nf_conntrack_core.c revision e2a3123fbe58da9fd3f35cd242087896ace6049f
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 43DEFINE_RWLOCK(nf_conntrack_lock); 44EXPORT_SYMBOL_GPL(nf_conntrack_lock); 45 46/* nf_conntrack_standalone needs this */ 47atomic_t nf_conntrack_count = ATOMIC_INIT(0); 48EXPORT_SYMBOL_GPL(nf_conntrack_count); 49 50unsigned int nf_conntrack_htable_size __read_mostly; 51EXPORT_SYMBOL_GPL(nf_conntrack_htable_size); 52 53int nf_conntrack_max __read_mostly; 54EXPORT_SYMBOL_GPL(nf_conntrack_max); 55 56struct hlist_head *nf_conntrack_hash __read_mostly; 57EXPORT_SYMBOL_GPL(nf_conntrack_hash); 58 59struct nf_conn nf_conntrack_untracked __read_mostly; 60EXPORT_SYMBOL_GPL(nf_conntrack_untracked); 61 62unsigned int nf_ct_log_invalid __read_mostly; 63HLIST_HEAD(unconfirmed); 64static int nf_conntrack_vmalloc __read_mostly; 65static struct kmem_cache *nf_conntrack_cachep __read_mostly; 66static unsigned int nf_conntrack_next_id; 67 68DEFINE_PER_CPU(struct ip_conntrack_stat, nf_conntrack_stat); 69EXPORT_PER_CPU_SYMBOL(nf_conntrack_stat); 70 71static int nf_conntrack_hash_rnd_initted; 72static unsigned int nf_conntrack_hash_rnd; 73 74static u_int32_t __hash_conntrack(const struct nf_conntrack_tuple *tuple, 75 unsigned int size, unsigned int rnd) 76{ 77 unsigned int a, b; 78 79 a = jhash2(tuple->src.u3.all, ARRAY_SIZE(tuple->src.u3.all), 80 (tuple->src.l3num << 16) | tuple->dst.protonum); 81 b = jhash2(tuple->dst.u3.all, ARRAY_SIZE(tuple->dst.u3.all), 82 (tuple->src.u.all << 16) | tuple->dst.u.all); 83 84 return jhash_2words(a, b, rnd) % size; 85} 86 87static inline u_int32_t hash_conntrack(const struct nf_conntrack_tuple *tuple) 88{ 89 return __hash_conntrack(tuple, nf_conntrack_htable_size, 90 nf_conntrack_hash_rnd); 91} 92 93int 94nf_ct_get_tuple(const struct sk_buff *skb, 95 unsigned int nhoff, 96 unsigned int dataoff, 97 u_int16_t l3num, 98 u_int8_t protonum, 99 struct nf_conntrack_tuple *tuple, 100 const struct nf_conntrack_l3proto *l3proto, 101 const struct nf_conntrack_l4proto *l4proto) 102{ 103 NF_CT_TUPLE_U_BLANK(tuple); 104 105 tuple->src.l3num = l3num; 106 if (l3proto->pkt_to_tuple(skb, nhoff, tuple) == 0) 107 return 0; 108 109 tuple->dst.protonum = protonum; 110 tuple->dst.dir = IP_CT_DIR_ORIGINAL; 111 112 return l4proto->pkt_to_tuple(skb, dataoff, tuple); 113} 114EXPORT_SYMBOL_GPL(nf_ct_get_tuple); 115 116int nf_ct_get_tuplepr(const struct sk_buff *skb, 117 unsigned int nhoff, 118 u_int16_t l3num, 119 struct nf_conntrack_tuple *tuple) 120{ 121 struct nf_conntrack_l3proto *l3proto; 122 struct nf_conntrack_l4proto *l4proto; 123 unsigned int protoff; 124 u_int8_t protonum; 125 int ret; 126 127 rcu_read_lock(); 128 129 l3proto = __nf_ct_l3proto_find(l3num); 130 ret = l3proto->get_l4proto(skb, nhoff, &protoff, &protonum); 131 if (ret != NF_ACCEPT) { 132 rcu_read_unlock(); 133 return 0; 134 } 135 136 l4proto = __nf_ct_l4proto_find(l3num, protonum); 137 138 ret = nf_ct_get_tuple(skb, nhoff, protoff, l3num, protonum, tuple, 139 l3proto, l4proto); 140 141 rcu_read_unlock(); 142 return ret; 143} 144EXPORT_SYMBOL_GPL(nf_ct_get_tuplepr); 145 146int 147nf_ct_invert_tuple(struct nf_conntrack_tuple *inverse, 148 const struct nf_conntrack_tuple *orig, 149 const struct nf_conntrack_l3proto *l3proto, 150 const struct nf_conntrack_l4proto *l4proto) 151{ 152 NF_CT_TUPLE_U_BLANK(inverse); 153 154 inverse->src.l3num = orig->src.l3num; 155 if (l3proto->invert_tuple(inverse, orig) == 0) 156 return 0; 157 158 inverse->dst.dir = !orig->dst.dir; 159 160 inverse->dst.protonum = orig->dst.protonum; 161 return l4proto->invert_tuple(inverse, orig); 162} 163EXPORT_SYMBOL_GPL(nf_ct_invert_tuple); 164 165static void 166clean_from_lists(struct nf_conn *ct) 167{ 168 pr_debug("clean_from_lists(%p)\n", ct); 169 hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode); 170 hlist_del(&ct->tuplehash[IP_CT_DIR_REPLY].hnode); 171 172 /* Destroy all pending expectations */ 173 nf_ct_remove_expectations(ct); 174} 175 176static void 177destroy_conntrack(struct nf_conntrack *nfct) 178{ 179 struct nf_conn *ct = (struct nf_conn *)nfct; 180 struct nf_conntrack_l4proto *l4proto; 181 182 pr_debug("destroy_conntrack(%p)\n", ct); 183 NF_CT_ASSERT(atomic_read(&nfct->use) == 0); 