wpa_supplicant: Support Multi-AP backhaul STA onboarding with WPS

The Wi-Fi Alliance Multi-AP Specification v1.0 allows onboarding of a
backhaul STA through WPS. To enable this, the backhaul STA needs to add
a Multi-AP IE to the WFA vendor extension element in the WSC M1 message
that indicates it supports the Multi-AP backhaul STA role. The Registrar
(if it support Multi-AP onboarding) will respond to that with a WSC M8
message that also contains the Multi-AP IE, and that contains the
credentials for the backhaul SSID (which may be different from the SSID
on which WPS is performed).

Introduce a new parameter to wpas_wps_start_pbc() and allow it to be
set via control interface's new multi_ap=1 parameter of WPS_PBC call.
multi_ap_backhaul_sta is set to 1 in the automatically created SSID.
Thus, if the AP does not support Multi-AP, association will fail and
WPS will be terminated.

Only wps_pbc is supported.

This commit adds the multi_ap argument only to the control socket
interface, not to the D-Bus interface.

Since WPS associates with the fronthaul BSS instead of the backhaul BSS,
we should not drop association if the AP announces fronthaul-only BSS.
Still, we should only do that in the specific case of WPS. Therefore,
add a check to multi_ap_process_assoc_resp() to allow association with a
fronthaul-only BSS if and only if key_mgmt contains WPS.

Signed-off-by: Davina Lu <ylu@quantenna.com>
Signed-off-by: Igor Mitsyanko <igor.mitsyanko.os@quantenna.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Cc: Marianna Carrera <marianna.carrera.so@quantenna.com>

src/eap_peer/eap_wsc.c

@@ -255,6 +255,9 @@ static void * eap_wsc_init(struct eap_sm *sm)
 		cfg.new_ap_settings = &new_ap_settings;
 	}
 
+	if (os_strstr(phase1, "multi_ap=1"))
+		cfg.multi_ap_backhaul_sta = 1;
+
 	data->wps = wps_init(&cfg);
 	if (data->wps == NULL) {
 		os_free(data);

src/wps/wps.c

@@ -145,6 +145,8 @@ struct wps_data * wps_init(const struct wps_config *cfg)
 		data->peer_pubkey_hash_set = 1;
 	}
 
+	data->multi_ap_backhaul_sta = cfg->multi_ap_backhaul_sta;
+
 	return data;
 }
 

src/wps/wps.h

@@ -187,6 +187,12 @@ struct wps_config {
 	 * peer_pubkey_hash - Peer public key hash or %NULL if not known
 	 */
 	const u8 *peer_pubkey_hash;
+
+	/**
+	 * multi_ap_backhaul_sta - Whether this is a Multi-AP backhaul STA
+	 * enrollee
+	 */
+	int multi_ap_backhaul_sta;
 };
 
 struct wps_data * wps_init(const struct wps_config *cfg);

src/wps/wps_enrollee.c

@@ -105,6 +105,7 @@ static struct wpabuf * wps_build_m1(struct wps_data *wps)
 {
 	struct wpabuf *msg;
 	u16 config_methods;
+	u8 multi_ap_backhaul_sta = 0;
 
 	if (random_get_bytes(wps->nonce_e, WPS_NONCE_LEN) < 0)
 		return NULL;
@@ -134,6 +135,9 @@ static struct wpabuf * wps_build_m1(struct wps_data *wps)
 				    WPS_CONFIG_PHY_PUSHBUTTON);
 	}
 
+	if (wps->multi_ap_backhaul_sta)
+		multi_ap_backhaul_sta = MULTI_AP_BACKHAUL_STA;
+
 	if (wps_build_version(msg) ||
 	    wps_build_msg_type(msg, WPS_M1) ||
 	    wps_build_uuid_e(msg, wps->uuid_e) ||
@@ -152,7 +156,7 @@ static struct wpabuf * wps_build_m1(struct wps_data *wps)
 	    wps_build_dev_password_id(msg, wps->dev_pw_id) ||
 	    wps_build_config_error(msg, WPS_CFG_NO_ERROR) ||
 	    wps_build_os_version(&wps->wps->dev, msg) ||
-	    wps_build_wfa_ext(msg, 0, NULL, 0, 0) ||
+	    wps_build_wfa_ext(msg, 0, NULL, 0, multi_ap_backhaul_sta) ||
 	    wps_build_vendor_ext_m1(&wps->wps->dev, msg)) {
 		wpabuf_free(msg);
 		return NULL;

src/wps/wps_i.h

@@ -125,6 +125,8 @@ struct wps_data {
 	int pbc_in_m1;
 
 	struct wps_nfc_pw_token *nfc_pw_token;
+
+	int multi_ap_backhaul_sta;
 };