1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * (C) 1999-2001 Paul `Rusty' Russell 4 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> 5 * (C) 2011 Patrick McHardy <kaber@trash.net> 6 */ 7 8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 9 10 #include <linux/module.h> 11 #include <linux/types.h> 12 #include <linux/timer.h> 13 #include <linux/skbuff.h> 14 #include <linux/gfp.h> 15 #include <net/xfrm.h> 16 #include <linux/siphash.h> 17 #include <linux/rtnetlink.h> 18 19 #include <net/netfilter/nf_conntrack_bpf.h> 20 #include <net/netfilter/nf_conntrack_core.h> 21 #include <net/netfilter/nf_conntrack_helper.h> 22 #include <net/netfilter/nf_conntrack_seqadj.h> 23 #include <net/netfilter/nf_conntrack_zones.h> 24 #include <net/netfilter/nf_nat.h> 25 #include <net/netfilter/nf_nat_helper.h> 26 #include <uapi/linux/netfilter/nf_nat.h> 27 28 #include "nf_internals.h" 29 30 #define NF_NAT_MAX_ATTEMPTS 128 31 #define NF_NAT_HARDER_THRESH (NF_NAT_MAX_ATTEMPTS / 4) 32 33 static spinlock_t nf_nat_locks[CONNTRACK_LOCKS]; 34 35 static DEFINE_MUTEX(nf_nat_proto_mutex); 36 static unsigned int nat_net_id __read_mostly; 37 38 static struct hlist_head *nf_nat_bysource __read_mostly; 39 static unsigned int nf_nat_htable_size __read_mostly; 40 static siphash_aligned_key_t nf_nat_hash_rnd; 41 42 struct nf_nat_lookup_hook_priv { 43 struct nf_hook_entries __rcu *entries; 44 45 struct rcu_head rcu_head; 46 }; 47 48 struct nf_nat_hooks_net { 49 struct nf_hook_ops *nat_hook_ops; 50 unsigned int users; 51 }; 52 53 struct nat_net { 54 struct nf_nat_hooks_net nat_proto_net[NFPROTO_NUMPROTO]; 55 }; 56 57 #ifdef CONFIG_XFRM 58 static void nf_nat_ipv4_decode_session(struct sk_buff *skb, 59 const struct nf_conn *ct, 60 enum ip_conntrack_dir dir, 61 unsigned long statusbit, 62 struct flowi *fl) 63 { 64 const struct nf_conntrack_tuple *t = &ct->tuplehash[dir].tuple; 65 struct flowi4 *fl4 = &fl->u.ip4; 66 67 if (ct->status & statusbit) { 68 fl4->daddr = t->dst.u3.ip; 69 if (t->dst.protonum == IPPROTO_TCP || 70 t->dst.protonum == IPPROTO_UDP || 71 t->dst.protonum == IPPROTO_UDPLITE || 72 t->dst.protonum == IPPROTO_DCCP || 73 t->dst.protonum == IPPROTO_SCTP) 74 fl4->fl4_dport = t->dst.u.all; 75 } 76 77 statusbit ^= IPS_NAT_MASK; 78 79 if (ct->status & statusbit) { 80 fl4->saddr = t->src.u3.ip; 81 if (t->dst.protonum == IPPROTO_TCP || 82 t->dst.protonum == IPPROTO_UDP || 83 t->dst.protonum == IPPROTO_UDPLITE || 84 t->dst.protonum == IPPROTO_DCCP || 85 t->dst.protonum == IPPROTO_SCTP) 86 fl4->fl4_sport = t->src.u.all; 87 } 88 } 89 90 static void nf_nat_ipv6_decode_session(struct sk_buff *skb, 91 const struct nf_conn *ct, 92 enum ip_conntrack_dir dir, 93 unsigned long statusbit, 94 struct flowi *fl) 95 { 96 #if IS_ENABLED(CONFIG_IPV6) 97 const struct nf_conntrack_tuple *t = &ct->tuplehash[dir].tuple; 98 struct flowi6 *fl6 = &fl->u.ip6; 99 100 if (ct->status & statusbit) { 101 fl6->daddr = t->dst.u3.in6; 102 if (t->dst.protonum == IPPROTO_TCP || 103 t->dst.protonum == IPPROTO_UDP || 104 t->dst.protonum == IPPROTO_UDPLITE || 105 t->dst.protonum == IPPROTO_DCCP || 106 t->dst.protonum == IPPROTO_SCTP) 107 fl6->fl6_dport = t->dst.u.all; 108 } 109 110 statusbit ^= IPS_NAT_MASK; 111 112 if (ct->status & statusbit) { 113 fl6->saddr = t->src.u3.in6; 114 if (t->dst.protonum == IPPROTO_TCP || 115 t->dst.protonum == IPPROTO_UDP || 116 t->dst.protonum == IPPROTO_UDPLITE || 117 t->dst.protonum == IPPROTO_DCCP || 118 t->dst.protonum == IPPROTO_SCTP) 119 fl6->fl6_sport = t->src.u.all; 120 } 121 #endif 122 } 123 124 static void __nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl) 125 { 126 const struct nf_conn *ct; 127 enum ip_conntrack_info ctinfo; 128 enum ip_conntrack_dir dir; 129 unsigned long statusbit; 130 u8 family; 131 132 ct = nf_ct_get(skb, &ctinfo); 133 if (ct == NULL) 134 return; 135 136 family = nf_ct_l3num(ct); 137 dir = CTINFO2DIR(ctinfo); 138 if (dir == IP_CT_DIR_ORIGINAL) 139 statusbit = IPS_DST_NAT; 140 else 141 statusbit = IPS_SRC_NAT; 142 143 switch (family) { 144 case NFPROTO_IPV4: 145 nf_nat_ipv4_decode_session(skb, ct, dir, statusbit, fl); 146 return; 147 case NFPROTO_IPV6: 148 nf_nat_ipv6_decode_session(skb, ct, dir, statusbit, fl); 149 return; 150 } 151 } 152 #endif /* CONFIG_XFRM */ 153 154 /* We keep an extra hash for each conntrack, for fast searching. */ 155 static unsigned int 156 hash_by_src(const struct net *net, 157 const struct nf_conntrack_zone *zone, 158 const struct nf_conntrack_tuple *tuple) 159 { 160 unsigned int hash; 161 struct { 162 struct nf_conntrack_man src; 163 u32 net_mix; 164 u32 protonum; 165 u32 zone; 166 } __aligned(SIPHASH_ALIGNMENT) combined; 167 168 