nf_conntrack_core.c revision 6823645d608541c2c69e8a99454936e058c294e0
1/* Connection state tracking for netfilter. This is separated from, 2 but required by, the NAT layer; it can also be used by an iptables 3 extension. */ 4 5/* (C) 1999-2001 Paul `Rusty' Russell 6 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> 7 * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License version 2 as 11 * published by the Free Software Foundation. 12 */ 13 14#include <linux/types.h> 15#include <linux/netfilter.h> 16#include <linux/module.h> 17#include <linux/skbuff.h> 18#include <linux/proc_fs.h> 19#include <linux/vmalloc.h> 20#include <linux/stddef.h> 21#include <linux/slab.h> 22#include <linux/random.h> 23#include <linux/jhash.h> 24#include <linux/err.h> 25#include <linux/percpu.h> 26#include <linux/moduleparam.h> 27#include <linux/notifier.h> 28#include <linux/kernel.h> 29#include <linux/netdevice.h> 30#include <linux/socket.h> 31#include <linux/mm.h> 32 33#include <net/netfilter/nf_conntrack.h> 34#include <net/netfilter/nf_conntrack_l3proto.h> 35#include <net/netfilter/nf_conntrack_l4proto.h> 36#include <net/netfilter/nf_conntrack_expect.h> 37#include <net/netfilter/nf_conntrack_helper.h> 38#include <net/netfilter/nf_conntrack_core.h> 39#include <net/netfilter/nf_conntrack_extend.h> 40 41#define NF_CONNTRACK_VERSION "0.5.0" 42 43#if 0 44#define DEBUGP printk 45#else 46#define DEBUGP(format, args...) 47#endif 48 49DEFINE_RWLOCK(nf_conntrack_lock); 50EXPORT_SYMBOL_GPL(nf_conntrack_lock); 51 52/* nf_conntrack_standalone needs this */ 53atomic_t nf_conntrack_count = ATOMIC_INIT(0); 54EXPORT_SYMBOL_GPL(nf_conntrack_count); 55 56unsigned int nf_conntrack_htable_size __read_mostly; 57EXPORT_SYMBOL_GPL(nf_conntrack_htable_size); 58 59int nf_conntrack_max __read_mostly; 60EXPORT_SYMBOL_GPL(nf_conntrack_max); 61 62struct hlist_head *nf_conntrack_hash __read_mostly; 63EXPORT_SYMBOL_GPL(nf_conntrack_hash); 64 65struct nf_conn nf_conntrack_untracked __read_mostly; 66EXPORT_SYMBOL_GPL(nf_conntrack_untracked); 67 68unsigned int nf_ct_log_invalid __read_mostly; 69HLIST_HEAD(unconfirmed); 70static int nf_conntrack_vmalloc __read_mostly; 71static struct kmem_cache *nf_conntrack_cachep __read_mostly; 72static unsigned int nf_conntrack_next_id; 73 74DEFINE_PER_CPU(struct ip_conntrack_stat, nf_conntrack_stat); 75EXPORT_PER_CPU_SYMBOL(nf_conntrack_stat); 76 77static int nf_conntrack_hash_rnd_initted; 78static unsigned int nf_conntrack_hash_rnd; 79 80static u_int32_t __hash_conntrack(const struct nf_conntrack_tuple *tuple, 81 unsigned int size, unsigned int rnd) 82{ 83 unsigned int a, b; 84 85 a = jhash2(tuple->src.u3.all, ARRAY_SIZE(tuple->src.u3.all), 86 (tuple->src.l3num << 16) | tuple->dst.protonum); 87 b = jhash2(tuple->dst.u3.all, ARRAY_SIZE(tuple->dst.u3.all), 88 (tuple->src.u.all << 16) | tuple->dst.u.all); 89 90 return jhash_2words(a, b, rnd) % size; 91} 92 93static inline u_int32_t hash_conntrack(const struct nf_conntrack_tuple *tuple) 94{ 95 return __hash_conntrack(tuple, nf_conntrack_htable_size, 96 nf_conntrack_hash_rnd); 97} 98 99int 100nf_ct_get_tuple(const struct sk_buff *skb, 101 unsigned int nhoff, 102 unsigned int dataoff, 103 u_int16_t l3num, 104 u_int8_t protonum, 105 struct nf_conntrack_tuple *tuple, 106 const struct nf_conntrack_l3proto *l3proto, 107 const struct nf_conntrack_l4proto *l4proto) 108{ 109 NF_CT_TUPLE_U_BLANK(tuple); 110 111 tuple->src.l3num = l3num; 112 if (l3proto->pkt_to_tuple(skb, nhoff, tuple) == 0) 113 return 0; 114 115 tuple->dst.protonum = protonum; 116 tuple->dst.dir = IP_CT_DIR_ORIGINAL; 117 118 return l4proto->pkt_to_tuple(skb, dataoff, tuple); 119} 120EXPORT_SYMBOL_GPL(nf_ct_get_tuple); 121 122int 123nf_ct_invert_tuple(struct nf_conntrack_tuple *inverse, 124 const struct nf_conntrack_tuple *orig, 125 const struct nf_conntrack_l3proto *l3proto, 126 const struct nf_conntrack_l4proto *l4proto) 127{ 128 NF_CT_TUPLE_U_BLANK(inverse); 129 130 inverse->src.l3num = orig->src.l3num; 131 if (l3proto->invert_tuple(inverse, orig) == 0) 132 return 0; 133 134 inverse->dst.dir = !orig->dst.dir; 135 136 inverse->dst.protonum = orig->dst.protonum; 137 return l4proto->invert_tuple(inverse, orig); 138} 139EXPORT_SYMBOL_GPL(nf_ct_invert_tuple); 140 141static void 142clean_from_lists(struct nf_conn *ct) 143{ 144 DEBUGP("clean_from_lists(%p)\n", ct); 