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, nfnl_cthelper_tuple_pol);
  81         if (err < 0)
  82                 return err;
  83
  84         if (!tb[NFCTH_TUPLE_L3PROTONUM] || !tb[NFCTH_TUPLE_L4PROTONUM])
  85                 return -EINVAL;
  86
  87         /* Not all fields are initialized so first zero the tuple */
  88         memset(tuple, 0, sizeof(struct nf_conntrack_tuple));
  89
  90         tuple->src.l3num = ntohs(nla_get_be16(tb[NFCTH_TUPLE_L3PROTONUM]));
  91         tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]);
  92
  93         return 0;
  94 }
  95
  96 static int
  97 nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
  98 {
  99         struct nf_conn_help *help = nfct_help(ct);
 100
 101         if (attr == NULL)
 102                 return -EINVAL;
 103
 104         if (help->helper->data_len == 0)
 105                 return -EINVAL;
 106
 107         nla_memcpy(help->data, nla_data(attr), sizeof(help->data));
 108         return 0;
 109 }
 110
 111 static int
 112 nfnl_cthelper_to_nlattr(struct sk_buff *skb, const struct nf_conn *ct)
 113 {
 114         const struct nf_conn_help *help = nfct_help(ct);
 115
 116         if (help->helper->data_len &&
 117             nla_put(skb, CTA_HELP_INFO, help->helper->data_len, &help->data))
 118                 goto nla_put_failure;
 119
 120         return 0;
 121
 122 nla_put_failure:
 123         return -ENOSPC;
 124 }
 125
 126 static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = {
 127         [NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING,
 128                                 .len = NF_CT_HELPER_NAME_LEN-1 },
 129         [NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, },
 130         [NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, },
 131 };
 132
 133 static int
 134 nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy,
 135                             const struct nlattr *attr)
 136 {
 137         int err;
 138         struct nlattr *tb[NFCTH_POLICY_MAX+1];
 139
 140         err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr, nfnl_cthelper_expect_pol);
 141         if (err < 0)
 142                 return err;
 143
 144         if (!tb[NFCTH_POLICY_NAME] ||
 145             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 146             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 147                 return -EINVAL;
 148
 149         strncpy(expect_policy->name,
 150                 nla_data(tb[NFCTH_POLICY_NAME]), NF_CT_HELPER_NAME_LEN);
 151         expect_policy->max_expected =
 152                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 153         if (expect_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
 154                 return -EINVAL;
 155
 156         expect_policy->timeout =
 157                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 158
 159         return 0;
 160 }
 161
 162 static const struct nla_policy
 163 nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
 164         [NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, },
 165 };
 166
 167 static int
 168 nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper,
 169                                   const struct nlattr *attr)
 170 {
 171         int i, ret;
 172         struct nf_conntrack_expect_policy *expect_policy;
 173         struct nlattr *tb[NFCTH_POLICY_SET_MAX+1];
 174         unsigned int class_max;
 175
 176         ret = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
 177                                nfnl_cthelper_expect_policy_set);
 178         if (ret < 0)
 179                 return ret;
 180
 181         if (!tb[NFCTH_POLICY_SET_NUM])
 182                 return -EINVAL;
 183
 184         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 185         if (class_max == 0)
 186                 return -EINVAL;
 187         if (class_max > NF_CT_MAX_EXPECT_CLASSES)
 188                 return -EOVERFLOW;
 189
 190         expect_policy = kzalloc(sizeof(struct nf_conntrack_expect_policy) *
 191                                 class_max, GFP_KERNEL);
 192         if (expect_policy == NULL)
 193                 return -ENOMEM;
 194
 195         for (i = 0; i < class_max; i++) {
 196                 if (!tb[NFCTH_POLICY_SET+i])
 197                         goto err;
 198
 199                 ret = nfnl_cthelper_expect_policy(&expect_policy[i],
 200                                                   tb[NFCTH_POLICY_SET+i]);