get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd)); 169 170 memset(&combined, 0, sizeof(combined)); 171 172 /* Original src, to ensure we map it consistently if poss. */ 173 combined.src = tuple->src; 174 combined.net_mix = net_hash_mix(net); 175 combined.protonum = tuple->dst.protonum; 176 177 /* Zone ID can be used provided its valid for both directions */ 178 if (zone->dir == NF_CT_DEFAULT_ZONE_DIR) 179 combined.zone = zone->id; 180 181 hash = siphash(&combined, sizeof(combined), &nf_nat_hash_rnd); 182 183 return reciprocal_scale(hash, nf_nat_htable_size); 184 } 185 186 /* Is this tuple already taken? (not by us) */ 187 static int 188 nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple, 189 const struct nf_conn *ignored_conntrack) 190 { 191 /* Conntrack tracking doesn't keep track of outgoing tuples; only 192 * incoming ones. NAT means they don't have a fixed mapping, 193 * so we invert the tuple and look for the incoming reply. 194 * 195 * We could keep a separate hash if this proves too slow. 196 */ 197 struct nf_conntrack_tuple reply; 198 199 nf_ct_invert_tuple(&reply, tuple); 200 return nf_conntrack_tuple_taken(&reply, ignored_conntrack); 201 } 202 203 static bool nf_nat_may_kill(struct nf_conn *ct, unsigned long flags) 204 { 205 static const unsigned long flags_refuse = IPS_FIXED_TIMEOUT | 206 IPS_DYING; 207 static const unsigned long flags_needed = IPS_SRC_NAT; 208 enum tcp_conntrack old_state; 209 210 old_state = READ_ONCE(ct->proto.tcp.state); 211 if (old_state < TCP_CONNTRACK_TIME_WAIT) 212 return false; 213 214 if (flags & flags_refuse) 215 return false; 216 217 return (flags & flags_needed) == flags_needed; 218 } 219 220 /* reverse direction will send packets to new source, so 221 * make sure such packets are invalid. 222 */ 223 static bool nf_seq_has_advanced(const struct nf_conn *old, const struct nf_conn *new) 224 { 225 return (__s32)(new->proto.tcp.seen[0].td_end - 226 old->proto.tcp.seen[0].td_end) > 0; 227 } 228 229 static int 230 nf_nat_used_tuple_harder(const struct nf_conntrack_tuple *tuple, 231 const struct nf_conn *ignored_conntrack, 232 unsigned int attempts_left) 233 { 234 static const unsigned long flags_offload = IPS_OFFLOAD | IPS_HW_OFFLOAD; 235 struct nf_conntrack_tuple_hash *thash; 236 const struct nf_conntrack_zone *zone; 237 struct nf_conntrack_tuple reply; 238 unsigned long flags; 239 struct nf_conn *ct; 240 bool taken = true; 241 struct net *net; 242 243 nf_ct_invert_tuple(&reply, tuple); 244 245 if (attempts_left > NF_NAT_HARDER_THRESH || 246 tuple->dst.protonum != IPPROTO_TCP || 247 ignored_conntrack->proto.tcp.state != TCP_CONNTRACK_SYN_SENT) 248 return nf_conntrack_tuple_taken(&reply, ignored_conntrack); 249 250 /* :ast few attempts to find a free tcp port. Destructive 251 * action: evict colliding if its in timewait state and the 252 * tcp sequence number has advanced past the one used by the 253 * old entry. 254 */ 255 net = nf_ct_net(ignored_conntrack); 256 zone = nf_ct_zone(ignored_conntrack); 257 258 thash = nf_conntrack_find_get(net, zone, &reply); 259 if (!thash) 260 return false; 261 262 ct = nf_ct_tuplehash_to_ctrack(thash); 263 264 if (thash->tuple.dst.dir == IP_CT_DIR_ORIGINAL) 265 goto out; 266 267 if (WARN_ON_ONCE(ct == ignored_conntrack)) 268 goto out; 269 270 flags = READ_ONCE(ct->status); 271 if (!nf_nat_may_kill(ct, flags)) 272 goto out; 273 274 if (!nf_seq_has_advanced(ct, ignored_conntrack)) 275 goto out; 276 277 /* Even if we can evict do not reuse if entry is offloaded. */ 278 if (nf_ct_kill(ct)) 279 taken = flags & flags_offload; 280 out: 281 nf_ct_put(ct); 282 return taken; 283 } 284 285 static bool nf_nat_inet_in_range(const struct nf_conntrack_tuple *t, 286 const struct nf_nat_range2 *range) 287 { 288 if (t->src.l3num == NFPROTO_IPV4) 289 return ntohl(t->src.u3.ip) >= ntohl(range->min_addr.ip) && 290 ntohl(t->src.u3.ip) <= ntohl(range->max_addr.ip); 291 292 return ipv6_addr_cmp(&t->src.u3.in6, &range->min_addr.in6) >= 0 && 293 ipv6_addr_cmp(&t->src.u3.in6, &range->max_addr.in6) <= 0; 294 } 295 296 /* Is the manipable part of the tuple between min and max incl? */ 297 static bool l4proto_in_range(const struct nf_conntrack_tuple *tuple, 298 enum nf_nat_manip_type maniptype, 299 const union nf_conntrack_man_proto *min, 300 const union nf_conntrack_man_proto *max) 301 { 302 __be16 port; 303 304 switch (tuple->dst.protonum) { 305 case IPPROTO_ICMP: 306 case IPPROTO_ICMPV6: 307 return ntohs(tuple->src.u.icmp.id) >= ntohs(min->icmp.id) && 308 ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id); 309 case IPPROTO_GRE: /* all fall though */ 310 case IPPROTO_TCP: 311 case IPPROTO_UDP: 312 case IPPROTO_UDPLITE: 313 case IPPROTO_DCCP: 314 case IPPROTO_SCTP: 315 if (maniptype == NF_NAT_MANIP_SRC) 316 port = tuple->src.u.all; 317 else 318 port = tuple->dst.u.all; 319 320 return ntohs(port) >= ntohs(min->all) && 321 ntohs(port) <= ntohs(max->all); 322 default: 323 return true; 324 } 325 } 326 327 /* If we source map this tuple so reply looks like reply_tuple, will 328 * that meet the constraints of range. 