1/*
2 *	IEEE 802.1D Generic Attribute Registration Protocol (GARP)
3 *
4 *	Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
5 *
6 *	This program is free software; you can redistribute it and/or
7 *	modify it under the terms of the GNU General Public License
8 *	version 2 as published by the Free Software Foundation.
9 */
10#include <linux/kernel.h>
11#include <linux/timer.h>
12#include <linux/skbuff.h>
13#include <linux/netdevice.h>
14#include <linux/etherdevice.h>
15#include <linux/rtnetlink.h>
16#include <linux/llc.h>
17#include <linux/slab.h>
18#include <linux/module.h>
19#include <net/llc.h>
20#include <net/llc_pdu.h>
21#include <net/garp.h>
22#include <asm/unaligned.h>
23
24static unsigned int garp_join_time __read_mostly = 200;
25module_param(garp_join_time, uint, 0644);
26MODULE_PARM_DESC(garp_join_time, "Join time in ms (default 200ms)");
27MODULE_LICENSE("GPL");
28
29static const struct garp_state_trans {
30	u8	state;
31	u8	action;
32} garp_applicant_state_table[GARP_APPLICANT_MAX + 1][GARP_EVENT_MAX + 1] = {
33	[GARP_APPLICANT_VA] = {
34		[GARP_EVENT_TRANSMIT_PDU]	= { .state = GARP_APPLICANT_AA,
35						    .action = GARP_ACTION_S_JOIN_IN },
36		[GARP_EVENT_R_JOIN_IN]		= { .state = GARP_APPLICANT_AA },
37		[GARP_EVENT_R_JOIN_EMPTY]	= { .state = GARP_APPLICANT_VA },
38		[GARP_EVENT_R_EMPTY]		= { .state = GARP_APPLICANT_VA },
39		[GARP_EVENT_R_LEAVE_IN]		= { .state = GARP_APPLICANT_VA },
40		[GARP_EVENT_R_LEAVE_EMPTY]	= { .state = GARP_APPLICANT_VP },
41		[GARP_EVENT_REQ_JOIN]		= { .state = GARP_APPLICANT_INVALID },
42		[GARP_EVENT_REQ_LEAVE]		= { .state = GARP_APPLICANT_LA },
43	},
44	[GARP_APPLICANT_AA] = {
45		[GARP_EVENT_TRANSMIT_PDU]	= { .state = GARP_APPLICANT_QA,
46						    .action = GARP_ACTION_S_JOIN_IN },
47		[GARP_EVENT_R_JOIN_IN]		= { .state = GARP_APPLICANT_QA },
48		[GARP_EVENT_R_JOIN_EMPTY]	= { .state = GARP_APPLICANT_VA },
49		[GARP_EVENT_R_EMPTY]		= { .state = GARP_APPLICANT_VA },
50		[GARP_EVENT_R_LEAVE_IN]		= { .state = GARP_APPLICANT_VA },
51		[GARP_EVENT_R_LEAVE_EMPTY]	= { .state = GARP_APPLICANT_VP },
52		[GARP_EVENT_REQ_JOIN]		= { .state = GARP_APPLICANT_INVALID },
53		[GARP_EVENT_REQ_LEAVE]		= { .state = GARP_APPLICANT_LA },
54	},
55	[GARP_APPLICANT_QA] = {
56		[GARP_EVENT_TRANSMIT_PDU]	= { .state = GARP_APPLICANT_INVALID },
57		[GARP_EVENT_R_JOIN_IN]		= { .state = GARP_APPLICANT_QA },
58		[GARP_EVENT_R_JOIN_EMPTY]	= { .state = GARP_APPLICANT_VA },
59		[GARP_EVENT_R_EMPTY]		= { .state = GARP_APPLICANT_VA },
60		[GARP_EVENT_R_LEAVE_IN]		= { .state = GARP_APPLICANT_VP },
61		[GARP_EVENT_R_LEAVE_EMPTY]	= { .state = GARP_APPLICANT_VP },
62		[GARP_EVENT_REQ_JOIN]		= { .state = GARP_APPLICANT_INVALID },
63		[GARP_EVENT_REQ_LEAVE]		= { .state = GARP_APPLICANT_LA },
64	},
65	[GARP_APPLICANT_LA] = {
66		[GARP_EVENT_TRANSMIT_PDU]	= { .state = GARP_APPLICANT_VO,
