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 void garp_attr_destroy_all(struct garp_applicant *app)
 210 {
 211         struct rb_node *node, *next;
 212         struct garp_attr *attr;
 213
 214         for (node = rb_first(&app->gid);
 215              next = node ? rb_next(node) : NULL, node != NULL;
 216              node = next) {
 217                 attr = rb_entry(node, struct garp_attr, node);
 218                 garp_attr_destroy(app, attr);
 219         }
 220 }
 221
 222 static int garp_pdu_init(struct garp_applicant *app)
 223 {
 224         struct sk_buff *skb;
 225         struct garp_pdu_hdr *gp;
 226
 227 #define LLC_RESERVE     sizeof(struct llc_pdu_un)
 228         skb = alloc_skb(app->dev->mtu + LL_RESERVED_SPACE(app->dev),
 229                         GFP_ATOMIC);
 230         if (!skb)
 231                 return -ENOMEM;
 232
 233         skb->dev = app->dev;
 234         skb->protocol = htons(ETH_P_802_2);
 235         skb_reserve(skb, LL_RESERVED_SPACE(app->dev) + LLC_RESERVE);
 236
 237         gp = (struct garp_pdu_hdr *)__skb_put(skb, sizeof(*gp));
 238         put_unaligned(htons(GARP_PROTOCOL_ID), &gp->protocol);
 239
 240         app->pdu = skb;
 241         return 0;
 242 }
 243
 244 static int garp_pdu_append_end_mark(struct garp_applicant *app)
 245 {
 246         if (skb_tailroom(app->pdu) < sizeof(u8))
 247                 return -1;
 248         *(u8 *)__skb_put(app->pdu, sizeof(u8)) = GARP_END_MARK;
 249         return 0;
 250 }
 251
 252 static void garp_pdu_queue(struct garp_applicant *app)
 253 {
 254         if (!app->pdu)
 255                 return;
 256
 257         garp_pdu_append_end_mark(app);
 258         garp_pdu_append_end_mark(app);
 259
 260         llc_pdu_header_init(app->pdu, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
 261                             LLC_SAP_BSPAN, LLC_PDU_CMD);
 262         llc_pdu_init_as_ui_cmd(app->pdu);
 263         llc_mac_hdr_init(app->pdu, app->dev->dev_addr,
 264                          app->app->proto.group_address);
 265
 266         skb_queue_tail(&app->queue, app->pdu);
 267         app->pdu = NULL;
 268 }
 269
 270 static void garp_queue_xmit(struct garp_applicant *app)
 271 {
 272         struct sk_buff *skb;
 273
 274         while ((skb = skb_dequeue(&app->queue)))
 275                 dev_queue_xmit(skb);
 276 }
 277
 278 static int garp_pdu_append_msg(struct garp_applicant *app, u8 attrtype)
 279 {
 280         struct garp_msg_hdr *gm;
 281
 282         if (skb_tailroom(app->pdu) < sizeof(*gm))
 283                 return -1;
 284         gm = (struct garp_msg_hdr *)__skb_put(app->pdu, sizeof(*gm));
 285         gm->attrtype = attrtype;
 286         garp_cb(app->pdu)->cur_type = attrtype;
 287         return 0;
 288 }
 289
 290 static int garp_pdu_append_attr(struct garp_applicant *app,
 291                                 const struct garp_attr *attr,
 292                                 enum garp_attr_event event)
 293 {
 294         struct garp_attr_hdr *ga;
 295         unsigned int len;
 296         int err;
 297 again:
 298         if (!app->pdu) {
 299                 err = garp_pdu_init(app);
 300                 if (err < 0)
 301                         return err;
 302         }
 303
 304         if (garp_cb(app->pdu)->cur_type != attr->type) {
 305                 if (garp_cb(app->pdu)->cur_type &&
 306                     garp_pdu_append_end_mark(app) < 0)
 307                         goto queue;
 308                 if (garp_pdu_append_msg(app, attr->type) < 0)
 309                         goto queue;
 310         }
 311
 312         len = sizeof(*ga) + attr->dlen;
 313         if (skb_tailroom(app->pdu) < len)
 314                 goto queue;
 315         ga = (struct garp_attr_hdr *)__skb_put(app->pdu, len);
 316         ga->len   = len;
 317         ga->event = event;
