summaryrefslogtreecommitdiff
path: root/drivers/net/wireless/virt_wifi.c
blob: 514f2c1124b618c472f99fd6bb17e1a8bd1ba654 (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
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
// SPDX-License-Identifier: GPL-2.0
/* drivers/net/wireless/virt_wifi.c
 *
 * A fake implementation of cfg80211_ops that can be tacked on to an ethernet
 * net_device to make it appear as a wireless connection.
 *
 * Copyright (C) 2018 Google, Inc.
 *
 * Author: schuffelen@google.com
 */

#include <net/cfg80211.h>
#include <net/rtnetlink.h>
#include <linux/etherdevice.h>
#include <linux/math64.h>
#include <linux/module.h>

static struct wiphy *common_wiphy;

struct virt_wifi_wiphy_priv {
	struct delayed_work scan_result;
	struct cfg80211_scan_request *scan_request;
	bool being_deleted;
};

static struct ieee80211_channel channel_2ghz = {
	.band = NL80211_BAND_2GHZ,
	.center_freq = 2432,
	.hw_value = 2432,
	.max_power = 20,
};

static struct ieee80211_rate bitrates_2ghz[] = {
	{ .bitrate = 10 },
	{ .bitrate = 20 },
	{ .bitrate = 55 },
	{ .bitrate = 110 },
	{ .bitrate = 60 },
	{ .bitrate = 120 },
	{ .bitrate = 240 },
};

static struct ieee80211_supported_band band_2ghz = {
	.channels = &channel_2ghz,
	.bitrates = bitrates_2ghz,
	.band = NL80211_BAND_2GHZ,
	.n_channels = 1,
	.n_bitrates = ARRAY_SIZE(bitrates_2ghz),
	.ht_cap = {
		.ht_supported = true,
		.cap = IEEE80211_HT_CAP_SUP_WIDTH_20_40 |
		       IEEE80211_HT_CAP_GRN_FLD |
		       IEEE80211_HT_CAP_SGI_20 |
		       IEEE80211_HT_CAP_SGI_40 |
		       IEEE80211_HT_CAP_DSSSCCK40,
		.ampdu_factor = 0x3,
		.ampdu_density = 0x6,
		.mcs = {
			.rx_mask = {0xff, 0xff},
			.tx_params = IEEE80211_HT_MCS_TX_DEFINED,
		},
	},
};

static struct ieee80211_channel channel_5ghz = {
	.band = NL80211_BAND_5GHZ,
	.center_freq = 5240,
	.hw_value = 5240,
	.max_power = 20,
};

static struct ieee80211_rate bitrates_5ghz[] = {
	{ .bitrate = 60 },
	{ .bitrate = 120 },
	{ .bitrate = 240 },
};

#define RX_MCS_MAP (IEEE80211_VHT_MCS_SUPPORT_0_9 << 0 | \
		    IEEE80211_VHT_MCS_SUPPORT_0_9 << 2 | \
		    IEEE80211_VHT_MCS_SUPPORT_0_9 << 4 | \
		    IEEE80211_VHT_MCS_SUPPORT_0_9 << 6 | \
		    IEEE80211_VHT_MCS_SUPPORT_0_9 << 8 | \
		    IEEE80211_VHT_MCS_SUPPORT_0_9 << 10 | \
		    IEEE80211_VHT_MCS_SUPPORT_0_9 << 12 | \
		    IEEE80211_VHT_MCS_SUPPORT_0_9 << 14)

#define TX_MCS_MAP (IEEE80211_VHT_MCS_SUPPORT_0_9 << 0 | \
		    IEEE80211_VHT_MCS_SUPPORT_0_9 << 2 | \
		    IEEE80211_VHT_MCS_SUPPORT_0_9 << 4 | \
		    IEEE80211_VHT_MCS_SUPPORT_0_9 << 6 | \
		    IEEE80211_VHT_MCS_SUPPORT_0_9 << 8 | \
		    IEEE80211_VHT_MCS_SUPPORT_0_9 << 10 | \
		    IEEE80211_VHT_MCS_SUPPORT_0_9 << 12 | \
		    IEEE80211_VHT_MCS_SUPPORT_0_9 << 14)