145 hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode); 146 hlist_del(&ct->tuplehash[IP_CT_DIR_REPLY].hnode); 147 148 /* Destroy all pending expectations */ 149 nf_ct_remove_expectations(ct); 150} 151 152static void 153destroy_conntrack(struct nf_conntrack *nfct) 154{ 155 struct nf_conn *ct = (struct nf_conn *)nfct; 156 struct nf_conntrack_l4proto *l4proto; 157 158 DEBUGP("destroy_conntrack(%p)\n", ct); 159 NF_CT_ASSERT(atomic_read(&nfct->use) == 0); 160 NF_CT_ASSERT(!timer_pending(&ct->timeout)); 161 162 nf_conntrack_event(IPCT_DESTROY, ct); 163 set_bit(IPS_DYING_BIT, &ct->status); 164 165 /* To make sure we don't get any weird locking issues here: 166 * destroy_conntrack() MUST NOT be called with a write lock 167 * to nf_conntrack_lock!!! -HW */ 168 rcu_read_lock(); 169 l4proto = __nf_ct_l4proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.l3num, 170 ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum); 171 if (l4proto && l4proto->destroy) 172 l4proto->destroy(ct); 173 174 nf_ct_ext_destroy(ct); 175 176 rcu_read_unlock(); 177 178 write_lock_bh(&nf_conntrack_lock); 179 /* Expectations will have been removed in clean_from_lists, 180 * except TFTP can create an expectation on the first packet, 181 * before connection is in the list, so we need to clean here, 182 * too. */ 183 nf_ct_remove_expectations(ct); 184 185 /* We overload first tuple to link into unconfirmed list. */ 186 if (!nf_ct_is_confirmed(ct)) { 187 BUG_ON(hlist_unhashed(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode)); 188 hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode); 189 } 190 191 NF_CT_STAT_INC(delete); 192 write_unlock_bh(&nf_conntrack_lock); 193 194 if (ct->master) 195 nf_ct_put(ct->master); 196 197 DEBUGP("destroy_conntrack: returning ct=%p to slab\n", ct); 198 nf_conntrack_free(ct); 199} 200 201static void death_by_timeout(unsigned long ul_conntrack) 202{ 203 struct nf_conn *ct = (void *)ul_conntrack; 204 struct nf_conn_help *help = nfct_help(ct); 205 struct nf_conntrack_helper *helper; 206 207 if (help) { 208 rcu_read_lock(); 209 helper = rcu_dereference(help->helper); 210 if (helper && helper->destroy) 211 helper->destroy(ct); 212 rcu_read_unlock(); 213 } 214 215 write_lock_bh(&nf_conntrack_lock); 216 /* Inside lock so preempt is disabled on module removal path. 217 * Otherwise we can get spurious warnings. */ 218 NF_CT_STAT_INC(delete_list); 219 clean_from_lists(ct); 220 write_unlock_bh(&nf_conntrack_lock); 221 nf_ct_put(ct); 222} 223 224struct nf_conntrack_tuple_hash * 225__nf_conntrack_find(const struct nf_conntrack_tuple *tuple, 226 const struct nf_conn *ignored_conntrack) 227{ 228 struct nf_conntrack_tuple_hash *h; 229 struct hlist_node *n; 230 unsigned int hash = hash_conntrack(tuple); 231 232 hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode) { 233 if (nf_ct_tuplehash_to_ctrack(h) != ignored_conntrack && 234 nf_ct_tuple_equal(tuple, &h->tuple)) { 235 NF_CT_STAT_INC(found); 236 return h; 237 } 238 NF_CT_STAT_INC(searched); 239 } 240 241 return NULL; 242} 243EXPORT_SYMBOL_GPL(__nf_conntrack_find); 244 245/* Find a connection corresponding to a tuple. */ 246struct nf_conntrack_tuple_hash * 247nf_conntrack_find_get(const struct nf_conntrack_tuple *tuple) 248{ 249 struct nf_conntrack_tuple_hash *h; 250 251 read_lock_bh(&nf_conntrack_lock); 252 h = __nf_conntrack_find(tuple, NULL); 253 if (h) 254 atomic_inc(&nf_ct_tuplehash_to_ctrack(h)->ct_general.use); 255 read_unlock_bh(&nf_conntrack_lock); 256 257 return h; 258} 259EXPORT_SYMBOL_GPL(nf_conntrack_find_get); 260 261static void __nf_conntrack_hash_insert(struct nf_conn *ct, 262 unsigned int hash, 263 unsigned int repl_hash) 264{ 265 ct->id = ++nf_conntrack_next_id; 266 hlist_add_head(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode, 267 &nf_conntrack_hash[hash]); 268 hlist_add_head(&ct->tuplehash[IP_CT_DIR_REPLY].hnode, 269 &nf_conntrack_hash[repl_hash]); 270} 271 272void nf_conntrack_hash_insert(struct nf_conn *ct) 273{ 274 unsigned int hash, repl_hash; 275 276 hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); 277 repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); 278 279 write_lock_bh(&nf_conntrack_lock); 280 __nf_conntrack_hash_insert(ct, hash, repl_hash); 281 write_unlock_bh(&nf_conntrack_lock); 282} 283EXPORT_SYMBOL_GPL(nf_conntrack_hash_insert); 