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 struct nfnl_cthelper {
  36         struct list_head                list;
  37         struct nf_conntrack_helper      helper;
  38 };
  39
  40 static LIST_HEAD(nfnl_cthelper_list);
  41
  42 static int
  43 nfnl_userspace_cthelper(struct sk_buff *skb, unsigned int protoff,
  44                         struct nf_conn *ct, enum ip_conntrack_info ctinfo)
  45 {
  46         const struct nf_conn_help *help;
  47         struct nf_conntrack_helper *helper;
  48
  49         help = nfct_help(ct);
  50         if (help == NULL)
  51                 return NF_DROP;
  52
  53         /* rcu_read_lock()ed by nf_hook_thresh */
  54         helper = rcu_dereference(help->helper);
  55         if (helper == NULL)
  56                 return NF_DROP;
  57
  58         /* This is a user-space helper not yet configured, skip. */
  59         if ((helper->flags &
  60             (NF_CT_HELPER_F_USERSPACE | NF_CT_HELPER_F_CONFIGURED)) ==
  61              NF_CT_HELPER_F_USERSPACE)
  62                 return NF_ACCEPT;
  63
  64         /* If the user-space helper is not available, don't block traffic. */
  65         return NF_QUEUE_NR(helper->queue_num) | NF_VERDICT_FLAG_QUEUE_BYPASS;
  66 }
  67
  68 static const struct nla_policy nfnl_cthelper_tuple_pol[NFCTH_TUPLE_MAX+1] = {
  69         [NFCTH_TUPLE_L3PROTONUM] = { .type = NLA_U16, },
  70         [NFCTH_TUPLE_L4PROTONUM] = { .type = NLA_U8, },
  71 };
  72
  73 static int
  74 nfnl_cthelper_parse_tuple(struct nf_conntrack_tuple *tuple,
  75                           const struct nlattr *attr)
  76 {
  77         int err;
  78         struct nlattr *tb[NFCTH_TUPLE_MAX+1];
  79
  80         err = nla_parse_nested(tb, NFCTH_TUPLE_MAX, attr,
  81                                nfnl_cthelper_tuple_pol, NULL);
  82         if (err < 0)
  83                 return err;
  84
  85         if (!tb[NFCTH_TUPLE_L3PROTONUM] || !tb[NFCTH_TUPLE_L4PROTONUM])
  86                 return -EINVAL;
  87
  88         /* Not all fields are initialized so first zero the tuple */
  89         memset(tuple, 0, sizeof(struct nf_conntrack_tuple));
  90
  91         tuple->src.l3num = ntohs(nla_get_be16(tb[NFCTH_TUPLE_L3PROTONUM]));
  92         tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]);
  93
  94         return 0;
  95 }
  96
  97 static int
  98 nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
  99 {
 100         struct nf_conn_help *help = nfct_help(ct);
 101
 102         if (attr == NULL)
 103                 return -EINVAL;
 104
 105         if (help->helper->data_len == 0)
 106                 return -EINVAL;
 107
 108         memcpy(help->data, nla_data(attr), help->helper->data_len);
 109         return 0;
 110 }
 111
 112 static int
 113 nfnl_cthelper_to_nlattr(struct sk_buff *skb, const struct nf_conn *ct)
 114 {
 115         const struct nf_conn_help *help = nfct_help(ct);
 116
 117         if (help->helper->data_len &&
 118             nla_put(skb, CTA_HELP_INFO, help->helper->data_len, &help->data))
 119                 goto nla_put_failure;
 120
 121         return 0;
 122
 123 nla_put_failure:
 124         return -ENOSPC;
 125 }
 126
 127 static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = {
 128         [NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING,
 129                                 .len = NF_CT_HELPER_NAME_LEN-1 },
 130         [NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, },
 131         [NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, },
 132 };
 133
 134 static int
 135 nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy,
 136                             const struct nlattr *attr)
 137 {
 138         int err;
 139         struct nlattr *tb[NFCTH_POLICY_MAX+1];
 140
 141         err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr,
 142                                nfnl_cthelper_expect_pol, NULL);
 143         if (err < 0)
 144                 return err;
 145
 146         if (!tb[NFCTH_POLICY_NAME] ||
 147             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 148             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 149                 return -EINVAL;
 150
 151         strncpy(expect_policy->name,
 152                 nla_data(tb[NFCTH_POLICY_NAME]), NF_CT_HELPER_NAME_LEN);
 153         expect_policy->max_expected =
 154                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 155         expect_policy->timeout =
 156                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 157
 158         return 0;
