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, nla_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
 246         helper->flags |= NF_CT_HELPER_F_USERSPACE;
 247         memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
 248
 249         helper->me = THIS_MODULE;
 250         helper->help = nfnl_userspace_cthelper;
 251         helper->from_nlattr = nfnl_cthelper_from_nlattr;
 252         helper->to_nlattr = nfnl_cthelper_to_nlattr;
 253
 254         /* Default to queue number zero, this can be updated at any time. */
 255         if (tb[NFCTH_QUEUE_NUM])
 256                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 257
 258         if (tb[NFCTH_STATUS]) {
 259                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 260
 261                 switch(status) {
 262                 case NFCT_HELPER_STATUS_ENABLED:
 263                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 264                         break;
 265                 case NFCT_HELPER_STATUS_DISABLED:
 266                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 267                         break;
 268                 }
 269         }
 270
 271         ret = nf_conntrack_helper_register(helper);
 272         if (ret < 0)
 273                 goto err2;
 274
 275         list_add_tail(&nfcth->list, &nfnl_cthelper_list);
 276         return 0;
 277 err2:
 278         kfree(helper->expect_policy);
 279 err1:
 280         kfree(nfcth);
 281         return ret;
 282 }
 283
 284 static int
 285 nfnl_cthelper_update_policy_one(const struct nf_conntrack_expect_policy *policy,
 286                                 struct nf_conntrack_expect_policy *new_policy,
 287                                 const struct nlattr *attr)
 288 {
 289         struct nlattr *tb[NFCTH_POLICY_MAX + 1];
 290         int err;
 291
 292         err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr,
 293                                nfnl_cthelper_expect_pol, NULL);
 294         if (err < 0)
 295                 return err;
 296
 297         if (!tb[NFCTH_POLICY_NAME] ||
 298             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 299             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 300                 return -EINVAL;
 301
 302         if (nla_strcmp(tb[NFCTH_POLICY_NAME], policy->name))
 303                 return -EBUSY;
 304
 305         new_policy->max_expected =
 306                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 307         if (new_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
 308                 return -EINVAL;
 309
 310         new_policy->timeout =
 311                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 312
 313         return 0;
 314 }
 315
 316 static int nfnl_cthelper_update_policy_all(struct nlattr *tb[],
 317                                            struct nf_conntrack_helper *helper)
 318 {
 319         struct nf_conntrack_expect_policy *new_policy;
 320         struct nf_conntrack_expect_policy *policy;
 321         int i, ret = 0;
 322
 323         new_policy = kmalloc_array(helper->expect_class_max + 1,
 324                                    sizeof(*new_policy), GFP_KERNEL);
 325         if (!new_policy)
 326                 return -ENOMEM;
 327
 328         /* Check first that all policy attributes are well-formed, so we don't
 329          * leave things in inconsistent state on errors.
 330          */
 331         for (i = 0; i < helper->expect_class_max + 1; i++) {
 332
 333                 if (!tb[NFCTH_POLICY_SET + i]) {
 334                         ret = -EINVAL;
 335                         goto err;
 336                 }
 337
 338                 ret = nfnl_cthelper_update_policy_one(&helper->expect_policy[i],
 339                                                       &new_policy[i],
 340                                                       tb[NFCTH_POLICY_SET + i]);
 341                 if (ret < 0)
 342                         goto err;
 343         }
 344         /* Now we can safely update them. */
 345         for (i = 0; i < helper->expect_class_max + 1; i++) {
 346                 policy = (struct nf_conntrack_expect_policy *)
 347                                 &helper->expect_policy[i];
 348                 policy->max_expected = new_policy->max_expected;
 349                 policy->timeout = new_policy->timeout;
 350         }
 351
 352 err:
 353         kfree(new_policy);
 354         return ret;
 355 }
 356
 357 static int nfnl_cthelper_update_policy(struct nf_conntrack_helper *helper,
 358                                        const struct nlattr *attr)
 359 {
 360         struct nlattr *tb[NFCTH_POLICY_SET_MAX + 1];
 361         unsigned int class_max;
 362         int err;
 363
 364         err = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
 365                                nfnl_cthelper_expect_policy_set, NULL);
 366         if (err < 0)
 367                 return err;
 368
 369         if (!tb[NFCTH_POLICY_SET_NUM])
 370                 return -EINVAL;
 371
 372         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 373         if (helper->expect_class_max + 1 != class_max)
 374                 return -EBUSY;
 375
 376         return nfnl_cthelper_update_policy_all(tb, helper);
 377 }
 378
 379 static int
 380 nfnl_cthelper_update(const struct nlattr * const tb[],
 381                      struct nf_conntrack_helper *helper)
 382 {
 383         int ret;
 384
