net/netfilter/nfnetlink_cttimeout.c

   1 /*
   2  * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
   3  * (C) 2012 by Vyatta Inc. <http://www.vyatta.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation (or any later at your option).
   8  */
   9 #include <linux/init.h>
  10 #include <linux/module.h>
  11 #include <linux/kernel.h>
  12 #include <linux/rculist.h>
  13 #include <linux/rculist_nulls.h>
  14 #include <linux/types.h>
  15 #include <linux/timer.h>
  16 #include <linux/security.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/errno.h>
  19 #include <linux/netlink.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/slab.h>
  23
  24 #include <linux/netfilter.h>
  25 #include <net/netlink.h>
  26 #include <net/sock.h>
  27 #include <net/netfilter/nf_conntrack.h>
  28 #include <net/netfilter/nf_conntrack_core.h>
  29 #include <net/netfilter/nf_conntrack_l4proto.h>
  30 #include <net/netfilter/nf_conntrack_tuple.h>
  31 #include <net/netfilter/nf_conntrack_timeout.h>
  32
  33 #include <linux/netfilter/nfnetlink.h>
  34 #include <linux/netfilter/nfnetlink_cttimeout.h>
  35
  36 MODULE_LICENSE("GPL");
  37 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
  38 MODULE_DESCRIPTION("cttimeout: Extended Netfilter Connection Tracking timeout tuning");
  39
  40 static const struct nla_policy cttimeout_nla_policy[CTA_TIMEOUT_MAX+1] = {
  41         [CTA_TIMEOUT_NAME]      = { .type = NLA_NUL_STRING,
  42                                     .len  = CTNL_TIMEOUT_NAME_MAX - 1},
  43         [CTA_TIMEOUT_L3PROTO]   = { .type = NLA_U16 },
  44         [CTA_TIMEOUT_L4PROTO]   = { .type = NLA_U8 },
  45         [CTA_TIMEOUT_DATA]      = { .type = NLA_NESTED },
  46 };
  47
  48 static int
  49 ctnl_timeout_parse_policy(void *timeout,
  50                           const struct nf_conntrack_l4proto *l4proto,
  51                           struct net *net, const struct nlattr *attr)
  52 {
  53         struct nlattr **tb;
  54         int ret = 0;
  55
  56         if (!l4proto->ctnl_timeout.nlattr_to_obj)
  57                 return 0;
  58
  59         tb = kcalloc(l4proto->ctnl_timeout.nlattr_max + 1, sizeof(*tb),
  60                      GFP_KERNEL);
  61
  62         if (!tb)
  63                 return -ENOMEM;
  64
  65         ret = nla_parse_nested(tb, l4proto->ctnl_timeout.nlattr_max, attr,
  66                                l4proto->ctnl_timeout.nla_policy, NULL);
  67         if (ret < 0)
  68                 goto err;
  69
  70         ret = l4proto->ctnl_timeout.nlattr_to_obj(tb, net, timeout);
  71
  72 err:
  73         kfree(tb);
  74         return ret;
  75 }
  76
  77 static int cttimeout_new_timeout(struct net *net, struct sock *ctnl,
  78                                  struct sk_buff *skb,
  79                                  const struct nlmsghdr *nlh,
  80                                  const struct nlattr * const cda[],
  81                                  struct netlink_ext_ack *extack)
  82 {
  83         __u16 l3num;
  84         __u8 l4num;
  85         const struct nf_conntrack_l4proto *l4proto;
  86         struct ctnl_timeout *timeout, *matching = NULL;
  87         char *name;
  88         int ret;
  89
  90         if (!cda[CTA_TIMEOUT_NAME] ||
  91             !cda[CTA_TIMEOUT_L3PROTO] ||
  92             !cda[CTA_TIMEOUT_L4PROTO] ||
  93             !cda[CTA_TIMEOUT_DATA])
  94                 return -EINVAL;
  95
  96         name = nla_data(cda[CTA_TIMEOUT_NAME]);
  97         l3num = ntohs(nla_get_be16(cda[CTA_TIMEOUT_L3PROTO]));
  98         l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]);
  99
 100         list_for_each_entry(timeout, &net->nfct_timeout_list, head) {
 101                 if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 102                         continue;
 103
 104                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 105                         return -EEXIST;
 106
 107                 matching = timeout;
 108                 break;
 109         }
 110
 111         if (matching) {
 112                 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
 113                         /* You cannot replace one timeout policy by another of
 114                          * different kind, sorry.