 159 }
 160
 161 static const struct nla_policy
 162 nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
 163         [NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, },
 164 };
 165
 166 static int
 167 nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper,
 168                                   const struct nlattr *attr)
 169 {
 170         int i, ret;
 171         struct nf_conntrack_expect_policy *expect_policy;
 172         struct nlattr *tb[NFCTH_POLICY_SET_MAX+1];
 173         unsigned int class_max;
 174
 175         ret = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
 176                                nfnl_cthelper_expect_policy_set, NULL);
 177         if (ret < 0)
 178                 return ret;
 179
 180         if (!tb[NFCTH_POLICY_SET_NUM])
 181                 return -EINVAL;
 182
 183         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 184         if (class_max == 0)
 185                 return -EINVAL;
 186         if (class_max > NF_CT_MAX_EXPECT_CLASSES)
 187                 return -EOVERFLOW;
 188
 189         expect_policy = kzalloc(sizeof(struct nf_conntrack_expect_policy) *
 190                                 class_max, GFP_KERNEL);
 191         if (expect_policy == NULL)
 192                 return -ENOMEM;
 193
 194         for (i = 0; i < class_max; i++) {
 195                 if (!tb[NFCTH_POLICY_SET+i])
 196                         goto err;
 197
 198                 ret = nfnl_cthelper_expect_policy(&expect_policy[i],
 199                                                   tb[NFCTH_POLICY_SET+i]);
 200                 if (ret < 0)
 201                         goto err;
 202         }
 203
 204         helper->expect_class_max = class_max - 1;
 205         helper->expect_policy = expect_policy;
 206         return 0;
 207 err:
 208         kfree(expect_policy);
 209         return -EINVAL;
 210 }
 211
 212 static int
 213 nfnl_cthelper_create(const struct nlattr * const tb[],
 214                      struct nf_conntrack_tuple *tuple)
 215 {
 216         struct nf_conntrack_helper *helper;
 217         struct nfnl_cthelper *nfcth;
 218         int ret;
 219
 220         if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
 221                 return -EINVAL;
 222
 223         nfcth = kzalloc(sizeof(*nfcth), GFP_KERNEL);
 224         if (nfcth == NULL)
 225                 return -ENOMEM;
 226         helper = &nfcth->helper;
 227
 228         ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
 229         if (ret < 0)
 230                 goto err1;
 231
 232         strncpy(helper->name, nla_data(tb[NFCTH_NAME]), NF_CT_HELPER_NAME_LEN);
 233         helper->data_len = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
 234         helper->flags |= NF_CT_HELPER_F_USERSPACE;
 235         memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
 236
 237         helper->me = THIS_MODULE;
 238         helper->help = nfnl_userspace_cthelper;
 239         helper->from_nlattr = nfnl_cthelper_from_nlattr;
 240         helper->to_nlattr = nfnl_cthelper_to_nlattr;
 241
 242         /* Default to queue number zero, this can be updated at any time. */
 243         if (tb[NFCTH_QUEUE_NUM])
 244                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 245
 246         if (tb[NFCTH_STATUS]) {
 247                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 248
 249                 switch(status) {
 250                 case NFCT_HELPER_STATUS_ENABLED:
 251                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 252                         break;
 253                 case NFCT_HELPER_STATUS_DISABLED:
 254                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 255                         break;
 256                 }
 257         }
 258
 259         ret = nf_conntrack_helper_register(helper);
 260         if (ret < 0)
 261                 goto err2;
 262
 263         list_add_tail(&nfcth->list, &nfnl_cthelper_list);
 264         return 0;
 265 err2:
 266         kfree(helper->expect_policy);
 267 err1:
 268         kfree(nfcth);
 269         return ret;
 270 }
 271
 272 static int
 273 nfnl_cthelper_update_policy_one(const struct nf_conntrack_expect_policy *policy,
 274                                 struct nf_conntrack_expect_policy *new_policy,
 275                                 const struct nlattr *attr)
 276 {
 277         struct nlattr *tb[NFCTH_POLICY_MAX + 1];
 278         int err;
 279
 280         err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr,
 281                                nfnl_cthelper_expect_pol, NULL);
