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         strncpy(expect_policy->name,
 153                 nla_data(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 = kzalloc(sizeof(struct nf_conntrack_expect_policy) *
 194                                 class_max, GFP_KERNEL);
 195         if (expect_policy == NULL)
 196                 return -ENOMEM;
 197
 198         for (i = 0; i < class_max; i++) {
 199                 if (!tb[NFCTH_POLICY_SET+i])
 200                         goto err;
 201
 202                 ret = nfnl_cthelper_expect_policy(&expect_policy[i],
 203                                                   tb[NFCTH_POLICY_SET+i]);
 204                 if (ret < 0)
 205                         goto err;
 206         }
 207
 208         helper->expect_class_max = class_max - 1;
 209         helper->expect_policy = expect_policy;
 210         return 0;
 211 err:
 212         kfree(expect_policy);
 213         return -EINVAL;
 214 }
 215
 216 static int
 217 nfnl_cthelper_create(const struct nlattr * const tb[],
 218                      struct nf_conntrack_tuple *tuple)
 219 {
 220         struct nf_conntrack_helper *helper;
 221         struct nfnl_cthelper *nfcth;
 222         unsigned int size;
 223         int ret;
 224
 225         if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
 226                 return -EINVAL;
 227
 228         nfcth = kzalloc(sizeof(*nfcth), GFP_KERNEL);
 229         if (nfcth == NULL)
 230                 return -ENOMEM;
 231         helper = &nfcth->helper;
 232
 233         ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
 234         if (ret < 0)
 235                 goto err1;
 236
 237         strncpy(helper->name, nla_data(tb[NFCTH_NAME]), NF_CT_HELPER_NAME_LEN);
 238         size = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
 239         if (size > FIELD_SIZEOF(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(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[helper->expect_class_max + 1];
 318         struct nf_conntrack_expect_policy *policy;
 319         int i, err;
 320
 321         /* Check first that all policy attributes are well-formed, so we don't
 322          * leave things in inconsistent state on errors.
 323          */
 324         for (i = 0; i < helper->expect_class_max + 1; i++) {
 325
 326                 if (!tb[NFCTH_POLICY_SET + i])
 327                         return -EINVAL;
 328
 329                 err = nfnl_cthelper_update_policy_one(&helper->expect_policy[i],
 330                                                       &new_policy[i],
 331                                                       tb[NFCTH_POLICY_SET + i]);
 332                 if (err < 0)
 333                         return err;
 334         }
 335         /* Now we can safely update them. */
 336         for (i = 0; i < helper->expect_class_max + 1; i++) {
 337                 policy = (struct nf_conntrack_expect_policy *)
 338                                 &helper->expect_policy[i];
 339                 policy->max_expected = new_policy->max_expected;
 340                 policy->timeout = new_policy->timeout;
 341         }
 342
 343         return 0;
 344 }
 345
 346 static int nfnl_cthelper_update_policy(struct nf_conntrack_helper *helper,
 347                                        const struct nlattr *attr)
 348 {
 349         struct nlattr *tb[NFCTH_POLICY_SET_MAX + 1];
 350         unsigned int class_max;
 351         int err;
 352
 353         err = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
 354                                nfnl_cthelper_expect_policy_set, NULL);
 355         if (err < 0)
 356                 return err;
 357
 358         if (!tb[NFCTH_POLICY_SET_NUM])
 359                 return -EINVAL;
 360
 361         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 362         if (helper->expect_class_max + 1 != class_max)
 363                 return -EBUSY;
 364
 365         return nfnl_cthelper_update_policy_all(tb, helper);
 366 }
 367
 368 static int
 369 nfnl_cthelper_update(const struct nlattr * const tb[],
 370                      struct nf_conntrack_helper *helper)
 371 {
 372         int ret;
 373
 374         if (tb[NFCTH_PRIV_DATA_LEN])
 375                 return -EBUSY;
 376
 377         if (tb[NFCTH_POLICY]) {
 378                 ret = nfnl_cthelper_update_policy(helper, tb[NFCTH_POLICY]);
 379                 if (ret < 0)
 380                         return ret;
 381         }
 382         if (tb[NFCTH_QUEUE_NUM])
 383                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 384
 385         if (tb[NFCTH_STATUS]) {
 386                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 387
 388                 switch(status) {
 389                 case NFCT_HELPER_STATUS_ENABLED:
 390                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 391                         break;
 392                 case NFCT_HELPER_STATUS_DISABLED:
 393                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 394                         break;
