net/netfilter/nfnetlink_cthelper.c

   1 /*
   2  * (C) 2012 Pablo Neira Ayuso <pablo@netfilter.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation (or any later at your option).
   7  *
   8  * This software has been sponsored by Vyatta Inc. <http://www.vyatta.com>
   9  */
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12 #include <linux/kernel.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/netlink.h>
  15 #include <linux/rculist.h>
  16 #include <linux/slab.h>
  17 #include <linux/types.h>
  18 #include <linux/list.h>
  19 #include <linux/errno.h>
  20 #include <net/netlink.h>
  21 #include <net/sock.h>
  22
  23 #include <net/netfilter/nf_conntrack_helper.h>
  24 #include <net/netfilter/nf_conntrack_expect.h>
  25 #include <net/netfilter/nf_conntrack_ecache.h>
  26
  27 #include <linux/netfilter/nfnetlink.h>
  28 #include <linux/netfilter/nfnetlink_conntrack.h>
  29 #include <linux/netfilter/nfnetlink_cthelper.h>
  30
  31 MODULE_LICENSE("GPL");
  32 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
  33 MODULE_DESCRIPTION("nfnl_cthelper: User-space connection tracking helpers");
  34
  35 static int
  36 nfnl_userspace_cthelper(struct sk_buff *skb, unsigned int protoff,
  37                         struct nf_conn *ct, enum ip_conntrack_info ctinfo)
  38 {
  39         const struct nf_conn_help *help;
  40         struct nf_conntrack_helper *helper;
  41
  42         help = nfct_help(ct);
  43         if (help == NULL)
  44                 return NF_DROP;
  45
  46         /* rcu_read_lock()ed by nf_hook_slow */
  47         helper = rcu_dereference(help->helper);
  48         if (helper == NULL)
  49                 return NF_DROP;
  50
  51         /* This is an user-space helper not yet configured, skip. */
  52         if ((helper->flags &
  53             (NF_CT_HELPER_F_USERSPACE | NF_CT_HELPER_F_CONFIGURED)) ==
  54              NF_CT_HELPER_F_USERSPACE)
  55                 return NF_ACCEPT;
  56
  57         /* If the user-space helper is not available, don't block traffic. */
  58         return NF_QUEUE_NR(helper->queue_num) | NF_VERDICT_FLAG_QUEUE_BYPASS;
  59 }
  60
  61 static const struct nla_policy nfnl_cthelper_tuple_pol[NFCTH_TUPLE_MAX+1] = {
  62         [NFCTH_TUPLE_L3PROTONUM] = { .type = NLA_U16, },
  63         [NFCTH_TUPLE_L4PROTONUM] = { .type = NLA_U8, },
  64 };
  65
  66 static int
  67 nfnl_cthelper_parse_tuple(struct nf_conntrack_tuple *tuple,
  68                           const struct nlattr *attr)
  69 {
  70         struct nlattr *tb[NFCTH_TUPLE_MAX+1];
  71
  72         nla_parse_nested(tb, NFCTH_TUPLE_MAX, attr, nfnl_cthelper_tuple_pol);
  73
  74         if (!tb[NFCTH_TUPLE_L3PROTONUM] || !tb[NFCTH_TUPLE_L4PROTONUM])
  75                 return -EINVAL;
  76
  77         tuple->src.l3num = ntohs(nla_get_be16(tb[NFCTH_TUPLE_L3PROTONUM]));
  78         tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]);
  79
  80         return 0;
  81 }
  82
  83 static int
  84 nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
  85 {
  86         const struct nf_conn_help *help = nfct_help(ct);
  87
  88         if (attr == NULL)
  89                 return -EINVAL;
  90
  91         if (help->helper->data_len == 0)
  92                 return -EINVAL;
  93
  94         memcpy(&help->data, nla_data(attr), help->helper->data_len);
  95         return 0;
  96 }
  97
  98 static int
  99 nfnl_cthelper_to_nlattr(struct sk_buff *skb, const struct nf_conn *ct)
 100 {
 101         const struct nf_conn_help *help = nfct_help(ct);
 102
 103         if (help->helper->data_len &&
 104             nla_put(skb, CTA_HELP_INFO, help->helper->data_len, &help->data))
 105                 goto nla_put_failure;
 106
 107         return 0;
 108
 109 nla_put_failure:
 110         return -ENOSPC;
 111 }
 112
 113 static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = {
 114         [NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING,
 115                                 .len = NF_CT_HELPER_NAME_LEN-1 },
 116         [NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, },
 117         [NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, },
 118 };
 119
 120 static int
 121 nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy,
 122                             const struct nlattr *attr)
 123 {
 124         struct nlattr *tb[NFCTH_POLICY_MAX+1];
 125
 126         nla_parse_nested(tb, NFCTH_POLICY_MAX, attr, nfnl_cthelper_expect_pol);
 127
 128         if (!tb[NFCTH_POLICY_NAME] ||
 129             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 130             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 131                 return -EINVAL;
 132
 133         strncpy(expect_policy->name,
 134                 nla_data(tb[NFCTH_POLICY_NAME]), NF_CT_HELPER_NAME_LEN);
 135         expect_policy->max_expected =
 136                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 137         expect_policy->timeout =
 138                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 139
 140         return 0;
 141 }
 142
 143 static const struct nla_policy
 144 nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
