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 <linux/capability.h>
  21 #include <net/netlink.h>
  22 #include <net/sock.h>
  23
  24 #include <net/netfilter/nf_conntrack_helper.h>
  25 #include <net/netfilter/nf_conntrack_expect.h>
  26 #include <net/netfilter/nf_conntrack_ecache.h>
  27
  28 #include <linux/netfilter/nfnetlink.h>
  29 #include <linux/netfilter/nfnetlink_conntrack.h>
  30 #include <linux/netfilter/nfnetlink_cthelper.h>
  31
  32 MODULE_LICENSE("GPL");
  33 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
  34 MODULE_DESCRIPTION("nfnl_cthelper: User-space connection tracking helpers");
  35
  36 struct nfnl_cthelper {
  37         struct list_head                list;
  38         struct nf_conntrack_helper      helper;
  39 };
  40
  41 static LIST_HEAD(nfnl_cthelper_list);
  42
  43 static int
  44 nfnl_userspace_cthelper(struct sk_buff *skb, unsigned int protoff,
  45                         struct nf_conn *ct, enum ip_conntrack_info ctinfo)
  46 {
  47         const struct nf_conn_help *help;
  48         struct nf_conntrack_helper *helper;
  49
  50         help = nfct_help(ct);
  51         if (help == NULL)
  52                 return NF_DROP;
  53
  54         /* rcu_read_lock()ed by nf_hook_thresh */
  55         helper = rcu_dereference(help->helper);
  56         if (helper == NULL)
  57                 return NF_DROP;
  58
  59         /* This is a user-space helper not yet configured, skip. */
  60         if ((helper->flags &
  61             (NF_CT_HELPER_F_USERSPACE | NF_CT_HELPER_F_CONFIGURED)) ==
  62              NF_CT_HELPER_F_USERSPACE)
  63                 return NF_ACCEPT;
  64
  65         /* If the user-space helper is not available, don't block traffic. */
  66         return NF_QUEUE_NR(helper->queue_num) | NF_VERDICT_FLAG_QUEUE_BYPASS;
  67 }
  68
  69 static const struct nla_policy nfnl_cthelper_tuple_pol[NFCTH_TUPLE_MAX+1] = {
  70         [NFCTH_TUPLE_L3PROTONUM] = { .type = NLA_U16, },
  71         [NFCTH_TUPLE_L4PROTONUM] = { .type = NLA_U8, },
  72 };
  73
  74 static int
  75 nfnl_cthelper_parse_tuple(struct nf_conntrack_tuple *tuple,
  76                           const struct nlattr *attr)
  77 {
  78         int err;
  79         struct nlattr *tb[NFCTH_TUPLE_MAX+1];
  80
  81         err = nla_parse_nested(tb, NFCTH_TUPLE_MAX, attr,
  82                                nfnl_cthelper_tuple_pol, NULL);
  83         if (err < 0)
  84                 return err;
  85
  86         if (!tb[NFCTH_TUPLE_L3PROTONUM] || !tb[NFCTH_TUPLE_L4PROTONUM])
  87                 return -EINVAL;
  88
  89         /* Not all fields are initialized so first zero the tuple */
  90         memset(tuple, 0, sizeof(struct nf_conntrack_tuple));
  91
  92         tuple->src.l3num = ntohs(nla_get_be16(tb[NFCTH_TUPLE_L3PROTONUM]));
  93         tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]);
  94
  95         return 0;
  96 }
  97
  98 static int
  99 nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
 100 {
 101         struct nf_conn_help *help = nfct_help(ct);
 102
 103         if (attr == NULL)
 104                 return -EINVAL;
 105
 106         if (help->helper->data_len == 0)
 107                 return -EINVAL;
 108
 109         nla_memcpy(help->data, attr, sizeof(help->data));
 110         return 0;
 111 }
 112
 113 static int
 114 nfnl_cthelper_to_nlattr(struct sk_buff *skb, const struct nf_conn *ct)
 115 {
 116         const struct nf_conn_help *help = nfct_help(ct);
 117
 118         if (help->helper->data_len &&
 119             nla_put(skb, CTA_HELP_INFO, help->helper->data_len, &help->data))
 120                 goto nla_put_failure;
 121
 122         return 0;
 123
 124 nla_put_failure:
 125         return -ENOSPC;
 126 }
 127
 128 static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = {
 129         [NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING,
 130                                 .len = NF_CT_HELPER_NAME_LEN-1 },
 131         [NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, },
 132         [NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, },
 133 };
 134
 135 static int
 136 nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy,
 137                             const struct nlattr *attr)
 138 {
 139         int err;
 140         struct nlattr *tb[NFCTH_POLICY_MAX+1];
 141
 142         err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr,
 143                                nfnl_cthelper_expect_pol, NULL);
 144         if (err < 0)
 145                 return err;
 146
 147         if (!tb[NFCTH_POLICY_NAME] ||
 148             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 149             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 150                 return -EINVAL;
