nf_conntrack_core.c revision ffc30690480bdd337e4914302b926d24870b56b2
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 117nf_ct_invert_tuple(struct nf_conntrack_tuple *inverse, 118 const struct nf_conntrack_tuple *orig, 119 const struct nf_conntrack_l3proto *l3proto, 120 const struct nf_conntrack_l4proto *l4proto) 121{ 122 NF_CT_TUPLE_U_BLANK(inverse); 123 124 inverse->src.l3num = orig->src.l3num; 125 if (l3proto->invert_tuple(inverse, orig) == 0) 126 return 0; 127 128 inverse->dst.dir = !orig->dst.dir; 129 130 inverse->dst.protonum = orig->dst.protonum; 131 return l4proto->invert_tuple(inverse, orig); 132} 133EXPORT_SYMBOL_GPL(nf_ct_invert_tuple); 134 135static void 136clean_from_lists(struct nf_conn *ct) 137{ 138 pr_debug("clean_from_lists(%p)\n", ct); 139 hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode); 140 hlist_del(&ct->tuplehash[IP_CT_DIR_REPLY].hnode); 141 142 /* Destroy all pending expectations */ 143 nf_ct_remove_expectations(ct); 144} 145 146static void 147destroy_conntrack(struct nf_conntrack *nfct) 148{ 149 struct nf_conn *ct = (struct nf_conn *)nfct; 150 struct nf_conntrack_l4proto *l4proto; 151 152 pr_debug("destroy_conntrack(%p)\n", ct); 153 NF_CT_ASSERT(atomic_read(&nfct->use) == 0); 154 NF_CT_ASSERT(!timer_pending(&ct->timeout)); 155 156 nf_conntrack_event(IPCT_DESTROY, ct); 157 set_bit(IPS_DYING_BIT, &ct->status); 158 159 /* To make sure we don't get any weird locking issues here: 160 * destroy_conntrack() MUST NOT be called with a write lock 161 * to nf_conntrack_lock!!! -HW */ 162 rcu_read_lock(); 163 l4proto = __nf_ct_l4proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.l3num, 164 ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum); 165 if (l4proto && l4proto->destroy) 166 l4proto->destroy(ct); 167 168 nf_ct_ext_destroy(ct); 169 170 rcu_read_unlock(); 171 172 write_lock_bh(&nf_conntrack_lock); 173 /* Expectations will have been removed in clean_from_lists, 174 * except TFTP can create an expectation on the first packet, 175 * before connection is in the list, so we need to clean here, 176 * too. */ 177 nf_ct_remove_expectations(ct); 178 179 /* We overload first tuple to link into unconfirmed list. */ 180 if (!nf_ct_is_confirmed(ct)) { 181 BUG_ON(hlist_unhashed(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode)); 182 hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode); 183 } 184 185 NF_CT_STAT_INC(delete); 186 write_unlock_bh(&nf_conntrack_lock); 187 188 if (ct->master) 189 nf_ct_put(ct->master); 190 191 pr_debug("destroy_conntrack: returning ct=%p to slab\n", ct); 192 nf_conntrack_free(ct); 193} 194 195static void death_by_timeout(unsigned long ul_conntrack) 196{ 197 struct nf_conn *ct = (void *)ul_conntrack; 198 struct nf_conn_help *help = nfct_help(ct); 199 struct nf_conntrack_helper *helper; 200 201 if (help) { 202 rcu_read_lock(); 203 helper = rcu_dereference(help->helper); 204 if (helper && helper->destroy) 205 helper->destroy(ct); 206 rcu_read_unlock(); 207 } 208 209 write_lock_bh(&nf_conntrack_lock); 210 /* Inside lock so preempt is disabled on module removal path. 211 * Otherwise we can get spurious warnings. */ 212 NF_CT_STAT_INC(delete_list); 213 clean_from_lists(ct); 214 write_unlock_bh(&nf_conntrack_lock); 215 nf_ct_put(ct); 216} 217 218struct nf_conntrack_tuple_hash * 219__nf_conntrack_find(const struct nf_conntrack_tuple *tuple, 220 