netfilter: nft_set_rbtree: skip elements in transaction from garbage collection
[platform/kernel/linux-rpi.git] / net / 802 / garp.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *      IEEE 802.1D Generic Attribute Registration Protocol (GARP)
4  *
5  *      Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
6  */
7 #include <linux/kernel.h>
8 #include <linux/timer.h>
9 #include <linux/skbuff.h>
10 #include <linux/netdevice.h>
11 #include <linux/etherdevice.h>
12 #include <linux/rtnetlink.h>
13 #include <linux/llc.h>
14 #include <linux/slab.h>
15 #include <linux/module.h>
16 #include <net/llc.h>
17 #include <net/llc_pdu.h>
18 #include <net/garp.h>
19 #include <asm/unaligned.h>
20
21 static unsigned int garp_join_time __read_mostly = 200;
22 module_param(garp_join_time, uint, 0644);
23 MODULE_PARM_DESC(garp_join_time, "Join time in ms (default 200ms)");
24 MODULE_LICENSE("GPL");
25
26 static const struct garp_state_trans {
27         u8      state;
28         u8      action;
29 } garp_applicant_state_table[GARP_APPLICANT_MAX + 1][GARP_EVENT_MAX + 1] = {
30         [GARP_APPLICANT_VA] = {
31                 [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_AA,
32                                                     .action = GARP_ACTION_S_JOIN_IN },
33                 [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_AA },
34                 [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VA },
35                 [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VA },
36                 [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VA },
37                 [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
38                 [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
39                 [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_LA },
40         },
41         [GARP_APPLICANT_AA] = {
42                 [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_QA,
43                                                     .action = GARP_ACTION_S_JOIN_IN },
44                 [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QA },
45                 [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VA },
46                 [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VA },
47                 [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VA },
48                 [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
49                 [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
50                 [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_LA },
51         },
52         [GARP_APPLICANT_QA] = {
53                 [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
54                 [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QA },
55                 [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VA },
56                 [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VA },
57                 [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VP },
58                 [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
59                 [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
60                 [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_LA },
61         },
62         [GARP_APPLICANT_LA] = {
63                 [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_VO,
64                                                     .action = GARP_ACTION_S_LEAVE_EMPTY },
65                 [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_LA },
66                 [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VO },
67                 [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_LA },
68                 [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_LA },
69                 [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VO },
70                 [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_VA },
71                 [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_INVALID },
72         },
73         [GARP_APPLICANT_VP] = {
74                 [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_AA,
75                                                     .action = GARP_ACTION_S_JOIN_IN },
76                 [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_AP },
77                 [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VP },
78                 [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VP },
79                 [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VP },
80                 [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
81                 [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
82                 [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_VO },
83         },
84         [GARP_APPLICANT_AP] = {
85                 [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_QA,
86                                                     .action = GARP_ACTION_S_JOIN_IN },
87                 [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QP },
88                 [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VP },
