nf_conntrack_core.c revision 29b67497f256399c4aa2adec27ab7ba24bba44e8
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; 66 67DEFINE_PER_CPU(struct ip_conntrack_stat, nf_conntrack_stat); 68EXPORT_PER_CPU_SYMBOL(nf_conntrack_stat); 69 70static int nf_conntrack_hash_rnd_initted; 71static unsigned int nf_conntrack_hash_rnd; 72 73static u_int32_t __hash_conntrack(const struct nf_conntrack_tuple *tuple, 74 unsigned int size, unsigned int rnd) 75{ 76 unsigned int a, b; 77 78 a = jhash2(tuple->src.u3.all, ARRAY_SIZE(tuple->src.u3.all), 79 (tuple->src.l3num << 16) | tuple->dst.protonum); 80 b = jhash2(tuple->dst.u3.all, ARRAY_SIZE(tuple->dst.u3.all), 81 ((__force __u16)tuple->src.u.all << 16) | 82 (__force __u16)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 hlist_add_head(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode, 290 &nf_conntrack_hash[hash]); 291 hlist_add_head(&ct->tuplehash[IP_CT_DIR_REPLY].hnode, 292 &nf_conntrack_hash[repl_hash]); 293} 294 295void nf_conntrack_hash_insert(struct nf_conn *ct) 296{ 297 unsigned int hash, repl_hash; 298 299 hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); 300 repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); 301 302 write_lock_bh(&nf_conntrack_lock); 303 __nf_conntrack_hash_insert(ct, hash, repl_hash); 304 write_unlock_bh(&nf_conntrack_lock); 305} 306EXPORT_SYMBOL_GPL(nf_conntrack_hash_insert); 307 308/* Confirm a connection given skb; places it in hash table */ 309int 310__nf_conntrack_confirm(struct sk_buff *skb) 311{ 312 unsigned int hash, repl_hash; 313 struct nf_conntrack_tuple_hash *h; 314 struct nf_conn *ct; 315 struct nf_conn_help *help; 316 struct hlist_node *n; 317 enum ip_conntrack_info ctinfo; 318 319 ct = nf_ct_get(skb, &ctinfo); 320 321 /* ipt_REJECT uses nf_conntrack_attach to attach related 322 ICMP/TCP RST packets in other direction. Actual packet 323 which created connection will be IP_CT_NEW or for an 324 expected connection, IP_CT_RELATED. */ 325 if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) 326 return NF_ACCEPT; 327 328 hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); 329 repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); 330 331 /* We're not in hash table, and we refuse to set up related 332 connections for unconfirmed conns. But packet copies and 333 REJECT will give spurious warnings here. */ 334 /* NF_CT_ASSERT(atomic_read(&ct->ct_general.use) == 1); */ 335 336 /* No external references means noone else could have 337 confirmed us. */ 338 NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); 339 pr_debug("Confirming conntrack %p\n", ct); 340 341 write_lock_bh(&nf_conntrack_lock); 342 343 /* See if there's one in the list already, including reverse: 344 NAT could have grabbed it without realizing, since we're 345 not in the hash. If there is, we lost race. */ 346 hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode) 347 if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, 348 &h->tuple)) 349 goto out; 350 hlist_for_each_entry(h, n, &nf_conntrack_hash[repl_hash], hnode) 351 if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_REPLY].tuple, 352 &h->tuple)) 353 goto out; 354 355 /* Remove from unconfirmed list */ 356 hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode); 357 358 __nf_conntrack_hash_insert(ct, hash, repl_hash); 359 /* Timer relative to confirmation time, not