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
 100         if (attr == NULL)
 101                 return -EINVAL;
 102
 103         if (help->helper->data_len == 0)
 104                 return -EINVAL;
 105
 106         nla_memcpy(help->data, nla_data(attr), sizeof(help->data));
 107         return 0;
 108 }
 109
 110 static int
 111 nfnl_cthelper_to_nlattr(struct sk_buff *skb, const struct nf_conn *ct)
 112 {
 113         const struct nf_conn_help *help = nfct_help(ct);
 114
 115         if (help->helper->data_len &&
 116             nla_put(skb, CTA_HELP_INFO, help->helper->data_len, &help->data))
 117                 goto nla_put_failure;
 118
 119         return 0;
 120
 121 nla_put_failure:
 122         return -ENOSPC;
 123 }
 124
 125 static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = {
 126         [NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING,
 127                                 .len = NF_CT_HELPER_NAME_LEN-1 },
 128         [NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, },
 129         [NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, },
 130 };
 131
 132 static int
 133 nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy,
 134                             const struct nlattr *attr)
 135 {
 136         int err;
 137         struct nlattr *tb[NFCTH_POLICY_MAX+1];
 138
 139         err = nla_parse_nested_deprecated(tb, NFCTH_POLICY_MAX, attr,
 140                                           nfnl_cthelper_expect_pol, NULL);
 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         nla_strlcpy(expect_policy->name,
 150                     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_deprecated(tb, NFCTH_POLICY_SET_MAX, attr,
 177                                           nfnl_cthelper_expect_policy_set,
 178                                           NULL);
 179         if (ret < 0)
 180                 return ret;
 181
 182         if (!tb[NFCTH_POLICY_SET_NUM])
 183                 return -EINVAL;
 184
 185         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 186         if (class_max == 0)
 187                 return -EINVAL;
 188         if (class_max > NF_CT_MAX_EXPECT_CLASSES)
 189                 return -EOVERFLOW;
 190
 191         expect_policy = kcalloc(class_max,
 192                                 sizeof(struct nf_conntrack_expect_policy),
 193                                 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         nla_strlcpy(helper->name,
 237                     tb[NFCTH_NAME], NF_CT_HELPER_NAME_LEN);
 238         size = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
 239         if (size > sizeof_field(struct nf_conn_help, data)) {
 240                 ret = -ENOMEM;
 241                 goto err2;
 242         }
 243
 244         helper->flags |= NF_CT_HELPER_F_USERSPACE;
 245         memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
 246
 247         helper->me = THIS_MODULE;
 248         helper->help = nfnl_userspace_cthelper;
 249         helper->from_nlattr = nfnl_cthelper_from_nlattr;
 250         helper->to_nlattr = nfnl_cthelper_to_nlattr;
 251
 252         /* Default to queue number zero, this can be updated at any time. */
 253         if (tb[NFCTH_QUEUE_NUM])
 254                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 255
 256         if (tb[NFCTH_STATUS]) {
 257                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 258
 259                 switch(status) {
 260                 case NFCT_HELPER_STATUS_ENABLED:
 261                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 262                         break;
 263                 case NFCT_HELPER_STATUS_DISABLED:
 264                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 265                         break;
 266                 }
 267         }
 268
 269         ret = nf_conntrack_helper_register(helper);
 270         if (ret < 0)
 271                 goto err2;
 272
 273         list_add_tail(&nfcth->list, &nfnl_cthelper_list);
 274         return 0;
 275 err2:
 276         kfree(helper->expect_policy);
 277 err1:
 278         kfree(nfcth);
 279         return ret;
 280 }
 281
 282 static int
 283 nfnl_cthelper_update_policy_one(const struct nf_conntrack_expect_policy *policy,
 284                                 struct nf_conntrack_expect_policy *new_policy,
 285                                 const struct nlattr *attr)
 286 {
 287         struct nlattr *tb[NFCTH_POLICY_MAX + 1];
 288         int err;
 289