67						    .action = GARP_ACTION_S_LEAVE_EMPTY },
68		[GARP_EVENT_R_JOIN_IN]		= { .state = GARP_APPLICANT_LA },
69		[GARP_EVENT_R_JOIN_EMPTY]	= { .state = GARP_APPLICANT_VO },
70		[GARP_EVENT_R_EMPTY]		= { .state = GARP_APPLICANT_LA },
71		[GARP_EVENT_R_LEAVE_IN]		= { .state = GARP_APPLICANT_LA },
72		[GARP_EVENT_R_LEAVE_EMPTY]	= { .state = GARP_APPLICANT_VO },
73		[GARP_EVENT_REQ_JOIN]		= { .state = GARP_APPLICANT_VA },
74		[GARP_EVENT_REQ_LEAVE]		= { .state = GARP_APPLICANT_INVALID },
75	},
76	[GARP_APPLICANT_VP] = {
77		[GARP_EVENT_TRANSMIT_PDU]	= { .state = GARP_APPLICANT_AA,
78						    .action = GARP_ACTION_S_JOIN_IN },
79		[GARP_EVENT_R_JOIN_IN]		= { .state = GARP_APPLICANT_AP },
80		[GARP_EVENT_R_JOIN_EMPTY]	= { .state = GARP_APPLICANT_VP },
81		[GARP_EVENT_R_EMPTY]		= { .state = GARP_APPLICANT_VP },
82		[GARP_EVENT_R_LEAVE_IN]		= { .state = GARP_APPLICANT_VP },
83		[GARP_EVENT_R_LEAVE_EMPTY]	= { .state = GARP_APPLICANT_VP },
84		[GARP_EVENT_REQ_JOIN]		= { .state = GARP_APPLICANT_INVALID },
85		[GARP_EVENT_REQ_LEAVE]		= { .state = GARP_APPLICANT_VO },
86	},
87	[GARP_APPLICANT_AP] = {
88		[GARP_EVENT_TRANSMIT_PDU]	= { .state = GARP_APPLICANT_QA,
89						    .action = GARP_ACTION_S_JOIN_IN },
90		[GARP_EVENT_R_JOIN_IN]		= { .state = GARP_APPLICANT_QP },
91		[GARP_EVENT_R_JOIN_EMPTY]	= { .state = GARP_APPLICANT_VP },
92		[GARP_EVENT_R_EMPTY]		= { .state = GARP_APPLICANT_VP },
93		[GARP_EVENT_R_LEAVE_IN]		= { .state = GARP_APPLICANT_VP },
94		[GARP_EVENT_R_LEAVE_EMPTY]	= { .state = GARP_APPLICANT_VP },
95		[GARP_EVENT_REQ_JOIN]		= { .state = GARP_APPLICANT_INVALID },
96		[GARP_EVENT_REQ_LEAVE]		= { .state = GARP_APPLICANT_AO },
97	},
98	[GARP_APPLICANT_QP] = {
99		[GARP_EVENT_TRANSMIT_PDU]	= { .state = GARP_APPLICANT_INVALID },
100		[GARP_EVENT_R_JOIN_IN]		= { .state = GARP_APPLICANT_QP },
101		[GARP_EVENT_R_JOIN_EMPTY]	= { .state = GARP_APPLICANT_VP },
102		[GARP_EVENT_R_EMPTY]		= { .state = GARP_APPLICANT_VP },
103		[GARP_EVENT_R_LEAVE_IN]		= { .state = GARP_APPLICANT_VP },
104		[GARP_EVENT_R_LEAVE_EMPTY]	= { .state = GARP_APPLICANT_VP },
105		[GARP_EVENT_REQ_JOIN]		= { .state = GARP_APPLICANT_INVALID },
106		[GARP_EVENT_REQ_LEAVE]		= { .state = GARP_APPLICANT_QO },
107	},
108	[GARP_APPLICANT_VO] = {
109		[GARP_EVENT_TRANSMIT_PDU]	= { .state = GARP_APPLICANT_INVALID },
110		[GARP_EVENT_R_JOIN_IN]		= { .state = GARP_APPLICANT_AO },
111		[GARP_EVENT_R_JOIN_EMPTY]	= { .state = GARP_APPLICANT_VO },
112		[GARP_EVENT_R_EMPTY]		= { .state = GARP_APPLICANT_VO },
113		[GARP_EVENT_R_LEAVE_IN]		= { .state = GARP_APPLICANT_VO },
114		[GARP_EVENT_R_LEAVE_EMPTY]	= { .state = GARP_APPLICANT_VO },
115		[GARP_EVENT_REQ_JOIN]		= { .state = GARP_APPLICANT_VP },
116		[GARP_EVENT_REQ_LEAVE]		= { .state = GARP_APPLICANT_INVALID },
117	},
118	[GARP_APPLICANT_AO] = {
119		[GARP_EVENT_TRANSMIT_PDU]	= { .state = GARP_APPLICANT_INVALID },
