Commit 4d36ec58 authored by Johannes Berg's avatar Johannes Berg Committed by John W. Linville
Browse files

mac80211: split hardware scan by band 



There's currently a very odd bug in mac80211 -- a
hardware scan that is done while the hardware is
really operating on 2.4 GHz will include CCK rates
in the probe request frame, even on 5 GHz (if the
driver uses the mac80211 IEs). Vice versa, if the
hardware is operating on 5 GHz the 2.4 GHz probe
requests will not include CCK rates even though
they should.

Fix this by splitting up cfg80211 scan requests by
band -- recalculating the IEs every time -- and
requesting only per-band scans from the driver.

Apparently this bug hasn't been a problem yet, but
it is imaginable that some older access points get
confused if confronted with such behaviour.

Signed-off-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent b59f04cb

net/mac80211/ieee80211_i.h

+4 −4
Original line number Diff line number Diff line
@@ -667,10 +667,9 @@ struct ieee80211_local { 
	unsigned long scanning;

	struct cfg80211_ssid scan_ssid;

	struct cfg80211_scan_request *int_scan_req;

	struct cfg80211_scan_request *scan_req;

	struct cfg80211_scan_request *scan_req, *hw_scan_req;

	struct ieee80211_channel *scan_channel;

	const u8 *orig_ies;

	int orig_ies_len;

	enum ieee80211_band hw_scan_band;

	int scan_channel_idx;

	int scan_ies_len;
@@ -1050,7 +1049,8 @@ void ieee80211_send_auth(struct ieee80211_sub_if_data *sdata, 
			 u8 *extra, size_t extra_len, const u8 *bssid,

			 const u8 *key, u8 key_len, u8 key_idx);

int ieee80211_build_preq_ies(struct ieee80211_local *local, u8 *buffer,

			     const u8 *ie, size_t ie_len);

			     const u8 *ie, size_t ie_len,

			     enum ieee80211_band band);

void ieee80211_send_probe_req(struct ieee80211_sub_if_data *sdata, u8 *dst,

			      const u8 *ssid, size_t ssid_len,

			      const u8 *ie, size_t ie_len);

net/mac80211/scan.c

+71 −25
Original line number Diff line number Diff line
@@ -187,6 +187,39 @@ ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb) 
	return RX_QUEUED;

}



/* return false if no more work */

static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)

{

	struct cfg80211_scan_request *req = local->scan_req;

	enum ieee80211_band band;

	int i, ielen, n_chans;



	do {

		if (local->hw_scan_band == IEEE80211_NUM_BANDS)

			return false;



		band = local->hw_scan_band;

		n_chans = 0;

		for (i = 0; i < req->n_channels; i++) {

			if (req->channels[i]->band == band) {

				local->hw_scan_req->channels[n_chans] =

							req->channels[i];

				n_chans++;

			}

		}



		local->hw_scan_band++;

	} while (!n_chans);



	local->hw_scan_req->n_channels = n_chans;



	ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,

					 req->ie, req->ie_len, band);

	local->hw_scan_req->ie_len = ielen;



	return true;

}



/*

 * inform AP that we will go to sleep so that it will buffer the frames

 * while we scan
@@ -247,13 +280,6 @@ static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata) 
	}

}



static void ieee80211_restore_scan_ies(struct ieee80211_local *local)

{

	kfree(local->scan_req->ie);

	local->scan_req->ie = local->orig_ies;

	local->scan_req->ie_len = local->orig_ies_len;

}



void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)

{

	struct ieee80211_local *local = hw_to_local(hw);
@@ -272,15 +298,22 @@ void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted) 
		return;

	}



	if (test_bit(SCAN_HW_SCANNING, &local->scanning))

		ieee80211_restore_scan_ies(local);

	was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);

	if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {

		ieee80211_queue_delayed_work(&local->hw,

					     &local->scan_work, 0);

		mutex_unlock(&local->scan_mtx);

		return;

