DPP: Expose enrollee pubkey hash for identification

Just like with WPA-PSK and keyids it may be desired to identify
connecting clients to provide additional network filtering.

This does:

 - extend DPP_EVENT_AUTH_SUCCESS to expose public
   key hash of the peer so the system can pick it
   up and use for identification later

 - store public key hash in PMKSA from DPP Network
   Intro for later use

 - extend sta mib to print out the dpp_pkhash
   from PMKSA if present

 - extend AP_STA_CONNECTED to include the
   dpp_pkhash from PMKSA if present

Signed-off-by: Michal Kazior <michal@plume.com>

src/ap/ctrl_iface_ap.c

@@ -218,6 +218,7 @@ static int hostapd_ctrl_iface_sta_mib(struct hostapd_data *hapd,
 {
 	int len, res, ret, i;
 	const char *keyid;
+	const u8 *dpp_pkhash;
 
 	if (!sta)
 		return 0;
@@ -386,6 +387,18 @@ static int hostapd_ctrl_iface_sta_mib(struct hostapd_data *hapd,
 			len += ret;
 	}
 
+	dpp_pkhash = ap_sta_wpa_get_dpp_pkhash(hapd, sta);
+	if (dpp_pkhash) {
+		ret = os_snprintf(buf + len, buflen - len, "dpp_pkhash=");
+		if (!os_snprintf_error(buflen - len, ret))
+			len += ret;
+		len += wpa_snprintf_hex(buf + len, buflen - len, dpp_pkhash,
+					SHA256_MAC_LEN);
+		ret = os_snprintf(buf + len, buflen - len, "\n");
+		if (!os_snprintf_error(buflen - len, ret))
+			len += ret;
+	}
+
 	return len;
 }
 

src/ap/dpp_hostapd.c

@@ -2051,6 +2051,7 @@ static void hostapd_dpp_rx_peer_disc_req(struct hostapd_data *hapd,
 	os_time_t expire;
 	int expiration;
 	enum dpp_status_error res;
+	u8 pkhash[SHA256_MAC_LEN];
 
 	os_memset(&intro, 0, sizeof(intro));
 
@@ -2087,7 +2088,7 @@ static void hostapd_dpp_rx_peer_disc_req(struct hostapd_data *hapd,
 			     wpabuf_len(hapd->conf->dpp_netaccesskey),
 			     wpabuf_head(hapd->conf->dpp_csign),
 			     wpabuf_len(hapd->conf->dpp_csign),
-			     connector, connector_len, &expire);
+			     connector, connector_len, &expire, pkhash);
 	if (res == 255) {
 		wpa_printf(MSG_INFO,
 			   "DPP: Network Introduction protocol resulted in internal failure (peer "
@@ -2132,9 +2133,9 @@ static void hostapd_dpp_rx_peer_disc_req(struct hostapd_data *hapd,
 	else
 		expiration = 0;
 
-	if (wpa_auth_pmksa_add2(hapd->wpa_auth, src, intro.pmk, intro.pmk_len,
+	if (wpa_auth_pmksa_add3(hapd->wpa_auth, src, intro.pmk, intro.pmk_len,
 				intro.pmkid, expiration,
-				WPA_KEY_MGMT_DPP) < 0) {
+				WPA_KEY_MGMT_DPP, pkhash) < 0) {
 		wpa_printf(MSG_ERROR, "DPP: Failed to add PMKSA cache entry");
 		goto done;
 	}
@@ -2792,6 +2793,7 @@ hostapd_dpp_rx_priv_peer_intro_update(struct hostapd_data *hapd, const u8 *src,
 	os_time_t expire;
 	int expiration;
 	enum dpp_status_error res;
+	u8 pkhash[SHA256_MAC_LEN];
 
 	os_memset(&intro, 0, sizeof(intro));
 
@@ -2869,7 +2871,7 @@ hostapd_dpp_rx_priv_peer_intro_update(struct hostapd_data *hapd, const u8 *src,
 			     wpabuf_len(hapd->conf->dpp_netaccesskey),
 			     wpabuf_head(hapd->conf->dpp_csign),
 			     wpabuf_len(hapd->conf->dpp_csign),
-			     connector, connector_len, &expire);
+			     connector, connector_len, &expire, pkhash);
 	if (res == 255) {
 		wpa_printf(MSG_INFO,
 			   "DPP: Network Introduction protocol resulted in internal failure (peer "
@@ -2903,9 +2905,9 @@ hostapd_dpp_rx_priv_peer_intro_update(struct hostapd_data *hapd, const u8 *src,
 	else
 		expiration = 0;
 