 318         memcpy(ga->data, attr->data, attr->dlen);
 319         return 0;
 320
 321 queue:
 322         garp_pdu_queue(app);
 323         goto again;
 324 }
 325
 326 static void garp_attr_event(struct garp_applicant *app,
 327                             struct garp_attr *attr, enum garp_event event)
 328 {
 329         enum garp_applicant_state state;
 330
 331         state = garp_applicant_state_table[attr->state][event].state;
 332         if (state == GARP_APPLICANT_INVALID)
 333                 return;
 334
 335         switch (garp_applicant_state_table[attr->state][event].action) {
 336         case GARP_ACTION_NONE:
 337                 break;
 338         case GARP_ACTION_S_JOIN_IN:
 339                 /* When appending the attribute fails, don't update state in
 340                  * order to retry on next TRANSMIT_PDU event. */
 341                 if (garp_pdu_append_attr(app, attr, GARP_JOIN_IN) < 0)
 342                         return;
 343                 break;
 344         case GARP_ACTION_S_LEAVE_EMPTY:
 345                 garp_pdu_append_attr(app, attr, GARP_LEAVE_EMPTY);
 346                 /* As a pure applicant, sending a leave message implies that
 347                  * the attribute was unregistered and can be destroyed. */
 348                 garp_attr_destroy(app, attr);
 349                 return;
 350         default:
 351                 WARN_ON(1);
 352         }
 353
 354         attr->state = state;
 355 }
 356
 357 int garp_request_join(const struct net_device *dev,
 358                       const struct garp_application *appl,
 359                       const void *data, u8 len, u8 type)
 360 {
 361         struct garp_port *port = rtnl_dereference(dev->garp_port);
 362         struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);
 363         struct garp_attr *attr;
 364
 365         spin_lock_bh(&app->lock);
 366         attr = garp_attr_create(app, data, len, type);
 367         if (!attr) {
 368                 spin_unlock_bh(&app->lock);
 369                 return -ENOMEM;
 370         }
 371         garp_attr_event(app, attr, GARP_EVENT_REQ_JOIN);
 372         spin_unlock_bh(&app->lock);
 373         return 0;
 374 }
 375 EXPORT_SYMBOL_GPL(garp_request_join);
 376
 377 void garp_request_leave(const struct net_device *dev,
 378                         const struct garp_application *appl,
 379                         const void *data, u8 len, u8 type)
 380 {
 381         struct garp_port *port = rtnl_dereference(dev->garp_port);
 382         struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);
 383         struct garp_attr *attr;
 384
 385         spin_lock_bh(&app->lock);
 386         attr = garp_attr_lookup(app, data, len, type);
 387         if (!attr) {
 388                 spin_unlock_bh(&app->lock);
 389                 return;
 390         }
 391         garp_attr_event(app, attr, GARP_EVENT_REQ_LEAVE);
 392         spin_unlock_bh(&app->lock);
 393 }
 394 EXPORT_SYMBOL_GPL(garp_request_leave);
 395
 396 static void garp_gid_event(struct garp_applicant *app, enum garp_event event)
 397 {
 398         struct rb_node *node, *next;
 399         struct garp_attr *attr;
 400
 401         for (node = rb_first(&app->gid);
 402              next = node ? rb_next(node) : NULL, node != NULL;
 403              node = next) {
 404                 attr = rb_entry(node, struct garp_attr, node);
 405                 garp_attr_event(app, attr, event);
 406         }
 407 }
 408
 409 static void garp_join_timer_arm(struct garp_applicant *app)
 410 {
 411         unsigned long delay;
 412
 413         delay = (u64)msecs_to_jiffies(garp_join_time) * prandom_u32() >> 32;
 414         mod_timer(&app->join_timer, jiffies + delay);
 415 }
 416
 417 static void garp_join_timer(unsigned long data)
 418 {
 419         struct garp_applicant *app = (struct garp_applicant *)data;