static struct ieee80211_supported_band band_5ghz = {
	.channels = &channel_5ghz,
	.bitrates = bitrates_5ghz,
	.band = NL80211_BAND_5GHZ,
	.n_channels = 1,
	.n_bitrates = ARRAY_SIZE(bitrates_5ghz),
	.ht_cap = {
		.ht_supported = true,
		.cap = IEEE80211_HT_CAP_SUP_WIDTH_20_40 |
		       IEEE80211_HT_CAP_GRN_FLD |
		       IEEE80211_HT_CAP_SGI_20 |
		       IEEE80211_HT_CAP_SGI_40 |
		       IEEE80211_HT_CAP_DSSSCCK40,
		.ampdu_factor = 0x3,
		.ampdu_density = 0x6,
		.mcs = {
			.rx_mask = {0xff, 0xff},
			.tx_params = IEEE80211_HT_MCS_TX_DEFINED,
		},
	},
	.vht_cap = {
		.vht_supported = true,
		.cap = IEEE80211_VHT_CAP_MAX_MPDU_LENGTH_11454 |
		       IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ |
		       IEEE80211_VHT_CAP_RXLDPC |
		       IEEE80211_VHT_CAP_SHORT_GI_80 |
		       IEEE80211_VHT_CAP_SHORT_GI_160 |
		       IEEE80211_VHT_CAP_TXSTBC |
		       IEEE80211_VHT_CAP_RXSTBC_1 |
		       IEEE80211_VHT_CAP_RXSTBC_2 |
		       IEEE80211_VHT_CAP_RXSTBC_3 |
		       IEEE80211_VHT_CAP_RXSTBC_4 |
		       IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_MASK,
		.vht_mcs = {
			.rx_mcs_map = cpu_to_le16(RX_MCS_MAP),
			.tx_mcs_map = cpu_to_le16(TX_MCS_MAP),
		}
	},
};

/* Assigned at module init. Guaranteed locally-administered and unicast. */
static u8 fake_router_bssid[ETH_ALEN] __ro_after_init = {};

static void virt_wifi_inform_bss(struct wiphy *wiphy)
{
	u64 tsf = div_u64(ktime_get_boottime_ns(), 1000);
	struct cfg80211_bss *informed_bss;
	static const struct {
		u8 tag;
		u8 len;
		u8 ssid[8];
	} __packed ssid = {
		.tag = WLAN_EID_SSID,
		.len = 8,
		.ssid = "VirtWifi",
	};

	informed_bss = cfg80211_inform_bss(wiphy, &channel_5ghz,
					   CFG80211_BSS_FTYPE_PRESP,
					   fake_router_bssid, tsf,
					   WLAN_CAPABILITY_ESS, 0,
					   (void *)&ssid, sizeof(ssid),
					   DBM_TO_MBM(-50), GFP_KERNEL);
	cfg80211_put_bss(wiphy, informed_bss);
}

/* Called with the rtnl lock held. */
static int virt_wifi_scan(struct wiphy *wiphy,
			  struct cfg80211_scan_request *request)
{
	struct virt_wifi_wiphy_priv *priv = wiphy_priv(wiphy);

	wiphy_debug(wiphy, "scan\n");

	if (priv->scan_request || priv->being_deleted)
		return -EBUSY;

	priv->scan_request = request;
	schedule_delayed_work(&priv->scan_result, HZ * 2);

	return 0;
}

/* Acquires and releases the rdev BSS lock. */
static void virt_wifi_scan_result(struct work_struct *work)
{
	struct virt_wifi_wiphy_priv *priv =
		container_of(work, struct virt_wifi_wiphy_priv,
			     scan_result.work);
	struct wiphy *wiphy = priv_to_wiphy(priv);
	struct cfg80211_scan_info scan_info = { .aborted = false };

	virt_wifi_inform_bss(wiphy);

	/* Schedules work which acquires and releases the rtnl lock. */
	cfg80211_scan_done(priv->scan_request, &scan_info);
	priv->scan_request = NULL;
}