 145         [NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, },
 146 };
 147
 148 static int
 149 nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper,
 150                                   const struct nlattr *attr)
 151 {
 152         int i, ret;
 153         struct nf_conntrack_expect_policy *expect_policy;
 154         struct nlattr *tb[NFCTH_POLICY_SET_MAX+1];
 155
 156         nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
 157                                         nfnl_cthelper_expect_policy_set);
 158
 159         if (!tb[NFCTH_POLICY_SET_NUM])
 160                 return -EINVAL;
 161
 162         helper->expect_class_max =
 163                 ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 164
 165         if (helper->expect_class_max != 0 &&
 166             helper->expect_class_max > NF_CT_MAX_EXPECT_CLASSES)
 167                 return -EOVERFLOW;
 168
 169         expect_policy = kzalloc(sizeof(struct nf_conntrack_expect_policy) *
 170                                 helper->expect_class_max, GFP_KERNEL);
 171         if (expect_policy == NULL)
 172                 return -ENOMEM;
 173
 174         for (i=0; i<helper->expect_class_max; i++) {
 175                 if (!tb[NFCTH_POLICY_SET+i])
 176                         goto err;
 177
 178                 ret = nfnl_cthelper_expect_policy(&expect_policy[i],
 179                                                   tb[NFCTH_POLICY_SET+i]);
 180                 if (ret < 0)
 181                         goto err;
 182         }
 183         helper->expect_policy = expect_policy;
 184         return 0;
 185 err:
 186         kfree(expect_policy);
 187         return -EINVAL;
 188 }
 189
 190 static int
 191 nfnl_cthelper_create(const struct nlattr * const tb[],
 192                      struct nf_conntrack_tuple *tuple)
 193 {
 194         struct nf_conntrack_helper *helper;
 195         int ret;
 196
 197         if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
 198                 return -EINVAL;
 199
 200         helper = kzalloc(sizeof(struct nf_conntrack_helper), GFP_KERNEL);
 201         if (helper == NULL)
 202                 return -ENOMEM;
 203
 204         ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
 205         if (ret < 0)
 206                 goto err;
 207
 208         strncpy(helper->name, nla_data(tb[NFCTH_NAME]), NF_CT_HELPER_NAME_LEN);
 209         helper->data_len = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
 210         helper->flags |= NF_CT_HELPER_F_USERSPACE;
 211         memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
 212
 213         helper->me = THIS_MODULE;
 214         helper->help = nfnl_userspace_cthelper;
 215         helper->from_nlattr = nfnl_cthelper_from_nlattr;
 216         helper->to_nlattr = nfnl_cthelper_to_nlattr;
 217
 218         /* Default to queue number zero, this can be updated at any time. */
 219         if (tb[NFCTH_QUEUE_NUM])
 220                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 221
 222         if (tb[NFCTH_STATUS]) {
 223                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 224
 225                 switch(status) {
 226                 case NFCT_HELPER_STATUS_ENABLED:
 227                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 228                         break;
 229                 case NFCT_HELPER_STATUS_DISABLED:
 230                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 231                         break;
 232                 }
 233         }
 234
 235         ret = nf_conntrack_helper_register(helper);
 236         if (ret < 0)
 237                 goto err;
 238
 239         return 0;
 240 err:
 241         kfree(helper);
 242         return ret;
 243 }
 244
 245 static int
 246 nfnl_cthelper_update(const struct nlattr * const tb[],
 247                      struct nf_conntrack_helper *helper)
 248 {
 249         int ret;
 250
 251         if (tb[NFCTH_PRIV_DATA_LEN])
 252                 return -EBUSY;
 253
 254         if (tb[NFCTH_POLICY]) {
 255                 ret = nfnl_cthelper_parse_expect_policy(helper,
 256                                                         tb[NFCTH_POLICY]);
 257                 if (ret < 0)
 258                         return ret;
 259         }
 260         if (tb[NFCTH_QUEUE_NUM])
 261                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 262
 263         if (tb[NFCTH_STATUS]) {
 264                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 265
 266                 switch(status) {
 267                 case NFCT_HELPER_STATUS_ENABLED:
 268                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 269                         break;
 270                 case NFCT_HELPER_STATUS_DISABLED:
 271                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 272                         break;
 273                 }
 274         }
 275         return 0;
 276 }
 277
 278 static int
 279 nfnl_cthelper_new(struct sock *nfnl, struct sk_buff *skb,
 280                   const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 281 {
 282         const char *helper_name;
