nf_conntrack_core.c revision d8a0509a696de60296a66ba4fe4f9eaade497103
1/* Connection state tracking for netfilter. This is separated from, 2 but required by, the NAT layer; it can also be used by an iptables 3 extension. */ 4 5/* (C) 1999-2001 Paul `Rusty' Russell 6 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> 7 * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License version 2 as 11 * published by the Free Software Foundation. 12 */ 13 14#include <linux/types.h> 15#include <linux/netfilter.h> 16#include <linux/module.h> 17#include <linux/skbuff.h> 18#include <linux/proc_fs.h> 19#include <linux/vmalloc.h> 20#include <linux/stddef.h> 21#include <linux/slab.h> 22#include <linux/random.h> 23#include <linux/jhash.h> 24#include <linux/err.h> 25#include <linux/percpu.h> 26#include <linux/moduleparam.h> 27#include <linux/notifier.h> 28#include <linux/kernel.h> 29#include <linux/netdevice.h> 30#include <linux/socket.h> 31#include <linux/mm.h> 32 33#include <net/netfilter/nf_conntrack.h> 34#include <net/netfilter/nf_conntrack_l3proto.h> 35#include <net/netfilter/nf_conntrack_l4proto.h> 36#include <net/netfilter/nf_conntrack_expect.h> 37#include <net/netfilter/nf_conntrack_helper.h> 38#include <net/netfilter/nf_conntrack_core.h> 39#include <net/netfilter/nf_conntrack_extend.h> 40 41#define NF_CONNTRACK_VERSION "0.5.0" 42 43#if 0 44#define DEBUGP printk 45#else 46#define DEBUGP(format, args...) 47#endif 48 49DEFINE_RWLOCK(nf_conntrack_lock); 50EXPORT_SYMBOL_GPL(nf_conntrack_lock); 51 52/* nf_conntrack_standalone needs this */ 53atomic_t nf_conntrack_count = ATOMIC_INIT(0); 54EXPORT_SYMBOL_GPL(nf_conntrack_count); 55 56unsigned int nf_conntrack_htable_size __read_mostly; 57EXPORT_SYMBOL_GPL(nf_conntrack_htable_size); 58 59int nf_conntrack_max __read_mostly; 60EXPORT_SYMBOL_GPL(nf_conntrack_max); 61 62struct list_head *nf_conntrack_hash __read_mostly; 63EXPORT_SYMBOL_GPL(nf_conntrack_hash); 64 65struct nf_conn nf_conntrack_untracked __read_mostly; 66EXPORT_SYMBOL_GPL(nf_conntrack_untracked); 67 68unsigned int nf_ct_log_invalid __read_mostly; 69LIST_HEAD(unconfirmed); 70static int nf_conntrack_vmalloc __read_mostly; 71static struct kmem_cache *nf_conntrack_cachep __read_mostly; 72static unsigned int nf_conntrack_next_id; 73 74DEFINE_PER_CPU(struct ip_conntrack_stat, nf_conntrack_stat); 75EXPORT_PER_CPU_SYMBOL(nf_conntrack_stat); 76 77static int nf_conntrack_hash_rnd_initted; 78static unsigned int nf_conntrack_hash_rnd; 79 80static u_int32_t __hash_conntrack(const struct nf_conntrack_tuple *tuple, 81 unsigned int size, unsigned int rnd) 82{ 83 unsigned int a, b; 84 85 a = jhash2(tuple->src.u3.all, ARRAY_SIZE(tuple->src.u3.all), 86 (tuple->src.l3num << 16) | tuple->dst.protonum); 87 b = jhash2(tuple->dst.u3.all, ARRAY_SIZE(tuple->dst.u3.all), 88 (tuple->src.u.all << 16) | tuple->dst.u.all); 89 90 return jhash_2words(a, b, rnd) % size; 91} 92 93static inline u_int32_t hash_conntrack(const struct nf_conntrack_tuple *tuple) 94{ 95 return __hash_conntrack(tuple, nf_conntrack_htable_size, 96 nf_conntrack_hash_rnd); 97} 98 99int 100nf_ct_get_tuple(const struct sk_buff *skb, 101 unsigned int nhoff, 102 unsigned int dataoff, 103 u_int16_t l3num, 104 u_int8_t protonum, 105 struct nf_conntrack_tuple *tuple, 106 const struct nf_conntrack_l3proto *l3proto, 107 const struct nf_conntrack_l4proto *l4proto) 108{ 109 NF_CT_TUPLE_U_BLANK(tuple); 110 111 tuple->src.l3num = l3num; 112 if (l3proto->pkt_to_tuple(skb, nhoff, tuple) == 0) 113 return 0; 114 115 tuple->dst.protonum = protonum; 116 tuple->dst.dir = IP_CT_DIR_ORIGINAL; 117 118 return l4proto->pkt_to_tuple(skb, dataoff, tuple); 119} 120EXPORT_SYMBOL_GPL(nf_ct_get_tuple); 121 122int 123nf_ct_invert_tuple(struct nf_conntrack_tuple *inverse, 124 const struct nf_conntrack_tuple *orig, 125 const struct nf_conntrack_l3proto *l3proto, 126 const struct nf_conntrack_l4proto *l4proto) 127{ 128 NF_CT_TUPLE_U_BLANK(inverse); 129 130 inverse->src.l3num = orig->src.l3num; 131 if (l3proto->invert_tuple(inverse, orig) == 0) 132 return 0; 133 134 inverse->dst.dir = !orig->dst.dir; 135 136 inverse->dst.protonum = orig->dst.protonum; 137 return l4proto->invert_tuple(inverse, orig); 138} 139EXPORT_SYMBOL_GPL(nf_ct_invert_tuple); 140 141static void 