EAP-pwd peer: Export Session-Id through getSessionId callback

EAP-pwd was already deriving the EAP Session-Id, but it was not yet
exposed through the EAP method API.

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

src/eap_common/eap_pwd_common.c

@@ -284,11 +284,10 @@ int compute_password_element(EAP_PWD_group *grp, u16 num,
 int compute_keys(EAP_PWD_group *grp, BN_CTX *bnctx, BIGNUM *k,
 		 BIGNUM *peer_scalar, BIGNUM *server_scalar,
 		 u8 *confirm_peer, u8 *confirm_server,
-		 u32 *ciphersuite, u8 *msk, u8 *emsk)
+		 u32 *ciphersuite, u8 *msk, u8 *emsk, u8 *session_id)
 {
 	struct crypto_hash *hash;
 	u8 mk[SHA256_MAC_LEN], *cruft;
-	u8 session_id[SHA256_MAC_LEN + 1];
 	u8 msk_emsk[EAP_MSK_LEN + EAP_EMSK_LEN];
 	int offset;
 

src/eap_common/eap_pwd_common.h

@@ -59,7 +59,7 @@ struct eap_pwd_id {
 int compute_password_element(EAP_PWD_group *, u16, u8 *, int, u8 *, int, u8 *,
 			     int, u8 *);
 int compute_keys(EAP_PWD_group *, BN_CTX *, BIGNUM *, BIGNUM *, BIGNUM *,
-		 u8 *, u8 *, u32 *, u8 *, u8 *);
+		 u8 *, u8 *, u32 *, u8 *, u8 *, u8 *);
 struct crypto_hash * eap_pwd_h_init(void);
 void eap_pwd_h_update(struct crypto_hash *hash, const u8 *data, size_t len);
 void eap_pwd_h_final(struct crypto_hash *hash, u8 *digest);

src/eap_peer/eap_pwd.c

@@ -43,6 +43,7 @@ struct eap_pwd_data {
 
 	u8 msk[EAP_MSK_LEN];
 	u8 emsk[EAP_EMSK_LEN];
+	u8 session_id[1 + SHA256_MAC_LEN];
 
 	BN_CTX *bnctx;
 };
@@ -189,6 +190,25 @@ static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
 }
 
 
+static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
+{
+	struct eap_pwd_data *data = priv;
+	u8 *id;
+
+	if (data->state != SUCCESS)
+		return NULL;
+
+	id = os_malloc(1 + SHA256_MAC_LEN);
+	if (id == NULL)
+		return NULL;
+
+	os_memcpy(id, data->session_id, 1 + SHA256_MAC_LEN);
+	*len = 1 + SHA256_MAC_LEN;
+
+	return id;
+}
+
+
 static void
 eap_pwd_perform_id_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
 			    struct eap_method_ret *ret,
@@ -647,7 +667,7 @@ eap_pwd_perform_confirm_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
 
 	if (compute_keys(data->grp, data->bnctx, data->k,
 			 data->my_scalar, data->server_scalar, conf, ptr,
-			 &cs, data->msk, data->emsk) < 0) {
+			 &cs, data->msk, data->emsk, data->session_id) < 0) {
 		wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute MSK | "
 			   "EMSK");
 		goto fin;
@@ -934,6 +954,7 @@ int eap_peer_pwd_register(void)
 	eap->process = eap_pwd_process;
 	eap->isKeyAvailable = eap_pwd_key_available;
 	eap->getKey = eap_pwd_getkey;
+	eap->getSessionId = eap_pwd_get_session_id;
 	eap->get_emsk = eap_pwd_get_emsk;
 
 	ret = eap_peer_method_register(eap);

src/eap_server/eap_server_pwd.c

@@ -45,6 +45,7 @@ struct eap_pwd_data {
 
 	u8 msk[EAP_MSK_LEN];
 	u8 emsk[EAP_EMSK_LEN];
+	u8 session_id[1 + SHA256_MAC_LEN];
 
 	BN_CTX *bnctx;
 };
@@ -841,7 +842,8 @@ eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
 	wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified");
 	if (compute_keys(data->grp, data->bnctx, data->k,
 			 data->peer_scalar, data->my_scalar, conf,
-			 data->my_confirm, &cs, data->msk, data->emsk) < 0)
+			 data->my_confirm, &cs, data->msk, data->emsk,
+			 data->session_id) < 0)
 		eap_pwd_state(data, FAILURE);
 	else
 		eap_pwd_state(data, SUCCESS);