184 NF_CT_ASSERT(!timer_pending(&ct->timeout)); 185 186 nf_conntrack_event(IPCT_DESTROY, ct); 187 set_bit(IPS_DYING_BIT, &ct->status); 188 189 /* To make sure we don't get any weird locking issues here: 190 * destroy_conntrack() MUST NOT be called with a write lock 191 * to nf_conntrack_lock!!! -HW */ 192 rcu_read_lock(); 193 l4proto = __nf_ct_l4proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.l3num, 194 ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum); 195 if (l4proto && l4proto->destroy) 196 l4proto->destroy(ct); 197 198 nf_ct_ext_destroy(ct); 199 200 rcu_read_unlock(); 201 202 write_lock_bh(&nf_conntrack_lock); 203 /* Expectations will have been removed in clean_from_lists, 204 * except TFTP can create an expectation on the first packet, 205 * before connection is in the list, so we need to clean here, 206 * too. */ 207 nf_ct_remove_expectations(ct); 208 209 /* We overload first tuple to link into unconfirmed list. */ 210 if (!nf_ct_is_confirmed(ct)) { 211 BUG_ON(hlist_unhashed(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode)); 212 hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode); 213 } 214 215 NF_CT_STAT_INC(delete); 216 write_unlock_bh(&nf_conntrack_lock); 217 218 if (ct->master) 219 nf_ct_put(ct->master); 220 221 pr_debug("destroy_conntrack: returning ct=%p to slab\n", ct); 222 nf_conntrack_free(ct); 223} 224 225static void death_by_timeout(unsigned long ul_conntrack) 226{ 227 struct nf_conn *ct = (void *)ul_conntrack; 228 struct nf_conn_help *help = nfct_help(ct); 229 struct nf_conntrack_helper *helper; 230 231 if (help) { 232 rcu_read_lock(); 233 helper = rcu_dereference(help->helper); 234 if (helper && helper->destroy) 235 helper->destroy(ct); 236 rcu_read_unlock(); 237 } 238 239 write_lock_bh(&nf_conntrack_lock); 240 /* Inside lock so preempt is disabled on module removal path. 241 * Otherwise we can get spurious warnings. */ 242 NF_CT_STAT_INC(delete_list); 243 clean_from_lists(ct); 244 write_unlock_bh(&nf_conntrack_lock); 245 nf_ct_put(ct); 246} 247 248struct nf_conntrack_tuple_hash * 249__nf_conntrack_find(const struct nf_conntrack_tuple *tuple, 250 const struct nf_conn *ignored_conntrack) 251{ 252 struct nf_conntrack_tuple_hash *h; 253 struct hlist_node *n; 254 unsigned int hash = hash_conntrack(tuple); 255 256 hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode) { 257 if (nf_ct_tuplehash_to_ctrack(h) != ignored_conntrack && 258 nf_ct_tuple_equal(tuple, &h->tuple)) { 259 NF_CT_STAT_INC(found); 260 return h; 261 } 262 NF_CT_STAT_INC(searched); 263 } 264 265 return NULL; 266} 267EXPORT_SYMBOL_GPL(__nf_conntrack_find); 268 269/* Find a connection corresponding to a tuple. */ 270struct nf_conntrack_tuple_hash * 271nf_conntrack_find_get(const struct nf_conntrack_tuple *tuple) 272{ 273 struct nf_conntrack_tuple_hash *h; 274 275 read_lock_bh(&nf_conntrack_lock); 276 h = __nf_conntrack_find(tuple, NULL); 277 if (h) 278 atomic_inc(&nf_ct_tuplehash_to_ctrack(h)->ct_general.use); 279 read_unlock_bh(&nf_conntrack_lock); 280 281 return h; 282} 283EXPORT_SYMBOL_GPL(nf_conntrack_find_get); 284 285static void __nf_conntrack_hash_insert(struct nf_conn *ct, 286 unsigned int hash, 287 unsigned int repl_hash) 288{ 289 ct->id = ++nf_conntrack_next_id; 290 hlist_add_head(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode, 291 &nf_conntrack_hash[hash]); 292 hlist_add_head(&ct->tuplehash[IP_CT_DIR_REPLY].hnode, 293 &nf_conntrack_hash[repl_hash]); 294} 295 296void nf_conntrack_hash_insert(struct nf_conn *ct) 297{ 298 unsigned int hash, repl_hash; 299 300 hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); 301 repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); 302 303 write_lock_bh(&nf_conntrack_lock); 304 __nf_conntrack_hash_insert(ct, hash, repl_hash); 305 write_unlock_bh(&nf_conntrack_lock); 306} 307EXPORT_SYMBOL_GPL(nf_conntrack_hash_insert); 308 309/* Confirm a connection given skb; places it in hash table */ 310int 311__nf_conntrack_confirm(struct sk_buff **pskb) 312{ 313 unsigned int hash, repl_hash; 314 struct nf_conntrack_tuple_hash *h; 315 struct nf_conn *ct; 316 struct nf_conn_help *help; 317 struct hlist_node *n; 318 enum ip_conntrack_info ctinfo; 319 320 ct = nf_ct_get(*pskb, &ctinfo); 