net/netfilter/nf_nat_core.c

   1 /*
   2  * (C) 1999-2001 Paul `Rusty' Russell
   3  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
   4  * (C) 2011 Patrick McHardy <kaber@trash.net>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13 #include <linux/module.h>
  14 #include <linux/types.h>
  15 #include <linux/timer.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/gfp.h>
  18 #include <net/xfrm.h>
  19 #include <linux/jhash.h>
  20 #include <linux/rtnetlink.h>
  21
  22 #include <net/netfilter/nf_conntrack.h>
  23 #include <net/netfilter/nf_conntrack_core.h>
  24 #include <net/netfilter/nf_nat.h>
  25 #include <net/netfilter/nf_nat_helper.h>
  26 #include <net/netfilter/nf_conntrack_helper.h>
  27 #include <net/netfilter/nf_conntrack_seqadj.h>
  28 #include <net/netfilter/nf_conntrack_zones.h>
  29 #include <linux/netfilter/nf_nat.h>
  30
  31 #include "nf_internals.h"
  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 unsigned int nf_nat_hash_rnd __read_mostly;
  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
 153 int nf_xfrm_me_harder(struct net *net, struct sk_buff *skb, unsigned int family)
 154 {
 155         struct flowi fl;
 156         unsigned int hh_len;
 157         struct dst_entry *dst;
 158         struct sock *sk = skb->sk;
 159         int err;
 160
 161         err = xfrm_decode_session(skb, &fl, family);
 162         if (err < 0)
 163                 return err;
 164
 165         dst = skb_dst(skb);
 166         if (dst->xfrm)
 167                 dst = ((struct xfrm_dst *)dst)->route;
 168         if (!dst_hold_safe(dst))
 169                 return -EHOSTUNREACH;
 170
 171         if (sk && !net_eq(net, sock_net(sk)))
 172                 sk = NULL;
 173
 174         dst = xfrm_lookup(net, dst, &fl, sk, 0);
 175         if (IS_ERR(dst))
 176                 return PTR_ERR(dst);
 177
 178         skb_dst_drop(skb);
 179         skb_dst_set(skb, dst);
 180
 181         /* Change in oif may mean change in hh_len. */
 182         hh_len = skb_dst(skb)->dev->hard_header_len;
 183         if (skb_headroom(skb) < hh_len &&
 184             pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
 185                 return -ENOMEM;
 186         return 0;
 187 }
 188 EXPORT_SYMBOL(nf_xfrm_me_harder);
 189 #endif /* CONFIG_XFRM */
 190
 191 /* We keep an extra hash for each conntrack, for fast searching. */
 192 static unsigned int
 193 hash_by_src(const struct net *n, const struct nf_conntrack_tuple *tuple)
 194 {
 195         unsigned int hash;
 196
 197         get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd));
 198
 199         /* Original src, to ensure we map it consistently if poss. */
 200         hash = jhash2((u32 *)&tuple->src, sizeof(tuple->src) / sizeof(u32),
 201                       tuple->dst.protonum ^ nf_nat_hash_rnd ^ net_hash_mix(n));
 202
 203         return reciprocal_scale(hash, nf_nat_htable_size);
 204 }
 205
 206 /* Is this tuple already taken? (not by us) */
 207 static int
 208 nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple,
 209                   const struct nf_conn *ignored_conntrack)
 210 {
 211         /* Conntrack tracking doesn't keep track of outgoing tuples; only
 212          * incoming ones.  NAT means they don't have a fixed mapping,
 213          * so we invert the tuple and look for the incoming reply.
 214          *
 215          * We could keep a separate hash if this proves too slow.
 216          */
 217         struct nf_conntrack_tuple reply;
 218
 219         nf_ct_invert_tuple(&reply, tuple);
 220         return nf_conntrack_tuple_taken(&reply, ignored_conntrack);
 221 }
 222
 223 static bool nf_nat_inet_in_range(const struct nf_conntrack_tuple *t,
 224                                  const struct nf_nat_range2 *range)
 225 {
 226         if (t->src.l3num == NFPROTO_IPV4)
 227                 return ntohl(t->src.u3.ip) >= ntohl(range->min_addr.ip) &&
 228                        ntohl(t->src.u3.ip) <= ntohl(range->max_addr.ip);
 229
 230         return ipv6_addr_cmp(&t->src.u3.in6, &range->min_addr.in6) >= 0 &&
 231                ipv6_addr_cmp(&t->src.u3.in6, &range->max_addr.in6) <= 0;
 232 }
 233
 234 /* Is the manipable part of the tuple between min and max incl? */
 235 static bool l4proto_in_range(const struct nf_conntrack_tuple *tuple,
 236                              enum nf_nat_manip_type maniptype,
 237                              const union nf_conntrack_man_proto *min,
 238                              const union nf_conntrack_man_proto *max)
 239 {
 240         __be16 port;
 241
 242         switch (tuple->dst.protonum) {
 243         case IPPROTO_ICMP:
 244         case IPPROTO_ICMPV6:
 245                 return ntohs(tuple->src.u.icmp.id) >= ntohs(min->icmp.id) &&
 246                        ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id);
 247         case IPPROTO_GRE: /* all fall though */
 248         case IPPROTO_TCP:
 249         case IPPROTO_UDP:
 250         case IPPROTO_UDPLITE:
 251         case IPPROTO_DCCP:
 252         case IPPROTO_SCTP:
 253                 if (maniptype == NF_NAT_MANIP_SRC)
 254                         port = tuple->src.u.all;
 255                 else
 256                         port = tuple->dst.u.all;
 257
 258                 return ntohs(port) >= ntohs(min->all) &&
 259                        ntohs(port) <= ntohs(max->all);
 260         default:
 261                 return true;
 262         }
 263 }
 264
 265 /* If we source map this tuple so reply looks like reply_tuple, will
 266  * that meet the constraints of range.