 290         err = nla_parse_nested_deprecated(tb, NFCTH_POLICY_MAX, attr,
 291                                           nfnl_cthelper_expect_pol, NULL);
 292         if (err < 0)
 293                 return err;
 294
 295         if (!tb[NFCTH_POLICY_NAME] ||
 296             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 297             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 298                 return -EINVAL;
 299
 300         if (nla_strcmp(tb[NFCTH_POLICY_NAME], policy->name))
 301                 return -EBUSY;
 302
 303         new_policy->max_expected =
 304                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 305         if (new_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
 306                 return -EINVAL;
 307
 308         new_policy->timeout =
 309                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 310
 311         return 0;
 312 }
 313
 314 static int nfnl_cthelper_update_policy_all(struct nlattr *tb[],
 315                                            struct nf_conntrack_helper *helper)
 316 {
 317         struct nf_conntrack_expect_policy *new_policy;
 318         struct nf_conntrack_expect_policy *policy;
 319         int i, ret = 0;
 320
 321         new_policy = kmalloc_array(helper->expect_class_max + 1,
 322                                    sizeof(*new_policy), GFP_KERNEL);
 323         if (!new_policy)
 324                 return -ENOMEM;
 325
 326         /* Check first that all policy attributes are well-formed, so we don't
 327          * leave things in inconsistent state on errors.
 328          */
 329         for (i = 0; i < helper->expect_class_max + 1; i++) {
 330
 331                 if (!tb[NFCTH_POLICY_SET + i]) {
 332                         ret = -EINVAL;
 333                         goto err;
 334                 }
 335
 336                 ret = nfnl_cthelper_update_policy_one(&helper->expect_policy[i],
 337                                                       &new_policy[i],
 338                                                       tb[NFCTH_POLICY_SET + i]);
 339                 if (ret < 0)
 340                         goto err;
 341         }
 342         /* Now we can safely update them. */
 343         for (i = 0; i < helper->expect_class_max + 1; i++) {
 344                 policy = (struct nf_conntrack_expect_policy *)
 345                                 &helper->expect_policy[i];
 346                 policy->max_expected = new_policy->max_expected;
 347                 policy->timeout = new_policy->timeout;
 348         }
 349
 350 err:
 351         kfree(new_policy);
 352         return ret;
 353 }
 354
 355 static int nfnl_cthelper_update_policy(struct nf_conntrack_helper *helper,
 356                                        const struct nlattr *attr)
 357 {
 358         struct nlattr *tb[NFCTH_POLICY_SET_MAX + 1];
 359         unsigned int class_max;
 360         int err;
 361
 362         err = nla_parse_nested_deprecated(tb, NFCTH_POLICY_SET_MAX, attr,
 363                                           nfnl_cthelper_expect_policy_set,
 364                                           NULL);
 365         if (err < 0)
 366                 return err;
 367
 368         if (!tb[NFCTH_POLICY_SET_NUM])
 369                 return -EINVAL;
 370
 371         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 372         if (helper->expect_class_max + 1 != class_max)
 373                 return -EBUSY;
 374
 375         return nfnl_cthelper_update_policy_all(tb, helper);
 376 }
 377
 378 static int
 379 nfnl_cthelper_update(const struct nlattr * const tb[],
 380                      struct nf_conntrack_helper *helper)
 381 {
 382         int ret;
 383
 384         if (tb[NFCTH_PRIV_DATA_LEN])
 385                 return -EBUSY;
 386
 387         if (tb[NFCTH_POLICY]) {
 388                 ret = nfnl_cthelper_update_policy(helper, tb[NFCTH_POLICY]);
 389                 if (ret < 0)
 390                         return ret;
 391         }
 392         if (tb[NFCTH_QUEUE_NUM])
 393                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 394
 395         if (tb[NFCTH_STATUS]) {
 396                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 397
 398                 switch(status) {
 399                 case NFCT_HELPER_STATUS_ENABLED:
 400                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 401                         break;
 402                 case NFCT_HELPER_STATUS_DISABLED:
 403                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 404                         break;
