summaryrefslogtreecommitdiff
path: root/net/mac802154/scan.c
blob: 5c191bedd72c4440b4ddffdef8848c2011451e8b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
// SPDX-License-Identifier: GPL-2.0-only
/*
 * IEEE 802.15.4 scanning management
 *
 * Copyright (C) 2021 Qorvo US, Inc
 * Authors:
 *   - David Girault <david.girault@qorvo.com>
 *   - Miquel Raynal <miquel.raynal@bootlin.com>
 */

#include <linux/module.h>
#include <linux/rtnetlink.h>
#include <net/mac802154.h>

#include "ieee802154_i.h"
#include "driver-ops.h"
#include "../ieee802154/nl802154.h"

#define IEEE802154_BEACON_MHR_SZ 13
#define IEEE802154_BEACON_PL_SZ 4
#define IEEE802154_BEACON_SKB_SZ (IEEE802154_BEACON_MHR_SZ + \
				  IEEE802154_BEACON_PL_SZ)

/* mac802154_scan_cleanup_locked() must be called upon scan completion or abort.
 * - Completions are asynchronous, not locked by the rtnl and decided by the
 *   scan worker.
 * - Aborts are decided by userspace, and locked by the rtnl.
 *
 * Concurrent modifications to the PHY, the interfaces or the hardware is in
 * general prevented by the rtnl. So in most cases we don't need additional
 * protection.
 *
 * However, the scan worker get's triggered without anybody noticing and thus we
 * must ensure the presence of the devices as well as data consistency:
 * - The sub-interface and device driver module get both their reference
 *   counters incremented whenever we start a scan, so they cannot disappear
 *   during operation.
 * - Data consistency is achieved by the use of rcu protected pointers.
 */
static int mac802154_scan_cleanup_locked(struct ieee802154_local *local,
					 struct ieee802154_sub_if_data *sdata,
					 bool aborted)
{
	struct wpan_dev *wpan_dev = &sdata->wpan_dev;
	struct wpan_phy *wpan_phy = local->phy;
	struct cfg802154_scan_request *request;
	u8 arg;

	/* Prevent any further use of the scan request */
	clear_bit(IEEE802154_IS_SCANNING, &local->ongoing);
	cancel_delayed_work(&local->scan_work);
	request = rcu_replace_pointer(local->scan_req, NULL, 1);
	if (!request)
		return 0;
	kvfree_rcu_mightsleep(request);

	/* Advertize first, while we know the devices cannot be removed */
	if (aborted)
		arg = NL802154_SCAN_DONE_REASON_ABORTED;
	else
		arg = NL802154_SCAN_DONE_REASON_FINISHED;
	nl802154_scan_done(wpan_phy, wpan_dev, arg);

	/* Cleanup software stack */
	ieee802154_mlme_op_post(local);

	/* Set the hardware back in its original state */
	drv_set_channel(local, wpan_phy->current_page,
			wpan_phy->current_channel);
	ieee802154_configure_durations(wpan_phy, wpan_phy->current_page,
				       wpan_phy->current_channel);
	drv_stop(local);
	synchronize_net();
	sdata->required_filtering = sdata->iface_default_filtering;
	drv_start(local, sdata->required_filtering, &local->addr_filt);

	return 0;
}

int mac802154_abort_scan_locked(struct ieee802154_local *local,
				struct ieee802154_sub_if_data *sdata)
{
	ASSERT_RTNL();

	if (!mac802154_is_scanning(local))
		return -ESRCH;

	return mac802154_scan_cleanup_locked(local, sdata, true);
}

static unsigned int mac802154_scan_get_channel_time(u8 duration_order,
						    u8 symbol_duration)
{
	u64 base_super_frame_duration = (u64)symbol_duration *
		IEEE802154_SUPERFRAME_PERIOD * IEEE802154_SLOT_PERIOD;

	return usecs_to_jiffies(base_super_frame_duration *
				(BIT(duration_order) + 1));
}

static void mac802154_flush_queued_beacons(struct ieee802154_local *local)
{
	struct cfg802154_mac_pkt *mac_pkt, *tmp;

