net/netfilter/nf_nat_core.c

   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/jhash.h>
  17 #include <linux/rtnetlink.h>
  18
  19 #include <net/netfilter/nf_conntrack.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 static spinlock_t nf_nat_locks[CONNTRACK_LOCKS];
  31
  32 static DEFINE_MUTEX(nf_nat_proto_mutex);
  33 static unsigned int nat_net_id __read_mostly;
  34
  35 static struct hlist_head *nf_nat_bysource __read_mostly;
  36 static unsigned int nf_nat_htable_size __read_mostly;
  37 static unsigned int nf_nat_hash_rnd __read_mostly;
  38
  39 struct nf_nat_lookup_hook_priv {
  40         struct nf_hook_entries __rcu *entries;
  41
  42         struct rcu_head rcu_head;
  43 };
  44
  45 struct nf_nat_hooks_net {
  46         struct nf_hook_ops *nat_hook_ops;
  47         unsigned int users;
  48 };
  49
  50 struct nat_net {
  51         struct nf_nat_hooks_net nat_proto_net[NFPROTO_NUMPROTO];
  52 };
  53
  54 #ifdef CONFIG_XFRM
  55 static void nf_nat_ipv4_decode_session(struct sk_buff *skb,
  56                                        const struct nf_conn *ct,
  57                                        enum ip_conntrack_dir dir,
  58                                        unsigned long statusbit,
  59                                        struct flowi *fl)
  60 {
  61         const struct nf_conntrack_tuple *t = &ct->tuplehash[dir].tuple;
  62         struct flowi4 *fl4 = &fl->u.ip4;
  63
  64         if (ct->status & statusbit) {
  65                 fl4->daddr = t->dst.u3.ip;
  66                 if (t->dst.protonum == IPPROTO_TCP ||
  67                     t->dst.protonum == IPPROTO_UDP ||
  68                     t->dst.protonum == IPPROTO_UDPLITE ||
  69                     t->dst.protonum == IPPROTO_DCCP ||
  70                     t->dst.protonum == IPPROTO_SCTP)
  71                         fl4->fl4_dport = t->dst.u.all;
  72         }
  73
  74         statusbit ^= IPS_NAT_MASK;
  75
  76         if (ct->status & statusbit) {
  77                 fl4->saddr = t->src.u3.ip;
  78                 if (t->dst.protonum == IPPROTO_TCP ||
  79                     t->dst.protonum == IPPROTO_UDP ||
  80                     t->dst.protonum == IPPROTO_UDPLITE ||
  81                     t->dst.protonum == IPPROTO_DCCP ||
  82                     t->dst.protonum == IPPROTO_SCTP)
  83                         fl4->fl4_sport = t->src.u.all;
  84         }
  85 }
  86
  87 static void nf_nat_ipv6_decode_session(struct sk_buff *skb,
  88                                        const struct nf_conn *ct,
  89                                        enum ip_conntrack_dir dir,
  90                                        unsigned long statusbit,
  91                                        struct flowi *fl)
  92 {
  93 #if IS_ENABLED(CONFIG_IPV6)
  94         const struct nf_conntrack_tuple *t = &ct->tuplehash[dir].tuple;
  95         struct flowi6 *fl6 = &fl->u.ip6;
  96
  97         if (ct->status & statusbit) {
  98                 fl6->daddr = t->dst.u3.in6;
  99                 if (t->dst.protonum == IPPROTO_TCP ||
 100                     t->dst.protonum == IPPROTO_UDP ||
 101                     t->dst.protonum == IPPROTO_UDPLITE ||
 102                     t->dst.protonum == IPPROTO_DCCP ||
 103                     t->dst.protonum == IPPROTO_SCTP)
 104                         fl6->fl6_dport = t->dst.u.all;
 105         }
 106
 107         statusbit ^= IPS_NAT_MASK;
 108
 109         if (ct->status & statusbit) {
 110                 fl6->saddr = t->src.u3.in6;
 111                 if (t->dst.protonum == IPPROTO_TCP ||
 112                     t->dst.protonum == IPPROTO_UDP ||
