linux/net/802/garp.c
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   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
  24static unsigned int garp_join_time __read_mostly = 200;
  25module_param(garp_join_time, uint, 0644);
  26MODULE_PARM_DESC(garp_join_time, "Join time in ms (default 200ms)");
  27MODULE_LICENSE("GPL");
  28
  29static 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
 140static 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
 150static 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
 170static 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
 189static 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
 205static 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
 211static 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
 233static 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
 241static 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
 259static 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
 267static 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
 279static 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;
 286again:
 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
 310queue:
 311        garp_pdu_queue(app);
 312        goto again;
 313}
 314
 315static 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
 346int 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}
 364EXPORT_SYMBOL_GPL(garp_request_join);
 365
 366void 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}
 383EXPORT_SYMBOL_GPL(garp_request_leave);
 384
 385static 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
 398static 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
 406static 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
 419static 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
 430static 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
 483static 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
 503static 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);
 533err:
 534        kfree_skb(skb);
 535}
 536
 537static 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
 548static 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
 561int 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
 593err3:
 594        kfree(app);
 595err2:
 596        garp_release_port(dev);
 597err1:
 598        return err;
 599}
 600EXPORT_SYMBOL_GPL(garp_init_applicant);
 601
 602void 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}
 622EXPORT_SYMBOL_GPL(garp_uninit_applicant);
 623
 624int 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}
 630EXPORT_SYMBOL_GPL(garp_register_application);
 631
 632void garp_unregister_application(struct garp_application *appl)
 633{
 634        stp_proto_unregister(&appl->proto);
 635}
 636EXPORT_SYMBOL_GPL(garp_unregister_application);
 637
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