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_slow */
  55         helper = rcu_dereference(help->helper);
  56         if (helper == NULL)
  57                 return NF_DROP;
  58
  59         /* This is an 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, nfnl_cthelper_tuple_pol);
  82         if (err < 0)
  83                 return err;
  84
  85         if (!tb[NFCTH_TUPLE_L3PROTONUM] || !tb[NFCTH_TUPLE_L4PROTONUM])
  86                 return -EINVAL;
  87
  88         /* Not all fields are initialized so first zero the tuple */
  89         memset(tuple, 0, sizeof(struct nf_conntrack_tuple));
  90
  91         tuple->src.l3num = ntohs(nla_get_be16(tb[NFCTH_TUPLE_L3PROTONUM]));
  92         tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]);
  93
  94         return 0;
  95 }
  96
  97 static int
  98 nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
  99 {
 100         struct nf_conn_help *help = nfct_help(ct);
 101
 102         if (attr == NULL)
 103                 return -EINVAL;
 104
 105         if (help->helper->data_len == 0)
 106                 return -EINVAL;
 107
 108         memcpy(help->data, nla_data(attr), help->helper->data_len);
 109         return 0;
 110 }
 111
 112 static int
 113 nfnl_cthelper_to_nlattr(struct sk_buff *skb, const struct nf_conn *ct)
 114 {
 115         const struct nf_conn_help *help = nfct_help(ct);
 116
 117         if (help->helper->data_len &&
 118             nla_put(skb, CTA_HELP_INFO, help->helper->data_len, &help->data))
 119                 goto nla_put_failure;
 120
 121         return 0;
 122
 123 nla_put_failure:
 124         return -ENOSPC;
 125 }
 126
 127 static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = {
 128         [NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING,
 129                                 .len = NF_CT_HELPER_NAME_LEN-1 },
 130         [NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, },
 131         [NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, },
 132 };
 133
 134 static int
 135 nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy,
 136                             const struct nlattr *attr)
 137 {
 138         int err;
 139         struct nlattr *tb[NFCTH_POLICY_MAX+1];
 140
 141         err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr, nfnl_cthelper_expect_pol);
 142         if (err < 0)
 143                 return err;
 144
 145         if (!tb[NFCTH_POLICY_NAME] ||
 146             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 147             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 148                 return -EINVAL;
 149
 150         strncpy(expect_policy->name,
 151                 nla_data(tb[NFCTH_POLICY_NAME]), NF_CT_HELPER_NAME_LEN);
 152         expect_policy->max_expected =
 153                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 154         expect_policy->timeout =
 155                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 156
 157         return 0;
 158 }
 159
 160 static const struct nla_policy
 161 nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
 162         [NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, },
 163 };
 164
 165 static int
 166 nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper,
 167                                   const struct nlattr *attr)
 168 {
 169         int i, ret;
 170         struct nf_conntrack_expect_policy *expect_policy;
 171         struct nlattr *tb[NFCTH_POLICY_SET_MAX+1];
 172         unsigned int class_max;
 173
 174         ret = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
 175                                nfnl_cthelper_expect_policy_set);
 176         if (ret < 0)
 177                 return ret;
 178
 179         if (!tb[NFCTH_POLICY_SET_NUM])
 180                 return -EINVAL;
 181
 182         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 183         if (class_max == 0)
 184                 return -EINVAL;
 185         if (class_max > NF_CT_MAX_EXPECT_CLASSES)
 186                 return -EOVERFLOW;
 187
 188         expect_policy = kzalloc(sizeof(struct nf_conntrack_expect_policy) *
 189                                 class_max, GFP_KERNEL);
 190         if (expect_policy == NULL)
 191                 return -ENOMEM;
 192
 193         for (i = 0; i < class_max; i++) {
 194                 if (!tb[NFCTH_POLICY_SET+i])
