nl80211: AP MLD support for adding multi link stations

Multi link stations are represented in the kernel using a single
station with multiple links and the first ADD_STA command also
creates the first link. Subsequent links should be added with
LINK_ADD commands.

Implement this logic and provide the required MLD information per
station/link.

Signed-off-by: Andrei Otcheretianski <andrei.otcheretianski@intel.com>

src/ap/ap_drv_ops.c

@@ -459,6 +459,7 @@ int hostapd_sta_add(struct hostapd_data *hapd,
 	params.qosinfo = qosinfo;
 	params.support_p2p_ps = supp_p2p_ps;
 	params.set = set;
+	params.mld_link_id = -1;
 	return hapd->driver->sta_add(hapd->drv_priv, &params);
 }
 

src/drivers/driver.h

@@ -2403,6 +2403,10 @@ struct hostapd_sta_add_params {
 	const u8 *supp_oper_classes;
 	size_t supp_oper_classes_len;
 	int support_p2p_ps;
+
+	bool mld_link_sta;
+	s8 mld_link_id;
+	const u8 *mld_link_addr;
 };
 
 struct mac_address {

src/drivers/driver_nl80211.c

@@ -5285,16 +5285,29 @@ static int wpa_driver_nl80211_sta_add(void *priv,
 	struct nl_msg *msg;
 	struct nl80211_sta_flag_update upd;
 	int ret = -ENOBUFS;
+	u8 cmd;
+	const char *cmd_string;
 
 	if ((params->flags & WPA_STA_TDLS_PEER) &&
 	    !(drv->capa.flags & WPA_DRIVER_FLAGS_TDLS_SUPPORT))
 		return -EOPNOTSUPP;
 
+	if (params->mld_link_sta) {
+		cmd = params->set ? NL80211_CMD_MODIFY_LINK_STA :
+			NL80211_CMD_ADD_LINK_STA;
+		cmd_string = params->set ? "NL80211_CMD_MODIFY_LINK_STA" :
+			"NL80211_CMD_ADD_LINK_STA";
+	} else {
+		cmd = params->set ? NL80211_CMD_SET_STATION :
+			NL80211_CMD_NEW_STATION;
+		cmd_string = params->set ? "NL80211_CMD_SET_STATION" :
+			"NL80211_CMD_NEW_STATION";
+	}
+
 	wpa_printf(MSG_DEBUG, "nl80211: %s STA " MACSTR,
-		   params->set ? "Set" : "Add", MAC2STR(params->addr));
+		   cmd_string, MAC2STR(params->addr));
-	msg = nl80211_bss_msg(bss, 0, params->set ? NL80211_CMD_SET_STATION :
+	msg = nl80211_bss_msg(bss, 0, cmd);
-			      NL80211_CMD_NEW_STATION);
+	if (!msg)
-	if (!msg || nla_put(msg, NL80211_ATTR_MAC, ETH_ALEN, params->addr))
 		goto fail;
 
 	/*
@@ -5512,12 +5525,43 @@ static int wpa_driver_nl80211_sta_add(void *priv,
 		nla_nest_end(msg, wme);
 	}
 
+	/* In case we are an AP MLD need to always specify the link ID */
+	if (params->mld_link_id >= 0) {
+		wpa_printf(MSG_DEBUG, "  * mld_link_id=%d",
+			   params->mld_link_id);
+		if (nla_put_u8(msg, NL80211_ATTR_MLO_LINK_ID,
+			       params->mld_link_id))
+			goto fail;
+
+		/*
+		 * If the link address is specified the station is a non-AP MLD
+		 * and thus need to provide the MLD address as the station
+		 * address, and the non-AP MLD link address as the link address.
+		 */
+		if (params->mld_link_addr) {
+			wpa_printf(MSG_DEBUG, "  * mld_link_addr=" MACSTR,
+				   MAC2STR(params->mld_link_addr));
+
+			if (nla_put(msg, NL80211_ATTR_MLD_ADDR,
+				    ETH_ALEN, params->addr) ||
+			    nla_put(msg, NL80211_ATTR_MAC, ETH_ALEN,
+				    params->mld_link_addr))
+				goto fail;
+		} else {
+			if (nla_put(msg, NL80211_ATTR_MAC, ETH_ALEN,
+				    params->addr))
+				goto fail;
+		}
+	} else {
+		if (nla_put(msg, NL80211_ATTR_MAC, ETH_ALEN, params->addr))
+			goto fail;
+	}
+
 	ret = send_and_recv_msgs(drv, msg, NULL, NULL, NULL, NULL);
 	msg = NULL;
 	if (ret)
-		wpa_printf(MSG_DEBUG, "nl80211: NL80211_CMD_%s_STATION "
+		wpa_printf(MSG_DEBUG, "nl80211: %s result: %d (%s)",
-			   "result: %d (%s)", params->set ? "SET" : "NEW", ret,
+			   cmd_string, ret, strerror(-ret));
-			   strerror(-ret));
 	if (ret == -EEXIST)
 		ret = 0;
 fail:

wpa_supplicant/driver_i.h

@@ -350,8 +350,11 @@ static inline int wpa_drv_set_ap(struct wpa_supplicant *wpa_s,
 static inline int wpa_drv_sta_add(struct wpa_supplicant *wpa_s,
 				  struct hostapd_sta_add_params *params)
 {
-	if (wpa_s->driver->sta_add)
+	if (wpa_s->driver->sta_add) {
+		/* Set link_id to -1 as it's needed for AP only */
+		params->mld_link_id = -1;
 		return wpa_s->driver->sta_add(wpa_s->drv_priv, params);
+	}
 	return -1;
 }