89                 [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VP },
90                 [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VP },
91                 [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
92                 [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
93                 [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_AO },
94         },
95         [GARP_APPLICANT_QP] = {
96                 [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
97                 [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QP },
98                 [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VP },
99                 [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VP },
100                 [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VP },
101                 [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
102                 [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
103                 [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_QO },
104         },
105         [GARP_APPLICANT_VO] = {
106                 [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
107                 [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_AO },
108                 [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VO },
109                 [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VO },
110                 [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VO },
111                 [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VO },
112                 [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_VP },
113                 [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_INVALID },
114         },
115         [GARP_APPLICANT_AO] = {
116                 [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
117                 [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QO },
118                 [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VO },
119                 [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VO },
120                 [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VO },
121                 [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VO },
122                 [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_AP },
123                 [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_INVALID },
124         },
125         [GARP_APPLICANT_QO] = {
126                 [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
127                 [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QO },
128                 [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VO },
129                 [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VO },
130                 [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VO },
131                 [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VO },
132                 [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_QP },
133                 [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_INVALID },
134         },
135 };
136
137 static int garp_attr_cmp(const struct garp_attr *attr,
138                          const void *data, u8 len, u8 type)
139 {
140         if (attr->type != type)
141                 return attr->type - type;
142         if (attr->dlen != len)
143                 return attr->dlen - len;
144         return memcmp(attr->data, data, len);
145 }
146
147 static struct garp_attr *garp_attr_lookup(const struct garp_applicant *app,
148                                           const void *data, u8 len, u8 type)
149 {
150         struct rb_node *parent = app->gid.rb_node;
151         struct garp_attr *attr;
152         int d;
153
154         while (parent) {
155                 attr = rb_entry(parent, struct garp_attr, node);
156                 d = garp_attr_cmp(attr, data, len, type);
157                 if (d > 0)
158                         parent = parent->rb_left;
159                 else if (d < 0)
160                         parent = parent->rb_right;
161                 else
162                         return attr;
163         }
164         return NULL;
165 }
166
167 static struct garp_attr *garp_attr_create(struct garp_applicant *app,
168                                           const void *data, u8 len, u8 type)
169 {
170         struct rb_node *parent = NULL, **p = &app->gid.rb_node;
171         struct garp_attr *attr;
172         int d;
173
174         while (*p) {
175                 parent = *p;
176                 attr = rb_entry(parent, struct garp_attr, node);
177                 d = garp_attr_cmp(attr, data, len, type);
178                 if (d > 0)
179                         p = &parent->rb_left;
180                 else if (d < 0)
181                         p = &parent->rb_right;
182                 else {
183                         /* The attribute already exists; re-use it. */
184                         return attr;
185                 }
186         }
187         attr = kmalloc(sizeof(*attr) + len, GFP_ATOMIC);