 113                     t->dst.protonum == IPPROTO_UDPLITE ||
 114                     t->dst.protonum == IPPROTO_DCCP ||
 115                     t->dst.protonum == IPPROTO_SCTP)
 116                         fl6->fl6_sport = t->src.u.all;
 117         }
 118 #endif
 119 }
 120
 121 static void __nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl)
 122 {
 123         const struct nf_conn *ct;
 124         enum ip_conntrack_info ctinfo;
 125         enum ip_conntrack_dir dir;
 126         unsigned  long statusbit;
 127         u8 family;
 128
 129         ct = nf_ct_get(skb, &ctinfo);
 130         if (ct == NULL)
 131                 return;
 132
 133         family = nf_ct_l3num(ct);
 134         dir = CTINFO2DIR(ctinfo);
 135         if (dir == IP_CT_DIR_ORIGINAL)
 136                 statusbit = IPS_DST_NAT;
 137         else
 138                 statusbit = IPS_SRC_NAT;
 139
 140         switch (family) {
 141         case NFPROTO_IPV4:
 142                 nf_nat_ipv4_decode_session(skb, ct, dir, statusbit, fl);
 143                 return;
 144         case NFPROTO_IPV6:
 145                 nf_nat_ipv6_decode_session(skb, ct, dir, statusbit, fl);
 146                 return;
 147         }
 148 }
 149
 150 int nf_xfrm_me_harder(struct net *net, struct sk_buff *skb, unsigned int family)
 151 {
 152         struct flowi fl;
 153         unsigned int hh_len;
 154         struct dst_entry *dst;
 155         struct sock *sk = skb->sk;
 156         int err;
 157
 158         err = xfrm_decode_session(skb, &fl, family);
 159         if (err < 0)
 160                 return err;
 161
 162         dst = skb_dst(skb);
 163         if (dst->xfrm)
 164                 dst = ((struct xfrm_dst *)dst)->route;
 165         if (!dst_hold_safe(dst))
 166                 return -EHOSTUNREACH;
 167
 168         if (sk && !net_eq(net, sock_net(sk)))
 169                 sk = NULL;
 170
 171         dst = xfrm_lookup(net, dst, &fl, sk, 0);
 172         if (IS_ERR(dst))
 173                 return PTR_ERR(dst);
 174
 175         skb_dst_drop(skb);
 176         skb_dst_set(skb, dst);
 177
 178         /* Change in oif may mean change in hh_len. */
 179         hh_len = skb_dst(skb)->dev->hard_header_len;
 180         if (skb_headroom(skb) < hh_len &&
 181             pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
 182                 return -ENOMEM;
 183         return 0;
 184 }
 185 EXPORT_SYMBOL(nf_xfrm_me_harder);
 186 #endif /* CONFIG_XFRM */
 187
 188 /* We keep an extra hash for each conntrack, for fast searching. */
 189 static unsigned int
 190 hash_by_src(const struct net *n, const struct nf_conntrack_tuple *tuple)
 191 {
 192         unsigned int hash;
 193
 194         get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd));
 195
 196         /* Original src, to ensure we map it consistently if poss. */
 197         hash = jhash2((u32 *)&tuple->src, sizeof(tuple->src) / sizeof(u32),
 198                       tuple->dst.protonum ^ nf_nat_hash_rnd ^ net_hash_mix(n));
 199
 200         return reciprocal_scale(hash, nf_nat_htable_size);
 201 }
 202
 203 /* Is this tuple already taken? (not by us) */
 204 static int
 205 nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple,
 206                   const struct nf_conn *ignored_conntrack)
 207 {
 208         /* Conntrack tracking doesn't keep track of outgoing tuples; only
 209          * incoming ones.  NAT means they don't have a fixed mapping,
 210          * so we invert the tuple and look for the incoming reply.
 211          *
 212          * We could keep a separate hash if this proves too slow.
