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EAP peer: External server certificate chain validation

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This adds support for optional functionality to validate server
certificate chain in TLS-based EAP methods in an external program.
wpa_supplicant control interface is used to indicate when such
validation is needed and what the result of the external validation is.

This external validation can extend or replace the internal validation.
When ca_cert or ca_path parameter is set, the internal validation is
used. If these parameters are omitted, only the external validation is
used. It needs to be understood that leaving those parameters out will
disable most of the validation steps done with the TLS library and that
configuration is not really recommend.

By default, the external validation is not used. It can be enabled by
addingtls_ext_cert_check=1 into the network profile phase1 parameter.
When enabled, external validation is required through the CTRL-REQ/RSP
mechanism similarly to other EAP authentication parameters through the
control interface.

The request to perform external validation is indicated by the following
event:
CTRL-REQ-EXT_CERT_CHECK-<id>:External server certificate validation needed for SSID <ssid>

Before that event, the server certificate chain is provided with the
CTRL-EVENT-EAP-PEER-CERT events that include the cert=<hexdump>
parameter. depth=# indicates which certificate is in question (0 for the
server certificate, 1 for its issues, and so on).

The result of the external validation is provided with the following
command:
CTRL-RSP-EXT_CERT_CHECK-<id>:<good|bad>

It should be noted that this is currently enabled only for OpenSSL (and
BoringSSL/LibreSSL). Due to the constraints in the library API, the
validation result from external processing cannot be reported cleanly
with TLS alert. In other words, if the external validation reject the
server certificate chain, the pending TLS handshake is terminated
without sending more messages to the server.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2015-12-12 18:16:54 +02:00
parent be90370bd5
commit 3c108b7573
16 changed files with 245 additions and 12 deletions
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44
src/eap_peer/eap_peap.c
View file

@ -1,6 +1,6 @@
/*
* EAP peer method: EAP-PEAP (draft-josefsson-pppext-eap-tls-eap-10.txt)
* Copyright (c) 2004-2008, Jouni Malinen <j@w1.fi>
* Copyright (c) 2004-2015, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
@ -59,6 +59,7 @@ struct eap_peap_data {
size_t id_len;
struct wpabuf *pending_phase2_req;
struct wpabuf *pending_resp;
enum { NO_BINDING, OPTIONAL_BINDING, REQUIRE_BINDING } crypto_binding;
int crypto_binding_used;
u8 binding_nonce[32];
@ -191,6 +192,7 @@ static void eap_peap_deinit(struct eap_sm *sm, void *priv)
eap_peap_free_key(data);
os_free(data->session_id);
wpabuf_free(data->pending_phase2_req);
wpabuf_free(data->pending_resp);
os_free(data);
}
@ -1006,6 +1008,34 @@ static struct wpabuf * eap_peap_process(struct eap_sm *sm, void *priv,
!data->resuming) {
res = eap_peap_decrypt(sm, data, ret, req, &msg, &resp);
} else {
if (sm->waiting_ext_cert_check && data->pending_resp) {
struct eap_peer_config *config = eap_get_config(sm);
if (config->pending_ext_cert_check ==
EXT_CERT_CHECK_GOOD) {
wpa_printf(MSG_DEBUG,
"EAP-PEAP: External certificate check succeeded - continue handshake");
resp = data->pending_resp;
data->pending_resp = NULL;
sm->waiting_ext_cert_check = 0;
return resp;
}
if (config->pending_ext_cert_check ==
EXT_CERT_CHECK_BAD) {
wpa_printf(MSG_DEBUG,
"EAP-PEAP: External certificate check failed - force authentication failure");
ret->methodState = METHOD_DONE;
ret->decision = DECISION_FAIL;
sm->waiting_ext_cert_check = 0;
return NULL;
}
wpa_printf(MSG_DEBUG,
"EAP-PEAP: Continuing to wait external server certificate validation");
return NULL;
}
res = eap_peer_tls_process_helper(sm, &data->ssl,
EAP_TYPE_PEAP,
data->peap_version, id, &msg,
@ -1018,6 +1048,16 @@ static struct wpabuf * eap_peap_process(struct eap_sm *sm, void *priv,
ret->decision = DECISION_FAIL;
return resp;
}
if (sm->waiting_ext_cert_check) {
wpa_printf(MSG_DEBUG,
"EAP-PEAP: Waiting external server certificate validation");
wpabuf_free(data->pending_resp);
data->pending_resp = resp;
return NULL;
}
if (tls_connection_established(sm->ssl_ctx, data->ssl.conn)) {
char *label;
wpa_printf(MSG_DEBUG,
@ -1123,6 +1163,8 @@ static void eap_peap_deinit_for_reauth(struct eap_sm *sm, void *priv)
struct eap_peap_data *data = priv;
wpabuf_free(data->pending_phase2_req);
data->pending_phase2_req = NULL;
wpabuf_free(data->pending_resp);
data->pending_resp = NULL;
data->crypto_binding_used = 0;
}