142clean_from_lists(struct nf_conn *ct) 143{ 144 DEBUGP("clean_from_lists(%p)\n", ct); 145 list_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].list); 146 list_del(&ct->tuplehash[IP_CT_DIR_REPLY].list); 147 148 /* Destroy all pending expectations */ 149 nf_ct_remove_expectations(ct); 150} 151 152static void 153destroy_conntrack(struct nf_conntrack *nfct) 154{ 155 struct nf_conn *ct = (struct nf_conn *)nfct; 156 struct nf_conntrack_l4proto *l4proto; 157 158 DEBUGP("destroy_conntrack(%p)\n", ct); 159 NF_CT_ASSERT(atomic_read(&nfct->use) == 0); 160 NF_CT_ASSERT(!timer_pending(&ct->timeout)); 161 162 nf_conntrack_event(IPCT_DESTROY, ct); 163 set_bit(IPS_DYING_BIT, &ct->status); 164 165 /* To make sure we don't get any weird locking issues here: 166 * destroy_conntrack() MUST NOT be called with a write lock 167 * to nf_conntrack_lock!!! -HW */ 168 rcu_read_lock(); 169 l4proto = __nf_ct_l4proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.l3num, 170 ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum); 171 if (l4proto && l4proto->destroy) 172 l4proto->destroy(ct); 173 174 nf_ct_ext_destroy(ct); 175 176 rcu_read_unlock(); 177 178 write_lock_bh(&nf_conntrack_lock); 179 /* Expectations will have been removed in clean_from_lists, 180 * except TFTP can create an expectation on the first packet, 181 * before connection is in the list, so we need to clean here, 182 * too. */ 183 nf_ct_remove_expectations(ct); 184 185 /* We overload first tuple to link into unconfirmed list. */ 186 if (!nf_ct_is_confirmed(ct)) { 187 BUG_ON(list_empty(&ct->tuplehash[IP_CT_DIR_ORIGINAL].list)); 188 list_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].list); 189 } 190 191 NF_CT_STAT_INC(delete); 192 write_unlock_bh(&nf_conntrack_lock); 193 194 if (ct->master) 195 nf_ct_put(ct->master); 196 197 DEBUGP("destroy_conntrack: returning ct=%p to slab\n", ct); 198 nf_conntrack_free(ct); 199} 200 201static void death_by_timeout(unsigned long ul_conntrack) 202{ 203 struct nf_conn *ct = (void *)ul_conntrack; 204 struct nf_conn_help *help = nfct_help(ct); 205 struct nf_conntrack_helper *helper; 206 207 if (help) { 208 rcu_read_lock(); 209 helper = rcu_dereference(help->helper); 210 if (helper && helper->destroy) 211 helper->destroy(ct); 212 rcu_read_unlock(); 213 } 214 215 write_lock_bh(&nf_conntrack_lock); 216 /* Inside lock so preempt is disabled on module removal path. 217 * Otherwise we can get spurious warnings. */ 218 NF_CT_STAT_INC(delete_list); 219 clean_from_lists(ct); 220 write_unlock_bh(&nf_conntrack_lock); 221 nf_ct_put(ct); 222} 223 224struct nf_conntrack_tuple_hash * 225__nf_conntrack_find(const struct nf_conntrack_tuple *tuple, 226 const struct nf_conn *ignored_conntrack) 227{ 228 struct nf_conntrack_tuple_hash *h; 229 unsigned int hash = hash_conntrack(tuple); 230 231 list_for_each_entry(h, &nf_conntrack_hash[hash], list) { 232 if (nf_ct_tuplehash_to_ctrack(h) != ignored_conntrack && 233 nf_ct_tuple_equal(tuple, &h->tuple)) { 234 NF_CT_STAT_INC(found); 235 return h; 236 } 237 NF_CT_STAT_INC(searched); 238 } 239 240 return NULL; 241} 242EXPORT_SYMBOL_GPL(__nf_conntrack_find); 243 244/* Find a connection corresponding to a tuple. */ 245struct nf_conntrack_tuple_hash * 246nf_conntrack_find_get(const struct nf_conntrack_tuple *tuple, 247 const struct nf_conn *ignored_conntrack) 248{ 249 struct nf_conntrack_tuple_hash *h; 250 251 read_lock_bh(&nf_conntrack_lock); 252 h = __nf_conntrack_find(tuple, ignored_conntrack); 253 if (h) 254 atomic_inc(&nf_ct_tuplehash_to_ctrack(h)->ct_general.use); 255 read_unlock_bh(&nf_conntrack_lock); 256 257 return h; 258} 259EXPORT_SYMBOL_GPL(nf_conntrack_find_get); 260 261static void __nf_conntrack_hash_insert(struct nf_conn *ct, 262 unsigned int hash, 263 unsigned int repl_hash) 264{ 265 ct->id = ++nf_conntrack_next_id; 266 list_add(&ct->tuplehash[IP_CT_DIR_ORIGINAL].list, 267 &nf_conntrack_hash[hash]); 268 list_add(&ct->tuplehash[IP_CT_DIR_REPLY].list, 269 &nf_conntrack_hash[repl_hash]); 270} 271 272void nf_conntrack_hash_insert(struct nf_conn *ct) 273{ 274 unsigned int hash, repl_hash; 275 276 hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); 277 repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); 278 279 write_lock_bh(&nf_conntrack_lock); 280 __nf_conntrack_hash_insert(ct, hash, repl_hash); 281 write_unlock_bh(&nf_conntrack_lock); 282} 283EXPORT_SYMBOL_GPL(nf_conntrack_hash_insert); 284 285/* Confirm a connection given skb; places it in hash table */ 286int 287__nf_conntrack_confirm(struct sk_buff **pskb) 288{ 289 unsigned int hash, repl_hash; 290 struct nf_conntrack_tuple_hash *h; 291 struct nf_conn *ct; 292 struct nf_conn_help *help; 293 enum ip_conntrack_info ctinfo; 294 295 ct = nf_ct_get(*pskb, &ctinfo); 296 297 /* ipt_REJECT uses nf_conntrack_attach to attach related 298 ICMP/TCP RST packets in other direction. Actual packet 299 which created connection will be IP_CT_NEW or for an 300 expected connection, IP_CT_RELATED. */ 301 if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) 302 return NF_ACCEPT; 303 304 hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); 305 repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); 306 307 /* We're not in hash table, and we refuse to set up related 308 connections for unconfirmed conns. But packet copies and 309 REJECT will give spurious warnings here. */ 310 /* NF_CT_ASSERT(atomic_read(&ct->ct_general.use) == 1); */ 311 312 /* No external references means noone else could have 313 confirmed us. */ 314 NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); 315 DEBUGP("Confirming conntrack %p\n", ct); 316 317 write_lock_bh(&nf_conntrack_lock); 318 319 /* See if there's one in the list already, including reverse: 320 NAT could have grabbed it without realizing, since we're 321 not in the hash. If there is, we lost race. */ 322 list_for_each_entry(h, &nf_conntrack_hash[hash], list) 323 if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, 324 &h->tuple)) 325 goto out; 326 list_for_each_entry(h, &nf_conntrack_hash[repl_hash], list) 327 if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_REPLY].tuple, 328 &h->tuple)) 329 goto out; 330 331 /* Remove from unconfirmed list */ 332 list_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].list); 333 334 __nf_conntrack_hash_insert(ct, hash, repl_hash); 335 /* Timer relative to confirmation time, not original 336 setting time, otherwise we'd get timer wrap in 337 weird delay cases. */ 338 ct->timeout.expires += jiffies; 339 add_timer(&ct->timeout); 340 atomic_inc(&ct->ct_general.use); 341 set_bit(IPS_CONFIRMED_BIT, &ct->status); 342 NF_CT_STAT_INC(insert); 343 write_unlock_bh(&nf_conntrack_lock); 344 help = nfct_help(ct); 345 if (help && help->helper) 346 nf_conntrack_event_cache(IPCT_HELPER, *pskb); 347#ifdef CONFIG_NF_NAT_NEEDED 348 if (test_bit(IPS_SRC_NAT_DONE_BIT, &ct->status) || 349 test_bit(IPS_DST_NAT_DONE_BIT, &ct->status)) 350 nf_conntrack_event_cache(IPCT_NATINFO, *pskb); 351#endif 352 nf_conntrack_event_cache(master_ct(ct) ? 353 IPCT_RELATED : IPCT_NEW, *pskb); 354 return NF_ACCEPT; 355 356out: 357 NF_CT_STAT_INC(insert_failed); 358 write_unlock_bh(&nf_conntrack_lock); 359 return NF_DROP; 360} 361EXPORT_SYMBOL_GPL(__nf_conntrack_confirm); 362 363/* Returns true if a connection correspondings to the tuple (required 364 for NAT). */ 365int 366nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple, 367 const struct nf_conn *ignored_conntrack) 368{ 369 struct nf_conntrack_tuple_hash *h; 370 371 read_lock_bh(&nf_conntrack_lock); 372 h = __nf_conntrack_find(tuple, ignored_conntrack); 373 read_unlock_bh(&nf_conntrack_lock); 374 375 return h != NULL; 376} 377EXPORT_SYMBOL_GPL(nf_conntrack_tuple_taken); 378 379/* There's a small race here where we may free a just-assured 380 connection. Too bad: we're in trouble anyway. */ 381static int early_drop(struct list_head *chain) 382{ 383 /* Traverse backwards: gives us oldest, which is roughly LRU */ 384 struct nf_conntrack_tuple_hash *h; 385 struct nf_conn *ct = NULL, *tmp; 386 int dropped = 0; 387 388 read_lock_bh(&nf_conntrack_lock); 389 list_for_each_entry_reverse(h, chain, list) { 390 tmp = nf_ct_tuplehash_to_ctrack(h); 391 if (!test_bit(IPS_ASSURED_BIT, &tmp->status)) { 392 ct = tmp; 393 atomic_inc(&ct->ct_general.use); 394 break; 395 } 396 } 397 read_unlock_bh(&nf_conntrack_lock); 398 399 if (!ct) 400 return dropped; 401 402 if (del_timer(&ct->timeout)) { 403 death_by_timeout((unsigned long)ct); 404 dropped = 1; 405 NF_CT_STAT_INC_ATOMIC(early_drop); 