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 void garp_attr_insert(struct garp_applicant *app, struct garp_attr *new)
 171 {
 172         struct rb_node *parent = NULL, **p = &app->gid.rb_node;
 173         struct garp_attr *attr;
 174         int d;
 175
 176         while (*p) {
 177                 parent = *p;
 178                 attr = rb_entry(parent, struct garp_attr, node);
 179                 d = garp_attr_cmp(attr, new->data, new->dlen, new->type);
 180                 if (d < 0)
 181                         p = &parent->rb_left;
 182                 else if (d > 0)
 183                         p = &parent->rb_right;
 184         }
 185         rb_link_node(&new->node, parent, p);
 186         rb_insert_color(&new->node, &app->gid);
 187 }
 188
 189 static struct garp_attr *garp_attr_create(struct garp_applicant *app,
 190                                           const void *data, u8 len, u8 type)
 191 {
 192         struct garp_attr *attr;
 193
 194         attr = kmalloc(sizeof(*attr) + len, GFP_ATOMIC);
 195         if (!attr)
 196                 return attr;
 197         attr->state = GARP_APPLICANT_VO;
 198         attr->type  = type;
 199         attr->dlen  = len;
 200         memcpy(attr->data, data, len);
 201         garp_attr_insert(app, attr);
 202         return attr;
 203 }
 204
 205 static void garp_attr_destroy(struct garp_applicant *app, struct garp_attr *attr)
 206 {
 207         rb_erase(&attr->node, &app->gid);
 208         kfree(attr);
 209 }
 210
 211 static int garp_pdu_init(struct garp_applicant *app)
 212 {
 213         struct sk_buff *skb;
 214         struct garp_pdu_hdr *gp;
 215
 216 #define LLC_RESERVE     sizeof(struct llc_pdu_un)
 217         skb = alloc_skb(app->dev->mtu + LL_RESERVED_SPACE(app->dev),
 218                         GFP_ATOMIC);
 219         if (!skb)
 220                 return -ENOMEM;
 221
 222         skb->dev = app->dev;
 223         skb->protocol = htons(ETH_P_802_2);
 224         skb_reserve(skb, LL_RESERVED_SPACE(app->dev) + LLC_RESERVE);
 225
 226         gp = (struct garp_pdu_hdr *)__skb_put(skb, sizeof(*gp));
 227         put_unaligned(htons(GARP_PROTOCOL_ID), &gp->protocol);
 228
 229         app->pdu = skb;
 230         return 0;
 231 }
 232
 233 static int garp_pdu_append_end_mark(struct garp_applicant *app)
 234 {
 235         if (skb_tailroom(app->pdu) < sizeof(u8))
 236                 return -1;
 237         *(u8 *)__skb_put(app->pdu, sizeof(u8)) = GARP_END_MARK;
 238         return 0;
 239 }
 240
 241 static void garp_pdu_queue(struct garp_applicant *app)
 242 {
 243         if (!app->pdu)
 244                 return;
 245
 246         garp_pdu_append_end_mark(app);
 247         garp_pdu_append_end_mark(app);
 248
 249         llc_pdu_header_init(app->pdu, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
 250                             LLC_SAP_BSPAN, LLC_PDU_CMD);
 251         llc_pdu_init_as_ui_cmd(app->pdu);
 252         llc_mac_hdr_init(app->pdu, app->dev->dev_addr,
 253                          app->app->proto.group_address);
 254
 255         skb_queue_tail(&app->queue, app->pdu);
 256         app->pdu = NULL;
 257 }
 258
 259 static void garp_queue_xmit(struct garp_applicant *app)
 260 {
 261         struct sk_buff *skb;
 262
 263         while ((skb = skb_dequeue(&app->queue)))
 264                 dev_queue_xmit(skb);
 265 }
 266
 267 static int garp_pdu_append_msg(struct garp_applicant *app, u8 attrtype)
 268 {
 269         struct garp_msg_hdr *gm;
 270
 271         if (skb_tailroom(app->pdu) < sizeof(*gm))
 272                 return -1;
 273         gm = (struct garp_msg_hdr *)__skb_put(app->pdu, sizeof(*gm));
 274         gm->attrtype = attrtype;
 275         garp_cb(app->pdu)->cur_type = attrtype;
 276         return 0;
 277 }
 278
 279 static int garp_pdu_append_attr(struct garp_applicant *app,
 280                                 const struct garp_attr *attr,
 281                                 enum garp_attr_event event)
 282 {
 283         struct garp_attr_hdr *ga;
 284         unsigned int len;
 285         int err;