const struct nf_conn *ignored_conntrack) 221{ 222 struct nf_conntrack_tuple_hash *h; 223 struct hlist_node *n; 224 unsigned int hash = hash_conntrack(tuple); 225 226 hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode) { 227 if (nf_ct_tuplehash_to_ctrack(h) != ignored_conntrack && 228 nf_ct_tuple_equal(tuple, &h->tuple)) { 229 NF_CT_STAT_INC(found); 230 return h; 231 } 232 NF_CT_STAT_INC(searched); 233 } 234 235 return NULL; 236} 237EXPORT_SYMBOL_GPL(__nf_conntrack_find); 238 239/* Find a connection corresponding to a tuple. */ 240struct nf_conntrack_tuple_hash * 241nf_conntrack_find_get(const struct nf_conntrack_tuple *tuple) 242{ 243 struct nf_conntrack_tuple_hash *h; 244 245 read_lock_bh(&nf_conntrack_lock); 246 h = __nf_conntrack_find(tuple, NULL); 247 if (h) 248 atomic_inc(&nf_ct_tuplehash_to_ctrack(h)->ct_general.use); 249 read_unlock_bh(&nf_conntrack_lock); 250 251 return h; 252} 253EXPORT_SYMBOL_GPL(nf_conntrack_find_get); 254 255static void __nf_conntrack_hash_insert(struct nf_conn *ct, 256 unsigned int hash, 257 unsigned int repl_hash) 258{ 259 ct->id = ++nf_conntrack_next_id; 260 hlist_add_head(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode, 261 &nf_conntrack_hash[hash]); 262 hlist_add_head(&ct->tuplehash[IP_CT_DIR_REPLY].hnode, 263 &nf_conntrack_hash[repl_hash]); 264} 265 266void nf_conntrack_hash_insert(struct nf_conn *ct) 267{ 268 unsigned int hash, repl_hash; 269 270 hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); 271 repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); 272 273 write_lock_bh(&nf_conntrack_lock); 274 __nf_conntrack_hash_insert(ct, hash, repl_hash); 275 write_unlock_bh(&nf_conntrack_lock); 276} 277EXPORT_SYMBOL_GPL(nf_conntrack_hash_insert); 278 279/* Confirm a connection given skb; places it in hash table */ 280int 281__nf_conntrack_confirm(struct sk_buff **pskb) 282{ 283 unsigned int hash, repl_hash; 284 struct nf_conntrack_tuple_hash *h; 285 struct nf_conn *ct; 286 struct nf_conn_help *help; 287 struct hlist_node *n; 288 enum ip_conntrack_info ctinfo; 289 290 ct = nf_ct_get(*pskb, &ctinfo); 291 292 /* ipt_REJECT uses nf_conntrack_attach to attach related 293 ICMP/TCP RST packets in other direction. Actual packet 294 which created connection will be IP_CT_NEW or for an 295 expected connection, IP_CT_RELATED. */ 296 if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) 297 return NF_ACCEPT; 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 /* We're not in hash table, and we refuse to set up related 303 connections for unconfirmed conns. But packet copies and 304 REJECT will give spurious warnings here. */ 305 /* NF_CT_ASSERT(atomic_read(&ct->ct_general.use) == 1); */ 306 307 /* No external references means noone else could have 308 confirmed us. */ 309 NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); 310 pr_debug("Confirming conntrack %p\n", ct); 311 312 write_lock_bh(&nf_conntrack_lock); 313 314 /* See if there's one in the list already, including reverse: 315 NAT could have grabbed it without realizing, since we're 316 not in the hash. If there is, we lost race. */ 317 hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode) 318 if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, 319 &h->tuple)) 320 goto out; 321 hlist_for_each_entry(h, n, &nf_conntrack_hash[repl_hash], hnode) 322 if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_REPLY].tuple, 