 283         struct nf_conntrack_helper *cur, *helper = NULL;
 284         struct nf_conntrack_tuple tuple;
 285         int ret = 0, i;
 286
 287         if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
 288                 return -EINVAL;
 289
 290         helper_name = nla_data(tb[NFCTH_NAME]);
 291
 292         ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 293         if (ret < 0)
 294                 return ret;
 295
 296         rcu_read_lock();
 297         for (i = 0; i < nf_ct_helper_hsize && !helper; i++) {
 298                 hlist_for_each_entry_rcu(cur, &nf_ct_helper_hash[i], hnode) {
 299
 300                         /* skip non-userspace conntrack helpers. */
 301                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 302                                 continue;
 303
 304                         if (strncmp(cur->name, helper_name,
 305                                         NF_CT_HELPER_NAME_LEN) != 0)
 306                                 continue;
 307
 308                         if ((tuple.src.l3num != cur->tuple.src.l3num ||
 309                              tuple.dst.protonum != cur->tuple.dst.protonum))
 310                                 continue;
 311
 312                         if (nlh->nlmsg_flags & NLM_F_EXCL) {
 313                                 ret = -EEXIST;
 314                                 goto err;
 315                         }
 316                         helper = cur;
 317                         break;
 318                 }
 319         }
 320         rcu_read_unlock();
 321
 322         if (helper == NULL)
 323                 ret = nfnl_cthelper_create(tb, &tuple);
 324         else
 325                 ret = nfnl_cthelper_update(tb, helper);
 326
 327         return ret;
 328 err:
 329         rcu_read_unlock();
 330         return ret;
 331 }
 332
 333 static int
 334 nfnl_cthelper_dump_tuple(struct sk_buff *skb,
 335                          struct nf_conntrack_helper *helper)
 336 {
 337         struct nlattr *nest_parms;
 338
 339         nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
 340         if (nest_parms == NULL)
 341                 goto nla_put_failure;
 342
 343         if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
 344                          htons(helper->tuple.src.l3num)))
 345                 goto nla_put_failure;
 346
 347         if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
 348                 goto nla_put_failure;
 349
 350         nla_nest_end(skb, nest_parms);
 351         return 0;
 352
 353 nla_put_failure:
 354         return -1;
 355 }
 356
 357 static int
 358 nfnl_cthelper_dump_policy(struct sk_buff *skb,
 359                         struct nf_conntrack_helper *helper)
 360 {
 361         int i;
 362         struct nlattr *nest_parms1, *nest_parms2;
 363
 364         nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
 365         if (nest_parms1 == NULL)
 366                 goto nla_put_failure;
 367
 368         if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
 369                          htonl(helper->expect_class_max)))
 370                 goto nla_put_failure;
 371
 372         for (i=0; i<helper->expect_class_max; i++) {
 373                 nest_parms2 = nla_nest_start(skb,
 374                                 (NFCTH_POLICY_SET+i) | NLA_F_NESTED);
 375                 if (nest_parms2 == NULL)
 376                         goto nla_put_failure;
 377
 378                 if (nla_put_string(skb, NFCTH_POLICY_NAME,
 379                                    helper->expect_policy[i].name))
 380                         goto nla_put_failure;
 381
 382                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
 383                                  htonl(helper->expect_policy[i].max_expected)))
 384                         goto nla_put_failure;
 385
 386                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
 387                                  htonl(helper->expect_policy[i].timeout)))
 388                         goto nla_put_failure;
 389
 390                 nla_nest_end(skb, nest_parms2);
 391         }
 392         nla_nest_end(skb, nest_parms1);
 393         return 0;
 394
 395 nla_put_failure:
 396         return -1;
 397 }
 398
 399 static int
 400 nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 401                         int event, struct nf_conntrack_helper *helper)
 402 {
 403         struct nlmsghdr *nlh;
 404         struct nfgenmsg *nfmsg;
 405         unsigned int flags = portid ? NLM_F_MULTI : 0;
 406         int status;
 407
 408         event |= NFNL_SUBSYS_CTHELPER << 8;
 409         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 410         if (nlh == NULL)
 411                 goto nlmsg_failure;
 412
 413         nfmsg = nlmsg_data(nlh);
 414         nfmsg->nfgen_family = AF_UNSPEC;
 415         nfmsg->version = NFNETLINK_V0;
 416         nfmsg->res_id = 0;
 417
 418         if (nla_put_string(skb, NFCTH_NAME, helper->name))
 419                 goto nla_put_failure;
 420
 421         if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