 151
 152         nla_strlcpy(expect_policy->name,
 153                     tb[NFCTH_POLICY_NAME], NF_CT_HELPER_NAME_LEN);
 154         expect_policy->max_expected =
 155                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 156         if (expect_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
 157                 return -EINVAL;
 158
 159         expect_policy->timeout =
 160                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 161
 162         return 0;
 163 }
 164
 165 static const struct nla_policy
 166 nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
 167         [NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, },
 168 };
 169
 170 static int
 171 nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper,
 172                                   const struct nlattr *attr)
 173 {
 174         int i, ret;
 175         struct nf_conntrack_expect_policy *expect_policy;
 176         struct nlattr *tb[NFCTH_POLICY_SET_MAX+1];
 177         unsigned int class_max;
 178
 179         ret = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
 180                                nfnl_cthelper_expect_policy_set, NULL);
 181         if (ret < 0)
 182                 return ret;
 183
 184         if (!tb[NFCTH_POLICY_SET_NUM])
 185                 return -EINVAL;
 186
 187         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 188         if (class_max == 0)
 189                 return -EINVAL;
 190         if (class_max > NF_CT_MAX_EXPECT_CLASSES)
 191                 return -EOVERFLOW;
 192
 193         expect_policy = kcalloc(class_max,
 194                                 sizeof(struct nf_conntrack_expect_policy),
 195                                 GFP_KERNEL);
 196         if (expect_policy == NULL)
 197                 return -ENOMEM;
 198
 199         for (i = 0; i < class_max; i++) {
 200                 if (!tb[NFCTH_POLICY_SET+i])
 201                         goto err;
 202
 203                 ret = nfnl_cthelper_expect_policy(&expect_policy[i],
 204                                                   tb[NFCTH_POLICY_SET+i]);
 205                 if (ret < 0)
 206                         goto err;
 207         }
 208
 209         helper->expect_class_max = class_max - 1;
 210         helper->expect_policy = expect_policy;
 211         return 0;
 212 err:
 213         kfree(expect_policy);
 214         return -EINVAL;
 215 }
 216
 217 static int
 218 nfnl_cthelper_create(const struct nlattr * const tb[],
 219                      struct nf_conntrack_tuple *tuple)
 220 {
 221         struct nf_conntrack_helper *helper;
 222         struct nfnl_cthelper *nfcth;
 223         unsigned int size;
 224         int ret;
 225
 226         if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
 227                 return -EINVAL;
 228
 229         nfcth = kzalloc(sizeof(*nfcth), GFP_KERNEL);
 230         if (nfcth == NULL)
 231                 return -ENOMEM;
 232         helper = &nfcth->helper;
 233
 234         ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
 235         if (ret < 0)
 236                 goto err1;
 237
 238         nla_strlcpy(helper->name,
 239                     tb[NFCTH_NAME], NF_CT_HELPER_NAME_LEN);
 240         size = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
 241         if (size > FIELD_SIZEOF(struct nf_conn_help, data)) {
 242                 ret = -ENOMEM;
 243                 goto err2;
 244         }
 245         helper->data_len = size;
 246
 247         helper->flags |= NF_CT_HELPER_F_USERSPACE;
 248         memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
 249
 250         helper->me = THIS_MODULE;
 251         helper->help = nfnl_userspace_cthelper;
 252         helper->from_nlattr = nfnl_cthelper_from_nlattr;
 253         helper->to_nlattr = nfnl_cthelper_to_nlattr;
 254
 255         /* Default to queue number zero, this can be updated at any time. */
 256         if (tb[NFCTH_QUEUE_NUM])
 257                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 258
 259         if (tb[NFCTH_STATUS]) {
 260                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 261
 262                 switch(status) {
 263                 case NFCT_HELPER_STATUS_ENABLED:
 264                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 265                         break;
 266                 case NFCT_HELPER_STATUS_DISABLED:
 267                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 268                         break;
 269                 }
 270         }
 271
 272         ret = nf_conntrack_helper_register(helper);
 273         if (ret < 0)
 274                 goto err2;
