* after OPENVPN_PLUGIN_TLS_FINAL
+ * but may also occur much later.
+ *
* [Client session ensues]
*
* For each "TLS soft reset", according to reneg-sec option (or similar):
@@ -128,7 +132,8 @@ extern "C" {
#define OPENVPN_PLUGIN_ROUTE_PREDOWN 12
#define OPENVPN_PLUGIN_CLIENT_CONNECT_DEFER 13
#define OPENVPN_PLUGIN_CLIENT_CONNECT_DEFER_V2 14
-#define OPENVPN_PLUGIN_N 15
+#define OPENVPN_PLUGIN_CLIENT_CRRESPONSE 15
+#define OPENVPN_PLUGIN_N 16
/*
* Build a mask out of a set of plug-in types.
@@ -3033,6 +3033,7 @@ do_init_crypto_tls(struct context *c, const unsigned int flags)
to.auth_user_pass_verify_script = options->auth_user_pass_verify_script;
to.auth_user_pass_verify_script_via_file = options->auth_user_pass_verify_script_via_file;
+ to.client_crresponse_script = options->client_crresponse_script;
to.tmp_dir = options->tmp_dir;
if (options->ccd_exclusive)
{
@@ -1525,6 +1525,7 @@ show_p2mp_parms(const struct options *o)
SHOW_STR(client_connect_script);
SHOW_STR(learn_address_script);
SHOW_STR(client_disconnect_script);
+ SHOW_STR(client_crresponse_script);
SHOW_STR(client_config_dir);
SHOW_BOOL(ccd_exclusive);
SHOW_STR(tmp_dir);
@@ -2684,6 +2685,10 @@ options_postprocess_verify_ce(const struct options *options,
{
msg(M_USAGE, "--client-connect requires --mode server");
}
+ if (options->client_crresponse_script)
+ {
+ msg(M_USAGE, "--client-crresponse requires --mode server");
+ }
if (options->client_disconnect_script)
{
msg(M_USAGE, "--client-disconnect requires --mode server");
@@ -7447,6 +7452,16 @@ add_option(struct options *options,
set_user_script(options, &options->client_connect_script,
p[1], "client-connect", true);
}
+ else if (streq(p[0], "client-crresponse") && p[1])
+ {
+ VERIFY_PERMISSION(OPT_P_SCRIPT);
+ if (!no_more_than_n_args(msglevel, p, 2, NM_QUOTE_HINT))
+ {
+ goto err;
+ }
+ set_user_script(options, &options->client_crresponse_script,
+ p[1], "client-crresponse", true);
+ }
else if (streq(p[0], "client-disconnect") && p[1])
{
VERIFY_PERMISSION(OPT_P_SCRIPT);
@@ -473,6 +473,7 @@ struct options
const char *client_connect_script;
const char *client_disconnect_script;
const char *learn_address_script;
+ const char *client_crresponse_script;
const char *client_config_dir;
bool ccd_exclusive;
bool disable;
@@ -102,7 +102,7 @@ plugin_type_name(const int type)
return "PLUGIN_CLIENT_CONNECT";
case OPENVPN_PLUGIN_CLIENT_CONNECT_V2:
- return "PLUGIN_CLIENT_CONNECT";
+ return "PLUGIN_CLIENT_CONNECT_V2";
case OPENVPN_PLUGIN_CLIENT_CONNECT_DEFER:
return "PLUGIN_CLIENT_CONNECT_DEFER";
@@ -122,6 +122,9 @@ plugin_type_name(const int type)
case OPENVPN_PLUGIN_ROUTE_PREDOWN:
return "PLUGIN_ROUTE_PREDOWN";
+ case OPENVPN_PLUGIN_CLIENT_CRRESPONSE:
+ return "PLUGIN_CRRESPONSE";
+
default:
return "PLUGIN_???";
}
@@ -229,6 +229,10 @@ receive_cr_response(struct context *c, const struct buffer *buffer)
management_notify_client_cr_response(key_id, mda, es, m);
#endif
+#if ENABLE_PLUGIN
+ verify_crresponse_plugin(c->c2.tls_multi, m);
+#endif
+ verify_crresponse_script(c->c2.tls_multi, m);
msg(D_PUSH, "CR response was sent by client ('%s')", m);
}
@@ -362,6 +362,7 @@ struct tls_options
/* used for username/password authentication */
const char *auth_user_pass_verify_script;
+ const char *client_crresponse_script;
bool auth_user_pass_verify_script_via_file;
const char *tmp_dir;
const char *auth_user_pass_file;
@@ -1352,6 +1352,73 @@ done:
return retval;
}
+#ifdef ENABLE_PLUGIN
+void
+verify_crresponse_plugin(struct tls_multi *multi, const char *cr_response)
+{
+ struct tls_session *session = &multi->session[TM_ACTIVE];
