net/netfilter/nfnetlink_cthelper.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * (C) 2012 Pablo Neira Ayuso <pablo@netfilter.org>
   4  *
   5  * This software has been sponsored by Vyatta Inc. <http://www.vyatta.com>
   6  */
   7 #include <linux/init.h>
   8 #include <linux/module.h>
   9 #include <linux/kernel.h>
  10 #include <linux/skbuff.h>
  11 #include <linux/netlink.h>
  12 #include <linux/rculist.h>
  13 #include <linux/slab.h>
  14 #include <linux/types.h>
  15 #include <linux/list.h>
  16 #include <linux/errno.h>
  17 #include <linux/capability.h>
  18 #include <net/netlink.h>
  19 #include <net/sock.h>
  20
  21 #include <net/netfilter/nf_conntrack_helper.h>
  22 #include <net/netfilter/nf_conntrack_expect.h>
  23 #include <net/netfilter/nf_conntrack_ecache.h>
  24
  25 #include <linux/netfilter/nfnetlink.h>
  26 #include <linux/netfilter/nfnetlink_conntrack.h>
  27 #include <linux/netfilter/nfnetlink_cthelper.h>
  28
  29 MODULE_LICENSE("GPL");
  30 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
  31 MODULE_DESCRIPTION("nfnl_cthelper: User-space connection tracking helpers");
  32
  33 struct nfnl_cthelper {
  34         struct list_head                list;
  35         struct nf_conntrack_helper      helper;
  36 };
  37
  38 static LIST_HEAD(nfnl_cthelper_list);
  39
  40 static int
  41 nfnl_userspace_cthelper(struct sk_buff *skb, unsigned int protoff,
  42                         struct nf_conn *ct, enum ip_conntrack_info ctinfo)
  43 {
  44         const struct nf_conn_help *help;
  45         struct nf_conntrack_helper *helper;
  46
  47         help = nfct_help(ct);
  48         if (help == NULL)
  49                 return NF_DROP;
  50
  51         /* rcu_read_lock()ed by nf_hook_thresh */
  52         helper = rcu_dereference(help->helper);
  53         if (helper == NULL)
  54                 return NF_DROP;
  55
  56         /* This is a user-space helper not yet configured, skip. */
  57         if ((helper->flags &
  58             (NF_CT_HELPER_F_USERSPACE | NF_CT_HELPER_F_CONFIGURED)) ==
  59              NF_CT_HELPER_F_USERSPACE)
  60                 return NF_ACCEPT;
  61
  62         /* If the user-space helper is not available, don't block traffic. */
  63         return NF_QUEUE_NR(helper->queue_num) | NF_VERDICT_FLAG_QUEUE_BYPASS;
  64 }
  65
  66 static const struct nla_policy nfnl_cthelper_tuple_pol[NFCTH_TUPLE_MAX+1] = {
  67         [NFCTH_TUPLE_L3PROTONUM] = { .type = NLA_U16, },
  68         [NFCTH_TUPLE_L4PROTONUM] = { .type = NLA_U8, },
  69 };
  70
  71 static int
  72 nfnl_cthelper_parse_tuple(struct nf_conntrack_tuple *tuple,
  73                           const struct nlattr *attr)
  74 {
  75         int err;
  76         struct nlattr *tb[NFCTH_TUPLE_MAX+1];
  77
  78         err = nla_parse_nested_deprecated(tb, NFCTH_TUPLE_MAX, attr,
  79                                           nfnl_cthelper_tuple_pol, NULL);
  80         if (err < 0)
  81                 return err;
  82
  83         if (!tb[NFCTH_TUPLE_L3PROTONUM] || !tb[NFCTH_TUPLE_L4PROTONUM])
  84                 return -EINVAL;
  85
  86         /* Not all fields are initialized so first zero the tuple */
  87         memset(tuple, 0, sizeof(struct nf_conntrack_tuple));
  88
  89         tuple->src.l3num = ntohs(nla_get_be16(tb[NFCTH_TUPLE_L3PROTONUM]));
  90         tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]);
  91
  92         return 0;
  93 }
  94
  95 static int
  96 nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
  97 {
  98         struct nf_conn_help *help = nfct_help(ct);
  99         const struct nf_conntrack_helper *helper;
 100
 101         if (attr == NULL)
 102                 return -EINVAL;
 103
 104         helper = rcu_dereference(help->helper);
 105         if (!helper || helper->data_len == 0)
 106                 return -EINVAL;
 107
 108         nla_memcpy(help->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         const struct nf_conntrack_helper *helper;
 117
 118         helper = rcu_dereference(help->helper);
 119         if (helper && helper->data_len &&