329 */ 330 static int in_range(const struct nf_conntrack_tuple *tuple, 331 const struct nf_nat_range2 *range) 332 { 333 /* If we are supposed to map IPs, then we must be in the 334 * range specified, otherwise let this drag us onto a new src IP. 335 */ 336 if (range->flags & NF_NAT_RANGE_MAP_IPS && 337 !nf_nat_inet_in_range(tuple, range)) 338 return 0; 339 340 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) 341 return 1; 342 343 return l4proto_in_range(tuple, NF_NAT_MANIP_SRC, 344 &range->min_proto, &range->max_proto); 345 } 346 347 static inline int 348 same_src(const struct nf_conn *ct, 349 const struct nf_conntrack_tuple *tuple) 350 { 351 const struct nf_conntrack_tuple *t; 352 353 t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; 354 return (t->dst.protonum == tuple->dst.protonum && 355 nf_inet_addr_cmp(&t->src.u3, &tuple->src.u3) && 356 t->src.u.all == tuple->src.u.all); 357 } 358 359 /* Only called for SRC manip */ 360 static int 361 find_appropriate_src(struct net *net, 362 const struct nf_conntrack_zone *zone, 363 const struct nf_conntrack_tuple *tuple, 364 struct nf_conntrack_tuple *result, 365 const struct nf_nat_range2 *range) 366 { 367 unsigned int h = hash_by_src(net, zone, tuple); 368 const struct nf_conn *ct; 369 370 hlist_for_each_entry_rcu(ct, &nf_nat_bysource[h], nat_bysource) { 371 if (same_src(ct, tuple) && 372 net_eq(net, nf_ct_net(ct)) && 373 nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL)) { 374 /* Copy source part from reply tuple. */ 375 nf_ct_invert_tuple(result, 376 &ct->tuplehash[IP_CT_DIR_REPLY].tuple); 377 result->dst = tuple->dst; 378 379 if (in_range(result, range)) 380 return 1; 381 } 382 } 383 return 0; 384 } 385 386 /* For [FUTURE] fragmentation handling, we want the least-used 387 * src-ip/dst-ip/proto triple. Fairness doesn't come into it. Thus 388 * if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports 389 * 1-65535, we don't do pro-rata allocation based on ports; we choose 390 * the ip with the lowest src-ip/dst-ip/proto usage. 391 */ 392 static void 393 find_best_ips_proto(const struct nf_conntrack_zone *zone, 394 struct nf_conntrack_tuple *tuple, 395 const struct nf_nat_range2 *range, 396 const struct nf_conn *ct, 397 enum nf_nat_manip_type maniptype) 398 { 399 union nf_inet_addr *var_ipp; 400 unsigned int i, max; 401 /* Host order */ 402 u32 minip, maxip, j, dist; 403 bool full_range; 404 405 /* No IP mapping? Do nothing. */ 406 if (!(range->flags & NF_NAT_RANGE_MAP_IPS)) 407 return; 408 409 if (maniptype == NF_NAT_MANIP_SRC) 410 var_ipp = &tuple->src.u3; 411 else 412 var_ipp = &tuple->dst.u3; 413 414 /* Fast path: only one choice. */ 415 if (nf_inet_addr_cmp(&range->min_addr, &range->max_addr)) { 416 *var_ipp = range->min_addr; 417 return; 418 } 419 420 if (nf_ct_l3num(ct) == NFPROTO_IPV4) 421 max = sizeof(var_ipp->ip) / sizeof(u32) - 1; 422 else 423 max = sizeof(var_ipp->ip6) / sizeof(u32) - 1; 424 425 /* Hashing source and destination IPs gives a fairly even 426 * spread in practice (if there are a small number of IPs 427 * involved, there usually aren't that many connections 428 * anyway). The consistency means that servers see the same 429 * client coming from the same IP (some Internet Banking sites 430 * like this), even across reboots. 431 */ 432 j = jhash2((u32 *)&tuple->src.u3, sizeof(tuple->src.u3) / sizeof(u32), 433 range->flags & NF_NAT_RANGE_PERSISTENT ? 434 0 : (__force u32)tuple->dst.u3.all[max] ^ zone->id); 435 436 full_range = false; 437 for (i = 0; i <= max; i++) { 438 /* If first bytes of the address are at the maximum, use the 439 * distance. Otherwise use the full range. 440 */ 441 if (!full_range) { 442 minip = ntohl((__force __be32)range->min_addr.all[i]); 443 maxip = ntohl((__force __be32)range->max_addr.all[i]); 444 dist = maxip - minip + 1; 445 } else { 446 minip = 0; 447 dist = ~0; 448 } 449 450 var_ipp->all[i] = (__force __u32) 451 htonl(minip + reciprocal_scale(j, dist)); 452 if (var_ipp->all[i] != range->max_addr.all[i]) 453 full_range = true; 454 455 if (!(range->flags & NF_NAT_RANGE_PERSISTENT)) 456 j ^= (__force u32)tuple->dst.u3.all[i]; 457 } 458 } 459 460 /* Alter the per-proto part of the tuple (depending on maniptype), to 461 * give a unique tuple in the given range if possible. 