nl80211: don't expose wdev->ssid for most interfaces

For mesh, this is simply wrong - there's no SSID, only the
mesh ID, so don't expose it at all.
For (P2P) client, it's wrong, because it exposes an internal
value that's only used when certain APIs are used.
For AP, it's actually the only correct case, so leave that.
All other interface types shouldn't be setting this anyway,
so there it won't change anything.

Fixes: b84e7a05 ("nl80211: send the NL80211_ATTR_SSID in nl80211_send_iface()")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -2605,10 +2605,32 @@ static int nl80211_send_iface(struct sk_buff *msg, u32 portid, u32 seq, int flag
 			goto nla_put_failure;
 	}
 
-	if (wdev->ssid_len) {
-		if (nla_put(msg, NL80211_ATTR_SSID, wdev->ssid_len, wdev->ssid))
+	wdev_lock(wdev);
+	switch (wdev->iftype) {
+	case NL80211_IFTYPE_AP:
+		if (wdev->ssid_len &&
+		    nla_put(msg, NL80211_ATTR_SSID, wdev->ssid_len, wdev->ssid))
 			goto nla_put_failure;
+		break;
+	case NL80211_IFTYPE_STATION:
+	case NL80211_IFTYPE_P2P_CLIENT:
+	case NL80211_IFTYPE_ADHOC: {
+		const u8 *ssid_ie;
+		if (!wdev->current_bss)
+			break;
+		ssid_ie = ieee80211_bss_get_ie(&wdev->current_bss->pub,
+					       WLAN_EID_SSID);
+		if (!ssid_ie)
+			break;
+		if (nla_put(msg, NL80211_ATTR_SSID, ssid_ie[1], ssid_ie + 2))
+			goto nla_put_failure;
+		break;
 		}
+	default:
+		/* nothing */
+		break;
+	}
+	wdev_unlock(wdev);
 
 	genlmsg_end(msg, hdr);
 	return 0;