 395                 }
 396         }
 397         return 0;
 398 }
 399
 400 static int nfnl_cthelper_new(struct net *net, struct sock *nfnl,
 401                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 402                              const struct nlattr * const tb[],
 403                              struct netlink_ext_ack *extack)
 404 {
 405         const char *helper_name;
 406         struct nf_conntrack_helper *cur, *helper = NULL;
 407         struct nf_conntrack_tuple tuple;
 408         struct nfnl_cthelper *nlcth;
 409         int ret = 0;
 410
 411         if (!capable(CAP_NET_ADMIN))
 412                 return -EPERM;
 413
 414         if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
 415                 return -EINVAL;
 416
 417         helper_name = nla_data(tb[NFCTH_NAME]);
 418
 419         ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 420         if (ret < 0)
 421                 return ret;
 422
 423         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 424                 cur = &nlcth->helper;
 425
 426                 if (strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 427                         continue;
 428
 429                 if ((tuple.src.l3num != cur->tuple.src.l3num ||
 430                      tuple.dst.protonum != cur->tuple.dst.protonum))
 431                         continue;
 432
 433                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 434                         return -EEXIST;
 435
 436                 helper = cur;
 437                 break;
 438         }
 439
 440         if (helper == NULL)
 441                 ret = nfnl_cthelper_create(tb, &tuple);
 442         else
 443                 ret = nfnl_cthelper_update(tb, helper);
 444
 445         return ret;
 446 }
 447
 448 static int
 449 nfnl_cthelper_dump_tuple(struct sk_buff *skb,
 450                          struct nf_conntrack_helper *helper)
 451 {
 452         struct nlattr *nest_parms;
 453
 454         nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
 455         if (nest_parms == NULL)
 456                 goto nla_put_failure;
 457
 458         if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
 459                          htons(helper->tuple.src.l3num)))
 460                 goto nla_put_failure;
 461
 462         if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
 463                 goto nla_put_failure;
 464
 465         nla_nest_end(skb, nest_parms);
 466         return 0;
 467
 468 nla_put_failure:
 469         return -1;
 470 }
 471
 472 static int
 473 nfnl_cthelper_dump_policy(struct sk_buff *skb,
 474                         struct nf_conntrack_helper *helper)
 475 {
 476         int i;
 477         struct nlattr *nest_parms1, *nest_parms2;
 478
 479         nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
 480         if (nest_parms1 == NULL)
 481                 goto nla_put_failure;
 482
 483         if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
 484                          htonl(helper->expect_class_max + 1)))
 485                 goto nla_put_failure;
 486
 487         for (i = 0; i < helper->expect_class_max + 1; i++) {
 488                 nest_parms2 = nla_nest_start(skb,
 489                                 (NFCTH_POLICY_SET+i) | NLA_F_NESTED);
 490                 if (nest_parms2 == NULL)
 491                         goto nla_put_failure;
 492
 493                 if (nla_put_string(skb, NFCTH_POLICY_NAME,
 494                                    helper->expect_policy[i].name))
 495                         goto nla_put_failure;
 496
 497                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
 498                                  htonl(helper->expect_policy[i].max_expected)))
 499                         goto nla_put_failure;
 500
 501                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
 502                                  htonl(helper->expect_policy[i].timeout)))
 503                         goto nla_put_failure;
 504
 505                 nla_nest_end(skb, nest_parms2);
 506         }
 507         nla_nest_end(skb, nest_parms1);
 508         return 0;
 509
 510 nla_put_failure:
 511         return -1;
 512 }
 513
 514 static int
 515 nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 516                         int event, struct nf_conntrack_helper *helper)
 517 {
 518         struct nlmsghdr *nlh;
 519         struct nfgenmsg *nfmsg;
 520         unsigned int flags = portid ? NLM_F_MULTI : 0;
 521         int status;
 522
 523         event = nfnl_msg_type(NFNL_SUBSYS_CTHELPER, event);
 524         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 525         if (nlh == NULL)
 526                 goto nlmsg_failure;
 527
 528         nfmsg = nlmsg_data(nlh);
 529         nfmsg->nfgen_family = AF_UNSPEC;
 530         nfmsg->version = NFNETLINK_V0;
 531         nfmsg->res_id = 0;
 532
 533         if (nla_put_string(skb, NFCTH_NAME, helper->name))