 213          */
 214         struct nf_conntrack_tuple reply;
 215
 216         nf_ct_invert_tuple(&reply, tuple);
 217         return nf_conntrack_tuple_taken(&reply, ignored_conntrack);
 218 }
 219
 220 static bool nf_nat_inet_in_range(const struct nf_conntrack_tuple *t,
 221                                  const struct nf_nat_range2 *range)
 222 {
 223         if (t->src.l3num == NFPROTO_IPV4)
 224                 return ntohl(t->src.u3.ip) >= ntohl(range->min_addr.ip) &&
 225                        ntohl(t->src.u3.ip) <= ntohl(range->max_addr.ip);
 226
 227         return ipv6_addr_cmp(&t->src.u3.in6, &range->min_addr.in6) >= 0 &&
 228                ipv6_addr_cmp(&t->src.u3.in6, &range->max_addr.in6) <= 0;
 229 }
 230
 231 /* Is the manipable part of the tuple between min and max incl? */
 232 static bool l4proto_in_range(const struct nf_conntrack_tuple *tuple,
 233                              enum nf_nat_manip_type maniptype,
 234                              const union nf_conntrack_man_proto *min,
 235                              const union nf_conntrack_man_proto *max)
 236 {
 237         __be16 port;
 238
 239         switch (tuple->dst.protonum) {
 240         case IPPROTO_ICMP:
 241         case IPPROTO_ICMPV6:
 242                 return ntohs(tuple->src.u.icmp.id) >= ntohs(min->icmp.id) &&
 243                        ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id);
 244         case IPPROTO_GRE: /* all fall though */
 245         case IPPROTO_TCP:
 246         case IPPROTO_UDP:
 247         case IPPROTO_UDPLITE:
 248         case IPPROTO_DCCP:
 249         case IPPROTO_SCTP:
 250                 if (maniptype == NF_NAT_MANIP_SRC)
 251                         port = tuple->src.u.all;
 252                 else
 253                         port = tuple->dst.u.all;
 254
 255                 return ntohs(port) >= ntohs(min->all) &&
 256                        ntohs(port) <= ntohs(max->all);
 257         default:
 258                 return true;
 259         }
 260 }
 261
 262 /* If we source map this tuple so reply looks like reply_tuple, will
 263  * that meet the constraints of range.
 264  */
 265 static int in_range(const struct nf_conntrack_tuple *tuple,
 266                     const struct nf_nat_range2 *range)
 267 {
 268         /* If we are supposed to map IPs, then we must be in the
 269          * range specified, otherwise let this drag us onto a new src IP.
 270          */
 271         if (range->flags & NF_NAT_RANGE_MAP_IPS &&
 272             !nf_nat_inet_in_range(tuple, range))
 273                 return 0;
 274
 275         if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED))
 276                 return 1;
 277
 278         return l4proto_in_range(tuple, NF_NAT_MANIP_SRC,
 279                                 &range->min_proto, &range->max_proto);
 280 }
 281
 282 static inline int
 283 same_src(const struct nf_conn *ct,
 284          const struct nf_conntrack_tuple *tuple)
 285 {
 286         const struct nf_conntrack_tuple *t;
 287
 288         t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
 289         return (t->dst.protonum == tuple->dst.protonum &&
 290                 nf_inet_addr_cmp(&t->src.u3, &tuple->src.u3) &&
 291                 t->src.u.all == tuple->src.u.all);
 292 }
 293
 294 /* Only called for SRC manip */
 295 static int
 296 find_appropriate_src(struct net *net,
 297                      const struct nf_conntrack_zone *zone,
 298                      const struct nf_conntrack_tuple *tuple,
 299                      struct nf_conntrack_tuple *result,
 300                      const struct nf_nat_range2 *range)
 301 {
 302         unsigned int h = hash_by_src(net, tuple);
 303         const struct nf_conn *ct;
 304
 305         hlist_for_each_entry_rcu(ct, &nf_nat_bysource[h], nat_bysource) {
 306                 if (same_src(ct, tuple) &&
 307                     net_eq(net, nf_ct_net(ct)) &&
 308                     nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL)) {
 309                         /* Copy source part from reply tuple. */
 310                         nf_ct_invert_tuple(result,
 311                                        &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
 312                         result->dst = tuple->dst;
 313
 314                         if (in_range(result, range))
 315                                 return 1;
 316                 }
 317         }
 318         return 0;
 319 }
 320
 321 /* For [FUTURE] fragmentation handling, we want the least-used
 322  * src-ip/dst-ip/proto triple.  Fairness doesn't come into it.  Thus
 323  * if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports
 324  * 1-65535, we don't do pro-rata allocation based on ports; we choose
 325  * the ip with the lowest src-ip/dst-ip/proto usage.
