wifi: mac80211: implement MLO multicast deduplication

If the vif is an MLD then it may receive multicast from
different links, and should drop those frames according
to the SN. Implement that.

Link: https://msgid.link/20240129200456.693b77d14b44.I491846f2bea0058c14eab6422962c10bfae9b675@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

include/linux/ieee80211.h

@@ -191,6 +191,11 @@ static inline bool ieee80211_sn_less(u16 sn1, u16 sn2)
 	return ((sn1 - sn2) & IEEE80211_SN_MASK) > (IEEE80211_SN_MODULO >> 1);
 }
 
+static inline bool ieee80211_sn_less_eq(u16 sn1, u16 sn2)
+{
+	return ((sn2 - sn1) & IEEE80211_SN_MASK) <= (IEEE80211_SN_MODULO >> 1);
+}
+
 static inline u16 ieee80211_sn_add(u16 sn1, u16 sn2)
 {
 	return (sn1 + sn2) & IEEE80211_SN_MASK;

net/mac80211/ieee80211_i.h

@@ -5,7 +5,7 @@
  * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
  * Copyright 2007-2010	Johannes Berg <johannes@sipsolutions.net>
  * Copyright 2013-2015  Intel Mobile Communications GmbH
- * Copyright (C) 2018-2022 Intel Corporation
+ * Copyright (C) 2018-2024 Intel Corporation
  */
 
 #ifndef IEEE80211_I_H
@@ -523,6 +523,8 @@ struct ieee80211_if_managed {
 
 	unsigned int flags;
 
+	u16 mcast_seq_last;
+
 	bool status_acked;
 	bool status_received;
 	__le16 status_fc;

net/mac80211/mlme.c

@@ -3351,6 +3351,8 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
 	wiphy_delayed_work_cancel(sdata->local->hw.wiphy,
 				  &ifmgd->neg_ttlm_timeout_work);
 	ieee80211_vif_set_links(sdata, 0, 0);
+
+	ifmgd->mcast_seq_last = IEEE80211_SN_MODULO;
 }
 
 static void ieee80211_reset_ap_probe(struct ieee80211_sub_if_data *sdata)
@@ -7512,6 +7514,7 @@ void ieee80211_sta_setup_sdata(struct ieee80211_sub_if_data *sdata)
 	spin_lock_init(&ifmgd->teardown_lock);
 	ifmgd->teardown_skb = NULL;
 	ifmgd->orig_teardown_skb = NULL;
+	ifmgd->mcast_seq_last = IEEE80211_SN_MODULO;
 }
 
 static void ieee80211_recalc_smps_work(struct wiphy *wiphy,

net/mac80211/rx.c

@@ -1434,13 +1434,31 @@ ieee80211_rx_h_check_dup(struct ieee80211_rx_data *rx)
 		return RX_CONTINUE;
 
 	if (ieee80211_is_ctl(hdr->frame_control) ||
-	    ieee80211_is_any_nullfunc(hdr->frame_control) ||
-	    is_multicast_ether_addr(hdr->addr1))
+	    ieee80211_is_any_nullfunc(hdr->frame_control))
 		return RX_CONTINUE;
 
 	if (!rx->sta)
 		return RX_CONTINUE;
 
+	if (unlikely(is_multicast_ether_addr(hdr->addr1))) {
+		struct ieee80211_sub_if_data *sdata = rx->sdata;
+		u16 sn = ieee80211_get_sn(hdr);
+
+		if (!ieee80211_is_data_present(hdr->frame_control))
+			return RX_CONTINUE;
+
+		if (!ieee80211_vif_is_mld(&sdata->vif) ||
+		    sdata->vif.type != NL80211_IFTYPE_STATION)
+			return RX_CONTINUE;
+
+		if (sdata->u.mgd.mcast_seq_last != IEEE80211_SN_MODULO &&
+		    ieee80211_sn_less_eq(sn, sdata->u.mgd.mcast_seq_last))
+			return RX_DROP_U_DUP;
+
+		sdata->u.mgd.mcast_seq_last = sn;
+		return RX_CONTINUE;
+	}
+
 	if (unlikely(ieee80211_has_retry(hdr->frame_control) &&
 		     rx->sta->last_seq_ctrl[rx->seqno_idx] == hdr->seq_ctrl)) {
 		I802_DEBUG_INC(rx->local->dot11FrameDuplicateCount);