406 } 407 nf_ct_put(ct); 408 return dropped; 409} 410 411struct nf_conn *nf_conntrack_alloc(const struct nf_conntrack_tuple *orig, 412 const struct nf_conntrack_tuple *repl) 413{ 414 struct nf_conn *conntrack = NULL; 415 416 if (unlikely(!nf_conntrack_hash_rnd_initted)) { 417 get_random_bytes(&nf_conntrack_hash_rnd, 4); 418 nf_conntrack_hash_rnd_initted = 1; 419 } 420 421 /* We don't want any race condition at early drop stage */ 422 atomic_inc(&nf_conntrack_count); 423 424 if (nf_conntrack_max 425 && atomic_read(&nf_conntrack_count) > nf_conntrack_max) { 426 unsigned int hash = hash_conntrack(orig); 427 /* Try dropping from this hash chain. */ 428 if (!early_drop(&nf_conntrack_hash[hash])) { 429 atomic_dec(&nf_conntrack_count); 430 if (net_ratelimit()) 431 printk(KERN_WARNING 432 "nf_conntrack: table full, dropping" 433 " packet.\n"); 434 return ERR_PTR(-ENOMEM); 435 } 436 } 437 438 conntrack = kmem_cache_zalloc(nf_conntrack_cachep, GFP_ATOMIC); 439 if (conntrack == NULL) { 440 DEBUGP("nf_conntrack_alloc: Can't alloc conntrack.\n"); 441 atomic_dec(&nf_conntrack_count); 442 return ERR_PTR(-ENOMEM); 443 } 444 445 atomic_set(&conntrack->ct_general.use, 1); 446 conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *orig; 447 conntrack->tuplehash[IP_CT_DIR_REPLY].tuple = *repl; 448 /* Don't set timer yet: wait for confirmation */ 449 setup_timer(&conntrack->timeout, death_by_timeout, 450 (unsigned long)conntrack); 451 452 return conntrack; 453} 454EXPORT_SYMBOL_GPL(nf_conntrack_alloc); 455 456void nf_conntrack_free(struct nf_conn *conntrack) 457{ 458 nf_ct_ext_free(conntrack); 459 kmem_cache_free(nf_conntrack_cachep, conntrack); 460 atomic_dec(&nf_conntrack_count); 461} 462EXPORT_SYMBOL_GPL(nf_conntrack_free); 463 464/* Allocate a new conntrack: we return -ENOMEM if classification 465 failed due to stress. Otherwise it really is unclassifiable. */ 466static struct nf_conntrack_tuple_hash * 467init_conntrack(const struct nf_conntrack_tuple *tuple, 468 struct nf_conntrack_l3proto *l3proto, 469 struct nf_conntrack_l4proto *l4proto, 470 struct sk_buff *skb, 471 unsigned int dataoff) 472{ 473 struct nf_conn *conntrack; 474 struct nf_conn_help *help; 475 struct nf_conntrack_tuple repl_tuple; 476 struct nf_conntrack_expect *exp; 477 478 if (!nf_ct_invert_tuple(&repl_tuple, tuple, l3proto, l4proto)) { 479 DEBUGP("Can't invert tuple.\n"); 480 return NULL; 481 } 482 483 conntrack = nf_conntrack_alloc(tuple, &repl_tuple); 484 if (conntrack == NULL || IS_ERR(conntrack)) { 485 DEBUGP("Can't allocate conntrack.\n"); 486 return (struct nf_conntrack_tuple_hash *)conntrack; 487 } 488 489 if (!l4proto->new(conntrack, skb, dataoff)) { 490 nf_conntrack_free(conntrack); 491 DEBUGP("init conntrack: can't track with proto module\n"); 492 return NULL; 493 } 494 495 write_lock_bh(&nf_conntrack_lock); 496 exp = find_expectation(tuple); 497 if (exp) { 498 DEBUGP("conntrack: expectation arrives ct=%p exp=%p\n", 499 conntrack, exp); 500 /* Welcome, Mr. Bond. We've been expecting you... */ 501 __set_bit(IPS_EXPECTED_BIT, &conntrack->status); 502 conntrack->master = exp->master; 503 if (exp->helper) { 504 help = nf_ct_ext_add(conntrack, NF_CT_EXT_HELPER, 505 GFP_ATOMIC); 506 if (help) 507 rcu_assign_pointer(help->helper, exp->helper); 508 else 509 DEBUGP("failed to add helper extension area"); 510 } 511 512#ifdef CONFIG_NF_CONNTRACK_MARK 513 conntrack->mark = exp->master->mark; 514#endif 515#ifdef CONFIG_NF_CONNTRACK_SECMARK 516 conntrack->secmark = exp->master->secmark; 517#endif 518 nf_conntrack_get(&conntrack->master->ct_general); 519 NF_CT_STAT_INC(expect_new); 520 } else { 521 struct nf_conntrack_helper *helper; 522 523 helper = __nf_ct_helper_find(&repl_tuple); 524 if (helper) { 525 help = nf_ct_ext_add(conntrack, NF_CT_EXT_HELPER, 526 GFP_ATOMIC); 527 if (help) 528 /* not in hash table yet, so not strictly 529 necessary */ 530 rcu_assign_pointer(help->helper, helper); 531 else 532 DEBUGP("failed to add helper extension area"); 533 } 534 NF_CT_STAT_INC(new); 535 } 536 537 /* Overload tuple linked list to put us in unconfirmed list. */ 538 list_add(&conntrack->tuplehash[IP_CT_DIR_ORIGINAL].list, &unconfirmed); 539 540 write_unlock_bh(&nf_conntrack_lock); 541 542 if (exp) { 543 if (exp->expectfn) 544 