 405                 }
 406         }
 407         return 0;
 408 }
 409
 410 static int nfnl_cthelper_new(struct net *net, struct sock *nfnl,
 411                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 412                              const struct nlattr * const tb[],
 413                              struct netlink_ext_ack *extack)
 414 {
 415         const char *helper_name;
 416         struct nf_conntrack_helper *cur, *helper = NULL;
 417         struct nf_conntrack_tuple tuple;
 418         struct nfnl_cthelper *nlcth;
 419         int ret = 0;
 420
 421         if (!capable(CAP_NET_ADMIN))
 422                 return -EPERM;
 423
 424         if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
 425                 return -EINVAL;
 426
 427         helper_name = nla_data(tb[NFCTH_NAME]);
 428
 429         ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 430         if (ret < 0)
 431                 return ret;
 432
 433         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 434                 cur = &nlcth->helper;
 435
 436                 if (strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 437                         continue;
 438
 439                 if ((tuple.src.l3num != cur->tuple.src.l3num ||
 440                      tuple.dst.protonum != cur->tuple.dst.protonum))
 441                         continue;
 442
 443                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 444                         return -EEXIST;
 445
 446                 helper = cur;
 447                 break;
 448         }
 449
 450         if (helper == NULL)
 451                 ret = nfnl_cthelper_create(tb, &tuple);
 452         else
 453                 ret = nfnl_cthelper_update(tb, helper);
 454
 455         return ret;
 456 }
 457
 458 static int
 459 nfnl_cthelper_dump_tuple(struct sk_buff *skb,
 460                          struct nf_conntrack_helper *helper)
 461 {
 462         struct nlattr *nest_parms;
 463
 464         nest_parms = nla_nest_start(skb, NFCTH_TUPLE);
 465         if (nest_parms == NULL)
 466                 goto nla_put_failure;
 467
 468         if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
 469                          htons(helper->tuple.src.l3num)))
 470                 goto nla_put_failure;
 471
 472         if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
 473                 goto nla_put_failure;
 474
 475         nla_nest_end(skb, nest_parms);
 476         return 0;
 477
 478 nla_put_failure:
 479         return -1;
 480 }
 481
 482 static int
 483 nfnl_cthelper_dump_policy(struct sk_buff *skb,
 484                         struct nf_conntrack_helper *helper)
 485 {
 486         int i;
 487         struct nlattr *nest_parms1, *nest_parms2;
 488
 489         nest_parms1 = nla_nest_start(skb, NFCTH_POLICY);
 490         if (nest_parms1 == NULL)
 491                 goto nla_put_failure;
 492
 493         if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
 494                          htonl(helper->expect_class_max + 1)))
 495                 goto nla_put_failure;
 496
 497         for (i = 0; i < helper->expect_class_max + 1; i++) {
 498                 nest_parms2 = nla_nest_start(skb, (NFCTH_POLICY_SET + i));
 499                 if (nest_parms2 == NULL)
 500                         goto nla_put_failure;
 501
 502                 if (nla_put_string(skb, NFCTH_POLICY_NAME,
 503                                    helper->expect_policy[i].name))
 504                         goto nla_put_failure;
 505
 506                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
 507                                  htonl(helper->expect_policy[i].max_expected)))
 508                         goto nla_put_failure;
 509
 510                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
 511                                  htonl(helper->expect_policy[i].timeout)))
 512                         goto nla_put_failure;
 513
 514                 nla_nest_end(skb, nest_parms2);
 515         }
 516         nla_nest_end(skb, nest_parms1);
 517         return 0;
 518
 519 nla_put_failure:
 520         return -1;
 521 }
 522
 523 static int
 524 nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 525                         int event, struct nf_conntrack_helper *helper)
 526 {
 527         struct nlmsghdr *nlh;
 528         struct nfgenmsg *nfmsg;
 529         unsigned int flags = portid ? NLM_F_MULTI : 0;
 530         int status;
 531