 420
 421         spin_lock(&app->lock);
 422         garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
 423         garp_pdu_queue(app);
 424         spin_unlock(&app->lock);
 425
 426         garp_queue_xmit(app);
 427         garp_join_timer_arm(app);
 428 }
 429
 430 static int garp_pdu_parse_end_mark(struct sk_buff *skb)
 431 {
 432         if (!pskb_may_pull(skb, sizeof(u8)))
 433                 return -1;
 434         if (*skb->data == GARP_END_MARK) {
 435                 skb_pull(skb, sizeof(u8));
 436                 return -1;
 437         }
 438         return 0;
 439 }
 440
 441 static int garp_pdu_parse_attr(struct garp_applicant *app, struct sk_buff *skb,
 442                                u8 attrtype)
 443 {
 444         const struct garp_attr_hdr *ga;
 445         struct garp_attr *attr;
 446         enum garp_event event;
 447         unsigned int dlen;
 448
 449         if (!pskb_may_pull(skb, sizeof(*ga)))
 450                 return -1;
 451         ga = (struct garp_attr_hdr *)skb->data;
 452         if (ga->len < sizeof(*ga))
 453                 return -1;
 454
 455         if (!pskb_may_pull(skb, ga->len))
 456                 return -1;
 457         skb_pull(skb, ga->len);
 458         dlen = sizeof(*ga) - ga->len;
 459
 460         if (attrtype > app->app->maxattr)
 461                 return 0;
 462
 463         switch (ga->event) {
 464         case GARP_LEAVE_ALL:
 465                 if (dlen != 0)
 466                         return -1;
 467                 garp_gid_event(app, GARP_EVENT_R_LEAVE_EMPTY);
 468                 return 0;
 469         case GARP_JOIN_EMPTY:
 470                 event = GARP_EVENT_R_JOIN_EMPTY;
 471                 break;
 472         case GARP_JOIN_IN:
 473                 event = GARP_EVENT_R_JOIN_IN;
 474                 break;
 475         case GARP_LEAVE_EMPTY:
 476                 event = GARP_EVENT_R_LEAVE_EMPTY;
 477                 break;
 478         case GARP_EMPTY:
 479                 event = GARP_EVENT_R_EMPTY;
 480                 break;
 481         default:
 482                 return 0;
 483         }
 484
 485         if (dlen == 0)
 486                 return -1;
 487         attr = garp_attr_lookup(app, ga->data, dlen, attrtype);
 488         if (attr == NULL)
 489                 return 0;
 490         garp_attr_event(app, attr, event);
 491         return 0;
 492 }
 493
 494 static int garp_pdu_parse_msg(struct garp_applicant *app, struct sk_buff *skb)
 495 {
 496         const struct garp_msg_hdr *gm;
 497
 498         if (!pskb_may_pull(skb, sizeof(*gm)))
 499                 return -1;
 500         gm = (struct garp_msg_hdr *)skb->data;
 501         if (gm->attrtype == 0)
 502                 return -1;
 503         skb_pull(skb, sizeof(*gm));
 504
 505         while (skb->len > 0) {
 506                 if (garp_pdu_parse_attr(app, skb, gm->attrtype) < 0)
 507                         return -1;
 508                 if (garp_pdu_parse_end_mark(skb) < 0)
 509                         break;
 510         }
 511         return 0;
 512 }
 513
 514 static void garp_pdu_rcv(const struct stp_proto *proto, struct sk_buff *skb,
 515                          struct net_device *dev)
 516 {
 517         struct garp_application *appl = proto->data;
 518         struct garp_port *port;
 519         struct garp_applicant *app;
 520         const struct garp_pdu_hdr *gp;
 521
 522         port = rcu_dereference(dev->garp_port);
 523         if (!port)
 524                 goto err;
 525         app = rcu_dereference(port->applicants[appl->type]);
 526         if (!app)
 527                 goto err;
 528
 529         if (!pskb_may_pull(skb, sizeof(*gp)))
 530                 goto err;
 531         gp = (struct garp_pdu_hdr *)skb->data;
 532         if (get_unaligned(&gp->protocol) != htons(GARP_PROTOCOL_ID))
 533                 goto err;