 195                         goto err;
 196
 197                 ret = nfnl_cthelper_expect_policy(&expect_policy[i],
 198                                                   tb[NFCTH_POLICY_SET+i]);
 199                 if (ret < 0)
 200                         goto err;
 201         }
 202
 203         helper->expect_class_max = class_max - 1;
 204         helper->expect_policy = expect_policy;
 205         return 0;
 206 err:
 207         kfree(expect_policy);
 208         return -EINVAL;
 209 }
 210
 211 static int
 212 nfnl_cthelper_create(const struct nlattr * const tb[],
 213                      struct nf_conntrack_tuple *tuple)
 214 {
 215         struct nf_conntrack_helper *helper;
 216         struct nfnl_cthelper *nfcth;
 217         int ret;
 218
 219         if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
 220                 return -EINVAL;
 221
 222         nfcth = kzalloc(sizeof(*nfcth), GFP_KERNEL);
 223         if (nfcth == NULL)
 224                 return -ENOMEM;
 225         helper = &nfcth->helper;
 226
 227         ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
 228         if (ret < 0)
 229                 goto err1;
 230
 231         strncpy(helper->name, nla_data(tb[NFCTH_NAME]), NF_CT_HELPER_NAME_LEN);
 232         helper->data_len = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
 233         helper->flags |= NF_CT_HELPER_F_USERSPACE;
 234         memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
 235
 236         helper->me = THIS_MODULE;
 237         helper->help = nfnl_userspace_cthelper;
 238         helper->from_nlattr = nfnl_cthelper_from_nlattr;
 239         helper->to_nlattr = nfnl_cthelper_to_nlattr;
 240
 241         /* Default to queue number zero, this can be updated at any time. */
 242         if (tb[NFCTH_QUEUE_NUM])
 243                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 244
 245         if (tb[NFCTH_STATUS]) {
 246                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 247
 248                 switch(status) {
 249                 case NFCT_HELPER_STATUS_ENABLED:
 250                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 251                         break;
 252                 case NFCT_HELPER_STATUS_DISABLED:
 253                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 254                         break;
 255                 }
 256         }
 257
 258         ret = nf_conntrack_helper_register(helper);
 259         if (ret < 0)
 260                 goto err2;
 261
 262         list_add_tail(&nfcth->list, &nfnl_cthelper_list);
 263         return 0;
 264 err2:
 265         kfree(helper->expect_policy);
 266 err1:
 267         kfree(nfcth);
 268         return ret;
 269 }
 270
 271 static int
 272 nfnl_cthelper_update_policy_one(const struct nf_conntrack_expect_policy *policy,
 273                                 struct nf_conntrack_expect_policy *new_policy,
 274                                 const struct nlattr *attr)
 275 {
 276         struct nlattr *tb[NFCTH_POLICY_MAX + 1];
 277         int err;
 278
 279         err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr,
 280                                nfnl_cthelper_expect_pol);
 281         if (err < 0)
 282                 return err;
 283
 284         if (!tb[NFCTH_POLICY_NAME] ||
 285             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 286             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 287                 return -EINVAL;
 288
 289         if (nla_strcmp(tb[NFCTH_POLICY_NAME], policy->name))
 290                 return -EBUSY;
 291
 292         new_policy->max_expected =
 293                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 294         new_policy->timeout =
 295                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 296
 297         return 0;
 298 }
 299
 300 static int nfnl_cthelper_update_policy_all(struct nlattr *tb[],
 301                                            struct nf_conntrack_helper *helper)
 302 {
 303         struct nf_conntrack_expect_policy new_policy[helper->expect_class_max + 1];
 304         struct nf_conntrack_expect_policy *policy;
 305         int i, err;
 306
 307         /* Check first that all policy attributes are well-formed, so we don't
 308          * leave things in inconsistent state on errors.
