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_l3proto.h> 30 #include <net/netfilter/nf_conntrack_l4proto.h> 31 #include <net/netfilter/nf_conntrack_tuple.h> 32 #include <net/netfilter/nf_conntrack_timeout.h> 33 34 #include <linux/netfilter/nfnetlink.h> 35 #include <linux/netfilter/nfnetlink_cttimeout.h> 36 37 MODULE_LICENSE("GPL"); 38 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>"); 39 MODULE_DESCRIPTION("cttimeout: Extended Netfilter Connection Tracking timeout tuning"); 40 41 static const struct nla_policy cttimeout_nla_policy[CTA_TIMEOUT_MAX+1] = { 42 [CTA_TIMEOUT_NAME] = { .type = NLA_NUL_STRING, 43 .len = CTNL_TIMEOUT_NAME_MAX - 1}, 44 [CTA_TIMEOUT_L3PROTO] = { .type = NLA_U16 }, 45 [CTA_TIMEOUT_L4PROTO] = { .type = NLA_U8 }, 46 [CTA_TIMEOUT_DATA] = { .type = NLA_NESTED }, 47 }; 48 49 static int 50 ctnl_timeout_parse_policy(void *timeouts, struct nf_conntrack_l4proto *l4proto, 51 struct net *net, const struct nlattr *attr) 52 { 53 int ret = 0; 54 55 if (likely(l4proto->ctnl_timeout.nlattr_to_obj)) { 56 struct nlattr *tb[l4proto->ctnl_timeout.nlattr_max+1]; 57 58 ret = nla_parse_nested(tb, l4proto->ctnl_timeout.nlattr_max, 59 attr, l4proto->ctnl_timeout.nla_policy); 60 if (ret < 0) 61 return ret; 62 63 ret = l4proto->ctnl_timeout.nlattr_to_obj(tb, net, timeouts); 64 } 65 return ret; 66 } 67 68 static int cttimeout_new_timeout(struct net *net, struct sock *ctnl, 69 struct sk_buff *skb, 70 const struct nlmsghdr *nlh, 71 const struct nlattr * const cda[]) 72 { 73 __u16 l3num; 74 __u8 l4num; 75 struct nf_conntrack_l4proto *l4proto; 76 struct ctnl_timeout *timeout, *matching = NULL; 77 char *name; 78 int ret; 79 80 if (!cda[CTA_TIMEOUT_NAME] || 81 !cda[CTA_TIMEOUT_L3PROTO] || 82 !cda[CTA_TIMEOUT_L4PROTO] || 83 !cda[CTA_TIMEOUT_DATA]) 84 return -EINVAL; 85 86 name = nla_data(cda[CTA_TIMEOUT_NAME]); 87 l3num = ntohs(nla_get_be16(cda[CTA_TIMEOUT_L3PROTO])); 88 l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]); 89 90 list_for_each_entry(timeout, &net->nfct_timeout_list, head) { 91 if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0) 92 continue; 93 94 if (nlh->nlmsg_flags & NLM_F_EXCL) 95 return -EEXIST; 96 97 matching = timeout; 98 break; 99 } 100 101 l4proto = nf_ct_l4proto_find_get(l3num, l4num); 102 103 /* This protocol is not supportted, skip. */ 104 if (l4proto->l4proto != l4num) { 105 ret = -EOPNOTSUPP; 106 goto err_proto_put; 107 } 108 109 if (matching) { 110 if (nlh->nlmsg_flags & NLM_F_REPLACE) { 111 /* You cannot replace one timeout policy by another of 112 * different kind, sorry. 113 */ 114 if (matching->l3num != l3num || 115 matching->l4proto->l4proto != l4num) { 116 ret = -EINVAL; 117 goto err_proto_put; 118 } 119 120 ret = ctnl_timeout_parse_policy(&matching->data, 121 l4proto, net, 122 cda[CTA_TIMEOUT_DATA]); 123 return ret; 124 } 125 ret = -EBUSY; 126 goto err_proto_put; 127 } 128 129 timeout = kzalloc(sizeof(struct ctnl_timeout) + 130 l4proto->ctnl_timeout.obj_size, GFP_KERNEL); 131 if (timeout == NULL) { 132 ret = -ENOMEM; 133 goto err_proto_put; 134 } 135 136 ret = ctnl_timeout_parse_policy(&timeout->data, l4proto, net, 137 cda[CTA_TIMEOUT_DATA]); 138 if (ret < 0) 139 goto err; 140 141 strcpy(timeout->name, nla_data(cda[CTA_TIMEOUT_NAME])); 142 timeout->l3num = l3num; 143 timeout->l4proto = l4proto; 144 atomic_set(&timeout->refcnt, 1); 145 