	list_for_each_entry_safe(mac_pkt, tmp, &local->rx_beacon_list, node) {
		list_del(&mac_pkt->node);
		kfree_skb(mac_pkt->skb);
		kfree(mac_pkt);
	}
}

static void
mac802154_scan_get_next_channel(struct ieee802154_local *local,
				struct cfg802154_scan_request *scan_req,
				u8 *channel)
{
	(*channel)++;
	*channel = find_next_bit((const unsigned long *)&scan_req->channels,
				 IEEE802154_MAX_CHANNEL + 1,
				 *channel);
}

static int mac802154_scan_find_next_chan(struct ieee802154_local *local,
					 struct cfg802154_scan_request *scan_req,
					 u8 page, u8 *channel)
{
	mac802154_scan_get_next_channel(local, scan_req, channel);
	if (*channel > IEEE802154_MAX_CHANNEL)
		return -EINVAL;

	return 0;
}

void mac802154_scan_worker(struct work_struct *work)
{
	struct ieee802154_local *local =
		container_of(work, struct ieee802154_local, scan_work.work);
	struct cfg802154_scan_request *scan_req;
	struct ieee802154_sub_if_data *sdata;
	unsigned int scan_duration = 0;
	struct wpan_phy *wpan_phy;
	u8 scan_req_duration;
	u8 page, channel;
	int ret;

	/* Ensure the device receiver is turned off when changing channels
	 * because there is no atomic way to change the channel and know on
	 * which one a beacon might have been received.
	 */
	drv_stop(local);
	synchronize_net();
	mac802154_flush_queued_beacons(local);

	rcu_read_lock();
	scan_req = rcu_dereference(local->scan_req);
	if (unlikely(!scan_req)) {
		rcu_read_unlock();
		return;
	}

	sdata = IEEE802154_WPAN_DEV_TO_SUB_IF(scan_req->wpan_dev);

	/* Wait an arbitrary amount of time in case we cannot use the device */
	if (local->suspended || !ieee802154_sdata_running(sdata)) {
		rcu_read_unlock();
		queue_delayed_work(local->mac_wq, &local->scan_work,
				   msecs_to_jiffies(1000));
		return;
	}

	wpan_phy = scan_req->wpan_phy;
	scan_req_duration = scan_req->duration;

	/* Look for the next valid chan */
	page = local->scan_page;
	channel = local->scan_channel;
	do {
		ret = mac802154_scan_find_next_chan(local, scan_req, page, &channel);
		if (ret) {
			rcu_read_unlock();
			goto end_scan;
		}
	} while (!ieee802154_chan_is_valid(scan_req->wpan_phy, page, channel));

	rcu_read_unlock();

	/* Bypass the stack on purpose when changing the channel */
	rtnl_lock();
	ret = drv_set_channel(local, page, channel);
	rtnl_unlock();
	if (ret) {
		dev_err(&sdata->dev->dev,
			"Channel change failure during scan, aborting (%d)\n", ret);
		goto end_scan;
	}

	local->scan_page = page;
	local->scan_channel = channel;

	rtnl_lock();
	ret = drv_start(local, IEEE802154_FILTERING_3_SCAN, &local->addr_filt);
	rtnl_unlock();
	if (ret) {
		dev_err(&sdata->dev->dev,
			"Restarting failure after channel change, aborting (%d)\n", ret);
		goto end_scan;
	}

	ieee802154_configure_durations(wpan_phy, page, channel);
	scan_duration = mac802154_scan_get_channel_time(scan_req_duration,
							wpan_phy->symbol_duration);
	dev_dbg(&sdata->dev->dev,
		"Scan page %u channel %u for %ums\n",
		page, channel, jiffies_to_msecs(scan_duration));
	queue_delayed_work(local->mac_wq, &local->scan_work, scan_duration);
	return;

end_scan:
	rtnl_lock();
	mac802154_scan_cleanup_locked(local, sdata, false);
	rtnl_unlock();
}

int mac802154_trigger_scan_locked(struct ieee802154_sub_if_data *sdata,
				  struct cfg802154_scan_request *request)
{
	struct ieee802154_local *local = sdata->local;

	ASSERT_RTNL();

	if (mac802154_is_scanning(local))
		return -EBUSY;