 120             nla_put(skb, CTA_HELP_INFO, helper->data_len, &help->data))
 121                 goto nla_put_failure;
 122
 123         return 0;
 124
 125 nla_put_failure:
 126         return -ENOSPC;
 127 }
 128
 129 static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = {
 130         [NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING,
 131                                 .len = NF_CT_HELPER_NAME_LEN-1 },
 132         [NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, },
 133         [NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, },
 134 };
 135
 136 static int
 137 nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy,
 138                             const struct nlattr *attr)
 139 {
 140         int err;
 141         struct nlattr *tb[NFCTH_POLICY_MAX+1];
 142
 143         err = nla_parse_nested_deprecated(tb, NFCTH_POLICY_MAX, attr,
 144                                           nfnl_cthelper_expect_pol, NULL);
 145         if (err < 0)
 146                 return err;
 147
 148         if (!tb[NFCTH_POLICY_NAME] ||
 149             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 150             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 151                 return -EINVAL;
 152
 153         nla_strscpy(expect_policy->name,
 154                     tb[NFCTH_POLICY_NAME], NF_CT_HELPER_NAME_LEN);
 155         expect_policy->max_expected =
 156                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 157         if (expect_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
 158                 return -EINVAL;
 159
 160         expect_policy->timeout =
 161                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 162
 163         return 0;
 164 }
 165
 166 static const struct nla_policy
 167 nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
 168         [NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, },
 169 };
 170
 171 static int
 172 nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper,
 173                                   const struct nlattr *attr)
 174 {
 175         int i, ret;
 176         struct nf_conntrack_expect_policy *expect_policy;
 177         struct nlattr *tb[NFCTH_POLICY_SET_MAX+1];
 178         unsigned int class_max;
 179
 180         ret = nla_parse_nested_deprecated(tb, NFCTH_POLICY_SET_MAX, attr,
 181                                           nfnl_cthelper_expect_policy_set,
 182                                           NULL);
 183         if (ret < 0)
 184                 return ret;
 185
 186         if (!tb[NFCTH_POLICY_SET_NUM])
 187                 return -EINVAL;
 188
 189         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 190         if (class_max == 0)
 191                 return -EINVAL;
 192         if (class_max > NF_CT_MAX_EXPECT_CLASSES)
 193                 return -EOVERFLOW;
 194
 195         expect_policy = kcalloc(class_max,
 196                                 sizeof(struct nf_conntrack_expect_policy),
 197                                 GFP_KERNEL);
 198         if (expect_policy == NULL)
 199                 return -ENOMEM;
 200
 201         for (i = 0; i < class_max; i++) {
 202                 if (!tb[NFCTH_POLICY_SET+i])
 203                         goto err;
 204
 205                 ret = nfnl_cthelper_expect_policy(&expect_policy[i],
 206                                                   tb[NFCTH_POLICY_SET+i]);
 207                 if (ret < 0)
 208                         goto err;
 209         }
 210
 211         helper->expect_class_max = class_max - 1;
 212         helper->expect_policy = expect_policy;
 213         return 0;
 214 err:
 215         kfree(expect_policy);
 216         return -EINVAL;
 217 }
 218
 219 static int
 220 nfnl_cthelper_create(const struct nlattr * const tb[],
 221                      struct nf_conntrack_tuple *tuple)
 222 {
 223         struct nf_conntrack_helper *helper;
 224         struct nfnl_cthelper *nfcth;
 225         unsigned int size;
 226         int ret;
 227
 228         if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