list_add_tail_rcu(&timeout->head, &net->nfct_timeout_list); 146 147 return 0; 148 err: 149 kfree(timeout); 150 err_proto_put: 151 nf_ct_l4proto_put(l4proto); 152 return ret; 153 } 154 155 static int 156 ctnl_timeout_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type, 157 int event, struct ctnl_timeout *timeout) 158 { 159 struct nlmsghdr *nlh; 160 struct nfgenmsg *nfmsg; 161 unsigned int flags = portid ? NLM_F_MULTI : 0; 162 struct nf_conntrack_l4proto *l4proto = timeout->l4proto; 163 164 event |= NFNL_SUBSYS_CTNETLINK_TIMEOUT << 8; 165 nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags); 166 if (nlh == NULL) 167 goto nlmsg_failure; 168 169 nfmsg = nlmsg_data(nlh); 170 nfmsg->nfgen_family = AF_UNSPEC; 171 nfmsg->version = NFNETLINK_V0; 172 nfmsg->res_id = 0; 173 174 if (nla_put_string(skb, CTA_TIMEOUT_NAME, timeout->name) || 175 nla_put_be16(skb, CTA_TIMEOUT_L3PROTO, htons(timeout->l3num)) || 176 nla_put_u8(skb, CTA_TIMEOUT_L4PROTO, timeout->l4proto->l4proto) || 177 nla_put_be32(skb, CTA_TIMEOUT_USE, 178 htonl(atomic_read(&timeout->refcnt)))) 179 goto nla_put_failure; 180 181 if (likely(l4proto->ctnl_timeout.obj_to_nlattr)) { 182 struct nlattr *nest_parms; 183 int ret; 184 185 nest_parms = nla_nest_start(skb, 186 CTA_TIMEOUT_DATA | NLA_F_NESTED); 187 if (!nest_parms) 188 goto nla_put_failure; 189 190 ret = l4proto->ctnl_timeout.obj_to_nlattr(skb, &timeout->data); 191 if (ret < 0) 192 goto nla_put_failure; 193 194 nla_nest_end(skb, nest_parms); 195 } 196 197 nlmsg_end(skb, nlh); 198 return skb->len; 199 200 nlmsg_failure: 201 nla_put_failure: 202 nlmsg_cancel(skb, nlh); 203 return -1; 204 } 205 206 static int 207 ctnl_timeout_dump(struct sk_buff *skb, struct netlink_callback *cb) 208 { 209 struct net *net = sock_net(skb->sk); 210 struct ctnl_timeout *cur, *last; 211 212 if (cb->args[2]) 213 return 0; 214 215 last = (struct ctnl_timeout *)cb->args[1]; 216 if (cb->args[1]) 217 cb->args[1] = 0; 218 219 rcu_read_lock(); 220 list_for_each_entry_rcu(cur, &net->nfct_timeout_list, head) { 221 if (last) { 222 if (cur != last) 223 continue; 224 225 last = NULL; 226 } 227 if (ctnl_timeout_fill_info(skb, NETLINK_CB(cb->skb).portid, 228 cb->nlh->nlmsg_seq, 229 NFNL_MSG_TYPE(cb->nlh->nlmsg_type), 230 IPCTNL_MSG_TIMEOUT_NEW, cur) < 0) { 231 cb->args[1] = (unsigned long)cur; 232 break; 233 } 234 } 235 if (!cb->args[1]) 236 cb->args[2] = 1; 237 rcu_read_unlock(); 238 return skb->len; 239 } 240 241 static int cttimeout_get_timeout(struct net *net, struct sock *ctnl, 242 struct sk_buff *skb, 243 const struct nlmsghdr *nlh, 244 const struct nlattr * const cda[]) 245 { 246 int ret = -ENOENT; 247 char *name; 248 struct ctnl_timeout *cur; 249 250 if (nlh->nlmsg_flags & NLM_F_DUMP) { 251 struct netlink_dump_control c = { 252 .dump = ctnl_timeout_dump, 253 }; 254 return netlink_dump_start(ctnl, skb, nlh, &c); 255 } 256 257 if (!cda[CTA_TIMEOUT_NAME]) 258 return -EINVAL; 259 name = nla_data(cda[CTA_TIMEOUT_NAME]); 260 261 list_for_each_entry(cur, &net->nfct_timeout_list, head) { 262 struct sk_buff *skb2; 263 264 if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0) 265 continue; 266 267 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL); 268 if (skb2 == NULL) { 269 ret = -ENOMEM; 270 break; 271 } 272 273 ret = ctnl_timeout_fill_info(skb2, NETLINK_CB(skb).portid, 274 nlh->nlmsg_seq, 275 NFNL_MSG_TYPE(nlh->nlmsg_type), 