 534                 goto nla_put_failure;
 535
 536         if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
 537                 goto nla_put_failure;
 538
 539         if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
 540                 goto nla_put_failure;
 541
 542         if (nfnl_cthelper_dump_policy(skb, helper) < 0)
 543                 goto nla_put_failure;
 544
 545         if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
 546                 goto nla_put_failure;
 547
 548         if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
 549                 status = NFCT_HELPER_STATUS_ENABLED;
 550         else
 551                 status = NFCT_HELPER_STATUS_DISABLED;
 552
 553         if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
 554                 goto nla_put_failure;
 555
 556         nlmsg_end(skb, nlh);
 557         return skb->len;
 558
 559 nlmsg_failure:
 560 nla_put_failure:
 561         nlmsg_cancel(skb, nlh);
 562         return -1;
 563 }
 564
 565 static int
 566 nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
 567 {
 568         struct nf_conntrack_helper *cur, *last;
 569
 570         rcu_read_lock();
 571         last = (struct nf_conntrack_helper *)cb->args[1];
 572         for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
 573 restart:
 574                 hlist_for_each_entry_rcu(cur,
 575                                 &nf_ct_helper_hash[cb->args[0]], hnode) {
 576
 577                         /* skip non-userspace conntrack helpers. */
 578                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 579                                 continue;
 580
 581                         if (cb->args[1]) {
 582                                 if (cur != last)
 583                                         continue;
 584                                 cb->args[1] = 0;
 585                         }
 586                         if (nfnl_cthelper_fill_info(skb,
 587                                             NETLINK_CB(cb->skb).portid,
 588                                             cb->nlh->nlmsg_seq,
 589                                             NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 590                                             NFNL_MSG_CTHELPER_NEW, cur) < 0) {
 591                                 cb->args[1] = (unsigned long)cur;
 592                                 goto out;
 593                         }
 594                 }
 595         }
 596         if (cb->args[1]) {
 597                 cb->args[1] = 0;
 598                 goto restart;
 599         }
 600 out:
 601         rcu_read_unlock();
 602         return skb->len;
 603 }
 604
 605 static int nfnl_cthelper_get(struct net *net, struct sock *nfnl,
 606                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 607                              const struct nlattr * const tb[],
 608                              struct netlink_ext_ack *extack)
 609 {
 610         int ret = -ENOENT;
 611         struct nf_conntrack_helper *cur;
 612         struct sk_buff *skb2;
 613         char *helper_name = NULL;
 614         struct nf_conntrack_tuple tuple;
 615         struct nfnl_cthelper *nlcth;
 616         bool tuple_set = false;
 617
 618         if (!capable(CAP_NET_ADMIN))
 619                 return -EPERM;
 620
 621         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 622                 struct netlink_dump_control c = {
 623                         .dump = nfnl_cthelper_dump_table,
 624                 };
 625                 return netlink_dump_start(nfnl, skb, nlh, &c);
 626         }
 627
 628         if (tb[NFCTH_NAME])
 629                 helper_name = nla_data(tb[NFCTH_NAME]);
 630
 631         if (tb[NFCTH_TUPLE]) {
 632                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 633                 if (ret < 0)
 634                         return ret;
 635
 636                 tuple_set = true;
 637         }
 638
 639         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 640                 cur = &nlcth->helper;
 641                 if (helper_name &&
 642                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 643                         continue;
 644
 645                 if (tuple_set &&
 646                     (tuple.src.l3num != cur->tuple.src.l3num ||
 647                      tuple.dst.protonum != cur->tuple.dst.protonum))
 648                         continue;
 649
 650                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 651                 if (skb2 == NULL) {
 652                         ret = -ENOMEM;
 653                         break;
 654                 }
 655
 656                 ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
 657                                               nlh->nlmsg_seq,
 658                                               NFNL_MSG_TYPE(nlh->nlmsg_type),
 659                                               NFNL_MSG_CTHELPER_NEW, cur);
