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         nla_memcpy(help->data, nla_data(attr), sizeof(help->data));
 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         if (expect_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
 156                 return -EINVAL;
 157
 158         expect_policy->timeout =
 159                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 160
 161         return 0;
 162 }
 163
 164 static const struct nla_policy
 165 nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
 166         [NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, },
 167 };
 168
 169 static int
 170 nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper,
 171                                   const struct nlattr *attr)
 172 {
 173         int i, ret;
 174         struct nf_conntrack_expect_policy *expect_policy;
 175         struct nlattr *tb[NFCTH_POLICY_SET_MAX+1];
 176         unsigned int class_max;
 177
 178         ret = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
 179                                nfnl_cthelper_expect_policy_set, NULL);
 180         if (ret < 0)
 181                 return ret;
 182
 183         if (!tb[NFCTH_POLICY_SET_NUM])
 184                 return -EINVAL;
 185
 186         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 187         if (class_max == 0)
 188                 return -EINVAL;
 189         if (class_max > NF_CT_MAX_EXPECT_CLASSES)
 190                 return -EOVERFLOW;
 191
 192         expect_policy = kzalloc(sizeof(struct nf_conntrack_expect_policy) *
 193                                 class_max, GFP_KERNEL);
 194         if (expect_policy == NULL)
 195                 return -ENOMEM;
 196
 197         for (i = 0; i < class_max; i++) {
 198                 if (!tb[NFCTH_POLICY_SET+i])
 199                         goto err;
 200
 201                 ret = nfnl_cthelper_expect_policy(&expect_policy[i],
 202                                                   tb[NFCTH_POLICY_SET+i]);
 203                 if (ret < 0)
 204                         goto err;
 205         }
 206
 207         helper->expect_class_max = class_max - 1;
 208         helper->expect_policy = expect_policy;
 209         return 0;
 210 err:
 211         kfree(expect_policy);
 212         return -EINVAL;
 213 }
 214
 215 static int
 216 nfnl_cthelper_create(const struct nlattr * const tb[],
 217                      struct nf_conntrack_tuple *tuple)
 218 {
 219         struct nf_conntrack_helper *helper;
 220         struct nfnl_cthelper *nfcth;
 221         unsigned int size;
 222         int ret;
 223
 224         if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
 225                 return -EINVAL;
 226
 227         nfcth = kzalloc(sizeof(*nfcth), GFP_KERNEL);
 228         if (nfcth == NULL)
 229                 return -ENOMEM;
 230         helper = &nfcth->helper;
 231
 232         ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
 233         if (ret < 0)
 234                 goto err1;
 235
 236         strncpy(helper->name, nla_data(tb[NFCTH_NAME]), NF_CT_HELPER_NAME_LEN);
 237         size = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
 238         if (size > FIELD_SIZEOF(struct nf_conn_help, data)) {
 239                 ret = -ENOMEM;
 240                 goto err2;
 241         }
 242
 243         helper->flags |= NF_CT_HELPER_F_USERSPACE;
 244         memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
 245
 246         helper->me = THIS_MODULE;
 247         helper->help = nfnl_userspace_cthelper;
 248         helper->from_nlattr = nfnl_cthelper_from_nlattr;
 249         helper->to_nlattr = nfnl_cthelper_to_nlattr;
 250
 251         /* Default to queue number zero, this can be updated at any time. */
 252         if (tb[NFCTH_QUEUE_NUM])
 253                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 254
 255         if (tb[NFCTH_STATUS]) {
 256                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 257
 258                 switch(status) {
 259                 case NFCT_HELPER_STATUS_ENABLED:
 260                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 261                         break;
 262                 case NFCT_HELPER_STATUS_DISABLED:
 263                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 264                         break;
 265                 }
 266         }
 267
 268         ret = nf_conntrack_helper_register(helper);
 269         if (ret < 0)
 270                 goto err2;
 271
 272         list_add_tail(&nfcth->list, &nfnl_cthelper_list);
 273         return 0;
 274 err2:
 275         kfree(helper->expect_policy);
 276 err1:
 277         kfree(nfcth);
 278         return ret;
 279 }
 280
 281 static int
 282 nfnl_cthelper_update_policy_one(const struct nf_conntrack_expect_policy *policy,