323 &h->tuple)) 324 goto out; 325 326 /* Remove from unconfirmed list */ 327 hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode); 328 329 __nf_conntrack_hash_insert(ct, hash, repl_hash); 330 /* Timer relative to confirmation time, not original 331 setting time, otherwise we'd get timer wrap in 332 weird delay cases. */ 333 ct->timeout.expires += jiffies; 334 add_timer(&ct->timeout); 335 atomic_inc(&ct->ct_general.use); 336 set_bit(IPS_CONFIRMED_BIT, &ct->status); 337 NF_CT_STAT_INC(insert); 338 write_unlock_bh(&nf_conntrack_lock); 339 help = nfct_help(ct); 340 if (help && help->helper) 341 nf_conntrack_event_cache(IPCT_HELPER, *pskb); 342#ifdef CONFIG_NF_NAT_NEEDED 343 if (test_bit(IPS_SRC_NAT_DONE_BIT, &ct->status) || 344 test_bit(IPS_DST_NAT_DONE_BIT, &ct->status)) 345 nf_conntrack_event_cache(IPCT_NATINFO, *pskb); 346#endif 347 nf_conntrack_event_cache(master_ct(ct) ? 348 IPCT_RELATED : IPCT_NEW, *pskb); 349 return NF_ACCEPT; 350 351out: 352 NF_CT_STAT_INC(insert_failed); 353 write_unlock_bh(&nf_conntrack_lock); 354 return NF_DROP; 355} 356EXPORT_SYMBOL_GPL(__nf_conntrack_confirm); 357 358/* Returns true if a connection correspondings to the tuple (required 359 for NAT). */ 360int 361nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple, 362 const struct nf_conn *ignored_conntrack) 363{ 364 struct nf_conntrack_tuple_hash *h; 365 366 read_lock_bh(&nf_conntrack_lock); 367 h = __nf_conntrack_find(tuple, ignored_conntrack); 368 read_unlock_bh(&nf_conntrack_lock); 369 370 return h != NULL; 371} 372EXPORT_SYMBOL_GPL(nf_conntrack_tuple_taken); 373 374#define NF_CT_EVICTION_RANGE 8 375 376/* There's a small race here where we may free a just-assured 377 connection. Too bad: we're in trouble anyway. */ 378static int early_drop(unsigned int hash) 379{ 380 /* Use oldest entry, which is roughly LRU */ 381 struct nf_conntrack_tuple_hash *h; 382 struct nf_conn *ct = NULL, *tmp; 383 struct hlist_node *n; 384 unsigned int i, cnt = 0; 385 int dropped = 0; 386 387 read_lock_bh(&nf_conntrack_lock); 388 for (i = 0; i < nf_conntrack_htable_size; i++) { 389 hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode) { 390 tmp = nf_ct_tuplehash_to_ctrack(h); 391 if (!test_bit(IPS_ASSURED_BIT, &tmp->status)) 392 ct = tmp; 393 cnt++; 394 } 395 if (ct || cnt >= NF_CT_EVICTION_RANGE) 396 break; 397 hash = (hash + 1) % nf_conntrack_htable_size; 398 } 399 if (ct) 400 atomic_inc(&ct->ct_general.use); 401 read_unlock_bh(&nf_conntrack_lock); 402 403 if (!ct) 404 return dropped; 405 406 if (del_timer(&ct->timeout)) { 407 death_by_timeout((unsigned long)ct); 408 dropped = 1; 409 NF_CT_STAT_INC_ATOMIC(early_drop); 410 } 411 nf_ct_put(ct); 412 return dropped; 413} 414 415struct nf_conn *nf_conntrack_alloc(const struct nf_conntrack_tuple *orig, 416 const struct nf_conntrack_tuple *repl) 417{ 418 struct nf_conn *conntrack = NULL; 419 420 if (unlikely(!nf_conntrack_hash_rnd_initted)) { 421 get_random_bytes(&nf_conntrack_hash_rnd, 4); 422 nf_conntrack_hash_rnd_initted = 1; 423 } 424 425 /* We don't want any race condition at early drop stage */ 426 atomic_inc(&nf_conntrack_count); 427 428 if (nf_conntrack_max 429 && atomic_read(&nf_conntrack_count) > nf_conntrack_max) { 430 unsigned int hash = hash_conntrack(orig); 431 if (!early_drop(hash)) { 432 atomic_dec(&nf_conntrack_count); 433 if (net_ratelimit()) 434 printk(KERN_WARNING 435 "nf_conntrack: table full, dropping" 436 " packet.