 229                 return -EINVAL;
 230
 231         nfcth = kzalloc(sizeof(*nfcth), GFP_KERNEL);
 232         if (nfcth == NULL)
 233                 return -ENOMEM;
 234         helper = &nfcth->helper;
 235
 236         ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
 237         if (ret < 0)
 238                 goto err1;
 239
 240         nla_strscpy(helper->name,
 241                     tb[NFCTH_NAME], NF_CT_HELPER_NAME_LEN);
 242         size = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
 243         if (size > sizeof_field(struct nf_conn_help, data)) {
 244                 ret = -ENOMEM;
 245                 goto err2;
 246         }
 247         helper->data_len = size;
 248
 249         helper->flags |= NF_CT_HELPER_F_USERSPACE;
 250         memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
 251
 252         helper->me = THIS_MODULE;
 253         helper->help = nfnl_userspace_cthelper;
 254         helper->from_nlattr = nfnl_cthelper_from_nlattr;
 255         helper->to_nlattr = nfnl_cthelper_to_nlattr;
 256
 257         /* Default to queue number zero, this can be updated at any time. */
 258         if (tb[NFCTH_QUEUE_NUM])
 259                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 260
 261         if (tb[NFCTH_STATUS]) {
 262                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 263
 264                 switch(status) {
 265                 case NFCT_HELPER_STATUS_ENABLED:
 266                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 267                         break;
 268                 case NFCT_HELPER_STATUS_DISABLED:
 269                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 270                         break;
 271                 }
 272         }
 273
 274         ret = nf_conntrack_helper_register(helper);
 275         if (ret < 0)
 276                 goto err2;
 277
 278         list_add_tail(&nfcth->list, &nfnl_cthelper_list);
 279         return 0;
 280 err2:
 281         kfree(helper->expect_policy);
 282 err1:
 283         kfree(nfcth);
 284         return ret;
 285 }
 286
 287 static int
 288 nfnl_cthelper_update_policy_one(const struct nf_conntrack_expect_policy *policy,
 289                                 struct nf_conntrack_expect_policy *new_policy,
 290                                 const struct nlattr *attr)
 291 {
 292         struct nlattr *tb[NFCTH_POLICY_MAX + 1];
 293         int err;
 294
 295         err = nla_parse_nested_deprecated(tb, NFCTH_POLICY_MAX, attr,
 296                                           nfnl_cthelper_expect_pol, NULL);
 297         if (err < 0)
 298                 return err;
 299
 300         if (!tb[NFCTH_POLICY_NAME] ||
 301             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 302             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 303                 return -EINVAL;
 304
 305         if (nla_strcmp(tb[NFCTH_POLICY_NAME], policy->name))
 306                 return -EBUSY;
 307
 308         new_policy->max_expected =
 309                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 310         if (new_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
 311                 return -EINVAL;
 312
 313         new_policy->timeout =
 314                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 315
 316         return 0;
 317 }
 318
 319 static int nfnl_cthelper_update_policy_all(struct nlattr *tb[],
 320                                            struct nf_conntrack_helper *helper)
 321 {
 322         struct nf_conntrack_expect_policy *new_policy;
 323         struct nf_conntrack_expect_policy *policy;
 324         int i, ret = 0;
 325
 326         new_policy = kmalloc_array(helper->expect_class_max + 1,
 327                                    sizeof(*new_policy), GFP_KERNEL);
 328         if (!new_policy)
 329                 return -ENOMEM;
 330
 331         /* Check first that all policy attributes are well-formed, so we don't
 332          * leave things in inconsistent state on errors.