exp->expectfn(conntrack, exp); 545 nf_conntrack_expect_put(exp); 546 } 547 548 return &conntrack->tuplehash[IP_CT_DIR_ORIGINAL]; 549} 550 551/* On success, returns conntrack ptr, sets skb->nfct and ctinfo */ 552static inline struct nf_conn * 553resolve_normal_ct(struct sk_buff *skb, 554 unsigned int dataoff, 555 u_int16_t l3num, 556 u_int8_t protonum, 557 struct nf_conntrack_l3proto *l3proto, 558 struct nf_conntrack_l4proto *l4proto, 559 int *set_reply, 560 enum ip_conntrack_info *ctinfo) 561{ 562 struct nf_conntrack_tuple tuple; 563 struct nf_conntrack_tuple_hash *h; 564 struct nf_conn *ct; 565 566 if (!nf_ct_get_tuple(skb, skb_network_offset(skb), 567 dataoff, l3num, protonum, &tuple, l3proto, 568 l4proto)) { 569 DEBUGP("resolve_normal_ct: Can't get tuple\n"); 570 return NULL; 571 } 572 573 /* look for tuple match */ 574 h = nf_conntrack_find_get(&tuple, NULL); 575 if (!h) { 576 h = init_conntrack(&tuple, l3proto, l4proto, skb, dataoff); 577 if (!h) 578 return NULL; 579 if (IS_ERR(h)) 580 return (void *)h; 581 } 582 ct = nf_ct_tuplehash_to_ctrack(h); 583 584 /* It exists; we have (non-exclusive) reference. */ 585 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) { 586 *ctinfo = IP_CT_ESTABLISHED + IP_CT_IS_REPLY; 587 /* Please set reply bit if this packet OK */ 588 *set_reply = 1; 589 } else { 590 /* Once we've had two way comms, always ESTABLISHED. */ 591 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { 592 DEBUGP("nf_conntrack_in: normal packet for %p\n", ct); 593 *ctinfo = IP_CT_ESTABLISHED; 594 } else if (test_bit(IPS_EXPECTED_BIT, &ct->status)) { 595 DEBUGP("nf_conntrack_in: related packet for %p\n", ct); 596 *ctinfo = IP_CT_RELATED; 597 } else { 598 DEBUGP("nf_conntrack_in: new packet for %p\n", ct); 599 *ctinfo = IP_CT_NEW; 600 } 601 *set_reply = 0; 602 } 603 skb->nfct = &ct->ct_general; 604 skb->nfctinfo = *ctinfo; 605 return ct; 606} 607 608unsigned int 609nf_conntrack_in(int pf, unsigned int hooknum, struct sk_buff **pskb) 610{ 611 struct nf_conn *ct; 612 enum ip_conntrack_info ctinfo; 613 struct nf_conntrack_l3proto *l3proto; 614 struct nf_conntrack_l4proto *l4proto; 615 unsigned int dataoff; 616 u_int8_t protonum; 617 int set_reply = 0; 618 int ret; 619 620 /* Previously seen (loopback or untracked)? Ignore. */ 621 if ((*pskb)->nfct) { 622 NF_CT_STAT_INC_ATOMIC(ignore); 623 return NF_ACCEPT; 624 } 625 626 /* rcu_read_lock()ed by nf_hook_slow */ 627 l3proto = __nf_ct_l3proto_find((u_int16_t)pf); 628 629 if ((ret = l3proto->prepare(pskb, hooknum, &dataoff, &protonum)) <= 0) { 630 DEBUGP("not prepared to track yet or error occured\n"); 631 return -ret; 632 } 633 634 l4proto = __nf_ct_l4proto_find((u_int16_t)pf, protonum); 635 636 /* It may be an special packet, error, unclean... 637 * inverse of the return code tells to the netfilter 638 * core what to do with the packet. */ 639 if (l4proto->error != NULL && 640 (ret = l4proto->error(*pskb, dataoff, &ctinfo, pf, hooknum)) <= 0) { 641 NF_CT_STAT_INC_ATOMIC(error); 642 NF_CT_STAT_INC_ATOMIC(invalid); 643 return -ret; 644 } 645 646 ct = resolve_normal_ct(*pskb, dataoff, pf, protonum, l3proto, l4proto, 647 &set_reply, &ctinfo); 648 if (!ct) { 649 /* Not valid part of a connection */ 650 NF_CT_STAT_INC_ATOMIC(invalid); 651 return NF_ACCEPT; 652 } 653 654 if (IS_ERR(ct)) { 655 /* Too stressed to deal. */ 656 NF_CT_STAT_INC_ATOMIC(drop); 657 return NF_DROP; 658 } 659 660 NF_CT_ASSERT((*pskb)->nfct); 661 662 ret = l4proto->packet(ct, *pskb, dataoff, ctinfo, pf, hooknum); 663 if (ret < 0) { 664 /* Invalid: inverse of the return code tells 665 * the netfilter core what to do */ 666 DEBUGP("nf_conntrack_in: Can't track with proto module\n"); 667 nf_conntrack_put((*pskb)->nfct); 668 (*pskb)->nfct = NULL; 669 NF_CT_STAT_INC_ATOMIC(invalid); 670 return -ret; 671 } 672 673 if (set_reply && !