/* May acquire and release the rdev BSS lock. */
static void virt_wifi_cancel_scan(struct wiphy *wiphy)
{
	struct virt_wifi_wiphy_priv *priv = wiphy_priv(wiphy);

	cancel_delayed_work_sync(&priv->scan_result);
	/* Clean up dangling callbacks if necessary. */
	if (priv->scan_request) {
		struct cfg80211_scan_info scan_info = { .aborted = true };
		/* Schedules work which acquires and releases the rtnl lock. */
		cfg80211_scan_done(priv->scan_request, &scan_info);
		priv->scan_request = NULL;
	}
}

struct virt_wifi_netdev_priv {
	struct delayed_work connect;
	struct net_device *lowerdev;
	struct net_device *upperdev;
	u32 tx_packets;
	u32 tx_failed;
	u8 connect_requested_bss[ETH_ALEN];
	bool is_up;
	bool is_connected;
	bool being_deleted;
};

/* Called with the rtnl lock held. */
static int virt_wifi_connect(struct wiphy *wiphy, struct net_device *netdev,
			     struct cfg80211_connect_params *sme)
{
	struct virt_wifi_netdev_priv *priv = netdev_priv(netdev);
	bool could_schedule;

	if (priv->being_deleted || !priv->is_up)
		return -EBUSY;

	could_schedule = schedule_delayed_work(&priv->connect, HZ * 2);
	if (!could_schedule)
		return -EBUSY;

	if (sme->bssid) {
		ether_addr_copy(priv->connect_requested_bss, sme->bssid);
	} else {
		virt_wifi_inform_bss(wiphy);
		eth_zero_addr(priv->connect_requested_bss);
	}

	wiphy_debug(wiphy, "connect\n");

	return 0;
}

/* Acquires and releases the rdev event lock. */
static void virt_wifi_connect_complete(struct work_struct *work)
{
	struct virt_wifi_netdev_priv *priv =
		container_of(work, struct virt_wifi_netdev_priv, connect.work);
	u8 *requested_bss = priv->connect_requested_bss;
	bool right_addr = ether_addr_equal(requested_bss, fake_router_bssid);
	u16 status = WLAN_STATUS_SUCCESS;

	if (is_zero_ether_addr(requested_bss))
		requested_bss = NULL;

	if (!priv->is_up || (requested_bss && !right_addr))
		status = WLAN_STATUS_UNSPECIFIED_FAILURE;
	else
		priv->is_connected = true;

	/* Schedules an event that acquires the rtnl lock. */
	cfg80211_connect_result(priv->upperdev, requested_bss, NULL, 0, NULL, 0,
				status, GFP_KERNEL);
	netif_carrier_on(priv->upperdev);
}

/* May acquire and release the rdev event lock. */
static void virt_wifi_cancel_connect(struct net_device *netdev)
{
	struct virt_wifi_netdev_priv *priv = netdev_priv(netdev);

	/* If there is work pending, clean up dangling callbacks. */
	if (cancel_delayed_work_sync(&priv->connect)) {
		/* Schedules an event that acquires the rtnl lock. */
		cfg80211_connect_result(priv->upperdev,
					priv->connect_requested_bss, NULL, 0,
					NULL, 0,
					WLAN_STATUS_UNSPECIFIED_FAILURE,
					GFP_KERNEL);
	}
}

/* Called with the rtnl lock held. Acquires the rdev event lock. */
static int virt_wifi_disconnect(struct wiphy *wiphy, struct net_device *netdev,
				u16 reason_code)
{
	struct virt_wifi_netdev_priv *priv = netdev_priv(netdev);

	if (priv->being_deleted)
		return -EBUSY;

	wiphy_debug(wiphy, "disconnect\n");
	virt_wifi_cancel_connect(netdev);

	cfg80211_disconnected(netdev, reason_code, NULL, 0, true, GFP_KERNEL);
	priv->is_connected = false;
	netif_carrier_off(netdev);

	return 0;
}

/* Called with the rtnl lock held. */
static int virt_wifi_get_station(struct wiphy *wiphy, struct net_device *dev,
				 const u8 *mac, struct station_info *sinfo)
{
	struct virt_wifi_netdev_priv *priv = netdev_priv(dev);

	wiphy_debug(wiphy, "get_station\n");

	if (!priv->is_connected || !ether_addr_equal(mac, fake_router_bssid))
		return -ENOENT;

	sinfo->filled = BIT_ULL(NL80211_STA_INFO_TX_PACKETS) |
		BIT_ULL(NL80211_STA_INFO_TX_FAILED) |
		BIT_ULL(NL80211_STA_INFO_SIGNAL) |
		BIT_ULL(NL80211_STA_INFO_TX_BITRATE);
	sinfo->tx_packets = priv->tx_packets;
	sinfo->tx_failed = priv->tx_failed;
	/* For CFG80211_SIGNAL_TYPE_MBM, value is expressed in _dBm_ */
	sinfo->signal = -50;
	sinfo->txrate = (struct rate_info) {
		.legacy = 10, /* units are 100kbit/s */
	};
	return 0;
}