	/* TODO: support other scanning type */
	if (request->type != NL802154_SCAN_PASSIVE)
		return -EOPNOTSUPP;

	/* Store scanning parameters */
	rcu_assign_pointer(local->scan_req, request);

	/* Software scanning requires to set promiscuous mode, so we need to
	 * pause the Tx queue during the entire operation.
	 */
	ieee802154_mlme_op_pre(local);

	sdata->required_filtering = IEEE802154_FILTERING_3_SCAN;
	local->scan_page = request->page;
	local->scan_channel = -1;
	set_bit(IEEE802154_IS_SCANNING, &local->ongoing);

	nl802154_scan_started(request->wpan_phy, request->wpan_dev);

	queue_delayed_work(local->mac_wq, &local->scan_work, 0);

	return 0;
}

int mac802154_process_beacon(struct ieee802154_local *local,
			     struct sk_buff *skb,
			     u8 page, u8 channel)
{
	struct ieee802154_beacon_hdr *bh = (void *)skb->data;
	struct ieee802154_addr *src = &mac_cb(skb)->source;
	struct cfg802154_scan_request *scan_req;
	struct ieee802154_coord_desc desc;

	if (skb->len != sizeof(*bh))
		return -EINVAL;

	if (unlikely(src->mode == IEEE802154_ADDR_NONE))
		return -EINVAL;

	dev_dbg(&skb->dev->dev,
		"BEACON received on page %u channel %u\n",
		page, channel);

	memcpy(&desc.addr, src, sizeof(desc.addr));
	desc.page = page;
	desc.channel = channel;
	desc.link_quality = mac_cb(skb)->lqi;
	desc.superframe_spec = get_unaligned_le16(skb->data);
	desc.gts_permit = bh->gts_permit;

	trace_802154_scan_event(&desc);

	rcu_read_lock();
	scan_req = rcu_dereference(local->scan_req);
	if (likely(scan_req))
		nl802154_scan_event(scan_req->wpan_phy, scan_req->wpan_dev, &desc);
	rcu_read_unlock();

	return 0;
}

static int mac802154_transmit_beacon(struct ieee802154_local *local,
				     struct wpan_dev *wpan_dev)
{
	struct cfg802154_beacon_request *beacon_req;
	struct ieee802154_sub_if_data *sdata;
	struct sk_buff *skb;
	int ret;

	/* Update the sequence number */
	local->beacon.mhr.seq = atomic_inc_return(&wpan_dev->bsn) & 0xFF;

	skb = alloc_skb(IEEE802154_BEACON_SKB_SZ, GFP_KERNEL);
	if (!skb)
		return -ENOBUFS;

	rcu_read_lock();
	beacon_req = rcu_dereference(local->beacon_req);
	if (unlikely(!beacon_req)) {
		rcu_read_unlock();
		kfree_skb(skb);
		return -EINVAL;
	}

	sdata = IEEE802154_WPAN_DEV_TO_SUB_IF(beacon_req->wpan_dev);
	skb->dev = sdata->dev;

	rcu_read_unlock();

	ret = ieee802154_beacon_push(skb, &local->beacon);
	if (ret) {
		kfree_skb(skb);
		return ret;
	}

	/* Using the MLME transmission helper for sending beacons is a bit
	 * overkill because we do not really care about the final outcome.
	 *
	 * Even though, going through the whole net stack with a regular
	 * dev_queue_xmit() is not relevant either because we want beacons to be
	 * sent "now" rather than go through the whole net stack scheduling
	 * (qdisc & co).
	 *
	 * Finally, using ieee802154_subif_start_xmit() would only be an option
	 * if we had a generic transmit helper which would acquire the
	 * HARD_TX_LOCK() to prevent buffer handling conflicts with regular
	 * packets.
	 *
	 * So for now we keep it simple and send beacons with our MLME helper,
	 * even if it stops the ieee802154 queue entirely during these
	 * transmissions, wich anyway does not have a huge impact on the
	 * performances given the current design of the stack.
	 */
	return ieee802154_mlme_tx(local, sdata, skb);
}

void mac802154_beacon_worker(struct work_struct *work)
{
	struct ieee802154_local *local =
		container_of(work, struct ieee802154_local, beacon_work.work);
	struct cfg802154_beacon_request *beacon_req;
	struct ieee802154_sub_if_data *sdata;
	struct wpan_dev *wpan_dev;
	int ret;

	rcu_read_lock();
	beacon_req = rcu_dereference(local->beacon_req);
	if (unlikely(!beacon_req)) {
		rcu_read_unlock();
		return;
	}

	sdata = IEEE802154_WPAN_DEV_TO_SUB_IF(beacon_req->wpan_dev);