120		[GARP_EVENT_R_JOIN_IN]		= { .state = GARP_APPLICANT_QO },
121		[GARP_EVENT_R_JOIN_EMPTY]	= { .state = GARP_APPLICANT_VO },
122		[GARP_EVENT_R_EMPTY]		= { .state = GARP_APPLICANT_VO },
123		[GARP_EVENT_R_LEAVE_IN]		= { .state = GARP_APPLICANT_VO },
124		[GARP_EVENT_R_LEAVE_EMPTY]	= { .state = GARP_APPLICANT_VO },
125		[GARP_EVENT_REQ_JOIN]		= { .state = GARP_APPLICANT_AP },
126		[GARP_EVENT_REQ_LEAVE]		= { .state = GARP_APPLICANT_INVALID },
127	},
128	[GARP_APPLICANT_QO] = {
129		[GARP_EVENT_TRANSMIT_PDU]	= { .state = GARP_APPLICANT_INVALID },
130		[GARP_EVENT_R_JOIN_IN]		= { .state = GARP_APPLICANT_QO },
131		[GARP_EVENT_R_JOIN_EMPTY]	= { .state = GARP_APPLICANT_VO },
132		[GARP_EVENT_R_EMPTY]		= { .state = GARP_APPLICANT_VO },
133		[GARP_EVENT_R_LEAVE_IN]		= { .state = GARP_APPLICANT_VO },
134		[GARP_EVENT_R_LEAVE_EMPTY]	= { .state = GARP_APPLICANT_VO },
135		[GARP_EVENT_REQ_JOIN]		= { .state = GARP_APPLICANT_QP },
136		[GARP_EVENT_REQ_LEAVE]		= { .state = GARP_APPLICANT_INVALID },
137	},
138};
139
140static int garp_attr_cmp(const struct garp_attr *attr,
141			 const void *data, u8 len, u8 type)
142{
143	if (attr->type != type)
144		return attr->type - type;
145	if (attr->dlen != len)
146		return attr->dlen - len;
147	return memcmp(attr->data, data, len);
148}
149
150static struct garp_attr *garp_attr_lookup(const struct garp_applicant *app,
151					  const void *data, u8 len, u8 type)
152{
153	struct rb_node *parent = app->gid.rb_node;
154	struct garp_attr *attr;
155	int d;
156
157	while (parent) {
158		attr = rb_entry(parent, struct garp_attr, node);
159		d = garp_attr_cmp(attr, data, len, type);
160		if (d > 0)
161			parent = parent->rb_left;
162		else if (d < 0)
163			parent = parent->rb_right;
164		else
165			return attr;
166	}
167	return NULL;
168}
169
170static struct garp_attr *garp_attr_create(struct garp_applicant *app,
171					  const void *data, u8 len, u8 type)
172{
173	struct rb_node *parent = NULL, **p = &app->gid.rb_node;
174	struct garp_attr *attr;
175	int d;
176
177	while (*p) {
178		parent = *p;
179		attr = rb_entry(parent, struct garp_attr, node);
180		d = garp_attr_cmp(attr, data, len, type);
181		if (d > 0)
182			p = &parent->rb_left;
183		else if (d < 0)
184			p = &parent->rb_right;
185		else {
186			/* The attribute already exists; re-use it. */
187			return attr;
188		}
189	}
190	attr = kmalloc(sizeof(*attr) + len, GFP_ATOMIC);
191	if (!attr)
192		return attr;
193	attr->state = GARP_APPLICANT_VO;
194	attr->type  = type;
195	attr->dlen  = len;
196	memcpy(attr->data, data, len);
197
198	rb_link_node(&attr->node, parent, p);
199	rb_insert_color(&attr->node, &app->gid);
200	return attr;
201}
202
203static void garp_attr_destroy(struct garp_applicant *app, struct garp_attr *attr)
204{
205	rb_erase(&attr->node, &app->gid);
206	kfree(attr);
207}
208