284 285/* Confirm a connection given skb; places it in hash table */ 286int 287__nf_conntrack_confirm(struct sk_buff **pskb) 288{ 289 unsigned int hash, repl_hash; 290 struct nf_conntrack_tuple_hash *h; 291 struct nf_conn *ct; 292 struct nf_conn_help *help; 293 struct hlist_node *n; 294 enum ip_conntrack_info ctinfo; 295 296 ct = nf_ct_get(*pskb, &ctinfo); 297 298 /* ipt_REJECT uses nf_conntrack_attach to attach related 299 ICMP/TCP RST packets in other direction. Actual packet 300 which created connection will be IP_CT_NEW or for an 301 expected connection, IP_CT_RELATED. */ 302 if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) 303 return NF_ACCEPT; 304 305 hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); 306 repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); 307 308 /* We're not in hash table, and we refuse to set up related 309 connections for unconfirmed conns. But packet copies and 310 REJECT will give spurious warnings here. */ 311 /* NF_CT_ASSERT(atomic_read(&ct->ct_general.use) == 1); */ 312 313 /* No external references means noone else could have 314 confirmed us. */ 315 NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); 316 DEBUGP("Confirming conntrack %p\n", ct); 317 318 write_lock_bh(&nf_conntrack_lock); 319 320 /* See if there's one in the list already, including reverse: 321 NAT could have grabbed it without realizing, since we're 322 not in the hash. If there is, we lost race. */ 323 hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode) 324 if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, 325 &h->tuple)) 326 goto out; 327 hlist_for_each_entry(h, n, &nf_conntrack_hash[repl_hash], hnode) 328 if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_REPLY].tuple, 329 &h->tuple)) 330 goto out; 331 332 /* Remove from unconfirmed list */ 333 hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode); 334 335 __nf_conntrack_hash_insert(ct, hash, repl_hash); 336 /* Timer relative to confirmation time, not original 337 setting time, otherwise we'd get timer wrap in 338 weird delay cases. */ 339 ct->timeout.expires += jiffies; 340 add_timer(&ct->timeout); 341 atomic_inc(&ct->ct_general.use); 342 set_bit(IPS_CONFIRMED_BIT, &ct->status); 343 NF_CT_STAT_INC(insert); 344 write_unlock_bh(&nf_conntrack_lock); 345 help = nfct_help(ct); 346 if (help && help->helper) 347 nf_conntrack_event_cache(IPCT_HELPER, *pskb); 348#ifdef CONFIG_NF_NAT_NEEDED 349 if (test_bit(IPS_SRC_NAT_DONE_BIT, &ct->status) || 350 test_bit(IPS_DST_NAT_DONE_BIT, &ct->status)) 351 nf_conntrack_event_cache(IPCT_NATINFO, *pskb); 352#endif 353 nf_conntrack_event_cache(master_ct(ct) ? 354 IPCT_RELATED : IPCT_NEW, *pskb); 355 return NF_ACCEPT; 356 357out: 358 NF_CT_STAT_INC(insert_failed); 359 write_unlock_bh(&nf_conntrack_lock); 360 return NF_DROP; 361} 362EXPORT_SYMBOL_GPL(__nf_conntrack_confirm); 363 364/* Returns true if a connection correspondings to the tuple (required 365 for NAT). */ 366int 367nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple, 368 const struct nf_conn *ignored_conntrack) 369{ 370 struct nf_conntrack_tuple_hash *h; 371 372 read_lock_bh(&nf_conntrack_lock); 373 h = __nf_conntrack_find(tuple, ignored_conntrack); 374 read_unlock_bh(&nf_conntrack_lock); 375 376 return h != NULL; 377} 378EXPORT_SYMBOL_GPL(nf_conntrack_tuple_taken); 379 380/* There's a small race here where we may free a just-assured 381 connection. Too bad: we're in trouble anyway. */ 382static int early_drop(struct hlist_head *chain) 383{ 384 /* Use oldest entry, which is roughly LRU */ 385 struct nf_conntrack_tuple_hash *h; 386 struct nf_conn *ct = NULL, *tmp; 387 struct hlist_node *n; 388 int dropped = 0; 389 390 read_lock_bh(&nf_conntrack_lock); 391 hlist_for_each_entry(h, n, chain, hnode) { 392 tmp = nf_ct_tuplehash_to_ctrack(h); 393 if (!test_bit(IPS_ASSURED_BIT, &tmp->status)) 394 ct = tmp; 395 } 396 if (ct) 397 atomic_inc(&ct->ct_general.use); 398 read_unlock_bh(&nf_conntrack_lock); 399 400 if (!ct) 401 return dropped; 402 403 if (del_timer(&ct->timeout)) { 404 death_by_timeout((unsigned long)ct); 405 dropped = 1; 406 NF_CT_STAT_INC_ATOMIC(early_drop); 407 } 408 nf_ct_put(ct); 409 return dropped; 410} 411 412struct nf_conn *nf_conntrack_alloc(const struct nf_conntrack_tuple *orig, 413 const struct nf_conntrack_tuple *repl) 414{ 415 struct nf_conn *conntrack = NULL; 416 417 if (unlikely(!nf_conntrack_hash_rnd_initted)) { 418 get_random_bytes(&nf_conntrack_hash_rnd, 4); 419 nf_conntrack_hash_rnd_initted = 1; 420 } 421 422 /* We don't want any race condition at early drop stage */ 423 atomic_inc(&nf_conntrack_count); 424 425 if (nf_conntrack_max 426 && atomic_read(&nf_conntrack_count) > nf_conntrack_max) { 427 unsigned int hash = hash_conntrack(orig); 428 /* Try dropping from this hash chain. */ 429 if (!early_drop(&nf_conntrack_hash[hash])) { 430 atomic_dec(&nf_conntrack_count); 431 if (net_ratelimit()) 432 printk(KERN_WARNING 433 "nf_conntrack: table full, dropping" 434 " packet.\n"); 435 return ERR_PTR(-ENOMEM); 436 } 437 } 438 439 conntrack = kmem_cache_zalloc(nf_conntrack_cachep, GFP_ATOMIC); 440 if (conntrack == NULL) { 441 DEBUGP("nf_conntrack_alloc: Can't alloc conntrack.\n"); 442 atomic_dec(&nf_conntrack_count); 443 return ERR_PTR(-ENOMEM); 444 } 445 446 atomic_set(&conntrack->ct_general.use, 1); 447 conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *orig; 448 conntrack->tuplehash[IP_CT_DIR_REPLY].tuple = *repl; 449 /* Don't set timer yet: wait for confirmation */ 450 setup_timer(&conntrack->timeout, death_by_timeout, 451 (unsigned long)conntrack); 452 453 return conntrack; 454} 455EXPORT_SYMBOL_GPL(nf_conntrack_alloc); 456 457void nf_conntrack_free(struct nf_conn *conntrack) 458{ 459 nf_ct_ext_free(conntrack); 460 kmem_cache_free(nf_conntrack_cachep, conntrack); 461 atomic_dec(&nf_conntrack_count); 462} 463EXPORT_SYMBOL_GPL(nf_conntrack_free); 464 465/* Allocate a new conntrack: we return -ENOMEM if classification 466 failed due to stress. Otherwise it really is unclassifiable. */ 467static struct nf_conntrack_tuple_hash * 468init_conntrack(const struct nf_conntrack_tuple *tuple, 469 struct nf_conntrack_l3proto *l3proto, 470 struct nf_conntrack_l4proto *l4proto, 471 struct sk_buff *skb, 472 unsigned int dataoff) 473{ 474 struct nf_conn *conntrack; 475 struct nf_conn_help *help; 476 struct nf_conntrack_tuple repl_tuple; 477 struct nf_conntrack_expect *exp; 478 479 if (!nf_ct_invert_tuple(&repl_tuple, tuple, l3proto, l4proto)) { 480 DEBUGP("Can't invert tuple.\n"); 481 return NULL; 482 } 483 484 conntrack = nf_conntrack_alloc(tuple, &repl_tuple); 485 if (conntrack == NULL || IS_ERR(conntrack)) { 486 DEBUGP("Can't allocate conntrack.\n"); 487 return (struct nf_conntrack_tuple_hash *)conntrack; 488 } 489 490 if (!l4proto->new(conntrack, skb, dataoff)) { 491 nf_conntrack_free(conntrack); 492 DEBUGP("init conntrack: can't track with proto module\n"); 493 return NULL; 494 } 495 496 write_lock_bh(&nf_conntrack_lock); 497 exp = nf_ct_find_expectation(tuple); 498 if (exp) { 499 DEBUGP("conntrack: expectation arrives ct=%p exp=%p\n", 500 conntrack, exp); 501 /* Welcome, Mr. Bond. We've been expecting you... */ 502 __set_bit(IPS_EXPECTED_BIT, &conntrack->status); 503 conntrack->master = exp->master; 504 if (exp->helper) { 505 help = nf_ct_ext_add(conntrack, NF_CT_EXT_HELPER, 506 GFP_ATOMIC); 507 if (help) 508 rcu_assign_pointer(help->helper, exp->helper); 509 else 510 DEBUGP("failed to add helper extension area"); 511 } 512 513#ifdef CONFIG_NF_CONNTRACK_MARK 514 conntrack->mark = exp->master->mark; 515#endif 516#ifdef CONFIG_NF_CONNTRACK_SECMARK 517 conntrack->secmark = exp->master->secmark; 518#endif 519 nf_conntrack_get(&conntrack->master->ct_general); 520 NF_CT_STAT_INC(expect_new); 521 } else { 522 struct nf_conntrack_helper *helper; 523 524 helper = __nf_ct_helper_find(&repl_tuple); 525 if (helper) { 526 help = nf_ct_ext_add(conntrack, NF_CT_EXT_HELPER, 527 GFP_ATOMIC); 528 if (help) 529 /* not in hash table yet, so not strictly 530 necessary */ 531 rcu_assign_pointer(help->helper, helper); 532 else 533 DEBUGP("failed to add helper extension area"); 534 } 535 NF_CT_STAT_INC(new); 536 } 537 538 /* Overload tuple linked list to put us in unconfirmed list. */ 539 hlist_add_head(&conntrack->tuplehash[IP_CT_DIR_ORIGINAL].hnode, 540 &unconfirmed); 541 542 write_unlock_bh(&nf_conntrack_lock); 543 544 if (exp) { 545 if (exp->expectfn) 546 exp->expectfn(conntrack, exp); 547 nf_ct_expect_put(exp); 548 } 549 550 return &conntrack->tuplehash[IP_CT_DIR_ORIGINAL]; 551} 552 553/* On success, returns conntrack ptr, sets skb->nfct and ctinfo */ 554static