	/* Wait an arbitrary amount of time in case we cannot use the device */
	if (local->suspended || !ieee802154_sdata_running(sdata)) {
		rcu_read_unlock();
		queue_delayed_work(local->mac_wq, &local->beacon_work,
				   msecs_to_jiffies(1000));
		return;
	}

	wpan_dev = beacon_req->wpan_dev;

	rcu_read_unlock();

	dev_dbg(&sdata->dev->dev, "Sending beacon\n");
	ret = mac802154_transmit_beacon(local, wpan_dev);
	if (ret)
		dev_err(&sdata->dev->dev,
			"Beacon could not be transmitted (%d)\n", ret);

	queue_delayed_work(local->mac_wq, &local->beacon_work,
			   local->beacon_interval);
}

int mac802154_stop_beacons_locked(struct ieee802154_local *local,
				  struct ieee802154_sub_if_data *sdata)
{
	struct wpan_dev *wpan_dev = &sdata->wpan_dev;
	struct cfg802154_beacon_request *request;

	ASSERT_RTNL();

	if (!mac802154_is_beaconing(local))
		return -ESRCH;

	clear_bit(IEEE802154_IS_BEACONING, &local->ongoing);
	cancel_delayed_work(&local->beacon_work);
	request = rcu_replace_pointer(local->beacon_req, NULL, 1);
	if (!request)
		return 0;
	kvfree_rcu_mightsleep(request);

	nl802154_beaconing_done(wpan_dev);

	return 0;
}

int mac802154_send_beacons_locked(struct ieee802154_sub_if_data *sdata,
				  struct cfg802154_beacon_request *request)
{
	struct ieee802154_local *local = sdata->local;

	ASSERT_RTNL();

	if (mac802154_is_beaconing(local))
		mac802154_stop_beacons_locked(local, sdata);

	/* Store beaconing parameters */
	rcu_assign_pointer(local->beacon_req, request);

	set_bit(IEEE802154_IS_BEACONING, &local->ongoing);

	memset(&local->beacon, 0, sizeof(local->beacon));
	local->beacon.mhr.fc.type = IEEE802154_FC_TYPE_BEACON;
	local->beacon.mhr.fc.security_enabled = 0;
	local->beacon.mhr.fc.frame_pending = 0;
	local->beacon.mhr.fc.ack_request = 0;
	local->beacon.mhr.fc.intra_pan = 0;
	local->beacon.mhr.fc.dest_addr_mode = IEEE802154_NO_ADDRESSING;
	local->beacon.mhr.fc.version = IEEE802154_2003_STD;
	local->beacon.mhr.fc.source_addr_mode = IEEE802154_EXTENDED_ADDRESSING;
	atomic_set(&request->wpan_dev->bsn, -1);
	local->beacon.mhr.source.mode = IEEE802154_ADDR_LONG;
	local->beacon.mhr.source.pan_id = request->wpan_dev->pan_id;
	local->beacon.mhr.source.extended_addr = request->wpan_dev->extended_addr;
	local->beacon.mac_pl.beacon_order = request->interval;
	local->beacon.mac_pl.superframe_order = request->interval;
	local->beacon.mac_pl.final_cap_slot = 0xf;
	local->beacon.mac_pl.battery_life_ext = 0;
	/* TODO: Fill this field depending on the coordinator capacity */
	local->beacon.mac_pl.pan_coordinator = 1;
	local->beacon.mac_pl.assoc_permit = 1;

	/* Start the beacon work */
	local->beacon_interval =
		mac802154_scan_get_channel_time(request->interval,
						request->wpan_phy->symbol_duration);
	queue_delayed_work(local->mac_wq, &local->beacon_work, 0);

	return 0;
}