 282         if (err < 0)
 283                 return err;
 284
 285         if (!tb[NFCTH_POLICY_NAME] ||
 286             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 287             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 288                 return -EINVAL;
 289
 290         if (nla_strcmp(tb[NFCTH_POLICY_NAME], policy->name))
 291                 return -EBUSY;
 292
 293         new_policy->max_expected =
 294                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 295         new_policy->timeout =
 296                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 297
 298         return 0;
 299 }
 300
 301 static int nfnl_cthelper_update_policy_all(struct nlattr *tb[],
 302                                            struct nf_conntrack_helper *helper)
 303 {
 304         struct nf_conntrack_expect_policy new_policy[helper->expect_class_max + 1];
 305         struct nf_conntrack_expect_policy *policy;
 306         int i, err;
 307
 308         /* Check first that all policy attributes are well-formed, so we don't
 309          * leave things in inconsistent state on errors.
 310          */
 311         for (i = 0; i < helper->expect_class_max + 1; i++) {
 312
 313                 if (!tb[NFCTH_POLICY_SET + i])
 314                         return -EINVAL;
 315
 316                 err = nfnl_cthelper_update_policy_one(&helper->expect_policy[i],
 317                                                       &new_policy[i],
 318                                                       tb[NFCTH_POLICY_SET + i]);
 319                 if (err < 0)
 320                         return err;
 321         }
 322         /* Now we can safely update them. */
 323         for (i = 0; i < helper->expect_class_max + 1; i++) {
 324                 policy = (struct nf_conntrack_expect_policy *)
 325                                 &helper->expect_policy[i];
 326                 policy->max_expected = new_policy->max_expected;
 327                 policy->timeout = new_policy->timeout;
 328         }
 329
 330         return 0;
 331 }
 332
 333 static int nfnl_cthelper_update_policy(struct nf_conntrack_helper *helper,
 334                                        const struct nlattr *attr)
 335 {
 336         struct nlattr *tb[NFCTH_POLICY_SET_MAX + 1];
 337         unsigned int class_max;
 338         int err;
 339
 340         err = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
 341                                nfnl_cthelper_expect_policy_set, NULL);
 342         if (err < 0)
 343                 return err;
 344
 345         if (!tb[NFCTH_POLICY_SET_NUM])
 346                 return -EINVAL;
 347
 348         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 349         if (helper->expect_class_max + 1 != class_max)
 350                 return -EBUSY;
 351
 352         return nfnl_cthelper_update_policy_all(tb, helper);
 353 }
 354
 355 static int
 356 nfnl_cthelper_update(const struct nlattr * const tb[],
 357                      struct nf_conntrack_helper *helper)
 358 {
 359         int ret;
 360
 361         if (tb[NFCTH_PRIV_DATA_LEN])
 362                 return -EBUSY;
 363
 364         if (tb[NFCTH_POLICY]) {
 365                 ret = nfnl_cthelper_update_policy(helper, tb[NFCTH_POLICY]);
 366                 if (ret < 0)
 367                         return ret;
 368         }
 369         if (tb[NFCTH_QUEUE_NUM])
 370                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 371
 372         if (tb[NFCTH_STATUS]) {
 373                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 374
 375                 switch(status) {
 376                 case NFCT_HELPER_STATUS_ENABLED:
 377                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 378                         break;
 379                 case NFCT_HELPER_STATUS_DISABLED:
 380                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 381                         break;
 382                 }
 383         }
 384         return 0;
 385 }
 386
 387 static int nfnl_cthelper_new(struct net *net, struct sock *nfnl,
 388                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 389                              const struct nlattr * const tb[])
 390 {
 391         const char *helper_name;
 392         struct nf_conntrack_helper *cur, *helper = NULL;
 393         struct nf_conntrack_tuple tuple;
 394         struct nfnl_cthelper *nlcth;
 395         int ret = 0;
 396
 397         if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