inline struct nf_conn * 555resolve_normal_ct(struct sk_buff *skb, 556 unsigned int dataoff, 557 u_int16_t l3num, 558 u_int8_t protonum, 559 struct nf_conntrack_l3proto *l3proto, 560 struct nf_conntrack_l4proto *l4proto, 561 int *set_reply, 562 enum ip_conntrack_info *ctinfo) 563{ 564 struct nf_conntrack_tuple tuple; 565 struct nf_conntrack_tuple_hash *h; 566 struct nf_conn *ct; 567 568 if (!nf_ct_get_tuple(skb, skb_network_offset(skb), 569 dataoff, l3num, protonum, &tuple, l3proto, 570 l4proto)) { 571 DEBUGP("resolve_normal_ct: Can't get tuple\n"); 572 return NULL; 573 } 574 575 /* look for tuple match */ 576 h = nf_conntrack_find_get(&tuple); 577 if (!h) { 578 h = init_conntrack(&tuple, l3proto, l4proto, skb, dataoff); 579 if (!h) 580 return NULL; 581 if (IS_ERR(h)) 582 return (void *)h; 583 } 584 ct = nf_ct_tuplehash_to_ctrack(h); 585 586 /* It exists; we have (non-exclusive) reference. */ 587 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) { 588 *ctinfo = IP_CT_ESTABLISHED + IP_CT_IS_REPLY; 589 /* Please set reply bit if this packet OK */ 590 *set_reply = 1; 591 } else { 592 /* Once we've had two way comms, always ESTABLISHED. */ 593 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { 594 DEBUGP("nf_conntrack_in: normal packet for %p\n", ct); 595 *ctinfo = IP_CT_ESTABLISHED; 596 } else if (test_bit(IPS_EXPECTED_BIT, &ct->status)) { 597 DEBUGP("nf_conntrack_in: related packet for %p\n", ct); 598 *ctinfo = IP_CT_RELATED; 599 } else { 600 DEBUGP("nf_conntrack_in: new packet for %p\n", ct); 601 *ctinfo = IP_CT_NEW; 602 } 603 *set_reply = 0; 604 } 605 skb->nfct = &ct->ct_general; 606 skb->nfctinfo = *ctinfo; 607 return ct; 608} 609 610unsigned int 611nf_conntrack_in(int pf, unsigned int hooknum, struct sk_buff **pskb) 612{ 613 struct nf_conn *ct; 614 enum ip_conntrack_info ctinfo; 615 struct nf_conntrack_l3proto *l3proto; 616 struct nf_conntrack_l4proto *l4proto; 617 unsigned int dataoff; 618 u_int8_t protonum; 619 int set_reply = 0; 620 int ret; 621 622 /* Previously seen (loopback or untracked)? Ignore. */ 623 if ((*pskb)->nfct) { 624 NF_CT_STAT_INC_ATOMIC(ignore); 625 return NF_ACCEPT; 626 } 627 628 /* rcu_read_lock()ed by nf_hook_slow */ 629 l3proto = __nf_ct_l3proto_find((u_int16_t)pf); 630 631 if ((ret = l3proto->prepare(pskb, hooknum, &dataoff, &protonum)) <= 0) { 632 DEBUGP("not prepared to track yet or error occured\n"); 633 return -ret; 634 } 635 636 l4proto = __nf_ct_l4proto_find((u_int16_t)pf, protonum); 637 638 /* It may be an special packet, error, unclean... 639 * inverse of the return code tells to the netfilter 640 * core what to do with the packet. */ 641 if (l4proto->error != NULL && 642 (ret = l4proto->error(*pskb, dataoff, &ctinfo, pf, hooknum)) <= 0) { 643 NF_CT_STAT_INC_ATOMIC(error); 644 NF_CT_STAT_INC_ATOMIC(invalid); 645 return -ret; 646 } 647 648 ct = resolve_normal_ct(*pskb, dataoff, pf, protonum, l3proto, l4proto, 649 &set_reply, &ctinfo); 650 if (!ct) { 651 /* Not valid part of a connection */ 652 NF_CT_STAT_INC_ATOMIC(invalid); 653 return NF_ACCEPT; 654 } 655 656 if (IS_ERR(ct)) { 657 /* Too stressed to deal. */ 658 NF_CT_STAT_INC_ATOMIC(drop); 659 return NF_DROP; 660 } 661 662 NF_CT_ASSERT((*pskb)->nfct); 663 664 ret = l4proto->packet(ct, *pskb, dataoff, ctinfo, pf, hooknum); 665 if (ret < 0) { 666 /* Invalid: inverse of the return code tells 667 * the netfilter core what to do */ 668 DEBUGP("nf_conntrack_in: Can't track with proto module\n"); 669 nf_conntrack_put((*pskb)->nfct); 670 (*pskb)->nfct = NULL; 671 NF_CT_STAT_INC_ATOMIC(invalid); 672 return -ret; 673 } 674 675 if (set_reply && !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status)) 676 nf_conntrack_event_cache(IPCT_STATUS, *pskb); 677 678 return ret; 679} 680EXPORT_SYMBOL_GPL(nf_conntrack_in); 681 682int nf_ct_invert_tuplepr(struct nf_conntrack_tuple *inverse, 683 const struct nf_conntrack_tuple *orig) 684{ 685 int ret; 686 687 rcu_read_lock(); 688 ret = nf_ct_invert_tuple(inverse, orig, 689 __nf_ct_l3proto_find(orig->src.l3num), 690 __nf_ct_l4proto_find(orig->src.l3num, 691 orig->dst.protonum)); 692 rcu_read_unlock(); 693 return ret; 694} 695EXPORT_SYMBOL_GPL(nf_ct_invert_tuplepr); 696 697/* Alter reply tuple (maybe alter helper). This is for NAT, and is 698 implicitly racy: see __nf_conntrack_confirm */ 699void nf_conntrack_alter_reply(struct