 267  */
 268 static int in_range(const struct nf_conntrack_tuple *tuple,
 269                     const struct nf_nat_range2 *range)
 270 {
 271         /* If we are supposed to map IPs, then we must be in the
 272          * range specified, otherwise let this drag us onto a new src IP.
 273          */
 274         if (range->flags & NF_NAT_RANGE_MAP_IPS &&
 275             !nf_nat_inet_in_range(tuple, range))
 276                 return 0;
 277
 278         if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED))
 279                 return 1;
 280
 281         return l4proto_in_range(tuple, NF_NAT_MANIP_SRC,
 282                                 &range->min_proto, &range->max_proto);
 283 }
 284
 285 static inline int
 286 same_src(const struct nf_conn *ct,
 287          const struct nf_conntrack_tuple *tuple)
 288 {
 289         const struct nf_conntrack_tuple *t;
 290
 291         t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
 292         return (t->dst.protonum == tuple->dst.protonum &&
 293                 nf_inet_addr_cmp(&t->src.u3, &tuple->src.u3) &&
 294                 t->src.u.all == tuple->src.u.all);
 295 }
 296
 297 /* Only called for SRC manip */
 298 static int
 299 find_appropriate_src(struct net *net,
 300                      const struct nf_conntrack_zone *zone,
 301                      const struct nf_conntrack_tuple *tuple,
 302                      struct nf_conntrack_tuple *result,
 303                      const struct nf_nat_range2 *range)
 304 {
 305         unsigned int h = hash_by_src(net, tuple);
 306         const struct nf_conn *ct;
 307
 308         hlist_for_each_entry_rcu(ct, &nf_nat_bysource[h], nat_bysource) {
 309                 if (same_src(ct, tuple) &&
 310                     net_eq(net, nf_ct_net(ct)) &&
 311                     nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL)) {
 312                         /* Copy source part from reply tuple. */
 313                         nf_ct_invert_tuple(result,
 314                                        &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
 315                         result->dst = tuple->dst;
 316
 317                         if (in_range(result, range))
 318                                 return 1;
 319                 }
 320         }
 321         return 0;
 322 }
 323
 324 /* For [FUTURE] fragmentation handling, we want the least-used
 325  * src-ip/dst-ip/proto triple.  Fairness doesn't come into it.  Thus
 326  * if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports
 327  * 1-65535, we don't do pro-rata allocation based on ports; we choose
 328  * the ip with the lowest src-ip/dst-ip/proto usage.
 329  */
 330 static void
 331 find_best_ips_proto(const struct nf_conntrack_zone *zone,
 332                     struct nf_conntrack_tuple *tuple,
 333                     const struct nf_nat_range2 *range,
 334                     const struct nf_conn *ct,
 335                     enum nf_nat_manip_type maniptype)
 336 {
 337         union nf_inet_addr *var_ipp;
 338         unsigned int i, max;
 339         /* Host order */
 340         u32 minip, maxip, j, dist;
 341         bool full_range;
 342
 343         /* No IP mapping?  Do nothing. */
 344         if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
 345                 return;
 346
 347         if (maniptype == NF_NAT_MANIP_SRC)
 348                 var_ipp = &tuple->src.u3;
 349         else
 350                 var_ipp = &tuple->dst.u3;
 351
 352         /* Fast path: only one choice. */
 353         if (nf_inet_addr_cmp(&range->min_addr, &range->max_addr)) {
 354                 *var_ipp = range->min_addr;
 355                 return;
 356         }
 357
 358         if (nf_ct_l3num(ct) == NFPROTO_IPV4)
 359                 max = sizeof(var_ipp->ip) / sizeof(u32) - 1;
 360         else
 361                 max = sizeof(var_ipp->ip6) / sizeof(u32) - 1;
 362
 363         /* Hashing source and destination IPs gives a fairly even
 364          * spread in practice (if there are a small number of IPs
 365          * involved, there usually aren't that many connections
 366          * anyway).  The consistency means that servers see the same
 367          * client coming from the same IP (some Internet Banking sites
 368          * like this), even across reboots.
 369          */
 370         j = jhash2((u32 *)&tuple->src.u3, sizeof(tuple->src.u3) / sizeof(u32),
 371                    range->flags & NF_NAT_RANGE_PERSISTENT ?
 372                         0 : (__force u32)tuple->dst.u3.all[max] ^ zone->id);
 373
 374         full_range = false;
 375         for (i = 0; i <= max; i++) {
 376                 /* If first bytes of the address are at the maximum, use the
 377                  * distance. Otherwise use the full range.
 378                  */
 379                 if (!full_range) {
 380                         minip = ntohl((__force __be32)range->min_addr.all[i]);
 381                         maxip = ntohl((__force __be32)range->max_addr.all[i]);
 382                         dist  = maxip - minip + 1;
 383                 } else {
 384                         minip = 0;
 385                         dist  = ~0;
 386                 }
 387
 388                 var_ipp->all[i] = (__force __u32)
 389                         htonl(minip + reciprocal_scale(j, dist));
 390                 if (var_ipp->all[i] != range->max_addr.all[i])
 391                         full_range = true;
 392
 393                 if (!(range->flags & NF_NAT_RANGE_PERSISTENT))
 394                         j ^= (__force u32)tuple->dst.u3.all[i];
 395         }
 396 }
 397
 398 /* Alter the per-proto part of the tuple (depending on maniptype), to
 399  * give a unique tuple in the given range if possible.