 333          */
 334         for (i = 0; i < helper->expect_class_max + 1; i++) {
 335
 336                 if (!tb[NFCTH_POLICY_SET + i]) {
 337                         ret = -EINVAL;
 338                         goto err;
 339                 }
 340
 341                 ret = nfnl_cthelper_update_policy_one(&helper->expect_policy[i],
 342                                                       &new_policy[i],
 343                                                       tb[NFCTH_POLICY_SET + i]);
 344                 if (ret < 0)
 345                         goto err;
 346         }
 347         /* Now we can safely update them. */
 348         for (i = 0; i < helper->expect_class_max + 1; i++) {
 349                 policy = (struct nf_conntrack_expect_policy *)
 350                                 &helper->expect_policy[i];
 351                 policy->max_expected = new_policy->max_expected;
 352                 policy->timeout = new_policy->timeout;
 353         }
 354
 355 err:
 356         kfree(new_policy);
 357         return ret;
 358 }
 359
 360 static int nfnl_cthelper_update_policy(struct nf_conntrack_helper *helper,
 361                                        const struct nlattr *attr)
 362 {
 363         struct nlattr *tb[NFCTH_POLICY_SET_MAX + 1];
 364         unsigned int class_max;
 365         int err;
 366
 367         err = nla_parse_nested_deprecated(tb, NFCTH_POLICY_SET_MAX, attr,
 368                                           nfnl_cthelper_expect_policy_set,
 369                                           NULL);
 370         if (err < 0)
 371                 return err;
 372
 373         if (!tb[NFCTH_POLICY_SET_NUM])
 374                 return -EINVAL;
 375
 376         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 377         if (helper->expect_class_max + 1 != class_max)
 378                 return -EBUSY;
 379
 380         return nfnl_cthelper_update_policy_all(tb, helper);
 381 }
 382
 383 static int
 384 nfnl_cthelper_update(const struct nlattr * const tb[],
 385                      struct nf_conntrack_helper *helper)
 386 {
 387         u32 size;
 388         int ret;
 389
 390         if (tb[NFCTH_PRIV_DATA_LEN]) {
 391                 size = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
 392                 if (size != helper->data_len)
 393                         return -EBUSY;
 394         }
 395
 396         if (tb[NFCTH_POLICY]) {
 397                 ret = nfnl_cthelper_update_policy(helper, tb[NFCTH_POLICY]);
 398                 if (ret < 0)
 399                         return ret;
 400         }
 401         if (tb[NFCTH_QUEUE_NUM])
 402                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 403
 404         if (tb[NFCTH_STATUS]) {
 405                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 406
 407                 switch(status) {
 408                 case NFCT_HELPER_STATUS_ENABLED:
 409                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 410                         break;
 411                 case NFCT_HELPER_STATUS_DISABLED:
 412                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 413                         break;
 414                 }
 415         }
 416         return 0;
 417 }
 418
 419 static int nfnl_cthelper_new(struct sk_buff *skb, const struct nfnl_info *info,
 420                              const struct nlattr * const tb[])
 421 {
 422         const char *helper_name;
 423         struct nf_conntrack_helper *cur, *helper = NULL;
 424         struct nf_conntrack_tuple tuple;
 425         struct nfnl_cthelper *nlcth;
 426         int ret = 0;
 427
 428         if (!capable(CAP_NET_ADMIN))
 429                 return -EPERM;
 430
 431         if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
 432                 return -EINVAL;
 433
 434         helper_name = nla_data(tb[NFCTH_NAME]);
 435
 436         ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 437         if (ret < 0)
 438                 return ret;
 439
 440         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 441                 cur = &nlcth->helper;
 442
 443                 if (strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 444                         continue;
 445
 446                 if ((tuple.src.l3num != cur->tuple.src.l3num ||
 447                      tuple.dst.protonum != cur->tuple.dst.protonum))