 275
 276         list_add_tail(&nfcth->list, &nfnl_cthelper_list);
 277         return 0;
 278 err2:
 279         kfree(helper->expect_policy);
 280 err1:
 281         kfree(nfcth);
 282         return ret;
 283 }
 284
 285 static int
 286 nfnl_cthelper_update_policy_one(const struct nf_conntrack_expect_policy *policy,
 287                                 struct nf_conntrack_expect_policy *new_policy,
 288                                 const struct nlattr *attr)
 289 {
 290         struct nlattr *tb[NFCTH_POLICY_MAX + 1];
 291         int err;
 292
 293         err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr,
 294                                nfnl_cthelper_expect_pol, NULL);
 295         if (err < 0)
 296                 return err;
 297
 298         if (!tb[NFCTH_POLICY_NAME] ||
 299             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 300             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 301                 return -EINVAL;
 302
 303         if (nla_strcmp(tb[NFCTH_POLICY_NAME], policy->name))
 304                 return -EBUSY;
 305
 306         new_policy->max_expected =
 307                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 308         if (new_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
 309                 return -EINVAL;
 310
 311         new_policy->timeout =
 312                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 313
 314         return 0;
 315 }
 316
 317 static int nfnl_cthelper_update_policy_all(struct nlattr *tb[],
 318                                            struct nf_conntrack_helper *helper)
 319 {
 320         struct nf_conntrack_expect_policy *new_policy;
 321         struct nf_conntrack_expect_policy *policy;
 322         int i, ret = 0;
 323
 324         new_policy = kmalloc_array(helper->expect_class_max + 1,
 325                                    sizeof(*new_policy), GFP_KERNEL);
 326         if (!new_policy)
 327                 return -ENOMEM;
 328
 329         /* Check first that all policy attributes are well-formed, so we don't
 330          * leave things in inconsistent state on errors.
 331          */
 332         for (i = 0; i < helper->expect_class_max + 1; i++) {
 333
 334                 if (!tb[NFCTH_POLICY_SET + i]) {
 335                         ret = -EINVAL;
 336                         goto err;
 337                 }
 338
 339                 ret = nfnl_cthelper_update_policy_one(&helper->expect_policy[i],
 340                                                       &new_policy[i],
 341                                                       tb[NFCTH_POLICY_SET + i]);
 342                 if (ret < 0)
 343                         goto err;
 344         }
 345         /* Now we can safely update them. */
 346         for (i = 0; i < helper->expect_class_max + 1; i++) {
 347                 policy = (struct nf_conntrack_expect_policy *)
 348                                 &helper->expect_policy[i];
 349                 policy->max_expected = new_policy->max_expected;
 350                 policy->timeout = new_policy->timeout;
 351         }
 352
 353 err:
 354         kfree(new_policy);
 355         return ret;
 356 }
 357
 358 static int nfnl_cthelper_update_policy(struct nf_conntrack_helper *helper,
 359                                        const struct nlattr *attr)
 360 {
 361         struct nlattr *tb[NFCTH_POLICY_SET_MAX + 1];
 362         unsigned int class_max;
 363         int err;
 364
 365         err = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
 366                                nfnl_cthelper_expect_policy_set, NULL);
 367         if (err < 0)
 368                 return err;
 369
 370         if (!tb[NFCTH_POLICY_SET_NUM])
 371                 return -EINVAL;
 372
 373         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 374         if (helper->expect_class_max + 1 != class_max)
 375                 return -EBUSY;
 376
 377         return nfnl_cthelper_update_policy_all(tb, helper);
 378 }
 379
 380 static int
 381 nfnl_cthelper_update(const struct nlattr * const tb[],
 382                      struct nf_conntrack_helper *helper)
 383 {
 384         int ret;
 385
 386         if (tb[NFCTH_PRIV_DATA_LEN])
 387                 return -EBUSY;
 388
 389         if (tb[NFCTH_POLICY]) {
 390                 ret = nfnl_cthelper_update_policy(helper, tb[NFCTH_POLICY]);
 391                 if (ret < 0)
 392                         return ret;
 393         }
 394         if (tb[NFCTH_QUEUE_NUM])
 395                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 396
 397         if (tb[NFCTH_STATUS]) {
 398                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 399