188         if (!attr)
189                 return attr;
190         attr->state = GARP_APPLICANT_VO;
191         attr->type  = type;
192         attr->dlen  = len;
193         memcpy(attr->data, data, len);
194
195         rb_link_node(&attr->node, parent, p);
196         rb_insert_color(&attr->node, &app->gid);
197         return attr;
198 }
199
200 static void garp_attr_destroy(struct garp_applicant *app, struct garp_attr *attr)
201 {
202         rb_erase(&attr->node, &app->gid);
203         kfree(attr);
204 }
205
206 static void garp_attr_destroy_all(struct garp_applicant *app)
207 {
208         struct rb_node *node, *next;
209         struct garp_attr *attr;
210
211         for (node = rb_first(&app->gid);
212              next = node ? rb_next(node) : NULL, node != NULL;
213              node = next) {
214                 attr = rb_entry(node, struct garp_attr, node);
215                 garp_attr_destroy(app, attr);
216         }
217 }
218
219 static int garp_pdu_init(struct garp_applicant *app)
220 {
221         struct sk_buff *skb;
222         struct garp_pdu_hdr *gp;
223
224 #define LLC_RESERVE     sizeof(struct llc_pdu_un)
225         skb = alloc_skb(app->dev->mtu + LL_RESERVED_SPACE(app->dev),
226                         GFP_ATOMIC);
227         if (!skb)
228                 return -ENOMEM;
229
230         skb->dev = app->dev;
231         skb->protocol = htons(ETH_P_802_2);
232         skb_reserve(skb, LL_RESERVED_SPACE(app->dev) + LLC_RESERVE);
233
234         gp = __skb_put(skb, sizeof(*gp));
235         put_unaligned(htons(GARP_PROTOCOL_ID), &gp->protocol);
236
237         app->pdu = skb;
238         return 0;
239 }
240
241 static int garp_pdu_append_end_mark(struct garp_applicant *app)
242 {
243         if (skb_tailroom(app->pdu) < sizeof(u8))
244                 return -1;
245         __skb_put_u8(app->pdu, GARP_END_MARK);
246         return 0;
247 }
248
249 static void garp_pdu_queue(struct garp_applicant *app)
250 {
251         if (!app->pdu)
252                 return;
253
254         garp_pdu_append_end_mark(app);
255         garp_pdu_append_end_mark(app);
256
257         llc_pdu_header_init(app->pdu, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
258                             LLC_SAP_BSPAN, LLC_PDU_CMD);
259         llc_pdu_init_as_ui_cmd(app->pdu);
260         llc_mac_hdr_init(app->pdu, app->dev->dev_addr,
261                          app->app->proto.group_address);
262
263         skb_queue_tail(&app->queue, app->pdu);
264         app->pdu = NULL;
265 }
266
267 static void garp_queue_xmit(struct garp_applicant *app)
268 {
269         struct sk_buff *skb;
270
271         while ((skb = skb_dequeue(&app->queue)))
272                 dev_queue_xmit(skb);
273 }
274
275 static int garp_pdu_append_msg(struct garp_applicant *app, u8 attrtype)
276 {
277         struct garp_msg_hdr *gm;
278
279         if (skb_tailroom(app->pdu) < sizeof(*gm))
280                 return -1;
281         gm = __skb_put(app->pdu, sizeof(*gm));
282         gm->attrtype = attrtype;
283         garp_cb(app->pdu)->cur_type = attrtype;
284         return 0;
285 }
286
287 static int garp_pdu_append_attr(struct garp_applicant *app,
288                                 const struct garp_attr *attr,
289                                 enum garp_attr_event event)
290 {
291         struct garp_attr_hdr *ga;
292         unsigned int len;
293         int err;
294 again:
295         if (!app->pdu) {
296                 err = garp_pdu_init(app);
297                 if (err < 0)
298                         return err;
299         }
300
301         if (garp_cb(app->pdu)->cur_type != attr->type) {
302                 if (garp_cb(app->pdu)->cur_type &&
303                     garp_pdu_append_end_mark(app) < 0)
304                         goto queue;
305                 if (garp_pdu_append_msg(app, attr->type) < 0)
306                         goto queue;
307         }
308
309         len = sizeof(*ga) + attr->dlen;
310         if (skb_tailroom(app->pdu) < len)
311                 goto queue;
312         ga = __skb_put(app->pdu, len);
313         ga->len   = len;
314         ga->event = event;
315         memcpy(ga->data, attr->data, attr->dlen);
316         return 0;
317
318 queue:
319         garp_pdu_queue(app);
320         goto again;
321 }
322
323 static void garp_attr_event(struct garp_applicant *app,
324                             struct garp_attr *attr, enum garp_event event)
325 {
326         enum garp_applicant_state state;
327
328         state = garp_applicant_state_table[attr->state][event].state;
329         if (state == GARP_APPLICANT_INVALID)
330                 return;
331
332         switch (garp_applicant_state_table[attr->state][event].action) {
333         case GARP_ACTION_NONE:
334                 break;
335         case GARP_ACTION_S_JOIN_IN:
336                 /* When appending the attribute fails, don't update state in
337                  * order to retry on next TRANSMIT_PDU event. */
338                 if (garp_pdu_append_attr(app, attr, GARP_JOIN_IN) < 0)
339                         return;
340                 break;
341         case GARP_ACTION_S_LEAVE_EMPTY:
