Commit d524215f authored by Felix Fietkau's avatar Felix Fietkau Committed by John W. Linville
Browse files

mac80211: use nullfunc frames for 4-addr sta detection 



To detect incoming 4-addr stations, hostapd needs to receive a 4-addr
data frame from the remote station, so that it can create the AP VLAN
for it. With this patch, the mlme code emits a 4-addr nullfunc frame
immediately after assoc. On the AP side it also drops 4-addr nullfunc
frames to the cooked monitor mode interface, if the interface hasn't
been fully set up to receive 4-addr data frames yet.

Signed-off-by: default avatarFelix Fietkau <nbd@openwrt.org>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 199afd9d

net/mac80211/mlme.c

+39 −0
Original line number Diff line number Diff line
@@ -282,6 +282,38 @@ void ieee80211_send_nullfunc(struct ieee80211_local *local, 
	ieee80211_tx_skb(sdata, skb);

}



static void ieee80211_send_4addr_nullfunc(struct ieee80211_local *local,

					  struct ieee80211_sub_if_data *sdata)

{

	struct sk_buff *skb;

	struct ieee80211_hdr *nullfunc;

	__le16 fc;



	if (WARN_ON(sdata->vif.type != NL80211_IFTYPE_STATION))

		return;



	skb = dev_alloc_skb(local->hw.extra_tx_headroom + 30);

	if (!skb) {

		printk(KERN_DEBUG "%s: failed to allocate buffer for 4addr "

		       "nullfunc frame\n", sdata->name);

		return;

	}

	skb_reserve(skb, local->hw.extra_tx_headroom);



	nullfunc = (struct ieee80211_hdr *) skb_put(skb, 30);

	memset(nullfunc, 0, 30);

	fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_NULLFUNC |

			 IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS);

	nullfunc->frame_control = fc;

	memcpy(nullfunc->addr1, sdata->u.mgd.bssid, ETH_ALEN);

	memcpy(nullfunc->addr2, sdata->vif.addr, ETH_ALEN);

	memcpy(nullfunc->addr3, sdata->u.mgd.bssid, ETH_ALEN);

	memcpy(nullfunc->addr4, sdata->vif.addr, ETH_ALEN);



	IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT;

	ieee80211_tx_skb(sdata, skb);

}



/* spectrum management related things */

static void ieee80211_chswitch_work(struct work_struct *work)

{
@@ -1089,6 +1121,13 @@ static bool ieee80211_assoc_success(struct ieee80211_work *wk, 
	bss_conf->assoc_capability = capab_info;

	ieee80211_set_associated(sdata, cbss, changed);



	/*

	 * If we're using 4-addr mode, let the AP know that we're

	 * doing so, so that it can create the STA VLAN on its side

	 */

	if (ifmgd->use_4addr)

		ieee80211_send_4addr_nullfunc(local, sdata);



	/*

	 * Start timer to probe the connection to the AP now.

	 * Also start the timer that will detect beacon loss.

net/mac80211/rx.c

+12 −0
Original line number Diff line number Diff line
@@ -1111,6 +1111,18 @@ ieee80211_rx_h_sta_process(struct ieee80211_rx_data *rx) 
	if (ieee80211_is_nullfunc(hdr->frame_control) ||

	    ieee80211_is_qos_nullfunc(hdr->frame_control)) {

		I802_DEBUG_INC(rx->local->rx_handlers_drop_nullfunc);



		/*

		 * If we receive a 4-addr nullfunc frame from a STA

		 * that was not moved to a 4-addr STA vlan yet, drop

		 * the frame to the monitor interface, to make sure

		 * that hostapd sees it

		 */

		if (ieee80211_has_a4(hdr->frame_control) &&

		    (rx->sdata->vif.type == NL80211_IFTYPE_AP ||

		     (rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN &&

		      !rx->sdata->u.vlan.sta)))

			return RX_DROP_MONITOR;

		/*

		 * Update counter and free packet here to avoid

		 * counting this as a dropped packed.

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