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);