 422                 goto nla_put_failure;
 423
 424         if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
 425                 goto nla_put_failure;
 426
 427         if (nfnl_cthelper_dump_policy(skb, helper) < 0)
 428                 goto nla_put_failure;
 429
 430         if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
 431                 goto nla_put_failure;
 432
 433         if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
 434                 status = NFCT_HELPER_STATUS_ENABLED;
 435         else
 436                 status = NFCT_HELPER_STATUS_DISABLED;
 437
 438         if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
 439                 goto nla_put_failure;
 440
 441         nlmsg_end(skb, nlh);
 442         return skb->len;
 443
 444 nlmsg_failure:
 445 nla_put_failure:
 446         nlmsg_cancel(skb, nlh);
 447         return -1;
 448 }
 449
 450 static int
 451 nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
 452 {
 453         struct nf_conntrack_helper *cur, *last;
 454
 455         rcu_read_lock();
 456         last = (struct nf_conntrack_helper *)cb->args[1];
 457         for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
 458 restart:
 459                 hlist_for_each_entry_rcu(cur,
 460                                 &nf_ct_helper_hash[cb->args[0]], hnode) {
 461
 462                         /* skip non-userspace conntrack helpers. */
 463                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 464                                 continue;
 465
 466                         if (cb->args[1]) {
 467                                 if (cur != last)
 468                                         continue;
 469                                 cb->args[1] = 0;
 470                         }
 471                         if (nfnl_cthelper_fill_info(skb,
 472                                             NETLINK_CB(cb->skb).portid,
 473                                             cb->nlh->nlmsg_seq,
 474                                             NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 475                                             NFNL_MSG_CTHELPER_NEW, cur) < 0) {
 476                                 cb->args[1] = (unsigned long)cur;
 477                                 goto out;
 478                         }
 479                 }
 480         }
 481         if (cb->args[1]) {
 482                 cb->args[1] = 0;
 483                 goto restart;
 484         }
 485 out:
 486         rcu_read_unlock();
 487         return skb->len;
 488 }
 489
 490 static int
 491 nfnl_cthelper_get(struct sock *nfnl, struct sk_buff *skb,
 492                   const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 493 {
 494         int ret = -ENOENT, i;
 495         struct nf_conntrack_helper *cur;
 496         struct sk_buff *skb2;
 497         char *helper_name = NULL;
 498         struct nf_conntrack_tuple tuple;
 499         bool tuple_set = false;
 500
 501         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 502                 struct netlink_dump_control c = {
 503                         .dump = nfnl_cthelper_dump_table,
 504                 };
 505                 return netlink_dump_start(nfnl, skb, nlh, &c);
 506         }
 507
 508         if (tb[NFCTH_NAME])
 509                 helper_name = nla_data(tb[NFCTH_NAME]);
 510
 511         if (tb[NFCTH_TUPLE]) {
 512                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 513                 if (ret < 0)
 514                         return ret;
 515
 516                 tuple_set = true;
 517         }
 518
 519         for (i = 0; i < nf_ct_helper_hsize; i++) {
 520                 hlist_for_each_entry_rcu(cur, &nf_ct_helper_hash[i], hnode) {
 521
 522                         /* skip non-userspace conntrack helpers. */
 523                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 524                                 continue;
 525
 526                         if (helper_name && strncmp(cur->name, helper_name,
 527                                                 NF_CT_HELPER_NAME_LEN) != 0) {
 528                                 continue;
 529                         }
 530                         if (tuple_set &&
 531                             (tuple.src.l3num != cur->tuple.src.l3num ||
 532                              tuple.dst.protonum != cur->tuple.dst.protonum))
 533                                 continue;
 534
 535                         skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 536                         if (skb2 == NULL) {
 537                                 ret = -ENOMEM;
 538                                 break;
 539                         }
 540
 541                         ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
 542                                                 nlh->nlmsg_seq,
 543                                                 NFNL_MSG_TYPE(nlh->nlmsg_type),
 544                                                 NFNL_MSG_CTHELPER_NEW, cur);
 545                         if (ret <= 0) {
 546                                 kfree_skb(skb2);
 547                                 break;