 286 again:
 287         if (!app->pdu) {
 288                 err = garp_pdu_init(app);
 289                 if (err < 0)
 290                         return err;
 291         }
 292
 293         if (garp_cb(app->pdu)->cur_type != attr->type) {
 294                 if (garp_cb(app->pdu)->cur_type &&
 295                     garp_pdu_append_end_mark(app) < 0)
 296                         goto queue;
 297                 if (garp_pdu_append_msg(app, attr->type) < 0)
 298                         goto queue;
 299         }
 300
 301         len = sizeof(*ga) + attr->dlen;
 302         if (skb_tailroom(app->pdu) < len)
 303                 goto queue;
 304         ga = (struct garp_attr_hdr *)__skb_put(app->pdu, len);
 305         ga->len   = len;
 306         ga->event = event;
 307         memcpy(ga->data, attr->data, attr->dlen);
 308         return 0;
 309
 310 queue:
 311         garp_pdu_queue(app);
 312         goto again;
 313 }
 314
 315 static void garp_attr_event(struct garp_applicant *app,
 316                             struct garp_attr *attr, enum garp_event event)
 317 {
 318         enum garp_applicant_state state;
 319
 320         state = garp_applicant_state_table[attr->state][event].state;
 321         if (state == GARP_APPLICANT_INVALID)
 322                 return;
 323
 324         switch (garp_applicant_state_table[attr->state][event].action) {
 325         case GARP_ACTION_NONE:
 326                 break;
 327         case GARP_ACTION_S_JOIN_IN:
 328                 /* When appending the attribute fails, don't update state in
 329                  * order to retry on next TRANSMIT_PDU event. */
 330                 if (garp_pdu_append_attr(app, attr, GARP_JOIN_IN) < 0)
 331                         return;
 332                 break;
 333         case GARP_ACTION_S_LEAVE_EMPTY:
 334                 garp_pdu_append_attr(app, attr, GARP_LEAVE_EMPTY);
 335                 /* As a pure applicant, sending a leave message implies that
 336                  * the attribute was unregistered and can be destroyed. */
 337                 garp_attr_destroy(app, attr);
 338                 return;
 339         default:
 340                 WARN_ON(1);
 341         }
 342
 343         attr->state = state;
 344 }
 345
 346 int garp_request_join(const struct net_device *dev,
 347                       const struct garp_application *appl,
 348                       const void *data, u8 len, u8 type)
 349 {
 350         struct garp_port *port = rtnl_dereference(dev->garp_port);
 351         struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);
 352         struct garp_attr *attr;
 353
 354         spin_lock_bh(&app->lock);
 355         attr = garp_attr_create(app, data, len, type);
 356         if (!attr) {
 357                 spin_unlock_bh(&app->lock);
 358                 return -ENOMEM;
 359         }
 360         garp_attr_event(app, attr, GARP_EVENT_REQ_JOIN);
 361         spin_unlock_bh(&app->lock);
 362         return 0;
 363 }
 364 EXPORT_SYMBOL_GPL(garp_request_join);
 365
 366 void garp_request_leave(const struct net_device *dev,
 367                         const struct garp_application *appl,
 368                         const void *data, u8 len, u8 type)
 369 {
 370         struct garp_port *port = rtnl_dereference(dev->garp_port);
 371         struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);
 372         struct garp_attr *attr;
 373
 374         spin_lock_bh(&app->lock);
 375         attr = garp_attr_lookup(app, data, len, type);
 376         if (!attr) {
 377                 spin_unlock_bh(&app->lock);
 378                 return;
 379         }
 380         garp_attr_event(app, attr, GARP_EVENT_REQ_LEAVE);
 381         spin_unlock_bh(&app->lock);
 382 }
 383 EXPORT_SYMBOL_GPL(garp_request_leave);
 384
 385 static void garp_gid_event(struct garp_applicant *app, enum garp_event event)
 386 {
 387         struct rb_node *node, *next;
 388         struct garp_attr *attr;
 389
 390         for (node = rb_first(&app->gid);
 391              next = node ? rb_next(node) : NULL, node != NULL;