 532         event = nfnl_msg_type(NFNL_SUBSYS_CTHELPER, event);
 533         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 534         if (nlh == NULL)
 535                 goto nlmsg_failure;
 536
 537         nfmsg = nlmsg_data(nlh);
 538         nfmsg->nfgen_family = AF_UNSPEC;
 539         nfmsg->version = NFNETLINK_V0;
 540         nfmsg->res_id = 0;
 541
 542         if (nla_put_string(skb, NFCTH_NAME, helper->name))
 543                 goto nla_put_failure;
 544
 545         if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
 546                 goto nla_put_failure;
 547
 548         if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
 549                 goto nla_put_failure;
 550
 551         if (nfnl_cthelper_dump_policy(skb, helper) < 0)
 552                 goto nla_put_failure;
 553
 554         if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
 555                 goto nla_put_failure;
 556
 557         if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
 558                 status = NFCT_HELPER_STATUS_ENABLED;
 559         else
 560                 status = NFCT_HELPER_STATUS_DISABLED;
 561
 562         if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
 563                 goto nla_put_failure;
 564
 565         nlmsg_end(skb, nlh);
 566         return skb->len;
 567
 568 nlmsg_failure:
 569 nla_put_failure:
 570         nlmsg_cancel(skb, nlh);
 571         return -1;
 572 }
 573
 574 static int
 575 nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
 576 {
 577         struct nf_conntrack_helper *cur, *last;
 578
 579         rcu_read_lock();
 580         last = (struct nf_conntrack_helper *)cb->args[1];
 581         for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
 582 restart:
 583                 hlist_for_each_entry_rcu(cur,
 584                                 &nf_ct_helper_hash[cb->args[0]], hnode) {
 585
 586                         /* skip non-userspace conntrack helpers. */
 587                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 588                                 continue;
 589
 590                         if (cb->args[1]) {
 591                                 if (cur != last)
 592                                         continue;
 593                                 cb->args[1] = 0;
 594                         }
 595                         if (nfnl_cthelper_fill_info(skb,
 596                                             NETLINK_CB(cb->skb).portid,
 597                                             cb->nlh->nlmsg_seq,
 598                                             NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 599                                             NFNL_MSG_CTHELPER_NEW, cur) < 0) {
 600                                 cb->args[1] = (unsigned long)cur;
 601                                 goto out;
 602                         }
 603                 }
 604         }
 605         if (cb->args[1]) {
 606                 cb->args[1] = 0;
 607                 goto restart;
 608         }
 609 out:
 610         rcu_read_unlock();
 611         return skb->len;
 612 }
 613
 614 static int nfnl_cthelper_get(struct net *net, struct sock *nfnl,
 615                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 616                              const struct nlattr * const tb[],
 617                              struct netlink_ext_ack *extack)
 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 (nlh->nlmsg_flags & NLM_F_DUMP) {
 631                 struct netlink_dump_control c = {
 632                         .dump = nfnl_cthelper_dump_table,
 633                 };
 634                 return netlink_dump_start(nfnl, skb, 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                                               nlh->nlmsg_seq,
 667                                               NFNL_MSG_TYPE(nlh->nlmsg_type),
 668                                               NFNL_MSG_CTHELPER_NEW, cur);
 669                 if (ret <= 0) {
 670                         kfree_skb(skb2);
 671                         break;
 672                 }
 673
 674                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 675                                       MSG_DONTWAIT);
 676                 if (ret > 0)
 677                         ret = 0;
 678
 679                 /* this avoids a loop in nfnetlink. */
 680                 return ret == -EAGAIN ? -ENOBUFS : ret;
 681         }
 682         return ret;
 683 }
 684
 685 static int nfnl_cthelper_del(struct net *net, struct sock *nfnl,