 283                                 struct nf_conntrack_expect_policy *new_policy,
 284                                 const struct nlattr *attr)
 285 {
 286         struct nlattr *tb[NFCTH_POLICY_MAX + 1];
 287         int err;
 288
 289         err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr,
 290                                nfnl_cthelper_expect_pol, NULL);
 291         if (err < 0)
 292                 return err;
 293
 294         if (!tb[NFCTH_POLICY_NAME] ||
 295             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 296             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 297                 return -EINVAL;
 298
 299         if (nla_strcmp(tb[NFCTH_POLICY_NAME], policy->name))
 300                 return -EBUSY;
 301
 302         new_policy->max_expected =
 303                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 304         if (new_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
 305                 return -EINVAL;
 306
 307         new_policy->timeout =
 308                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 309
 310         return 0;
 311 }
 312
 313 static int nfnl_cthelper_update_policy_all(struct nlattr *tb[],
 314                                            struct nf_conntrack_helper *helper)
 315 {
 316         struct nf_conntrack_expect_policy new_policy[helper->expect_class_max + 1];
 317         struct nf_conntrack_expect_policy *policy;
 318         int i, err;
 319
 320         /* Check first that all policy attributes are well-formed, so we don't
 321          * leave things in inconsistent state on errors.
 322          */
 323         for (i = 0; i < helper->expect_class_max + 1; i++) {
 324
 325                 if (!tb[NFCTH_POLICY_SET + i])
 326                         return -EINVAL;
 327
 328                 err = nfnl_cthelper_update_policy_one(&helper->expect_policy[i],
 329                                                       &new_policy[i],
 330                                                       tb[NFCTH_POLICY_SET + i]);
 331                 if (err < 0)
 332                         return err;
 333         }
 334         /* Now we can safely update them. */
 335         for (i = 0; i < helper->expect_class_max + 1; i++) {
 336                 policy = (struct nf_conntrack_expect_policy *)
 337                                 &helper->expect_policy[i];
 338                 policy->max_expected = new_policy->max_expected;
 339                 policy->timeout = new_policy->timeout;
 340         }
 341
 342         return 0;
 343 }
 344
 345 static int nfnl_cthelper_update_policy(struct nf_conntrack_helper *helper,
 346                                        const struct nlattr *attr)
 347 {
 348         struct nlattr *tb[NFCTH_POLICY_SET_MAX + 1];
 349         unsigned int class_max;
 350         int err;
 351
 352         err = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
 353                                nfnl_cthelper_expect_policy_set, NULL);
 354         if (err < 0)
 355                 return err;
 356
 357         if (!tb[NFCTH_POLICY_SET_NUM])
 358                 return -EINVAL;
 359
 360         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 361         if (helper->expect_class_max + 1 != class_max)
 362                 return -EBUSY;
 363
 364         return nfnl_cthelper_update_policy_all(tb, helper);
 365 }
 366
 367 static int
 368 nfnl_cthelper_update(const struct nlattr * const tb[],
 369                      struct nf_conntrack_helper *helper)
 370 {
 371         int ret;
 372
 373         if (tb[NFCTH_PRIV_DATA_LEN])
 374                 return -EBUSY;
 375
 376         if (tb[NFCTH_POLICY]) {
 377                 ret = nfnl_cthelper_update_policy(helper, tb[NFCTH_POLICY]);
 378                 if (ret < 0)
 379                         return ret;
 380         }
 381         if (tb[NFCTH_QUEUE_NUM])
 382                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 383
 384         if (tb[NFCTH_STATUS]) {
 385                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 386
 387                 switch(status) {
 388                 case NFCT_HELPER_STATUS_ENABLED:
 389                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 390                         break;
 391                 case NFCT_HELPER_STATUS_DISABLED:
 392                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 393                         break;
 394                 }
 395         }
 396         return 0;
 397 }
 398
 399 static int nfnl_cthelper_new(struct net *net, struct sock *nfnl,
 400                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 401                              const struct nlattr * const tb[],
 402                              struct netlink_ext_ack *extack)