-	if (wpa_auth_pmksa_add2(hapd->wpa_auth, src, intro.pmk, intro.pmk_len,
+	if (wpa_auth_pmksa_add3(hapd->wpa_auth, src, intro.pmk, intro.pmk_len,
 				intro.pmkid, expiration,
-				WPA_KEY_MGMT_DPP) < 0) {
+				WPA_KEY_MGMT_DPP, pkhash) < 0) {
 		wpa_printf(MSG_ERROR, "DPP: Failed to add PMKSA cache entry");
 		goto done;
 	}

src/ap/pmksa_cache_auth.c

@@ -40,6 +40,7 @@ static void _pmksa_cache_free_entry(struct rsn_pmksa_cache_entry *entry)
 {
 	os_free(entry->vlan_desc);
 	os_free(entry->identity);
+	os_free(entry->dpp_pkhash);
 	wpabuf_free(entry->cui);
 #ifndef CONFIG_NO_RADIUS
 	radius_free_class(&entry->radius_class);

src/ap/pmksa_cache_auth.h

@@ -23,6 +23,8 @@ struct rsn_pmksa_cache_entry {
 	int akmp; /* WPA_KEY_MGMT_* */
 	u8 spa[ETH_ALEN];
 
+	u8 *dpp_pkhash; /* SHA256_MAC_LEN octet hash value of DPP Connector
+			 * public key */
 	u8 *identity;
 	size_t identity_len;
 	struct wpabuf *cui;

src/ap/sta_info.c

@@ -1260,6 +1260,13 @@ const char * ap_sta_wpa_get_keyid(struct hostapd_data *hapd,
 }
 
 
+const u8 * ap_sta_wpa_get_dpp_pkhash(struct hostapd_data *hapd,
+				     struct sta_info *sta)
+{
+	return wpa_auth_get_dpp_pkhash(sta->wpa_sm);
+}
+
+
 void ap_sta_set_authorized(struct hostapd_data *hapd, struct sta_info *sta,
 			   int authorized)
 {
@@ -1298,10 +1305,13 @@ void ap_sta_set_authorized(struct hostapd_data *hapd, struct sta_info *sta,
 					sta->addr, authorized, dev_addr);
 
 	if (authorized) {
+		const u8 *dpp_pkhash;
 		const char *keyid;
+		char dpp_pkhash_buf[100];
 		char keyid_buf[100];
 		char ip_addr[100];
 
+		dpp_pkhash_buf[0] = '\0';
 		keyid_buf[0] = '\0';
 		ip_addr[0] = '\0';
 #ifdef CONFIG_P2P
@@ -1319,14 +1329,27 @@ void ap_sta_set_authorized(struct hostapd_data *hapd, struct sta_info *sta,
 				    " keyid=%s", keyid);
 		}
 
-		wpa_msg(hapd->msg_ctx, MSG_INFO, AP_STA_CONNECTED "%s%s%s",
+		dpp_pkhash = ap_sta_wpa_get_dpp_pkhash(hapd, sta);
-			buf, ip_addr, keyid_buf);
+		if (dpp_pkhash) {
+			const char *prefix = " dpp_pkhash=";
+			size_t plen = os_strlen(prefix);
+
+			os_strlcpy(dpp_pkhash_buf, prefix,
+				   sizeof(dpp_pkhash_buf));
+			wpa_snprintf_hex(&dpp_pkhash_buf[plen],
+					 sizeof(dpp_pkhash_buf) - plen,
+					 dpp_pkhash, SHA256_MAC_LEN);
+		}
+
+		wpa_msg(hapd->msg_ctx, MSG_INFO, AP_STA_CONNECTED "%s%s%s%s",
+			buf, ip_addr, keyid_buf, dpp_pkhash_buf);
 
 		if (hapd->msg_ctx_parent &&
 		    hapd->msg_ctx_parent != hapd->msg_ctx)
 			wpa_msg_no_global(hapd->msg_ctx_parent, MSG_INFO,
-					  AP_STA_CONNECTED "%s%s%s",
+					  AP_STA_CONNECTED "%s%s%s%s",
-					  buf, ip_addr, keyid_buf);
+					  buf, ip_addr, keyid_buf,
+					  dpp_pkhash_buf);
 	} else {
 		wpa_msg(hapd->msg_ctx, MSG_INFO, AP_STA_DISCONNECTED "%s", buf);
 

src/ap/sta_info.h

@@ -354,6 +354,8 @@ void ap_sta_stop_sa_query(struct hostapd_data *hapd, struct sta_info *sta);
 int ap_check_sa_query_timeout(struct hostapd_data *hapd, struct sta_info *sta);
 const char * ap_sta_wpa_get_keyid(struct hostapd_data *hapd,
 				  struct sta_info *sta);
+const u8 * ap_sta_wpa_get_dpp_pkhash(struct hostapd_data *hapd,
+				     struct sta_info *sta);
 void ap_sta_disconnect(struct hostapd_data *hapd, struct sta_info *sta,
 		       const u8 *addr, u16 reason);
 

src/ap/wpa_auth.c

@@ -4856,6 +4856,14 @@ const u8 * wpa_auth_get_pmk(struct wpa_state_machine *sm, int *len)
 }
 