 201                 if (ret < 0)
 202                         goto err;
 203         }
 204
 205         helper->expect_class_max = class_max - 1;
 206         helper->expect_policy = expect_policy;
 207         return 0;
 208 err:
 209         kfree(expect_policy);
 210         return -EINVAL;
 211 }
 212
 213 static int
 214 nfnl_cthelper_create(const struct nlattr * const tb[],
 215                      struct nf_conntrack_tuple *tuple)
 216 {
 217         struct nf_conntrack_helper *helper;
 218         struct nfnl_cthelper *nfcth;
 219         unsigned int size;
 220         int ret;
 221
 222         if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
 223                 return -EINVAL;
 224
 225         nfcth = kzalloc(sizeof(*nfcth), GFP_KERNEL);
 226         if (nfcth == NULL)
 227                 return -ENOMEM;
 228         helper = &nfcth->helper;
 229
 230         ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
 231         if (ret < 0)
 232                 goto err1;
 233
 234         strncpy(helper->name, nla_data(tb[NFCTH_NAME]), NF_CT_HELPER_NAME_LEN);
 235         size = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
 236         if (size > FIELD_SIZEOF(struct nf_conn_help, data)) {
 237                 ret = -ENOMEM;
 238                 goto err2;
 239         }
 240
 241         helper->flags |= NF_CT_HELPER_F_USERSPACE;
 242         memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
 243
 244         helper->me = THIS_MODULE;
 245         helper->help = nfnl_userspace_cthelper;
 246         helper->from_nlattr = nfnl_cthelper_from_nlattr;
 247         helper->to_nlattr = nfnl_cthelper_to_nlattr;
 248
 249         /* Default to queue number zero, this can be updated at any time. */
 250         if (tb[NFCTH_QUEUE_NUM])
 251                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 252
 253         if (tb[NFCTH_STATUS]) {
 254                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 255
 256                 switch(status) {
 257                 case NFCT_HELPER_STATUS_ENABLED:
 258                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 259                         break;
 260                 case NFCT_HELPER_STATUS_DISABLED:
 261                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 262                         break;
 263                 }
 264         }
 265
 266         ret = nf_conntrack_helper_register(helper);
 267         if (ret < 0)
 268                 goto err2;
 269
 270         list_add_tail(&nfcth->list, &nfnl_cthelper_list);
 271         return 0;
 272 err2:
 273         kfree(helper->expect_policy);
 274 err1:
 275         kfree(nfcth);
 276         return ret;
 277 }
 278
 279 static int
 280 nfnl_cthelper_update_policy_one(const struct nf_conntrack_expect_policy *policy,
 281                                 struct nf_conntrack_expect_policy *new_policy,
 282                                 const struct nlattr *attr)
 283 {
 284         struct nlattr *tb[NFCTH_POLICY_MAX + 1];
 285         int err;
 286
 287         err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr,
 288                                nfnl_cthelper_expect_pol);
 289         if (err < 0)
 290                 return err;
 291
 292         if (!tb[NFCTH_POLICY_NAME] ||
 293             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 294             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 295                 return -EINVAL;
 296
 297         if (nla_strcmp(tb[NFCTH_POLICY_NAME], policy->name))
 298                 return -EBUSY;
 299
 300         new_policy->max_expected =
 301                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 302         if (new_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
 303                 return -EINVAL;
 304
 305         new_policy->timeout =
 306                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 307
 308         return 0;
 309 }
 310
 311 static int nfnl_cthelper_update_policy_all(struct nlattr *tb[],
 312                                            struct nf_conntrack_helper *helper)
 313 {
 314         struct nf_conntrack_expect_policy new_policy[helper->expect_class_max + 1];
 315         struct nf_conntrack_expect_policy *policy;
 316         int i, err;
 317
 318         /* Check first that all policy attributes are well-formed, so we don't
 319          * leave things in inconsistent state on errors.