 686                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 687                              const struct nlattr * const tb[],
 688                              struct netlink_ext_ack *extack)
 689 {
 690         char *helper_name = NULL;
 691         struct nf_conntrack_helper *cur;
 692         struct nf_conntrack_tuple tuple;
 693         bool tuple_set = false, found = false;
 694         struct nfnl_cthelper *nlcth, *n;
 695         int j = 0, ret;
 696
 697         if (!capable(CAP_NET_ADMIN))
 698                 return -EPERM;
 699
 700         if (tb[NFCTH_NAME])
 701                 helper_name = nla_data(tb[NFCTH_NAME]);
 702
 703         if (tb[NFCTH_TUPLE]) {
 704                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 705                 if (ret < 0)
 706                         return ret;
 707
 708                 tuple_set = true;
 709         }
 710
 711         ret = -ENOENT;
 712         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 713                 cur = &nlcth->helper;
 714                 j++;
 715
 716                 if (helper_name &&
 717                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 718                         continue;
 719
 720                 if (tuple_set &&
 721                     (tuple.src.l3num != cur->tuple.src.l3num ||
 722                      tuple.dst.protonum != cur->tuple.dst.protonum))
 723                         continue;
 724
 725                 if (refcount_dec_if_one(&cur->refcnt)) {
 726                         found = true;
 727                         nf_conntrack_helper_unregister(cur);
 728                         kfree(cur->expect_policy);
 729
 730                         list_del(&nlcth->list);
 731                         kfree(nlcth);
 732                 } else {
 733                         ret = -EBUSY;
 734                 }
 735         }
 736
 737         /* Make sure we return success if we flush and there is no helpers */
 738         return (found || j == 0) ? 0 : ret;
 739 }
 740
 741 static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
 742         [NFCTH_NAME] = { .type = NLA_NUL_STRING,
 743                          .len = NF_CT_HELPER_NAME_LEN-1 },
 744         [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
 745         [NFCTH_PRIV_DATA_LEN] = { .type = NLA_U32, },
 746         [NFCTH_STATUS] = { .type = NLA_U32, },
 747 };
 748
 749 static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
 750         [NFNL_MSG_CTHELPER_NEW]         = { .call = nfnl_cthelper_new,
 751                                             .attr_count = NFCTH_MAX,
 752                                             .policy = nfnl_cthelper_policy },
 753         [NFNL_MSG_CTHELPER_GET]         = { .call = nfnl_cthelper_get,
 754                                             .attr_count = NFCTH_MAX,
 755                                             .policy = nfnl_cthelper_policy },
 756         [NFNL_MSG_CTHELPER_DEL]         = { .call = nfnl_cthelper_del,
 757                                             .attr_count = NFCTH_MAX,
 758                                             .policy = nfnl_cthelper_policy },
 759 };
 760
 761 static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
 762         .name                           = "cthelper",
 763         .subsys_id                      = NFNL_SUBSYS_CTHELPER,
 764         .cb_count                       = NFNL_MSG_CTHELPER_MAX,
 765         .cb                             = nfnl_cthelper_cb,
 766 };
 767
 768 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
 769
 770 static int __init nfnl_cthelper_init(void)
 771 {
 772         int ret;
 773
 774         ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
 775         if (ret < 0) {
 776                 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
 777                 goto err_out;
 778         }
 779         return 0;
 780 err_out:
 781         return ret;
 782 }
 783
 784 static void __exit nfnl_cthelper_exit(void)
 785 {
 786         struct nf_conntrack_helper *cur;
 787         struct nfnl_cthelper *nlcth, *n;
 788
 789         nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
 790
 791         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 792                 cur = &nlcth->helper;
 793
 794                 nf_conntrack_helper_unregister(cur);
 795                 kfree(cur->expect_policy);
 796                 kfree(nlcth);
 797         }
 798 }
 799
 800 module_init(nfnl_cthelper_init);
 801 module_exit(nfnl_cthelper_exit);