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status)) 674 nf_conntrack_event_cache(IPCT_STATUS, *pskb); 675 676 return ret; 677} 678EXPORT_SYMBOL_GPL(nf_conntrack_in); 679 680int nf_ct_invert_tuplepr(struct nf_conntrack_tuple *inverse, 681 const struct nf_conntrack_tuple *orig) 682{ 683 int ret; 684 685 rcu_read_lock(); 686 ret = nf_ct_invert_tuple(inverse, orig, 687 __nf_ct_l3proto_find(orig->src.l3num), 688 __nf_ct_l4proto_find(orig->src.l3num, 689 orig->dst.protonum)); 690 rcu_read_unlock(); 691 return ret; 692} 693EXPORT_SYMBOL_GPL(nf_ct_invert_tuplepr); 694 695/* Alter reply tuple (maybe alter helper). This is for NAT, and is 696 implicitly racy: see __nf_conntrack_confirm */ 697void nf_conntrack_alter_reply(struct nf_conn *ct, 698 const struct nf_conntrack_tuple *newreply) 699{ 700 struct nf_conn_help *help = nfct_help(ct); 701 struct nf_conntrack_helper *helper; 702 703 write_lock_bh(&nf_conntrack_lock); 704 /* Should be unconfirmed, so not in hash table yet */ 705 NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); 706 707 DEBUGP("Altering reply tuple of %p to ", ct); 708 NF_CT_DUMP_TUPLE(newreply); 709 710 ct->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply; 711 if (ct->master || (help && help->expecting != 0)) 712 goto out; 713 714 helper = __nf_ct_helper_find(newreply); 715 if (helper == NULL) { 716 if (help) 717 rcu_assign_pointer(help->helper, NULL); 718 goto out; 719 } 720 721 if (help == NULL) { 722 help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, GFP_ATOMIC); 723 if (help == NULL) { 724 DEBUGP("failed to add helper extension area"); 725 goto out; 726 } 727 } else { 728 memset(&help->help, 0, sizeof(help->help)); 729 } 730 731 rcu_assign_pointer(help->helper, helper); 732out: 733 write_unlock_bh(&nf_conntrack_lock); 734} 735EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply); 736 737/* Refresh conntrack for this many jiffies and do accounting if do_acct is 1 */ 738void __nf_ct_refresh_acct(struct nf_conn *ct, 739 enum ip_conntrack_info ctinfo, 740 const struct sk_buff *skb, 741 unsigned long extra_jiffies, 742 int do_acct) 743{ 744 int event = 0; 745 746 NF_CT_ASSERT(ct->timeout.data == (unsigned long)ct); 747 NF_CT_ASSERT(skb); 748 749 write_lock_bh(&nf_conntrack_lock); 750 751 /* Only update if this is not a fixed timeout */ 752 if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status)) { 753 write_unlock_bh(&nf_conntrack_lock); 754 return; 755 } 756 757 /* If not in hash table, timer will not be active yet */ 758 if (!nf_ct_is_confirmed(ct)) { 759 ct->timeout.expires = extra_jiffies; 760 event = IPCT_REFRESH; 761 } else { 762 unsigned long newtime = jiffies + extra_jiffies; 763 764 /* Only update the timeout if the new timeout is at least 765 HZ jiffies from the old timeout. Need del_timer for race 766 avoidance (may already be dying). */ 767 if (newtime - ct->timeout.expires >= HZ 768 && del_timer(&ct->timeout)) { 769 ct->timeout.expires = newtime; 770 add_timer(&ct->timeout); 771 event = IPCT_REFRESH; 772 } 773 } 774 775#ifdef CONFIG_NF_CT_ACCT 776 if (do_acct) { 777 ct->counters[CTINFO2DIR(ctinfo)].packets++; 778 ct->counters[CTINFO2DIR(ctinfo)].bytes += 779 skb->len - skb_network_offset(skb); 780 781 if ((ct->counters[CTINFO2DIR(ctinfo)].packets & 0x80000000) 782 || (ct->counters[CTINFO2DIR(ctinfo)].bytes & 0x80000000)) 783 event |= IPCT_COUNTER_FILLING; 784 } 785#endif 786 787 write_unlock_bh(&nf_conntrack_lock); 788 789 /* must be unlocked when calling event cache */ 790 if (event) 791 nf_conntrack_event_cache(event, skb); 792} 793EXPORT_SYMBOL_GPL(__nf_ct_refresh_acct); 794 795#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE) 796 797#include <linux/netfilter/nfnetlink.h> 798#include <linux/netfilter/nfnetlink_conntrack.h> 799#include <linux/mutex.h> 800 801 802/* Generic function for tcp/udp/sctp/dccp and alike. This needs to be 803 * in ip_conntrack_core, since we don't want the protocols to autoload 804 * or depend on ctnetlink */ 805int nf_ct_port_tuple_to_nfattr(struct sk_buff *skb, 806 const struct nf_conntrack_tuple *tuple) 807{ 808 NFA_PUT(skb, CTA_PROTO_SRC_PORT, sizeof(u_int16_t), 809 &tuple->src.u.tcp.port); 810 NFA_PUT(skb, CTA_PROTO_DST_PORT, sizeof(u_int16_t), 811 &tuple->dst.u.tcp.port); 812 return 0; 813 814nfattr_failure: 815 return -1; 816} 817EXPORT_SYMBOL_GPL(nf_ct_port_tuple_to_nfattr); 818 819static const size_t cta_min_proto[CTA_PROTO_MAX] = { 820 [CTA_PROTO_SRC_PORT-1] = sizeof(u_int16_t), 821 [CTA_PROTO_DST_PORT-1] = sizeof(u_int16_t) 822}; 823 824int nf_ct_port_nfattr_to_tuple(struct nfattr *tb[], 825 struct nf_conntrack_tuple *t) 826{ 827 if (!tb[CTA_PROTO_SRC_PORT-1] || !tb[CTA_PROTO_DST_PORT-1]) 