 385         if (tb[NFCTH_PRIV_DATA_LEN])
 386                 return -EBUSY;
 387
 388         if (tb[NFCTH_POLICY]) {
 389                 ret = nfnl_cthelper_update_policy(helper, tb[NFCTH_POLICY]);
 390                 if (ret < 0)
 391                         return ret;
 392         }
 393         if (tb[NFCTH_QUEUE_NUM])
 394                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 395
 396         if (tb[NFCTH_STATUS]) {
 397                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 398
 399                 switch(status) {
 400                 case NFCT_HELPER_STATUS_ENABLED:
 401                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 402                         break;
 403                 case NFCT_HELPER_STATUS_DISABLED:
 404                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 405                         break;
 406                 }
 407         }
 408         return 0;
 409 }
 410
 411 static int nfnl_cthelper_new(struct net *net, struct sock *nfnl,
 412                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 413                              const struct nlattr * const tb[],
 414                              struct netlink_ext_ack *extack)
 415 {
 416         const char *helper_name;
 417         struct nf_conntrack_helper *cur, *helper = NULL;
 418         struct nf_conntrack_tuple tuple;
 419         struct nfnl_cthelper *nlcth;
 420         int ret = 0;
 421
 422         if (!capable(CAP_NET_ADMIN))
 423                 return -EPERM;
 424
 425         if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
 426                 return -EINVAL;
 427
 428         helper_name = nla_data(tb[NFCTH_NAME]);
 429
 430         ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 431         if (ret < 0)
 432                 return ret;
 433
 434         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 435                 cur = &nlcth->helper;
 436
 437                 if (strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 438                         continue;
 439
 440                 if ((tuple.src.l3num != cur->tuple.src.l3num ||
 441                      tuple.dst.protonum != cur->tuple.dst.protonum))
 442                         continue;
 443
 444                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 445                         return -EEXIST;
 446
 447                 helper = cur;
 448                 break;
 449         }
 450
 451         if (helper == NULL)
 452                 ret = nfnl_cthelper_create(tb, &tuple);
 453         else
 454                 ret = nfnl_cthelper_update(tb, helper);
 455
 456         return ret;
 457 }
 458
 459 static int
 460 nfnl_cthelper_dump_tuple(struct sk_buff *skb,
 461                          struct nf_conntrack_helper *helper)
 462 {
 463         struct nlattr *nest_parms;
 464
 465         nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
 466         if (nest_parms == NULL)
 467                 goto nla_put_failure;
 468
 469         if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
 470                          htons(helper->tuple.src.l3num)))
 471                 goto nla_put_failure;
 472
 473         if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
 474                 goto nla_put_failure;
 475
 476         nla_nest_end(skb, nest_parms);
 477         return 0;
 478
 479 nla_put_failure:
 480         return -1;
 481 }
 482
 483 static int
 484 nfnl_cthelper_dump_policy(struct sk_buff *skb,
 485                         struct nf_conntrack_helper *helper)
 486 {
 487         int i;
 488         struct nlattr *nest_parms1, *nest_parms2;
 489
 490         nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
 491         if (nest_parms1 == NULL)
 492                 goto nla_put_failure;
 493
 494         if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
 495                          htonl(helper->expect_class_max + 1)))
 496                 goto nla_put_failure;
 497
 498         for (i = 0; i < helper->expect_class_max + 1; i++) {
 499                 nest_parms2 = nla_nest_start(skb,
 500                                 (NFCTH_POLICY_SET+i) | NLA_F_NESTED);
 501                 if (nest_parms2 == NULL)
 502                         goto nla_put_failure;
 503
 504                 if (nla_put_string(skb, NFCTH_POLICY_NAME,
 505                                    helper->expect_policy[i].name))
 506                         goto nla_put_failure;
 507
 508                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
 509                                  htonl(helper->expect_policy[i].max_expected)))
 510                         goto nla_put_failure;
 511
 512                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
 513                                  htonl(helper->expect_policy[i].timeout)))
 514                         goto nla_put_failure;
 515
 516                 nla_nest_end(skb, nest_parms2);
 517         }
 518         nla_nest_end(skb, nest_parms1);
 519         return 0;
 520
 521 nla_put_failure:
 522         return -1;
 523 }
 524
 525 static int
 526 nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 527                         int event, struct nf_conntrack_helper *helper)
 528 {
 529         struct nlmsghdr *nlh;
 530         struct nfgenmsg *nfmsg;
 531         unsigned int flags = portid ? NLM_F_MULTI : 0;
 532         int status;
 533
 534         event = nfnl_msg_type(NFNL_SUBSYS_CTHELPER, event);