\n"); 437 return ERR_PTR(-ENOMEM); 438 } 439 } 440 441 conntrack = kmem_cache_zalloc(nf_conntrack_cachep, GFP_ATOMIC); 442 if (conntrack == NULL) { 443 pr_debug("nf_conntrack_alloc: Can't alloc conntrack.\n"); 444 atomic_dec(&nf_conntrack_count); 445 return ERR_PTR(-ENOMEM); 446 } 447 448 atomic_set(&conntrack->ct_general.use, 1); 449 conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *orig; 450 conntrack->tuplehash[IP_CT_DIR_REPLY].tuple = *repl; 451 /* Don't set timer yet: wait for confirmation */ 452 setup_timer(&conntrack->timeout, death_by_timeout, 453 (unsigned long)conntrack); 454 455 return conntrack; 456} 457EXPORT_SYMBOL_GPL(nf_conntrack_alloc); 458 459void nf_conntrack_free(struct nf_conn *conntrack) 460{ 461 nf_ct_ext_free(conntrack); 462 kmem_cache_free(nf_conntrack_cachep, conntrack); 463 atomic_dec(&nf_conntrack_count); 464} 465EXPORT_SYMBOL_GPL(nf_conntrack_free); 466 467/* Allocate a new conntrack: we return -ENOMEM if classification 468 failed due to stress. Otherwise it really is unclassifiable. */ 469static struct nf_conntrack_tuple_hash * 470init_conntrack(const struct nf_conntrack_tuple *tuple, 471 struct nf_conntrack_l3proto *l3proto, 472 struct nf_conntrack_l4proto *l4proto, 473 struct sk_buff *skb, 474 unsigned int dataoff) 475{ 476 struct nf_conn *conntrack; 477 struct nf_conn_help *help; 478 struct nf_conntrack_tuple repl_tuple; 479 struct nf_conntrack_expect *exp; 480 481 if (!nf_ct_invert_tuple(&repl_tuple, tuple, l3proto, l4proto)) { 482 pr_debug("Can't invert tuple.\n"); 483 return NULL; 484 } 485 486 conntrack = nf_conntrack_alloc(tuple, &repl_tuple); 487 if (conntrack == NULL || IS_ERR(conntrack)) { 488 pr_debug("Can't allocate conntrack.\n"); 489 return (struct nf_conntrack_tuple_hash *)conntrack; 490 } 491 492 if (!l4proto->new(conntrack, skb, dataoff)) { 493 nf_conntrack_free(conntrack); 494 pr_debug("init conntrack: can't track with proto module\n"); 495 return NULL; 496 } 497 498 write_lock_bh(&nf_conntrack_lock); 499 exp = nf_ct_find_expectation(tuple); 500 if (exp) { 501 pr_debug("conntrack: expectation arrives ct=%p exp=%p\n", 502 conntrack, exp); 503 /* Welcome, Mr. Bond. We've been expecting you... */ 504 __set_bit(IPS_EXPECTED_BIT, &conntrack->status); 505 conntrack->master = exp->master; 506 if (exp->helper) { 507 help = nf_ct_helper_ext_add(conntrack, GFP_ATOMIC); 508 if (help) 509 rcu_assign_pointer(help->helper, exp->helper); 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_helper_ext_add(conntrack, GFP_ATOMIC); 526 if (help) 527 rcu_assign_pointer(help->helper, helper); 528 } 529 NF_CT_STAT_INC(new); 530 } 531 532 /* Overload tuple linked list to put us in unconfirmed list. */ 533 hlist_add_head(&conntrack->tuplehash[IP_CT_DIR_ORIGINAL].hnode, 534 &unconfirmed); 535 536 write_unlock_bh(&nf_conntrack_lock); 537 538 if (exp) { 539 if (exp->expectfn) 540 exp->expectfn(conntrack, exp); 541 nf_ct_expect_put(exp); 542 } 543 544 return &conntrack->tuplehash[IP_CT_DIR_ORIGINAL]; 545} 546 547/* On success, returns conntrack ptr, sets skb->nfct and ctinfo */ 548static inline struct nf_conn * 549resolve_normal_ct(struct sk_buff *skb, 550 unsigned int dataoff, 551 u_int16_t l3num, 552 u_int8_t protonum, 553 struct nf_conntrack_l3proto *l3proto, 554 struct nf_conntrack_l4proto *l4proto, 555 