209static int garp_pdu_init(struct garp_applicant *app)
210{
211	struct sk_buff *skb;
212	struct garp_pdu_hdr *gp;
213
214#define LLC_RESERVE	sizeof(struct llc_pdu_un)
215	skb = alloc_skb(app->dev->mtu + LL_RESERVED_SPACE(app->dev),
216			GFP_ATOMIC);
217	if (!skb)
218		return -ENOMEM;
219
220	skb->dev = app->dev;
221	skb->protocol = htons(ETH_P_802_2);
222	skb_reserve(skb, LL_RESERVED_SPACE(app->dev) + LLC_RESERVE);
223
224	gp = (struct garp_pdu_hdr *)__skb_put(skb, sizeof(*gp));
225	put_unaligned(htons(GARP_PROTOCOL_ID), &gp->protocol);
226
227	app->pdu = skb;
228	return 0;
229}
230
231static int garp_pdu_append_end_mark(struct garp_applicant *app)
232{
233	if (skb_tailroom(app->pdu) < sizeof(u8))
234		return -1;
235	*(u8 *)__skb_put(app->pdu, sizeof(u8)) = GARP_END_MARK;
236	return 0;
237}
238
239static void garp_pdu_queue(struct garp_applicant *app)
240{
241	if (!app->pdu)
242		return;
243
244	garp_pdu_append_end_mark(app);
245	garp_pdu_append_end_mark(app);
246
247	llc_pdu_header_init(app->pdu, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
248			    LLC_SAP_BSPAN, LLC_PDU_CMD);
249	llc_pdu_init_as_ui_cmd(app->pdu);
250	llc_mac_hdr_init(app->pdu, app->dev->dev_addr,
251			 app->app->proto.group_address);
252
253	skb_queue_tail(&app->queue, app->pdu);
254	app->pdu = NULL;
255}
256
257static void garp_queue_xmit(struct garp_applicant *app)
258{
259	struct sk_buff *skb;
260
261	while ((skb = skb_dequeue(&app->queue)))
262		dev_queue_xmit(skb);
263}
264
265static int garp_pdu_append_msg(struct garp_applicant *app, u8 attrtype)
266{
267	struct garp_msg_hdr *gm;
268
269	if (skb_tailroom(app->pdu) < sizeof(*gm))
270		return -1;
271	gm = (struct garp_msg_hdr *)__skb_put(app->pdu, sizeof(*gm));
272	gm->attrtype = attrtype;
273	garp_cb(app->pdu)->cur_type = attrtype;
274	return 0;
275}
276
277static int garp_pdu_append_attr(struct garp_applicant *app,
278				const struct garp_attr *attr,
279				enum garp_attr_event event)
280{
281	struct garp_attr_hdr *ga;
282	unsigned int len;
283	int err;
284again:
285	if (!app->pdu) {
286		err = garp_pdu_init(app);
287		if (err < 0)
288			return err;
289	}
290
291	if (garp_cb(app->pdu)->cur_type != attr->type) {
292		if (garp_cb(app->pdu)->cur_type &&
293		    garp_pdu_append_end_mark(app) < 0)
294			goto queue;
295		if (garp_pdu_append_msg(app, attr->type) < 0)
296			goto queue;
297	}
298
299	len = sizeof(*ga) + attr->dlen;
300	if (skb_tailroom(app->pdu) < len)
301		goto queue;
302	ga = (struct garp_attr_hdr *)__skb_put(app->pdu, len);
303	ga->len   = len;
304	ga->event = event;
305	memcpy(ga->data, attr->data, attr->dlen);
306	return 0;
307
308queue:
309	garp_pdu_queue(app);
310	goto again;
311}
312
313static void garp_attr_event(struct garp_applicant *app,
314			    struct garp_attr *attr, enum garp_event event)
315{
316	enum garp_applicant_state state;
317