 400  *
 401  * Per-protocol part of tuple is initialized to the incoming packet.
 402  */
 403 static void nf_nat_l4proto_unique_tuple(struct nf_conntrack_tuple *tuple,
 404                                         const struct nf_nat_range2 *range,
 405                                         enum nf_nat_manip_type maniptype,
 406                                         const struct nf_conn *ct)
 407 {
 408         unsigned int range_size, min, max, i, attempts;
 409         __be16 *keyptr;
 410         u16 off;
 411         static const unsigned int max_attempts = 128;
 412
 413         switch (tuple->dst.protonum) {
 414         case IPPROTO_ICMP: /* fallthrough */
 415         case IPPROTO_ICMPV6:
 416                 /* id is same for either direction... */
 417                 keyptr = &tuple->src.u.icmp.id;
 418                 min = range->min_proto.icmp.id;
 419                 range_size = ntohs(range->max_proto.icmp.id) -
 420                              ntohs(range->min_proto.icmp.id) + 1;
 421                 goto find_free_id;
 422 #if IS_ENABLED(CONFIG_NF_CT_PROTO_GRE)
 423         case IPPROTO_GRE:
 424                 /* If there is no master conntrack we are not PPTP,
 425                    do not change tuples */
 426                 if (!ct->master)
 427                         return;
 428
 429                 if (maniptype == NF_NAT_MANIP_SRC)
 430                         keyptr = &tuple->src.u.gre.key;
 431                 else
 432                         keyptr = &tuple->dst.u.gre.key;
 433
 434                 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
 435                         min = 1;
 436                         range_size = 65535;
 437                 } else {
 438                         min = ntohs(range->min_proto.gre.key);
 439                         range_size = ntohs(range->max_proto.gre.key) - min + 1;
 440                 }
 441                 goto find_free_id;
 442 #endif
 443         case IPPROTO_UDP:       /* fallthrough */
 444         case IPPROTO_UDPLITE:   /* fallthrough */
 445         case IPPROTO_TCP:       /* fallthrough */
 446         case IPPROTO_SCTP:      /* fallthrough */
 447         case IPPROTO_DCCP:      /* fallthrough */
 448                 if (maniptype == NF_NAT_MANIP_SRC)
 449                         keyptr = &tuple->src.u.all;
 450                 else
 451                         keyptr = &tuple->dst.u.all;
 452
 453                 break;
 454         default:
 455                 return;
 456         }
 457
 458         /* If no range specified... */
 459         if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
 460                 /* If it's dst rewrite, can't change port */
 461                 if (maniptype == NF_NAT_MANIP_DST)
 462                         return;
 463
 464                 if (ntohs(*keyptr) < 1024) {
 465                         /* Loose convention: >> 512 is credential passing */
 466                         if (ntohs(*keyptr) < 512) {
 467                                 min = 1;
 468                                 range_size = 511 - min + 1;
 469                         } else {
 470                                 min = 600;
 471                                 range_size = 1023 - min + 1;
 472                         }
 473                 } else {
 474                         min = 1024;
 475                         range_size = 65535 - 1024 + 1;
 476                 }
 477         } else {
 478                 min = ntohs(range->min_proto.all);
 479                 max = ntohs(range->max_proto.all);
 480                 if (unlikely(max < min))
 481                         swap(max, min);
 482                 range_size = max - min + 1;
 483         }
 484
 485 find_free_id:
 486         if (range->flags & NF_NAT_RANGE_PROTO_OFFSET)
 487                 off = (ntohs(*keyptr) - ntohs(range->base_proto.all));
 488         else
 489                 off = prandom_u32();
 490
 491         attempts = range_size;
 492         if (attempts > max_attempts)
 493                 attempts = max_attempts;
 494
 495         /* We are in softirq; doing a search of the entire range risks
 496          * soft lockup when all tuples are already used.
 497          *
 498          * If we can't find any free port from first offset, pick a new
 499          * one and try again, with ever smaller search window.
 500          */
 501 another_round:
 502         for (i = 0; i < attempts; i++, off++) {
 503                 *keyptr = htons(min + off % range_size);
 504                 if (!nf_nat_used_tuple(tuple, ct))
 505                         return;
 506         }
 507
 508         if (attempts >= range_size || attempts < 16)
 509                 return;
 510         attempts /= 2;
 511         off = prandom_u32();
 512         goto another_round;
 513 }
 514
 515 /* Manipulate the tuple into the range given. For NF_INET_POST_ROUTING,
 516  * we change the source to map into the range. For NF_INET_PRE_ROUTING
 517  * and NF_INET_LOCAL_OUT, we change the destination to map into the
 518  * range. It might not be possible to get a unique tuple, but we try.