 115                          */
 116                         if (matching->timeout.l3num != l3num ||
 117                             matching->timeout.l4proto->l4proto != l4num)
 118                                 return -EINVAL;
 119
 120                         return ctnl_timeout_parse_policy(&matching->timeout.data,
 121                                                          matching->timeout.l4proto,
 122                                                          net, cda[CTA_TIMEOUT_DATA]);
 123                 }
 124
 125                 return -EBUSY;
 126         }
 127
 128         l4proto = nf_ct_l4proto_find_get(l3num, l4num);
 129
 130         /* This protocol is not supportted, skip. */
 131         if (l4proto->l4proto != l4num) {
 132                 ret = -EOPNOTSUPP;
 133                 goto err_proto_put;
 134         }
 135
 136         timeout = kzalloc(sizeof(struct ctnl_timeout) +
 137                           l4proto->ctnl_timeout.obj_size, GFP_KERNEL);
 138         if (timeout == NULL) {
 139                 ret = -ENOMEM;
 140                 goto err_proto_put;
 141         }
 142
 143         ret = ctnl_timeout_parse_policy(&timeout->timeout.data, l4proto, net,
 144                                         cda[CTA_TIMEOUT_DATA]);
 145         if (ret < 0)
 146                 goto err;
 147
 148         strcpy(timeout->name, nla_data(cda[CTA_TIMEOUT_NAME]));
 149         timeout->timeout.l3num = l3num;
 150         timeout->timeout.l4proto = l4proto;
 151         refcount_set(&timeout->refcnt, 1);
 152         list_add_tail_rcu(&timeout->head, &net->nfct_timeout_list);
 153
 154         return 0;
 155 err:
 156         kfree(timeout);
 157 err_proto_put:
 158         nf_ct_l4proto_put(l4proto);
 159         return ret;
 160 }
 161
 162 static int
 163 ctnl_timeout_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 164                        int event, struct ctnl_timeout *timeout)
 165 {
 166         struct nlmsghdr *nlh;
 167         struct nfgenmsg *nfmsg;
 168         unsigned int flags = portid ? NLM_F_MULTI : 0;
 169         const struct nf_conntrack_l4proto *l4proto = timeout->timeout.l4proto;
 170
 171         event = nfnl_msg_type(NFNL_SUBSYS_CTNETLINK_TIMEOUT, event);
 172         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 173         if (nlh == NULL)
 174                 goto nlmsg_failure;
 175
 176         nfmsg = nlmsg_data(nlh);
 177         nfmsg->nfgen_family = AF_UNSPEC;
 178         nfmsg->version = NFNETLINK_V0;
 179         nfmsg->res_id = 0;
 180
 181         if (nla_put_string(skb, CTA_TIMEOUT_NAME, timeout->name) ||
 182             nla_put_be16(skb, CTA_TIMEOUT_L3PROTO,
 183                          htons(timeout->timeout.l3num)) ||
 184             nla_put_u8(skb, CTA_TIMEOUT_L4PROTO, l4proto->l4proto) ||
 185             nla_put_be32(skb, CTA_TIMEOUT_USE,
 186                          htonl(refcount_read(&timeout->refcnt))))
 187                 goto nla_put_failure;
 188
 189         if (likely(l4proto->ctnl_timeout.obj_to_nlattr)) {
 190                 struct nlattr *nest_parms;
 191                 int ret;
 192
 193                 nest_parms = nla_nest_start(skb,
 194                                             CTA_TIMEOUT_DATA | NLA_F_NESTED);
 195                 if (!nest_parms)
 196                         goto nla_put_failure;
 197
 198                 ret = l4proto->ctnl_timeout.obj_to_nlattr(skb,
 199                                                         &timeout->timeout.data);
 200                 if (ret < 0)
 201                         goto nla_put_failure;
 202
 203                 nla_nest_end(skb, nest_parms);
 204         }
 205
 206         nlmsg_end(skb, nlh);
 207         return skb->len;
 208
 209 nlmsg_failure:
 210 nla_put_failure:
 211         nlmsg_cancel(skb, nlh);