 326  */
 327 static void
 328 find_best_ips_proto(const struct nf_conntrack_zone *zone,
 329                     struct nf_conntrack_tuple *tuple,
 330                     const struct nf_nat_range2 *range,
 331                     const struct nf_conn *ct,
 332                     enum nf_nat_manip_type maniptype)
 333 {
 334         union nf_inet_addr *var_ipp;
 335         unsigned int i, max;
 336         /* Host order */
 337         u32 minip, maxip, j, dist;
 338         bool full_range;
 339
 340         /* No IP mapping?  Do nothing. */
 341         if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
 342                 return;
 343
 344         if (maniptype == NF_NAT_MANIP_SRC)
 345                 var_ipp = &tuple->src.u3;
 346         else
 347                 var_ipp = &tuple->dst.u3;
 348
 349         /* Fast path: only one choice. */
 350         if (nf_inet_addr_cmp(&range->min_addr, &range->max_addr)) {
 351                 *var_ipp = range->min_addr;
 352                 return;
 353         }
 354
 355         if (nf_ct_l3num(ct) == NFPROTO_IPV4)
 356                 max = sizeof(var_ipp->ip) / sizeof(u32) - 1;
 357         else
 358                 max = sizeof(var_ipp->ip6) / sizeof(u32) - 1;
 359
 360         /* Hashing source and destination IPs gives a fairly even
 361          * spread in practice (if there are a small number of IPs
 362          * involved, there usually aren't that many connections
 363          * anyway).  The consistency means that servers see the same
 364          * client coming from the same IP (some Internet Banking sites
 365          * like this), even across reboots.
 366          */
 367         j = jhash2((u32 *)&tuple->src.u3, sizeof(tuple->src.u3) / sizeof(u32),
 368                    range->flags & NF_NAT_RANGE_PERSISTENT ?
 369                         0 : (__force u32)tuple->dst.u3.all[max] ^ zone->id);
 370
 371         full_range = false;
 372         for (i = 0; i <= max; i++) {
 373                 /* If first bytes of the address are at the maximum, use the
 374                  * distance. Otherwise use the full range.
 375                  */
 376                 if (!full_range) {
 377                         minip = ntohl((__force __be32)range->min_addr.all[i]);
 378                         maxip = ntohl((__force __be32)range->max_addr.all[i]);
 379                         dist  = maxip - minip + 1;
 380                 } else {
 381                         minip = 0;
 382                         dist  = ~0;
 383                 }
 384
 385                 var_ipp->all[i] = (__force __u32)
 386                         htonl(minip + reciprocal_scale(j, dist));
 387                 if (var_ipp->all[i] != range->max_addr.all[i])
 388                         full_range = true;
 389
 390                 if (!(range->flags & NF_NAT_RANGE_PERSISTENT))
 391                         j ^= (__force u32)tuple->dst.u3.all[i];
 392         }
 393 }
 394
 395 /* Alter the per-proto part of the tuple (depending on maniptype), to
 396  * give a unique tuple in the given range if possible.
 397  *
 398  * Per-protocol part of tuple is initialized to the incoming packet.