 535         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 536         if (nlh == NULL)
 537                 goto nlmsg_failure;
 538
 539         nfmsg = nlmsg_data(nlh);
 540         nfmsg->nfgen_family = AF_UNSPEC;
 541         nfmsg->version = NFNETLINK_V0;
 542         nfmsg->res_id = 0;
 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 net *net, struct sock *nfnl,
 617                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 618                              const struct nlattr * const tb[],
 619                              struct netlink_ext_ack *extack)
 620 {
 621         int ret = -ENOENT;
 622         struct nf_conntrack_helper *cur;
 623         struct sk_buff *skb2;
 624         char *helper_name = NULL;
 625         struct nf_conntrack_tuple tuple;
 626         struct nfnl_cthelper *nlcth;
 627         bool tuple_set = false;
 628
 629         if (!capable(CAP_NET_ADMIN))
 630                 return -EPERM;
 631
 632         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 633                 struct netlink_dump_control c = {
 634                         .dump = nfnl_cthelper_dump_table,
 635                 };
 636                 return netlink_dump_start(nfnl, skb, nlh, &c);
 637         }
 638
 639         if (tb[NFCTH_NAME])
 640                 helper_name = nla_data(tb[NFCTH_NAME]);
 641
 642         if (tb[NFCTH_TUPLE]) {
 643                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 644                 if (ret < 0)
 645                         return ret;
 646
 647                 tuple_set = true;
 648         }
 649
 650         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 651                 cur = &nlcth->helper;
 652                 if (helper_name &&
 653                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 654                         continue;
 655
 656                 if (tuple_set &&
 657                     (tuple.src.l3num != cur->tuple.src.l3num ||
 658                      tuple.dst.protonum != cur->tuple.dst.protonum))
 659                         continue;
 660
 661                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 662                 if (skb2 == NULL) {
 663                         ret = -ENOMEM;
 664                         break;
 665                 }
 666
 667                 ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
 668                                               nlh->nlmsg_seq,
 669                                               NFNL_MSG_TYPE(nlh->nlmsg_type),
 670                                               NFNL_MSG_CTHELPER_NEW, cur);
 671                 if (ret <= 0) {
 672                         kfree_skb(skb2);
 673                         break;
 674                 }
 675
 676                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 677                                       MSG_DONTWAIT);
 678                 if (ret > 0)
 679                         ret = 0;
 680
 681                 /* this avoids a loop in nfnetlink. */
 682                 return ret == -EAGAIN ? -ENOBUFS : ret;
 683         }
 684         return ret;
 685 }
 686
 687 static int nfnl_cthelper_del(struct net *net, struct sock *nfnl,
 688                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 689                              const struct nlattr * const tb[],
 690                              struct netlink_ext_ack *extack)
 691 {
 692         char *helper_name = NULL;
 693         struct nf_conntrack_helper *cur;
 694         struct nf_conntrack_tuple tuple;
 695         bool tuple_set = false, found = false;
 696         struct nfnl_cthelper *nlcth, *n;
 697         int j = 0, ret;
 698
 699         if (!capable(CAP_NET_ADMIN))
 700                 return -EPERM;
 701
 702         if (tb[NFCTH_NAME])
 703                 helper_name = nla_data(tb[NFCTH_NAME]);
 704
 705         if (tb[NFCTH_TUPLE]) {
 706                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 707                 if (ret < 0)
 708                         return ret;
 709
 710                 tuple_set = true;
 711         }
 712
 713         ret = -ENOENT;
 714         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 715                 cur = &nlcth->helper;
 716                 j++;
 717
 718                 if (helper_name &&
 719                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 720                         continue;
 721
 722                 if (tuple_set &&
 723                     (tuple.src.l3num != cur->tuple.src.l3num ||
 724                      tuple.dst.protonum != cur->tuple.dst.protonum))
 725                         continue;
 726
 727                 if (refcount_dec_if_one(&cur->refcnt)) {
 728                         found = true;
 729                         nf_conntrack_helper_unregister(cur);
 730                         kfree(cur->expect_policy);
 731
 732                         list_del(&nlcth->list);
 733                         kfree(nlcth);
 734                 } else {
 735                         ret = -EBUSY;
 736                 }
 737         }
 738
 739         /* Make sure we return success if we flush and there is no helpers */
 740         return (found || j == 0) ? 0 : ret;
 741 }
 742
 743 static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
 744         [NFCTH_NAME] = { .type = NLA_NUL_STRING,
 745                          .len = NF_CT_HELPER_NAME_LEN-1 },
 746         [NFCTH_QUEUE_NUM] = { .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);