 392              node = next) {
 393                 attr = rb_entry(node, struct garp_attr, node);
 394                 garp_attr_event(app, attr, event);
 395         }
 396 }
 397
 398 static void garp_join_timer_arm(struct garp_applicant *app)
 399 {
 400         unsigned long delay;
 401
 402         delay = (u64)msecs_to_jiffies(garp_join_time) * net_random() >> 32;
 403         mod_timer(&app->join_timer, jiffies + delay);
 404 }
 405
 406 static void garp_join_timer(unsigned long data)
 407 {
 408         struct garp_applicant *app = (struct garp_applicant *)data;
 409
 410         spin_lock(&app->lock);
 411         garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
 412         garp_pdu_queue(app);
 413         spin_unlock(&app->lock);
 414
 415         garp_queue_xmit(app);
 416         garp_join_timer_arm(app);
 417 }
 418
 419 static int garp_pdu_parse_end_mark(struct sk_buff *skb)
 420 {
 421         if (!pskb_may_pull(skb, sizeof(u8)))
 422                 return -1;
 423         if (*skb->data == GARP_END_MARK) {
 424                 skb_pull(skb, sizeof(u8));
 425                 return -1;
 426         }
 427         return 0;
 428 }
 429
 430 static int garp_pdu_parse_attr(struct garp_applicant *app, struct sk_buff *skb,
 431                                u8 attrtype)
 432 {
 433         const struct garp_attr_hdr *ga;
 434         struct garp_attr *attr;
 435         enum garp_event event;
 436         unsigned int dlen;
 437
 438         if (!pskb_may_pull(skb, sizeof(*ga)))
 439                 return -1;
 440         ga = (struct garp_attr_hdr *)skb->data;
 441         if (ga->len < sizeof(*ga))
 442                 return -1;
 443
 444         if (!pskb_may_pull(skb, ga->len))
 445                 return -1;
 446         skb_pull(skb, ga->len);
 447         dlen = sizeof(*ga) - ga->len;
 448
 449         if (attrtype > app->app->maxattr)
 450                 return 0;
 451
 452         switch (ga->event) {
 453         case GARP_LEAVE_ALL:
 454                 if (dlen != 0)
 455                         return -1;
 456                 garp_gid_event(app, GARP_EVENT_R_LEAVE_EMPTY);
 457                 return 0;
 458         case GARP_JOIN_EMPTY:
 459                 event = GARP_EVENT_R_JOIN_EMPTY;
 460                 break;
 461         case GARP_JOIN_IN:
 462                 event = GARP_EVENT_R_JOIN_IN;
 463                 break;
 464         case GARP_LEAVE_EMPTY:
 465                 event = GARP_EVENT_R_LEAVE_EMPTY;
 466                 break;
 467         case GARP_EMPTY:
 468                 event = GARP_EVENT_R_EMPTY;
 469                 break;
 470         default:
 471                 return 0;
 472         }
 473
 474         if (dlen == 0)
 475                 return -1;
 476         attr = garp_attr_lookup(app, ga->data, dlen, attrtype);
 477         if (attr == NULL)
 478                 return 0;
 479         garp_attr_event(app, attr, event);
 480         return 0;
 481 }
 482
 483 static int garp_pdu_parse_msg(struct garp_applicant *app, struct sk_buff *skb)
 484 {
 485         const struct garp_msg_hdr *gm;
 486
 487         if (!pskb_may_pull(skb, sizeof(*gm)))
 488                 return -1;
 489         gm = (struct garp_msg_hdr *)skb->data;
 490         if (gm->attrtype == 0)
 491                 return -1;
 492         skb_pull(skb, sizeof(*gm));
 493
 494         while (skb->len > 0) {
 495                 if (garp_pdu_parse_attr(app, skb, gm->attrtype) < 0)
 496                         return -1;
 497                 if (garp_pdu_parse_end_mark(skb) < 0)
 498                         break;
 499         }
 500         return 0;
 501 }
 502
 503 static void garp_pdu_rcv(const struct stp_proto *proto, struct sk_buff *skb,
 504                          struct net_device *dev)
 505 {
 506         struct garp_application *appl = proto->data;
 507         struct garp_port *port;
 508         struct garp_applicant *app;
 509         const struct garp_pdu_hdr *gp;
 510
 511         port = rcu_dereference(dev->garp_port);
 512         if (!port)
 513                 goto err;