 403 {
 404         const char *helper_name;
 405         struct nf_conntrack_helper *cur, *helper = NULL;
 406         struct nf_conntrack_tuple tuple;
 407         struct nfnl_cthelper *nlcth;
 408         int ret = 0;
 409
 410         if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
 411                 return -EINVAL;
 412
 413         helper_name = nla_data(tb[NFCTH_NAME]);
 414
 415         ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 416         if (ret < 0)
 417                 return ret;
 418
 419         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 420                 cur = &nlcth->helper;
 421
 422                 if (strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 423                         continue;
 424
 425                 if ((tuple.src.l3num != cur->tuple.src.l3num ||
 426                      tuple.dst.protonum != cur->tuple.dst.protonum))
 427                         continue;
 428
 429                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 430                         return -EEXIST;
 431
 432                 helper = cur;
 433                 break;
 434         }
 435
 436         if (helper == NULL)
 437                 ret = nfnl_cthelper_create(tb, &tuple);
 438         else
 439                 ret = nfnl_cthelper_update(tb, helper);
 440
 441         return ret;
 442 }
 443
 444 static int
 445 nfnl_cthelper_dump_tuple(struct sk_buff *skb,
 446                          struct nf_conntrack_helper *helper)
 447 {
 448         struct nlattr *nest_parms;
 449
 450         nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
 451         if (nest_parms == NULL)
 452                 goto nla_put_failure;
 453
 454         if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
 455                          htons(helper->tuple.src.l3num)))
 456                 goto nla_put_failure;
 457
 458         if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
 459                 goto nla_put_failure;
 460
 461         nla_nest_end(skb, nest_parms);
 462         return 0;
 463
 464 nla_put_failure:
 465         return -1;
 466 }
 467
 468 static int
 469 nfnl_cthelper_dump_policy(struct sk_buff *skb,
 470                         struct nf_conntrack_helper *helper)
 471 {
 472         int i;
 473         struct nlattr *nest_parms1, *nest_parms2;
 474
 475         nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
 476         if (nest_parms1 == NULL)
 477                 goto nla_put_failure;
 478
 479         if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
 480                          htonl(helper->expect_class_max + 1)))
 481                 goto nla_put_failure;
 482
 483         for (i = 0; i < helper->expect_class_max + 1; i++) {
 484                 nest_parms2 = nla_nest_start(skb,
 485                                 (NFCTH_POLICY_SET+i) | NLA_F_NESTED);
 486                 if (nest_parms2 == NULL)
 487                         goto nla_put_failure;
 488
 489                 if (nla_put_string(skb, NFCTH_POLICY_NAME,
 490                                    helper->expect_policy[i].name))
 491                         goto nla_put_failure;
 492
 493                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
 494                                  htonl(helper->expect_policy[i].max_expected)))
 495                         goto nla_put_failure;
 496
 497                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
 498                                  htonl(helper->expect_policy[i].timeout)))
 499                         goto nla_put_failure;
 500
 501                 nla_nest_end(skb, nest_parms2);
 502         }
 503         nla_nest_end(skb, nest_parms1);
 504         return 0;
 505
 506 nla_put_failure:
 507         return -1;
 508 }
 509
 510 static int
 511 nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 512                         int event, struct nf_conntrack_helper *helper)
 513 {
 514         struct nlmsghdr *nlh;
 515         struct nfgenmsg *nfmsg;
 516         unsigned int flags = portid ? NLM_F_MULTI : 0;
 517         int status;
 518
 519         event = nfnl_msg_type(NFNL_SUBSYS_CTHELPER, event);
 520         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 521         if (nlh == NULL)
 522                 goto nlmsg_failure;
 523
 524         nfmsg = nlmsg_data(nlh);
 525         nfmsg->nfgen_family = AF_UNSPEC;
 526         nfmsg->version = NFNETLINK_V0;
 527         nfmsg->res_id = 0;
 528
 529         if (nla_put_string(skb, NFCTH_NAME, helper->name))
 530                 goto nla_put_failure;
 531
 532         if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
 533                 goto nla_put_failure;
 534
 535         if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
