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         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         helper->data_len = size;
 244
 245         helper->flags |= NF_CT_HELPER_F_USERSPACE;
 246         memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
 247
 248         helper->me = THIS_MODULE;
 249         helper->help = nfnl_userspace_cthelper;
 250         helper->from_nlattr = nfnl_cthelper_from_nlattr;
 251         helper->to_nlattr = nfnl_cthelper_to_nlattr;
 252
 253         /* Default to queue number zero, this can be updated at any time. */
 254         if (tb[NFCTH_QUEUE_NUM])
 255                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 256
 257         if (tb[NFCTH_STATUS]) {
 258                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 259
 260                 switch(status) {
 261                 case NFCT_HELPER_STATUS_ENABLED:
 262                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 263                         break;
 264                 case NFCT_HELPER_STATUS_DISABLED:
 265                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 266                         break;
 267                 }
 268         }
 269
 270         ret = nf_conntrack_helper_register(helper);
 271         if (ret < 0)
 272                 goto err2;
 273
 274         list_add_tail(&nfcth->list, &nfnl_cthelper_list);
 275         return 0;
 276 err2:
 277         kfree(helper->expect_policy);
 278 err1:
 279         kfree(nfcth);
 280         return ret;
 281 }
 282
 283 static int
 284 nfnl_cthelper_update_policy_one(const struct nf_conntrack_expect_policy *policy,
 285                                 struct nf_conntrack_expect_policy *new_policy,
 286                                 const struct nlattr *attr)
 287 {
 288         struct nlattr *tb[NFCTH_POLICY_MAX + 1];
 289         int err;
 290
 291         err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr,
 292                                nfnl_cthelper_expect_pol, NULL);
 293         if (err < 0)
 294                 return err;
 295
 296         if (!tb[NFCTH_POLICY_NAME] ||
 297             !tb[NFCTH_POLICY_EXPECT_MAX] ||
 298             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
 299                 return -EINVAL;
 300
 301         if (nla_strcmp(tb[NFCTH_POLICY_NAME], policy->name))
 302                 return -EBUSY;
 303
 304         new_policy->max_expected =
 305                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
 306         if (new_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
 307                 return -EINVAL;
 308
 309         new_policy->timeout =
 310                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
 311
 312         return 0;
 313 }
 314
 315 static int nfnl_cthelper_update_policy_all(struct nlattr *tb[],
 316                                            struct nf_conntrack_helper *helper)
 317 {
 318         struct nf_conntrack_expect_policy new_policy[helper->expect_class_max + 1];
 319         struct nf_conntrack_expect_policy *policy;
 320         int i, err;
 321
 322         /* Check first that all policy attributes are well-formed, so we don't
 323          * leave things in inconsistent state on errors.
 324          */
 325         for (i = 0; i < helper->expect_class_max + 1; i++) {
 326
 327                 if (!tb[NFCTH_POLICY_SET + i])
 328                         return -EINVAL;
 329
 330                 err = nfnl_cthelper_update_policy_one(&helper->expect_policy[i],
 331                                                       &new_policy[i],
 332                                                       tb[NFCTH_POLICY_SET + i]);
 333                 if (err < 0)
 334                         return err;
 335         }
 336         /* Now we can safely update them. */
 337         for (i = 0; i < helper->expect_class_max + 1; i++) {
 338                 policy = (struct nf_conntrack_expect_policy *)
 339                                 &helper->expect_policy[i];
 340                 policy->max_expected = new_policy->max_expected;
 341                 policy->timeout = new_policy->timeout;
 342         }
 343
 344         return 0;
 345 }
 346
 347 static int nfnl_cthelper_update_policy(struct nf_conntrack_helper *helper,
 348                                        const struct nlattr *attr)
 349 {
 350         struct nlattr *tb[NFCTH_POLICY_SET_MAX + 1];
 351         unsigned int class_max;
 352         int err;
 353
 354         err = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
 355                                nfnl_cthelper_expect_policy_set, NULL);
 356         if (err < 0)
 357                 return err;
 358
 359         if (!tb[NFCTH_POLICY_SET_NUM])
 360                 return -EINVAL;
 361
 362         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
 363         if (helper->expect_class_max + 1 != class_max)
 364                 return -EBUSY;
 365
 366         return nfnl_cthelper_update_policy_all(tb, helper);
 367 }
 368
 369 static int
 370 nfnl_cthelper_update(const struct nlattr * const tb[],
 371                      struct nf_conntrack_helper *helper)
 372 {
 373         u32 size;
 374         int ret;
 375
 376         if (tb[NFCTH_PRIV_DATA_LEN]) {
 377                 size = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