int *set_reply, 556 enum ip_conntrack_info *ctinfo) 557{ 558 struct nf_conntrack_tuple tuple; 559 struct nf_conntrack_tuple_hash *h; 560 struct nf_conn *ct; 561 562 if (!nf_ct_get_tuple(skb, skb_network_offset(skb), 563 dataoff, l3num, protonum, &tuple, l3proto, 564 l4proto)) { 565 pr_debug("resolve_normal_ct: Can't get tuple\n"); 566 return NULL; 567 } 568 569 /* look for tuple match */ 570 h = nf_conntrack_find_get(&tuple); 571 if (!h) { 572 h = init_conntrack(&tuple, l3proto, l4proto, skb, dataoff); 573 if (!h) 574 return NULL; 575 if (IS_ERR(h)) 576 return (void *)h; 577 } 578 ct = nf_ct_tuplehash_to_ctrack(h); 579 580 /* It exists; we have (non-exclusive) reference. */ 581 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) { 582 *ctinfo = IP_CT_ESTABLISHED + IP_CT_IS_REPLY; 583 /* Please set reply bit if this packet OK */ 584 *set_reply = 1; 585 } else { 586 /* Once we've had two way comms, always ESTABLISHED. */ 587 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { 588 pr_debug("nf_conntrack_in: normal packet for %p\n", ct); 589 *ctinfo = IP_CT_ESTABLISHED; 590 } else if (test_bit(IPS_EXPECTED_BIT, &ct->status)) { 591 pr_debug("nf_conntrack_in: related packet for %p\n", 592 ct); 593 *ctinfo = IP_CT_RELATED; 594 } else { 595 pr_debug("nf_conntrack_in: new packet for %p\n", ct); 596 *ctinfo = IP_CT_NEW; 597 } 598 *set_reply = 0; 599 } 600 skb->nfct = &ct->ct_general; 601 skb->nfctinfo = *ctinfo; 602 return ct; 603} 604 605unsigned int 606nf_conntrack_in(int pf, unsigned int hooknum, struct sk_buff **pskb) 607{ 608 struct nf_conn *ct; 609 enum ip_conntrack_info ctinfo; 610 struct nf_conntrack_l3proto *l3proto; 611 struct nf_conntrack_l4proto *l4proto; 612 unsigned int dataoff; 613 u_int8_t protonum; 614 int set_reply = 0; 615 int ret; 616 617 /* Previously seen (loopback or untracked)? Ignore. */ 618 if ((*pskb)->nfct) { 619 NF_CT_STAT_INC_ATOMIC(ignore); 620 return NF_ACCEPT; 621 } 622 623 /* rcu_read_lock()ed by nf_hook_slow */ 624 l3proto = __nf_ct_l3proto_find((u_int16_t)pf); 625 ret = l3proto->get_l4proto(*pskb, skb_network_offset(*pskb), 626 &dataoff, &protonum); 627 if (ret <= 0) { 628 pr_debug("not prepared to track yet or error occured\n"); 629 NF_CT_STAT_INC_ATOMIC(error); 630 NF_CT_STAT_INC_ATOMIC(invalid); 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 pr_debug("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 pr_debug("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_helper_ext_add(ct, GFP_ATOMIC); 723 if (help == NULL) 724 goto out; 725 } else { 726 memset(&help->help, 0, sizeof(help->help)); 727 } 728 729 rcu_assign_pointer(help->helper, helper); 730out: 731 write_unlock_bh(&nf_conntrack_lock); 732} 733EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply); 734 735/* Refresh conntrack for this many jiffies and do accounting if do_acct is 1 */ 736void __nf_ct_refresh_acct(struct nf_conn *ct, 737 enum ip_conntrack_info ctinfo, 738 const struct sk_buff *skb, 739 unsigned long extra_jiffies, 740 int do_acct) 741{ 742 int event = 0; 743 744 NF_CT_ASSERT(ct->timeout.data == (unsigned long)ct); 745 NF_CT_ASSERT(skb); 746 747 write_lock_bh(&nf_conntrack_lock); 748 749 /* Only update if this is not a fixed timeout */ 750 if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status)) { 751 write_unlock_bh(&nf_conntrack_lock); 752 return; 753 } 754 755 /* If not in hash