 448                         continue;
 449
 450                 if (info->nlh->nlmsg_flags & NLM_F_EXCL)
 451                         return -EEXIST;
 452
 453                 helper = cur;
 454                 break;
 455         }
 456
 457         if (helper == NULL)
 458                 ret = nfnl_cthelper_create(tb, &tuple);
 459         else
 460                 ret = nfnl_cthelper_update(tb, helper);
 461
 462         return ret;
 463 }
 464
 465 static int
 466 nfnl_cthelper_dump_tuple(struct sk_buff *skb,
 467                          struct nf_conntrack_helper *helper)
 468 {
 469         struct nlattr *nest_parms;
 470
 471         nest_parms = nla_nest_start(skb, NFCTH_TUPLE);
 472         if (nest_parms == NULL)
 473                 goto nla_put_failure;
 474
 475         if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
 476                          htons(helper->tuple.src.l3num)))
 477                 goto nla_put_failure;
 478
 479         if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
 480                 goto nla_put_failure;
 481
 482         nla_nest_end(skb, nest_parms);
 483         return 0;
 484
 485 nla_put_failure:
 486         return -1;
 487 }
 488
 489 static int
 490 nfnl_cthelper_dump_policy(struct sk_buff *skb,
 491                         struct nf_conntrack_helper *helper)
 492 {
 493         int i;
 494         struct nlattr *nest_parms1, *nest_parms2;
 495
 496         nest_parms1 = nla_nest_start(skb, NFCTH_POLICY);
 497         if (nest_parms1 == NULL)
 498                 goto nla_put_failure;
 499
 500         if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
 501                          htonl(helper->expect_class_max + 1)))
 502                 goto nla_put_failure;
 503
 504         for (i = 0; i < helper->expect_class_max + 1; i++) {
 505                 nest_parms2 = nla_nest_start(skb, (NFCTH_POLICY_SET + i));
 506                 if (nest_parms2 == NULL)
 507                         goto nla_put_failure;
 508
 509                 if (nla_put_string(skb, NFCTH_POLICY_NAME,
 510                                    helper->expect_policy[i].name))
 511                         goto nla_put_failure;
 512
 513                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
 514                                  htonl(helper->expect_policy[i].max_expected)))
 515                         goto nla_put_failure;
 516
 517                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
 518                                  htonl(helper->expect_policy[i].timeout)))
 519                         goto nla_put_failure;
 520
 521                 nla_nest_end(skb, nest_parms2);
 522         }
 523         nla_nest_end(skb, nest_parms1);
 524         return 0;
 525
 526 nla_put_failure:
 527         return -1;
 528 }
 529
 530 static int
 531 nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 532                         int event, struct nf_conntrack_helper *helper)
 533 {
 534         struct nlmsghdr *nlh;
 535         unsigned int flags = portid ? NLM_F_MULTI : 0;
 536         int status;
 537
 538         event = nfnl_msg_type(NFNL_SUBSYS_CTHELPER, event);
 539         nlh = nfnl_msg_put(skb, portid, seq, event, flags, AF_UNSPEC,
 540                            NFNETLINK_V0, 0);
 541         if (!nlh)
 542                 goto nlmsg_failure;
 543
 544         if (nla_put_string(skb, NFCTH_NAME, helper->name))
 545                 goto nla_put_failure;
 546
 547         if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
 548                 goto nla_put_failure;
 549
 550         if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
 551                 goto nla_put_failure;
 552
 553         if (nfnl_cthelper_dump_policy(skb, helper) < 0)
 554                 goto nla_put_failure;
 555
 556         if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
 557                 goto nla_put_failure;
 558
 559         if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
 560                 status = NFCT_HELPER_STATUS_ENABLED;
 561         else
 562                 status = NFCT_HELPER_STATUS_DISABLED;
 563
 564         if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
 565                 goto nla_put_failure;
 566
 567         nlmsg_end(skb, nlh);
 568         return skb->len;
 569
 570 nlmsg_failure:
 571 nla_put_failure:
 572         nlmsg_cancel(skb, nlh);
 573         return -1;