 398                 return -EINVAL;
 399
 400         helper_name = nla_data(tb[NFCTH_NAME]);
 401
 402         ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 403         if (ret < 0)
 404                 return ret;
 405
 406         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 407                 cur = &nlcth->helper;
 408
 409                 if (strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 410                         continue;
 411
 412                 if ((tuple.src.l3num != cur->tuple.src.l3num ||
 413                      tuple.dst.protonum != cur->tuple.dst.protonum))
 414                         continue;
 415
 416                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 417                         return -EEXIST;
 418
 419                 helper = cur;
 420                 break;
 421         }
 422
 423         if (helper == NULL)
 424                 ret = nfnl_cthelper_create(tb, &tuple);
 425         else
 426                 ret = nfnl_cthelper_update(tb, helper);
 427
 428         return ret;
 429 }
 430
 431 static int
 432 nfnl_cthelper_dump_tuple(struct sk_buff *skb,
 433                          struct nf_conntrack_helper *helper)
 434 {
 435         struct nlattr *nest_parms;
 436
 437         nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
 438         if (nest_parms == NULL)
 439                 goto nla_put_failure;
 440
 441         if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
 442                          htons(helper->tuple.src.l3num)))
 443                 goto nla_put_failure;
 444
 445         if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
 446                 goto nla_put_failure;
 447
 448         nla_nest_end(skb, nest_parms);
 449         return 0;
 450
 451 nla_put_failure:
 452         return -1;
 453 }
 454
 455 static int
 456 nfnl_cthelper_dump_policy(struct sk_buff *skb,
 457                         struct nf_conntrack_helper *helper)
 458 {
 459         int i;
 460         struct nlattr *nest_parms1, *nest_parms2;
 461
 462         nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
 463         if (nest_parms1 == NULL)
 464                 goto nla_put_failure;
 465
 466         if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
 467                          htonl(helper->expect_class_max + 1)))
 468                 goto nla_put_failure;
 469
 470         for (i = 0; i < helper->expect_class_max + 1; i++) {
 471                 nest_parms2 = nla_nest_start(skb,
 472                                 (NFCTH_POLICY_SET+i) | NLA_F_NESTED);
 473                 if (nest_parms2 == NULL)
 474                         goto nla_put_failure;
 475
 476                 if (nla_put_string(skb, NFCTH_POLICY_NAME,
 477                                    helper->expect_policy[i].name))
 478                         goto nla_put_failure;
 479
 480                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
 481                                  htonl(helper->expect_policy[i].max_expected)))
 482                         goto nla_put_failure;
 483
 484                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
 485                                  htonl(helper->expect_policy[i].timeout)))
 486                         goto nla_put_failure;
 487
 488                 nla_nest_end(skb, nest_parms2);
 489         }
 490         nla_nest_end(skb, nest_parms1);
 491         return 0;
 492
 493 nla_put_failure:
 494         return -1;
 495 }
 496
 497 static int
 498 nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 499                         int event, struct nf_conntrack_helper *helper)
 500 {
 501         struct nlmsghdr *nlh;
 502         struct nfgenmsg *nfmsg;
 503         unsigned int flags = portid ? NLM_F_MULTI : 0;
 504         int status;
 505
 506         event |= NFNL_SUBSYS_CTHELPER << 8;
 507         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 508         if (nlh == NULL)
 509                 goto nlmsg_failure;
 510
 511         nfmsg = nlmsg_data(nlh);
 512         nfmsg->nfgen_family = AF_UNSPEC;
 513         nfmsg->version = NFNETLINK_V0;
 514         nfmsg->res_id = 0;
 515
 516         if (nla_put_string(skb, NFCTH_NAME, helper->name))
 517                 goto nla_put_failure;
 518
 519         if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
 520                 goto nla_put_failure;
 521
 522         if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
 523                 goto nla_put_failure;
 524
 525         if (nfnl_cthelper_dump_policy(skb, helper) < 0)