/* Called with the rtnl lock held. */
static int virt_wifi_dump_station(struct wiphy *wiphy, struct net_device *dev,
				  int idx, u8 *mac, struct station_info *sinfo)
{
	struct virt_wifi_netdev_priv *priv = netdev_priv(dev);

	wiphy_debug(wiphy, "dump_station\n");

	if (idx != 0 || !priv->is_connected)
		return -ENOENT;

	ether_addr_copy(mac, fake_router_bssid);
	return virt_wifi_get_station(wiphy, dev, fake_router_bssid, sinfo);
}

static const struct cfg80211_ops virt_wifi_cfg80211_ops = {
	.scan = virt_wifi_scan,

	.connect = virt_wifi_connect,
	.disconnect = virt_wifi_disconnect,

	.get_station = virt_wifi_get_station,
	.dump_station = virt_wifi_dump_station,
};

/* Acquires and releases the rtnl lock. */
static struct wiphy *virt_wifi_make_wiphy(void)
{
	struct wiphy *wiphy;
	struct virt_wifi_wiphy_priv *priv;
	int err;

	wiphy = wiphy_new(&virt_wifi_cfg80211_ops, sizeof(*priv));

	if (!wiphy)
		return NULL;

	wiphy->max_scan_ssids = 4;
	wiphy->max_scan_ie_len = 1000;
	wiphy->signal_type = CFG80211_SIGNAL_TYPE_MBM;

	wiphy->bands[NL80211_BAND_2GHZ] = &band_2ghz;
	wiphy->bands[NL80211_BAND_5GHZ] = &band_5ghz;
	wiphy->bands[NL80211_BAND_60GHZ] = NULL;

	wiphy->interface_modes = BIT(NL80211_IFTYPE_STATION);

	priv = wiphy_priv(wiphy);
	priv->being_deleted = false;
	priv->scan_request = NULL;
	INIT_DELAYED_WORK(&priv->scan_result, virt_wifi_scan_result);

	err = wiphy_register(wiphy);
	if (err < 0) {
		wiphy_free(wiphy);
		return NULL;
	}

	return wiphy;
}

/* Acquires and releases the rtnl lock. */
static void virt_wifi_destroy_wiphy(struct wiphy *wiphy)
{
	struct virt_wifi_wiphy_priv *priv;

	WARN(!wiphy, "%s called with null wiphy", __func__);
	if (!wiphy)
		return;

	priv = wiphy_priv(wiphy);
	priv->being_deleted = true;
	virt_wifi_cancel_scan(wiphy);

	if (wiphy->registered)
		wiphy_unregister(wiphy);
	wiphy_free(wiphy);
}

/* Enters and exits a RCU-bh critical section. */
static netdev_tx_t virt_wifi_start_xmit(struct sk_buff *skb,
					struct net_device *dev)
{
	struct virt_wifi_netdev_priv *priv = netdev_priv(dev);

	priv->tx_packets++;
	if (!priv->is_connected) {
		priv->tx_failed++;
		return NET_XMIT_DROP;
	}

	skb->dev = priv->lowerdev;
	return dev_queue_xmit(skb);
}

/* Called with rtnl lock held. */
static int virt_wifi_net_device_open(struct net_device *dev)
{
	struct virt_wifi_netdev_priv *priv = netdev_priv(dev);

	priv->is_up = true;
	return 0;
}

/* Called with rtnl lock held. */
static int virt_wifi_net_device_stop(struct net_device *dev)
{
	struct virt_wifi_netdev_priv *n_priv = netdev_priv(dev);

	n_priv->is_up = false;

	if (!dev->ieee80211_ptr)
		return 0;