462 * 463 * Per-protocol part of tuple is initialized to the incoming packet. 464 */ 465 static void nf_nat_l4proto_unique_tuple(struct nf_conntrack_tuple *tuple, 466 const struct nf_nat_range2 *range, 467 enum nf_nat_manip_type maniptype, 468 const struct nf_conn *ct) 469 { 470 unsigned int range_size, min, max, i, attempts; 471 __be16 *keyptr; 472 u16 off; 473 474 switch (tuple->dst.protonum) { 475 case IPPROTO_ICMP: 476 case IPPROTO_ICMPV6: 477 /* id is same for either direction... */ 478 keyptr = &tuple->src.u.icmp.id; 479 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) { 480 min = 0; 481 range_size = 65536; 482 } else { 483 min = ntohs(range->min_proto.icmp.id); 484 range_size = ntohs(range->max_proto.icmp.id) - 485 ntohs(range->min_proto.icmp.id) + 1; 486 } 487 goto find_free_id; 488 #if IS_ENABLED(CONFIG_NF_CT_PROTO_GRE) 489 case IPPROTO_GRE: 490 /* If there is no master conntrack we are not PPTP, 491 do not change tuples */ 492 if (!ct->master) 493 return; 494 495 if (maniptype == NF_NAT_MANIP_SRC) 496 keyptr = &tuple->src.u.gre.key; 497 else 498 keyptr = &tuple->dst.u.gre.key; 499 500 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) { 501 min = 1; 502 range_size = 65535; 503 } else { 504 min = ntohs(range->min_proto.gre.key); 505 range_size = ntohs(range->max_proto.gre.key) - min + 1; 506 } 507 goto find_free_id; 508 #endif 509 case IPPROTO_UDP: 510 case IPPROTO_UDPLITE: 511 case IPPROTO_TCP: 512 case IPPROTO_SCTP: 513 case IPPROTO_DCCP: 514 if (maniptype == NF_NAT_MANIP_SRC) 515 keyptr = &tuple->src.u.all; 516 else 517 keyptr = &tuple->dst.u.all; 518 519 break; 520 default: 521 return; 522 } 523 524 /* If no range specified... */ 525 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) { 526 /* If it's dst rewrite, can't change port */ 527 if (maniptype == NF_NAT_MANIP_DST) 528 return; 529 530 if (ntohs(*keyptr) < 1024) { 531 /* Loose convention: >> 512 is credential passing */ 532 if (ntohs(*keyptr) < 512) { 533 min = 1; 534 range_size = 511 - min + 1; 535 } else { 536 min = 600; 537 range_size = 1023 - min + 1; 538 } 539 } else { 540 min = 1024; 541 range_size = 65535 - 1024 + 1; 542 } 543 } else { 544 min = ntohs(range->min_proto.all); 545 max = ntohs(range->max_proto.all); 546 if (unlikely(max < min)) 547 swap(max, min); 548 range_size = max - min + 1; 549 } 550 551 find_free_id: 552 if (range->flags & NF_NAT_RANGE_PROTO_OFFSET) 553 off = (ntohs(*keyptr) - ntohs(range->base_proto.all)); 554 else 555 off = get_random_u16(); 556 557 attempts = range_size; 558 if (attempts > NF_NAT_MAX_ATTEMPTS) 559 attempts = NF_NAT_MAX_ATTEMPTS; 560 561 /* We are in softirq; doing a search of the entire range risks 562 * soft lockup when all tuples are already used. 563 * 564 * If we can't find any free port from first offset, pick a new 565 * one and try again, with ever smaller search window. 566 */ 567 another_round: 568 for (i = 0; i < attempts; i++, off++) { 569 *keyptr = htons(min + off % range_size); 570 if (!nf_nat_used_tuple_harder(tuple, ct, attempts - i)) 571 return; 572 } 573 574 if (attempts >= range_size || attempts < 16) 575 return; 576 attempts /= 2; 577 off = get_random_u16(); 578 goto another_round; 579 } 580 581 /* Manipulate the tuple into the range given. For NF_INET_POST_ROUTING, 582 * we change the source to map into the range. For NF_INET_PRE_ROUTING 583 * and NF_INET_LOCAL_OUT, we change the destination to map into the 584 * range. It might not be possible to get a unique tuple, but we try. 585 * At worst (or if we race), we will end up with a final duplicate in 586 * __nf_conntrack_confirm and drop the packet. */ 587 static void 588 get_unique_tuple(struct nf_conntrack_tuple *tuple, 589 const struct nf_conntrack_tuple *orig_tuple, 590 const struct nf_nat_range2 *range, 591 struct nf_conn *ct, 592 enum nf_nat_manip_type maniptype) 593 { 594 const struct nf_conntrack_zone *zone; 595 struct net *net = nf_ct_net(ct); 596 597 zone = nf_ct_zone(ct); 598 599 /* 1) If this srcip/proto/src-proto-part is currently mapped, 600 * and that same mapping gives a unique tuple within the given 601 * range, use that. 602 * 603 * This is only required for source (ie. NAT/masq) mappings. 604 * So far, we don't do local source mappings, so multiple 605 * manips not an issue. 606 */ 607 if (maniptype == NF_NAT_MANIP_SRC && 608 !(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) { 609 /* try the original tuple first */ 610 if (in_range(orig_tuple, range)) { 611 if (!nf_nat_used_tuple(orig_tuple, ct)) { 612 *tuple = *orig_tuple; 613 return; 614 } 615 } else if (find_appropriate_src(net, zone, 616 orig_tuple, tuple, range)) { 617 pr_debug("get_unique_tuple: Found current src map\n"); 618 if (!nf_nat_used_tuple(tuple, ct)) 619 return; 620 } 621 } 622 623 /* 2) Select the least-used IP/proto combination in the given range */ 624 *tuple = *orig_tuple; 625 find_best_ips_proto(zone, tuple, range, ct, maniptype); 626 627 /* 3) The per-protocol part of the manip is made to map into 628 * the range to make a unique tuple. 