table, timer will not be active yet */ 756 if (!nf_ct_is_confirmed(ct)) { 757 ct->timeout.expires = extra_jiffies; 758 event = IPCT_REFRESH; 759 } else { 760 unsigned long newtime = jiffies + extra_jiffies; 761 762 /* Only update the timeout if the new timeout is at least 763 HZ jiffies from the old timeout. Need del_timer for race 764 avoidance (may already be dying). */ 765 if (newtime - ct->timeout.expires >= HZ 766 && del_timer(&ct->timeout)) { 767 ct->timeout.expires = newtime; 768 add_timer(&ct->timeout); 769 event = IPCT_REFRESH; 770 } 771 } 772 773#ifdef CONFIG_NF_CT_ACCT 774 if (do_acct) { 775 ct->counters[CTINFO2DIR(ctinfo)].packets++; 776 ct->counters[CTINFO2DIR(ctinfo)].bytes += 777 skb->len - skb_network_offset(skb); 778 779 if ((ct->counters[CTINFO2DIR(ctinfo)].packets & 0x80000000) 780 || (ct->counters[CTINFO2DIR(ctinfo)].bytes & 0x80000000)) 781 event |= IPCT_COUNTER_FILLING; 782 } 783#endif 784 785 write_unlock_bh(&nf_conntrack_lock); 786 787 /* must be unlocked when calling event cache */ 788 if (event) 789 nf_conntrack_event_cache(event, skb); 790} 791EXPORT_SYMBOL_GPL(__nf_ct_refresh_acct); 792 793#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE) 794 795#include <linux/netfilter/nfnetlink.h> 796#include <linux/netfilter/nfnetlink_conntrack.h> 797#include <linux/mutex.h> 798 799 800/* Generic function for tcp/udp/sctp/dccp and alike. This needs to be 801 * in ip_conntrack_core, since we don't want the protocols to autoload 802 * or depend on ctnetlink */ 803int nf_ct_port_tuple_to_nfattr(struct sk_buff *skb, 804 const struct nf_conntrack_tuple *tuple) 805{ 806 NFA_PUT(skb, CTA_PROTO_SRC_PORT, sizeof(u_int16_t), 807 &tuple->src.u.tcp.port); 808 NFA_PUT(skb, CTA_PROTO_DST_PORT, sizeof(u_int16_t), 809 &tuple->dst.u.tcp.port); 810 return 0; 811 812nfattr_failure: 813 return -1; 814} 815EXPORT_SYMBOL_GPL(nf_ct_port_tuple_to_nfattr); 816 817static const size_t cta_min_proto[CTA_PROTO_MAX] = { 818 [CTA_PROTO_SRC_PORT-1] = sizeof(u_int16_t), 819 [CTA_PROTO_DST_PORT-1] = sizeof(u_int16_t) 820}; 821 822int nf_ct_port_nfattr_to_tuple(struct nfattr *tb[], 823 struct nf_conntrack_tuple *t) 824{ 825 if (!tb[CTA_PROTO_SRC_PORT-1] || !tb[CTA_PROTO_DST_PORT-1]) 826 return -EINVAL; 827 828 if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto)) 829 return -EINVAL; 830 831 t->src.u.tcp.port = *(__be16 *)NFA_DATA(tb[CTA_PROTO_SRC_PORT-1]); 832 t->dst.u.tcp.port = *(__be16 *)NFA_DATA(tb[CTA_PROTO_DST_PORT-1]); 833 834 return 0; 835} 836EXPORT_SYMBOL_GPL(nf_ct_port_nfattr_to_tuple); 837#endif 838 839/* Used by ipt_REJECT and ip6t_REJECT. */ 840void __nf_conntrack_attach(struct sk_buff *nskb, struct sk_buff *skb) 841{ 842 struct nf_conn *ct; 843 enum ip_conntrack_info ctinfo; 844 845 /* This ICMP is in reverse direction to the packet which caused it */ 846 ct = nf_ct_get(skb, &ctinfo); 847 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) 848 ctinfo = IP_CT_RELATED + IP_CT_IS_REPLY; 849 else 850 ctinfo = IP_CT_RELATED; 851 852 /* Attach to new skbuff, and increment count */ 853 nskb->nfct = &ct->ct_general; 854 nskb->nfctinfo = ctinfo; 855 nf_conntrack_get(nskb->nfct); 856} 857EXPORT_SYMBOL_GPL(__nf_conntrack_attach); 858 859static inline int 860do_iter(const struct nf_conntrack_tuple_hash *i, 861 int (*iter)(struct nf_conn *i, void *data), 862 void *data) 863{ 864 return iter(nf_ct_tuplehash_to_ctrack(i), data); 