318	state = garp_applicant_state_table[attr->state][event].state;
319	if (state == GARP_APPLICANT_INVALID)
320		return;
321
322	switch (garp_applicant_state_table[attr->state][event].action) {
323	case GARP_ACTION_NONE:
324		break;
325	case GARP_ACTION_S_JOIN_IN:
326		/* When appending the attribute fails, don't update state in
327		 * order to retry on next TRANSMIT_PDU event. */
328		if (garp_pdu_append_attr(app, attr, GARP_JOIN_IN) < 0)
329			return;
330		break;
331	case GARP_ACTION_S_LEAVE_EMPTY:
332		garp_pdu_append_attr(app, attr, GARP_LEAVE_EMPTY);
333		/* As a pure applicant, sending a leave message implies that
334		 * the attribute was unregistered and can be destroyed. */
335		garp_attr_destroy(app, attr);
336		return;
337	default:
338		WARN_ON(1);
339	}
340
341	attr->state = state;
342}
343
344int garp_request_join(const struct net_device *dev,
345		      const struct garp_application *appl,
346		      const void *data, u8 len, u8 type)
347{
348	struct garp_port *port = rtnl_dereference(dev->garp_port);
349	struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);
350	struct garp_attr *attr;
351
352	spin_lock_bh(&app->lock);
353	attr = garp_attr_create(app, data, len, type);
354	if (!attr) {
355		spin_unlock_bh(&app->lock);
356		return -ENOMEM;
357	}
358	garp_attr_event(app, attr, GARP_EVENT_REQ_JOIN);
359	spin_unlock_bh(&app->lock);
360	return 0;
361}
362EXPORT_SYMBOL_GPL(garp_request_join);
363
364void garp_request_leave(const struct net_device *dev,
365			const struct garp_application *appl,
366			const void *data, u8 len, u8 type)
367{
368	struct garp_port *port = rtnl_dereference(dev->garp_port);
369	struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);
370	struct garp_attr *attr;
371
372	spin_lock_bh(&app->lock);
373	attr = garp_attr_lookup(app, data, len, type);
374	if (!attr) {
375		spin_unlock_bh(&app->lock);
376		return;
377	}
378	garp_attr_event(app, attr, GARP_EVENT_REQ_LEAVE);
379	spin_unlock_bh(&app->lock);
380}
381EXPORT_SYMBOL_GPL(garp_request_leave);
382
383static void garp_gid_event(struct garp_applicant *app, enum garp_event event)
384{
385	struct rb_node *node, *next;
386	struct garp_attr *attr;
387
388	for (node = rb_first(&app->gid);
389	     next = node ? rb_next(node) : NULL, node != NULL;
390	     node = next) {
391		attr = rb_entry(node, struct garp_attr, node);
392		garp_attr_event(app, attr, event);
393	}
394}
395
396static void garp_join_timer_arm(struct garp_applicant *app)
397{
398	unsigned long delay;
399
400	delay = (u64)msecs_to_jiffies(garp_join_time) * prandom_u32() >> 32;
401	mod_timer(&app->join_timer, jiffies + delay);
402}
403
404static void garp_join_timer(unsigned long data)
405{
406	struct garp_applicant *app = (struct garp_applicant *)data;
407
408	spin_lock(&app->lock);
409	garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
410	garp_pdu_queue(app);