629 */ 630 631 /* Only bother mapping if it's not already in range and unique */ 632 if (!(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) { 633 if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) { 634 if (!(range->flags & NF_NAT_RANGE_PROTO_OFFSET) && 635 l4proto_in_range(tuple, maniptype, 636 &range->min_proto, 637 &range->max_proto) && 638 (range->min_proto.all == range->max_proto.all || 639 !nf_nat_used_tuple(tuple, ct))) 640 return; 641 } else if (!nf_nat_used_tuple(tuple, ct)) { 642 return; 643 } 644 } 645 646 /* Last chance: get protocol to try to obtain unique tuple. */ 647 nf_nat_l4proto_unique_tuple(tuple, range, maniptype, ct); 648 } 649 650 struct nf_conn_nat *nf_ct_nat_ext_add(struct nf_conn *ct) 651 { 652 struct nf_conn_nat *nat = nfct_nat(ct); 653 if (nat) 654 return nat; 655 656 if (!nf_ct_is_confirmed(ct)) 657 nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC); 658 659 return nat; 660 } 661 EXPORT_SYMBOL_GPL(nf_ct_nat_ext_add); 662 663 unsigned int 664 nf_nat_setup_info(struct nf_conn *ct, 665 const struct nf_nat_range2 *range, 666 enum nf_nat_manip_type maniptype) 667 { 668 struct net *net = nf_ct_net(ct); 669 struct nf_conntrack_tuple curr_tuple, new_tuple; 670 671 /* Can't setup nat info for confirmed ct. */ 672 if (nf_ct_is_confirmed(ct)) 673 return NF_ACCEPT; 674 675 WARN_ON(maniptype != NF_NAT_MANIP_SRC && 676 maniptype != NF_NAT_MANIP_DST); 677 678 if (WARN_ON(nf_nat_initialized(ct, maniptype))) 679 return NF_DROP; 680 681 /* What we've got will look like inverse of reply. Normally 682 * this is what is in the conntrack, except for prior 683 * manipulations (future optimization: if num_manips == 0, 684 * orig_tp = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple) 685 */ 686 nf_ct_invert_tuple(&curr_tuple, 687 &ct->tuplehash[IP_CT_DIR_REPLY].tuple); 688 689 get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype); 690 691 if (!nf_ct_tuple_equal(&new_tuple, &curr_tuple)) { 692 struct nf_conntrack_tuple reply; 693 694 /* Alter conntrack table so will recognize replies. */ 695 nf_ct_invert_tuple(&reply, &new_tuple); 696 nf_conntrack_alter_reply(ct, &reply); 697 698 /* Non-atomic: we own this at the moment. */ 699 if (maniptype == NF_NAT_MANIP_SRC) 700 ct->status |= IPS_SRC_NAT; 701 else 702 ct->status |= IPS_DST_NAT; 703 704 if (nfct_help(ct) && !nfct_seqadj(ct)) 705 if (!nfct_seqadj_ext_add(ct)) 706 return NF_DROP; 707 } 708 709 if (maniptype == NF_NAT_MANIP_SRC) { 710 unsigned int srchash; 711 spinlock_t *lock; 712 713 srchash = hash_by_src(net, nf_ct_zone(ct), 714 &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); 715 lock = &nf_nat_locks[srchash % CONNTRACK_LOCKS]; 716 spin_lock_bh(lock); 717 hlist_add_head_rcu(&ct->nat_bysource, 718 &nf_nat_bysource[srchash]); 719 spin_unlock_bh(lock); 720 } 721 722 /* It's done. */ 723 if (maniptype == NF_NAT_MANIP_DST) 724 ct->status |= IPS_DST_NAT_DONE; 725 else 726 ct->status |= IPS_SRC_NAT_DONE; 727 728 return NF_ACCEPT; 729 } 730 EXPORT_SYMBOL(nf_nat_setup_info); 731 732 static unsigned int 733 __nf_nat_alloc_null_binding(struct nf_conn *ct, enum nf_nat_manip_type manip) 734 { 735 /* Force range to this IP; let proto decide mapping for 736 * per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED). 737 * Use reply in case it's already been mangled (eg local packet). 738 */ 739 union nf_inet_addr ip = 740 (manip == NF_NAT_MANIP_SRC ? 741 ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3 : 742 ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3); 743 struct nf_nat_range2 range = { 744 .flags = NF_NAT_RANGE_MAP_IPS, 745 .min_addr = ip, 746 .max_addr = ip, 747 }; 748 return nf_nat_setup_info(ct, &range, manip); 749 } 750 751 unsigned int 752 nf_nat_alloc_null_binding(struct nf_conn *ct, unsigned int hooknum) 753 { 754 return __nf_nat_alloc_null_binding(ct, HOOK2MANIP(hooknum)); 755 } 756 EXPORT_SYMBOL_GPL(nf_nat_alloc_null_binding); 757 758 /* Do packet manipulations according to nf_nat_setup_info. */ 759 unsigned int nf_nat_packet(struct nf_conn *ct, 760 enum ip_conntrack_info ctinfo, 761 unsigned int hooknum, 762 struct sk_buff *skb) 763 { 764 enum nf_nat_manip_type mtype = HOOK2MANIP(hooknum); 765 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); 766 unsigned int verdict = NF_ACCEPT; 767 unsigned long statusbit; 768 769 if (mtype == NF_NAT_MANIP_SRC) 770 statusbit = IPS_SRC_NAT; 771 else 772 statusbit = IPS_DST_NAT; 773 774 /* Invert if this is reply dir. */ 775 if (dir == IP_CT_DIR_REPLY) 776 statusbit ^= IPS_NAT_MASK; 777 778 /* Non-atomic: these bits don't change. */ 779 if (ct->status & statusbit) 780 verdict = nf_nat_manip_pkt(skb, ct, mtype, dir); 781 782 return verdict; 783 } 784 EXPORT_SYMBOL_GPL(nf_nat_packet); 785 786 static bool in_vrf_postrouting(const struct nf_hook_state *state) 787 { 788 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 789 if (state->hook == NF_INET_POST_ROUTING && 790 netif_is_l3_master(state->out)) 791 return true; 792 #endif 793 return false; 794 } 795 796 unsigned int 797 nf_nat_inet_fn(void *priv, struct sk_buff *skb, 798 const struct nf_hook_state *state) 799 { 800 struct nf_conn *ct; 801 enum ip_conntrack_info ctinfo; 802 struct nf_conn_nat *nat; 803 /* maniptype == SRC for postrouting. */ 804 enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook); 805 806 ct = nf_ct_get(skb, &ctinfo); 807 /* Can't track? It's not due to stress, or conntrack would 808 * have dropped it. Hence it's the user's responsibilty to 809 * packet filter it out, or implement conntrack/NAT for that 810 * protocol. 8) --RR 811 */ 812 if (!ct || in_vrf_postrouting(state)) 813 return NF_ACCEPT; 814 815 nat = nfct_nat(ct); 816 817 switch (ctinfo) { 818 case IP_CT_RELATED: 819 case IP_CT_RELATED_REPLY: 820 /* Only ICMPs can be IP_CT_IS_REPLY. Fallthrough */ 821 case IP_CT_NEW: 822 /* Seen it before? This can happen for loopback, retrans, 823 * or local packets. 824 */ 825 if (!nf_nat_initialized(ct, maniptype)) { 826 struct nf_nat_lookup_hook_priv *lpriv = priv; 827 struct nf_hook_entries *e = rcu_dereference(lpriv->entries); 828 unsigned int ret; 829 int i; 830 831 if (!e) 832 goto null_bind; 833 834 for (i = 0; i < e->num_hook_entries; i++) { 835 ret = e->hooks[i].hook(e->hooks[i].priv, skb, 836 state); 837 if (ret != NF_ACCEPT) 838 return ret; 839 if (nf_nat_initialized(ct, maniptype)) 840 goto do_nat; 841 } 842 null_bind: 843 ret = nf_nat_alloc_null_binding(ct, state->hook); 844 if (ret != NF_ACCEPT) 845 return ret; 846 } else { 847 pr_debug("Already setup manip %s for ct %p (status bits 0x%lx)\n", 848 maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST", 849 ct, ct->status); 850 if (nf_nat_oif_changed(state->hook, ctinfo, nat, 851 state->out)) 852 goto oif_changed; 853 } 854 break; 855 default: 856 /* ESTABLISHED */ 857 WARN_ON(ctinfo != IP_CT_ESTABLISHED && 858 ctinfo != IP_CT_ESTABLISHED_REPLY); 859 if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out)) 860 goto oif_changed; 861 } 862 do_nat: 863 return nf_nat_packet(ct, ctinfo, state->hook, skb); 864 865 oif_changed: 866 nf_ct_kill_acct(ct, ctinfo, skb); 867 return NF_DROP; 868 } 869 EXPORT_SYMBOL_GPL(nf_nat_inet_fn); 870 871 struct nf_nat_proto_clean { 872 u8 l3proto; 873 u8 l4proto; 874 }; 875 876 /* kill conntracks with affected NAT section */ 877 static int nf_nat_proto_remove(struct nf_conn *i, void *data) 878 { 879 const struct nf_nat_proto_clean *clean = data; 880 881 if ((clean->l3proto && nf_ct_l3num(i) != clean->l3proto) || 882 (clean->l4proto && nf_ct_protonum(i) != clean->l4proto)) 883 return 0; 884 885 return i->status & IPS_NAT_MASK ? 1 : 0; 886 } 887 888 static void nf_nat_cleanup_conntrack(struct nf_conn *ct) 889 { 890 unsigned int h; 891 892 h = hash_by_src(nf_ct_net(ct), nf_ct_zone(ct), &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); 893 spin_lock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]); 894 hlist_del_rcu(&ct->nat_bysource); 895 spin_unlock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]); 896 } 897 898 static int nf_nat_proto_clean(struct nf_conn *ct, void *data) 899 { 900 if (nf_nat_proto_remove(ct, data)) 901 return 1; 902 903 /* This module is being removed and conntrack has nat null binding. 904 * Remove it from bysource hash, as the table will be freed soon. 905 * 906 * Else, when the conntrack is destoyed, nf_nat_cleanup_conntrack() 907 * will delete entry from already-freed table. 908 */ 909 if (test_and_clear_bit(IPS_SRC_NAT_DONE_BIT, &ct->status)) 910 nf_nat_cleanup_conntrack(ct); 911 912 /* don't delete conntrack. Although that would make things a lot 913 * simpler, we'd end up flushing all conntracks on nat rmmod. 