 519  * At worst (or if we race), we will end up with a final duplicate in
 520  * __ip_conntrack_confirm and drop the packet. */
 521 static void
 522 get_unique_tuple(struct nf_conntrack_tuple *tuple,
 523                  const struct nf_conntrack_tuple *orig_tuple,
 524                  const struct nf_nat_range2 *range,
 525                  struct nf_conn *ct,
 526                  enum nf_nat_manip_type maniptype)
 527 {
 528         const struct nf_conntrack_zone *zone;
 529         struct net *net = nf_ct_net(ct);
 530
 531         zone = nf_ct_zone(ct);
 532
 533         /* 1) If this srcip/proto/src-proto-part is currently mapped,
 534          * and that same mapping gives a unique tuple within the given
 535          * range, use that.
 536          *
 537          * This is only required for source (ie. NAT/masq) mappings.
 538          * So far, we don't do local source mappings, so multiple
 539          * manips not an issue.
 540          */
 541         if (maniptype == NF_NAT_MANIP_SRC &&
 542             !(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
 543                 /* try the original tuple first */
 544                 if (in_range(orig_tuple, range)) {
 545                         if (!nf_nat_used_tuple(orig_tuple, ct)) {
 546                                 *tuple = *orig_tuple;
 547                                 return;
 548                         }
 549                 } else if (find_appropriate_src(net, zone,
 550                                                 orig_tuple, tuple, range)) {
 551                         pr_debug("get_unique_tuple: Found current src map\n");
 552                         if (!nf_nat_used_tuple(tuple, ct))
 553                                 return;
 554                 }
 555         }
 556
 557         /* 2) Select the least-used IP/proto combination in the given range */
 558         *tuple = *orig_tuple;
 559         find_best_ips_proto(zone, tuple, range, ct, maniptype);
 560
 561         /* 3) The per-protocol part of the manip is made to map into
 562          * the range to make a unique tuple.
 563          */
 564
 565         /* Only bother mapping if it's not already in range and unique */
 566         if (!(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
 567                 if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
 568                         if (!(range->flags & NF_NAT_RANGE_PROTO_OFFSET) &&
 569                             l4proto_in_range(tuple, maniptype,
 570                                   &range->min_proto,
 571                                   &range->max_proto) &&
 572                             (range->min_proto.all == range->max_proto.all ||
 573                              !nf_nat_used_tuple(tuple, ct)))
 574                                 return;
 575                 } else if (!nf_nat_used_tuple(tuple, ct)) {
 576                         return;
 577                 }
 578         }
 579
 580         /* Last chance: get protocol to try to obtain unique tuple. */
 581         nf_nat_l4proto_unique_tuple(tuple, range, maniptype, ct);
 582 }
 583
 584 struct nf_conn_nat *nf_ct_nat_ext_add(struct nf_conn *ct)
 585 {
 586         struct nf_conn_nat *nat = nfct_nat(ct);
 587         if (nat)
 588                 return nat;
 589
 590         if (!nf_ct_is_confirmed(ct))
 591                 nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
 592
 593         return nat;
 594 }
 595 EXPORT_SYMBOL_GPL(nf_ct_nat_ext_add);
 596
 597 unsigned int
 598 nf_nat_setup_info(struct nf_conn *ct,
 599                   const struct nf_nat_range2 *range,
 600                   enum nf_nat_manip_type maniptype)
 601 {
 602         struct net *net = nf_ct_net(ct);
 603         struct nf_conntrack_tuple curr_tuple, new_tuple;
 604
 605         /* Can't setup nat info for confirmed ct. */
 606         if (nf_ct_is_confirmed(ct))
 607                 return NF_ACCEPT;
 608
 609         WARN_ON(maniptype != NF_NAT_MANIP_SRC &&
 610                 maniptype != NF_NAT_MANIP_DST);
 611
 612         if (WARN_ON(nf_nat_initialized(ct, maniptype)))
 613                 return NF_DROP;
 614
 615         /* What we've got will look like inverse of reply. Normally
 616          * this is what is in the conntrack, except for prior
 617          * manipulations (future optimization: if num_manips == 0,
 618          * orig_tp = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple)
 619          */
 620         nf_ct_invert_tuple(&curr_tuple,
 621                            &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
 622
 623         get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype);
 624
 625         if (!nf_ct_tuple_equal(&new_tuple, &curr_tuple)) {
 626                 struct nf_conntrack_tuple reply;
 627
 628                 /* Alter conntrack table so will recognize replies. */
 629                 nf_ct_invert_tuple(&reply, &new_tuple);
 630                 nf_conntrack_alter_reply(ct, &reply);
 631
 632                 /* Non-atomic: we own this at the moment. */
 633                 if (maniptype == NF_NAT_MANIP_SRC)
 634                         ct->status |= IPS_SRC_NAT;
 635                 else
 636                         ct->status |= IPS_DST_NAT;
 637
 638                 if (nfct_help(ct) && !nfct_seqadj(ct))
 639                         if (!nfct_seqadj_ext_add(ct))
 640                                 return NF_DROP;
 641         }
 642
 643         if (maniptype == NF_NAT_MANIP_SRC) {
 644                 unsigned int srchash;
 645                 spinlock_t *lock;
 646
 647                 srchash = hash_by_src(net,
 648                                       &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
 649                 lock = &nf_nat_locks[srchash % CONNTRACK_LOCKS];
 650                 spin_lock_bh(lock);
 651                 hlist_add_head_rcu(&ct->nat_bysource,
 652                                    &nf_nat_bysource[srchash]);
 653                 spin_unlock_bh(lock);
 654         }
 655
 656         /* It's done. */
 657         if (maniptype == NF_NAT_MANIP_DST)
 658                 ct->status |= IPS_DST_NAT_DONE;
 659         else
 660                 ct->status |= IPS_SRC_NAT_DONE;
 661
 662         return NF_ACCEPT;
 663 }
 664 EXPORT_SYMBOL(nf_nat_setup_info);
 665
 666 static unsigned int
 667 __nf_nat_alloc_null_binding(struct nf_conn *ct, enum nf_nat_manip_type manip)
 668 {
 669         /* Force range to this IP; let proto decide mapping for
 670          * per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
 671          * Use reply in case it's already been mangled (eg local packet).