 400                 switch(status) {
 401                 case NFCT_HELPER_STATUS_ENABLED:
 402                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 403                         break;
 404                 case NFCT_HELPER_STATUS_DISABLED:
 405                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 406                         break;
 407                 }
 408         }
 409         return 0;
 410 }
 411
 412 static int nfnl_cthelper_new(struct net *net, struct sock *nfnl,
 413                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 414                              const struct nlattr * const tb[],
 415                              struct netlink_ext_ack *extack)
 416 {
 417         const char *helper_name;
 418         struct nf_conntrack_helper *cur, *helper = NULL;
 419         struct nf_conntrack_tuple tuple;
 420         struct nfnl_cthelper *nlcth;
 421         int ret = 0;
 422
 423         if (!capable(CAP_NET_ADMIN))
 424                 return -EPERM;
 425
 426         if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
 427                 return -EINVAL;
 428
 429         helper_name = nla_data(tb[NFCTH_NAME]);
 430
 431         ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 432         if (ret < 0)
 433                 return ret;
 434
 435         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 436                 cur = &nlcth->helper;
 437
 438                 if (strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 439                         continue;
 440
 441                 if ((tuple.src.l3num != cur->tuple.src.l3num ||
 442                      tuple.dst.protonum != cur->tuple.dst.protonum))
 443                         continue;
 444
 445                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 446                         return -EEXIST;
 447
 448                 helper = cur;
 449                 break;
 450         }
 451
 452         if (helper == NULL)
 453                 ret = nfnl_cthelper_create(tb, &tuple);
 454         else
 455                 ret = nfnl_cthelper_update(tb, helper);
 456
 457         return ret;
 458 }
 459
 460 static int
 461 nfnl_cthelper_dump_tuple(struct sk_buff *skb,
 462                          struct nf_conntrack_helper *helper)
 463 {
 464         struct nlattr *nest_parms;
 465
 466         nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
 467         if (nest_parms == NULL)
 468                 goto nla_put_failure;
 469
 470         if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
 471                          htons(helper->tuple.src.l3num)))
 472                 goto nla_put_failure;
 473
 474         if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
 475                 goto nla_put_failure;
 476
 477         nla_nest_end(skb, nest_parms);
 478         return 0;
 479
 480 nla_put_failure:
 481         return -1;
 482 }
 483
 484 static int
 485 nfnl_cthelper_dump_policy(struct sk_buff *skb,
 486                         struct nf_conntrack_helper *helper)
 487 {
 488         int i;
 489         struct nlattr *nest_parms1, *nest_parms2;
 490
 491         nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
 492         if (nest_parms1 == NULL)
 493                 goto nla_put_failure;
 494
 495         if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
 496                          htonl(helper->expect_class_max + 1)))
 497                 goto nla_put_failure;
 498
 499         for (i = 0; i < helper->expect_class_max + 1; i++) {
 500                 nest_parms2 = nla_nest_start(skb,
 501                                 (NFCTH_POLICY_SET+i) | NLA_F_NESTED);
 502                 if (nest_parms2 == NULL)
 503                         goto nla_put_failure;
 504
 505                 if (nla_put_string(skb, NFCTH_POLICY_NAME,
 506                                    helper->expect_policy[i].name))
 507                         goto nla_put_failure;
 508
 509                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
 510                                  htonl(helper->expect_policy[i].max_expected)))
 511                         goto nla_put_failure;
 512
 513                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
 514                                  htonl(helper->expect_policy[i].timeout)))
 515                         goto nla_put_failure;
 516
 517                 nla_nest_end(skb, nest_parms2);
 518         }
 519         nla_nest_end(skb, nest_parms1);
 520         return 0;
 521
 522 nla_put_failure:
 523         return -1;
 524 }
 525
 526 static int
 527 nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 528                         int event, struct nf_conntrack_helper *helper)
