mac80211: work around broken APs not including HT info

There are some APs, notably 2G/3G/4G Wifi routers, specifically the
"Onda PN51T", "Vodafone PocketWiFi 2", "ZTE MF60" and a similar
T-Mobile branded device [1] that erroneously don't include all the
needed information in (re)association response frames. Work around
this by assuming the information is the same as it was in the
beacon or probe response and using the data from there instead.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=58881.

[1] https://bbs.archlinux.org/viewtopic.php?pid=1277305

Note that this requires marking the first ieee802_11_parse_elems()
argument const, otherwise we'd get a compiler warning.

Cc: stable@vger.kernel.org
Reported-and-tested-by: Michal Zajac <manwe@manwe.pl>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ieee80211_i.h

@@ -1497,10 +1497,11 @@ static inline void ieee80211_tx_skb(struct ieee80211_sub_if_data *sdata,
 	ieee80211_tx_skb_tid(sdata, skb, 7);
 }
 
-u32 ieee802_11_parse_elems_crc(u8 *start, size_t len, bool action,
+u32 ieee802_11_parse_elems_crc(const u8 *start, size_t len, bool action,
 			       struct ieee802_11_elems *elems,
 			       u64 filter, u32 crc);
-static inline void ieee802_11_parse_elems(u8 *start, size_t len, bool action,
+static inline void ieee802_11_parse_elems(const u8 *start, size_t len,
+					  bool action,
 					  struct ieee802_11_elems *elems)
 {
 	ieee802_11_parse_elems_crc(start, len, action, elems, 0, 0);

net/mac80211/mlme.c

@@ -2522,8 +2522,11 @@ static bool ieee80211_assoc_success(struct ieee80211_sub_if_data *sdata,
 	u16 capab_info, aid;
 	struct ieee802_11_elems elems;
 	struct ieee80211_bss_conf *bss_conf = &sdata->vif.bss_conf;
+	const struct cfg80211_bss_ies *bss_ies = NULL;
+	struct ieee80211_mgd_assoc_data *assoc_data = ifmgd->assoc_data;
 	u32 changed = 0;
 	int err;
+	bool ret;
 
 	/* AssocResp and ReassocResp have identical structure */
 
@@ -2554,22 +2557,87 @@ static bool ieee80211_assoc_success(struct ieee80211_sub_if_data *sdata,
 
 	ifmgd->aid = aid;
 
+	/*
+	 * Some APs are erroneously not including some information in their
+	 * (re)association response frames. Try to recover by using the data
+	 * from the beacon or probe response. This seems to afflict mobile
+	 * 2G/3G/4G wifi routers, reported models include the "Onda PN51T",
+	 * "Vodafone PocketWiFi 2", "ZTE MF60" and a similar T-Mobile device.
+	 */
+	if ((assoc_data->wmm && !elems.wmm_param) ||
+	    (!(ifmgd->flags & IEEE80211_STA_DISABLE_HT) &&
+	     (!elems.ht_cap_elem || !elems.ht_operation)) ||
+	    (!(ifmgd->flags & IEEE80211_STA_DISABLE_VHT) &&
+	     (!elems.vht_cap_elem || !elems.vht_operation))) {
+		const struct cfg80211_bss_ies *ies;
+		struct ieee802_11_elems bss_elems;
+
+		rcu_read_lock();
+		ies = rcu_dereference(cbss->ies);
+		if (ies)
+			bss_ies = kmemdup(ies, sizeof(*ies) + ies->len,
+					  GFP_ATOMIC);
+		rcu_read_unlock();
+		if (!bss_ies)
+			return false;
+
+		ieee802_11_parse_elems(bss_ies->data, bss_ies->len,
+				       false, &bss_elems);
+		if (assoc_data->wmm &&
+		    !elems.wmm_param && bss_elems.wmm_param) {
+			elems.wmm_param = bss_elems.wmm_param;
+			sdata_info(sdata,
+				   "AP bug: WMM param missing from AssocResp\n");
+		}
+
+		/*
+		 * Also check if we requested HT/VHT, otherwise the AP doesn't
+		 * have to include the IEs in the (re)association response.
+		 */
+		if (!elems.ht_cap_elem && bss_elems.ht_cap_elem &&
+		    !(ifmgd->flags & IEEE80211_STA_DISABLE_HT)) {
+			elems.ht_cap_elem = bss_elems.ht_cap_elem;
+			sdata_info(sdata,
+				   "AP bug: HT capability missing from AssocResp\n");
+		}
+		if (!elems.ht_operation && bss_elems.ht_operation &&
+		    !(ifmgd->flags & IEEE80211_STA_DISABLE_HT)) {
+			elems.ht_operation = bss_elems.ht_operation;
+			sdata_info(sdata,
+				   "AP bug: HT operation missing from AssocResp\n");
+		}
+		if (!elems.vht_cap_elem && bss_elems.vht_cap_elem &&
+		    !(ifmgd->flags & IEEE80211_STA_DISABLE_VHT)) {
+			elems.vht_cap_elem = bss_elems.vht_cap_elem;
+			sdata_info(sdata,
+				   "AP bug: VHT capa missing from AssocResp\n");
+		}
+		if (!elems.vht_operation && bss_elems.vht_operation &&
+		    !(ifmgd->flags & IEEE80211_STA_DISABLE_VHT)) {
+			elems.vht_operation = bss_elems.vht_operation;
+			sdata_info(sdata,
+				   "AP bug: VHT operation missing from AssocResp\n");
+		}
+	}
+
 	/*
 	 * We previously checked these in the beacon/probe response, so
 	 * they should be present here. This is just a safety net.
 	 */
 	if (!(ifmgd->flags & IEEE80211_STA_DISABLE_HT) &&
 	    (!elems.wmm_param || !elems.ht_cap_elem || !elems.ht_operation)) {
 		sdata_info(sdata,
-			   "HT AP is missing WMM params or HT capability/operation in AssocResp\n");
-		return false;
+			   "HT AP is missing WMM params or HT capability/operation\n");
+		ret = false;
+		goto out;
 	}
 