 660                 if (ret <= 0) {
 661                         kfree_skb(skb2);
 662                         break;
 663                 }
 664
 665                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 666                                       MSG_DONTWAIT);
 667                 if (ret > 0)
 668                         ret = 0;
 669
 670                 /* this avoids a loop in nfnetlink. */
 671                 return ret == -EAGAIN ? -ENOBUFS : ret;
 672         }
 673         return ret;
 674 }
 675
 676 static int nfnl_cthelper_del(struct net *net, struct sock *nfnl,
 677                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 678                              const struct nlattr * const tb[],
 679                              struct netlink_ext_ack *extack)
 680 {
 681         char *helper_name = NULL;
 682         struct nf_conntrack_helper *cur;
 683         struct nf_conntrack_tuple tuple;
 684         bool tuple_set = false, found = false;
 685         struct nfnl_cthelper *nlcth, *n;
 686         int j = 0, ret;
 687
 688         if (!capable(CAP_NET_ADMIN))
 689                 return -EPERM;
 690
 691         if (tb[NFCTH_NAME])
 692                 helper_name = nla_data(tb[NFCTH_NAME]);
 693
 694         if (tb[NFCTH_TUPLE]) {
 695                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 696                 if (ret < 0)
 697                         return ret;
 698
 699                 tuple_set = true;
 700         }
 701
 702         ret = -ENOENT;
 703         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 704                 cur = &nlcth->helper;
 705                 j++;
 706
 707                 if (helper_name &&
 708                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 709                         continue;
 710
 711                 if (tuple_set &&
 712                     (tuple.src.l3num != cur->tuple.src.l3num ||
 713                      tuple.dst.protonum != cur->tuple.dst.protonum))
 714                         continue;
 715
 716                 if (refcount_dec_if_one(&cur->refcnt)) {
 717                         found = true;
 718                         nf_conntrack_helper_unregister(cur);
 719                         kfree(cur->expect_policy);
 720
 721                         list_del(&nlcth->list);
 722                         kfree(nlcth);
 723                 } else {
 724                         ret = -EBUSY;
 725                 }
 726         }
 727
 728         /* Make sure we return success if we flush and there is no helpers */
 729         return (found || j == 0) ? 0 : ret;
 730 }
 731
 732 static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
 733         [NFCTH_NAME] = { .type = NLA_NUL_STRING,
 734                          .len = NF_CT_HELPER_NAME_LEN-1 },
 735         [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
 736 };
 737
 738 static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
 739         [NFNL_MSG_CTHELPER_NEW]         = { .call = nfnl_cthelper_new,
 740                                             .attr_count = NFCTH_MAX,
 741                                             .policy = nfnl_cthelper_policy },
 742         [NFNL_MSG_CTHELPER_GET]         = { .call = nfnl_cthelper_get,
 743                                             .attr_count = NFCTH_MAX,
 744                                             .policy = nfnl_cthelper_policy },
 745         [NFNL_MSG_CTHELPER_DEL]         = { .call = nfnl_cthelper_del,
 746                                             .attr_count = NFCTH_MAX,
 747                                             .policy = nfnl_cthelper_policy },
 748 };
 749
 750 static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
 751         .name                           = "cthelper",
 752         .subsys_id                      = NFNL_SUBSYS_CTHELPER,
 753         .cb_count                       = NFNL_MSG_CTHELPER_MAX,
 754         .cb                             = nfnl_cthelper_cb,
 755 };
 756
 757 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
 758
 759 static int __init nfnl_cthelper_init(void)
 760 {
 761         int ret;
 762
 763         ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
 764         if (ret < 0) {
 765                 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
 766                 goto err_out;
 767         }
 768         return 0;
 769 err_out:
 770         return ret;
 771 }
 772
 773 static void __exit nfnl_cthelper_exit(void)
 774 {
 775         struct nf_conntrack_helper *cur;
 776         struct nfnl_cthelper *nlcth, *n;
 777
 778         nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
 779
 780         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 781                 cur = &nlcth->helper;
 782
 783                 nf_conntrack_helper_unregister(cur);
 784                 kfree(cur->expect_policy);
 785                 kfree(nlcth);
 786         }
 787 }
 788
 789 module_init(nfnl_cthelper_init);
 790 module_exit(nfnl_cthelper_exit);