 548                         }
 549
 550                         ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 551                                                 MSG_DONTWAIT);
 552                         if (ret > 0)
 553                                 ret = 0;
 554
 555                         /* this avoids a loop in nfnetlink. */
 556                         return ret == -EAGAIN ? -ENOBUFS : ret;
 557                 }
 558         }
 559         return ret;
 560 }
 561
 562 static int
 563 nfnl_cthelper_del(struct sock *nfnl, struct sk_buff *skb,
 564              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 565 {
 566         char *helper_name = NULL;
 567         struct nf_conntrack_helper *cur;
 568         struct hlist_node *tmp;
 569         struct nf_conntrack_tuple tuple;
 570         bool tuple_set = false, found = false;
 571         int i, j = 0, ret;
 572
 573         if (tb[NFCTH_NAME])
 574                 helper_name = nla_data(tb[NFCTH_NAME]);
 575
 576         if (tb[NFCTH_TUPLE]) {
 577                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 578                 if (ret < 0)
 579                         return ret;
 580
 581                 tuple_set = true;
 582         }
 583
 584         for (i = 0; i < nf_ct_helper_hsize; i++) {
 585                 hlist_for_each_entry_safe(cur, tmp, &nf_ct_helper_hash[i],
 586                                                                 hnode) {
 587                         /* skip non-userspace conntrack helpers. */
 588                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 589                                 continue;
 590
 591                         j++;
 592
 593                         if (helper_name && strncmp(cur->name, helper_name,
 594                                                 NF_CT_HELPER_NAME_LEN) != 0) {
 595                                 continue;
 596                         }
 597                         if (tuple_set &&
 598                             (tuple.src.l3num != cur->tuple.src.l3num ||
 599                              tuple.dst.protonum != cur->tuple.dst.protonum))
 600                                 continue;
 601
 602                         found = true;
 603                         nf_conntrack_helper_unregister(cur);
 604                 }
 605         }
 606         /* Make sure we return success if we flush and there is no helpers */
 607         return (found || j == 0) ? 0 : -ENOENT;
 608 }
 609
 610 static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
 611         [NFCTH_NAME] = { .type = NLA_NUL_STRING,
 612                          .len = NF_CT_HELPER_NAME_LEN-1 },
 613         [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
 614 };
 615
 616 static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
 617         [NFNL_MSG_CTHELPER_NEW]         = { .call = nfnl_cthelper_new,
 618                                             .attr_count = NFCTH_MAX,
 619                                             .policy = nfnl_cthelper_policy },
 620         [NFNL_MSG_CTHELPER_GET]         = { .call = nfnl_cthelper_get,
 621                                             .attr_count = NFCTH_MAX,
 622                                             .policy = nfnl_cthelper_policy },
 623         [NFNL_MSG_CTHELPER_DEL]         = { .call = nfnl_cthelper_del,
 624                                             .attr_count = NFCTH_MAX,
 625                                             .policy = nfnl_cthelper_policy },
 626 };
 627
 628 static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
 629         .name                           = "cthelper",
 630         .subsys_id                      = NFNL_SUBSYS_CTHELPER,
 631         .cb_count                       = NFNL_MSG_CTHELPER_MAX,
 632         .cb                             = nfnl_cthelper_cb,
 633 };
 634
 635 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
 636
 637 static int __init nfnl_cthelper_init(void)
 638 {
 639         int ret;
 640
 641         ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
 642         if (ret < 0) {
 643                 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
 644                 goto err_out;
 645         }
 646         return 0;
 647 err_out:
 648         return ret;
 649 }
 650
 651 static void __exit nfnl_cthelper_exit(void)
 652 {
 653         struct nf_conntrack_helper *cur;
 654         struct hlist_node *tmp;
 655         int i;
 656
 657         nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
 658
 659         for (i=0; i<nf_ct_helper_hsize; i++) {
 660                 hlist_for_each_entry_safe(cur, tmp, &nf_ct_helper_hash[i],
 661                                                                         hnode) {
 662                         /* skip non-userspace conntrack helpers. */
 663                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 664                                 continue;
 665
 666                         nf_conntrack_helper_unregister(cur);
 667                 }
 668         }
 669 }
 670
 671 module_init(nfnl_cthelper_init);
 672 module_exit(nfnl_cthelper_exit);