original 360 setting time, otherwise we'd get timer wrap in 361 weird delay cases. */ 362 ct->timeout.expires += jiffies; 363 add_timer(&ct->timeout); 364 atomic_inc(&ct->ct_general.use); 365 set_bit(IPS_CONFIRMED_BIT, &ct->status); 366 NF_CT_STAT_INC(insert); 367 write_unlock_bh(&nf_conntrack_lock); 368 help = nfct_help(ct); 369 if (help && help->helper) 370 nf_conntrack_event_cache(IPCT_HELPER, skb); 371#ifdef CONFIG_NF_NAT_NEEDED 372 if (test_bit(IPS_SRC_NAT_DONE_BIT, &ct->status) || 373 test_bit(IPS_DST_NAT_DONE_BIT, &ct->status)) 374 nf_conntrack_event_cache(IPCT_NATINFO, skb); 375#endif 376 nf_conntrack_event_cache(master_ct(ct) ? 377 IPCT_RELATED : IPCT_NEW, skb); 378 return NF_ACCEPT; 379 380out: 381 NF_CT_STAT_INC(insert_failed); 382 write_unlock_bh(&nf_conntrack_lock); 383 return NF_DROP; 384} 385EXPORT_SYMBOL_GPL(__nf_conntrack_confirm); 386 387/* Returns true if a connection correspondings to the tuple (required 388 for NAT). */ 389int 390nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple, 391 const struct nf_conn *ignored_conntrack) 392{ 393 struct nf_conntrack_tuple_hash *h; 394 395 read_lock_bh(&nf_conntrack_lock); 396 h = __nf_conntrack_find(tuple, ignored_conntrack); 397 read_unlock_bh(&nf_conntrack_lock); 398 399 return h != NULL; 400} 401EXPORT_SYMBOL_GPL(nf_conntrack_tuple_taken); 402 403#define NF_CT_EVICTION_RANGE 8 404 405/* There's a small race here where we may free a just-assured 406 connection. Too bad: we're in trouble anyway. */ 407static int early_drop(unsigned int hash) 408{ 409 /* Use oldest entry, which is roughly LRU */ 410 struct nf_conntrack_tuple_hash *h; 411 struct nf_conn *ct = NULL, *tmp; 412 struct hlist_node *n; 413 unsigned int i, cnt = 0; 414 int dropped = 0; 415 416 read_lock_bh(&nf_conntrack_lock); 417 for (i = 0; i < nf_conntrack_htable_size; i++) { 418 hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode) { 419 tmp = nf_ct_tuplehash_to_ctrack(h); 420 if (!test_bit(IPS_ASSURED_BIT, &tmp->status)) 421 ct = tmp; 422 cnt++; 423 } 424 if (ct || cnt >= NF_CT_EVICTION_RANGE) 425 break; 426 hash = (hash + 1) % nf_conntrack_htable_size; 427 } 428 if (ct) 429 atomic_inc(&ct->ct_general.use); 430 read_unlock_bh(&nf_conntrack_lock); 431 432 if (!ct) 433 return dropped; 434 435 if (del_timer(&ct->timeout)) { 436 death_by_timeout((unsigned long)ct); 437 dropped = 1; 438 NF_CT_STAT_INC_ATOMIC(early_drop); 439 } 440 nf_ct_put(ct); 441 return dropped; 442} 443 444struct nf_conn *nf_conntrack_alloc(const struct nf_conntrack_tuple *orig, 445 const struct nf_conntrack_tuple *repl) 446{ 447 struct nf_conn *conntrack = NULL; 448 449 if (unlikely(!nf_conntrack_hash_rnd_initted)) { 450 get_random_bytes(&nf_conntrack_hash_rnd, 4); 451 nf_conntrack_hash_rnd_initted = 1; 452 } 453 454 /* We don't want any race condition at early drop stage */ 455 atomic_inc(&nf_conntrack_count); 456 457 if (nf_conntrack_max 458 && atomic_read(&nf_conntrack_count) > nf_conntrack_max) { 459 unsigned int hash = hash_conntrack(orig); 460 if (!early_drop(hash)) { 461 atomic_dec(&nf_conntrack_count); 462 if (net_ratelimit()) 463 printk(KERN_WARNING 464 "nf_conntrack: table full, dropping" 465 " packet.\n"); 466 return ERR_PTR(-ENOMEM); 467 } 468 } 469 470 conntrack = kmem_cache_zalloc(nf_conntrack_cachep, GFP_ATOMIC); 471 if (conntrack == NULL) { 472 pr_debug("nf_conntrack_alloc: Can't alloc conntrack.