 212         return -1;
 213 }
 214
 215 static int
 216 ctnl_timeout_dump(struct sk_buff *skb, struct netlink_callback *cb)
 217 {
 218         struct net *net = sock_net(skb->sk);
 219         struct ctnl_timeout *cur, *last;
 220
 221         if (cb->args[2])
 222                 return 0;
 223
 224         last = (struct ctnl_timeout *)cb->args[1];
 225         if (cb->args[1])
 226                 cb->args[1] = 0;
 227
 228         rcu_read_lock();
 229         list_for_each_entry_rcu(cur, &net->nfct_timeout_list, head) {
 230                 if (last) {
 231                         if (cur != last)
 232                                 continue;
 233
 234                         last = NULL;
 235                 }
 236                 if (ctnl_timeout_fill_info(skb, NETLINK_CB(cb->skb).portid,
 237                                            cb->nlh->nlmsg_seq,
 238                                            NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 239                                            IPCTNL_MSG_TIMEOUT_NEW, cur) < 0) {
 240                         cb->args[1] = (unsigned long)cur;
 241                         break;
 242                 }
 243         }
 244         if (!cb->args[1])
 245                 cb->args[2] = 1;
 246         rcu_read_unlock();
 247         return skb->len;
 248 }
 249
 250 static int cttimeout_get_timeout(struct net *net, struct sock *ctnl,
 251                                  struct sk_buff *skb,
 252                                  const struct nlmsghdr *nlh,
 253                                  const struct nlattr * const cda[],
 254                                  struct netlink_ext_ack *extack)
 255 {
 256         int ret = -ENOENT;
 257         char *name;
 258         struct ctnl_timeout *cur;
 259
 260         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 261                 struct netlink_dump_control c = {
 262                         .dump = ctnl_timeout_dump,
 263                 };
 264                 return netlink_dump_start(ctnl, skb, nlh, &c);
 265         }
 266
 267         if (!cda[CTA_TIMEOUT_NAME])
 268                 return -EINVAL;
 269         name = nla_data(cda[CTA_TIMEOUT_NAME]);
 270
 271         list_for_each_entry(cur, &net->nfct_timeout_list, head) {
 272                 struct sk_buff *skb2;
 273
 274                 if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 275                         continue;
 276
 277                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 278                 if (skb2 == NULL) {
 279                         ret = -ENOMEM;
 280                         break;
 281                 }
 282
 283                 ret = ctnl_timeout_fill_info(skb2, NETLINK_CB(skb).portid,
 284                                              nlh->nlmsg_seq,
 285                                              NFNL_MSG_TYPE(nlh->nlmsg_type),
 286                                              IPCTNL_MSG_TIMEOUT_NEW, cur);
 287                 if (ret <= 0) {
 288                         kfree_skb(skb2);
 289                         break;
 290                 }
 291                 ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).portid,
 292                                         MSG_DONTWAIT);
 293                 if (ret > 0)
 294                         ret = 0;
 295
 296                 /* this avoids a loop in nfnetlink. */
 297                 return ret == -EAGAIN ? -ENOBUFS : ret;
 298         }
 299         return ret;
 300 }
 301
 302 /* try to delete object, fail if it is still in use. */
 303 static int ctnl_timeout_try_del(struct net *net, struct ctnl_timeout *timeout)
 304 {
 305         int ret = 0;
 306
 307         /* We want to avoid races with ctnl_timeout_put. So only when the
 308          * current refcnt is 1, we decrease it to 0.