+ setenv_str(session->opt->es, "crresponse", cr_response);
+
+ plugin_call(session->opt->plugins, OPENVPN_PLUGIN_CLIENT_CRRESPONSE, NULL,
+ NULL, session->opt->es);
+
+ setenv_del(session->opt->es, "crresponse");
+}
+#endif
+
+void
+verify_crresponse_script(struct tls_multi *multi, const char *cr_response)
+{
+
+ struct tls_session *session = &multi->session[TM_ACTIVE];
+
+ if (!session->opt->client_crresponse_script)
+ {
+ return;
+ }
+ struct argv argv = argv_new();
+ struct gc_arena gc = gc_new();
+
+ setenv_str(session->opt->es, "script_type", "client-crresponse");
+
+ /* Since cr response might be sensitive, like a stupid way to query
+ * a password via 2FA, we pass it via file instead environment */
+ const char *tmp_file = platform_create_temp_file(session->opt->tmp_dir, "cr", &gc);
+ static const char *openerrmsg = "TLS CR Response Error: could not write "
+ "crtext challenge response to file: %s";
+
+ if (tmp_file)
+ {
+ struct status_output *so = status_open(tmp_file, 0, -1, NULL,
+ STATUS_OUTPUT_WRITE);
+ status_printf(so, "%s", cr_response);
+ if (!status_close(so))
+ {
+ msg(D_TLS_ERRORS, openerrmsg, tmp_file);
+ tls_deauthenticate(multi);
+ goto done;
+ }
+ }
+ else
+ {
+ msg(D_TLS_ERRORS, openerrmsg, "creating file failed");
+ tls_deauthenticate(multi);
+ goto done;
+ }
+
+ argv_parse_cmd(&argv, session->opt->client_crresponse_script);
+ argv_printf_cat(&argv, "%s", tmp_file);
+
+
+ if (!openvpn_run_script(&argv, session->opt->es, 0, "--client-crresponse"))
+ {
+ tls_deauthenticate(multi);
+ }
+done:
+ argv_free(&argv);
+ gc_free(&gc);
+}
+
/*
* Verify the username and password using a plugin
*/
@@ -177,6 +177,29 @@ bool cert_hash_compare(const struct cert_hash_set *chs1, const struct cert_hash_
void verify_user_pass(struct user_pass *up, struct tls_multi *multi,
struct tls_session *session);
+
+
+/**
+ * Runs the --client-crresponse script if one is defined.
+ *
+ * As with the management interface the script is stateless in the sense that
+ * it does not directly participate in the authentication but rather should set
+ * the files for the deferred auth like the management commands.
+ *
+ */
+void
+verify_crresponse_script(struct tls_multi *multi, const char *cr_response);
+
+/**
+ * Call the plugin OPENVPN_PLUGIN_CLIENT_CRRESPONSE.
+ *
+ * As with the management interface calling the plugin is stateless in the sense
+ * that it does not directly participate in the authentication but rather
+ * should set the files for the deferred auth like the management commands.
+ */
+void
+verify_crresponse_plugin(struct tls_multi *multi, const char *cr_response);
+
/**
* Perform final authentication checks, including locking of the cn, the allowed
* certificate hashes, and whether a client config entry exists in the
This is allows scripts and pluginsto parse/react to a CR_RESPONSE message Patch V2: doc fixes, do not put script under ENABLE_PLUGIN Patch V3: rebase Patch V4: fix else branch of the verify_crresponse_script function Patch V5: unify message when unable to create/write crresponse file Signed-off-by: Arne Schwabe <arne@rfc2549.org> --- doc/man-sections/script-options.rst | 28 +++++++++++- include/openvpn-plugin.h.in | 7 ++- src/openvpn/init.c | 1 + src/openvpn/options.c | 15 +++++++ src/openvpn/options.h | 1 + src/openvpn/plugin.c | 5 ++- src/openvpn/push.c | 4 ++ src/openvpn/ssl_common.h | 1 + src/openvpn/ssl_verify.c | 67 +++++++++++++++++++++++++++++ src/openvpn/ssl_verify.h | 23 ++++++++++ 10 files changed, 148 insertions(+), 4 deletions(-)