\n"); 473 atomic_dec(&nf_conntrack_count); 474 return ERR_PTR(-ENOMEM); 475 } 476 477 atomic_set(&conntrack->ct_general.use, 1); 478 conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *orig; 479 conntrack->tuplehash[IP_CT_DIR_REPLY].tuple = *repl; 480 /* Don't set timer yet: wait for confirmation */ 481 setup_timer(&conntrack->timeout, death_by_timeout, 482 (unsigned long)conntrack); 483 484 return conntrack; 485} 486EXPORT_SYMBOL_GPL(nf_conntrack_alloc); 487 488void nf_conntrack_free(struct nf_conn *conntrack) 489{ 490 nf_ct_ext_free(conntrack); 491 kmem_cache_free(nf_conntrack_cachep, conntrack); 492 atomic_dec(&nf_conntrack_count); 493} 494EXPORT_SYMBOL_GPL(nf_conntrack_free); 495 496/* Allocate a new conntrack: we return -ENOMEM if classification 497 failed due to stress. Otherwise it really is unclassifiable. */ 498static struct nf_conntrack_tuple_hash * 499init_conntrack(const struct nf_conntrack_tuple *tuple, 500 struct nf_conntrack_l3proto *l3proto, 501 struct nf_conntrack_l4proto *l4proto, 502 struct sk_buff *skb, 503 unsigned int dataoff) 504{ 505 struct nf_conn *conntrack; 506 struct nf_conn_help *help; 507 struct nf_conntrack_tuple repl_tuple; 508 struct nf_conntrack_expect *exp; 509 510 if (!nf_ct_invert_tuple(&repl_tuple, tuple, l3proto, l4proto)) { 511 pr_debug("Can't invert tuple.\n"); 512 return NULL; 513 } 514 515 conntrack = nf_conntrack_alloc(tuple, &repl_tuple); 516 if (conntrack == NULL || IS_ERR(conntrack)) { 517 pr_debug("Can't allocate conntrack.\n"); 518 return (struct nf_conntrack_tuple_hash *)conntrack; 519 } 520 521 if (!l4proto->new(conntrack, skb, dataoff)) { 522 nf_conntrack_free(conntrack); 523 pr_debug("init conntrack: can't track with proto module\n"); 524 return NULL; 525 } 526 527 write_lock_bh(&nf_conntrack_lock); 528 exp = nf_ct_find_expectation(tuple); 529 if (exp) { 530 pr_debug("conntrack: expectation arrives ct=%p exp=%p\n", 531 conntrack, exp); 532 /* Welcome, Mr. Bond. We've been expecting you... */ 533 __set_bit(IPS_EXPECTED_BIT, &conntrack->status); 534 conntrack->master = exp->master; 535 if (exp->helper) { 536 help = nf_ct_helper_ext_add(conntrack, GFP_ATOMIC); 537 if (help) 538 rcu_assign_pointer(help->helper, exp->helper); 539 } 540 541#ifdef CONFIG_NF_CONNTRACK_MARK 542 conntrack->mark = exp->master->mark; 543#endif 544#ifdef CONFIG_NF_CONNTRACK_SECMARK 545 conntrack->secmark = exp->master->secmark; 546#endif 547 nf_conntrack_get(&conntrack->master->ct_general); 548 NF_CT_STAT_INC(expect_new); 549 } else { 550 struct nf_conntrack_helper *helper; 551 552 helper = __nf_ct_helper_find(&repl_tuple); 553 if (helper) { 554 help = nf_ct_helper_ext_add(conntrack, GFP_ATOMIC); 555 if (help) 556 rcu_assign_pointer(help->helper, helper); 557 } 558 NF_CT_STAT_INC(new); 559 } 560 561 /* Overload tuple linked list to put us in unconfirmed list. */ 562 hlist_add_head(&conntrack->tuplehash[IP_CT_DIR_ORIGINAL].hnode, 563 &unconfirmed); 564 565 write_unlock_bh(&nf_conntrack_lock); 566 567 if (exp) { 568 if (exp->expectfn) 569 exp->expectfn(conntrack, exp); 570 nf_ct_expect_put(exp); 571 } 572 573 return &conntrack->tuplehash[IP_CT_DIR_ORIGINAL]; 574} 575 576/* On success, returns conntrack ptr, sets skb->nfct and ctinfo */ 577static inline struct nf_conn * 578resolve_normal_ct(struct sk_buff *skb, 579 unsigned int dataoff, 580 u_int16_t l3num, 581 u_int8_t protonum, 582 struct