nf_conn *ct, 700 const struct nf_conntrack_tuple *newreply) 701{ 702 struct nf_conn_help *help = nfct_help(ct); 703 struct nf_conntrack_helper *helper; 704 705 write_lock_bh(&nf_conntrack_lock); 706 /* Should be unconfirmed, so not in hash table yet */ 707 NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); 708 709 DEBUGP("Altering reply tuple of %p to ", ct); 710 NF_CT_DUMP_TUPLE(newreply); 711 712 ct->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply; 713 if (ct->master || (help && help->expecting != 0)) 714 goto out; 715 716 helper = __nf_ct_helper_find(newreply); 717 if (helper == NULL) { 718 if (help) 719 rcu_assign_pointer(help->helper, NULL); 720 goto out; 721 } 722 723 if (help == NULL) { 724 help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, GFP_ATOMIC); 725 if (help == NULL) { 726 DEBUGP("failed to add helper extension area"); 727 goto out; 728 } 729 } else { 730 memset(&help->help, 0, sizeof(help->help)); 731 } 732 733 rcu_assign_pointer(help->helper, helper); 734out: 735 write_unlock_bh(&nf_conntrack_lock); 736} 737EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply); 738 739/* Refresh conntrack for this many jiffies and do accounting if do_acct is 1 */ 740void __nf_ct_refresh_acct(struct nf_conn *ct, 741 enum ip_conntrack_info ctinfo, 742 const struct sk_buff *skb, 743 unsigned long extra_jiffies, 744 int do_acct) 745{ 746 int event = 0; 747 748 NF_CT_ASSERT(ct->timeout.data == (unsigned long)ct); 749 NF_CT_ASSERT(skb); 750 751 write_lock_bh(&nf_conntrack_lock); 752 753 /* Only update if this is not a fixed timeout */ 754 if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status)) { 755 write_unlock_bh(&nf_conntrack_lock); 756 return; 757 } 758 759 /* If not in hash table, timer will not be active yet */ 760 if (!nf_ct_is_confirmed(ct)) { 761 ct->timeout.expires = extra_jiffies; 762 event = IPCT_REFRESH; 763 } else { 764 unsigned long newtime = jiffies + extra_jiffies; 765 766 /* Only update the timeout if the new timeout is at least 767 HZ jiffies from the old timeout. Need del_timer for race 768 avoidance (may already be dying). */ 769 if (newtime - ct->timeout.expires >= HZ 770 && del_timer(&ct->timeout)) { 771 ct->timeout.expires = newtime; 772 add_timer(&ct->timeout); 773 event = IPCT_REFRESH; 774 } 775 } 776 777#ifdef CONFIG_NF_CT_ACCT 778 if (do_acct) { 779 ct->counters[CTINFO2DIR(ctinfo)].packets++; 780 ct->counters[CTINFO2DIR(ctinfo)].bytes += 781 skb->len - skb_network_offset(skb); 782 783 if ((ct->counters[CTINFO2DIR(ctinfo)].packets & 0x80000000) 784 || (ct->counters[CTINFO2DIR(ctinfo)].bytes & 0x80000000)) 785 event |= IPCT_COUNTER_FILLING; 786 } 787#endif 788 789 write_unlock_bh(&nf_conntrack_lock); 790 791 /* must be unlocked when calling event cache */ 792 if (event) 793 nf_conntrack_event_cache(event, skb); 794} 795EXPORT_SYMBOL_GPL(__nf_ct_refresh_acct); 796 797#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE) 798 799#include <linux/netfilter/nfnetlink.h> 800#include <linux/netfilter/nfnetlink_conntrack.h> 801#include <linux/mutex.h> 802 803 804/* Generic function for tcp/udp/sctp/dccp and alike. This needs to be 805 * in ip_conntrack_core, since we don't want the protocols to autoload 806 * or depend on ctnetlink */ 807int nf_ct_port_tuple_to_nfattr(struct sk_buff *skb, 808 const struct nf_conntrack_tuple *tuple) 809{ 810 NFA_PUT(skb, CTA_PROTO_SRC_PORT, sizeof(u_int16_t), 811 &tuple->src.u.tcp.port); 812 NFA_PUT(skb, CTA_PROTO_DST_PORT, sizeof(u_int16_t), 813 &tuple->dst.u.tcp.port); 814 return 0; 815 816nfattr_failure: 817 return -1; 818} 819EXPORT_SYMBOL_GPL(nf_ct_port_tuple_to_nfattr); 820 821static const size_t cta_min_proto[CTA_PROTO_MAX] = { 822 [CTA_PROTO_SRC_PORT-1] = sizeof(u_int16_t), 823 [CTA_PROTO_DST_PORT-1] = sizeof(u_int16_t) 824}; 825 826int nf_ct_port_nfattr_to_tuple(struct nfattr *tb[], 827 struct nf_conntrack_tuple *t) 828{ 829 if (!tb[CTA_PROTO_SRC_PORT-1] || !tb[CTA_PROTO_DST_PORT-1]) 830 return -EINVAL; 831 832 if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto)) 833 return -EINVAL; 834 835 t->src.u.tcp.port = *(__be16 *)NFA_DATA(tb[CTA_PROTO_SRC_PORT-1]); 836 t->dst.u.tcp.port = *(__be16 *)NFA_DATA(tb[CTA_PROTO_DST_PORT-1]); 837 838 return 0; 839} 840EXPORT_SYMBOL_GPL(nf_ct_port_nfattr_to_tuple); 841#endif 842 843/* Used by