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 {
 403         const char *helper_name;
 404         struct nf_conntrack_helper *cur, *helper = NULL;
 405         struct nf_conntrack_tuple tuple;
 406         struct nfnl_cthelper *nlcth;
 407         int ret = 0;
 408
 409         if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
 410                 return -EINVAL;
 411
 412         helper_name = nla_data(tb[NFCTH_NAME]);
 413
 414         ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 415         if (ret < 0)
 416                 return ret;
 417
 418         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 419                 cur = &nlcth->helper;
 420
 421                 if (strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 422                         continue;
 423
 424                 if ((tuple.src.l3num != cur->tuple.src.l3num ||
 425                      tuple.dst.protonum != cur->tuple.dst.protonum))
 426                         continue;
 427
 428                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 429                         return -EEXIST;
 430
 431                 helper = cur;
 432                 break;
 433         }
 434
 435         if (helper == NULL)
 436                 ret = nfnl_cthelper_create(tb, &tuple);
 437         else
 438                 ret = nfnl_cthelper_update(tb, helper);
 439
 440         return ret;
 441 }
 442
 443 static int
 444 nfnl_cthelper_dump_tuple(struct sk_buff *skb,
 445                          struct nf_conntrack_helper *helper)
 446 {
 447         struct nlattr *nest_parms;
 448
 449         nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
 450         if (nest_parms == NULL)
 451                 goto nla_put_failure;
 452
 453         if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
 454                          htons(helper->tuple.src.l3num)))
 455                 goto nla_put_failure;
 456
 457         if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
 458                 goto nla_put_failure;
 459
 460         nla_nest_end(skb, nest_parms);
 461         return 0;
 462
 463 nla_put_failure:
 464         return -1;
 465 }
 466
 467 static int
 468 nfnl_cthelper_dump_policy(struct sk_buff *skb,
 469                         struct nf_conntrack_helper *helper)
 470 {
 471         int i;
 472         struct nlattr *nest_parms1, *nest_parms2;
 473
 474         nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
 475         if (nest_parms1 == NULL)
 476                 goto nla_put_failure;
 477
 478         if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
 479                          htonl(helper->expect_class_max + 1)))
 480                 goto nla_put_failure;
 481
 482         for (i = 0; i < helper->expect_class_max + 1; i++) {
 483                 nest_parms2 = nla_nest_start(skb,
 484                                 (NFCTH_POLICY_SET+i) | NLA_F_NESTED);
 485                 if (nest_parms2 == NULL)
 486                         goto nla_put_failure;
 487
 488                 if (nla_put_string(skb, NFCTH_POLICY_NAME,
 489                                    helper->expect_policy[i].name))
 490                         goto nla_put_failure;
 491
 492                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
 493                                  htonl(helper->expect_policy[i].max_expected)))
 494                         goto nla_put_failure;
 495
 496                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
 497                                  htonl(helper->expect_policy[i].timeout)))
 498                         goto nla_put_failure;
 499
 500                 nla_nest_end(skb, nest_parms2);
 501         }
 502         nla_nest_end(skb, nest_parms1);
 503         return 0;
 504
 505 nla_put_failure:
 506         return -1;
 507 }
 508
 509 static int
 510 nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 511                         int event, struct nf_conntrack_helper *helper)
 512 {
 513         struct nlmsghdr *nlh;
 514         struct nfgenmsg *nfmsg;
 515         unsigned int flags = portid ? NLM_F_MULTI : 0;
 516         int status;
 517
 518         event = nfnl_msg_type(NFNL_SUBSYS_CTHELPER, event);
 519         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 520         if (nlh == NULL)
 521                 goto nlmsg_failure;
 522
 523         nfmsg = nlmsg_data(nlh);
 524         nfmsg->nfgen_family = AF_UNSPEC;
 525         nfmsg->version = NFNETLINK_V0;
 526         nfmsg->res_id = 0;
 527
 528         if (nla_put_string(skb, NFCTH_NAME, helper->name))
 529                 goto nla_put_failure;
 530
 531         if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
 532                 goto nla_put_failure;
 533