828 return -EINVAL; 829 830 if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto)) 831 return -EINVAL; 832 833 t->src.u.tcp.port = *(__be16 *)NFA_DATA(tb[CTA_PROTO_SRC_PORT-1]); 834 t->dst.u.tcp.port = *(__be16 *)NFA_DATA(tb[CTA_PROTO_DST_PORT-1]); 835 836 return 0; 837} 838EXPORT_SYMBOL_GPL(nf_ct_port_nfattr_to_tuple); 839#endif 840 841/* Used by ipt_REJECT and ip6t_REJECT. */ 842void __nf_conntrack_attach(struct sk_buff *nskb, struct sk_buff *skb) 843{ 844 struct nf_conn *ct; 845 enum ip_conntrack_info ctinfo; 846 847 /* This ICMP is in reverse direction to the packet which caused it */ 848 ct = nf_ct_get(skb, &ctinfo); 849 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) 850 ctinfo = IP_CT_RELATED + IP_CT_IS_REPLY; 851 else 852 ctinfo = IP_CT_RELATED; 853 854 /* Attach to new skbuff, and increment count */ 855 nskb->nfct = &ct->ct_general; 856 nskb->nfctinfo = ctinfo; 857 nf_conntrack_get(nskb->nfct); 858} 859EXPORT_SYMBOL_GPL(__nf_conntrack_attach); 860 861static inline int 862do_iter(const struct nf_conntrack_tuple_hash *i, 863 int (*iter)(struct nf_conn *i, void *data), 864 void *data) 865{ 866 return iter(nf_ct_tuplehash_to_ctrack(i), data); 867} 868 869/* Bring out ya dead! */ 870static struct nf_conn * 871get_next_corpse(int (*iter)(struct nf_conn *i, void *data), 872 void *data, unsigned int *bucket) 873{ 874 struct nf_conntrack_tuple_hash *h; 875 struct nf_conn *ct; 876 877 write_lock_bh(&nf_conntrack_lock); 878 for (; *bucket < nf_conntrack_htable_size; (*bucket)++) { 879 list_for_each_entry(h, &nf_conntrack_hash[*bucket], list) { 880 ct = nf_ct_tuplehash_to_ctrack(h); 881 if (iter(ct, data)) 882 goto found; 883 } 884 } 885 list_for_each_entry(h, &unconfirmed, list) { 886 ct = nf_ct_tuplehash_to_ctrack(h); 887 if (iter(ct, data)) 888 set_bit(IPS_DYING_BIT, &ct->status); 889 } 890 write_unlock_bh(&nf_conntrack_lock); 891 return NULL; 892found: 893 atomic_inc(&ct->ct_general.use); 894 write_unlock_bh(&nf_conntrack_lock); 895 return ct; 896} 897 898void 899nf_ct_iterate_cleanup(int (*iter)(struct nf_conn *i, void *data), void *data) 900{ 901 struct nf_conn *ct; 902 unsigned int bucket = 0; 903 904 while ((ct = get_next_corpse(iter, data, &bucket)) != NULL) { 905 /* Time to push up daises... */ 906 if (del_timer(&ct->timeout)) 907 death_by_timeout((unsigned long)ct); 908 /* ... else the timer will get him soon. */ 909 910 nf_ct_put(ct); 911 } 912} 913EXPORT_SYMBOL_GPL(nf_ct_iterate_cleanup); 914 915static int kill_all(struct nf_conn *i, void *data) 916{ 917 return 1; 918} 919 920static void free_conntrack_hash(struct list_head *hash, int vmalloced, int size) 921{ 922 if (vmalloced) 923 vfree(hash); 924 else 925 free_pages((unsigned long)hash, 926 get_order(sizeof(struct list_head) * size)); 927} 928 929void nf_conntrack_flush(void) 930{ 931 nf_ct_iterate_cleanup(kill_all, NULL); 932} 933EXPORT_SYMBOL_GPL(nf_conntrack_flush); 934 935/* Mishearing the voices in his head, our hero wonders how he's 936 supposed to kill the mall. */ 937void nf_conntrack_cleanup(void) 938{ 939 rcu_assign_pointer(ip_ct_attach, NULL); 940 941 /* This makes sure all current packets have passed through 942 netfilter framework. Roll on, two-stage module 943 delete... */ 944 synchronize_net(); 945 946 nf_ct_event_cache_flush(); 947 i_see_dead_people: 948 nf_conntrack_flush(); 949 if (atomic_read(&nf_conntrack_count) != 0) { 950 schedule(); 951 goto i_see_dead_people; 952 } 953 /* wait until all references to nf_conntrack_untracked are dropped */ 954 while (atomic_read(&nf_conntrack_untracked.ct_general.use) > 1) 955 schedule(); 956 957 rcu_assign_pointer(nf_ct_destroy, NULL); 958 959 kmem_cache_destroy(nf_conntrack_cachep); 960 kmem_cache_destroy(nf_conntrack_expect_cachep); 961 free_conntrack_hash(nf_conntrack_hash, nf_conntrack_vmalloc, 962 nf_conntrack_htable_size); 963 964 nf_conntrack_proto_fini(); 965 nf_conntrack_helper_fini(); 966} 967 968static struct list_head *alloc_hashtable(int size, int *vmalloced) 969{ 970 struct list_head *hash; 971 unsigned int i; 972 973 *vmalloced = 0; 974 hash = (void*)__get_free_pages(GFP_KERNEL, 975 get_order(sizeof(struct list_head) 976 * size)); 977 if (!hash) { 978 *vmalloced = 1; 979 printk(KERN_WARNING "nf_conntrack: falling back to vmalloc.