 514         app = rcu_dereference(port->applicants[appl->type]);
 515         if (!app)
 516                 goto err;
 517
 518         if (!pskb_may_pull(skb, sizeof(*gp)))
 519                 goto err;
 520         gp = (struct garp_pdu_hdr *)skb->data;
 521         if (get_unaligned(&gp->protocol) != htons(GARP_PROTOCOL_ID))
 522                 goto err;
 523         skb_pull(skb, sizeof(*gp));
 524
 525         spin_lock(&app->lock);
 526         while (skb->len > 0) {
 527                 if (garp_pdu_parse_msg(app, skb) < 0)
 528                         break;
 529                 if (garp_pdu_parse_end_mark(skb) < 0)
 530                         break;
 531         }
 532         spin_unlock(&app->lock);
 533 err:
 534         kfree_skb(skb);
 535 }
 536
 537 static int garp_init_port(struct net_device *dev)
 538 {
 539         struct garp_port *port;
 540
 541         port = kzalloc(sizeof(*port), GFP_KERNEL);
 542         if (!port)
 543                 return -ENOMEM;
 544         rcu_assign_pointer(dev->garp_port, port);
 545         return 0;
 546 }
 547
 548 static void garp_release_port(struct net_device *dev)
 549 {
 550         struct garp_port *port = rtnl_dereference(dev->garp_port);
 551         unsigned int i;
 552
 553         for (i = 0; i <= GARP_APPLICATION_MAX; i++) {
 554                 if (rtnl_dereference(port->applicants[i]))
 555                         return;
 556         }
 557         RCU_INIT_POINTER(dev->garp_port, NULL);
 558         kfree_rcu(port, rcu);
 559 }
 560
 561 int garp_init_applicant(struct net_device *dev, struct garp_application *appl)
 562 {
 563         struct garp_applicant *app;
 564         int err;
 565
 566         ASSERT_RTNL();
 567
 568         if (!rtnl_dereference(dev->garp_port)) {
 569                 err = garp_init_port(dev);
 570                 if (err < 0)
 571                         goto err1;
 572         }
 573
 574         err = -ENOMEM;
 575         app = kzalloc(sizeof(*app), GFP_KERNEL);
 576         if (!app)
 577                 goto err2;
 578
 579         err = dev_mc_add(dev, appl->proto.group_address);
 580         if (err < 0)
 581                 goto err3;
 582
 583         app->dev = dev;
 584         app->app = appl;
 585         app->gid = RB_ROOT;
 586         spin_lock_init(&app->lock);
 587         skb_queue_head_init(&app->queue);
 588         rcu_assign_pointer(dev->garp_port->applicants[appl->type], app);
 589         setup_timer(&app->join_timer, garp_join_timer, (unsigned long)app);
 590         garp_join_timer_arm(app);
 591         return 0;
 592
 593 err3:
 594         kfree(app);
 595 err2:
 596         garp_release_port(dev);
 597 err1:
 598         return err;
 599 }
 600 EXPORT_SYMBOL_GPL(garp_init_applicant);
 601
 602 void garp_uninit_applicant(struct net_device *dev, struct garp_application *appl)
 603 {
 604         struct garp_port *port = rtnl_dereference(dev->garp_port);
 605         struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);
 606
 607         ASSERT_RTNL();
 608
 609         RCU_INIT_POINTER(port->applicants[appl->type], NULL);
 610
 611         /* Delete timer and generate a final TRANSMIT_PDU event to flush out
 612          * all pending messages before the applicant is gone. */
 613         del_timer_sync(&app->join_timer);
 614         garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
 615         garp_pdu_queue(app);
 616         garp_queue_xmit(app);
 617
 618         dev_mc_del(dev, appl->proto.group_address);
 619         kfree_rcu(app, rcu);
 620         garp_release_port(dev);
 621 }
 622 EXPORT_SYMBOL_GPL(garp_uninit_applicant);
 623
 624 int garp_register_application(struct garp_application *appl)
 625 {
 626         appl->proto.rcv = garp_pdu_rcv;
 627         appl->proto.data = appl;
 628         return stp_proto_register(&appl->proto);
 629 }
 630 EXPORT_SYMBOL_GPL(garp_register_application);
 631
 632 void garp_unregister_application(struct garp_application *appl)
 633 {
 634         stp_proto_unregister(&appl->proto);
 635 }
 636 EXPORT_SYMBOL_GPL(garp_unregister_application);