276 IPCTNL_MSG_TIMEOUT_NEW, cur); 277 if (ret <= 0) { 278 kfree_skb(skb2); 279 break; 280 } 281 ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).portid, 282 MSG_DONTWAIT); 283 if (ret > 0) 284 ret = 0; 285 286 /* this avoids a loop in nfnetlink. */ 287 return ret == -EAGAIN ? -ENOBUFS : ret; 288 } 289 return ret; 290 } 291 292 static void untimeout(struct nf_conntrack_tuple_hash *i, 293 struct ctnl_timeout *timeout) 294 { 295 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i); 296 struct nf_conn_timeout *timeout_ext = nf_ct_timeout_find(ct); 297 298 if (timeout_ext && (!timeout || timeout_ext->timeout == timeout)) 299 RCU_INIT_POINTER(timeout_ext->timeout, NULL); 300 } 301 302 static void ctnl_untimeout(struct net *net, struct ctnl_timeout *timeout) 303 { 304 struct nf_conntrack_tuple_hash *h; 305 const struct hlist_nulls_node *nn; 306 int i; 307 308 local_bh_disable(); 309 for (i = 0; i < nf_conntrack_htable_size; i++) { 310 nf_conntrack_lock(&nf_conntrack_locks[i % CONNTRACK_LOCKS]); 311 if (i < nf_conntrack_htable_size) { 312 hlist_nulls_for_each_entry(h, nn, &nf_conntrack_hash[i], hnnode) 313 untimeout(h, timeout); 314 } 315 spin_unlock(&nf_conntrack_locks[i % CONNTRACK_LOCKS]); 316 } 317 local_bh_enable(); 318 } 319 320 /* try to delete object, fail if it is still in use. */ 321 static int ctnl_timeout_try_del(struct net *net, struct ctnl_timeout *timeout) 322 { 323 int ret = 0; 324 325 /* we want to avoid races with nf_ct_timeout_find_get. */ 326 if (atomic_dec_and_test(&timeout->refcnt)) { 327 /* We are protected by nfnl mutex. */ 328 list_del_rcu(&timeout->head); 329 nf_ct_l4proto_put(timeout->l4proto); 330 ctnl_untimeout(net, timeout); 331 kfree_rcu(timeout, rcu_head); 332 } else { 333 /* still in use, restore reference counter. */ 334 atomic_inc(&timeout->refcnt); 335 ret = -EBUSY; 336 } 337 return ret; 338 } 339 340 static int cttimeout_del_timeout(struct net *net, struct sock *ctnl, 341 struct sk_buff *skb, 342 const struct nlmsghdr *nlh, 343 const struct nlattr * const cda[]) 344 { 345 struct ctnl_timeout *cur; 346 int ret = -ENOENT; 347 char *name; 348 349 if (!cda[CTA_TIMEOUT_NAME]) { 350 list_for_each_entry(cur, &net->nfct_timeout_list, head) 351 ctnl_timeout_try_del(net, cur); 352 353 return 0; 354 } 355 name = nla_data(cda[CTA_TIMEOUT_NAME]); 356 357 list_for_each_entry(cur, &net->nfct_timeout_list, head) { 358 if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0) 359 continue; 360 361 ret = ctnl_timeout_try_del(net, cur); 362 if (ret < 0) 363 return ret; 364 365 break; 366 } 367 return ret; 368 } 369 370 static int cttimeout_default_set(struct net *net, struct sock *ctnl, 371 struct sk_buff *skb, 372 const struct nlmsghdr *nlh, 373 const struct nlattr * const cda[]) 374 { 375 __u16 l3num; 376 __u8 l4num; 377 struct nf_conntrack_l4proto *l4proto; 378 unsigned int *timeouts; 379 int ret; 380 381 if (!cda[CTA_TIMEOUT_L3PROTO] || 382 !cda[CTA_TIMEOUT_L4PROTO] || 383 !cda[CTA_TIMEOUT_DATA]) 384 return -EINVAL; 385 386 l3num = ntohs(nla_get_be16(cda[CTA_TIMEOUT_L3PROTO])); 387 l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]); 388 l4proto = nf_ct_l4proto_find_get(l3num, l4num); 389 390 /* This protocol is not supported, skip. */ 391 if (l4proto->l4proto != l4num) { 392 ret = -EOPNOTSUPP; 393 goto err; 394 } 395 396 timeouts = l4proto->get_timeouts(net); 