nf_conntrack_l3proto *l3proto, 583 struct nf_conntrack_l4proto *l4proto, 584 int *set_reply, 585 enum ip_conntrack_info *ctinfo) 586{ 587 struct nf_conntrack_tuple tuple; 588 struct nf_conntrack_tuple_hash *h; 589 struct nf_conn *ct; 590 591 if (!nf_ct_get_tuple(skb, skb_network_offset(skb), 592 dataoff, l3num, protonum, &tuple, l3proto, 593 l4proto)) { 594 pr_debug("resolve_normal_ct: Can't get tuple\n"); 595 return NULL; 596 } 597 598 /* look for tuple match */ 599 h = nf_conntrack_find_get(&tuple); 600 if (!h) { 601 h = init_conntrack(&tuple, l3proto, l4proto, skb, dataoff); 602 if (!h) 603 return NULL; 604 if (IS_ERR(h)) 605 return (void *)h; 606 } 607 ct = nf_ct_tuplehash_to_ctrack(h); 608 609 /* It exists; we have (non-exclusive) reference. */ 610 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) { 611 *ctinfo = IP_CT_ESTABLISHED + IP_CT_IS_REPLY; 612 /* Please set reply bit if this packet OK */ 613 *set_reply = 1; 614 } else { 615 /* Once we've had two way comms, always ESTABLISHED. */ 616 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { 617 pr_debug("nf_conntrack_in: normal packet for %p\n", ct); 618 *ctinfo = IP_CT_ESTABLISHED; 619 } else if (test_bit(IPS_EXPECTED_BIT, &ct->status)) { 620 pr_debug("nf_conntrack_in: related packet for %p\n", 621 ct); 622 *ctinfo = IP_CT_RELATED; 623 } else { 624 pr_debug("nf_conntrack_in: new packet for %p\n", ct); 625 *ctinfo = IP_CT_NEW; 626 } 627 *set_reply = 0; 628 } 629 skb->nfct = &ct->ct_general; 630 skb->nfctinfo = *ctinfo; 631 return ct; 632} 633 634unsigned int 635nf_conntrack_in(int pf, unsigned int hooknum, struct sk_buff *skb) 636{ 637 struct nf_conn *ct; 638 enum ip_conntrack_info ctinfo; 639 struct nf_conntrack_l3proto *l3proto; 640 struct nf_conntrack_l4proto *l4proto; 641 unsigned int dataoff; 642 u_int8_t protonum; 643 int set_reply = 0; 644 int ret; 645 646 /* Previously seen (loopback or untracked)? Ignore. */ 647 if (skb->nfct) { 648 NF_CT_STAT_INC_ATOMIC(ignore); 649 return NF_ACCEPT; 650 } 651 652 /* rcu_read_lock()ed by nf_hook_slow */ 653 l3proto = __nf_ct_l3proto_find((u_int16_t)pf); 654 ret = l3proto->get_l4proto(skb, skb_network_offset(skb), 655 &dataoff, &protonum); 656 if (ret <= 0) { 657 pr_debug("not prepared to track yet or error occured\n"); 658 NF_CT_STAT_INC_ATOMIC(error); 659 NF_CT_STAT_INC_ATOMIC(invalid); 660 return -ret; 661 } 662 663 l4proto = __nf_ct_l4proto_find((u_int16_t)pf, protonum); 664 665 /* It may be an special packet, error, unclean... 666 * inverse of the return code tells to the netfilter 667 * core what to do with the packet. */ 668 if (l4proto->error != NULL && 669 (ret = l4proto->error(skb, dataoff, &ctinfo, pf, hooknum)) <= 0) { 670 NF_CT_STAT_INC_ATOMIC(error); 671 NF_CT_STAT_INC_ATOMIC(invalid); 672 return -ret; 673 } 674 675 ct = resolve_normal_ct(skb, dataoff, pf, protonum, l3proto, l4proto, 676 &set_reply, &ctinfo); 677 if (!ct) { 678 /* Not valid part of a connection */ 679 NF_CT_STAT_INC_ATOMIC(invalid); 680 return NF_ACCEPT; 681 } 682 683 if (IS_ERR(ct)) { 684 /* Too stressed to deal. */ 685 NF_CT_STAT_INC_ATOMIC(drop); 686 return NF_DROP; 687 } 688 689 NF_CT_ASSERT(skb->nfct); 690 691 ret = l4proto->packet(ct, skb, dataoff, ctinfo, pf, hooknum); 692 if (ret < 0) { 693 /* Invalid: inverse of the return code tells 694 * the netfilter core what to do */ 695 pr_debug("nf_conntrack_in: Can't track with proto module\n"); 696 nf_conntrack_put(skb->nfct); 697 skb->nfct = NULL; 698 NF_CT_STAT_INC_ATOMIC(invalid); 699 return -ret; 700 } 701 702 if (set_reply && !