321 322 /* ipt_REJECT uses nf_conntrack_attach to attach related 323 ICMP/TCP RST packets in other direction. Actual packet 324 which created connection will be IP_CT_NEW or for an 325 expected connection, IP_CT_RELATED. */ 326 if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) 327 return NF_ACCEPT; 328 329 hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); 330 repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); 331 332 /* We're not in hash table, and we refuse to set up related 333 connections for unconfirmed conns. But packet copies and 334 REJECT will give spurious warnings here. */ 335 /* NF_CT_ASSERT(atomic_read(&ct->ct_general.use) == 1); */ 336 337 /* No external references means noone else could have 338 confirmed us. */ 339 NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); 340 pr_debug("Confirming conntrack %p\n", ct); 341 342 write_lock_bh(&nf_conntrack_lock); 343 344 /* See if there's one in the list already, including reverse: 345 NAT could have grabbed it without realizing, since we're 346 not in the hash. If there is, we lost race. */ 347 hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode) 348 if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, 349 &h->tuple)) 350 goto out; 351 hlist_for_each_entry(h, n, &nf_conntrack_hash[repl_hash], hnode) 352 if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_REPLY].tuple, 353 &h->tuple)) 354 goto out; 355 356 /* Remove from unconfirmed list */ 357 hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode); 358 359 __nf_conntrack_hash_insert(ct, hash, repl_hash); 360 /* Timer relative to confirmation time, not original 361 setting time, otherwise we'd get timer wrap in 362 weird delay cases. */ 363 ct->timeout.expires += jiffies; 364 add_timer(&ct->timeout); 365 atomic_inc(&ct->ct_general.use); 366 set_bit(IPS_CONFIRMED_BIT, &ct->status); 367 NF_CT_STAT_INC(insert); 368 write_unlock_bh(&nf_conntrack_lock); 369 help = nfct_help(ct); 370 if (help && help->helper) 371 nf_conntrack_event_cache(IPCT_HELPER, *pskb); 372#ifdef CONFIG_NF_NAT_NEEDED 373 if (test_bit(IPS_SRC_NAT_DONE_BIT, &ct->status) || 374 test_bit(IPS_DST_NAT_DONE_BIT, &ct->status)) 375 nf_conntrack_event_cache(IPCT_NATINFO, *pskb); 376#endif 377 nf_conntrack_event_cache(master_ct(ct) ? 378 IPCT_RELATED : IPCT_NEW, *pskb); 379 return NF_ACCEPT; 380 381out: 382 NF_CT_STAT_INC(insert_failed); 383 write_unlock_bh(&nf_conntrack_lock); 384 return NF_DROP; 385} 386EXPORT_SYMBOL_GPL(__nf_conntrack_confirm); 387 388/* Returns true if a connection correspondings to the tuple (required 389 for NAT). */ 390int 391nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple, 392 const struct nf_conn *ignored_conntrack) 393{ 394 struct nf_conntrack_tuple_hash *h; 395 396 read_lock_bh(&nf_conntrack_lock); 397 h = __nf_conntrack_find(tuple, ignored_conntrack); 398 read_unlock_bh(&nf_conntrack_lock); 399 400 return h != NULL; 401} 402EXPORT_SYMBOL_GPL(nf_conntrack_tuple_taken); 403 404#define NF_CT_EVICTION_RANGE 8 405 406/* There's a small race here where we may free a just-assured 407 connection. Too bad: we're in trouble anyway. */ 408static int early_drop(unsigned int hash) 409{ 410 /* Use oldest entry, which is roughly LRU */ 411 struct nf_conntrack_tuple_hash *h; 412 struct nf_conn *ct = NULL, *tmp; 413 struct hlist_node *n; 414 unsigned int i, cnt = 0; 415 int dropped = 0; 416 417 read_lock_bh(&nf_conntrack_lock); 418 for (i = 0; i < nf_conntrack_htable_size; i++) { 419 hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode) { 420 tmp = nf_ct_tuplehash_to_ctrack(h); 421 if (!test_bit(IPS_ASSURED_BIT, &tmp->status)) 422 ct = tmp; 423 cnt++; 424 } 425 if (ct || cnt >= NF_CT_EVICTION_RANGE) 426 break; 427 hash = (hash + 1) % nf_conntrack_htable_size; 428 } 429 if (ct) 430 atomic_inc(&ct->ct_general.use); 431 read_unlock_bh(&nf_conntrack_lock); 432 433 if (!ct) 434 return dropped; 435 436 if (del_timer(&ct->timeout)) { 437 death_by_timeout((unsigned long)ct); 438 dropped = 1; 439 NF_CT_STAT_INC_ATOMIC(early_drop); 440 } 441 nf_ct_put(ct); 442 return dropped; 443} 444 445struct nf_conn *nf_conntrack_alloc(const struct nf_conntrack_tuple *orig, 446 const struct nf_conntrack_tuple *repl) 447{ 448 struct nf_conn *conntrack = NULL; 449 450 if (unlikely(!nf_conntrack_hash_rnd_initted)) { 451 get_random_bytes(&nf_conntrack_hash_rnd, 4); 452 nf_conntrack_hash_rnd_initted = 1; 453 } 454 455 /* We don't want any race condition at early drop stage */ 456 atomic_inc(&nf_conntrack_count); 457 458 if (nf_conntrack_max 459 && atomic_read(&nf_conntrack_count) > nf_conntrack_max) { 460 unsigned int hash = hash_conntrack(orig); 461 if (!early_drop(hash)) { 462 atomic_dec(&nf_conntrack_count); 463 if (net_ratelimit()) 464 printk(KERN_WARNING 465 "nf_conntrack: table full, dropping" 466 " packet.