 672          */
 673         union nf_inet_addr ip =
 674                 (manip == NF_NAT_MANIP_SRC ?
 675                 ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3 :
 676                 ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3);
 677         struct nf_nat_range2 range = {
 678                 .flags          = NF_NAT_RANGE_MAP_IPS,
 679                 .min_addr       = ip,
 680                 .max_addr       = ip,
 681         };
 682         return nf_nat_setup_info(ct, &range, manip);
 683 }
 684
 685 unsigned int
 686 nf_nat_alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
 687 {
 688         return __nf_nat_alloc_null_binding(ct, HOOK2MANIP(hooknum));
 689 }
 690 EXPORT_SYMBOL_GPL(nf_nat_alloc_null_binding);
 691
 692 /* Do packet manipulations according to nf_nat_setup_info. */
 693 unsigned int nf_nat_packet(struct nf_conn *ct,
 694                            enum ip_conntrack_info ctinfo,
 695                            unsigned int hooknum,
 696                            struct sk_buff *skb)
 697 {
 698         enum nf_nat_manip_type mtype = HOOK2MANIP(hooknum);
 699         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 700         unsigned int verdict = NF_ACCEPT;
 701         unsigned long statusbit;
 702
 703         if (mtype == NF_NAT_MANIP_SRC)
 704                 statusbit = IPS_SRC_NAT;
 705         else
 706                 statusbit = IPS_DST_NAT;
 707
 708         /* Invert if this is reply dir. */
 709         if (dir == IP_CT_DIR_REPLY)
 710                 statusbit ^= IPS_NAT_MASK;
 711
 712         /* Non-atomic: these bits don't change. */
 713         if (ct->status & statusbit)
 714                 verdict = nf_nat_manip_pkt(skb, ct, mtype, dir);
 715
 716         return verdict;
 717 }
 718 EXPORT_SYMBOL_GPL(nf_nat_packet);
 719
 720 unsigned int
 721 nf_nat_inet_fn(void *priv, struct sk_buff *skb,
 722                const struct nf_hook_state *state)
 723 {
 724         struct nf_conn *ct;
 725         enum ip_conntrack_info ctinfo;
 726         struct nf_conn_nat *nat;
 727         /* maniptype == SRC for postrouting. */
 728         enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook);
 729
 730         ct = nf_ct_get(skb, &ctinfo);
 731         /* Can't track?  It's not due to stress, or conntrack would
 732          * have dropped it.  Hence it's the user's responsibilty to
 733          * packet filter it out, or implement conntrack/NAT for that
 734          * protocol. 8) --RR
 735          */
 736         if (!ct)
 737                 return NF_ACCEPT;
 738
 739         nat = nfct_nat(ct);
 740
 741         switch (ctinfo) {
 742         case IP_CT_RELATED:
 743         case IP_CT_RELATED_REPLY:
 744                 /* Only ICMPs can be IP_CT_IS_REPLY.  Fallthrough */
 745         case IP_CT_NEW:
 746                 /* Seen it before?  This can happen for loopback, retrans,
 747                  * or local packets.
 748                  */
 749                 if (!nf_nat_initialized(ct, maniptype)) {
 750                         struct nf_nat_lookup_hook_priv *lpriv = priv;
 751                         struct nf_hook_entries *e = rcu_dereference(lpriv->entries);
 752                         unsigned int ret;
 753                         int i;
 754
 755                         if (!e)
 756                                 goto null_bind;
 757
 758                         for (i = 0; i < e->num_hook_entries; i++) {
 759                                 ret = e->hooks[i].hook(e->hooks[i].priv, skb,
 760                                                        state);
 761                                 if (ret != NF_ACCEPT)
 762                                         return ret;
 763                                 if (nf_nat_initialized(ct, maniptype))
 764                                         goto do_nat;
 765                         }
 766 null_bind:
 767                         ret = nf_nat_alloc_null_binding(ct, state->hook);
 768                         if (ret != NF_ACCEPT)
 769                                 return ret;
 770                 } else {
 771                         pr_debug("Already setup manip %s for ct %p (status bits 0x%lx)\n",
 772                                  maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
 773                                  ct, ct->status);
 774                         if (nf_nat_oif_changed(state->hook, ctinfo, nat,
 775                                                state->out))
 776                                 goto oif_changed;
 777                 }
 778                 break;
 779         default:
 780                 /* ESTABLISHED */
 781                 WARN_ON(ctinfo != IP_CT_ESTABLISHED &&
 782                         ctinfo != IP_CT_ESTABLISHED_REPLY);
 783                 if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
 784                         goto oif_changed;
 785         }
 786 do_nat:
 787         return nf_nat_packet(ct, ctinfo, state->hook, skb);
 788
 789 oif_changed:
 790         nf_ct_kill_acct(ct, ctinfo, skb);
 791         return NF_DROP;
 792 }
 793 EXPORT_SYMBOL_GPL(nf_nat_inet_fn);
 794
 795 struct nf_nat_proto_clean {
 796         u8      l3proto;
 797         u8      l4proto;
 798 };
 799
 800 /* kill conntracks with affected NAT section */
 801 static int nf_nat_proto_remove(struct nf_conn *i, void *data)
 802 {
 803         const struct nf_nat_proto_clean *clean = data;
 804
 805         if ((clean->l3proto && nf_ct_l3num(i) != clean->l3proto) ||
 806             (clean->l4proto && nf_ct_protonum(i) != clean->l4proto))
 807                 return 0;
 808
 809         return i->status & IPS_NAT_MASK ? 1 : 0;
 810 }
 811
 812 static void __nf_nat_cleanup_conntrack(struct nf_conn *ct)
 813 {
 814         unsigned int h;
 815
 816         h = hash_by_src(nf_ct_net(ct), &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
 817         spin_lock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]);
 818         hlist_del_rcu(&ct->nat_bysource);
 819         spin_unlock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]);
 820 }
 821
 822 static int nf_nat_proto_clean(struct nf_conn *ct, void *data)
 823 {
 824         if (nf_nat_proto_remove(ct, data))
 825                 return 1;
 826
 827         /* This module is being removed and conntrack has nat null binding.