 534         skb_pull(skb, sizeof(*gp));
 535
 536         spin_lock(&app->lock);
 537         while (skb->len > 0) {
 538                 if (garp_pdu_parse_msg(app, skb) < 0)
 539                         break;
 540                 if (garp_pdu_parse_end_mark(skb) < 0)
 541                         break;
 542         }
 543         spin_unlock(&app->lock);
 544 err:
 545         kfree_skb(skb);
 546 }
 547
 548 static int garp_init_port(struct net_device *dev)
 549 {
 550         struct garp_port *port;
 551
 552         port = kzalloc(sizeof(*port), GFP_KERNEL);
 553         if (!port)
 554                 return -ENOMEM;
 555         rcu_assign_pointer(dev->garp_port, port);
 556         return 0;
 557 }
 558
 559 static void garp_release_port(struct net_device *dev)
 560 {
 561         struct garp_port *port = rtnl_dereference(dev->garp_port);
 562         unsigned int i;
 563
 564         for (i = 0; i <= GARP_APPLICATION_MAX; i++) {
 565                 if (rtnl_dereference(port->applicants[i]))
 566                         return;
 567         }
 568         RCU_INIT_POINTER(dev->garp_port, NULL);
 569         kfree_rcu(port, rcu);
 570 }
 571
 572 int garp_init_applicant(struct net_device *dev, struct garp_application *appl)
 573 {
 574         struct garp_applicant *app;
 575         int err;
 576
 577         ASSERT_RTNL();
 578
 579         if (!rtnl_dereference(dev->garp_port)) {
 580                 err = garp_init_port(dev);
 581                 if (err < 0)
 582                         goto err1;
 583         }
 584
 585         err = -ENOMEM;
 586         app = kzalloc(sizeof(*app), GFP_KERNEL);
 587         if (!app)
 588                 goto err2;
 589
 590         err = dev_mc_add(dev, appl->proto.group_address);
 591         if (err < 0)
 592                 goto err3;
 593
 594         app->dev = dev;
 595         app->app = appl;
 596         app->gid = RB_ROOT;
 597         spin_lock_init(&app->lock);
 598         skb_queue_head_init(&app->queue);
 599         rcu_assign_pointer(dev->garp_port->applicants[appl->type], app);
 600         setup_timer(&app->join_timer, garp_join_timer, (unsigned long)app);
 601         garp_join_timer_arm(app);
 602         return 0;
 603
 604 err3:
 605         kfree(app);
 606 err2:
 607         garp_release_port(dev);
 608 err1:
 609         return err;
 610 }
 611 EXPORT_SYMBOL_GPL(garp_init_applicant);
 612
 613 void garp_uninit_applicant(struct net_device *dev, struct garp_application *appl)
 614 {
 615         struct garp_port *port = rtnl_dereference(dev->garp_port);
 616         struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);
 617
 618         ASSERT_RTNL();
 619
 620         RCU_INIT_POINTER(port->applicants[appl->type], NULL);
 621
 622         /* Delete timer and generate a final TRANSMIT_PDU event to flush out
 623          * all pending messages before the applicant is gone. */
 624         del_timer_sync(&app->join_timer);
 625
 626         spin_lock_bh(&app->lock);
 627         garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
 628         garp_attr_destroy_all(app);
 629         garp_pdu_queue(app);
 630         spin_unlock_bh(&app->lock);
 631
 632         garp_queue_xmit(app);
 633
 634         dev_mc_del(dev, appl->proto.group_address);
 635         kfree_rcu(app, rcu);
 636         garp_release_port(dev);
 637 }
 638 EXPORT_SYMBOL_GPL(garp_uninit_applicant);
 639
 640 int garp_register_application(struct garp_application *appl)
 641 {
 642         appl->proto.rcv = garp_pdu_rcv;
 643         appl->proto.data = appl;
 644         return stp_proto_register(&appl->proto);
 645 }
 646 EXPORT_SYMBOL_GPL(garp_register_application);
 647
 648 void garp_unregister_application(struct garp_application *appl)
 649 {
 650         stp_proto_unregister(&appl->proto);
 651 }
 652 EXPORT_SYMBOL_GPL(garp_unregister_application);