411	spin_unlock(&app->lock);
412
413	garp_queue_xmit(app);
414	garp_join_timer_arm(app);
415}
416
417static int garp_pdu_parse_end_mark(struct sk_buff *skb)
418{
419	if (!pskb_may_pull(skb, sizeof(u8)))
420		return -1;
421	if (*skb->data == GARP_END_MARK) {
422		skb_pull(skb, sizeof(u8));
423		return -1;
424	}
425	return 0;
426}
427
428static int garp_pdu_parse_attr(struct garp_applicant *app, struct sk_buff *skb,
429			       u8 attrtype)
430{
431	const struct garp_attr_hdr *ga;
432	struct garp_attr *attr;
433	enum garp_event event;
434	unsigned int dlen;
435
436	if (!pskb_may_pull(skb, sizeof(*ga)))
437		return -1;
438	ga = (struct garp_attr_hdr *)skb->data;
439	if (ga->len < sizeof(*ga))
440		return -1;
441
442	if (!pskb_may_pull(skb, ga->len))
443		return -1;
444	skb_pull(skb, ga->len);
445	dlen = sizeof(*ga) - ga->len;
446
447	if (attrtype > app->app->maxattr)
448		return 0;
449
450	switch (ga->event) {
451	case GARP_LEAVE_ALL:
452		if (dlen != 0)
453			return -1;
454		garp_gid_event(app, GARP_EVENT_R_LEAVE_EMPTY);
455		return 0;
456	case GARP_JOIN_EMPTY:
457		event = GARP_EVENT_R_JOIN_EMPTY;
458		break;
459	case GARP_JOIN_IN:
460		event = GARP_EVENT_R_JOIN_IN;
461		break;
462	case GARP_LEAVE_EMPTY:
463		event = GARP_EVENT_R_LEAVE_EMPTY;
464		break;
465	case GARP_EMPTY:
466		event = GARP_EVENT_R_EMPTY;
467		break;
468	default:
469		return 0;
470	}
471
472	if (dlen == 0)
473		return -1;
474	attr = garp_attr_lookup(app, ga->data, dlen, attrtype);
475	if (attr == NULL)
476		return 0;
477	garp_attr_event(app, attr, event);
478	return 0;
479}
480
481static int garp_pdu_parse_msg(struct garp_applicant *app, struct sk_buff *skb)
482{
483	const struct garp_msg_hdr *gm;
484
485	if (!pskb_may_pull(skb, sizeof(*gm)))
486		return -1;
487	gm = (struct garp_msg_hdr *)skb->data;
488	if (gm->attrtype == 0)
489		return -1;
490	skb_pull(skb, sizeof(*gm));
491
492	while (skb->len > 0) {
493		if (garp_pdu_parse_attr(app, skb, gm->attrtype) < 0)
494			return -1;
495		if (garp_pdu_parse_end_mark(skb) < 0)
496			break;
497	}
498	return 0;
499}
500
501static void garp_pdu_rcv(const struct stp_proto *proto, struct sk_buff *skb,
502			 struct net_device *dev)
503{
504	struct garp_application *appl = proto->data;
505	struct garp_port *port;
506	struct garp_applicant *app;
507	const struct garp_pdu_hdr *gp;
508
509	port = rcu_dereference(dev->garp_port);
510	if (!port)
511		goto err;
512	app = rcu_dereference(port->applicants[appl->type]);
513	if (!app)
514		goto err;
515
516	if (!pskb_may_pull(skb, sizeof(*gp)))
517		goto err;
518	gp = (struct garp_pdu_hdr *)skb->data;
519	if (get_unaligned(&gp->protocol) != htons(GARP_PROTOCOL_ID))
520		goto err;
521	skb_pull(skb, sizeof(*gp));
522
523	spin_lock(&app->lock);
524	while (skb->len > 0) {
525		if (garp_pdu_parse_msg(app, skb) < 0)
526			break;
527		if (garp_pdu_parse_end_mark(skb) < 0)