 
+const u8 * wpa_auth_get_dpp_pkhash(struct wpa_state_machine *sm)
+{
+	if (!sm || !sm->pmksa)
+		return NULL;
+	return sm->pmksa->dpp_pkhash;
+}
+
+
 int wpa_auth_sta_key_mgmt(struct wpa_state_machine *sm)
 {
 	if (!sm)
@@ -5018,6 +5026,29 @@ int wpa_auth_pmksa_add2(struct wpa_authenticator *wpa_auth, const u8 *addr,
 }
 
 
+int wpa_auth_pmksa_add3(struct wpa_authenticator *wpa_auth, const u8 *addr,
+			const u8 *pmk, size_t pmk_len, const u8 *pmkid,
+			int session_timeout, int akmp, const u8 *dpp_pkhash)
+{
+	struct rsn_pmksa_cache_entry *entry;
+
+	if (wpa_auth->conf.disable_pmksa_caching)
+		return -1;
+
+	wpa_hexdump_key(MSG_DEBUG, "RSN: Cache PMK (3)", pmk, PMK_LEN);
+	entry = pmksa_cache_auth_add(wpa_auth->pmksa, pmk, pmk_len, pmkid,
+				 NULL, 0, wpa_auth->addr, addr, session_timeout,
+				 NULL, akmp);
+	if (!entry)
+		return -1;
+
+	if (dpp_pkhash)
+		entry->dpp_pkhash = os_memdup(dpp_pkhash, SHA256_MAC_LEN);
+
+	return 0;
+}
+
+
 void wpa_auth_pmksa_remove(struct wpa_authenticator *wpa_auth,
 			   const u8 *sta_addr)
 {

src/ap/wpa_auth.h

@@ -410,6 +410,7 @@ void wpa_auth_countermeasures_start(struct wpa_authenticator *wpa_auth);
 int wpa_auth_pairwise_set(struct wpa_state_machine *sm);
 int wpa_auth_get_pairwise(struct wpa_state_machine *sm);
 const u8 * wpa_auth_get_pmk(struct wpa_state_machine *sm, int *len);
+const u8 * wpa_auth_get_dpp_pkhash(struct wpa_state_machine *sm);
 int wpa_auth_sta_key_mgmt(struct wpa_state_machine *sm);
 int wpa_auth_sta_wpa_version(struct wpa_state_machine *sm);
 int wpa_auth_sta_ft_tk_already_set(struct wpa_state_machine *sm);
@@ -435,6 +436,9 @@ void wpa_auth_add_sae_pmkid(struct wpa_state_machine *sm, const u8 *pmkid);
 int wpa_auth_pmksa_add2(struct wpa_authenticator *wpa_auth, const u8 *addr,
 			const u8 *pmk, size_t pmk_len, const u8 *pmkid,
 			int session_timeout, int akmp);
+int wpa_auth_pmksa_add3(struct wpa_authenticator *wpa_auth, const u8 *addr,
+			const u8 *pmk, size_t pmk_len, const u8 *pmkid,
+			int session_timeout, int akmp, const u8 *dpp_pkhash);
 void wpa_auth_pmksa_remove(struct wpa_authenticator *wpa_auth,
 			   const u8 *sta_addr);
 int wpa_auth_pmksa_list(struct wpa_authenticator *wpa_auth, char *buf,

src/common/dpp.c

@@ -4141,7 +4141,7 @@ dpp_peer_intro(struct dpp_introduction *intro, const char *own_connector,
 	       const u8 *net_access_key, size_t net_access_key_len,
 	       const u8 *csign_key, size_t csign_key_len,
 	       const u8 *peer_connector, size_t peer_connector_len,
-	       os_time_t *expiry)
+	       os_time_t *expiry, u8 *peer_key_hash)
 {
 	struct json_token *root = NULL, *netkey, *token;
 	struct json_token *own_root = NULL;
@@ -4264,6 +4264,9 @@ dpp_peer_intro(struct dpp_introduction *intro, const char *own_connector,
 	}
 #endif /* CONFIG_DPP3 */
 