 309          */
 310         for (i = 0; i < helper->expect_class_max + 1; i++) {
 311
 312                 if (!tb[NFCTH_POLICY_SET + i])
 313                         return -EINVAL;
 314
 315                 err = nfnl_cthelper_update_policy_one(&helper->expect_policy[i],
 316                                                       &new_policy[i],
 317                                                       tb[NFCTH_POLICY_SET + i]);
 318                 if (err < 0)
 319                         return err;
 320         }
 321         /* Now we can safely update them. */
 322         for (i = 0; i < helper->expect_class_max + 1; i++) {
 323                 policy = (struct nf_conntrack_expect_policy *)
 324                                 &helper->expect_policy[i];
 325                 policy->max_expected = new_policy->max_expected;
 326                 policy->timeout = new_policy->timeout;
 327         }
 328
 329         return 0;
 330 }
 331
 332 static int nfnl_cthelper_update_policy(struct nf_conntrack_helper *helper,
 333                                        const struct nlattr *attr)
 334 {
 335         struct nlattr *tb[NFCTH_POLICY_SET_MAX + 1];
 336         unsigned int class_max;
 337         int err;
 338
 339         err = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
 340                                nfnl_cthelper_expect_policy_set);
 341         if (err < 0)
 342                 return err;
 343
 344         if (!tb[NFCTH_POLICY_SET_NUM])
 345                 return -EINVAL;
 346
 347         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 348         if (helper->expect_class_max + 1 != class_max)
 349                 return -EBUSY;
 350
 351         return nfnl_cthelper_update_policy_all(tb, helper);
 352 }
 353
 354 static int
 355 nfnl_cthelper_update(const struct nlattr * const tb[],
 356                      struct nf_conntrack_helper *helper)
 357 {
 358         int ret;
 359
 360         if (tb[NFCTH_PRIV_DATA_LEN])
 361                 return -EBUSY;
 362
 363         if (tb[NFCTH_POLICY]) {
 364                 ret = nfnl_cthelper_update_policy(helper, tb[NFCTH_POLICY]);
 365                 if (ret < 0)
 366                         return ret;
 367         }
 368         if (tb[NFCTH_QUEUE_NUM])
 369                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 370
 371         if (tb[NFCTH_STATUS]) {
 372                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 373
 374                 switch(status) {
 375                 case NFCT_HELPER_STATUS_ENABLED:
 376                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 377                         break;
 378                 case NFCT_HELPER_STATUS_DISABLED:
 379                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 380                         break;
 381                 }
 382         }
 383         return 0;
 384 }
 385
 386 static int
 387 nfnl_cthelper_new(struct sock *nfnl, struct sk_buff *skb,
 388                   const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 389 {
 390         const char *helper_name;
 391         struct nf_conntrack_helper *cur, *helper = NULL;
 392         struct nf_conntrack_tuple tuple;
 393         struct nfnl_cthelper *nlcth;
 394         int ret = 0;
 395
 396         if (!capable(CAP_NET_ADMIN))
 397                 return -EPERM;
 398
 399         if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
 400                 return -EINVAL;
 401
 402         helper_name = nla_data(tb[NFCTH_NAME]);
 403
 404         ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 405         if (ret < 0)
 406                 return ret;
 407
 408         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 409                 cur = &nlcth->helper;
 410
 411                 if (strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 412                         continue;
 413
 414                 if ((tuple.src.l3num != cur->tuple.src.l3num ||
 415                      tuple.dst.protonum != cur->tuple.dst.protonum))
 416                         continue;
 417
 418                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 419                         return -EEXIST;
 420
 421                 helper = cur;
 422                 break;
 423         }
 424
 425         if (helper == NULL)
 426                 ret = nfnl_cthelper_create(tb, &tuple);
 427         else
 428                 ret = nfnl_cthelper_update(tb, helper);
 429
 430         return ret;
 431 }
 432
 433 static int
 434 nfnl_cthelper_dump_tuple(struct sk_buff *skb,
 435                          struct nf_conntrack_helper *helper)
 436 {
 437         struct nlattr *nest_parms;
 438
 439         nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
 440         if (nest_parms == NULL)
 441                 goto nla_put_failure;
 442
 443         if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
 444                          htons(helper->tuple.src.l3num)))
 445                 goto nla_put_failure;
 446
 447         if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
 448                 goto nla_put_failure;
 449
 450         nla_nest_end(skb, nest_parms);
 451         return 0;
 452
 453 nla_put_failure:
 454         return -1;
 455 }
 456
 457 static int
 458 nfnl_cthelper_dump_policy(struct sk_buff *skb,
 459                         struct nf_conntrack_helper *helper)
 460 {
 461         int i;
 462         struct nlattr *nest_parms1, *nest_parms2;
 463
 464         nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
 465         if (nest_parms1 == NULL)
 466                 goto nla_put_failure;
 467
 468         if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
 469                          htonl(helper->expect_class_max + 1)))
