Commit 9e478066 authored by Johannes Berg's avatar Johannes Berg
Browse files

mac80211: fix MU-MIMO follow-MAC mode 



There are two bugs in the follow-MAC code:
 * it treats the radiotap header as the 802.11 header
   (therefore it can't possibly work)
 * it doesn't verify that the skb data it accesses is actually
   present in the header, which is mitigated by the first point

Fix this by moving all of this out into a separate function.
This function copies the data it needs using skb_copy_bits()
to make sure it can be accessed if it's paged, and offsets
that by the possibly present vendor radiotap header.

This also makes all those conditions more readable.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent fc9c89b1

net/mac80211/rx.c

+47 −18
Original line number Diff line number Diff line
@@ -208,6 +208,51 @@ ieee80211_rx_radiotap_hdrlen(struct ieee80211_local *local, 
	return len;

}



static void ieee80211_handle_mu_mimo_mon(struct ieee80211_sub_if_data *sdata,

					 struct sk_buff *skb,

					 int rtap_vendor_space)

{

	struct {

		struct ieee80211_hdr_3addr hdr;

		u8 category;

		u8 action_code;

	} __packed action;



	if (!sdata)

		return;



	BUILD_BUG_ON(sizeof(action) != IEEE80211_MIN_ACTION_SIZE + 1);



	if (skb->len < rtap_vendor_space + sizeof(action) +

		       VHT_MUMIMO_GROUPS_DATA_LEN)

		return;



	if (!is_valid_ether_addr(sdata->u.mntr.mu_follow_addr))

		return;



	skb_copy_bits(skb, rtap_vendor_space, &action, sizeof(action));



	if (!ieee80211_is_action(action.hdr.frame_control))

		return;



	if (action.category != WLAN_CATEGORY_VHT)

		return;



	if (action.action_code != WLAN_VHT_ACTION_GROUPID_MGMT)

		return;



	if (!ether_addr_equal(action.hdr.addr1, sdata->u.mntr.mu_follow_addr))

		return;



	skb = skb_copy(skb, GFP_ATOMIC);

	if (!skb)

		return;



	skb->pkt_type = IEEE80211_SDATA_QUEUE_TYPE_FRAME;

	skb_queue_tail(&sdata->skb_queue, skb);

	ieee80211_queue_work(&sdata->local->hw, &sdata->work);

}



/*

 * ieee80211_add_rx_radiotap_header - add radiotap header

 *
@@ -515,7 +560,6 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb, 
	struct net_device *prev_dev = NULL;

	int present_fcs_len = 0;

	unsigned int rtap_vendor_space = 0;

	struct ieee80211_mgmt *mgmt;

	struct ieee80211_sub_if_data *monitor_sdata =

		rcu_dereference(local->monitor_sdata);
@@ -553,6 +597,8 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb, 
		return remove_monitor_info(local, origskb, rtap_vendor_space);

	}



	ieee80211_handle_mu_mimo_mon(monitor_sdata, origskb, rtap_vendor_space);



	/* room for the radiotap header based on driver features */

	rt_hdrlen = ieee80211_rx_radiotap_hdrlen(local, status, origskb);

	needed_headroom = rt_hdrlen - rtap_vendor_space;
@@ -618,23 +664,6 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb, 
		ieee80211_rx_stats(sdata->dev, skb->len);

	}



	mgmt = (void *)skb->data;

	if (monitor_sdata &&

	    skb->len >= IEEE80211_MIN_ACTION_SIZE + 1 + VHT_MUMIMO_GROUPS_DATA_LEN &&

	    ieee80211_is_action(mgmt->frame_control) &&

	    mgmt->u.action.category == WLAN_CATEGORY_VHT &&

	    mgmt->u.action.u.vht_group_notif.action_code == WLAN_VHT_ACTION_GROUPID_MGMT &&

	    is_valid_ether_addr(monitor_sdata->u.mntr.mu_follow_addr) &&

	    ether_addr_equal(mgmt->da, monitor_sdata->u.mntr.mu_follow_addr)) {

		struct sk_buff *mu_skb = skb_copy(skb, GFP_ATOMIC);



		if (mu_skb) {

			mu_skb->pkt_type = IEEE80211_SDATA_QUEUE_TYPE_FRAME;

			skb_queue_tail(&monitor_sdata->skb_queue, mu_skb);

			ieee80211_queue_work(&local->hw, &monitor_sdata->work);

		}

	}



	if (prev_dev) {

		skb->dev = prev_dev;

		netif_receive_skb(skb);

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