865} 866 867/* Bring out ya dead! */ 868static struct nf_conn * 869get_next_corpse(int (*iter)(struct nf_conn *i, void *data), 870 void *data, unsigned int *bucket) 871{ 872 struct nf_conntrack_tuple_hash *h; 873 struct nf_conn *ct; 874 struct hlist_node *n; 875 876 write_lock_bh(&nf_conntrack_lock); 877 for (; *bucket < nf_conntrack_htable_size; (*bucket)++) { 878 hlist_for_each_entry(h, n, &nf_conntrack_hash[*bucket], hnode) { 879 ct = nf_ct_tuplehash_to_ctrack(h); 880 if (iter(ct, data)) 881 goto found; 882 } 883 } 884 hlist_for_each_entry(h, n, &unconfirmed, hnode) { 885 ct = nf_ct_tuplehash_to_ctrack(h); 886 if (iter(ct, data)) 887 set_bit(IPS_DYING_BIT, &ct->status); 888 } 889 write_unlock_bh(&nf_conntrack_lock); 890 return NULL; 891found: 892 atomic_inc(&ct->ct_general.use); 893 write_unlock_bh(&nf_conntrack_lock); 894 return ct; 895} 896 897void 898nf_ct_iterate_cleanup(int (*iter)(struct nf_conn *i, void *data), void *data) 899{ 900 struct nf_conn *ct; 901 unsigned int bucket = 0; 902 903 while ((ct = get_next_corpse(iter, data, &bucket)) != NULL) { 904 /* Time to push up daises... */ 905 if (del_timer(&ct->timeout)) 906 death_by_timeout((unsigned long)ct); 907 /* ... else the timer will get him soon. */ 908 909 nf_ct_put(ct); 910 } 911} 912EXPORT_SYMBOL_GPL(nf_ct_iterate_cleanup); 913 914static int kill_all(struct nf_conn *i, void *data) 915{ 916 return 1; 917} 918 919void nf_ct_free_hashtable(struct hlist_head *hash, int vmalloced, int size) 920{ 921 if (vmalloced) 922 vfree(hash); 923 else 924 free_pages((unsigned long)hash, 925 get_order(sizeof(struct hlist_head) * size)); 926} 927EXPORT_SYMBOL_GPL(nf_ct_free_hashtable); 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 nf_ct_free_hashtable(nf_conntrack_hash, nf_conntrack_vmalloc, 961 nf_conntrack_htable_size); 962 963 nf_conntrack_proto_fini(); 964 nf_conntrack_helper_fini(); 965 nf_conntrack_expect_fini(); 966} 967 968struct hlist_head *nf_ct_alloc_hashtable(int *sizep, int *vmalloced) 969{ 970 struct hlist_head *hash; 971 unsigned int size, i; 972 973 *vmalloced = 0; 974 975 size = *sizep = roundup(*sizep, PAGE_SIZE / sizeof(struct hlist_head)); 976 hash = (void*)__get_free_pages(GFP_KERNEL, 977 get_order(sizeof(struct hlist_head) 978 * size)); 979 if (!hash) { 980 *vmalloced = 1; 981 printk(KERN_WARNING "nf_conntrack: falling back to vmalloc.\n"); 982 hash = vmalloc(sizeof(struct hlist_head) * size); 983 } 984 985 if (hash) 986 for (i = 0; i < size; i++) 987 INIT_HLIST_HEAD(&hash[i]); 988 989 return hash; 990} 991EXPORT_SYMBOL_GPL(nf_ct_alloc_hashtable); 992 993int set_hashsize(const char *val, struct kernel_param *kp) 994{ 995 int i, bucket, hashsize, vmalloced; 996 int old_vmalloced, old_size; 997 int rnd; 998 struct hlist_head *hash, *old_hash; 999 struct nf_conntrack_tuple_hash *h; 1000 1001 /* On boot, we can set this without any fancy locking. */ 1002 if (!nf_conntrack_htable_size) 1003 return param_set_uint(val, kp); 1004 1005 hashsize = simple_strtol(val, NULL, 0); 1006 if (!hashsize) 1007 return -EINVAL; 1008 1009 hash = nf_ct_alloc_hashtable(&hashsize, &vmalloced); 1010 if (!hash) 1011 return -ENOMEM; 1012 1013 /* We have to rehahs for the new table anyway, so we also can 1014 * use a newrandom seed */ 1015 get_random_bytes(&rnd, 4); 1016 1017 write_lock_bh(&nf_conntrack_lock); 1018 for (i = 0; i < nf_conntrack_htable_size; i++) { 