 574 }
 575
 576 static int
 577 nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
 578 {
 579         struct nf_conntrack_helper *cur, *last;
 580
 581         rcu_read_lock();
 582         last = (struct nf_conntrack_helper *)cb->args[1];
 583         for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
 584 restart:
 585                 hlist_for_each_entry_rcu(cur,
 586                                 &nf_ct_helper_hash[cb->args[0]], hnode) {
 587
 588                         /* skip non-userspace conntrack helpers. */
 589                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 590                                 continue;
 591
 592                         if (cb->args[1]) {
 593                                 if (cur != last)
 594                                         continue;
 595                                 cb->args[1] = 0;
 596                         }
 597                         if (nfnl_cthelper_fill_info(skb,
 598                                             NETLINK_CB(cb->skb).portid,
 599                                             cb->nlh->nlmsg_seq,
 600                                             NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 601                                             NFNL_MSG_CTHELPER_NEW, cur) < 0) {
 602                                 cb->args[1] = (unsigned long)cur;
 603                                 goto out;
 604                         }
 605                 }
 606         }
 607         if (cb->args[1]) {
 608                 cb->args[1] = 0;
 609                 goto restart;
 610         }
 611 out:
 612         rcu_read_unlock();
 613         return skb->len;
 614 }
 615
 616 static int nfnl_cthelper_get(struct sk_buff *skb, const struct nfnl_info *info,
 617                              const struct nlattr * const tb[])
 618 {
 619         int ret = -ENOENT;
 620         struct nf_conntrack_helper *cur;
 621         struct sk_buff *skb2;
 622         char *helper_name = NULL;
 623         struct nf_conntrack_tuple tuple;
 624         struct nfnl_cthelper *nlcth;
 625         bool tuple_set = false;
 626
 627         if (!capable(CAP_NET_ADMIN))
 628                 return -EPERM;
 629
 630         if (info->nlh->nlmsg_flags & NLM_F_DUMP) {
 631                 struct netlink_dump_control c = {
 632                         .dump = nfnl_cthelper_dump_table,
 633                 };
 634                 return netlink_dump_start(info->sk, skb, info->nlh, &c);
 635         }
 636
 637         if (tb[NFCTH_NAME])
 638                 helper_name = nla_data(tb[NFCTH_NAME]);
 639
 640         if (tb[NFCTH_TUPLE]) {
 641                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 642                 if (ret < 0)
 643                         return ret;
 644
 645                 tuple_set = true;
 646         }
 647
 648         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 649                 cur = &nlcth->helper;
 650                 if (helper_name &&
 651                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 652                         continue;
 653
 654                 if (tuple_set &&
 655                     (tuple.src.l3num != cur->tuple.src.l3num ||
 656                      tuple.dst.protonum != cur->tuple.dst.protonum))
 657                         continue;
 658
 659                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 660                 if (skb2 == NULL) {
 661                         ret = -ENOMEM;
 662                         break;
 663                 }
 664
 665                 ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
 666                                               info->nlh->nlmsg_seq,
 667                                               NFNL_MSG_TYPE(info->nlh->nlmsg_type),
 668                                               NFNL_MSG_CTHELPER_NEW, cur);
 669                 if (ret <= 0) {
 670                         kfree_skb(skb2);
 671                         break;
 672                 }
 673
 674                 ret = nfnetlink_unicast(skb2, info->net, NETLINK_CB(skb).portid);
 675                 break;
 676         }
 677
 678         return ret;
 679 }
 680
 681 static int nfnl_cthelper_del(struct sk_buff *skb, const struct nfnl_info *info,
 682                              const struct nlattr * const tb[])
 683 {
 684         char *helper_name = NULL;
