net/802/garp.c

   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
  24 static unsigned int garp_join_time __read_mostly = 200;
  25 module_param(garp_join_time, uint, 0644);
  26 MODULE_PARM_DESC(garp_join_time, "Join time in ms (default 200ms)");
  27 MODULE_LICENSE("GPL");
  28
  29 static 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
 140 static 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
 150 static 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
 170 static 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
 203 static 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
 209 static 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
 231 static 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
 239 static 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
 257 static 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
 265 static 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
 277 static 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;
 284 again:
 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
 308 queue:
 309         garp_pdu_queue(app);
 310         goto again;
 311 }
 312
 313 static 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
 344 int 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 }
 362 EXPORT_SYMBOL_GPL(garp_request_join);
 363
 364 void 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 }
 381 EXPORT_SYMBOL_GPL(garp_request_leave);
 382
 383 static 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
 396 static void garp_join_timer_arm(struct garp_applicant *app)
 397 {
 398         unsigned long delay;
 399
 400         delay = (u64)msecs_to_jiffies(garp_join_time) * net_random() >> 32;
 401         mod_timer(&app->join_timer, jiffies + delay);
 402 }
 403
 404 static 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
 417 static 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
 428 static 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
 481 static 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
 501 static 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);
 531 err:
 532         kfree_skb(skb);
 533 }
 534
 535 static 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
 546 static 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
 559 int 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
 591 err3:
 592         kfree(app);
 593 err2:
 594         garp_release_port(dev);
 595 err1:
 596         return err;
 597 }
 598 EXPORT_SYMBOL_GPL(garp_init_applicant);
 599
 600 void 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 }
 624 EXPORT_SYMBOL_GPL(garp_uninit_applicant);
 625
 626 int 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 }
 632 EXPORT_SYMBOL_GPL(garp_register_application);
 633
 634 void garp_unregister_application(struct garp_application *appl)
 635 {
 636         stp_proto_unregister(&appl->proto);
 637 }
 638 EXPORT_SYMBOL_GPL(garp_unregister_application);