 378                 if (size != helper->data_len)
 379                         return -EBUSY;
 380         }
 381
 382         if (tb[NFCTH_POLICY]) {
 383                 ret = nfnl_cthelper_update_policy(helper, tb[NFCTH_POLICY]);
 384                 if (ret < 0)
 385                         return ret;
 386         }
 387         if (tb[NFCTH_QUEUE_NUM])
 388                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
 389
 390         if (tb[NFCTH_STATUS]) {
 391                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
 392
 393                 switch(status) {
 394                 case NFCT_HELPER_STATUS_ENABLED:
 395                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
 396                         break;
 397                 case NFCT_HELPER_STATUS_DISABLED:
 398                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
 399                         break;
 400                 }
 401         }
 402         return 0;
 403 }
 404
 405 static int nfnl_cthelper_new(struct net *net, struct sock *nfnl,
 406                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 407                              const struct nlattr * const tb[],
 408                              struct netlink_ext_ack *extack)
 409 {
 410         const char *helper_name;
 411         struct nf_conntrack_helper *cur, *helper = NULL;
 412         struct nf_conntrack_tuple tuple;
 413         struct nfnl_cthelper *nlcth;
 414         int ret = 0;
 415
 416         if (!capable(CAP_NET_ADMIN))
 417                 return -EPERM;
 418
 419         if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
 420                 return -EINVAL;
 421
 422         helper_name = nla_data(tb[NFCTH_NAME]);
 423
 424         ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 425         if (ret < 0)
 426                 return ret;
 427
 428         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 429                 cur = &nlcth->helper;
 430
 431                 if (strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 432                         continue;
 433
 434                 if ((tuple.src.l3num != cur->tuple.src.l3num ||
 435                      tuple.dst.protonum != cur->tuple.dst.protonum))
 436                         continue;
 437
 438                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 439                         return -EEXIST;
 440
 441                 helper = cur;
 442                 break;
 443         }
 444
 445         if (helper == NULL)
 446                 ret = nfnl_cthelper_create(tb, &tuple);
 447         else
 448                 ret = nfnl_cthelper_update(tb, helper);
 449
 450         return ret;
 451 }
 452
 453 static int
 454 nfnl_cthelper_dump_tuple(struct sk_buff *skb,
 455                          struct nf_conntrack_helper *helper)
 456 {
 457         struct nlattr *nest_parms;
 458
 459         nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
 460         if (nest_parms == NULL)
 461                 goto nla_put_failure;
 462
 463         if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
 464                          htons(helper->tuple.src.l3num)))
 465                 goto nla_put_failure;
 466
 467         if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
 468                 goto nla_put_failure;
 469
 470         nla_nest_end(skb, nest_parms);
 471         return 0;
 472
 473 nla_put_failure:
 474         return -1;
 475 }
 476
 477 static int
 478 nfnl_cthelper_dump_policy(struct sk_buff *skb,
 479                         struct nf_conntrack_helper *helper)
 480 {
 481         int i;
 482         struct nlattr *nest_parms1, *nest_parms2;
 483
 484         nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
 485         if (nest_parms1 == NULL)
 486                 goto nla_put_failure;
 487
 488         if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
 489                          htonl(helper->expect_class_max + 1)))
 490                 goto nla_put_failure;
 491
 492         for (i = 0; i < helper->expect_class_max + 1; i++) {
 493                 nest_parms2 = nla_nest_start(skb,
 494                                 (NFCTH_POLICY_SET+i) | NLA_F_NESTED);
 495                 if (nest_parms2 == NULL)
 496                         goto nla_put_failure;
 497
 498                 if (nla_put_string(skb, NFCTH_POLICY_NAME,
 499                                    helper->expect_policy[i].name))
 500                         goto nla_put_failure;
 501
 502                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
 503                                  htonl(helper->expect_policy[i].max_expected)))
 504                         goto nla_put_failure;
 505
 506                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
 507                                  htonl(helper->expect_policy[i].timeout)))
 508                         goto nla_put_failure;
 509
 510                 nla_nest_end(skb, nest_parms2);
 511         }
 512         nla_nest_end(skb, nest_parms1);
 513         return 0;
 514
 515 nla_put_failure:
 516         return -1;
 517 }
 518
 519 static int
 520 nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 521                         int event, struct nf_conntrack_helper *helper)
 522 {
 523         struct nlmsghdr *nlh;