	virt_wifi_cancel_scan(dev->ieee80211_ptr->wiphy);
	virt_wifi_cancel_connect(dev);
	netif_carrier_off(dev);

	return 0;
}

static int virt_wifi_net_device_get_iflink(const struct net_device *dev)
{
	struct virt_wifi_netdev_priv *priv = netdev_priv(dev);

	return priv->lowerdev->ifindex;
}

static const struct net_device_ops virt_wifi_ops = {
	.ndo_start_xmit = virt_wifi_start_xmit,
	.ndo_open	= virt_wifi_net_device_open,
	.ndo_stop	= virt_wifi_net_device_stop,
	.ndo_get_iflink = virt_wifi_net_device_get_iflink,
};

/* Invoked as part of rtnl lock release. */
static void virt_wifi_net_device_destructor(struct net_device *dev)
{
	/* Delayed past dellink to allow nl80211 to react to the device being
	 * deleted.
	 */
	kfree(dev->ieee80211_ptr);
	dev->ieee80211_ptr = NULL;
}

/* No lock interaction. */
static void virt_wifi_setup(struct net_device *dev)
{
	ether_setup(dev);
	dev->netdev_ops = &virt_wifi_ops;
	dev->needs_free_netdev  = true;
}

/* Called in a RCU read critical section from netif_receive_skb */
static rx_handler_result_t virt_wifi_rx_handler(struct sk_buff **pskb)
{
	struct sk_buff *skb = *pskb;
	struct virt_wifi_netdev_priv *priv =
		rcu_dereference(skb->dev->rx_handler_data);

	if (!priv->is_connected)
		return RX_HANDLER_PASS;

	/* GFP_ATOMIC because this is a packet interrupt handler. */
	skb = skb_share_check(skb, GFP_ATOMIC);
	if (!skb) {
		dev_err(&priv->upperdev->dev, "can't skb_share_check\n");
		return RX_HANDLER_CONSUMED;
	}

	*pskb = skb;
	skb->dev = priv->upperdev;
	skb->pkt_type = PACKET_HOST;
	return RX_HANDLER_ANOTHER;
}

/* Called with rtnl lock held. */
static int virt_wifi_newlink(struct net *src_net, struct net_device *dev,
			     struct nlattr *tb[], struct nlattr *data[],
			     struct netlink_ext_ack *extack)
{
	struct virt_wifi_netdev_priv *priv = netdev_priv(dev);
	int err;

	if (!tb[IFLA_LINK])
		return -EINVAL;

	netif_carrier_off(dev);

	priv->upperdev = dev;
	priv->lowerdev = __dev_get_by_index(src_net,
					    nla_get_u32(tb[IFLA_LINK]));

	if (!priv->lowerdev)
		return -ENODEV;
	if (!tb[IFLA_MTU])
		dev->mtu = priv->lowerdev->mtu;
	else if (dev->mtu > priv->lowerdev->mtu)
		return -EINVAL;

	err = netdev_rx_handler_register(priv->lowerdev, virt_wifi_rx_handler,
					 priv);
	if (err) {
		dev_err(&priv->lowerdev->dev,
			"can't netdev_rx_handler_register: %d\n", err);
		return err;
	}

	eth_hw_addr_inherit(dev, priv->lowerdev);
	netif_stacked_transfer_operstate(priv->lowerdev, dev);

	SET_NETDEV_DEV(dev, &priv->lowerdev->dev);
	dev->ieee80211_ptr = kzalloc(sizeof(*dev->ieee80211_ptr), GFP_KERNEL);

	if (!dev->ieee80211_ptr) {
		err = -ENOMEM;
		goto remove_handler;
	}

	dev->ieee80211_ptr->iftype = NL80211_IFTYPE_STATION;
	dev->ieee80211_ptr->wiphy = common_wiphy;

	err = register_netdevice(dev);
	if (err) {
		dev_err(&priv->lowerdev->dev, "can't register_netdevice: %d\n",
			err);
		goto free_wireless_dev;
	}

	err = netdev_upper_dev_link(priv->lowerdev, dev, extack);
	if (err) {
		dev_err(&priv->lowerdev->dev, "can't netdev_upper_dev_link: %d\n",
			err);
		goto unregister_netdev;
	}