 534         if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
 535                 goto nla_put_failure;
 536
 537         if (nfnl_cthelper_dump_policy(skb, helper) < 0)
 538                 goto nla_put_failure;
 539
 540         if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
 541                 goto nla_put_failure;
 542
 543         if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
 544                 status = NFCT_HELPER_STATUS_ENABLED;
 545         else
 546                 status = NFCT_HELPER_STATUS_DISABLED;
 547
 548         if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
 549                 goto nla_put_failure;
 550
 551         nlmsg_end(skb, nlh);
 552         return skb->len;
 553
 554 nlmsg_failure:
 555 nla_put_failure:
 556         nlmsg_cancel(skb, nlh);
 557         return -1;
 558 }
 559
 560 static int
 561 nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
 562 {
 563         struct nf_conntrack_helper *cur, *last;
 564
 565         rcu_read_lock();
 566         last = (struct nf_conntrack_helper *)cb->args[1];
 567         for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
 568 restart:
 569                 hlist_for_each_entry_rcu(cur,
 570                                 &nf_ct_helper_hash[cb->args[0]], hnode) {
 571
 572                         /* skip non-userspace conntrack helpers. */
 573                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 574                                 continue;
 575
 576                         if (cb->args[1]) {
 577                                 if (cur != last)
 578                                         continue;
 579                                 cb->args[1] = 0;
 580                         }
 581                         if (nfnl_cthelper_fill_info(skb,
 582                                             NETLINK_CB(cb->skb).portid,
 583                                             cb->nlh->nlmsg_seq,
 584                                             NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 585                                             NFNL_MSG_CTHELPER_NEW, cur) < 0) {
 586                                 cb->args[1] = (unsigned long)cur;
 587                                 goto out;
 588                         }
 589                 }
 590         }
 591         if (cb->args[1]) {
 592                 cb->args[1] = 0;
 593                 goto restart;
 594         }
 595 out:
 596         rcu_read_unlock();
 597         return skb->len;
 598 }
 599
 600 static int nfnl_cthelper_get(struct net *net, struct sock *nfnl,
 601                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 602                              const struct nlattr * const tb[])
 603 {
 604         int ret = -ENOENT;
 605         struct nf_conntrack_helper *cur;
 606         struct sk_buff *skb2;
 607         char *helper_name = NULL;
 608         struct nf_conntrack_tuple tuple;
 609         struct nfnl_cthelper *nlcth;
 610         bool tuple_set = false;
 611
 612         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 613                 struct netlink_dump_control c = {
 614                         .dump = nfnl_cthelper_dump_table,
 615                 };
 616                 return netlink_dump_start(nfnl, skb, nlh, &c);
 617         }
 618
 619         if (tb[NFCTH_NAME])
 620                 helper_name = nla_data(tb[NFCTH_NAME]);
 621
 622         if (tb[NFCTH_TUPLE]) {
 623                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 624                 if (ret < 0)
 625                         return ret;
 626
 627                 tuple_set = true;
 628         }
 629
 630         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 631                 cur = &nlcth->helper;
 632                 if (helper_name &&
 633                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 634                         continue;
 635
 636                 if (tuple_set &&
 637                     (tuple.src.l3num != cur->tuple.src.l3num ||
 638                      tuple.dst.protonum != cur->tuple.dst.protonum))
 639                         continue;
 640
 641                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 642                 if (skb2 == NULL) {
 643                         ret = -ENOMEM;
 644                         break;
 645                 }
 646
 647                 ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
 648                                               nlh->nlmsg_seq,
 649                                               NFNL_MSG_TYPE(nlh->nlmsg_type),
 650                                               NFNL_MSG_CTHELPER_NEW, cur);
 651                 if (ret <= 0) {
 652                         kfree_skb(skb2);
 653                         break;