397 398 ret = ctnl_timeout_parse_policy(timeouts, l4proto, net, 399 cda[CTA_TIMEOUT_DATA]); 400 if (ret < 0) 401 goto err; 402 403 nf_ct_l4proto_put(l4proto); 404 return 0; 405 err: 406 nf_ct_l4proto_put(l4proto); 407 return ret; 408 } 409 410 static int 411 cttimeout_default_fill_info(struct net *net, struct sk_buff *skb, u32 portid, 412 u32 seq, u32 type, int event, 413 struct nf_conntrack_l4proto *l4proto) 414 { 415 struct nlmsghdr *nlh; 416 struct nfgenmsg *nfmsg; 417 unsigned int flags = portid ? NLM_F_MULTI : 0; 418 419 event |= NFNL_SUBSYS_CTNETLINK_TIMEOUT << 8; 420 nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags); 421 if (nlh == NULL) 422 goto nlmsg_failure; 423 424 nfmsg = nlmsg_data(nlh); 425 nfmsg->nfgen_family = AF_UNSPEC; 426 nfmsg->version = NFNETLINK_V0; 427 nfmsg->res_id = 0; 428 429 if (nla_put_be16(skb, CTA_TIMEOUT_L3PROTO, htons(l4proto->l3proto)) || 430 nla_put_u8(skb, CTA_TIMEOUT_L4PROTO, l4proto->l4proto)) 431 goto nla_put_failure; 432 433 if (likely(l4proto->ctnl_timeout.obj_to_nlattr)) { 434 struct nlattr *nest_parms; 435 unsigned int *timeouts = l4proto->get_timeouts(net); 436 int ret; 437 438 nest_parms = nla_nest_start(skb, 439 CTA_TIMEOUT_DATA | NLA_F_NESTED); 440 if (!nest_parms) 441 goto nla_put_failure; 442 443 ret = l4proto->ctnl_timeout.obj_to_nlattr(skb, timeouts); 444 if (ret < 0) 445 goto nla_put_failure; 446 447 nla_nest_end(skb, nest_parms); 448 } 449 450 nlmsg_end(skb, nlh); 451 return skb->len; 452 453 nlmsg_failure: 454 nla_put_failure: 455 nlmsg_cancel(skb, nlh); 456 return -1; 457 } 458 459 static int cttimeout_default_get(struct net *net, struct sock *ctnl, 460 struct sk_buff *skb, 461 const struct nlmsghdr *nlh, 462 const struct nlattr * const cda[]) 463 { 464 __u16 l3num; 465 __u8 l4num; 466 struct nf_conntrack_l4proto *l4proto; 467 struct sk_buff *skb2; 468 int ret, err; 469 470 if (!cda[CTA_TIMEOUT_L3PROTO] || !cda[CTA_TIMEOUT_L4PROTO]) 471 return -EINVAL; 472 473 l3num = ntohs(nla_get_be16(cda[CTA_TIMEOUT_L3PROTO])); 474 l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]); 475 l4proto = nf_ct_l4proto_find_get(l3num, l4num); 476 477 /* This protocol is not supported, skip. */ 478 if (l4proto->l4proto != l4num) { 479 err = -EOPNOTSUPP; 480 goto err; 481 } 482 483 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL); 484 if (skb2 == NULL) { 485 err = -ENOMEM; 486 goto err; 487 } 488 489 ret = cttimeout_default_fill_info(net, skb2, NETLINK_CB(skb).portid, 490 nlh->nlmsg_seq, 491 NFNL_MSG_TYPE(nlh->nlmsg_type), 492 IPCTNL_MSG_TIMEOUT_DEFAULT_SET, 493 l4proto); 494 if (ret <= 0) { 495 kfree_skb(skb2); 496 err = -ENOMEM; 497 goto err; 498 } 499 ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).portid, MSG_DONTWAIT); 500 if (ret > 0) 501 ret = 0; 502 503 /* this avoids a loop in nfnetlink. */ 504 return ret == -EAGAIN ? -ENOBUFS : ret; 505 err: 506 nf_ct_l4proto_put(l4proto); 507 return err; 508 } 509 510 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT 511 static struct ctnl_timeout * 512 ctnl_timeout_find_get(struct net *net, const char *name) 513 { 514 struct ctnl_timeout *timeout, *matching = NULL; 515 516 rcu_read_lock(); 517 list_for_each_entry_rcu(timeout, &net->nfct_timeout_list, head) { 518 if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0) 519 continue; 520 521 if (!try_module_get(THIS_MODULE)) 522 goto