528			break;
529	}
530	spin_unlock(&app->lock);
531err:
532	kfree_skb(skb);
533}
534
535static int garp_init_port(struct net_device *dev)
536{
537	struct garp_port *port;
538
539	port = kzalloc(sizeof(*port), GFP_KERNEL);
540	if (!port)
541		return -ENOMEM;
542	rcu_assign_pointer(dev->garp_port, port);
543	return 0;
544}
545
546static void garp_release_port(struct net_device *dev)
547{
548	struct garp_port *port = rtnl_dereference(dev->garp_port);
549	unsigned int i;
550
551	for (i = 0; i <= GARP_APPLICATION_MAX; i++) {
552		if (rtnl_dereference(port->applicants[i]))
553			return;
554	}
555	RCU_INIT_POINTER(dev->garp_port, NULL);
556	kfree_rcu(port, rcu);
557}
558
559int garp_init_applicant(struct net_device *dev, struct garp_application *appl)
560{
561	struct garp_applicant *app;
562	int err;
563
564	ASSERT_RTNL();
565
566	if (!rtnl_dereference(dev->garp_port)) {
567		err = garp_init_port(dev);
568		if (err < 0)
569			goto err1;
570	}
571
572	err = -ENOMEM;
573	app = kzalloc(sizeof(*app), GFP_KERNEL);
574	if (!app)
575		goto err2;
576
577	err = dev_mc_add(dev, appl->proto.group_address);
578	if (err < 0)
579		goto err3;
580
581	app->dev = dev;
582	app->app = appl;
583	app->gid = RB_ROOT;
584	spin_lock_init(&app->lock);
585	skb_queue_head_init(&app->queue);
586	rcu_assign_pointer(dev->garp_port->applicants[appl->type], app);
587	setup_timer(&app->join_timer, garp_join_timer, (unsigned long)app);
588	garp_join_timer_arm(app);
589	return 0;
590
591err3:
592	kfree(app);
593err2:
594	garp_release_port(dev);
595err1:
596	return err;
597}
598EXPORT_SYMBOL_GPL(garp_init_applicant);
599
600void garp_uninit_applicant(struct net_device *dev, struct garp_application *appl)
601{
602	struct garp_port *port = rtnl_dereference(dev->garp_port);
603	struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);
604
605	ASSERT_RTNL();
606
607	RCU_INIT_POINTER(port->applicants[appl->type], NULL);
608
609	/* Delete timer and generate a final TRANSMIT_PDU event to flush out
610	 * all pending messages before the applicant is gone. */
611	del_timer_sync(&app->join_timer);
612
613	spin_lock_bh(&app->lock);
614	garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
615	garp_pdu_queue(app);
616	spin_unlock_bh(&app->lock);
617
618	garp_queue_xmit(app);
619
620	dev_mc_del(dev, appl->proto.group_address);
621	kfree_rcu(app, rcu);
622	garp_release_port(dev);
623}
624EXPORT_SYMBOL_GPL(garp_uninit_applicant);
625
626int garp_register_application(struct garp_application *appl)
627{
628	appl->proto.rcv = garp_pdu_rcv;
629	appl->proto.data = appl;
630	return stp_proto_register(&appl->proto);
631}
632EXPORT_SYMBOL_GPL(garp_register_application);
633
634void garp_unregister_application(struct garp_application *appl)
635{
636	stp_proto_unregister(&appl->proto);
637}
638EXPORT_SYMBOL_GPL(garp_unregister_application);
639