 654                 }
 655
 656                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 657                                       MSG_DONTWAIT);
 658                 if (ret > 0)
 659                         ret = 0;
 660
 661                 /* this avoids a loop in nfnetlink. */
 662                 return ret == -EAGAIN ? -ENOBUFS : ret;
 663         }
 664         return ret;
 665 }
 666
 667 static int nfnl_cthelper_del(struct net *net, struct sock *nfnl,
 668                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 669                              const struct nlattr * const tb[])
 670 {
 671         char *helper_name = NULL;
 672         struct nf_conntrack_helper *cur;
 673         struct nf_conntrack_tuple tuple;
 674         bool tuple_set = false, found = false;
 675         struct nfnl_cthelper *nlcth, *n;
 676         int j = 0, ret;
 677
 678         if (tb[NFCTH_NAME])
 679                 helper_name = nla_data(tb[NFCTH_NAME]);
 680
 681         if (tb[NFCTH_TUPLE]) {
 682                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 683                 if (ret < 0)
 684                         return ret;
 685
 686                 tuple_set = true;
 687         }
 688
 689         ret = -ENOENT;
 690         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 691                 cur = &nlcth->helper;
 692                 j++;
 693
 694                 if (helper_name &&
 695                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 696                         continue;
 697
 698                 if (tuple_set &&
 699                     (tuple.src.l3num != cur->tuple.src.l3num ||
 700                      tuple.dst.protonum != cur->tuple.dst.protonum))
 701                         continue;
 702
 703                 if (refcount_dec_if_one(&cur->refcnt)) {
 704                         found = true;
 705                         nf_conntrack_helper_unregister(cur);
 706                         kfree(cur->expect_policy);
 707
 708                         list_del(&nlcth->list);
 709                         kfree(nlcth);
 710                 } else {
 711                         ret = -EBUSY;
 712                 }
 713         }
 714
 715         /* Make sure we return success if we flush and there is no helpers */
 716         return (found || j == 0) ? 0 : ret;
 717 }
 718
 719 static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
 720         [NFCTH_NAME] = { .type = NLA_NUL_STRING,
 721                          .len = NF_CT_HELPER_NAME_LEN-1 },
 722         [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
 723 };
 724
 725 static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
 726         [NFNL_MSG_CTHELPER_NEW]         = { .call = nfnl_cthelper_new,
 727                                             .attr_count = NFCTH_MAX,
 728                                             .policy = nfnl_cthelper_policy },
 729         [NFNL_MSG_CTHELPER_GET]         = { .call = nfnl_cthelper_get,
 730                                             .attr_count = NFCTH_MAX,
 731                                             .policy = nfnl_cthelper_policy },
 732         [NFNL_MSG_CTHELPER_DEL]         = { .call = nfnl_cthelper_del,
 733                                             .attr_count = NFCTH_MAX,
 734                                             .policy = nfnl_cthelper_policy },
 735 };
 736
 737 static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
 738         .name                           = "cthelper",
 739         .subsys_id                      = NFNL_SUBSYS_CTHELPER,
 740         .cb_count                       = NFNL_MSG_CTHELPER_MAX,
 741         .cb                             = nfnl_cthelper_cb,
 742 };
 743
 744 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
 745
 746 static int __init nfnl_cthelper_init(void)
 747 {
 748         int ret;
 749
 750         ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
 751         if (ret < 0) {
 752                 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
 753                 goto err_out;
 754         }
 755         return 0;
 756 err_out:
 757         return ret;
 758 }
 759
 760 static void __exit nfnl_cthelper_exit(void)
 761 {
 762         struct nf_conntrack_helper *cur;
 763         struct nfnl_cthelper *nlcth, *n;
 764
 765         nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
 766
 767         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 768                 cur = &nlcth->helper;
 769
 770                 nf_conntrack_helper_unregister(cur);
 771                 kfree(cur->expect_policy);
 772                 kfree(nlcth);
 773         }
 774 }
 775
 776 module_init(nfnl_cthelper_init);
 777 module_exit(nfnl_cthelper_exit);