 828          * Remove it from bysource hash, as the table will be freed soon.
 829          *
 830          * Else, when the conntrack is destoyed, nf_nat_cleanup_conntrack()
 831          * will delete entry from already-freed table.
 832          */
 833         if (test_and_clear_bit(IPS_SRC_NAT_DONE_BIT, &ct->status))
 834                 __nf_nat_cleanup_conntrack(ct);
 835
 836         /* don't delete conntrack.  Although that would make things a lot
 837          * simpler, we'd end up flushing all conntracks on nat rmmod.
 838          */
 839         return 0;
 840 }
 841
 842 /* No one using conntrack by the time this called. */
 843 static void nf_nat_cleanup_conntrack(struct nf_conn *ct)
 844 {
 845         if (ct->status & IPS_SRC_NAT_DONE)
 846                 __nf_nat_cleanup_conntrack(ct);
 847 }
 848
 849 static struct nf_ct_ext_type nat_extend __read_mostly = {
 850         .len            = sizeof(struct nf_conn_nat),
 851         .align          = __alignof__(struct nf_conn_nat),
 852         .destroy        = nf_nat_cleanup_conntrack,
 853         .id             = NF_CT_EXT_NAT,
 854 };
 855
 856 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 857
 858 #include <linux/netfilter/nfnetlink.h>
 859 #include <linux/netfilter/nfnetlink_conntrack.h>
 860
 861 static const struct nla_policy protonat_nla_policy[CTA_PROTONAT_MAX+1] = {
 862         [CTA_PROTONAT_PORT_MIN] = { .type = NLA_U16 },
 863         [CTA_PROTONAT_PORT_MAX] = { .type = NLA_U16 },
 864 };
 865
 866 static int nf_nat_l4proto_nlattr_to_range(struct nlattr *tb[],
 867                                           struct nf_nat_range2 *range)
 868 {
 869         if (tb[CTA_PROTONAT_PORT_MIN]) {
 870                 range->min_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MIN]);
 871                 range->max_proto.all = range->min_proto.all;
 872                 range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
 873         }
 874         if (tb[CTA_PROTONAT_PORT_MAX]) {
 875                 range->max_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MAX]);
 876                 range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
 877         }
 878         return 0;
 879 }
 880
 881 static int nfnetlink_parse_nat_proto(struct nlattr *attr,
 882                                      const struct nf_conn *ct,
 883                                      struct nf_nat_range2 *range)
 884 {
 885         struct nlattr *tb[CTA_PROTONAT_MAX+1];
 886         int err;
 887
 888         err = nla_parse_nested(tb, CTA_PROTONAT_MAX, attr,
 889                                protonat_nla_policy, NULL);
 890         if (err < 0)
 891                 return err;
 892
 893         return nf_nat_l4proto_nlattr_to_range(tb, range);
 894 }
 895
 896 static const struct nla_policy nat_nla_policy[CTA_NAT_MAX+1] = {
 897         [CTA_NAT_V4_MINIP]      = { .type = NLA_U32 },
 898         [CTA_NAT_V4_MAXIP]      = { .type = NLA_U32 },
 899         [CTA_NAT_V6_MINIP]      = { .len = sizeof(struct in6_addr) },
 900         [CTA_NAT_V6_MAXIP]      = { .len = sizeof(struct in6_addr) },
 901         [CTA_NAT_PROTO]         = { .type = NLA_NESTED },
 902 };
 903
 904 static int nf_nat_ipv4_nlattr_to_range(struct nlattr *tb[],
 905                                        struct nf_nat_range2 *range)
 906 {
 907         if (tb[CTA_NAT_V4_MINIP]) {
 908                 range->min_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MINIP]);
 909                 range->flags |= NF_NAT_RANGE_MAP_IPS;
 910         }
 911
 912         if (tb[CTA_NAT_V4_MAXIP])
 913                 range->max_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MAXIP]);
 914         else
 915                 range->max_addr.ip = range->min_addr.ip;
 916
 917         return 0;
 918 }
 919
 920 static int nf_nat_ipv6_nlattr_to_range(struct nlattr *tb[],
 921                                        struct nf_nat_range2 *range)
 922 {
 923         if (tb[CTA_NAT_V6_MINIP]) {
 924                 nla_memcpy(&range->min_addr.ip6, tb[CTA_NAT_V6_MINIP],
 925                            sizeof(struct in6_addr));
 926                 range->flags |= NF_NAT_RANGE_MAP_IPS;
 927         }
 928
 929         if (tb[CTA_NAT_V6_MAXIP])
 930                 nla_memcpy(&range->max_addr.ip6, tb[CTA_NAT_V6_MAXIP],
 931                            sizeof(struct in6_addr));
 932         else
 933                 range->max_addr = range->min_addr;
 934
 935         return 0;
 936 }
 937
 938 static int
 939 nfnetlink_parse_nat(const struct nlattr *nat,
 940                     const struct nf_conn *ct, struct nf_nat_range2 *range)
 941 {