err; 523 524 if (!atomic_inc_not_zero(&timeout->refcnt)) { 525 module_put(THIS_MODULE); 526 goto err; 527 } 528 matching = timeout; 529 break; 530 } 531 err: 532 rcu_read_unlock(); 533 return matching; 534 } 535 536 static void ctnl_timeout_put(struct ctnl_timeout *timeout) 537 { 538 atomic_dec(&timeout->refcnt); 539 module_put(THIS_MODULE); 540 } 541 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ 542 543 static const struct nfnl_callback cttimeout_cb[IPCTNL_MSG_TIMEOUT_MAX] = { 544 [IPCTNL_MSG_TIMEOUT_NEW] = { .call = cttimeout_new_timeout, 545 .attr_count = CTA_TIMEOUT_MAX, 546 .policy = cttimeout_nla_policy }, 547 [IPCTNL_MSG_TIMEOUT_GET] = { .call = cttimeout_get_timeout, 548 .attr_count = CTA_TIMEOUT_MAX, 549 .policy = cttimeout_nla_policy }, 550 [IPCTNL_MSG_TIMEOUT_DELETE] = { .call = cttimeout_del_timeout, 551 .attr_count = CTA_TIMEOUT_MAX, 552 .policy = cttimeout_nla_policy }, 553 [IPCTNL_MSG_TIMEOUT_DEFAULT_SET]= { .call = cttimeout_default_set, 554 .attr_count = CTA_TIMEOUT_MAX, 555 .policy = cttimeout_nla_policy }, 556 [IPCTNL_MSG_TIMEOUT_DEFAULT_GET]= { .call = cttimeout_default_get, 557 .attr_count = CTA_TIMEOUT_MAX, 558 .policy = cttimeout_nla_policy }, 559 }; 560 561 static const struct nfnetlink_subsystem cttimeout_subsys = { 562 .name = "conntrack_timeout", 563 .subsys_id = NFNL_SUBSYS_CTNETLINK_TIMEOUT, 564 .cb_count = IPCTNL_MSG_TIMEOUT_MAX, 565 .cb = cttimeout_cb, 566 }; 567 568 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTNETLINK_TIMEOUT); 569 570 static int __net_init cttimeout_net_init(struct net *net) 571 { 572 INIT_LIST_HEAD(&net->nfct_timeout_list); 573 574 return 0; 575 } 576 577 static void __net_exit cttimeout_net_exit(struct net *net) 578 { 579 struct ctnl_timeout *cur, *tmp; 580 581 ctnl_untimeout(net, NULL); 582 583 list_for_each_entry_safe(cur, tmp, &net->nfct_timeout_list, head) { 584 list_del_rcu(&cur->head); 585 nf_ct_l4proto_put(cur->l4proto); 586 kfree_rcu(cur, rcu_head); 587 } 588 } 589 590 static struct pernet_operations cttimeout_ops = { 591 .init = cttimeout_net_init, 592 .exit = cttimeout_net_exit, 593 }; 594 595 static int __init cttimeout_init(void) 596 { 597 int ret; 598 599 ret = register_pernet_subsys(&cttimeout_ops); 600 if (ret < 0) 601 return ret; 602 603 ret = nfnetlink_subsys_register(&cttimeout_subsys); 604 if (ret < 0) { 605 pr_err("cttimeout_init: cannot register cttimeout with " 606 "nfnetlink.\n"); 607 goto err_out; 608 } 609 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT 610 RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, ctnl_timeout_find_get); 611 RCU_INIT_POINTER(nf_ct_timeout_put_hook, ctnl_timeout_put); 612 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ 613 return 0; 614 615 err_out: 616 unregister_pernet_subsys(&cttimeout_ops); 617 return ret; 618 } 619 620 static void __exit cttimeout_exit(void) 621 { 622 pr_info("cttimeout: unregistering from nfnetlink.\n"); 623 624 nfnetlink_subsys_unregister(&cttimeout_subsys); 625 626 unregister_pernet_subsys(&cttimeout_ops); 627 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT 628 RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, NULL); 629 RCU_INIT_POINTER(nf_ct_timeout_put_hook, NULL); 630 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ 631 rcu_barrier(); 632 } 633 634 module_init(cttimeout_init); 635 module_exit(cttimeout_exit); 636