 399  */
 400 static void nf_nat_l4proto_unique_tuple(struct nf_conntrack_tuple *tuple,
 401                                         const struct nf_nat_range2 *range,
 402                                         enum nf_nat_manip_type maniptype,
 403                                         const struct nf_conn *ct)
 404 {
 405         unsigned int range_size, min, max, i, attempts;
 406         __be16 *keyptr;
 407         u16 off;
 408         static const unsigned int max_attempts = 128;
 409
 410         switch (tuple->dst.protonum) {
 411         case IPPROTO_ICMP:
 412         case IPPROTO_ICMPV6:
 413                 /* id is same for either direction... */
 414                 keyptr = &tuple->src.u.icmp.id;
 415                 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
 416                         min = 0;
 417                         range_size = 65536;
 418                 } else {
 419                         min = ntohs(range->min_proto.icmp.id);
 420                         range_size = ntohs(range->max_proto.icmp.id) -
 421                                      ntohs(range->min_proto.icmp.id) + 1;
 422                 }
 423                 goto find_free_id;
 424 #if IS_ENABLED(CONFIG_NF_CT_PROTO_GRE)
 425         case IPPROTO_GRE:
 426                 /* If there is no master conntrack we are not PPTP,
 427                    do not change tuples */
 428                 if (!ct->master)
 429                         return;
 430
 431                 if (maniptype == NF_NAT_MANIP_SRC)
 432                         keyptr = &tuple->src.u.gre.key;
 433                 else
 434                         keyptr = &tuple->dst.u.gre.key;
 435
 436                 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
 437                         min = 1;
 438                         range_size = 65535;
 439                 } else {
 440                         min = ntohs(range->min_proto.gre.key);
 441                         range_size = ntohs(range->max_proto.gre.key) - min + 1;
 442                 }
 443                 goto find_free_id;
 444 #endif
 445         case IPPROTO_UDP:
 446         case IPPROTO_UDPLITE:
 447         case IPPROTO_TCP:
 448         case IPPROTO_SCTP:
 449         case IPPROTO_DCCP:
 450                 if (maniptype == NF_NAT_MANIP_SRC)
 451                         keyptr = &tuple->src.u.all;
 452                 else
 453                         keyptr = &tuple->dst.u.all;
 454
 455                 break;
 456         default:
 457                 return;
 458         }
 459
 460         /* If no range specified... */
 461         if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
 462                 /* If it's dst rewrite, can't change port */
 463                 if (maniptype == NF_NAT_MANIP_DST)
 464                         return;
 465
 466                 if (ntohs(*keyptr) < 1024) {
 467                         /* Loose convention: >> 512 is credential passing */
 468                         if (ntohs(*keyptr) < 512) {
 469                                 min = 1;
 470                                 range_size = 511 - min + 1;
 471                         } else {
 472                                 min = 600;
 473                                 range_size = 1023 - min + 1;
 474                         }
 475                 } else {
 476                         min = 1024;
 477                         range_size = 65535 - 1024 + 1;
 478                 }
 479         } else {
 480                 min = ntohs(range->min_proto.all);
 481                 max = ntohs(range->max_proto.all);
 482                 if (unlikely(max < min))
 483                         swap(max, min);
 484                 range_size = max - min + 1;
 485         }
 486
 487 find_free_id:
 488         if (range->flags & NF_NAT_RANGE_PROTO_OFFSET)
 489                 off = (ntohs(*keyptr) - ntohs(range->base_proto.all));
 490         else
 491                 off = prandom_u32();
 492
 493         attempts = range_size;
 494         if (attempts > max_attempts)
 495                 attempts = max_attempts;
 496
 497         /* We are in softirq; doing a search of the entire range risks
 498          * soft lockup when all tuples are already used.
 499          *
 500          * If we can't find any free port from first offset, pick a new
 501          * one and try again, with ever smaller search window.