\n"); 467 return ERR_PTR(-ENOMEM); 468 } 469 } 470 471 conntrack = kmem_cache_zalloc(nf_conntrack_cachep, GFP_ATOMIC); 472 if (conntrack == NULL) { 473 pr_debug("nf_conntrack_alloc: Can't alloc conntrack.\n"); 474 atomic_dec(&nf_conntrack_count); 475 return ERR_PTR(-ENOMEM); 476 } 477 478 atomic_set(&conntrack->ct_general.use, 1); 479 conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *orig; 480 conntrack->tuplehash[IP_CT_DIR_REPLY].tuple = *repl; 481 /* Don't set timer yet: wait for confirmation */ 482 setup_timer(&conntrack->timeout, death_by_timeout, 483 (unsigned long)conntrack); 484 485 return conntrack; 486} 487EXPORT_SYMBOL_GPL(nf_conntrack_alloc); 488 489void nf_conntrack_free(struct nf_conn *conntrack) 490{ 491 nf_ct_ext_free(conntrack); 492 kmem_cache_free(nf_conntrack_cachep, conntrack); 493 atomic_dec(&nf_conntrack_count); 494} 495EXPORT_SYMBOL_GPL(nf_conntrack_free); 496 497/* Allocate a new conntrack: we return -ENOMEM if classification 498 failed due to stress. Otherwise it really is unclassifiable. */ 499static struct nf_conntrack_tuple_hash * 500init_conntrack(const struct nf_conntrack_tuple *tuple, 501 struct nf_conntrack_l3proto *l3proto, 502 struct nf_conntrack_l4proto *l4proto, 503 struct sk_buff *skb, 504 unsigned int dataoff) 505{ 506 struct nf_conn *conntrack; 507 struct nf_conn_help *help; 508 struct nf_conntrack_tuple repl_tuple; 509 struct nf_conntrack_expect *exp; 510 511 if (!nf_ct_invert_tuple(&repl_tuple, tuple, l3proto, l4proto)) { 512 pr_debug("Can't invert tuple.\n"); 513 return NULL; 514 } 515 516 conntrack = nf_conntrack_alloc(tuple, &repl_tuple); 517 if (conntrack == NULL || IS_ERR(conntrack)) { 518 pr_debug("Can't allocate conntrack.\n"); 519 return (struct nf_conntrack_tuple_hash *)conntrack; 520 } 521 522 if (!l4proto->new(conntrack, skb, dataoff)) { 523 nf_conntrack_free(conntrack); 524 pr_debug("init conntrack: can't track with proto module\n"); 525 return NULL; 526 } 527 528 write_lock_bh(&nf_conntrack_lock); 529 exp = nf_ct_find_expectation(tuple); 530 if (exp) { 531 pr_debug("conntrack: expectation arrives ct=%p exp=%p\n", 532 conntrack, exp); 533 /* Welcome, Mr. Bond. We've been expecting you... */ 534 __set_bit(IPS_EXPECTED_BIT, &conntrack->status); 535 conntrack->master = exp->master; 536 if (exp->helper) { 537 help = nf_ct_helper_ext_add(conntrack, GFP_ATOMIC); 538 if (help) 539 rcu_assign_pointer(help->helper, exp->helper); 540 } 541 542#ifdef CONFIG_NF_CONNTRACK_MARK 543 conntrack->mark = exp->master->mark; 544#endif 545#ifdef CONFIG_NF_CONNTRACK_SECMARK 546 conntrack->secmark = exp->master->secmark; 547#endif 548 nf_conntrack_get(&conntrack->master->ct_general); 549 NF_CT_STAT_INC(expect_new); 550 } else { 551 struct nf_conntrack_helper *helper; 552 553 helper = __nf_ct_helper_find(&repl_tuple); 554 if (helper) { 555 help = nf_ct_helper_ext_add(conntrack, GFP_ATOMIC); 556 if (help) 557 rcu_assign_pointer(help->helper, helper); 558 } 559 NF_CT_STAT_INC(new); 560 } 561 562 /* Overload tuple linked list to put us in unconfirmed list. */ 563 hlist_add_head(&conntrack->tuplehash[IP_CT_DIR_ORIGINAL].hnode, 564 &unconfirmed); 565 566 write_unlock_bh(&nf_conntrack_lock); 567 568 if (exp) { 569 if (exp->expectfn) 570 exp->expectfn(conntrack, exp); 571 nf_ct_expect_put(exp); 572 } 573 574 return &conntrack->tuplehash[IP_CT_DIR_ORIGINAL]; 575} 576 577/* On success, returns conntrack ptr, sets skb->nfct and ctinfo */ 578static inline struct nf_conn * 579resolve_normal_ct(struct sk_buff *skb, 580 unsigned int dataoff, 581 u_int16_t l3num, 582 u_int8_t protonum, 583 struct nf_conntrack_l3proto *l3proto, 584 struct nf_conntrack_l4proto *l4proto, 585 int *set_reply, 586 enum ip_conntrack_info *ctinfo) 587{ 588 struct nf_conntrack_tuple tuple; 589 struct nf_conntrack_tuple_hash *h; 590 struct nf_conn *ct; 591 592 if (!nf_ct_get_tuple(skb, skb_network_offset(skb), 593 dataoff, l3num, protonum, &tuple, l3proto, 594 l4proto)) { 595 pr_debug("resolve_normal_ct: Can't get tuple\n"); 596 return NULL; 597 } 598 599 /* look for tuple match */ 600 h = nf_conntrack_find_get(&tuple); 601 if (!h) { 602 h = init_conntrack(&tuple, l3proto, l4proto, skb, dataoff); 603 if (!h) 604 return NULL; 605 if (IS_ERR(h)) 606 return (void *)h; 607 } 608 ct = nf_ct_tuplehash_to_ctrack(h); 609 610 /* It exists; we have (non-exclusive) reference. */ 611 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) { 612 *ctinfo = IP_CT_ESTABLISHED + IP_CT_IS_REPLY; 613 /* Please set reply bit if this packet OK */ 614 *set_reply = 1; 615 } else { 616 /* Once we've had two way comms, always ESTABLISHED. */ 617 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { 618 pr_debug("nf_conntrack_in: normal packet for %p\n", ct); 619 *ctinfo = IP_CT_ESTABLISHED; 620 } else if (test_bit(IPS_EXPECTED_BIT, &ct->status)) { 621 pr_debug("nf_conntrack_in: related packet for %p\n", 622 ct); 623 *ctinfo = IP_CT_RELATED; 624 } else { 625 pr_debug("nf_conntrack_in: new packet for %p\n", ct); 626 *ctinfo = IP_CT_NEW; 627 } 628 *set_reply = 0; 629 } 630 skb->nfct = &ct->ct_general; 631 skb->nfctinfo = *ctinfo; 632 return ct; 633} 634 635unsigned int 636nf_conntrack_in(int pf, unsigned int hooknum, struct sk_buff **pskb) 637{ 638 struct nf_conn *ct; 639 enum ip_conntrack_info ctinfo; 640 struct nf_conntrack_l3proto *l3proto; 641 struct nf_conntrack_l4proto *l4proto; 642 unsigned int dataoff; 643 u_int8_t protonum; 644 int set_reply = 0; 645 int ret; 646 647 /* Previously seen (loopback or untracked)? Ignore. */ 648 if ((*pskb)->nfct) { 649 NF_CT_STAT_INC_ATOMIC(ignore); 650 return NF_ACCEPT; 651 } 652 653 /* rcu_read_lock()ed by nf_hook_slow */ 654 l3proto = __nf_ct_l3proto_find((u_int16_t)pf); 655 ret = l3proto->get_l4proto(*pskb, skb_network_offset(*pskb), 656 &dataoff, &protonum); 657 if (ret <= 0) { 658 pr_debug("not prepared to track yet or error occured\n"); 659 NF_CT_STAT_INC_ATOMIC(error); 660 NF_CT_STAT_INC_ATOMIC(invalid); 661 return -ret; 662 } 663 664 l4proto = __nf_ct_l4proto_find((u_int16_t)pf, protonum); 665 666 /* It may be an special packet, error, unclean... 667 * inverse of the return code tells to the netfilter 668 * core what to do with the packet. */ 669 if (l4proto->error != NULL && 670 (ret = l4proto->error(*pskb, dataoff, &ctinfo, pf, hooknum)) <= 0) { 671 NF_CT_STAT_INC_ATOMIC(error); 672 NF_CT_STAT_INC_ATOMIC(invalid); 673 return -ret; 674 } 675 676 ct = resolve_normal_ct(*pskb, dataoff, pf, protonum, l3proto, l4proto, 677 &set_reply, &ctinfo); 678 if (!ct) { 679 /* Not valid part of a connection */ 680 NF_CT_STAT_INC_ATOMIC(invalid); 681 return NF_ACCEPT; 682 } 683 684 if (IS_ERR(ct)) { 685 /* Too stressed to deal. */ 686 NF_CT_STAT_INC_ATOMIC(drop); 687 return NF_DROP; 688 } 689 690 NF_CT_ASSERT((*pskb)->nfct); 691 692 ret = l4proto->packet(ct, *pskb, dataoff, ctinfo, pf, hooknum); 693 if (ret < 0) { 694 /* Invalid: inverse of the return code tells 695 * the netfilter core what to do */ 696 pr_debug("nf_conntrack_in: Can't track with proto module\n"); 697 nf_conntrack_put((*pskb)->nfct); 698 (*pskb)->nfct = NULL; 699 NF_CT_STAT_INC_ATOMIC(invalid); 700 return -ret; 701 } 702 703 if (set_reply && !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status)) 704 nf_conntrack_event_cache(IPCT_STATUS, *pskb); 705 706 return ret; 707} 708EXPORT_SYMBOL_GPL(nf_conntrack_in); 709 710int nf_ct_invert_tuplepr(struct nf_conntrack_tuple *inverse, 711 const struct nf_conntrack_tuple *orig) 712{ 713 int ret; 714 715 rcu_read_lock(); 716 ret = nf_ct_invert_tuple(inverse, orig, 717 __nf_ct_l3proto_find(orig->src.l3num), 718 __nf_ct_l4proto_find(orig->src.l3num, 719 orig->dst.protonum)); 720 rcu_read_unlock(); 721 return ret; 722} 723EXPORT_SYMBOL_GPL(nf_ct_invert_tuplepr); 724 725/* Alter reply tuple (maybe alter helper). This is for NAT, and is 726 implicitly racy: see __nf_conntrack_confirm */ 727void nf_conntrack_alter_reply(struct