 942         struct nlattr *tb[CTA_NAT_MAX+1];
 943         int err;
 944
 945         memset(range, 0, sizeof(*range));
 946
 947         err = nla_parse_nested(tb, CTA_NAT_MAX, nat, nat_nla_policy, NULL);
 948         if (err < 0)
 949                 return err;
 950
 951         switch (nf_ct_l3num(ct)) {
 952         case NFPROTO_IPV4:
 953                 err = nf_nat_ipv4_nlattr_to_range(tb, range);
 954                 break;
 955         case NFPROTO_IPV6:
 956                 err = nf_nat_ipv6_nlattr_to_range(tb, range);
 957                 break;
 958         default:
 959                 err = -EPROTONOSUPPORT;
 960                 break;
 961         }
 962
 963         if (err)
 964                 return err;
 965
 966         if (!tb[CTA_NAT_PROTO])
 967                 return 0;
 968
 969         return nfnetlink_parse_nat_proto(tb[CTA_NAT_PROTO], ct, range);
 970 }
 971
 972 /* This function is called under rcu_read_lock() */
 973 static int
 974 nfnetlink_parse_nat_setup(struct nf_conn *ct,
 975                           enum nf_nat_manip_type manip,
 976                           const struct nlattr *attr)
 977 {
 978         struct nf_nat_range2 range;
 979         int err;
 980
 981         /* Should not happen, restricted to creating new conntracks
 982          * via ctnetlink.
 983          */
 984         if (WARN_ON_ONCE(nf_nat_initialized(ct, manip)))
 985                 return -EEXIST;
 986
 987         /* No NAT information has been passed, allocate the null-binding */
 988         if (attr == NULL)
 989                 return __nf_nat_alloc_null_binding(ct, manip) == NF_DROP ? -ENOMEM : 0;
 990
 991         err = nfnetlink_parse_nat(attr, ct, &range);
 992         if (err < 0)
 993                 return err;
 994
 995         return nf_nat_setup_info(ct, &range, manip) == NF_DROP ? -ENOMEM : 0;
 996 }
 997 #else
 998 static int
 999 nfnetlink_parse_nat_setup(struct nf_conn *ct,
1000                           enum nf_nat_manip_type manip,
1001                           const struct nlattr *attr)
1002 {
1003         return -EOPNOTSUPP;
1004 }
1005 #endif
1006
1007 static struct nf_ct_helper_expectfn follow_master_nat = {
1008         .name           = "nat-follow-master",
1009         .expectfn       = nf_nat_follow_master,
1010 };
1011
1012 int nf_nat_register_fn(struct net *net, const struct nf_hook_ops *ops,
1013                        const struct nf_hook_ops *orig_nat_ops, unsigned int ops_count)
1014 {
1015         struct nat_net *nat_net = net_generic(net, nat_net_id);
1016         struct nf_nat_hooks_net *nat_proto_net;
1017         struct nf_nat_lookup_hook_priv *priv;
1018         unsigned int hooknum = ops->hooknum;
1019         struct nf_hook_ops *nat_ops;
1020         int i, ret;
1021
1022         if (WARN_ON_ONCE(ops->pf >= ARRAY_SIZE(nat_net->nat_proto_net)))
1023                 return -EINVAL;
1024
1025         nat_proto_net = &nat_net->nat_proto_net[ops->pf];
1026
1027         for (i = 0; i < ops_count; i++) {
1028                 if (WARN_ON(orig_nat_ops[i].pf != ops->pf))
1029                         return -EINVAL;
1030                 if (orig_nat_ops[i].hooknum == hooknum) {
1031                         hooknum = i;
1032                         break;
1033                 }
1034         }
1035
1036         if (WARN_ON_ONCE(i == ops_count))
1037                 return -EINVAL;
1038
1039         mutex_lock(&nf_nat_proto_mutex);
1040         if (!nat_proto_net->nat_hook_ops) {
1041                 WARN_ON(nat_proto_net->users != 0);
1042
1043                 nat_ops = kmemdup(orig_nat_ops, sizeof(*orig_nat_ops) * ops_count, GFP_KERNEL);
1044                 if (!nat_ops) {
1045                         mutex_unlock(&nf_nat_proto_mutex);
1046                         return -ENOMEM;
1047                 }
1048
1049                 for (i = 0; i < ops_count; i++) {
1050                         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
1051                         if (priv) {
1052                                 nat_ops[i].priv = priv;
1053                                 continue;
1054                         }
1055                         mutex_unlock(&nf_nat_proto_mutex);
1056                         while (i)
1057                                 kfree(nat_ops[--i].priv);
1058                         kfree(nat_ops);
1059                         return -ENOMEM;
1060                 }
1061
1062                 ret = nf_register_net_hooks(net, nat_ops, ops_count);
1063                 if (ret < 0) {
1064                         mutex_unlock(&nf_nat_proto_mutex);
1065                         for (i = 0; i < ops_count; i++)