+	if (peer_key_hash)
+		dpp_get_pubkey_hash(intro->peer_key, peer_key_hash);
+
 	ret = DPP_STATUS_OK;
 fail:
 	if (ret != DPP_STATUS_OK)
@@ -5036,8 +5039,18 @@ void dpp_global_deinit(struct dpp_global *dpp)
 
 void dpp_notify_auth_success(struct dpp_authentication *auth, int initiator)
 {
-	wpa_msg(auth->msg_ctx, MSG_INFO, DPP_EVENT_AUTH_SUCCESS "init=%d",
+	u8 hash[SHA256_MAC_LEN];
-		initiator);
+	char hex[SHA256_MAC_LEN * 2 + 1];
+
+	if (auth->peer_protocol_key) {
+		dpp_get_pubkey_hash(auth->peer_protocol_key, hash);
+		wpa_snprintf_hex(hex, sizeof(hex), hash, sizeof(hash));
+	} else {
+		hex[0] = '\0';
+	}
+	wpa_msg(auth->msg_ctx, MSG_INFO,
+		DPP_EVENT_AUTH_SUCCESS "init=%d pkhash=%s",
+		initiator, hex);
 }
 
 

src/common/dpp.h

@@ -669,7 +669,7 @@ dpp_peer_intro(struct dpp_introduction *intro, const char *own_connector,
 	       const u8 *net_access_key, size_t net_access_key_len,
 	       const u8 *csign_key, size_t csign_key_len,
 	       const u8 *peer_connector, size_t peer_connector_len,
-	       os_time_t *expiry);
+	       os_time_t *expiry, u8 *peer_key_hash);
 void dpp_peer_intro_deinit(struct dpp_introduction *intro);
 int dpp_get_connector_version(const char *connector);
 struct dpp_pkex * dpp_pkex_init(void *msg_ctx, struct dpp_bootstrap_info *bi,
@@ -853,6 +853,7 @@ struct dpp_reconfig_id * dpp_gen_reconfig_id(const u8 *csign_key,
 					     size_t pp_key_len);
 int dpp_update_reconfig_id(struct dpp_reconfig_id *id);
 void dpp_free_reconfig_id(struct dpp_reconfig_id *id);
+int dpp_get_pubkey_hash(struct crypto_ec_key *key, u8 *hash);
 
 #endif /* CONFIG_DPP */
 #endif /* DPP_H */

src/common/dpp_crypto.c

@@ -246,6 +246,27 @@ struct crypto_ec_key * dpp_set_pubkey_point(struct crypto_ec_key *group_key,
 }
 
 
+int dpp_get_pubkey_hash(struct crypto_ec_key *key, u8 *hash)
+{
+	struct wpabuf *uncomp;
+	const u8 *addr[1];
+	size_t len[1];
+	int res;
+
+	if (!key)
+		return -1;
+
+	uncomp = crypto_ec_key_get_pubkey_point(key, 1);
+	if (!uncomp)
+		return -1;
+	addr[0] = wpabuf_head(uncomp);
+	len[0] = wpabuf_len(uncomp);
+	res = sha256_vector(1, addr, len, hash);
+	wpabuf_free(uncomp);
+	return res;
+}
+
+
 struct crypto_ec_key * dpp_gen_keypair(const struct dpp_curve_params *curve)
 {
 	struct crypto_ec_key *key;

wpa_supplicant/dpp_supplicant.c

@@ -2677,7 +2677,7 @@ static void wpas_dpp_rx_peer_disc_resp(struct wpa_supplicant *wpa_s,
 			     ssid->dpp_netaccesskey_len,
 			     ssid->dpp_csign,
 			     ssid->dpp_csign_len,
-			     connector, connector_len, &expiry);
+			     connector, connector_len, &expiry, NULL);
 	if (res != DPP_STATUS_OK) {
 		wpa_printf(MSG_INFO,
 			   "DPP: Network Introduction protocol resulted in failure");
@@ -3830,7 +3830,7 @@ wpas_dpp_rx_priv_peer_intro_notify(struct wpa_supplicant *wpa_s,
 			     ssid->dpp_netaccesskey_len,
 			     ssid->dpp_csign,
 			     ssid->dpp_csign_len,
-			     connector, connector_len, &expiry);
+			     connector, connector_len, &expiry, NULL);
 	if (res != DPP_STATUS_OK) {
 		wpa_printf(MSG_INFO,
 			   "DPP: Network Introduction protocol resulted in failure");