 536                 goto nla_put_failure;
 537
 538         if (nfnl_cthelper_dump_policy(skb, helper) < 0)
 539                 goto nla_put_failure;
 540
 541         if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
 542                 goto nla_put_failure;
 543
 544         if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
 545                 status = NFCT_HELPER_STATUS_ENABLED;
 546         else
 547                 status = NFCT_HELPER_STATUS_DISABLED;
 548
 549         if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
 550                 goto nla_put_failure;
 551
 552         nlmsg_end(skb, nlh);
 553         return skb->len;
 554
 555 nlmsg_failure:
 556 nla_put_failure:
 557         nlmsg_cancel(skb, nlh);
 558         return -1;
 559 }
 560
 561 static int
 562 nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
 563 {
 564         struct nf_conntrack_helper *cur, *last;
 565
 566         rcu_read_lock();
 567         last = (struct nf_conntrack_helper *)cb->args[1];
 568         for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
 569 restart:
 570                 hlist_for_each_entry_rcu(cur,
 571                                 &nf_ct_helper_hash[cb->args[0]], hnode) {
 572
 573                         /* skip non-userspace conntrack helpers. */
 574                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 575                                 continue;
 576
 577                         if (cb->args[1]) {
 578                                 if (cur != last)
 579                                         continue;
 580                                 cb->args[1] = 0;
 581                         }
 582                         if (nfnl_cthelper_fill_info(skb,
 583                                             NETLINK_CB(cb->skb).portid,
 584                                             cb->nlh->nlmsg_seq,
 585                                             NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 586                                             NFNL_MSG_CTHELPER_NEW, cur) < 0) {
 587                                 cb->args[1] = (unsigned long)cur;
 588                                 goto out;
 589                         }
 590                 }
 591         }
 592         if (cb->args[1]) {
 593                 cb->args[1] = 0;
 594                 goto restart;
 595         }
 596 out:
 597         rcu_read_unlock();
 598         return skb->len;
 599 }
 600
 601 static int nfnl_cthelper_get(struct net *net, struct sock *nfnl,
 602                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 603                              const struct nlattr * const tb[],
 604                              struct netlink_ext_ack *extack)
 605 {
 606         int ret = -ENOENT;
 607         struct nf_conntrack_helper *cur;
 608         struct sk_buff *skb2;
 609         char *helper_name = NULL;
 610         struct nf_conntrack_tuple tuple;
 611         struct nfnl_cthelper *nlcth;
 612         bool tuple_set = false;
 613
 614         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 615                 struct netlink_dump_control c = {
 616                         .dump = nfnl_cthelper_dump_table,
 617                 };
 618                 return netlink_dump_start(nfnl, skb, nlh, &c);
 619         }
 620
 621         if (tb[NFCTH_NAME])
 622                 helper_name = nla_data(tb[NFCTH_NAME]);
 623
 624         if (tb[NFCTH_TUPLE]) {
 625                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 626                 if (ret < 0)
 627                         return ret;
 628
 629                 tuple_set = true;
 630         }
 631
 632         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 633                 cur = &nlcth->helper;
 634                 if (helper_name &&
 635                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 636                         continue;
 637
 638                 if (tuple_set &&
 639                     (tuple.src.l3num != cur->tuple.src.l3num ||
 640                      tuple.dst.protonum != cur->tuple.dst.protonum))
 641                         continue;
 642
 643                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 644                 if (skb2 == NULL) {
 645                         ret = -ENOMEM;
 646                         break;
 647                 }
 648
 649                 ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
 650                                               nlh->nlmsg_seq,
 651                                               NFNL_MSG_TYPE(nlh->nlmsg_type),
 652                                               NFNL_MSG_CTHELPER_NEW, cur);
 653                 if (ret <= 0) {
 654                         kfree_skb(skb2);
 655                         break;
 656                 }
