EAP-TTLS: Add support for deriving EMSK

This extends EAP-TTLS server and peer implementations to support EMSK
derivation per RFC 5281.

Signed-off-by: Jouni Malinen <j@w1.fi>

diff --git a/src/eap_peer/eap_ttls.c b/src/eap_peer/eap_ttls.c
index 771da58..a8f4a2d 100644 (file)
--- a/src/eap_peer/eap_ttls.c
+++ b/src/eap_peer/eap_ttls.c
@@ -136,7 +136,7 @@ static void eap_ttls_phase2_eap_deinit(struct eap_sm *sm,
 static void eap_ttls_free_key(struct eap_ttls_data *data)
 {
        if (data->key_data) {
-               bin_clear_free(data->key_data, EAP_TLS_KEY_LEN);
+               bin_clear_free(data->key_data, EAP_TLS_KEY_LEN + EAP_EMSK_LEN);
                data->key_data = NULL;
        }
 }
@@ -225,7 +225,8 @@ static int eap_ttls_v0_derive_key(struct eap_sm *sm,
        eap_ttls_free_key(data);
        data->key_data = eap_peer_tls_derive_key(sm, &data->ssl,
                                                 "ttls keying material",
-                                                EAP_TLS_KEY_LEN);
+                                                EAP_TLS_KEY_LEN +
+                                                EAP_EMSK_LEN);
        if (!data->key_data) {
                wpa_printf(MSG_INFO, "EAP-TTLS: Failed to derive key");
                return -1;
@@ -233,6 +234,9 @@ static int eap_ttls_v0_derive_key(struct eap_sm *sm,
 
        wpa_hexdump_key(MSG_DEBUG, "EAP-TTLS: Derived key",
                        data->key_data, EAP_TLS_KEY_LEN);
+       wpa_hexdump_key(MSG_DEBUG, "EAP-TTLS: Derived EMSK",
+                       data->key_data + EAP_TLS_KEY_LEN,
+                       EAP_EMSK_LEN);
 
        os_free(data->session_id);
        data->session_id = eap_peer_tls_derive_session_id(sm, &data->ssl,
@@ -1645,6 +1649,25 @@ static u8 * eap_ttls_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
 }
 
 
+static u8 * eap_ttls_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
+{
+       struct eap_ttls_data *data = priv;
+       u8 *key;
+
+       if (data->key_data == NULL)
+               return NULL;
+
+       key = os_malloc(EAP_EMSK_LEN);
+       if (key == NULL)
+               return NULL;
+
+       *len = EAP_EMSK_LEN;
+       os_memcpy(key, data->key_data + EAP_TLS_KEY_LEN, EAP_EMSK_LEN);
+
+       return key;
+}
+
+
 int eap_peer_ttls_register(void)
 {
        struct eap_method *eap;
@@ -1665,6 +1688,7 @@ int eap_peer_ttls_register(void)
        eap->has_reauth_data = eap_ttls_has_reauth_data;
        eap->deinit_for_reauth = eap_ttls_deinit_for_reauth;
        eap->init_for_reauth = eap_ttls_init_for_reauth;
+       eap->get_emsk = eap_ttls_get_emsk;
 
        ret = eap_peer_method_register(eap);
        if (ret)

diff --git a/src/eap_server/eap_server_ttls.c b/src/eap_server/eap_server_ttls.c
index f2b0e55..7f662d9 100644 (file)
--- a/src/eap_server/eap_server_ttls.c
+++ b/src/eap_server/eap_server_ttls.c
@@ -1193,6 +1193,38 @@ static u8 * eap_ttls_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
 }
 
 
+static u8 * eap_ttls_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
+{
+       struct eap_ttls_data *data = priv;
+       u8 *eapKeyData, *emsk;
+
+       if (data->state != SUCCESS)
+               return NULL;
+
+       eapKeyData = eap_server_tls_derive_key(sm, &data->ssl,
+                                              "ttls keying material",
+                                              EAP_TLS_KEY_LEN + EAP_EMSK_LEN);
+       if (eapKeyData) {
+               emsk = os_malloc(EAP_EMSK_LEN);
+               if (emsk)
+                       os_memcpy(emsk, eapKeyData + EAP_TLS_KEY_LEN,
+                                 EAP_EMSK_LEN);
+               bin_clear_free(eapKeyData, EAP_TLS_KEY_LEN + EAP_EMSK_LEN);
+       } else
+               emsk = NULL;
+
+       if (emsk) {
+               *len = EAP_EMSK_LEN;
+               wpa_hexdump(MSG_DEBUG, "EAP-TTLS: Derived EMSK",
+                           emsk, EAP_EMSK_LEN);
+       } else {
+               wpa_printf(MSG_DEBUG, "EAP-TTLS: Failed to derive EMSK");
+       }
+
+       return emsk;
+}
+
+
 int eap_server_ttls_register(void)
 {
        struct eap_method *eap;
@@ -1212,6 +1244,7 @@ int eap_server_ttls_register(void)
        eap->getKey = eap_ttls_getKey;
        eap->isSuccess = eap_ttls_isSuccess;
        eap->getSessionId = eap_ttls_get_session_id;
+       eap->get_emsk = eap_ttls_get_emsk;
 
        ret = eap_server_method_register(eap);
        if (ret)