\n"); 980 hash = vmalloc(sizeof(struct list_head) * size); 981 } 982 983 if (hash) 984 for (i = 0; i < size; i++) 985 INIT_LIST_HEAD(&hash[i]); 986 987 return hash; 988} 989 990int set_hashsize(const char *val, struct kernel_param *kp) 991{ 992 int i, bucket, hashsize, vmalloced; 993 int old_vmalloced, old_size; 994 int rnd; 995 struct list_head *hash, *old_hash; 996 struct nf_conntrack_tuple_hash *h; 997 998 /* On boot, we can set this without any fancy locking. */ 999 if (!nf_conntrack_htable_size) 1000 return param_set_uint(val, kp); 1001 1002 hashsize = simple_strtol(val, NULL, 0); 1003 if (!hashsize) 1004 return -EINVAL; 1005 1006 hash = alloc_hashtable(hashsize, &vmalloced); 1007 if (!hash) 1008 return -ENOMEM; 1009 1010 /* We have to rehahs for the new table anyway, so we also can 1011 * use a newrandom seed */ 1012 get_random_bytes(&rnd, 4); 1013 1014 write_lock_bh(&nf_conntrack_lock); 1015 for (i = 0; i < nf_conntrack_htable_size; i++) { 1016 while (!list_empty(&nf_conntrack_hash[i])) { 1017 h = list_entry(nf_conntrack_hash[i].next, 1018 struct nf_conntrack_tuple_hash, list); 1019 list_del(&h->list); 1020 bucket = __hash_conntrack(&h->tuple, hashsize, rnd); 1021 list_add_tail(&h->list, &hash[bucket]); 1022 } 1023 } 1024 old_size = nf_conntrack_htable_size; 1025 old_vmalloced = nf_conntrack_vmalloc; 1026 old_hash = nf_conntrack_hash; 1027 1028 nf_conntrack_htable_size = hashsize; 1029 nf_conntrack_vmalloc = vmalloced; 1030 nf_conntrack_hash = hash; 1031 nf_conntrack_hash_rnd = rnd; 1032 write_unlock_bh(&nf_conntrack_lock); 1033 1034 free_conntrack_hash(old_hash, old_vmalloced, old_size); 1035 return 0; 1036} 1037 1038module_param_call(hashsize, set_hashsize, param_get_uint, 1039 &nf_conntrack_htable_size, 0600); 1040 1041int __init nf_conntrack_init(void) 1042{ 1043 int ret; 1044 1045 /* Idea from tcp.c: use 1/16384 of memory. On i386: 32MB 1046 * machine has 256 buckets. >= 1GB machines have 8192 buckets. */ 1047 if (!nf_conntrack_htable_size) { 1048 nf_conntrack_htable_size 1049 = (((num_physpages << PAGE_SHIFT) / 16384) 1050 / sizeof(struct list_head)); 1051 if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE)) 1052 nf_conntrack_htable_size = 8192; 1053 if (nf_conntrack_htable_size < 16) 1054 nf_conntrack_htable_size = 16; 1055 } 1056 nf_conntrack_max = 8 * nf_conntrack_htable_size; 1057 1058 printk("nf_conntrack version %s (%u buckets, %d max)\n", 1059 NF_CONNTRACK_VERSION, nf_conntrack_htable_size, 1060 nf_conntrack_max); 1061 1062 nf_conntrack_hash = alloc_hashtable(nf_conntrack_htable_size, 1063 &nf_conntrack_vmalloc); 1064 if (!nf_conntrack_hash) { 1065 printk(KERN_ERR "Unable to create nf_conntrack_hash\n"); 1066 goto err_out; 1067 } 1068 1069 nf_conntrack_cachep = kmem_cache_create("nf_conntrack", 1070 sizeof(struct nf_conn), 1071 0, 0, NULL, NULL); 1072 if (!nf_conntrack_cachep) { 1073 printk(KERN_ERR "Unable to create nf_conn slab cache\n"); 1074 goto err_free_hash; 1075 } 1076 1077 nf_conntrack_expect_cachep = kmem_cache_create("nf_conntrack_expect", 1078 sizeof(struct nf_conntrack_expect), 1079 0, 0, NULL, NULL); 1080 if (!nf_conntrack_expect_cachep) { 1081 printk(KERN_ERR "Unable to create nf_expect slab cache\n"); 1082 goto err_free_conntrack_slab; 1083 } 1084 1085 ret = nf_conntrack_proto_init(); 1086 if (ret < 0) 1087 goto out_free_expect_slab; 1088 1089 ret = nf_conntrack_helper_init(); 1090 if (ret < 0) 1091 goto out_fini_proto; 1092 1093 /* For use by REJECT target */ 1094 rcu_assign_pointer(ip_ct_attach, __nf_conntrack_attach); 1095 rcu_assign_pointer(nf_ct_destroy, destroy_conntrack); 1096 1097 /* Set up fake conntrack: 1098 - to never be deleted, not in any hashes */ 1099 atomic_set(&nf_conntrack_untracked.ct_general.use, 1); 1100 /* - and look it like as a confirmed connection */ 1101 set_bit(IPS_CONFIRMED_BIT, &nf_conntrack_untracked.status); 1102 1103 return ret; 1104 1105out_fini_proto: 1106 nf_conntrack_proto_fini(); 1107out_free_expect_slab: 1108 kmem_cache_destroy(nf_conntrack_expect_cachep); 1109err_free_conntrack_slab: 1110 kmem_cache_destroy(nf_conntrack_cachep); 1111err_free_hash: 1112 free_conntrack_hash(nf_conntrack_hash, nf_conntrack_vmalloc, 1113 nf_conntrack_htable_size); 1114err_out: 1115 return -ENOMEM; 1116} 1117