 502          */
 503 another_round:
 504         for (i = 0; i < attempts; i++, off++) {
 505                 *keyptr = htons(min + off % range_size);
 506                 if (!nf_nat_used_tuple(tuple, ct))
 507                         return;
 508         }
 509
 510         if (attempts >= range_size || attempts < 16)
 511                 return;
 512         attempts /= 2;
 513         off = prandom_u32();
 514         goto another_round;
 515 }
 516
 517 /* Manipulate the tuple into the range given. For NF_INET_POST_ROUTING,
 518  * we change the source to map into the range. For NF_INET_PRE_ROUTING
 519  * and NF_INET_LOCAL_OUT, we change the destination to map into the
 520  * range. It might not be possible to get a unique tuple, but we try.
 521  * At worst (or if we race), we will end up with a final duplicate in
 522  * __nf_conntrack_confirm and drop the packet. */
 523 static void
 524 get_unique_tuple(struct nf_conntrack_tuple *tuple,
 525                  const struct nf_conntrack_tuple *orig_tuple,
 526                  const struct nf_nat_range2 *range,
 527                  struct nf_conn *ct,
 528                  enum nf_nat_manip_type maniptype)
 529 {
 530         const struct nf_conntrack_zone *zone;
 531         struct net *net = nf_ct_net(ct);
 532
 533         zone = nf_ct_zone(ct);
 534
 535         /* 1) If this srcip/proto/src-proto-part is currently mapped,
 536          * and that same mapping gives a unique tuple within the given
 537          * range, use that.
 538          *
 539          * This is only required for source (ie. NAT/masq) mappings.
 540          * So far, we don't do local source mappings, so multiple
 541          * manips not an issue.
 542          */
 543         if (maniptype == NF_NAT_MANIP_SRC &&
 544             !(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
 545                 /* try the original tuple first */
 546                 if (in_range(orig_tuple, range)) {
 547                         if (!nf_nat_used_tuple(orig_tuple, ct)) {
 548                                 *tuple = *orig_tuple;
 549                                 return;
 550                         }
 551                 } else if (find_appropriate_src(net, zone,
 552                                                 orig_tuple, tuple, range)) {
 553                         pr_debug("get_unique_tuple: Found current src map\n");
 554                         if (!nf_nat_used_tuple(tuple, ct))
 555                                 return;
 556                 }
 557         }
 558
 559         /* 2) Select the least-used IP/proto combination in the given range */
 560         *tuple = *orig_tuple;
 561         find_best_ips_proto(zone, tuple, range, ct, maniptype);
 562
 563         /* 3) The per-protocol part of the manip is made to map into
 564          * the range to make a unique tuple.
 565          */
 566
 567         /* Only bother mapping if it's not already in range and unique */
 568         if (!(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
 569                 if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
 570                         if (!(range->flags & NF_NAT_RANGE_PROTO_OFFSET) &&
 571                             l4proto_in_range(tuple, maniptype,
 572                                   &range->min_proto,
 573                                   &range->max_proto) &&
 574                             (range->min_proto.all == range->max_proto.all ||
 575                              !nf_nat_used_tuple(tuple, ct)))
 576                                 return;
 577                 } else if (!nf_nat_used_tuple(tuple, ct)) {
 578                         return;
 579                 }
 580         }
 581
 582         /* Last chance: get protocol to try to obtain unique tuple. */
 583         nf_nat_l4proto_unique_tuple(tuple, range, maniptype, ct);
 584 }
 585
 586 struct nf_conn_nat *nf_ct_nat_ext_add(struct nf_conn *ct)
 587 {
 588         struct nf_conn_nat *nat = nfct_nat(ct);
 589         if (nat)
 590                 return nat;
 591
 592         if (!nf_ct_is_confirmed(ct))
 593                 nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
 594
 595         return nat;
 596 }
 597 EXPORT_SYMBOL_GPL(nf_ct_nat_ext_add);
 598
 599 unsigned int