 524         struct nfgenmsg *nfmsg;
 525         unsigned int flags = portid ? NLM_F_MULTI : 0;
 526         int status;
 527
 528         event = nfnl_msg_type(NFNL_SUBSYS_CTHELPER, event);
 529         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 530         if (nlh == NULL)
 531                 goto nlmsg_failure;
 532
 533         nfmsg = nlmsg_data(nlh);
 534         nfmsg->nfgen_family = AF_UNSPEC;
 535         nfmsg->version = NFNETLINK_V0;
 536         nfmsg->res_id = 0;
 537
 538         if (nla_put_string(skb, NFCTH_NAME, helper->name))
 539                 goto nla_put_failure;
 540
 541         if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
 542                 goto nla_put_failure;
 543
 544         if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
 545                 goto nla_put_failure;
 546
 547         if (nfnl_cthelper_dump_policy(skb, helper) < 0)
 548                 goto nla_put_failure;
 549
 550         if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
 551                 goto nla_put_failure;
 552
 553         if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
 554                 status = NFCT_HELPER_STATUS_ENABLED;
 555         else
 556                 status = NFCT_HELPER_STATUS_DISABLED;
 557
 558         if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
 559                 goto nla_put_failure;
 560
 561         nlmsg_end(skb, nlh);
 562         return skb->len;
 563
 564 nlmsg_failure:
 565 nla_put_failure:
 566         nlmsg_cancel(skb, nlh);
 567         return -1;
 568 }
 569
 570 static int
 571 nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
 572 {
 573         struct nf_conntrack_helper *cur, *last;
 574
 575         rcu_read_lock();
 576         last = (struct nf_conntrack_helper *)cb->args[1];
 577         for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
 578 restart:
 579                 hlist_for_each_entry_rcu(cur,
 580                                 &nf_ct_helper_hash[cb->args[0]], hnode) {
 581
 582                         /* skip non-userspace conntrack helpers. */
 583                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
 584                                 continue;
 585
 586                         if (cb->args[1]) {
 587                                 if (cur != last)
 588                                         continue;
 589                                 cb->args[1] = 0;
 590                         }
 591                         if (nfnl_cthelper_fill_info(skb,
 592                                             NETLINK_CB(cb->skb).portid,
 593                                             cb->nlh->nlmsg_seq,
 594                                             NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 595                                             NFNL_MSG_CTHELPER_NEW, cur) < 0) {
 596                                 cb->args[1] = (unsigned long)cur;
 597                                 goto out;
 598                         }
 599                 }
 600         }
 601         if (cb->args[1]) {
 602                 cb->args[1] = 0;
 603                 goto restart;
 604         }
 605 out:
 606         rcu_read_unlock();
 607         return skb->len;
 608 }
 609
 610 static int nfnl_cthelper_get(struct net *net, struct sock *nfnl,
 611                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 612                              const struct nlattr * const tb[],
 613                              struct netlink_ext_ack *extack)
 614 {
 615         int ret = -ENOENT;
 616         struct nf_conntrack_helper *cur;
 617         struct sk_buff *skb2;
 618         char *helper_name = NULL;
 619         struct nf_conntrack_tuple tuple;
 620         struct nfnl_cthelper *nlcth;
 621         bool tuple_set = false;
 622
 623         if (!capable(CAP_NET_ADMIN))
 624                 return -EPERM;
 625
 626         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 627                 struct netlink_dump_control c = {
 628                         .dump = nfnl_cthelper_dump_table,
 629                 };
 630                 return netlink_dump_start(nfnl, skb, nlh, &c);
 631         }
 632
 633         if (tb[NFCTH_NAME])
 634                 helper_name = nla_data(tb[NFCTH_NAME]);
 635
 636         if (tb[NFCTH_TUPLE]) {
 637                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 638                 if (ret < 0)
 639                         return ret;
 640
 641                 tuple_set = true;
 642         }
 643
 644         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
 645                 cur = &nlcth->helper;
 646                 if (helper_name &&
 647                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 648                         continue;
 649
 650                 if (tuple_set &&
 651                     (tuple.src.l3num != cur->tuple.src.l3num ||
 652                      tuple.dst.protonum != cur->tuple.dst.protonum))
 653                         continue;
 654
 655                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 656                 if (skb2 == NULL) {
 657                         ret = -ENOMEM;
 658                         break;
 659                 }
 660
 661                 ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