 320          */
 321         for (i = 0; i < helper->expect_class_max + 1; i++) {
 322
 323                 if (!tb[NFCTH_POLICY_SET + i])
 324                         return -EINVAL;
 325
 326                 err = nfnl_cthelper_update_policy_one(&helper->expect_policy[i],
 327                                                       &new_policy[i],
 328                                                       tb[NFCTH_POLICY_SET + i]);
 329                 if (err < 0)
 330                         return err;
 331         }
 332         /* Now we can safely update them. */
 333         for (i = 0; i < helper->expect_class_max + 1; i++) {
 334                 policy = (struct nf_conntrack_expect_policy *)
 335                                 &helper->expect_policy[i];
 336                 policy->max_expected = new_policy->max_expected;
 337                 policy->timeout = new_policy->timeout;
 338         }
 339
 340         return 0;
 341 }
 342
 343 static int nfnl_cthelper_update_policy(struct nf_conntrack_helper *helper,
 344                                        const struct nlattr *attr)
 345 {
 346         struct nlattr *tb[NFCTH_POLICY_SET_MAX + 1];
 347         unsigned int class_max;
 348         int err;
 349
 350         err = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
 351                                nfnl_cthelper_expect_policy_set);
 352         if (err < 0)
 353                 return err;
 354
 355         if (!tb[NFCTH_POLICY_SET_NUM])
 356                 return -EINVAL;
 357
 358         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 359         if (helper->expect_class_max + 1 != class_max)
 360                 return -EBUSY;
 361
 362         return nfnl_cthelper_update_policy_all(tb, helper);
 363 }
 364
 365 static int
 366 nfnl_cthelper_update(const struct nlattr * const tb[],
 367                      struct nf_conntrack_helper *helper)
 368 {
 369         int ret;
 370
 371         if (tb[NFCTH_PRIV_DATA_LEN])
 372                 return -EBUSY;
 373
 374         if (tb[NFCTH_POLICY]) {
 375                 ret = nfnl_cthelper_update_policy(helper, tb[NFCTH_POLICY]);
 376                 if (ret < 0)
 377                         return ret;
 378         }
 379         if (tb[NFCTH_QUEUE_NUM])
 380                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 381
 382         if (tb[NFCTH_STATUS]) {
 383                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 384
 385                 switch(status) {
 386                 case NFCT_HELPER_STATUS_ENABLED:
 387                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 388                         break;
 389                 case NFCT_HELPER_STATUS_DISABLED:
 390                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 391                         break;
 392                 }
 393         }
 394         return 0;
 395 }
 396
 397 static int nfnl_cthelper_new(struct net *net, struct sock *nfnl,
 398                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 399                              const struct nlattr * const tb[])
 400 {
 401         const char *helper_name;
 402         struct nf_conntrack_helper *cur, *helper = NULL;
 403         struct nf_conntrack_tuple tuple;
 404         struct nfnl_cthelper *nlcth;
 405         int ret = 0;
 406
 407         if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
 408                 return -EINVAL;
 409
 410         helper_name = nla_data(tb[NFCTH_NAME]);
 411
 412         ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 413         if (ret < 0)
 414                 return ret;
 415
 416         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 417                 cur = &nlcth->helper;
 418
 419                 if (strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 420                         continue;
 421
 422                 if ((tuple.src.l3num != cur->tuple.src.l3num ||
 423                      tuple.dst.protonum != cur->tuple.dst.protonum))
 424                         continue;
 425
 426                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 427                         return -EEXIST;
 428
 429                 helper = cur;
 430                 break;
 431         }
 432
 433         if (helper == NULL)
 434                 ret = nfnl_cthelper_create(tb, &tuple);
 435         else
 436                 ret = nfnl_cthelper_update(tb, helper);
 437
 438         return ret;
 439 }
 440
 441 static int
 442 nfnl_cthelper_dump_tuple(struct sk_buff *skb,
 443                          struct nf_conntrack_helper *helper)
 444 {
 445         struct nlattr *nest_parms;
 446
 447         nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
 448         if (nest_parms == NULL)
 449                 goto nla_put_failure;
 450
 451         if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
 452                          htons(helper->tuple.src.l3num)))
 453                 goto nla_put_failure;
 454
 455         if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
 456                 goto nla_put_failure;
 457
 458         nla_nest_end(skb, nest_parms);
 459         return 0;
 460
 461 nla_put_failure:
 462         return -1;
 463 }
 464
 465 static int
 466 nfnl_cthelper_dump_policy(struct sk_buff *skb,
 467                         struct nf_conntrack_helper *helper)
 468 {
 469         int i;
 470         struct nlattr *nest_parms1, *nest_parms2;
 471
 472         nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
 473         if (nest_parms1 == NULL)
 474                 goto nla_put_failure;
 475
 476         if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
 477                          htonl(helper->expect_class_max + 1)))