 470                 goto nla_put_failure;
 471
 472         for (i = 0; i < helper->expect_class_max + 1; i++) {
 473                 nest_parms2 = nla_nest_start(skb,
 474                                 (NFCTH_POLICY_SET+i) | NLA_F_NESTED);
 475                 if (nest_parms2 == NULL)
 476                         goto nla_put_failure;
 477
 478                 if (nla_put_string(skb, NFCTH_POLICY_NAME,
 479                                    helper->expect_policy[i].name))
 480                         goto nla_put_failure;
 481
 482                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
 483                                  htonl(helper->expect_policy[i].max_expected)))
 484                         goto nla_put_failure;
 485
 486                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
 487                                  htonl(helper->expect_policy[i].timeout)))
 488                         goto nla_put_failure;
 489
 490                 nla_nest_end(skb, nest_parms2);
 491         }
 492         nla_nest_end(skb, nest_parms1);
 493         return 0;
 494
 495 nla_put_failure:
 496         return -1;
 497 }
 498
 499 static int
 500 nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 501                         int event, struct nf_conntrack_helper *helper)
 502 {
 503         struct nlmsghdr *nlh;
 504         struct nfgenmsg *nfmsg;
 505         unsigned int flags = portid ? NLM_F_MULTI : 0;
 506         int status;
 507
 508         event |= NFNL_SUBSYS_CTHELPER << 8;
 509         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 510         if (nlh == NULL)
 511                 goto nlmsg_failure;
 512
 513         nfmsg = nlmsg_data(nlh);
 514         nfmsg->nfgen_family = AF_UNSPEC;
 515         nfmsg->version = NFNETLINK_V0;
 516         nfmsg->res_id = 0;
 517
 518         if (nla_put_string(skb, NFCTH_NAME, helper->name))
 519                 goto nla_put_failure;
 520
 521         if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
 522                 goto nla_put_failure;
 523
 524         if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
 525                 goto nla_put_failure;
 526
 527         if (nfnl_cthelper_dump_policy(skb, helper) < 0)
 528                 goto nla_put_failure;
 529
 530         if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
 531                 goto nla_put_failure;
 532
 533         if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
 534                 status = NFCT_HELPER_STATUS_ENABLED;
 535         else
 536                 status = NFCT_HELPER_STATUS_DISABLED;
 537
 538         if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
 539                 goto nla_put_failure;
 540
 541         nlmsg_end(skb, nlh);
 542         return skb->len;
 543
 544 nlmsg_failure:
 545 nla_put_failure:
 546         nlmsg_cancel(skb, nlh);
 547         return -1;
 548 }
 549
 550 static int
 551 nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
 552 {
 553         struct nf_conntrack_helper *cur, *last;
 554
 555         rcu_read_lock();
 556         last = (struct nf_conntrack_helper *)cb->args[1];
 557         for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
 558 restart:
 559                 hlist_for_each_entry_rcu(cur,
 560                                 &nf_ct_helper_hash[cb->args[0]], hnode) {
 561
 562                         /* skip non-userspace conntrack helpers. */
 563                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 564                                 continue;
 565
 566                         if (cb->args[1]) {
 567                                 if (cur != last)
 568                                         continue;
 569                                 cb->args[1] = 0;
 570                         }
 571                         if (nfnl_cthelper_fill_info(skb,
 572                                             NETLINK_CB(cb->skb).portid,
 573                                             cb->nlh->nlmsg_seq,
 574                                             NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 575                                             NFNL_MSG_CTHELPER_NEW, cur) < 0) {
 576                                 cb->args[1] = (unsigned long)cur;
 577                                 goto out;
 578                         }
 579                 }
 580         }
 581         if (cb->args[1]) {
 582                 cb->args[1] = 0;
 583                 goto restart;
 584         }
 585 out:
 586         rcu_read_unlock();
 587         return skb->len;
 588 }
 589
 590 static int
 591 nfnl_cthelper_get(struct sock *nfnl, struct sk_buff *skb,
 592                   const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 593 {
 594         int ret = -ENOENT;
 595         struct nf_conntrack_helper *cur;
 596         struct sk_buff *skb2;
 597         char *helper_name = NULL;
 598         struct nf_conntrack_tuple tuple;
 599         struct nfnl_cthelper *nlcth;
 600         bool tuple_set = false;
 601
 602         if (!capable(CAP_NET_ADMIN))
 603                 return -EPERM;
 604
 605         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 606                 struct netlink_dump_control c = {
 607                         .dump = nfnl_cthelper_dump_table,
 608                 };
 609                 return netlink_dump_start(nfnl, skb, nlh, &c);
 610         }
 611
 612         if (tb[NFCTH_NAME])
 613                 helper_name = nla_data(tb[NFCTH_NAME]);
 614
 615         if (tb[NFCTH_TUPLE]) {
 616                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 617                 if (ret < 0)
 618                         return ret;
 619
 620                 tuple_set = true;
 621         }
 622