 685         struct nf_conntrack_helper *cur;
 686         struct nf_conntrack_tuple tuple;
 687         bool tuple_set = false, found = false;
 688         struct nfnl_cthelper *nlcth, *n;
 689         int j = 0, ret;
 690
 691         if (!capable(CAP_NET_ADMIN))
 692                 return -EPERM;
 693
 694         if (tb[NFCTH_NAME])
 695                 helper_name = nla_data(tb[NFCTH_NAME]);
 696
 697         if (tb[NFCTH_TUPLE]) {
 698                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 699                 if (ret < 0)
 700                         return ret;
 701
 702                 tuple_set = true;
 703         }
 704
 705         ret = -ENOENT;
 706         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 707                 cur = &nlcth->helper;
 708                 j++;
 709
 710                 if (helper_name &&
 711                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 712                         continue;
 713
 714                 if (tuple_set &&
 715                     (tuple.src.l3num != cur->tuple.src.l3num ||
 716                      tuple.dst.protonum != cur->tuple.dst.protonum))
 717                         continue;
 718
 719                 if (refcount_dec_if_one(&cur->refcnt)) {
 720                         found = true;
 721                         nf_conntrack_helper_unregister(cur);
 722                         kfree(cur->expect_policy);
 723
 724                         list_del(&nlcth->list);
 725                         kfree(nlcth);
 726                 } else {
 727                         ret = -EBUSY;
 728                 }
 729         }
 730
 731         /* Make sure we return success if we flush and there is no helpers */
 732         return (found || j == 0) ? 0 : ret;
 733 }
 734
 735 static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
 736         [NFCTH_NAME] = { .type = NLA_NUL_STRING,
 737                          .len = NF_CT_HELPER_NAME_LEN-1 },
 738         [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
 739         [NFCTH_PRIV_DATA_LEN] = { .type = NLA_U32, },
 740         [NFCTH_STATUS] = { .type = NLA_U32, },
 741 };
 742
 743 static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
 744         [NFNL_MSG_CTHELPER_NEW] = {
 745                 .call           = nfnl_cthelper_new,
 746                 .type           = NFNL_CB_MUTEX,
 747                 .attr_count     = NFCTH_MAX,
 748                 .policy         = nfnl_cthelper_policy
 749         },
 750         [NFNL_MSG_CTHELPER_GET] = {
 751                 .call           = nfnl_cthelper_get,
 752                 .type           = NFNL_CB_MUTEX,
 753                 .attr_count     = NFCTH_MAX,
 754                 .policy         = nfnl_cthelper_policy
 755         },
 756         [NFNL_MSG_CTHELPER_DEL] = {
 757                 .call           = nfnl_cthelper_del,
 758                 .type           = NFNL_CB_MUTEX,
 759                 .attr_count     = NFCTH_MAX,
 760                 .policy         = nfnl_cthelper_policy
 761         },
 762 };
 763
 764 static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
 765         .name                           = "cthelper",
 766         .subsys_id                      = NFNL_SUBSYS_CTHELPER,
 767         .cb_count                       = NFNL_MSG_CTHELPER_MAX,
 768         .cb                             = nfnl_cthelper_cb,
 769 };
 770
 771 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
 772
 773 static int __init nfnl_cthelper_init(void)
 774 {
 775         int ret;
 776
 777         ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
 778         if (ret < 0) {
 779                 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
 780                 goto err_out;
 781         }
 782         return 0;
 783 err_out:
 784         return ret;
 785 }
 786
 787 static void __exit nfnl_cthelper_exit(void)
 788 {
 789         struct nf_conntrack_helper *cur;
 790         struct nfnl_cthelper *nlcth, *n;
 791
 792         nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
 793
 794         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 795                 cur = &nlcth->helper;
 796
 797                 nf_conntrack_helper_unregister(cur);
 798                 kfree(cur->expect_policy);
 799                 kfree(nlcth);
 800         }
 801 }
 802
 803 module_init(nfnl_cthelper_init);
 804 module_exit(nfnl_cthelper_exit);