wifi: mac80211: obtain AP HT/VHT data for assoc request

In the association request, we make some parameters depend on the
AP's HT/VHT information. This was broken by my code because it no
longer filled that information, making it all zero.

For HT that meant we wouldn't reduce our capabilities to 20 MHz if
needed, and for VHT we lost beamforming capabilities.

Fix this. It seems like it may even have been broken for all but
the assoc link before.

Fixes: 310c8387 ("wifi: mac80211: clean up connection process")
Reviewed-by: Miriam Rachel Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240228094207.7dc812c2060a.Ibd591f9c214b4e166cf7171db3cf63bda8e3c9fd@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mlme.c

@@ -8049,6 +8049,67 @@ ieee80211_setup_assoc_link(struct ieee80211_sub_if_data *sdata,
 	}
 }
 
+static int
+ieee80211_mgd_get_ap_ht_vht_capa(struct ieee80211_sub_if_data *sdata,
+				 struct ieee80211_mgd_assoc_data *assoc_data,
+				 int link_id)
+{
+	struct cfg80211_bss *cbss = assoc_data->link[link_id].bss;
+	enum nl80211_band band = cbss->channel->band;
+	struct ieee80211_supported_band *sband;
+	const struct element *elem;
+	int err;
+
+	/* neither HT nor VHT elements used on 6 GHz */
+	if (band == NL80211_BAND_6GHZ)
+		return 0;
+
+	if (assoc_data->link[link_id].conn.mode < IEEE80211_CONN_MODE_HT)
+		return 0;
+
+	rcu_read_lock();
+	elem = ieee80211_bss_get_elem(cbss, WLAN_EID_HT_OPERATION);
+	if (!elem || elem->datalen < sizeof(struct ieee80211_ht_operation)) {
+		mlme_link_id_dbg(sdata, link_id, "no HT operation on BSS %pM\n",
+				 cbss->bssid);
+		err = -EINVAL;
+		goto out_rcu;
+	}
+	assoc_data->link[link_id].ap_ht_param =
+		((struct ieee80211_ht_operation *)(elem->data))->ht_param;
+	rcu_read_unlock();
+
+	if (assoc_data->link[link_id].conn.mode < IEEE80211_CONN_MODE_VHT)
+		return 0;
+
+	/* some drivers want to support VHT on 2.4 GHz even */
+	sband = sdata->local->hw.wiphy->bands[band];
+	if (!sband->vht_cap.vht_supported)
+		return 0;
+
+	rcu_read_lock();
+	elem = ieee80211_bss_get_elem(cbss, WLAN_EID_VHT_CAPABILITY);
+	/* but even then accept it not being present on the AP */
+	if (!elem && band == NL80211_BAND_2GHZ) {
+		err = 0;
+		goto out_rcu;
+	}
+	if (!elem || elem->datalen < sizeof(struct ieee80211_vht_cap)) {
+		mlme_link_id_dbg(sdata, link_id, "no VHT capa on BSS %pM\n",
+				 cbss->bssid);
+		err = -EINVAL;
+		goto out_rcu;
+	}
+	memcpy(&assoc_data->link[link_id].ap_vht_cap, elem->data,
+	       sizeof(struct ieee80211_vht_cap));
+	rcu_read_unlock();
+
+	return 0;
+out_rcu:
+	rcu_read_unlock();
+	return err;
+}
+
 int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 			struct cfg80211_assoc_request *req)
 {
@@ -8193,6 +8254,14 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 				req->links[i].error = err;
 				goto err_free;
 			}
+
+			err = ieee80211_mgd_get_ap_ht_vht_capa(sdata,
+							       assoc_data, i);
+			if (err) {
+				err = -EINVAL;
+				req->links[i].error = err;
+				goto err_free;
+			}
 		}
 
 		assoc_data->wmm = true;
@@ -8228,6 +8297,10 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 						       &assoc_data->link[0].conn);
 
 		uapsd_supported = bss->uapsd_supported;
+
+		err = ieee80211_mgd_get_ap_ht_vht_capa(sdata, assoc_data, 0);
+		if (err)
+			goto err_free;
 	}
 
 	assoc_data->spp_amsdu = req->flags & ASSOC_REQ_SPP_AMSDU;