 526                 goto nla_put_failure;
 527
 528         if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
 529                 goto nla_put_failure;
 530
 531         if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
 532                 status = NFCT_HELPER_STATUS_ENABLED;
 533         else
 534                 status = NFCT_HELPER_STATUS_DISABLED;
 535
 536         if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
 537                 goto nla_put_failure;
 538
 539         nlmsg_end(skb, nlh);
 540         return skb->len;
 541
 542 nlmsg_failure:
 543 nla_put_failure:
 544         nlmsg_cancel(skb, nlh);
 545         return -1;
 546 }
 547
 548 static int
 549 nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
 550 {
 551         struct nf_conntrack_helper *cur, *last;
 552
 553         rcu_read_lock();
 554         last = (struct nf_conntrack_helper *)cb->args[1];
 555         for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
 556 restart:
 557                 hlist_for_each_entry_rcu(cur,
 558                                 &nf_ct_helper_hash[cb->args[0]], hnode) {
 559
 560                         /* skip non-userspace conntrack helpers. */
 561                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 562                                 continue;
 563
 564                         if (cb->args[1]) {
 565                                 if (cur != last)
 566                                         continue;
 567                                 cb->args[1] = 0;
 568                         }
 569                         if (nfnl_cthelper_fill_info(skb,
 570                                             NETLINK_CB(cb->skb).portid,
 571                                             cb->nlh->nlmsg_seq,
 572                                             NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 573                                             NFNL_MSG_CTHELPER_NEW, cur) < 0) {
 574                                 cb->args[1] = (unsigned long)cur;
 575                                 goto out;
 576                         }
 577                 }
 578         }
 579         if (cb->args[1]) {
 580                 cb->args[1] = 0;
 581                 goto restart;
 582         }
 583 out:
 584         rcu_read_unlock();
 585         return skb->len;
 586 }
 587
 588 static int nfnl_cthelper_get(struct net *net, struct sock *nfnl,
 589                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 590                              const struct nlattr * const tb[])
 591 {
 592         int ret = -ENOENT;
 593         struct nf_conntrack_helper *cur;
 594         struct sk_buff *skb2;
 595         char *helper_name = NULL;
 596         struct nf_conntrack_tuple tuple;
 597         struct nfnl_cthelper *nlcth;
 598         bool tuple_set = false;
 599
 600         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 601                 struct netlink_dump_control c = {
 602                         .dump = nfnl_cthelper_dump_table,
 603                 };
 604                 return netlink_dump_start(nfnl, skb, nlh, &c);
 605         }
 606
 607         if (tb[NFCTH_NAME])
 608                 helper_name = nla_data(tb[NFCTH_NAME]);
 609
 610         if (tb[NFCTH_TUPLE]) {
 611                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 612                 if (ret < 0)
 613                         return ret;
 614
 615                 tuple_set = true;
 616         }
 617
 618         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 619                 cur = &nlcth->helper;
 620                 if (helper_name &&
 621                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 622                         continue;
 623
 624                 if (tuple_set &&
 625                     (tuple.src.l3num != cur->tuple.src.l3num ||
 626                      tuple.dst.protonum != cur->tuple.dst.protonum))
 627                         continue;
 628
 629                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 630                 if (skb2 == NULL) {
 631                         ret = -ENOMEM;
 632                         break;
 633                 }
 634
 635                 ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
 636                                               nlh->nlmsg_seq,
 637                                               NFNL_MSG_TYPE(nlh->nlmsg_type),
 638                                               NFNL_MSG_CTHELPER_NEW, cur);
 639                 if (ret <= 0) {
 640                         kfree_skb(skb2);