ipt_REJECT and ip6t_REJECT. */ 844void __nf_conntrack_attach(struct sk_buff *nskb, struct sk_buff *skb) 845{ 846 struct nf_conn *ct; 847 enum ip_conntrack_info ctinfo; 848 849 /* This ICMP is in reverse direction to the packet which caused it */ 850 ct = nf_ct_get(skb, &ctinfo); 851 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) 852 ctinfo = IP_CT_RELATED + IP_CT_IS_REPLY; 853 else 854 ctinfo = IP_CT_RELATED; 855 856 /* Attach to new skbuff, and increment count */ 857 nskb->nfct = &ct->ct_general; 858 nskb->nfctinfo = ctinfo; 859 nf_conntrack_get(nskb->nfct); 860} 861EXPORT_SYMBOL_GPL(__nf_conntrack_attach); 862 863static inline int 864do_iter(const struct nf_conntrack_tuple_hash *i, 865 int (*iter)(struct nf_conn *i, void *data), 866 void *data) 867{ 868 return iter(nf_ct_tuplehash_to_ctrack(i), data); 869} 870 871/* Bring out ya dead! */ 872static struct nf_conn * 873get_next_corpse(int (*iter)(struct nf_conn *i, void *data), 874 void *data, unsigned int *bucket) 875{ 876 struct nf_conntrack_tuple_hash *h; 877 struct nf_conn *ct; 878 struct hlist_node *n; 879 880 write_lock_bh(&nf_conntrack_lock); 881 for (; *bucket < nf_conntrack_htable_size; (*bucket)++) { 882 hlist_for_each_entry(h, n, &nf_conntrack_hash[*bucket], hnode) { 883 ct = nf_ct_tuplehash_to_ctrack(h); 884 if (iter(ct, data)) 885 goto found; 886 } 887 } 888 hlist_for_each_entry(h, n, &unconfirmed, hnode) { 889 ct = nf_ct_tuplehash_to_ctrack(h); 890 if (iter(ct, data)) 891 set_bit(IPS_DYING_BIT, &ct->status); 892 } 893 write_unlock_bh(&nf_conntrack_lock); 894 return NULL; 895found: 896 atomic_inc(&ct->ct_general.use); 897 write_unlock_bh(&nf_conntrack_lock); 898 return ct; 899} 900 901void 902nf_ct_iterate_cleanup(int (*iter)(struct nf_conn *i, void *data), void *data) 903{ 904 struct nf_conn *ct; 905 unsigned int bucket = 0; 906 907 while ((ct = get_next_corpse(iter, data, &bucket)) != NULL) { 908 /* Time to push up daises... */ 909 if (del_timer(&ct->timeout)) 910 death_by_timeout((unsigned long)ct); 911 /* ... else the timer will get him soon. */ 912 913 nf_ct_put(ct); 914 } 915} 916EXPORT_SYMBOL_GPL(nf_ct_iterate_cleanup); 917 918static int kill_all(struct nf_conn *i, void *data) 919{ 920 return 1; 921} 922 923void nf_ct_free_hashtable(struct hlist_head *hash, int vmalloced, int size) 924{ 925 if (vmalloced) 926 vfree(hash); 927 else 928 free_pages((unsigned long)hash, 929 get_order(sizeof(struct hlist_head) * size)); 930} 931EXPORT_SYMBOL_GPL(nf_ct_free_hashtable); 932 933void nf_conntrack_flush(void) 934{ 935 nf_ct_iterate_cleanup(kill_all, NULL); 936} 937EXPORT_SYMBOL_GPL(nf_conntrack_flush); 938 939/* Mishearing the voices in his head, our hero wonders how he's 940 supposed to kill the mall. */ 941void nf_conntrack_cleanup(void) 942{ 943 rcu_assign_pointer(ip_ct_attach, NULL); 944 945 /* This makes sure all current packets have passed through 946 netfilter framework. Roll on, two-stage module 947 delete... */ 948 synchronize_net(); 949 950 nf_ct_event_cache_flush(); 951 i_see_dead_people: 952 nf_conntrack_flush(); 953 if (atomic_read(&nf_conntrack_count) != 0) { 954 schedule(); 955 goto i_see_dead_people; 956 } 957 /* wait until all references to nf_conntrack_untracked are dropped */ 958 while (atomic_read(&nf_conntrack_untracked.ct_general.use) > 1) 959 schedule(); 960 961 rcu_assign_pointer(nf_ct_destroy, NULL); 962 963 kmem_cache_destroy(nf_conntrack_cachep); 964 kmem_cache_destroy(nf_ct_expect_cachep); 965 nf_ct_free_hashtable(nf_conntrack_hash, nf_conntrack_vmalloc, 966 nf_conntrack_htable_size); 967 968 nf_conntrack_proto_fini(); 969 nf_conntrack_helper_fini(); 970} 971 972struct hlist_head *nf_ct_alloc_hashtable(int *sizep, int *vmalloced) 973{ 974 struct hlist_head *hash; 975 unsigned int size, i; 976 977 *vmalloced = 0; 978 979 size = *sizep = roundup(*sizep, PAGE_SIZE / sizeof(struct hlist_head)); 980 hash = (void*)__get_free_pages(GFP_KERNEL, 981 get_order(sizeof(struct hlist_head) 982 * size)); 983 if (!hash) { 984 *vmalloced = 1; 985 printk(KERN_WARNING "nf_conntrack: falling back to vmalloc.