 	if (!(ifmgd->flags & IEEE80211_STA_DISABLE_VHT) &&
 	    (!elems.vht_cap_elem || !elems.vht_operation)) {
 		sdata_info(sdata,
-			   "VHT AP is missing VHT capability/operation in AssocResp\n");
-		return false;
+			   "VHT AP is missing VHT capability/operation\n");
+		ret = false;
+		goto out;
 	}
 
 	mutex_lock(&sdata->local->sta_mtx);
@@ -2580,7 +2648,8 @@ static bool ieee80211_assoc_success(struct ieee80211_sub_if_data *sdata,
 	sta = sta_info_get(sdata, cbss->bssid);
 	if (WARN_ON(!sta)) {
 		mutex_unlock(&sdata->local->sta_mtx);
-		return false;
+		ret = false;
+		goto out;
 	}
 
 	sband = local->hw.wiphy->bands[ieee80211_get_sdata_band(sdata)];
@@ -2633,7 +2702,8 @@ static bool ieee80211_assoc_success(struct ieee80211_sub_if_data *sdata,
 			   sta->sta.addr);
 		WARN_ON(__sta_info_destroy(sta));
 		mutex_unlock(&sdata->local->sta_mtx);
-		return false;
+		ret = false;
+		goto out;
 	}
 
 	mutex_unlock(&sdata->local->sta_mtx);
@@ -2673,7 +2743,10 @@ static bool ieee80211_assoc_success(struct ieee80211_sub_if_data *sdata,
 	ieee80211_sta_rx_notify(sdata, (struct ieee80211_hdr *)mgmt);
 	ieee80211_sta_reset_beacon_monitor(sdata);
 
-	return true;
+	ret = true;
+ out:
+	kfree(bss_ies);
+	return ret;
 }
 
 static enum rx_mgmt_action __must_check

net/mac80211/util.c

@@ -661,12 +661,12 @@ void ieee80211_queue_delayed_work(struct ieee80211_hw *hw,
 }
 EXPORT_SYMBOL(ieee80211_queue_delayed_work);
 
-u32 ieee802_11_parse_elems_crc(u8 *start, size_t len, bool action,
+u32 ieee802_11_parse_elems_crc(const u8 *start, size_t len, bool action,
 			       struct ieee802_11_elems *elems,
 			       u64 filter, u32 crc)
 {
 	size_t left = len;
-	u8 *pos = start;
+	const u8 *pos = start;
 	bool calc_crc = filter != 0;
 	DECLARE_BITMAP(seen_elems, 256);
 	const u8 *ie;