342                 garp_pdu_append_attr(app, attr, GARP_LEAVE_EMPTY);
343                 /* As a pure applicant, sending a leave message implies that
344                  * the attribute was unregistered and can be destroyed. */
345                 garp_attr_destroy(app, attr);
346                 return;
347         default:
348                 WARN_ON(1);
349         }
350
351         attr->state = state;
352 }
353
354 int garp_request_join(const struct net_device *dev,
355                       const struct garp_application *appl,
356                       const void *data, u8 len, u8 type)
357 {
358         struct garp_port *port = rtnl_dereference(dev->garp_port);
359         struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);
360         struct garp_attr *attr;
361
362         spin_lock_bh(&app->lock);
363         attr = garp_attr_create(app, data, len, type);
364         if (!attr) {
365                 spin_unlock_bh(&app->lock);
366                 return -ENOMEM;
367         }
368         garp_attr_event(app, attr, GARP_EVENT_REQ_JOIN);
369         spin_unlock_bh(&app->lock);
370         return 0;
371 }
372 EXPORT_SYMBOL_GPL(garp_request_join);
373
374 void garp_request_leave(const struct net_device *dev,
375                         const struct garp_application *appl,
376                         const void *data, u8 len, u8 type)
377 {
378         struct garp_port *port = rtnl_dereference(dev->garp_port);
379         struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);
380         struct garp_attr *attr;
381
382         spin_lock_bh(&app->lock);
383         attr = garp_attr_lookup(app, data, len, type);
384         if (!attr) {
385                 spin_unlock_bh(&app->lock);
386                 return;
387         }
388         garp_attr_event(app, attr, GARP_EVENT_REQ_LEAVE);
389         spin_unlock_bh(&app->lock);
390 }
391 EXPORT_SYMBOL_GPL(garp_request_leave);
392
393 static void garp_gid_event(struct garp_applicant *app, enum garp_event event)
394 {
395         struct rb_node *node, *next;
396         struct garp_attr *attr;
397
398         for (node = rb_first(&app->gid);
399              next = node ? rb_next(node) : NULL, node != NULL;
400              node = next) {
401                 attr = rb_entry(node, struct garp_attr, node);
402                 garp_attr_event(app, attr, event);
403         }
404 }
405
406 static void garp_join_timer_arm(struct garp_applicant *app)
407 {
408         unsigned long delay;
409
410         delay = (u64)msecs_to_jiffies(garp_join_time) * prandom_u32() >> 32;
411         mod_timer(&app->join_timer, jiffies + delay);
412 }
413
414 static void garp_join_timer(struct timer_list *t)
415 {
416         struct garp_applicant *app = from_timer(app, t, join_timer);
417
418         spin_lock(&app->lock);
419         garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
420         garp_pdu_queue(app);
421         spin_unlock(&app->lock);
422
423         garp_queue_xmit(app);
424         garp_join_timer_arm(app);
425 }
426
427 static int garp_pdu_parse_end_mark(struct sk_buff *skb)
428 {
429         if (!pskb_may_pull(skb, sizeof(u8)))
430                 return -1;
431         if (*skb->data == GARP_END_MARK) {
432                 skb_pull(skb, sizeof(u8));
433                 return -1;
434         }
435         return 0;
436 }
437
438 static int garp_pdu_parse_attr(struct garp_applicant *app, struct sk_buff *skb,
439                                u8 attrtype)
440 {
441         const struct garp_attr_hdr *ga;
442         struct garp_attr *attr;
443         enum garp_event event;
444         unsigned int dlen;
445
446         if (!pskb_may_pull(skb, sizeof(*ga)))
447                 return -1;
448         ga = (struct garp_attr_hdr *)skb->data;
449         if (ga->len < sizeof(*ga))
450                 return -1;
451
452         if (!pskb_may_pull(skb, ga->len))
453                 return -1;
454         skb_pull(skb, ga->len);
455         dlen = sizeof(*ga) - ga->len;
456
457         if (attrtype > app->app->maxattr)
458                 return 0;
459
460         switch (ga->event) {
461         case GARP_LEAVE_ALL:
462                 if (dlen != 0)
463                         return -1;
464                 garp_gid_event(app, GARP_EVENT_R_LEAVE_EMPTY);
465                 return 0;
466         case GARP_JOIN_EMPTY:
467                 event = GARP_EVENT_R_JOIN_EMPTY;
468                 break;
469         case GARP_JOIN_IN:
470                 event = GARP_EVENT_R_JOIN_IN;
471                 break;
472         case GARP_LEAVE_EMPTY:
473                 event = GARP_EVENT_R_LEAVE_EMPTY;
474                 break;
475         case GARP_EMPTY:
476                 event = GARP_EVENT_R_EMPTY;
477                 break;
478         default:
479                 return 0;
480         }
481
482         if (dlen == 0)
483                 return -1;
484         attr = garp_attr_lookup(app, ga->data, dlen, attrtype);
485         if (attr == NULL)
486                 return 0;
487         garp_attr_event(app, attr, event);
488         return 0;
489 }
490