nf_conn *ct, 728 const struct nf_conntrack_tuple *newreply) 729{ 730 struct nf_conn_help *help = nfct_help(ct); 731 struct nf_conntrack_helper *helper; 732 733 write_lock_bh(&nf_conntrack_lock); 734 /* Should be unconfirmed, so not in hash table yet */ 735 NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); 736 737 pr_debug("Altering reply tuple of %p to ", ct); 738 NF_CT_DUMP_TUPLE(newreply); 739 740 ct->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply; 741 if (ct->master || (help && help->expecting != 0)) 742 goto out; 743 744 helper = __nf_ct_helper_find(newreply); 745 if (helper == NULL) { 746 if (help) 747 rcu_assign_pointer(help->helper, NULL); 748 goto out; 749 } 750 751 if (help == NULL) { 752 help = nf_ct_helper_ext_add(ct, GFP_ATOMIC); 753 if (help == NULL) 754 goto out; 755 } else { 756 memset(&help->help, 0, sizeof(help->help)); 757 } 758 759 rcu_assign_pointer(help->helper, helper); 760out: 761 write_unlock_bh(&nf_conntrack_lock); 762} 763EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply); 764 765/* Refresh conntrack for this many jiffies and do accounting if do_acct is 1 */ 766void __nf_ct_refresh_acct(struct nf_conn *ct, 767 enum ip_conntrack_info ctinfo, 768 const struct sk_buff *skb, 769 unsigned long extra_jiffies, 770 int do_acct) 771{ 772 int event = 0; 773 774 NF_CT_ASSERT(ct->timeout.data == (unsigned long)ct); 775 NF_CT_ASSERT(skb); 776 777 write_lock_bh(&nf_conntrack_lock); 778 779 /* Only update if this is not a fixed timeout */ 780 if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status)) { 781 write_unlock_bh(&nf_conntrack_lock); 782 return; 783 } 784 785 /* If not in hash table, timer will not be active yet */ 786 if (!nf_ct_is_confirmed(ct)) { 787 ct->timeout.expires = extra_jiffies; 788 event = IPCT_REFRESH; 789 } else { 790 unsigned long newtime = jiffies + extra_jiffies; 791 792 /* Only update the timeout if the new timeout is at least 793 HZ jiffies from the old timeout. Need del_timer for race 794 avoidance (may already be dying). */ 795 if (newtime - ct->timeout.expires >= HZ 796 && del_timer(&ct->timeout)) { 797 ct->timeout.expires = newtime; 798 add_timer(&ct->timeout); 799 event = IPCT_REFRESH; 800 } 801 } 802 803#ifdef CONFIG_NF_CT_ACCT 804 if (do_acct) { 805 ct->counters[CTINFO2DIR(ctinfo)].packets++; 806 ct->counters[CTINFO2DIR(ctinfo)].bytes += 807 skb->len - skb_network_offset(skb); 808 809 if ((ct->counters[CTINFO2DIR(ctinfo)].packets & 0x80000000) 810 || (ct->counters[CTINFO2DIR(ctinfo)].bytes & 0x80000000)) 811 event |= IPCT_COUNTER_FILLING; 812 } 813#endif 814 815 write_unlock_bh(&nf_conntrack_lock); 816 817 /* must be unlocked when calling event cache */ 818 if (event) 819 nf_conntrack_event_cache(event, skb); 820} 821EXPORT_SYMBOL_GPL(__nf_ct_refresh_acct); 822 823#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE) 824 825#include <linux/netfilter/nfnetlink.h> 826#include <linux/netfilter/nfnetlink_conntrack.h> 827#include <linux/mutex.h> 828 829 830/* Generic function for tcp/udp/sctp/dccp and alike. This needs to be 831 * in ip_conntrack_core, since we don't want the protocols to autoload 832 * or depend on ctnetlink */ 833int nf_ct_port_tuple_to_nfattr(struct sk_buff *skb, 834 const struct nf_conntrack_tuple *tuple) 835{ 836 NFA_PUT(skb, CTA_PROTO_SRC_PORT, sizeof(u_int16_t), 837 &tuple->src.u.tcp.port); 838 NFA_PUT(skb, CTA_PROTO_DST_PORT, sizeof(u_int16_t), 839 &tuple->dst.u.tcp.port); 840 return 0; 841 842nfattr_failure: 843 return -1; 844} 845EXPORT_SYMBOL_GPL(nf_ct_port_tuple_to_nfattr); 846 847static const size_t cta_min_proto[CTA_PROTO_MAX] = { 848 [CTA_PROTO_SRC_PORT-1] = sizeof(u_int16_t), 849 [CTA_PROTO_DST_PORT-1] = sizeof(u_int16_t) 850}; 851 852int nf_ct_port_nfattr_to_tuple(struct nfattr *tb[], 853 struct nf_conntrack_tuple *t) 854{ 855 if (!tb[CTA_PROTO_SRC_PORT-1] || !tb[CTA_PROTO_DST_PORT-1]) 856 return -EINVAL; 857 858 if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto)) 859 return -EINVAL; 860 861 t->src.u.tcp.port = *(__be16 *)NFA_DATA(tb[CTA_PROTO_SRC_PORT-1]); 862 t->dst.u.tcp.port = *(__be16 *)NFA_DATA(tb[CTA_PROTO_DST_PORT-1]); 863 864 return 0; 865} 866EXPORT_SYMBOL_GPL(nf_ct_port_nfattr_to_tuple); 867#endif 868 869/* Used