EAP-PAX: Derive EAP Session-Id

This adds EAP-PAX server and peer method functions for deriving
Session-Id from Method-Id per RFC 4746 and RFC 5247.

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

src/eap_common/eap_pax_common.c

@@ -121,10 +121,11 @@ int eap_pax_mac(u8 mac_id, const u8 *key, size_t key_len,
  * @mk: Buffer for the derived Master Key
  * @ck: Buffer for the derived Confirmation Key
  * @ick: Buffer for the derived Integrity Check Key
+ * @mid: Buffer for the derived Method ID
  * Returns: 0 on success, -1 on failure
  */
 int eap_pax_initial_key_derivation(u8 mac_id, const u8 *ak, const u8 *e,
-				   u8 *mk, u8 *ck, u8 *ick)
+				   u8 *mk, u8 *ck, u8 *ick, u8 *mid)
 {
 	wpa_printf(MSG_DEBUG, "EAP-PAX: initial key derivation");
 	if (eap_pax_kdf(mac_id, ak, EAP_PAX_AK_LEN, "Master Key",
@@ -132,13 +133,16 @@ int eap_pax_initial_key_derivation(u8 mac_id, const u8 *ak, const u8 *e,
 	    eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Confirmation Key",
 			e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_CK_LEN, ck) ||
 	    eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Integrity Check Key",
-			e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_ICK_LEN, ick))
+			e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_ICK_LEN, ick) ||
+	    eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Method ID",
+			e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_MID_LEN, mid))
 		return -1;
 
 	wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: AK", ak, EAP_PAX_AK_LEN);
 	wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: MK", mk, EAP_PAX_MK_LEN);
 	wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: CK", ck, EAP_PAX_CK_LEN);
 	wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: ICK", ick, EAP_PAX_ICK_LEN);
+	wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: MID", mid, EAP_PAX_MID_LEN);
 
 	return 0;
 }

src/eap_common/eap_pax_common.h

@@ -74,6 +74,7 @@ enum {
 #define EAP_PAX_MK_LEN 16
 #define EAP_PAX_CK_LEN 16
 #define EAP_PAX_ICK_LEN 16
+#define EAP_PAX_MID_LEN 16
 
 
 int eap_pax_kdf(u8 mac_id, const u8 *key, size_t key_len,
@@ -86,6 +87,6 @@ int eap_pax_mac(u8 mac_id, const u8 *key, size_t key_len,
 		const u8 *data3, size_t data3_len,
 		u8 *mac);
 int eap_pax_initial_key_derivation(u8 mac_id, const u8 *ak, const u8 *e,
-				   u8 *mk, u8 *ck, u8 *ick);
+				   u8 *mk, u8 *ck, u8 *ick, u8 *mid);
 
 #endif /* EAP_PAX_COMMON_H */

src/eap_peer/eap_pax.c

@@ -38,6 +38,7 @@ struct eap_pax_data {
 	u8 mk[EAP_PAX_MK_LEN];
 	u8 ck[EAP_PAX_CK_LEN];
 	u8 ick[EAP_PAX_ICK_LEN];
+	u8 mid[EAP_PAX_MID_LEN];
 };
 
 
@@ -178,8 +179,8 @@ static struct wpabuf * eap_pax_process_std_1(struct eap_pax_data *data,
 		    data->rand.r.y, EAP_PAX_RAND_LEN);
 
 	if (eap_pax_initial_key_derivation(req->mac_id, data->ak, data->rand.e,
-					   data->mk, data->ck, data->ick) < 0)
-	{
+					   data->mk, data->ck, data->ick,
+					   data->mid) < 0) {
 		ret->ignore = TRUE;
 		return NULL;
 	}
@@ -501,6 +502,26 @@ static u8 * eap_pax_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
 }
 
 
+static u8 * eap_pax_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
+{
+	struct eap_pax_data *data = priv;
+	u8 *sid;
+
+	if (data->state != PAX_DONE)
+		return NULL;
+
+	sid = os_malloc(1 + EAP_PAX_MID_LEN);
+	if (sid == NULL)
+		return NULL;
+
+	*len = 1 + EAP_PAX_MID_LEN;
+	sid[0] = EAP_TYPE_PAX;
+	os_memcpy(sid + 1, data->mid, EAP_PAX_MID_LEN);
+
+	return sid;
+}
+
+
 int eap_peer_pax_register(void)
 {
 	struct eap_method *eap;
@@ -517,6 +538,7 @@ int eap_peer_pax_register(void)
 	eap->isKeyAvailable = eap_pax_isKeyAvailable;
 	eap->getKey = eap_pax_getKey;
 	eap->get_emsk = eap_pax_get_emsk;
+	eap->getSessionId = eap_pax_get_session_id;
 
 	ret = eap_peer_method_register(eap);
 	if (ret)

src/eap_server/eap_server_pax.c

@@ -36,6 +36,7 @@ struct eap_pax_data {
 	u8 mk[EAP_PAX_MK_LEN];
 	u8 ck[EAP_PAX_CK_LEN];
 	u8 ick[EAP_PAX_ICK_LEN];
+	u8 mid[EAP_PAX_MID_LEN];
 	int keys_set;
 	char *cid;
 	size_t cid_len;
@@ -387,7 +388,7 @@ static void eap_pax_process_std_2(struct eap_sm *sm,
 
 	if (eap_pax_initial_key_derivation(data->mac_id, data->ak,
 					   data->rand.e, data->mk, data->ck,
-					   data->ick) < 0) {
+					   data->ick, data->mid) < 0) {
 		wpa_printf(MSG_INFO, "EAP-PAX: Failed to complete initial "
 			   "key derivation");
 		data->state = FAILURE;
@@ -541,6 +542,26 @@ static Boolean eap_pax_isSuccess(struct eap_sm *sm, void *priv)
 }
 
 
+static u8 * eap_pax_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
+{
+	struct eap_pax_data *data = priv;
+	u8 *sid;
+
+	if (data->state != SUCCESS)
+		return NULL;
+
+	sid = os_malloc(1 + EAP_PAX_MID_LEN);
+	if (sid == NULL)
+		return NULL;
+
+	*len = 1 + EAP_PAX_MID_LEN;
+	sid[0] = EAP_TYPE_PAX;
+	os_memcpy(sid + 1, data->mid, EAP_PAX_MID_LEN);
+
+	return sid;
+}
+
+
 int eap_server_pax_register(void)
 {
 	struct eap_method *eap;
@@ -560,6 +581,7 @@ int eap_server_pax_register(void)
 	eap->getKey = eap_pax_getKey;
 	eap->isSuccess = eap_pax_isSuccess;
 	eap->get_emsk = eap_pax_get_emsk;
+	eap->getSessionId = eap_pax_get_session_id;
 
 	ret = eap_server_method_register(eap);
 	if (ret)