 309          */
 310         if (refcount_dec_if_one(&timeout->refcnt)) {
 311                 /* We are protected by nfnl mutex. */
 312                 list_del_rcu(&timeout->head);
 313                 nf_ct_l4proto_put(timeout->timeout.l4proto);
 314                 nf_ct_untimeout(net, &timeout->timeout);
 315                 kfree_rcu(timeout, rcu_head);
 316         } else {
 317                 ret = -EBUSY;
 318         }
 319         return ret;
 320 }
 321
 322 static int cttimeout_del_timeout(struct net *net, struct sock *ctnl,
 323                                  struct sk_buff *skb,
 324                                  const struct nlmsghdr *nlh,
 325                                  const struct nlattr * const cda[],
 326                                  struct netlink_ext_ack *extack)
 327 {
 328         struct ctnl_timeout *cur, *tmp;
 329         int ret = -ENOENT;
 330         char *name;
 331
 332         if (!cda[CTA_TIMEOUT_NAME]) {
 333                 list_for_each_entry_safe(cur, tmp, &net->nfct_timeout_list,
 334                                          head)
 335                         ctnl_timeout_try_del(net, cur);
 336
 337                 return 0;
 338         }
 339         name = nla_data(cda[CTA_TIMEOUT_NAME]);
 340
 341         list_for_each_entry(cur, &net->nfct_timeout_list, head) {
 342                 if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 343                         continue;
 344
 345                 ret = ctnl_timeout_try_del(net, cur);
 346                 if (ret < 0)
 347                         return ret;
 348
 349                 break;
 350         }
 351         return ret;
 352 }
 353
 354 static int cttimeout_default_set(struct net *net, struct sock *ctnl,
 355                                  struct sk_buff *skb,
 356                                  const struct nlmsghdr *nlh,
 357                                  const struct nlattr * const cda[],
 358                                  struct netlink_ext_ack *extack)
 359 {
 360         const struct nf_conntrack_l4proto *l4proto;
 361         __u16 l3num;
 362         __u8 l4num;
 363         int ret;
 364
 365         if (!cda[CTA_TIMEOUT_L3PROTO] ||
 366             !cda[CTA_TIMEOUT_L4PROTO] ||
 367             !cda[CTA_TIMEOUT_DATA])
 368                 return -EINVAL;
 369
 370         l3num = ntohs(nla_get_be16(cda[CTA_TIMEOUT_L3PROTO]));
 371         l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]);
 372         l4proto = nf_ct_l4proto_find_get(l3num, l4num);
 373
 374         /* This protocol is not supported, skip. */
 375         if (l4proto->l4proto != l4num) {
 376                 ret = -EOPNOTSUPP;
 377                 goto err;
 378         }
 379
 380         ret = ctnl_timeout_parse_policy(NULL, l4proto, net,
 381                                         cda[CTA_TIMEOUT_DATA]);
 382         if (ret < 0)
 383                 goto err;
 384
 385         nf_ct_l4proto_put(l4proto);
 386         return 0;
 387 err:
 388         nf_ct_l4proto_put(l4proto);
 389         return ret;
 390 }
 391
 392 static int
 393 cttimeout_default_fill_info(struct net *net, struct sk_buff *skb, u32 portid,
 394                             u32 seq, u32 type, int event,
 395                             const struct nf_conntrack_l4proto *l4proto)
 396 {
 397         struct nlmsghdr *nlh;
 398         struct nfgenmsg *nfmsg;
 399         unsigned int flags = portid ? NLM_F_MULTI : 0;
 400
 401         event = nfnl_msg_type(NFNL_SUBSYS_CTNETLINK_TIMEOUT, event);
 402         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 403         if (nlh == NULL)
 404                 goto nlmsg_failure;
 405
 406         nfmsg = nlmsg_data(nlh);
 407         nfmsg->nfgen_family = AF_UNSPEC;
 408         nfmsg->version = NFNETLINK_V0;
 409         nfmsg->res_id = 0;
 410
 411         if (nla_put_be16(skb, CTA_TIMEOUT_L3PROTO, htons(l4proto->l3proto)) ||
 412             nla_put_u8(skb, CTA_TIMEOUT_L4PROTO, l4proto->l4proto))