1019 while (!hlist_empty(&nf_conntrack_hash[i])) { 1020 h = hlist_entry(nf_conntrack_hash[i].first, 1021 struct nf_conntrack_tuple_hash, hnode); 1022 hlist_del(&h->hnode); 1023 bucket = __hash_conntrack(&h->tuple, hashsize, rnd); 1024 hlist_add_head(&h->hnode, &hash[bucket]); 1025 } 1026 } 1027 old_size = nf_conntrack_htable_size; 1028 old_vmalloced = nf_conntrack_vmalloc; 1029 old_hash = nf_conntrack_hash; 1030 1031 nf_conntrack_htable_size = hashsize; 1032 nf_conntrack_vmalloc = vmalloced; 1033 nf_conntrack_hash = hash; 1034 nf_conntrack_hash_rnd = rnd; 1035 write_unlock_bh(&nf_conntrack_lock); 1036 1037 nf_ct_free_hashtable(old_hash, old_vmalloced, old_size); 1038 return 0; 1039} 1040 1041module_param_call(hashsize, set_hashsize, param_get_uint, 1042 &nf_conntrack_htable_size, 0600); 1043 1044int __init nf_conntrack_init(void) 1045{ 1046 int max_factor = 8; 1047 int ret; 1048 1049 /* Idea from tcp.c: use 1/16384 of memory. On i386: 32MB 1050 * machine has 512 buckets. >= 1GB machines have 16384 buckets. */ 1051 if (!nf_conntrack_htable_size) { 1052 nf_conntrack_htable_size 1053 = (((num_physpages << PAGE_SHIFT) / 16384) 1054 / sizeof(struct hlist_head)); 1055 if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE)) 1056 nf_conntrack_htable_size = 16384; 1057 if (nf_conntrack_htable_size < 32) 1058 nf_conntrack_htable_size = 32; 1059 1060 /* Use a max. factor of four by default to get the same max as 1061 * with the old struct list_heads. When a table size is given 1062 * we use the old value of 8 to avoid reducing the max. 1063 * entries. */ 1064 max_factor = 4; 1065 } 1066 nf_conntrack_hash = nf_ct_alloc_hashtable(&nf_conntrack_htable_size, 1067 &nf_conntrack_vmalloc); 1068 if (!nf_conntrack_hash) { 1069 printk(KERN_ERR "Unable to create nf_conntrack_hash\n"); 1070 goto err_out; 1071 } 1072 1073 nf_conntrack_max = max_factor * nf_conntrack_htable_size; 1074 1075 printk("nf_conntrack version %s (%u buckets, %d max)\n", 1076 NF_CONNTRACK_VERSION, nf_conntrack_htable_size, 1077 nf_conntrack_max); 1078 1079 nf_conntrack_cachep = kmem_cache_create("nf_conntrack", 1080 sizeof(struct nf_conn), 1081 0, 0, NULL, NULL); 1082 if (!nf_conntrack_cachep) { 1083 printk(KERN_ERR "Unable to create nf_conn slab cache\n"); 1084 goto err_free_hash; 1085 } 1086 1087 ret = nf_conntrack_proto_init(); 1088 if (ret < 0) 1089 goto err_free_conntrack_slab; 1090 1091 ret = nf_conntrack_expect_init(); 1092 if (ret < 0) 1093 goto out_fini_proto; 1094 1095 ret = nf_conntrack_helper_init(); 1096 if (ret < 0) 1097 goto out_fini_expect; 1098 1099 /* For use by REJECT target */ 1100 rcu_assign_pointer(ip_ct_attach, __nf_conntrack_attach); 1101 rcu_assign_pointer(nf_ct_destroy, destroy_conntrack); 1102 1103 /* Set up fake conntrack: 1104 - to never be deleted, not in any hashes */ 1105 atomic_set(&nf_conntrack_untracked.ct_general.use, 1); 1106 /* - and look it like as a confirmed connection */ 1107 set_bit(IPS_CONFIRMED_BIT, &nf_conntrack_untracked.status); 1108 1109 return ret; 1110 1111out_fini_expect: 1112 nf_conntrack_expect_fini(); 1113out_fini_proto: 1114 nf_conntrack_proto_fini(); 1115err_free_conntrack_slab: 1116 kmem_cache_destroy(nf_conntrack_cachep); 1117err_free_hash: 1118 nf_ct_free_hashtable(nf_conntrack_hash, nf_conntrack_vmalloc, 1119 nf_conntrack_htable_size); 1120err_out: 1121 return -ENOMEM; 1122} 1123