 478                 goto nla_put_failure;
 479
 480         for (i = 0; i < helper->expect_class_max + 1; i++) {
 481                 nest_parms2 = nla_nest_start(skb,
 482                                 (NFCTH_POLICY_SET+i) | NLA_F_NESTED);
 483                 if (nest_parms2 == NULL)
 484                         goto nla_put_failure;
 485
 486                 if (nla_put_string(skb, NFCTH_POLICY_NAME,
 487                                    helper->expect_policy[i].name))
 488                         goto nla_put_failure;
 489
 490                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
 491                                  htonl(helper->expect_policy[i].max_expected)))
 492                         goto nla_put_failure;
 493
 494                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
 495                                  htonl(helper->expect_policy[i].timeout)))
 496                         goto nla_put_failure;
 497
 498                 nla_nest_end(skb, nest_parms2);
 499         }
 500         nla_nest_end(skb, nest_parms1);
 501         return 0;
 502
 503 nla_put_failure:
 504         return -1;
 505 }
 506
 507 static int
 508 nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 509                         int event, struct nf_conntrack_helper *helper)
 510 {
 511         struct nlmsghdr *nlh;
 512         struct nfgenmsg *nfmsg;
 513         unsigned int flags = portid ? NLM_F_MULTI : 0;
 514         int status;
 515
 516         event = nfnl_msg_type(NFNL_SUBSYS_CTHELPER, event);
 517         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 518         if (nlh == NULL)
 519                 goto nlmsg_failure;
 520
 521         nfmsg = nlmsg_data(nlh);
 522         nfmsg->nfgen_family = AF_UNSPEC;
 523         nfmsg->version = NFNETLINK_V0;
 524         nfmsg->res_id = 0;
 525
 526         if (nla_put_string(skb, NFCTH_NAME, helper->name))
 527                 goto nla_put_failure;
 528
 529         if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
 530                 goto nla_put_failure;
 531
 532         if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
 533                 goto nla_put_failure;
 534
 535         if (nfnl_cthelper_dump_policy(skb, helper) < 0)
 536                 goto nla_put_failure;
 537
 538         if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
 539                 goto nla_put_failure;
 540
 541         if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
 542                 status = NFCT_HELPER_STATUS_ENABLED;
 543         else
 544                 status = NFCT_HELPER_STATUS_DISABLED;
 545
 546         if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
 547                 goto nla_put_failure;
 548
 549         nlmsg_end(skb, nlh);
 550         return skb->len;
 551
 552 nlmsg_failure:
 553 nla_put_failure:
 554         nlmsg_cancel(skb, nlh);
 555         return -1;
 556 }
 557
 558 static int
 559 nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
 560 {
 561         struct nf_conntrack_helper *cur, *last;
 562
 563         rcu_read_lock();
 564         last = (struct nf_conntrack_helper *)cb->args[1];
 565         for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
 566 restart:
 567                 hlist_for_each_entry_rcu(cur,
 568                                 &nf_ct_helper_hash[cb->args[0]], hnode) {
 569
 570                         /* skip non-userspace conntrack helpers. */
 571                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 572                                 continue;
 573
 574                         if (cb->args[1]) {
 575                                 if (cur != last)
 576                                         continue;
 577                                 cb->args[1] = 0;
 578                         }
 579                         if (nfnl_cthelper_fill_info(skb,
 580                                             NETLINK_CB(cb->skb).portid,
 581                                             cb->nlh->nlmsg_seq,
 582                                             NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 583                                             NFNL_MSG_CTHELPER_NEW, cur) < 0) {
 584                                 cb->args[1] = (unsigned long)cur;
 585                                 goto out;
 586                         }
 587                 }
 588         }
 589         if (cb->args[1]) {
 590                 cb->args[1] = 0;
 591                 goto restart;
 592         }
 593 out:
 594         rcu_read_unlock();
 595         return skb->len;
 596 }
 597
 598 static int nfnl_cthelper_get(struct net *net, struct sock *nfnl,
 599                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 600                              const struct nlattr * const tb[])
 601 {
 602         int ret = -ENOENT;
 603         struct nf_conntrack_helper *cur;
 604         struct sk_buff *skb2;
 605         char *helper_name = NULL;
 606         struct nf_conntrack_tuple tuple;
 607         struct nfnl_cthelper *nlcth;
 608         bool tuple_set = false;
 609
 610         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 611                 struct netlink_dump_control c = {
 612                         .dump = nfnl_cthelper_dump_table,
 613                 };
 614                 return netlink_dump_start(nfnl, skb, nlh, &c);
 615         }
 616
 617         if (tb[NFCTH_NAME])
 618                 helper_name = nla_data(tb[NFCTH_NAME]);
 619
 620         if (tb[NFCTH_TUPLE]) {
 621                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 622                 if (ret < 0)
 623                         return ret;
 624