 413                 goto nla_put_failure;
 414
 415         if (likely(l4proto->ctnl_timeout.obj_to_nlattr)) {
 416                 struct nlattr *nest_parms;
 417                 int ret;
 418
 419                 nest_parms = nla_nest_start(skb,
 420                                             CTA_TIMEOUT_DATA | NLA_F_NESTED);
 421                 if (!nest_parms)
 422                         goto nla_put_failure;
 423
 424                 ret = l4proto->ctnl_timeout.obj_to_nlattr(skb, NULL);
 425                 if (ret < 0)
 426                         goto nla_put_failure;
 427
 428                 nla_nest_end(skb, nest_parms);
 429         }
 430
 431         nlmsg_end(skb, nlh);
 432         return skb->len;
 433
 434 nlmsg_failure:
 435 nla_put_failure:
 436         nlmsg_cancel(skb, nlh);
 437         return -1;
 438 }
 439
 440 static int cttimeout_default_get(struct net *net, struct sock *ctnl,
 441                                  struct sk_buff *skb,
 442                                  const struct nlmsghdr *nlh,
 443                                  const struct nlattr * const cda[],
 444                                  struct netlink_ext_ack *extack)
 445 {
 446         const struct nf_conntrack_l4proto *l4proto;
 447         struct sk_buff *skb2;
 448         int ret, err;
 449         __u16 l3num;
 450         __u8 l4num;
 451
 452         if (!cda[CTA_TIMEOUT_L3PROTO] || !cda[CTA_TIMEOUT_L4PROTO])
 453                 return -EINVAL;
 454
 455         l3num = ntohs(nla_get_be16(cda[CTA_TIMEOUT_L3PROTO]));
 456         l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]);
 457         l4proto = nf_ct_l4proto_find_get(l3num, l4num);
 458
 459         /* This protocol is not supported, skip. */
 460         if (l4proto->l4proto != l4num) {
 461                 err = -EOPNOTSUPP;
 462                 goto err;
 463         }
 464
 465         skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 466         if (skb2 == NULL) {
 467                 err = -ENOMEM;
 468                 goto err;
 469         }
 470
 471         ret = cttimeout_default_fill_info(net, skb2, NETLINK_CB(skb).portid,
 472                                           nlh->nlmsg_seq,
 473                                           NFNL_MSG_TYPE(nlh->nlmsg_type),
 474                                           IPCTNL_MSG_TIMEOUT_DEFAULT_SET,
 475                                           l4proto);
 476         if (ret <= 0) {
 477                 kfree_skb(skb2);
 478                 err = -ENOMEM;
 479                 goto err;
 480         }
 481         ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).portid, MSG_DONTWAIT);
 482         if (ret > 0)
 483                 ret = 0;
 484
 485         /* this avoids a loop in nfnetlink. */
 486         return ret == -EAGAIN ? -ENOBUFS : ret;
 487 err:
 488         nf_ct_l4proto_put(l4proto);
 489         return err;
 490 }
 491
 492 static struct nf_ct_timeout *ctnl_timeout_find_get(struct net *net,
 493                                                    const char *name)
 494 {
 495         struct ctnl_timeout *timeout, *matching = NULL;
 496
 497         list_for_each_entry_rcu(timeout, &net->nfct_timeout_list, head) {
 498                 if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 499                         continue;
 500
 501                 if (!try_module_get(THIS_MODULE))
 502                         goto err;
 503
 504                 if (!refcount_inc_not_zero(&timeout->refcnt)) {
 505                         module_put(THIS_MODULE);
 506                         goto err;
 507                 }
 508                 matching = timeout;
 509                 break;
 510         }
 511 err:
 512         return matching ? &matching->timeout : NULL;
 513 }
 514
 515 static void ctnl_timeout_put(struct nf_ct_timeout *t)
 516 {
 517         struct ctnl_timeout *timeout =
 518                 container_of(t, struct ctnl_timeout, timeout);