 529 {
 530         struct nlmsghdr *nlh;
 531         struct nfgenmsg *nfmsg;
 532         unsigned int flags = portid ? NLM_F_MULTI : 0;
 533         int status;
 534
 535         event = nfnl_msg_type(NFNL_SUBSYS_CTHELPER, event);
 536         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 537         if (nlh == NULL)
 538                 goto nlmsg_failure;
 539
 540         nfmsg = nlmsg_data(nlh);
 541         nfmsg->nfgen_family = AF_UNSPEC;
 542         nfmsg->version = NFNETLINK_V0;
 543         nfmsg->res_id = 0;
 544
 545         if (nla_put_string(skb, NFCTH_NAME, helper->name))
 546                 goto nla_put_failure;
 547
 548         if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
 549                 goto nla_put_failure;
 550
 551         if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
 552                 goto nla_put_failure;
 553
 554         if (nfnl_cthelper_dump_policy(skb, helper) < 0)
 555                 goto nla_put_failure;
 556
 557         if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
 558                 goto nla_put_failure;
 559
 560         if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
 561                 status = NFCT_HELPER_STATUS_ENABLED;
 562         else
 563                 status = NFCT_HELPER_STATUS_DISABLED;
 564
 565         if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
 566                 goto nla_put_failure;
 567
 568         nlmsg_end(skb, nlh);
 569         return skb->len;
 570
 571 nlmsg_failure:
 572 nla_put_failure:
 573         nlmsg_cancel(skb, nlh);
 574         return -1;
 575 }
 576
 577 static int
 578 nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
 579 {
 580         struct nf_conntrack_helper *cur, *last;
 581
 582         rcu_read_lock();
 583         last = (struct nf_conntrack_helper *)cb->args[1];
 584         for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
 585 restart:
 586                 hlist_for_each_entry_rcu(cur,
 587                                 &nf_ct_helper_hash[cb->args[0]], hnode) {
 588
 589                         /* skip non-userspace conntrack helpers. */
 590                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 591                                 continue;
 592
 593                         if (cb->args[1]) {
 594                                 if (cur != last)
 595                                         continue;
 596                                 cb->args[1] = 0;
 597                         }
 598                         if (nfnl_cthelper_fill_info(skb,
 599                                             NETLINK_CB(cb->skb).portid,
 600                                             cb->nlh->nlmsg_seq,
 601                                             NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 602                                             NFNL_MSG_CTHELPER_NEW, cur) < 0) {
 603                                 cb->args[1] = (unsigned long)cur;
 604                                 goto out;
 605                         }
 606                 }
 607         }
 608         if (cb->args[1]) {
 609                 cb->args[1] = 0;
 610                 goto restart;
 611         }
 612 out:
 613         rcu_read_unlock();
 614         return skb->len;
 615 }
 616
 617 static int nfnl_cthelper_get(struct net *net, struct sock *nfnl,
 618                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 619                              const struct nlattr * const tb[],
 620                              struct netlink_ext_ack *extack)
 621 {
 622         int ret = -ENOENT;
 623         struct nf_conntrack_helper *cur;
 624         struct sk_buff *skb2;
 625         char *helper_name = NULL;
 626         struct nf_conntrack_tuple tuple;
 627         struct nfnl_cthelper *nlcth;
 628         bool tuple_set = false;
 629
 630         if (!capable(CAP_NET_ADMIN))
 631                 return -EPERM;
 632
 633         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 634                 struct netlink_dump_control c = {
 635                         .dump = nfnl_cthelper_dump_table,
 636                 };
 637                 return netlink_dump_start(nfnl, skb, nlh, &c);
 638         }
 639
 640         if (tb[NFCTH_NAME])
 641                 helper_name = nla_data(tb[NFCTH_NAME]);
 642
 643         if (tb[NFCTH_TUPLE]) {
 644                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 645                 if (ret < 0)
 646                         return ret;
 647
 648                 tuple_set = true;
 649         }
 650
 651         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 652                 cur = &nlcth->helper;