	dev->priv_destructor = virt_wifi_net_device_destructor;
	priv->being_deleted = false;
	priv->is_connected = false;
	priv->is_up = false;
	INIT_DELAYED_WORK(&priv->connect, virt_wifi_connect_complete);
	__module_get(THIS_MODULE);

	return 0;
unregister_netdev:
	unregister_netdevice(dev);
free_wireless_dev:
	kfree(dev->ieee80211_ptr);
	dev->ieee80211_ptr = NULL;
remove_handler:
	netdev_rx_handler_unregister(priv->lowerdev);

	return err;
}

/* Called with rtnl lock held. */
static void virt_wifi_dellink(struct net_device *dev,
			      struct list_head *head)
{
	struct virt_wifi_netdev_priv *priv = netdev_priv(dev);

	if (dev->ieee80211_ptr)
		virt_wifi_cancel_scan(dev->ieee80211_ptr->wiphy);

	priv->being_deleted = true;
	virt_wifi_cancel_connect(dev);
	netif_carrier_off(dev);

	netdev_rx_handler_unregister(priv->lowerdev);
	netdev_upper_dev_unlink(priv->lowerdev, dev);

	unregister_netdevice_queue(dev, head);
	module_put(THIS_MODULE);

	/* Deleting the wiphy is handled in the module destructor. */
}

static struct rtnl_link_ops virt_wifi_link_ops = {
	.kind		= "virt_wifi",
	.setup		= virt_wifi_setup,
	.newlink	= virt_wifi_newlink,
	.dellink	= virt_wifi_dellink,
	.priv_size	= sizeof(struct virt_wifi_netdev_priv),
};

static bool netif_is_virt_wifi_dev(const struct net_device *dev)
{
	return rcu_access_pointer(dev->rx_handler) == virt_wifi_rx_handler;
}

static int virt_wifi_event(struct notifier_block *this, unsigned long event,
			   void *ptr)
{
	struct net_device *lower_dev = netdev_notifier_info_to_dev(ptr);
	struct virt_wifi_netdev_priv *priv;
	struct net_device *upper_dev;
	LIST_HEAD(list_kill);

	if (!netif_is_virt_wifi_dev(lower_dev))
		return NOTIFY_DONE;

	switch (event) {
	case NETDEV_UNREGISTER:
		priv = rtnl_dereference(lower_dev->rx_handler_data);
		if (!priv)
			return NOTIFY_DONE;

		upper_dev = priv->upperdev;

		upper_dev->rtnl_link_ops->dellink(upper_dev, &list_kill);
		unregister_netdevice_many(&list_kill);
		break;
	}

	return NOTIFY_DONE;
}

static struct notifier_block virt_wifi_notifier = {
	.notifier_call = virt_wifi_event,
};

/* Acquires and releases the rtnl lock. */
static int __init virt_wifi_init_module(void)
{
	int err;

	/* Guaranteed to be locallly-administered and not multicast. */
	eth_random_addr(fake_router_bssid);

	err = register_netdevice_notifier(&virt_wifi_notifier);
	if (err)
		return err;

	err = -ENOMEM;
	common_wiphy = virt_wifi_make_wiphy();
	if (!common_wiphy)
		goto notifier;

	err = rtnl_link_register(&virt_wifi_link_ops);
	if (err)
		goto destroy_wiphy;

	return 0;

destroy_wiphy:
	virt_wifi_destroy_wiphy(common_wiphy);
notifier:
	unregister_netdevice_notifier(&virt_wifi_notifier);
	return err;
}

/* Acquires and releases the rtnl lock. */
static void __exit virt_wifi_cleanup_module(void)
{
	/* Will delete any devices that depend on the wiphy. */
	rtnl_link_unregister(&virt_wifi_link_ops);
	virt_wifi_destroy_wiphy(common_wiphy);
	unregister_netdevice_notifier(&virt_wifi_notifier);
}

module_init(virt_wifi_init_module);
module_exit(virt_wifi_cleanup_module);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Cody Schuffelen <schuffelen@google.com>");
MODULE_DESCRIPTION("Driver for a wireless wrapper of ethernet devices");
MODULE_ALIAS_RTNL_LINK("virt_wifi");