 662                                               nlh->nlmsg_seq,
 663                                               NFNL_MSG_TYPE(nlh->nlmsg_type),
 664                                               NFNL_MSG_CTHELPER_NEW, cur);
 665                 if (ret <= 0) {
 666                         kfree_skb(skb2);
 667                         break;
 668                 }
 669
 670                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 671                                       MSG_DONTWAIT);
 672                 if (ret > 0)
 673                         ret = 0;
 674
 675                 /* this avoids a loop in nfnetlink. */
 676                 return ret == -EAGAIN ? -ENOBUFS : ret;
 677         }
 678         return ret;
 679 }
 680
 681 static int nfnl_cthelper_del(struct net *net, struct sock *nfnl,
 682                              struct sk_buff *skb, const struct nlmsghdr *nlh,
 683                              const struct nlattr * const tb[],
 684                              struct netlink_ext_ack *extack)
 685 {
 686         char *helper_name = NULL;
 687         struct nf_conntrack_helper *cur;
 688         struct nf_conntrack_tuple tuple;
 689         bool tuple_set = false, found = false;
 690         struct nfnl_cthelper *nlcth, *n;
 691         int j = 0, ret;
 692
 693         if (!capable(CAP_NET_ADMIN))
 694                 return -EPERM;
 695
 696         if (tb[NFCTH_NAME])
 697                 helper_name = nla_data(tb[NFCTH_NAME]);
 698
 699         if (tb[NFCTH_TUPLE]) {
 700                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
 701                 if (ret < 0)
 702                         return ret;
 703
 704                 tuple_set = true;
 705         }
 706
 707         ret = -ENOENT;
 708         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 709                 cur = &nlcth->helper;
 710                 j++;
 711
 712                 if (helper_name &&
 713                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
 714                         continue;
 715
 716                 if (tuple_set &&
 717                     (tuple.src.l3num != cur->tuple.src.l3num ||
 718                      tuple.dst.protonum != cur->tuple.dst.protonum))
 719                         continue;
 720
 721                 if (refcount_dec_if_one(&cur->refcnt)) {
 722                         found = true;
 723                         nf_conntrack_helper_unregister(cur);
 724                         kfree(cur->expect_policy);
 725
 726                         list_del(&nlcth->list);
 727                         kfree(nlcth);
 728                 } else {
 729                         ret = -EBUSY;
 730                 }
 731         }
 732
 733         /* Make sure we return success if we flush and there is no helpers */
 734         return (found || j == 0) ? 0 : ret;
 735 }
 736
 737 static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
 738         [NFCTH_NAME] = { .type = NLA_NUL_STRING,
 739                          .len = NF_CT_HELPER_NAME_LEN-1 },
 740         [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
 741         [NFCTH_PRIV_DATA_LEN] = { .type = NLA_U32, },
 742         [NFCTH_STATUS] = { .type = NLA_U32, },
 743 };
 744
 745 static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
 746         [NFNL_MSG_CTHELPER_NEW]         = { .call = nfnl_cthelper_new,
 747                                             .attr_count = NFCTH_MAX,
 748                                             .policy = nfnl_cthelper_policy },
 749         [NFNL_MSG_CTHELPER_GET]         = { .call = nfnl_cthelper_get,
 750                                             .attr_count = NFCTH_MAX,
 751                                             .policy = nfnl_cthelper_policy },
 752         [NFNL_MSG_CTHELPER_DEL]         = { .call = nfnl_cthelper_del,
 753                                             .attr_count = NFCTH_MAX,
 754                                             .policy = nfnl_cthelper_policy },
 755 };
 756
 757 static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
 758         .name                           = "cthelper",
 759         .subsys_id                      = NFNL_SUBSYS_CTHELPER,
 760         .cb_count                       = NFNL_MSG_CTHELPER_MAX,
 761         .cb                             = nfnl_cthelper_cb,
 762 };
 763
 764 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
 765
 766 static int __init nfnl_cthelper_init(void)
 767 {
 768         int ret;
 769
 770         ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
 771         if (ret < 0) {
 772                 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
 773                 goto err_out;
 774         }
 775         return 0;
 776 err_out:
 777         return ret;
 778 }
 779
 780 static void __exit nfnl_cthelper_exit(void)
 781 {
 782         struct nf_conntrack_helper *cur;
 783         struct nfnl_cthelper *nlcth, *n;
 784
 785         nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
 786
 787         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
 788                 cur = &nlcth->helper;
 789
 790                 nf_conntrack_helper_unregister(cur);
 791                 kfree(cur->expect_policy);
 792                 kfree(nlcth);
 793         }
 794 }
 795
 796 module_init(nfnl_cthelper_init);
 797 module_exit(nfnl_cthelper_exit);