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status)) 703 nf_conntrack_event_cache(IPCT_STATUS, skb); 704 705 return ret; 706} 707EXPORT_SYMBOL_GPL(nf_conntrack_in); 708 709int nf_ct_invert_tuplepr(struct nf_conntrack_tuple *inverse, 710 const struct nf_conntrack_tuple *orig) 711{ 712 int ret; 713 714 rcu_read_lock(); 715 ret = nf_ct_invert_tuple(inverse, orig, 716 __nf_ct_l3proto_find(orig->src.l3num), 717 __nf_ct_l4proto_find(orig->src.l3num, 718 orig->dst.protonum)); 719 rcu_read_unlock(); 720 return ret; 721} 722EXPORT_SYMBOL_GPL(nf_ct_invert_tuplepr); 723 724/* Alter reply tuple (maybe alter helper). This is for NAT, and is 725 implicitly racy: see __nf_conntrack_confirm */ 726void nf_conntrack_alter_reply(struct nf_conn *ct, 727 const struct nf_conntrack_tuple *newreply) 728{ 729 struct nf_conn_help *help = nfct_help(ct); 730 struct nf_conntrack_helper *helper; 731 732 write_lock_bh(&nf_conntrack_lock); 733 /* Should be unconfirmed, so not in hash table yet */ 734 NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); 735 736 pr_debug("Altering reply tuple of %p to ", ct); 737 NF_CT_DUMP_TUPLE(newreply); 738 739 ct->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply; 740 if (ct->master || (help && help->expecting != 0)) 741 goto out; 742 743 helper = __nf_ct_helper_find(newreply); 744 if (helper == NULL) { 745 if (help) 746 rcu_assign_pointer(help->helper, NULL); 747 goto out; 748 } 749 750 if (help == NULL) { 751 help = nf_ct_helper_ext_add(ct, GFP_ATOMIC); 752 if (help == NULL) 753 goto out; 754 } else { 755 memset(&help->help, 0, sizeof(help->help)); 756 } 757 758 rcu_assign_pointer(help->helper, helper); 759out: 760 write_unlock_bh(&nf_conntrack_lock); 761} 762EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply); 763 764/* Refresh conntrack for this many jiffies and do accounting if do_acct is 1 */ 765void __nf_ct_refresh_acct(struct nf_conn *ct, 766 enum ip_conntrack_info ctinfo, 767 const struct sk_buff *skb, 768 unsigned long extra_jiffies, 769 int do_acct) 770{ 771 int event = 0; 772 773 NF_CT_ASSERT(ct->timeout.data == (unsigned long)ct); 774 NF_CT_ASSERT(skb); 775 776 write_lock_bh(&nf_conntrack_lock); 777 778 /* Only update if this is not a fixed timeout */ 779 if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status)) { 780 write_unlock_bh(&nf_conntrack_lock); 781 return; 782 } 783 784 /* If not in hash table, timer will not be active yet */ 785 if (!nf_ct_is_confirmed(ct)) { 786 ct->timeout.expires = extra_jiffies; 787 event = IPCT_REFRESH; 788 } else { 789 unsigned long newtime = jiffies + extra_jiffies; 790 791 /* Only update the timeout if the new timeout is at least 792 HZ jiffies from the old timeout. Need del_timer for race 793 avoidance (may already be dying). */ 794 if (newtime - ct->timeout.expires >= HZ 795 && del_timer(&ct->timeout)) { 796 ct->timeout.expires = newtime; 797 add_timer(&ct->timeout); 798 event = IPCT_REFRESH; 799 } 800 } 801 802#ifdef CONFIG_NF_CT_ACCT 803 if (do_acct) { 804 ct->counters[CTINFO2DIR(ctinfo)].packets++; 805 ct->counters[CTINFO2DIR(ctinfo)].bytes += 806 skb->len - skb_network_offset(skb); 807 808 if ((ct->counters[CTINFO2DIR(ctinfo)].packets & 0x80000000) 809 || (ct->counters[CTINFO2DIR(ctinfo)].bytes & 0x80000000)) 810 event |= IPCT_COUNTER_FILLING; 811 } 812#endif 813 814 write_unlock_bh(&nf_conntrack_lock); 815 816 /* must be unlocked when calling event cache */ 817 if (event) 818 nf_conntrack_event_cache(event, skb); 819} 820EXPORT_SYMBOL_GPL(__nf_ct_refresh_acct); 821 822#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE) 823 824#include <linux/netfilter/nfnetlink.h> 825#include <linux/netfilter/nfnetlink_conntrack.h> 826#include <linux/mutex.h> 827 828/* Generic function for tcp/udp/sctp/dccp and alike. This needs to be 829 * in ip_conntrack_core, since we don't want the protocols to autoload 830 * or depend on ctnetlink */ 831int nf_ct_port_tuple_to_nlattr(struct sk_buff *skb, 832 const struct nf_conntrack_tuple *tuple) 833{ 834 NLA_PUT(skb, CTA_PROTO_SRC_PORT, sizeof(u_int16_t), 835 &tuple->src.u.tcp.port); 836 NLA_PUT(skb, CTA_PROTO_DST_PORT, sizeof(u_int16_t), 837 &tuple->dst.u.tcp.port); 838 return 0; 839 840nla_put_failure: 841 return -1; 842} 843EXPORT_SYMBOL_GPL(nf_ct_port_tuple_to_nlattr); 844 845const struct nla_policy nf_ct_port_nla_policy[CTA_PROTO_MAX+1] = { 846 [CTA_PROTO_SRC_PORT] = { .type = NLA_U16 }, 847 [CTA_PROTO_DST_PORT] = { .type = NLA_U16 }, 848}; 849EXPORT_SYMBOL_GPL(nf_ct_port_nla_policy); 850 851int nf_ct_port_nlattr_to_tuple(struct nlattr *tb[], 852 struct nf_conntrack_tuple *t) 853{ 854 if (!tb[CTA_PROTO_SRC_PORT] || !tb[CTA_PROTO_DST_PORT]) 855 return -EINVAL; 856 857 t->src.u.tcp.port = *(__be16 *)nla_data(tb[CTA_PROTO_SRC_PORT]); 858 t->dst.u.tcp.port = *(__be16 *)nla_data(tb[CTA_PROTO_DST_PORT]); 859 860 return 0; 861} 862EXPORT_SYMBOL_GPL(nf_ct_port_nlattr_to_tuple); 863#endif 864 865/* Used by ipt_REJECT and ip6t_REJECT. */ 866void __nf_conntrack_attach(struct sk_buff *nskb, struct sk_buff *skb) 867{ 868 struct nf_conn *ct; 869 enum ip_conntrack_info ctinfo; 870 871 /* This ICMP is in reverse direction to the packet which caused it */ 872 ct = nf_ct_get(skb, &ctinfo); 873 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) 874 ctinfo = IP_CT_RELATED + IP_CT_IS_REPLY; 875 else 876 ctinfo = IP_CT_RELATED; 877 878 /* Attach to new skbuff, and increment count */ 879 nskb->nfct = &ct->ct_general; 880 nskb->nfctinfo = ctinfo; 881 nf_conntrack_get(nskb->nfct); 882} 883EXPORT_SYMBOL_GPL(__nf_conntrack_attach); 884 885static inline int 886do_iter(const struct nf_conntrack_tuple_hash *i, 887 int (*iter)(struct nf_conn *i, void *data), 888 void *data) 889{ 890 return iter(nf_ct_tuplehash_to_ctrack(i), data); 891} 892 893/* Bring out ya dead! */ 894static struct nf_conn * 895get_next_corpse(int (*iter)(struct nf_conn *i, void *data), 896 void *data, unsigned int *bucket) 897{ 898 struct nf_conntrack_tuple_hash *h; 899 struct nf_conn *ct; 900 struct hlist_node *n; 901 902 write_lock_bh(&nf_conntrack_lock); 903 for (; *bucket < nf_conntrack_htable_size; (*bucket)++) { 904 hlist_for_each_entry(h, n, &nf_conntrack_hash[*bucket], hnode) { 905 ct = nf_ct_tuplehash_to_ctrack(h); 906 if (iter(ct, data)) 907 goto found; 908 } 909 } 910 hlist_for_each_entry(h, n, &unconfirmed, hnode) { 911 ct = nf_ct_tuplehash_to_ctrack(h); 912 if (iter(ct, data)) 913 set_bit(IPS_DYING_BIT, &ct->status); 914 } 915 write_unlock_bh(&nf_conntrack_lock); 916 return NULL; 917found: 918 atomic_inc(&ct->ct_general.use); 919 write_unlock_bh(&nf_conntrack_lock); 920 return ct; 921} 922 923void 