 519
 520         if (refcount_dec_and_test(&timeout->refcnt))
 521                 kfree_rcu(timeout, rcu_head);
 522
 523         module_put(THIS_MODULE);
 524 }
 525
 526 static const struct nfnl_callback cttimeout_cb[IPCTNL_MSG_TIMEOUT_MAX] = {
 527         [IPCTNL_MSG_TIMEOUT_NEW]        = { .call = cttimeout_new_timeout,
 528                                             .attr_count = CTA_TIMEOUT_MAX,
 529                                             .policy = cttimeout_nla_policy },
 530         [IPCTNL_MSG_TIMEOUT_GET]        = { .call = cttimeout_get_timeout,
 531                                             .attr_count = CTA_TIMEOUT_MAX,
 532                                             .policy = cttimeout_nla_policy },
 533         [IPCTNL_MSG_TIMEOUT_DELETE]     = { .call = cttimeout_del_timeout,
 534                                             .attr_count = CTA_TIMEOUT_MAX,
 535                                             .policy = cttimeout_nla_policy },
 536         [IPCTNL_MSG_TIMEOUT_DEFAULT_SET]= { .call = cttimeout_default_set,
 537                                             .attr_count = CTA_TIMEOUT_MAX,
 538                                             .policy = cttimeout_nla_policy },
 539         [IPCTNL_MSG_TIMEOUT_DEFAULT_GET]= { .call = cttimeout_default_get,
 540                                             .attr_count = CTA_TIMEOUT_MAX,
 541                                             .policy = cttimeout_nla_policy },
 542 };
 543
 544 static const struct nfnetlink_subsystem cttimeout_subsys = {
 545         .name                           = "conntrack_timeout",
 546         .subsys_id                      = NFNL_SUBSYS_CTNETLINK_TIMEOUT,
 547         .cb_count                       = IPCTNL_MSG_TIMEOUT_MAX,
 548         .cb                             = cttimeout_cb,
 549 };
 550
 551 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTNETLINK_TIMEOUT);
 552
 553 static int __net_init cttimeout_net_init(struct net *net)
 554 {
 555         INIT_LIST_HEAD(&net->nfct_timeout_list);
 556
 557         return 0;
 558 }
 559
 560 static void __net_exit cttimeout_net_exit(struct net *net)
 561 {
 562         struct ctnl_timeout *cur, *tmp;
 563
 564         nf_ct_unconfirmed_destroy(net);
 565         nf_ct_untimeout(net, NULL);
 566
 567         list_for_each_entry_safe(cur, tmp, &net->nfct_timeout_list, head) {
 568                 list_del_rcu(&cur->head);
 569                 nf_ct_l4proto_put(cur->timeout.l4proto);
 570
 571                 if (refcount_dec_and_test(&cur->refcnt))
 572                         kfree_rcu(cur, rcu_head);
 573         }
 574 }
 575
 576 static struct pernet_operations cttimeout_ops = {
 577         .init   = cttimeout_net_init,
 578         .exit   = cttimeout_net_exit,
 579 };
 580
 581 static int __init cttimeout_init(void)
 582 {
 583         int ret;
 584
 585         ret = register_pernet_subsys(&cttimeout_ops);
 586         if (ret < 0)
 587                 return ret;
 588
 589         ret = nfnetlink_subsys_register(&cttimeout_subsys);
 590         if (ret < 0) {
 591                 pr_err("cttimeout_init: cannot register cttimeout with "
 592                         "nfnetlink.\n");
 593                 goto err_out;
 594         }
 595         RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, ctnl_timeout_find_get);
 596         RCU_INIT_POINTER(nf_ct_timeout_put_hook, ctnl_timeout_put);
 597         return 0;
 598
 599 err_out:
 600         unregister_pernet_subsys(&cttimeout_ops);
 601         return ret;
 602 }
 603
 604 static void __exit cttimeout_exit(void)
 605 {
 606         nfnetlink_subsys_unregister(&cttimeout_subsys);
 607
 608         unregister_pernet_subsys(&cttimeout_ops);
 609         RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, NULL);
 610         RCU_INIT_POINTER(nf_ct_timeout_put_hook, NULL);
 611         synchronize_rcu();
 612 }
 613
 614 module_init(cttimeout_init);
 615 module_exit(cttimeout_exit);