by ipt_REJECT and ip6t_REJECT. */ 870void __nf_conntrack_attach(struct sk_buff *nskb, struct sk_buff *skb) 871{ 872 struct nf_conn *ct; 873 enum ip_conntrack_info ctinfo; 874 875 /* This ICMP is in reverse direction to the packet which caused it */ 876 ct = nf_ct_get(skb, &ctinfo); 877 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) 878 ctinfo = IP_CT_RELATED + IP_CT_IS_REPLY; 879 else 880 ctinfo = IP_CT_RELATED; 881 882 /* Attach to new skbuff, and increment count */ 883 nskb->nfct = &ct->ct_general; 884 nskb->nfctinfo = ctinfo; 885 nf_conntrack_get(nskb->nfct); 886} 887EXPORT_SYMBOL_GPL(__nf_conntrack_attach); 888 889static inline int 890do_iter(const struct nf_conntrack_tuple_hash *i, 891 int (*iter)(struct nf_conn *i, void *data), 892 void *data) 893{ 894 return iter(nf_ct_tuplehash_to_ctrack(i), data); 895} 896 897/* Bring out ya dead! */ 898static struct nf_conn * 899get_next_corpse(int (*iter)(struct nf_conn *i, void *data), 900 void *data, unsigned int *bucket) 901{ 902 struct nf_conntrack_tuple_hash *h; 903 struct nf_conn *ct; 904 struct hlist_node *n; 905 906 write_lock_bh(&nf_conntrack_lock); 907 for (; *bucket < nf_conntrack_htable_size; (*bucket)++) { 908 hlist_for_each_entry(h, n, &nf_conntrack_hash[*bucket], hnode) { 909 ct = nf_ct_tuplehash_to_ctrack(h); 910 if (iter(ct, data)) 911 goto found; 912 } 913 } 914 hlist_for_each_entry(h, n, &unconfirmed, hnode) { 915 ct = nf_ct_tuplehash_to_ctrack(h); 916 if (iter(ct, data)) 917 set_bit(IPS_DYING_BIT, &ct->status); 918 } 919 write_unlock_bh(&nf_conntrack_lock); 920 return NULL; 921found: 922 atomic_inc(&ct->ct_general.use); 923 write_unlock_bh(&nf_conntrack_lock); 924 return ct; 925} 926 927void 928nf_ct_iterate_cleanup(int (*iter)(struct nf_conn *i, void *data), void *data) 929{ 930 struct nf_conn *ct; 931 unsigned int bucket = 0; 932 933 while ((ct = get_next_corpse(iter, data, &bucket)) != NULL) { 934 /* Time to push up daises... */ 935 if (del_timer(&ct->timeout)) 936 death_by_timeout((unsigned long)ct); 937 /* ... else the timer will get him soon. */ 938 939 nf_ct_put(ct); 940 } 941} 942EXPORT_SYMBOL_GPL(nf_ct_iterate_cleanup); 943 944static int kill_all(struct nf_conn *i, void *data) 945{ 946 return 1; 947} 948 949void nf_ct_free_hashtable(struct hlist_head *hash, int vmalloced, int size) 950{ 951 if (vmalloced) 952 vfree(hash); 953 else 954 free_pages((unsigned long)hash, 955 get_order(sizeof(struct hlist_head) * size)); 956} 957EXPORT_SYMBOL_GPL(nf_ct_free_hashtable); 958 959void nf_conntrack_flush(void) 960{ 961 nf_ct_iterate_cleanup(kill_all, NULL); 962} 963EXPORT_SYMBOL_GPL(nf_conntrack_flush); 964 965/* Mishearing the voices in his head, our hero wonders how he's 966 supposed to kill the mall. */ 967void nf_conntrack_cleanup(void) 968{ 969 rcu_assign_pointer(ip_ct_attach, NULL); 970 971 /* This makes sure all current packets have passed through 972 netfilter framework. Roll on, two-stage module 973 delete... */ 974 synchronize_net(); 975 976 nf_ct_event_cache_flush(); 977 i_see_dead_people: 978 nf_conntrack_flush(); 979 if (atomic_read(&nf_conntrack_count) != 0) { 980 schedule(); 981 goto i_see_dead_people; 982 } 983 /* wait until all references to nf_conntrack_untracked are dropped */ 984 while (atomic_read(&nf_conntrack_untracked.ct_general.use) > 1) 985 schedule(); 986 987 rcu_assign_pointer(nf_ct_destroy, NULL); 988 989 kmem_cache_destroy(nf_conntrack_cachep); 990 nf_ct_free_hashtable(nf_conntrack_hash, nf_conntrack_vmalloc, 991 nf_conntrack_htable_size); 992 993 nf_conntrack_proto_fini(); 994 nf_conntrack_helper_fini(); 995 nf_conntrack_expect_fini(); 996} 997 998struct hlist_head *nf_ct_alloc_hashtable(int *sizep, int *vmalloced) 999{ 1000 struct hlist_head *hash; 1001 unsigned int size, i; 1002 1003 *vmalloced = 0; 1004 1005 size = *sizep = roundup(*sizep, PAGE_SIZE / sizeof(struct hlist_head)); 1006 hash = (void*)__get_free_pages(GFP_KERNEL, 1007 get_order(sizeof(struct hlist_head) 1008 * size)); 1009 if (!hash) { 1010 *vmalloced = 1; 1011 printk(KERN_WARNING "nf_conntrack: falling back to vmalloc.