 625                 tuple_set = true;
 626         }
 627
 628         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 629                 cur = &nlcth->helper;
 630                 if (helper_name &&
 631                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 632                         continue;
 633
 634                 if (tuple_set &&
 635                     (tuple.src.l3num != cur->tuple.src.l3num ||
 636                      tuple.dst.protonum != cur->tuple.dst.protonum))
 637                         continue;
 638
 639                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 640                 if (skb2 == NULL) {
 641                         ret = -ENOMEM;
 642                         break;
 643                 }
 644
 645                 ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
 646                                               nlh->nlmsg_seq,
 647                                               NFNL_MSG_TYPE(nlh->nlmsg_type),
 648                                               NFNL_MSG_CTHELPER_NEW, cur);
 649                 if (ret <= 0) {
 650                         kfree_skb(skb2);
 651                         break;
 652                 }
 653
 654                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 655                                       MSG_DONTWAIT);
 656                 if (ret > 0)
 657                         ret = 0;
 658
 659                 /* this avoids a loop in nfnetlink. */
 660                 return ret == -EAGAIN ? -ENOBUFS : ret;
 661         }
 662         return ret;
 663 }
 664
 665 static int nfnl_cthelper_del(struct net *net, struct sock *nfnl,
 666                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 667                              const struct nlattr * const tb[])
 668 {
 669         char *helper_name = NULL;
 670         struct nf_conntrack_helper *cur;
 671         struct nf_conntrack_tuple tuple;
 672         bool tuple_set = false, found = false;
 673         struct nfnl_cthelper *nlcth, *n;
 674         int j = 0, ret;
 675
 676         if (tb[NFCTH_NAME])
 677                 helper_name = nla_data(tb[NFCTH_NAME]);
 678
 679         if (tb[NFCTH_TUPLE]) {
 680                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 681                 if (ret < 0)
 682                         return ret;
 683
 684                 tuple_set = true;
 685         }
 686
 687         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 688                 cur = &nlcth->helper;
 689                 j++;
 690
 691                 if (helper_name &&
 692                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 693                         continue;
 694
 695                 if (tuple_set &&
 696                     (tuple.src.l3num != cur->tuple.src.l3num ||
 697                      tuple.dst.protonum != cur->tuple.dst.protonum))
 698                         continue;
 699
 700                 found = true;
 701                 nf_conntrack_helper_unregister(cur);
 702                 kfree(cur->expect_policy);
 703
 704                 list_del(&nlcth->list);
 705                 kfree(nlcth);
 706         }
 707
 708         /* Make sure we return success if we flush and there is no helpers */
 709         return (found || j == 0) ? 0 : -ENOENT;
 710 }
 711
 712 static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
 713         [NFCTH_NAME] = { .type = NLA_NUL_STRING,
 714                          .len = NF_CT_HELPER_NAME_LEN-1 },
 715         [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
 716 };
 717
 718 static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
 719         [NFNL_MSG_CTHELPER_NEW]         = { .call = nfnl_cthelper_new,
 720                                             .attr_count = NFCTH_MAX,
 721                                             .policy = nfnl_cthelper_policy },
 722         [NFNL_MSG_CTHELPER_GET]         = { .call = nfnl_cthelper_get,
 723                                             .attr_count = NFCTH_MAX,
 724                                             .policy = nfnl_cthelper_policy },
 725         [NFNL_MSG_CTHELPER_DEL]         = { .call = nfnl_cthelper_del,
 726                                             .attr_count = NFCTH_MAX,
 727                                             .policy = nfnl_cthelper_policy },
 728 };
 729
 730 static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
 731         .name                           = "cthelper",
 732         .subsys_id                      = NFNL_SUBSYS_CTHELPER,
 733         .cb_count                       = NFNL_MSG_CTHELPER_MAX,
 734         .cb                             = nfnl_cthelper_cb,
 735 };
 736
 737 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
 738
 739 static int __init nfnl_cthelper_init(void)
 740 {
 741         int ret;
 742
 743         ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
 744         if (ret < 0) {
 745                 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
 746                 goto err_out;
 747         }
 748         return 0;
 749 err_out:
 750         return ret;
 751 }
 752
 753 static void __exit nfnl_cthelper_exit(void)
 754 {
 755         struct nf_conntrack_helper *cur;
 756         struct nfnl_cthelper *nlcth, *n;
 757
 758         nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
 759
 760         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 761                 cur = &nlcth->helper;
 762
 763                 nf_conntrack_helper_unregister(cur);
 764                 kfree(cur->expect_policy);
 765                 kfree(nlcth);
 766         }
 767 }
 768
 769 module_init(nfnl_cthelper_init);
 770 module_exit(nfnl_cthelper_exit);