491 static int garp_pdu_parse_msg(struct garp_applicant *app, struct sk_buff *skb)
492 {
493         const struct garp_msg_hdr *gm;
494
495         if (!pskb_may_pull(skb, sizeof(*gm)))
496                 return -1;
497         gm = (struct garp_msg_hdr *)skb->data;
498         if (gm->attrtype == 0)
499                 return -1;
500         skb_pull(skb, sizeof(*gm));
501
502         while (skb->len > 0) {
503                 if (garp_pdu_parse_attr(app, skb, gm->attrtype) < 0)
504                         return -1;
505                 if (garp_pdu_parse_end_mark(skb) < 0)
506                         break;
507         }
508         return 0;
509 }
510
511 static void garp_pdu_rcv(const struct stp_proto *proto, struct sk_buff *skb,
512                          struct net_device *dev)
513 {
514         struct garp_application *appl = proto->data;
515         struct garp_port *port;
516         struct garp_applicant *app;
517         const struct garp_pdu_hdr *gp;
518
519         port = rcu_dereference(dev->garp_port);
520         if (!port)
521                 goto err;
522         app = rcu_dereference(port->applicants[appl->type]);
523         if (!app)
524                 goto err;
525
526         if (!pskb_may_pull(skb, sizeof(*gp)))
527                 goto err;
528         gp = (struct garp_pdu_hdr *)skb->data;
529         if (get_unaligned(&gp->protocol) != htons(GARP_PROTOCOL_ID))
530                 goto err;
531         skb_pull(skb, sizeof(*gp));
532
533         spin_lock(&app->lock);
534         while (skb->len > 0) {
535                 if (garp_pdu_parse_msg(app, skb) < 0)
536                         break;
537                 if (garp_pdu_parse_end_mark(skb) < 0)
538                         break;
539         }
540         spin_unlock(&app->lock);
541 err:
542         kfree_skb(skb);
543 }
544
545 static int garp_init_port(struct net_device *dev)
546 {
547         struct garp_port *port;
548
549         port = kzalloc(sizeof(*port), GFP_KERNEL);
550         if (!port)
551                 return -ENOMEM;
552         rcu_assign_pointer(dev->garp_port, port);
553         return 0;
554 }
555
556 static void garp_release_port(struct net_device *dev)
557 {
558         struct garp_port *port = rtnl_dereference(dev->garp_port);
559         unsigned int i;
560
561         for (i = 0; i <= GARP_APPLICATION_MAX; i++) {
562                 if (rtnl_dereference(port->applicants[i]))
563                         return;
564         }
565         RCU_INIT_POINTER(dev->garp_port, NULL);
566         kfree_rcu(port, rcu);
567 }
568
569 int garp_init_applicant(struct net_device *dev, struct garp_application *appl)
570 {
571         struct garp_applicant *app;
572         int err;
573
574         ASSERT_RTNL();
575
576         if (!rtnl_dereference(dev->garp_port)) {
577                 err = garp_init_port(dev);
578                 if (err < 0)
579                         goto err1;
580         }
581
582         err = -ENOMEM;
583         app = kzalloc(sizeof(*app), GFP_KERNEL);
584         if (!app)
585                 goto err2;
586
587         err = dev_mc_add(dev, appl->proto.group_address);
588         if (err < 0)
589                 goto err3;
590
591         app->dev = dev;
592         app->app = appl;
593         app->gid = RB_ROOT;
594         spin_lock_init(&app->lock);
595         skb_queue_head_init(&app->queue);
596         rcu_assign_pointer(dev->garp_port->applicants[appl->type], app);
597         timer_setup(&app->join_timer, garp_join_timer, 0);
598         garp_join_timer_arm(app);
599         return 0;
600
601 err3:
602         kfree(app);
603 err2:
604         garp_release_port(dev);
605 err1:
606         return err;
607 }
608 EXPORT_SYMBOL_GPL(garp_init_applicant);
609
610 void garp_uninit_applicant(struct net_device *dev, struct garp_application *appl)
611 {
612         struct garp_port *port = rtnl_dereference(dev->garp_port);
613         struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);
614
615         ASSERT_RTNL();
616
617         RCU_INIT_POINTER(port->applicants[appl->type], NULL);
618
619         /* Delete timer and generate a final TRANSMIT_PDU event to flush out
620          * all pending messages before the applicant is gone. */
621         del_timer_sync(&app->join_timer);
622
623         spin_lock_bh(&app->lock);
624         garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
625         garp_attr_destroy_all(app);
626         garp_pdu_queue(app);
627         spin_unlock_bh(&app->lock);
628
629         garp_queue_xmit(app);
630
631         dev_mc_del(dev, appl->proto.group_address);
632         kfree_rcu(app, rcu);
633         garp_release_port(dev);
634 }
635 EXPORT_SYMBOL_GPL(garp_uninit_applicant);
636
637 int garp_register_application(struct garp_application *appl)
638 {
639         appl->proto.rcv = garp_pdu_rcv;
640         appl->proto.data = appl;
641         return stp_proto_register(&appl->proto);
642 }
643 EXPORT_SYMBOL_GPL(garp_register_application);
644
645 void garp_unregister_application(struct garp_application *appl)
646 {
647         stp_proto_unregister(&appl->proto);
648 }
649 EXPORT_SYMBOL_GPL(garp_unregister_application);