\n"); 1012 hash = vmalloc(sizeof(struct hlist_head) * size); 1013 } 1014 1015 if (hash) 1016 for (i = 0; i < size; i++) 1017 INIT_HLIST_HEAD(&hash[i]); 1018 1019 return hash; 1020} 1021EXPORT_SYMBOL_GPL(nf_ct_alloc_hashtable); 1022 1023int set_hashsize(const char *val, struct kernel_param *kp) 1024{ 1025 int i, bucket, hashsize, vmalloced; 1026 int old_vmalloced, old_size; 1027 int rnd; 1028 struct hlist_head *hash, *old_hash; 1029 struct nf_conntrack_tuple_hash *h; 1030 1031 /* On boot, we can set this without any fancy locking. */ 1032 if (!nf_conntrack_htable_size) 1033 return param_set_uint(val, kp); 1034 1035 hashsize = simple_strtol(val, NULL, 0); 1036 if (!hashsize) 1037 return -EINVAL; 1038 1039 hash = nf_ct_alloc_hashtable(&hashsize, &vmalloced); 1040 if (!hash) 1041 return -ENOMEM; 1042 1043 /* We have to rehahs for the new table anyway, so we also can 1044 * use a newrandom seed */ 1045 get_random_bytes(&rnd, 4); 1046 1047 write_lock_bh(&nf_conntrack_lock); 1048 for (i = 0; i < nf_conntrack_htable_size; i++) { 1049 while (!hlist_empty(&nf_conntrack_hash[i])) { 1050 h = hlist_entry(nf_conntrack_hash[i].first, 1051 struct nf_conntrack_tuple_hash, hnode); 1052 hlist_del(&h->hnode); 1053 bucket = __hash_conntrack(&h->tuple, hashsize, rnd); 1054 hlist_add_head(&h->hnode, &hash[bucket]); 1055 } 1056 } 1057 old_size = nf_conntrack_htable_size; 1058 old_vmalloced = nf_conntrack_vmalloc; 1059 old_hash = nf_conntrack_hash; 1060 1061 nf_conntrack_htable_size = hashsize; 1062 nf_conntrack_vmalloc = vmalloced; 1063 nf_conntrack_hash = hash; 1064 nf_conntrack_hash_rnd = rnd; 1065 write_unlock_bh(&nf_conntrack_lock); 1066 1067 nf_ct_free_hashtable(old_hash, old_vmalloced, old_size); 1068 return 0; 1069} 1070 1071module_param_call(hashsize, set_hashsize, param_get_uint, 1072 &nf_conntrack_htable_size, 0600); 1073 1074int __init nf_conntrack_init(void) 1075{ 1076 int max_factor = 8; 1077 int ret; 1078 1079 /* Idea from tcp.c: use 1/16384 of memory. On i386: 32MB 1080 * machine has 512 buckets. >= 1GB machines have 16384 buckets. */ 1081 if (!nf_conntrack_htable_size) { 1082 nf_conntrack_htable_size 1083 = (((num_physpages << PAGE_SHIFT) / 16384) 1084 / sizeof(struct hlist_head)); 1085 if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE)) 1086 nf_conntrack_htable_size = 16384; 1087 if (nf_conntrack_htable_size < 32) 1088 nf_conntrack_htable_size = 32; 1089 1090 /* Use a max. factor of four by default to get the same max as 1091 * with the old struct list_heads. When a table size is given 1092 * we use the old value of 8 to avoid reducing the max. 1093 * entries. */ 1094 max_factor = 4; 1095 } 1096 nf_conntrack_hash = nf_ct_alloc_hashtable(&nf_conntrack_htable_size, 1097 &nf_conntrack_vmalloc); 1098 if (!nf_conntrack_hash) { 1099 printk(KERN_ERR "Unable to create nf_conntrack_hash\n"); 1100 goto err_out; 1101 } 1102 1103 nf_conntrack_max = max_factor * nf_conntrack_htable_size; 1104 1105 printk("nf_conntrack version %s (%u buckets, %d max)\n", 1106 NF_CONNTRACK_VERSION, nf_conntrack_htable_size, 1107 nf_conntrack_max); 1108 1109 nf_conntrack_cachep = kmem_cache_create("nf_conntrack", 1110 sizeof(struct nf_conn), 1111 0, 0, NULL, NULL); 1112 if (!nf_conntrack_cachep) { 1113 printk(KERN_ERR "Unable to create nf_conn slab cache\n"); 1114 goto err_free_hash; 1115 } 1116 1117 ret = nf_conntrack_proto_init(); 1118 if (ret < 0) 1119 goto err_free_conntrack_slab; 1120 1121 ret = nf_conntrack_expect_init(); 1122 if (ret < 0) 1123 goto out_fini_proto; 1124 1125 ret = nf_conntrack_helper_init(); 1126 if (ret < 0) 1127 goto out_fini_expect; 1128 1129 /* For use by REJECT target */ 1130 rcu_assign_pointer(ip_ct_attach, __nf_conntrack_attach); 1131 rcu_assign_pointer(nf_ct_destroy, destroy_conntrack); 1132 1133 /* Set up fake conntrack: 1134 - to never be deleted, not in any hashes */ 1135 atomic_set(&nf_conntrack_untracked.ct_general.use, 1); 1136 /* - and look it like as a confirmed connection */ 1137 set_bit(IPS_CONFIRMED_BIT, &nf_conntrack_untracked.status); 1138 1139 return ret; 1140 1141out_fini_expect: 1142 nf_conntrack_expect_fini(); 1143out_fini_proto: 1144 nf_conntrack_proto_fini(); 1145err_free_conntrack_slab: 1146 kmem_cache_destroy(nf_conntrack_cachep); 1147err_free_hash: 1148 nf_ct_free_hashtable(nf_conntrack_hash, nf_conntrack_vmalloc, 1149 nf_conntrack_htable_size); 1150err_out: 1151 return -ENOMEM; 1152} 1153