914 */ 915 return 0; 916 } 917 918 #if IS_ENABLED(CONFIG_NF_CT_NETLINK) 919 920 #include <linux/netfilter/nfnetlink.h> 921 #include <linux/netfilter/nfnetlink_conntrack.h> 922 923 static const struct nla_policy protonat_nla_policy[CTA_PROTONAT_MAX+1] = { 924 [CTA_PROTONAT_PORT_MIN] = { .type = NLA_U16 }, 925 [CTA_PROTONAT_PORT_MAX] = { .type = NLA_U16 }, 926 }; 927 928 static int nf_nat_l4proto_nlattr_to_range(struct nlattr *tb[], 929 struct nf_nat_range2 *range) 930 { 931 if (tb[CTA_PROTONAT_PORT_MIN]) { 932 range->min_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MIN]); 933 range->max_proto.all = range->min_proto.all; 934 range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED; 935 } 936 if (tb[CTA_PROTONAT_PORT_MAX]) { 937 range->max_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MAX]); 938 range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED; 939 } 940 return 0; 941 } 942 943 static int nfnetlink_parse_nat_proto(struct nlattr *attr, 944 const struct nf_conn *ct, 945 struct nf_nat_range2 *range) 946 { 947 struct nlattr *tb[CTA_PROTONAT_MAX+1]; 948 int err; 949 950 err = nla_parse_nested_deprecated(tb, CTA_PROTONAT_MAX, attr, 951 protonat_nla_policy, NULL); 952 if (err < 0) 953 return err; 954 955 return nf_nat_l4proto_nlattr_to_range(tb, range); 956 } 957 958 static const struct nla_policy nat_nla_policy[CTA_NAT_MAX+1] = { 959 [CTA_NAT_V4_MINIP] = { .type = NLA_U32 }, 960 [CTA_NAT_V4_MAXIP] = { .type = NLA_U32 }, 961 [CTA_NAT_V6_MINIP] = { .len = sizeof(struct in6_addr) }, 962 [CTA_NAT_V6_MAXIP] = { .len = sizeof(struct in6_addr) }, 963 [CTA_NAT_PROTO] = { .type = NLA_NESTED }, 964 }; 965 966 static int nf_nat_ipv4_nlattr_to_range(struct nlattr *tb[], 967 struct nf_nat_range2 *range) 968 { 969 if (tb[CTA_NAT_V4_MINIP]) { 970 range->min_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MINIP]); 971 range->flags |= NF_NAT_RANGE_MAP_IPS; 972 } 973 974 if (tb[CTA_NAT_V4_MAXIP]) 975 range->max_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MAXIP]); 976 else 977 range->max_addr.ip = range->min_addr.ip; 978 979 return 0; 980 } 981 982 static int nf_nat_ipv6_nlattr_to_range(struct nlattr *tb[], 983 struct nf_nat_range2 *range) 984 { 985 if (tb[CTA_NAT_V6_MINIP]) { 986 nla_memcpy(&range->min_addr.ip6, tb[CTA_NAT_V6_MINIP], 987 sizeof(struct in6_addr)); 988 range->flags |= NF_NAT_RANGE_MAP_IPS; 989 } 990 991 if (tb[CTA_NAT_V6_MAXIP]) 992 nla_memcpy(&range->max_addr.ip6, tb[CTA_NAT_V6_MAXIP], 993 sizeof(struct in6_addr)); 994 else 995 range->max_addr = range->min_addr; 996 997 return 0; 998 } 999 1000 static int 1001 nfnetlink_parse_nat(const struct nlattr *nat, 1002 const struct nf_conn *ct, struct nf_nat_range2 *range) 1003 { 1004 struct nlattr *tb[CTA_NAT_MAX+1]; 1005 int err; 1006 1007 memset(range, 0, sizeof(*range)); 1008 1009 err = nla_parse_nested_deprecated(tb, CTA_NAT_MAX, nat, 1010 nat_nla_policy, NULL); 1011 if (err < 0) 1012 return err; 1013 1014 switch (nf_ct_l3num(ct)) { 1015 case NFPROTO_IPV4: 1016 err = nf_nat_ipv4_nlattr_to_range(tb, range); 1017 break; 1018 case NFPROTO_IPV6: 1019 err = nf_nat_ipv6_nlattr_to_range(tb, range); 1020 break; 1021 default: 1022 err = -EPROTONOSUPPORT; 1023 break; 1024 } 1025 1026 if (err) 1027 return err; 1028 1029 if (!tb[CTA_NAT_PROTO]) 1030 return 0; 1031 1032 return nfnetlink_parse_nat_proto(tb[CTA_NAT_PROTO], ct, range); 1033 } 1034 1035 /* This function is called under rcu_read_lock() */ 1036 static int 1037 nfnetlink_parse_nat_setup(struct nf_conn *ct, 1038 enum nf_nat_manip_type manip, 1039 const struct nlattr *attr) 1040 { 1041 struct nf_nat_range2 range; 1042 int err; 1043 1044 /* Should not happen, restricted to creating new conntracks 1045 * via ctnetlink. 1046 */ 1047 if (WARN_ON_ONCE(nf_nat_initialized(ct, manip))) 1048 return -EEXIST; 1049 1050 /* No NAT information has been passed, allocate the null-binding */ 1051 if (attr == NULL) 1052 return __nf_nat_alloc_null_binding(ct, manip) == NF_DROP ? -ENOMEM : 0; 1053 1054 err = nfnetlink_parse_nat(attr, ct, &range); 1055 if (err < 0) 1056 return err; 1057 1058 return nf_nat_setup_info(ct, &range, manip) == NF_DROP ? -ENOMEM : 0; 1059 } 1060 #else 1061 static int 1062 nfnetlink_parse_nat_setup(struct nf_conn *ct, 1063 enum nf_nat_manip_type manip, 1064 const struct nlattr *attr) 1065 { 1066 return -EOPNOTSUPP; 1067 } 1068 #endif 1069 1070 static struct nf_ct_helper_expectfn follow_master_nat = { 1071 .name = "nat-follow-master", 1072 .expectfn = nf_nat_follow_master, 1073 }; 1074 1075 int nf_nat_register_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops, 1076 const struct nf_hook_ops *orig_nat_ops, unsigned int ops_count) 1077 { 1078 struct nat_net *nat_net = net_generic(net, nat_net_id); 1079 struct nf_nat_hooks_net *nat_proto_net; 1080 struct nf_nat_lookup_hook_priv *priv; 1081 unsigned int hooknum = ops->hooknum; 1082 struct nf_hook_ops *nat_ops; 1083 int i, ret; 1084 1085 if (WARN_ON_ONCE(pf >= ARRAY_SIZE(nat_net->nat_proto_net))) 1086 return -EINVAL; 1087 1088 nat_proto_net = &nat_net->nat_proto_net[pf]; 1089 1090 for (i = 0; i < ops_count; i++) { 1091 if (orig_nat_ops[i].hooknum == hooknum) { 1092 hooknum = i; 1093 break; 1094 } 1095 } 1096 1097 if (WARN_ON_ONCE(i == ops_count)) 1098 return -EINVAL; 1099 1100 mutex_lock(&nf_nat_proto_mutex); 1101 if (!nat_proto_net->nat_hook_ops) { 1102 WARN_ON(nat_proto_net->users != 0); 1103 1104 nat_ops = kmemdup(orig_nat_ops, sizeof(*orig_nat_ops) * ops_count, GFP_KERNEL); 1105 if (!nat_ops) { 1106 mutex_unlock(&nf_nat_proto_mutex); 1107 return -ENOMEM; 1108 } 1109 1110 for (i = 0; i < ops_count; i++) { 1111 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 1112 if (priv) { 1113 nat_ops[i].priv = priv; 1114 continue; 1115 } 1116 mutex_unlock(&nf_nat_proto_mutex); 1117 while (i) 1118 kfree(nat_ops[--i].priv); 1119 kfree(nat_ops); 1120 return -ENOMEM; 1121 } 1122 1123 ret = nf_register_net_hooks(net, nat_ops, ops_count); 1124 if (ret < 0) { 1125 mutex_unlock(&nf_nat_proto_mutex); 1126 for (i = 0; i < ops_count; i++) 1127 kfree(nat_ops[i].priv); 1128 kfree(nat_ops); 1129 return ret; 1130 } 1131 1132 nat_proto_net->nat_hook_ops = nat_ops; 1133 } 1134 1135 nat_ops = nat_proto_net->nat_hook_ops; 1136 priv = nat_ops[hooknum].priv; 1137 if (WARN_ON_ONCE(!priv)) { 1138 mutex_unlock(&nf_nat_proto_mutex); 1139 return -EOPNOTSUPP; 1140 } 1141 1142 ret = nf_hook_entries_insert_raw(&priv->entries, ops); 1143 if (ret == 0) 1144 nat_proto_net->users++; 1145 1146 mutex_unlock(&nf_nat_proto_mutex); 1147 return ret; 1148 } 1149 1150 void nf_nat_unregister_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops, 1151 unsigned int ops_count) 1152 { 1153 struct nat_net *nat_net = net_generic(net, nat_net_id); 1154 struct nf_nat_hooks_net *nat_proto_net; 1155 struct nf_nat_lookup_hook_priv *priv; 1156 struct nf_hook_ops *nat_ops; 1157 int hooknum = ops->hooknum; 1158 int i; 1159 1160 if (pf >= ARRAY_SIZE(nat_net->nat_proto_net)) 1161 return; 1162 1163 nat_proto_net = &nat_net->nat_proto_net[pf]; 1164 1165 mutex_lock(&nf_nat_proto_mutex); 1166 if (WARN_ON(nat_proto_net->users == 0)) 1167 goto unlock; 1168 1169 nat_proto_net->users--; 1170 1171 nat_ops = nat_proto_net->nat_hook_ops; 1172 for (i = 0; i < ops_count; i++) { 1173 if (nat_ops[i].hooknum == hooknum) { 1174 hooknum = i; 1175 break; 1176 } 1177 } 1178 if (WARN_ON_ONCE(i == ops_count)) 1179 goto unlock; 1180 priv = nat_ops[hooknum].priv; 1181 nf_hook_entries_delete_raw(&priv->entries, ops); 1182 1183 if (nat_proto_net->users == 0) { 1184 nf_unregister_net_hooks(net, nat_ops, ops_count); 1185 1186 for (i = 0; i < ops_count; i++) { 1187 priv = nat_ops[i].priv; 1188 kfree_rcu(priv, rcu_head); 1189 } 1190 1191 nat_proto_net->nat_hook_ops = NULL; 1192 kfree(nat_ops); 1193 } 1194 unlock: 1195 mutex_unlock(&nf_nat_proto_mutex); 1196 } 1197 1198 static struct pernet_operations nat_net_ops = { 1199 .id = &nat_net_id, 1200 .size = sizeof(struct nat_net), 1201 }; 1202 1203 static const struct nf_nat_hook nat_hook = { 1204 .parse_nat_setup = nfnetlink_parse_nat_setup, 1205 #ifdef CONFIG_XFRM 1206 .decode_session = __nf_nat_decode_session, 1207 #endif 1208 .manip_pkt = nf_nat_manip_pkt, 1209 .remove_nat_bysrc = nf_nat_cleanup_conntrack, 1210 }; 1211 1212 static int __init nf_nat_init(void) 1213 { 1214 int ret, i; 1215 1216 /* Leave them the same for the moment. */ 1217 nf_nat_htable_size = nf_conntrack_htable_size; 1218 if (nf_nat_htable_size < CONNTRACK_LOCKS) 1219 nf_nat_htable_size = CONNTRACK_LOCKS; 1220 1221 nf_nat_bysource = nf_ct_alloc_hashtable(&nf_nat_htable_size, 0); 1222 if (!nf_nat_bysource) 1223 return -ENOMEM; 1224 1225 for (i = 0; i < CONNTRACK_LOCKS; i++) 1226 spin_lock_init(&nf_nat_locks[i]); 1227 1228 ret = register_pernet_subsys(&nat_net_ops); 1229 if (ret < 0) { 1230 kvfree(nf_nat_bysource); 1231 return ret; 1232 } 1233 1234 nf_ct_helper_expectfn_register(&follow_master_nat); 1235 1236 WARN_ON(nf_nat_hook != NULL); 1237 RCU_INIT_POINTER(nf_nat_hook, &nat_hook); 1238 1239 ret = register_nf_nat_bpf(); 1240 if (ret < 0) { 1241 RCU_INIT_POINTER(nf_nat_hook, NULL); 1242 nf_ct_helper_expectfn_unregister(&follow_master_nat); 1243 synchronize_net(); 1244 unregister_pernet_subsys(&nat_net_ops); 1245 kvfree(nf_nat_bysource); 1246 } 1247 1248 return ret; 1249 } 1250 1251 static void __exit nf_nat_cleanup(void) 1252 { 1253 struct nf_nat_proto_clean clean = {}; 1254 1255 nf_ct_iterate_destroy(nf_nat_proto_clean, &clean); 1256 1257 nf_ct_helper_expectfn_unregister(&follow_master_nat); 1258 RCU_INIT_POINTER(nf_nat_hook, NULL); 1259 1260 synchronize_net(); 1261 kvfree(nf_nat_bysource); 1262 unregister_pernet_subsys(&nat_net_ops); 1263 } 1264 1265 MODULE_LICENSE("GPL"); 1266 1267 module_init(nf_nat_init); 1268 module_exit(nf_nat_cleanup); 1269