 653                 if (helper_name &&
 654                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 655                         continue;
 656
 657                 if (tuple_set &&
 658                     (tuple.src.l3num != cur->tuple.src.l3num ||
 659                      tuple.dst.protonum != cur->tuple.dst.protonum))
 660                         continue;
 661
 662                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 663                 if (skb2 == NULL) {
 664                         ret = -ENOMEM;
 665                         break;
 666                 }
 667
 668                 ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
 669                                               nlh->nlmsg_seq,
 670                                               NFNL_MSG_TYPE(nlh->nlmsg_type),
 671                                               NFNL_MSG_CTHELPER_NEW, cur);
 672                 if (ret <= 0) {
 673                         kfree_skb(skb2);
 674                         break;
 675                 }
 676
 677                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 678                                       MSG_DONTWAIT);
 679                 if (ret > 0)
 680                         ret = 0;
 681
 682                 /* this avoids a loop in nfnetlink. */
 683                 return ret == -EAGAIN ? -ENOBUFS : ret;
 684         }
 685         return ret;
 686 }
 687
 688 static int nfnl_cthelper_del(struct net *net, struct sock *nfnl,
 689                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 690                              const struct nlattr * const tb[],
 691                              struct netlink_ext_ack *extack)
 692 {
 693         char *helper_name = NULL;
 694         struct nf_conntrack_helper *cur;
 695         struct nf_conntrack_tuple tuple;
 696         bool tuple_set = false, found = false;
 697         struct nfnl_cthelper *nlcth, *n;
 698         int j = 0, ret;
 699
 700         if (!capable(CAP_NET_ADMIN))
 701                 return -EPERM;
 702
 703         if (tb[NFCTH_NAME])
 704                 helper_name = nla_data(tb[NFCTH_NAME]);
 705
 706         if (tb[NFCTH_TUPLE]) {
 707                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 708                 if (ret < 0)
 709                         return ret;
 710
 711                 tuple_set = true;
 712         }
 713
 714         ret = -ENOENT;
 715         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 716                 cur = &nlcth->helper;
 717                 j++;
 718
 719                 if (helper_name &&
 720                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 721                         continue;
 722
 723                 if (tuple_set &&
 724                     (tuple.src.l3num != cur->tuple.src.l3num ||
 725                      tuple.dst.protonum != cur->tuple.dst.protonum))
 726                         continue;
 727
 728                 if (refcount_dec_if_one(&cur->refcnt)) {
 729                         found = true;
 730                         nf_conntrack_helper_unregister(cur);
 731                         kfree(cur->expect_policy);
 732
 733                         list_del(&nlcth->list);
 734                         kfree(nlcth);
 735                 } else {
 736                         ret = -EBUSY;
 737                 }
 738         }
 739
 740         /* Make sure we return success if we flush and there is no helpers */
 741         return (found || j == 0) ? 0 : ret;
 742 }
 743
 744 static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
 745         [NFCTH_NAME] = { .type = NLA_NUL_STRING,
 746                          .len = NF_CT_HELPER_NAME_LEN-1 },
 747         [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
 748         [NFCTH_PRIV_DATA_LEN] = { .type = NLA_U32, },
 749         [NFCTH_STATUS] = { .type = NLA_U32, },
 750 };
 751
 752 static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
 753         [NFNL_MSG_CTHELPER_NEW]         = { .call = nfnl_cthelper_new,
 754                                             .attr_count = NFCTH_MAX,
 755                                             .policy = nfnl_cthelper_policy },
 756         [NFNL_MSG_CTHELPER_GET]         = { .call = nfnl_cthelper_get,
 757                                             .attr_count = NFCTH_MAX,
 758                                             .policy = nfnl_cthelper_policy },
 759         [NFNL_MSG_CTHELPER_DEL]         = { .call = nfnl_cthelper_del,
 760                                             .attr_count = NFCTH_MAX,
 761                                             .policy = nfnl_cthelper_policy },
 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);