	}



	kfree(local->hw_scan_req);

	local->hw_scan_req = NULL;



	if (local->scan_req != local->int_scan_req)

		cfg80211_scan_done(local->scan_req, aborted);

	local->scan_req = NULL;

	local->scan_sdata = NULL;



	was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);

	local->scanning = 0;

	local->scan_channel = NULL;
@@ -392,19 +425,23 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata, 


	if (local->ops->hw_scan) {

		u8 *ies;

		int ielen;



		ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +

			      local->scan_ies_len + req->ie_len, GFP_KERNEL);

		if (!ies)

		local->hw_scan_req = kmalloc(

				sizeof(*local->hw_scan_req) +

				req->n_channels * sizeof(req->channels[0]) +

				2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +

				req->ie_len, GFP_KERNEL);

		if (!local->hw_scan_req)

			return -ENOMEM;



		ielen = ieee80211_build_preq_ies(local, ies,

						 req->ie, req->ie_len);

		local->orig_ies = req->ie;

		local->orig_ies_len = req->ie_len;

		req->ie = ies;

		req->ie_len = ielen;

		local->hw_scan_req->ssids = req->ssids;

		local->hw_scan_req->n_ssids = req->n_ssids;

		ies = (u8 *)local->hw_scan_req +

			sizeof(*local->hw_scan_req) +

			req->n_channels * sizeof(req->channels[0]);

		local->hw_scan_req->ie = ies;



		local->hw_scan_band = 0;

	}



	local->scan_req = req;
@@ -436,16 +473,17 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata, 
	ieee80211_recalc_idle(local);

	mutex_unlock(&local->scan_mtx);



	if (local->ops->hw_scan)

		rc = drv_hw_scan(local, local->scan_req);

	else

	if (local->ops->hw_scan) {

		WARN_ON(!ieee80211_prep_hw_scan(local));

		rc = drv_hw_scan(local, local->hw_scan_req);

	} else

		rc = ieee80211_start_sw_scan(local);



	mutex_lock(&local->scan_mtx);



	if (rc) {

		if (local->ops->hw_scan)

			ieee80211_restore_scan_ies(local);

		kfree(local->hw_scan_req);

		local->hw_scan_req = NULL;

		local->scanning = 0;



		ieee80211_recalc_idle(local);
@@ -654,6 +692,14 @@ void ieee80211_scan_work(struct work_struct *work) 
		return;

	}



	if (local->hw_scan_req) {

		int rc = drv_hw_scan(local, local->hw_scan_req);

		mutex_unlock(&local->scan_mtx);

		if (rc)

			ieee80211_scan_completed(&local->hw, true);

		return;

	}



	if (local->scan_req && !local->scanning) {

		struct cfg80211_scan_request *req = local->scan_req;

		int rc;

net/mac80211/util.c

+5 −3
Original line number Diff line number Diff line
@@ -872,13 +872,14 @@ void ieee80211_send_auth(struct ieee80211_sub_if_data *sdata, 
}



int ieee80211_build_preq_ies(struct ieee80211_local *local, u8 *buffer,

			     const u8 *ie, size_t ie_len)

			     const u8 *ie, size_t ie_len,

			     enum ieee80211_band band)

{

	struct ieee80211_supported_band *sband;

	u8 *pos, *supp_rates_len, *esupp_rates_len = NULL;

	int i;



	sband = local->hw.wiphy->bands[local->hw.conf.channel->band];

	sband = local->hw.wiphy->bands[band];



	pos = buffer;
@@ -966,7 +967,8 @@ void ieee80211_send_probe_req(struct ieee80211_sub_if_data *sdata, u8 *dst, 
	memcpy(pos, ssid, ssid_len);

	pos += ssid_len;



	skb_put(skb, ieee80211_build_preq_ies(local, pos, ie, ie_len));

	skb_put(skb, ieee80211_build_preq_ies(local, pos, ie, ie_len,

					      local->hw.conf.channel->band));



	ieee80211_tx_skb(sdata, skb, 0);

}

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