 641                         break;
 642                 }
 643
 644                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 645                                       MSG_DONTWAIT);
 646                 if (ret > 0)
 647                         ret = 0;
 648
 649                 /* this avoids a loop in nfnetlink. */
 650                 return ret == -EAGAIN ? -ENOBUFS : ret;
 651         }
 652         return ret;
 653 }
 654
 655 static int nfnl_cthelper_del(struct net *net, struct sock *nfnl,
 656                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 657                              const struct nlattr * const tb[])
 658 {
 659         char *helper_name = NULL;
 660         struct nf_conntrack_helper *cur;
 661         struct nf_conntrack_tuple tuple;
 662         bool tuple_set = false, found = false;
 663         struct nfnl_cthelper *nlcth, *n;
 664         int j = 0, ret;
 665
 666         if (tb[NFCTH_NAME])
 667                 helper_name = nla_data(tb[NFCTH_NAME]);
 668
 669         if (tb[NFCTH_TUPLE]) {
 670                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 671                 if (ret < 0)
 672                         return ret;
 673
 674                 tuple_set = true;
 675         }
 676
 677         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 678                 cur = &nlcth->helper;
 679                 j++;
 680
 681                 if (helper_name &&
 682                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 683                         continue;
 684
 685                 if (tuple_set &&
 686                     (tuple.src.l3num != cur->tuple.src.l3num ||
 687                      tuple.dst.protonum != cur->tuple.dst.protonum))
 688                         continue;
 689
 690                 found = true;
 691                 nf_conntrack_helper_unregister(cur);
 692                 kfree(cur->expect_policy);
 693
 694                 list_del(&nlcth->list);
 695                 kfree(nlcth);
 696         }
 697
 698         /* Make sure we return success if we flush and there is no helpers */
 699         return (found || j == 0) ? 0 : -ENOENT;
 700 }
 701
 702 static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
 703         [NFCTH_NAME] = { .type = NLA_NUL_STRING,
 704                          .len = NF_CT_HELPER_NAME_LEN-1 },
 705         [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
 706 };
 707
 708 static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
 709         [NFNL_MSG_CTHELPER_NEW]         = { .call = nfnl_cthelper_new,
 710                                             .attr_count = NFCTH_MAX,
 711                                             .policy = nfnl_cthelper_policy },
 712         [NFNL_MSG_CTHELPER_GET]         = { .call = nfnl_cthelper_get,
 713                                             .attr_count = NFCTH_MAX,
 714                                             .policy = nfnl_cthelper_policy },
 715         [NFNL_MSG_CTHELPER_DEL]         = { .call = nfnl_cthelper_del,
 716                                             .attr_count = NFCTH_MAX,
 717                                             .policy = nfnl_cthelper_policy },
 718 };
 719
 720 static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
 721         .name                           = "cthelper",
 722         .subsys_id                      = NFNL_SUBSYS_CTHELPER,
 723         .cb_count                       = NFNL_MSG_CTHELPER_MAX,
 724         .cb                             = nfnl_cthelper_cb,
 725 };
 726
 727 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
 728
 729 static int __init nfnl_cthelper_init(void)
 730 {
 731         int ret;
 732
 733         ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
 734         if (ret < 0) {
 735                 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
 736                 goto err_out;
 737         }
 738         return 0;
 739 err_out:
 740         return ret;
 741 }
 742
 743 static void __exit nfnl_cthelper_exit(void)
 744 {
 745         struct nf_conntrack_helper *cur;
 746         struct nfnl_cthelper *nlcth, *n;
 747
 748         nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
 749
 750         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 751                 cur = &nlcth->helper;
 752
 753                 nf_conntrack_helper_unregister(cur);
 754                 kfree(cur->expect_policy);
 755                 kfree(nlcth);
 756         }
 757 }
 758
 759 module_init(nfnl_cthelper_init);
 760 module_exit(nfnl_cthelper_exit);