 657
 658                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 659                                       MSG_DONTWAIT);
 660                 if (ret > 0)
 661                         ret = 0;
 662
 663                 /* this avoids a loop in nfnetlink. */
 664                 return ret == -EAGAIN ? -ENOBUFS : ret;
 665         }
 666         return ret;
 667 }
 668
 669 static int nfnl_cthelper_del(struct net *net, struct sock *nfnl,
 670                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 671                              const struct nlattr * const tb[],
 672                              struct netlink_ext_ack *extack)
 673 {
 674         char *helper_name = NULL;
 675         struct nf_conntrack_helper *cur;
 676         struct nf_conntrack_tuple tuple;
 677         bool tuple_set = false, found = false;
 678         struct nfnl_cthelper *nlcth, *n;
 679         int j = 0, ret;
 680
 681         if (tb[NFCTH_NAME])
 682                 helper_name = nla_data(tb[NFCTH_NAME]);
 683
 684         if (tb[NFCTH_TUPLE]) {
 685                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 686                 if (ret < 0)
 687                         return ret;
 688
 689                 tuple_set = true;
 690         }
 691
 692         ret = -ENOENT;
 693         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 694                 cur = &nlcth->helper;
 695                 j++;
 696
 697                 if (helper_name &&
 698                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 699                         continue;
 700
 701                 if (tuple_set &&
 702                     (tuple.src.l3num != cur->tuple.src.l3num ||
 703                      tuple.dst.protonum != cur->tuple.dst.protonum))
 704                         continue;
 705
 706                 if (refcount_dec_if_one(&cur->refcnt)) {
 707                         found = true;
 708                         nf_conntrack_helper_unregister(cur);
 709                         kfree(cur->expect_policy);
 710
 711                         list_del(&nlcth->list);
 712                         kfree(nlcth);
 713                 } else {
 714                         ret = -EBUSY;
 715                 }
 716         }
 717
 718         /* Make sure we return success if we flush and there is no helpers */
 719         return (found || j == 0) ? 0 : ret;
 720 }
 721
 722 static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
 723         [NFCTH_NAME] = { .type = NLA_NUL_STRING,
 724                          .len = NF_CT_HELPER_NAME_LEN-1 },
 725         [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
 726 };
 727
 728 static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
 729         [NFNL_MSG_CTHELPER_NEW]         = { .call = nfnl_cthelper_new,
 730                                             .attr_count = NFCTH_MAX,
 731                                             .policy = nfnl_cthelper_policy },
 732         [NFNL_MSG_CTHELPER_GET]         = { .call = nfnl_cthelper_get,
 733                                             .attr_count = NFCTH_MAX,
 734                                             .policy = nfnl_cthelper_policy },
 735         [NFNL_MSG_CTHELPER_DEL]         = { .call = nfnl_cthelper_del,
 736                                             .attr_count = NFCTH_MAX,
 737                                             .policy = nfnl_cthelper_policy },
 738 };
 739
 740 static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
 741         .name                           = "cthelper",
 742         .subsys_id                      = NFNL_SUBSYS_CTHELPER,
 743         .cb_count                       = NFNL_MSG_CTHELPER_MAX,
 744         .cb                             = nfnl_cthelper_cb,
 745 };
 746
 747 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
 748
 749 static int __init nfnl_cthelper_init(void)
 750 {
 751         int ret;
 752
 753         ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
 754         if (ret < 0) {
 755                 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
 756                 goto err_out;
 757         }
 758         return 0;
 759 err_out:
 760         return ret;
 761 }
 762
 763 static void __exit nfnl_cthelper_exit(void)
 764 {
 765         struct nf_conntrack_helper *cur;
 766         struct nfnl_cthelper *nlcth, *n;
 767
 768         nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
 769
 770         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 771                 cur = &nlcth->helper;
 772
 773                 nf_conntrack_helper_unregister(cur);
 774                 kfree(cur->expect_policy);
 775                 kfree(nlcth);
 776         }
 777 }
 778
 779 module_init(nfnl_cthelper_init);
 780 module_exit(nfnl_cthelper_exit);