linux/net/802/garp.c
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   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
  21static unsigned int garp_join_time __read_mostly = 200;
  22module_param(garp_join_time, uint, 0644);
  23MODULE_PARM_DESC(garp_join_time, "Join time in ms (default 200ms)");
  24MODULE_LICENSE("GPL");
  25
  26static 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
 137static 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
 147static 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
 167static 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
 200static 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
 206static 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
 219static 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
 241static 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
 249static 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
 267static 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
 275static 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
 287static 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;
 294again:
 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
 318queue:
 319        garp_pdu_queue(app);
 320        goto again;
 321}
 322
 323static 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
 354int 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}
 372EXPORT_SYMBOL_GPL(garp_request_join);
 373
 374void 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}
 391EXPORT_SYMBOL_GPL(garp_request_leave);
 392
 393static 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
 406static 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
 414static 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
 427static 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
 438static 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
 491static 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
 511static 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);
 541err:
 542        kfree_skb(skb);
 543}
 544
 545static 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
 556static 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
 569int 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
 601err3:
 602        kfree(app);
 603err2:
 604        garp_release_port(dev);
 605err1:
 606        return err;
 607}
 608EXPORT_SYMBOL_GPL(garp_init_applicant);
 609
 610void 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}
 635EXPORT_SYMBOL_GPL(garp_uninit_applicant);
 636
 637int 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}
 643EXPORT_SYMBOL_GPL(garp_register_application);
 644
 645void garp_unregister_application(struct garp_application *appl)
 646{
 647        stp_proto_unregister(&appl->proto);
 648}
 649EXPORT_SYMBOL_GPL(garp_unregister_application);
 650