\n"); 986 hash = vmalloc(sizeof(struct hlist_head) * size); 987 } 988 989 if (hash) 990 for (i = 0; i < size; i++) 991 INIT_HLIST_HEAD(&hash[i]); 992 993 return hash; 994} 995EXPORT_SYMBOL_GPL(nf_ct_alloc_hashtable); 996 997int set_hashsize(const char *val, struct kernel_param *kp) 998{ 999 int i, bucket, hashsize, vmalloced; 1000 int old_vmalloced, old_size; 1001 int rnd; 1002 struct hlist_head *hash, *old_hash; 1003 struct nf_conntrack_tuple_hash *h; 1004 1005 /* On boot, we can set this without any fancy locking. */ 1006 if (!nf_conntrack_htable_size) 1007 return param_set_uint(val, kp); 1008 1009 hashsize = simple_strtol(val, NULL, 0); 1010 if (!hashsize) 1011 return -EINVAL; 1012 1013 hash = nf_ct_alloc_hashtable(&hashsize, &vmalloced); 1014 if (!hash) 1015 return -ENOMEM; 1016 1017 /* We have to rehahs for the new table anyway, so we also can 1018 * use a newrandom seed */ 1019 get_random_bytes(&rnd, 4); 1020 1021 write_lock_bh(&nf_conntrack_lock); 1022 for (i = 0; i < nf_conntrack_htable_size; i++) { 1023 while (!hlist_empty(&nf_conntrack_hash[i])) { 1024 h = hlist_entry(nf_conntrack_hash[i].first, 1025 struct nf_conntrack_tuple_hash, hnode); 1026 hlist_del(&h->hnode); 1027 bucket = __hash_conntrack(&h->tuple, hashsize, rnd); 1028 hlist_add_head(&h->hnode, &hash[bucket]); 1029 } 1030 } 1031 old_size = nf_conntrack_htable_size; 1032 old_vmalloced = nf_conntrack_vmalloc; 1033 old_hash = nf_conntrack_hash; 1034 1035 nf_conntrack_htable_size = hashsize; 1036 nf_conntrack_vmalloc = vmalloced; 1037 nf_conntrack_hash = hash; 1038 nf_conntrack_hash_rnd = rnd; 1039 write_unlock_bh(&nf_conntrack_lock); 1040 1041 nf_ct_free_hashtable(old_hash, old_vmalloced, old_size); 1042 return 0; 1043} 1044 1045module_param_call(hashsize, set_hashsize, param_get_uint, 1046 &nf_conntrack_htable_size, 0600); 1047 1048int __init nf_conntrack_init(void) 1049{ 1050 int max_factor = 8; 1051 int ret; 1052 1053 /* Idea from tcp.c: use 1/16384 of memory. On i386: 32MB 1054 * machine has 512 buckets. >= 1GB machines have 16384 buckets. */ 1055 if (!nf_conntrack_htable_size) { 1056 nf_conntrack_htable_size 1057 = (((num_physpages << PAGE_SHIFT) / 16384) 1058 / sizeof(struct hlist_head)); 1059 if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE)) 1060 nf_conntrack_htable_size = 16384; 1061 if (nf_conntrack_htable_size < 32) 1062 nf_conntrack_htable_size = 32; 1063 1064 /* Use a max. factor of four by default to get the same max as 1065 * with the old struct list_heads. When a table size is given 1066 * we use the old value of 8 to avoid reducing the max. 1067 * entries. */ 1068 max_factor = 4; 1069 } 1070 nf_conntrack_hash = nf_ct_alloc_hashtable(&nf_conntrack_htable_size, 1071 &nf_conntrack_vmalloc); 1072 if (!nf_conntrack_hash) { 1073 printk(KERN_ERR "Unable to create nf_conntrack_hash\n"); 1074 goto err_out; 1075 } 1076 1077 nf_conntrack_max = max_factor * nf_conntrack_htable_size; 1078 1079 printk("nf_conntrack version %s (%u buckets, %d max)\n", 1080 NF_CONNTRACK_VERSION, nf_conntrack_htable_size, 1081 nf_conntrack_max); 1082 1083 nf_conntrack_cachep = kmem_cache_create("nf_conntrack", 1084 sizeof(struct nf_conn), 1085 0, 0, NULL, NULL); 1086 if (!nf_conntrack_cachep) { 1087 printk(KERN_ERR "Unable to create nf_conn slab cache\n"); 1088 goto err_free_hash; 1089 } 1090 1091 nf_ct_expect_cachep = kmem_cache_create("nf_conntrack_expect", 1092 sizeof(struct nf_conntrack_expect), 1093 0, 0, NULL, NULL); 1094 if (!nf_ct_expect_cachep) { 1095 printk(KERN_ERR "Unable to create nf_expect slab cache\n"); 1096 goto err_free_conntrack_slab; 1097 } 1098 1099 ret = nf_conntrack_proto_init(); 1100 if (ret < 0) 1101 goto out_free_expect_slab; 1102 1103 ret = nf_conntrack_helper_init(); 1104 if (ret < 0) 1105 goto out_fini_proto; 1106 1107 /* For use by REJECT target */ 1108 rcu_assign_pointer(ip_ct_attach, __nf_conntrack_attach); 1109 rcu_assign_pointer(nf_ct_destroy, destroy_conntrack); 1110 1111 /* Set up fake conntrack: 1112 - to never be deleted, not in any hashes */ 1113 atomic_set(&nf_conntrack_untracked.ct_general.use, 1); 1114 /* - and look it like as a confirmed connection */ 1115 set_bit(IPS_CONFIRMED_BIT, &nf_conntrack_untracked.status); 1116 1117 return ret; 1118 1119out_fini_proto: 1120 nf_conntrack_proto_fini(); 1121out_free_expect_slab: 1122 kmem_cache_destroy(nf_ct_expect_cachep); 1123err_free_conntrack_slab: 1124 kmem_cache_destroy(nf_conntrack_cachep); 1125err_free_hash: 1126 nf_ct_free_hashtable(nf_conntrack_hash, nf_conntrack_vmalloc, 1127 nf_conntrack_htable_size); 1128err_out: 1129 return -ENOMEM; 1130} 1131