924nf_ct_iterate_cleanup(int (*iter)(struct nf_conn *i, void *data), void *data) 925{ 926 struct nf_conn *ct; 927 unsigned int bucket = 0; 928 929 while ((ct = get_next_corpse(iter, data, &bucket)) != NULL) { 930 /* Time to push up daises... */ 931 if (del_timer(&ct->timeout)) 932 death_by_timeout((unsigned long)ct); 933 /* ... else the timer will get him soon. */ 934 935 nf_ct_put(ct); 936 } 937} 938EXPORT_SYMBOL_GPL(nf_ct_iterate_cleanup); 939 940static int kill_all(struct nf_conn *i, void *data) 941{ 942 return 1; 943} 944 945void nf_ct_free_hashtable(struct hlist_head *hash, int vmalloced, int size) 946{ 947 if (vmalloced) 948 vfree(hash); 949 else 950 free_pages((unsigned long)hash, 951 get_order(sizeof(struct hlist_head) * size)); 952} 953EXPORT_SYMBOL_GPL(nf_ct_free_hashtable); 954 955void nf_conntrack_flush(void) 956{ 957 nf_ct_iterate_cleanup(kill_all, NULL); 958} 959EXPORT_SYMBOL_GPL(nf_conntrack_flush); 960 961/* Mishearing the voices in his head, our hero wonders how he's 962 supposed to kill the mall. */ 963void nf_conntrack_cleanup(void) 964{ 965 rcu_assign_pointer(ip_ct_attach, NULL); 966 967 /* This makes sure all current packets have passed through 968 netfilter framework. Roll on, two-stage module 969 delete... */ 970 synchronize_net(); 971 972 nf_ct_event_cache_flush(); 973 i_see_dead_people: 974 nf_conntrack_flush(); 975 if (atomic_read(&nf_conntrack_count) != 0) { 976 schedule(); 977 goto i_see_dead_people; 978 } 979 /* wait until all references to nf_conntrack_untracked are dropped */ 980 while (atomic_read(&nf_conntrack_untracked.ct_general.use) > 1) 981 schedule(); 982 983 rcu_assign_pointer(nf_ct_destroy, NULL); 984 985 kmem_cache_destroy(nf_conntrack_cachep); 986 nf_ct_free_hashtable(nf_conntrack_hash, nf_conntrack_vmalloc, 987 nf_conntrack_htable_size); 988 989 nf_conntrack_proto_fini(); 990 nf_conntrack_helper_fini(); 991 nf_conntrack_expect_fini(); 992} 993 994struct hlist_head *nf_ct_alloc_hashtable(int *sizep, int *vmalloced) 995{ 996 struct hlist_head *hash; 997 unsigned int size, i; 998 999 *vmalloced = 0; 1000 1001 size = *sizep = roundup(*sizep, PAGE_SIZE / sizeof(struct hlist_head)); 1002 hash = (void*)__get_free_pages(GFP_KERNEL|__GFP_NOWARN, 1003 get_order(sizeof(struct hlist_head) 1004 * size)); 1005 if (!hash) { 1006 *vmalloced = 1; 1007 printk(KERN_WARNING "nf_conntrack: falling back to vmalloc.\n"); 1008 hash = vmalloc(sizeof(struct hlist_head) * size); 1009 } 1010 1011 if (hash) 1012 for (i = 0; i < size; i++) 1013 INIT_HLIST_HEAD(&hash[i]); 1014 1015 return hash; 1016} 1017EXPORT_SYMBOL_GPL(nf_ct_alloc_hashtable); 1018 1019int set_hashsize(const char *val, struct kernel_param *kp) 1020{ 1021 int i, bucket, hashsize, vmalloced; 1022 int old_vmalloced, old_size; 1023 int rnd; 1024 struct hlist_head *hash, *old_hash; 1025 struct nf_conntrack_tuple_hash *h; 1026 1027 /* On boot, we can set this without any fancy locking. */ 1028 if (!nf_conntrack_htable_size) 1029 return param_set_uint(val, kp); 1030 1031 hashsize = simple_strtol(val, NULL, 0); 1032 if (!hashsize) 1033 return -EINVAL; 1034 1035 hash = nf_ct_alloc_hashtable(&hashsize, &vmalloced); 1036 if (!hash) 1037 return -ENOMEM; 1038 1039 /* We have to rehahs for the new table anyway, so we also can 1040 * use a newrandom seed */ 1041 get_random_bytes(&rnd, 4); 1042 1043 write_lock_bh(&nf_conntrack_lock); 1044 for (i = 0; i < nf_conntrack_htable_size; i++) { 1045 while (!hlist_empty(&nf_conntrack_hash[i])) { 1046 h = hlist_entry(nf_conntrack_hash[i].first, 1047 struct nf_conntrack_tuple_hash, hnode); 1048 hlist_del(&h->hnode); 1049 bucket = __hash_conntrack(&h->tuple, hashsize, rnd); 1050 hlist_add_head(&h->hnode, &hash[bucket]); 1051 } 1052 } 1053 old_size = nf_conntrack_htable_size; 1054 old_vmalloced = nf_conntrack_vmalloc; 1055 old_hash = nf_conntrack_hash; 1056 1057 nf_conntrack_htable_size = hashsize; 1058 nf_conntrack_vmalloc = vmalloced; 1059 nf_conntrack_hash = hash; 1060 nf_conntrack_hash_rnd = rnd; 1061 write_unlock_bh(&nf_conntrack_lock); 1062 1063 nf_ct_free_hashtable(old_hash, old_vmalloced, old_size); 1064 return 0; 1065} 1066 1067module_param_call(hashsize, set_hashsize, param_get_uint, 1068 &nf_conntrack_htable_size, 0600); 1069 1070int __init nf_conntrack_init(void) 1071{ 1072 int max_factor = 8; 1073 int ret; 1074 1075 /* Idea from tcp.c: use 1/16384 of memory. On i386: 32MB 1076 * machine has 512 buckets. >= 1GB machines have 16384 buckets. */ 1077 if (!nf_conntrack_htable_size) { 1078 nf_conntrack_htable_size 1079 = (((num_physpages << PAGE_SHIFT) / 16384) 1080 / sizeof(struct hlist_head)); 1081 if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE)) 1082 nf_conntrack_htable_size = 16384; 1083 if (nf_conntrack_htable_size < 32) 1084 nf_conntrack_htable_size = 32; 1085 1086 /* Use a max. factor of four by default to get the same max as 1087 * with the old struct list_heads. When a table size is given 1088 * we use the old value of 8 to avoid reducing the max. 1089 * entries. */ 1090 max_factor = 4; 1091 } 1092 nf_conntrack_hash = nf_ct_alloc_hashtable(&nf_conntrack_htable_size, 1093 &nf_conntrack_vmalloc); 1094 if (!nf_conntrack_hash) { 1095 printk(KERN_ERR "Unable to create nf_conntrack_hash\n"); 1096 goto err_out; 1097 } 1098 1099 nf_conntrack_max = max_factor * nf_conntrack_htable_size; 1100 1101 printk("nf_conntrack version %s (%u buckets, %d max)\n", 1102 NF_CONNTRACK_VERSION, nf_conntrack_htable_size, 1103 nf_conntrack_max); 1104 1105 nf_conntrack_cachep = kmem_cache_create("nf_conntrack", 1106 sizeof(struct nf_conn), 1107 0, 0, NULL); 1108 if (!nf_conntrack_cachep) { 1109 printk(KERN_ERR "Unable to create nf_conn slab cache\n"); 1110 goto err_free_hash; 1111 } 1112 1113 ret = nf_conntrack_proto_init(); 1114 if (ret < 0) 1115 goto err_free_conntrack_slab; 1116 1117 ret = nf_conntrack_expect_init(); 1118 if (ret < 0) 1119 goto out_fini_proto; 1120 1121 ret = nf_conntrack_helper_init(); 1122 if (ret < 0) 1123 goto out_fini_expect; 1124 1125 /* For use by REJECT target */ 1126 rcu_assign_pointer(ip_ct_attach, __nf_conntrack_attach); 1127 rcu_assign_pointer(nf_ct_destroy, destroy_conntrack); 1128 1129 /* Set up fake conntrack: 1130 - to never be deleted, not in any hashes */ 1131 atomic_set(&nf_conntrack_untracked.ct_general.use, 1); 1132 /* - and look it like as a confirmed connection */ 1133 set_bit(IPS_CONFIRMED_BIT, &nf_conntrack_untracked.status); 1134 1135 return ret; 1136 1137out_fini_expect: 1138 nf_conntrack_expect_fini(); 1139out_fini_proto: 1140 nf_conntrack_proto_fini(); 1141err_free_conntrack_slab: 1142 kmem_cache_destroy(nf_conntrack_cachep); 1143err_free_hash: 1144 nf_ct_free_hashtable(nf_conntrack_hash, nf_conntrack_vmalloc, 1145 nf_conntrack_htable_size); 1146err_out: 1147 return -ENOMEM; 1148} 1149