 623         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 624                 cur = &nlcth->helper;
 625                 if (helper_name &&
 626                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 627                         continue;
 628
 629                 if (tuple_set &&
 630                     (tuple.src.l3num != cur->tuple.src.l3num ||
 631                      tuple.dst.protonum != cur->tuple.dst.protonum))
 632                         continue;
 633
 634                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 635                 if (skb2 == NULL) {
 636                         ret = -ENOMEM;
 637                         break;
 638                 }
 639
 640                 ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
 641                                               nlh->nlmsg_seq,
 642                                               NFNL_MSG_TYPE(nlh->nlmsg_type),
 643                                               NFNL_MSG_CTHELPER_NEW, cur);
 644                 if (ret <= 0) {
 645                         kfree_skb(skb2);
 646                         break;
 647                 }
 648
 649                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 650                                       MSG_DONTWAIT);
 651                 if (ret > 0)
 652                         ret = 0;
 653
 654                 /* this avoids a loop in nfnetlink. */
 655                 return ret == -EAGAIN ? -ENOBUFS : ret;
 656         }
 657         return ret;
 658 }
 659
 660 static int
 661 nfnl_cthelper_del(struct sock *nfnl, struct sk_buff *skb,
 662              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 663 {
 664         char *helper_name = NULL;
 665         struct nf_conntrack_helper *cur;
 666         struct nf_conntrack_tuple tuple;
 667         bool tuple_set = false, found = false;
 668         struct nfnl_cthelper *nlcth, *n;
 669         int j = 0, ret;
 670
 671         if (!capable(CAP_NET_ADMIN))
 672                 return -EPERM;
 673
 674         if (tb[NFCTH_NAME])
 675                 helper_name = nla_data(tb[NFCTH_NAME]);
 676
 677         if (tb[NFCTH_TUPLE]) {
 678                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 679                 if (ret < 0)
 680                         return ret;
 681
 682                 tuple_set = true;
 683         }
 684
 685         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 686                 cur = &nlcth->helper;
 687                 j++;
 688
 689                 if (helper_name &&
 690                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 691                         continue;
 692
 693                 if (tuple_set &&
 694                     (tuple.src.l3num != cur->tuple.src.l3num ||
 695                      tuple.dst.protonum != cur->tuple.dst.protonum))
 696                         continue;
 697
 698                 found = true;
 699                 nf_conntrack_helper_unregister(cur);
 700                 kfree(cur->expect_policy);
 701
 702                 list_del(&nlcth->list);
 703                 kfree(nlcth);
 704         }
 705
 706         /* Make sure we return success if we flush and there is no helpers */
 707         return (found || j == 0) ? 0 : -ENOENT;
 708 }
 709
 710 static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
 711         [NFCTH_NAME] = { .type = NLA_NUL_STRING,
 712                          .len = NF_CT_HELPER_NAME_LEN-1 },
 713         [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
 714         [NFCTH_PRIV_DATA_LEN] = { .type = NLA_U32, },
 715         [NFCTH_STATUS] = { .type = NLA_U32, },
 716 };
 717
 718 static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
 719         [NFNL_MSG_CTHELPER_NEW]         = { .call = nfnl_cthelper_new,
 720                                             .attr_count = NFCTH_MAX,
 721                                             .policy = nfnl_cthelper_policy },
 722         [NFNL_MSG_CTHELPER_GET]         = { .call = nfnl_cthelper_get,
 723                                             .attr_count = NFCTH_MAX,
 724                                             .policy = nfnl_cthelper_policy },
 725         [NFNL_MSG_CTHELPER_DEL]         = { .call = nfnl_cthelper_del,
 726                                             .attr_count = NFCTH_MAX,
 727                                             .policy = nfnl_cthelper_policy },
 728 };
 729
 730 static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
 731         .name                           = "cthelper",
 732         .subsys_id                      = NFNL_SUBSYS_CTHELPER,
 733         .cb_count                       = NFNL_MSG_CTHELPER_MAX,
 734         .cb                             = nfnl_cthelper_cb,
 735 };
 736
 737 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
 738
 739 static int __init nfnl_cthelper_init(void)
 740 {
 741         int ret;
 742
 743         ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
 744         if (ret < 0) {
 745                 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
 746                 goto err_out;
 747         }
 748         return 0;
 749 err_out:
 750         return ret;
 751 }
 752
 753 static void __exit nfnl_cthelper_exit(void)
 754 {
 755         struct nf_conntrack_helper *cur;
 756         struct nfnl_cthelper *nlcth, *n;
 757
 758         nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
 759
 760         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 761                 cur = &nlcth->helper;
 762
 763                 nf_conntrack_helper_unregister(cur);
 764                 kfree(cur->expect_policy);
 765                 kfree(nlcth);
 766         }
 767 }
 768
 769 module_init(nfnl_cthelper_init);
 770 module_exit(nfnl_cthelper_exit);