wifi: mac80211: prevent 4-addr use on MLDs

We haven't tried this yet, and it's not very likely to
work well right now, so for now disable 4-addr use on
interfaces that are MLDs.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://lore.kernel.org/r/20220902161143.f2e4cc2efaa1.I5924e8fb44a2d098b676f5711b36bbc1b1bd68e2@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -226,6 +226,10 @@ static int ieee80211_change_iface(struct wiphy *wiphy,
 		if (params->use_4addr == ifmgd->use_4addr)
 			return 0;
 
+		/* FIXME: no support for 4-addr MLO yet */
+		if (sdata->vif.valid_links)
+			return -EOPNOTSUPP;
+
 		sdata->u.mgd.use_4addr = params->use_4addr;
 		if (!ifmgd->associated)
 			return 0;
@@ -4697,6 +4701,9 @@ static int ieee80211_add_intf_link(struct wiphy *wiphy,
 {
 	struct ieee80211_sub_if_data *sdata = IEEE80211_WDEV_TO_SUB_IF(wdev);
 
+	if (wdev->use_4addr)
+		return -EOPNOTSUPP;
+
 	return ieee80211_vif_set_links(sdata, wdev->valid_links);
 }
 

net/mac80211/mlme.c

@@ -6894,6 +6894,10 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 		}
 	}
 
+	/* FIXME: no support for 4-addr MLO yet */
+	if (sdata->u.mgd.use_4addr && req->link_id >= 0)
+		return -EOPNOTSUPP;
+
 	assoc_data = kzalloc(size, GFP_KERNEL);
 	if (!assoc_data)
 		return -ENOMEM;