1066                                 kfree(nat_ops[i].priv);
1067                         kfree(nat_ops);
1068                         return ret;
1069                 }
1070
1071                 nat_proto_net->nat_hook_ops = nat_ops;
1072         }
1073
1074         nat_ops = nat_proto_net->nat_hook_ops;
1075         priv = nat_ops[hooknum].priv;
1076         if (WARN_ON_ONCE(!priv)) {
1077                 mutex_unlock(&nf_nat_proto_mutex);
1078                 return -EOPNOTSUPP;
1079         }
1080
1081         ret = nf_hook_entries_insert_raw(&priv->entries, ops);
1082         if (ret == 0)
1083                 nat_proto_net->users++;
1084
1085         mutex_unlock(&nf_nat_proto_mutex);
1086         return ret;
1087 }
1088
1089 void nf_nat_unregister_fn(struct net *net, const struct nf_hook_ops *ops,
1090                           unsigned int ops_count)
1091 {
1092         struct nat_net *nat_net = net_generic(net, nat_net_id);
1093         struct nf_nat_hooks_net *nat_proto_net;
1094         struct nf_nat_lookup_hook_priv *priv;
1095         struct nf_hook_ops *nat_ops;
1096         int hooknum = ops->hooknum;
1097         int i;
1098
1099         if (ops->pf >= ARRAY_SIZE(nat_net->nat_proto_net))
1100                 return;
1101
1102         nat_proto_net = &nat_net->nat_proto_net[ops->pf];
1103
1104         mutex_lock(&nf_nat_proto_mutex);
1105         if (WARN_ON(nat_proto_net->users == 0))
1106                 goto unlock;
1107
1108         nat_proto_net->users--;
1109
1110         nat_ops = nat_proto_net->nat_hook_ops;
1111         for (i = 0; i < ops_count; i++) {
1112                 if (nat_ops[i].hooknum == hooknum) {
1113                         hooknum = i;
1114                         break;
1115                 }
1116         }
1117         if (WARN_ON_ONCE(i == ops_count))
1118                 goto unlock;
1119         priv = nat_ops[hooknum].priv;
1120         nf_hook_entries_delete_raw(&priv->entries, ops);
1121
1122         if (nat_proto_net->users == 0) {
1123                 nf_unregister_net_hooks(net, nat_ops, ops_count);
1124
1125                 for (i = 0; i < ops_count; i++) {
1126                         priv = nat_ops[i].priv;
1127                         kfree_rcu(priv, rcu_head);
1128                 }
1129
1130                 nat_proto_net->nat_hook_ops = NULL;
1131                 kfree(nat_ops);
1132         }
1133 unlock:
1134         mutex_unlock(&nf_nat_proto_mutex);
1135 }
1136
1137 static struct pernet_operations nat_net_ops = {
1138         .id = &nat_net_id,
1139         .size = sizeof(struct nat_net),
1140 };
1141
1142 static struct nf_nat_hook nat_hook = {
1143         .parse_nat_setup        = nfnetlink_parse_nat_setup,
1144 #ifdef CONFIG_XFRM
1145         .decode_session         = __nf_nat_decode_session,
1146 #endif
1147         .manip_pkt              = nf_nat_manip_pkt,
1148 };
1149
1150 static int __init nf_nat_init(void)
1151 {
1152         int ret, i;
1153
1154         /* Leave them the same for the moment. */
1155         nf_nat_htable_size = nf_conntrack_htable_size;
1156         if (nf_nat_htable_size < CONNTRACK_LOCKS)
1157                 nf_nat_htable_size = CONNTRACK_LOCKS;
1158
1159         nf_nat_bysource = nf_ct_alloc_hashtable(&nf_nat_htable_size, 0);
1160         if (!nf_nat_bysource)
1161                 return -ENOMEM;
1162
1163         ret = nf_ct_extend_register(&nat_extend);
1164         if (ret < 0) {
1165                 kvfree(nf_nat_bysource);
1166                 pr_err("Unable to register extension\n");
1167                 return ret;
1168         }
1169
1170         for (i = 0; i < CONNTRACK_LOCKS; i++)
1171                 spin_lock_init(&nf_nat_locks[i]);
1172
1173         ret = register_pernet_subsys(&nat_net_ops);
1174         if (ret < 0) {
1175                 nf_ct_extend_unregister(&nat_extend);
1176                 return ret;
1177         }
1178
1179         nf_ct_helper_expectfn_register(&follow_master_nat);
1180
1181         WARN_ON(nf_nat_hook != NULL);
1182         RCU_INIT_POINTER(nf_nat_hook, &nat_hook);
1183
1184         return 0;
1185 }
1186
1187 static void __exit nf_nat_cleanup(void)
1188 {
1189         struct nf_nat_proto_clean clean = {};
1190
1191         nf_ct_iterate_destroy(nf_nat_proto_clean, &clean);
1192
1193         nf_ct_extend_unregister(&nat_extend);
1194         nf_ct_helper_expectfn_unregister(&follow_master_nat);
1195         RCU_INIT_POINTER(nf_nat_hook, NULL);
1196
1197         synchronize_net();
1198         kvfree(nf_nat_bysource);
1199         unregister_pernet_subsys(&nat_net_ops);
1200 }
1201
1202 MODULE_LICENSE("GPL");
1203
1204 module_init(nf_nat_init);
1205 module_exit(nf_nat_cleanup);