 600 nf_nat_setup_info(struct nf_conn *ct,
 601                   const struct nf_nat_range2 *range,
 602                   enum nf_nat_manip_type maniptype)
 603 {
 604         struct net *net = nf_ct_net(ct);
 605         struct nf_conntrack_tuple curr_tuple, new_tuple;
 606
 607         /* Can't setup nat info for confirmed ct. */
 608         if (nf_ct_is_confirmed(ct))
 609                 return NF_ACCEPT;
 610
 611         WARN_ON(maniptype != NF_NAT_MANIP_SRC &&
 612                 maniptype != NF_NAT_MANIP_DST);
 613
 614         if (WARN_ON(nf_nat_initialized(ct, maniptype)))
 615                 return NF_DROP;
 616
 617         /* What we've got will look like inverse of reply. Normally
 618          * this is what is in the conntrack, except for prior
 619          * manipulations (future optimization: if num_manips == 0,
 620          * orig_tp = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple)
 621          */
 622         nf_ct_invert_tuple(&curr_tuple,
 623                            &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
 624
 625         get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype);
 626
 627         if (!nf_ct_tuple_equal(&new_tuple, &curr_tuple)) {
 628                 struct nf_conntrack_tuple reply;
 629
 630                 /* Alter conntrack table so will recognize replies. */
 631                 nf_ct_invert_tuple(&reply, &new_tuple);
 632                 nf_conntrack_alter_reply(ct, &reply);
 633
 634                 /* Non-atomic: we own this at the moment. */
 635                 if (maniptype == NF_NAT_MANIP_SRC)
 636                         ct->status |= IPS_SRC_NAT;
 637                 else
 638                         ct->status |= IPS_DST_NAT;
 639
 640                 if (nfct_help(ct) && !nfct_seqadj(ct))
 641                         if (!nfct_seqadj_ext_add(ct))
 642                                 return NF_DROP;
 643         }
 644
 645         if (maniptype == NF_NAT_MANIP_SRC) {
 646                 unsigned int srchash;
 647                 spinlock_t *lock;
 648
 649                 srchash = hash_by_src(net,
 650                                       &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
 651                 lock = &nf_nat_locks[srchash % CONNTRACK_LOCKS];
 652                 spin_lock_bh(lock);
 653                 hlist_add_head_rcu(&ct->nat_bysource,
 654                                    &nf_nat_bysource[srchash]);
 655                 spin_unlock_bh(lock);
 656         }
 657
 658         /* It's done. */
 659         if (maniptype == NF_NAT_MANIP_DST)
 660                 ct->status |= IPS_DST_NAT_DONE;
 661         else
 662                 ct->status |= IPS_SRC_NAT_DONE;
 663
 664         return NF_ACCEPT;
 665 }
 666 EXPORT_SYMBOL(nf_nat_setup_info);
 667
 668 static unsigned int
 669 __nf_nat_alloc_null_binding(struct nf_conn *ct, enum nf_nat_manip_type manip)
 670 {
 671         /* Force range to this IP; let proto decide mapping for
 672          * per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
 673          * Use reply in case it's already been mangled (eg local packet).
 674          */
 675         union nf_inet_addr ip =
 676                 (manip == NF_NAT_MANIP_SRC ?
 677                 ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3 :
 678                 ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3);
 679         struct nf_nat_range2 range = {
 680                 .flags          = NF_NAT_RANGE_MAP_IPS,
 681                 .min_addr       = ip,
 682                 .max_addr       = ip,
 683         };
 684         return nf_nat_setup_info(ct, &range, manip);
 685 }
 686
 687 unsigned int
 688 nf_nat_alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
 689 {
 690         return __nf_nat_alloc_null_binding(ct, HOOK2MANIP(hooknum));
 691 }
 692 EXPORT_SYMBOL_GPL(nf_nat_alloc_null_binding);
 693
 694 /* Do packet manipulations according to nf_nat_setup_info. */
 695 unsigned int nf_nat_packet(struct nf_conn *ct,
 696                            enum ip_conntrack_info ctinfo,
 697                            unsigned int hooknum,
 698                            struct sk_buff *skb)
 699 {
 700         enum nf_nat_manip_type mtype = HOOK2MANIP(hooknum);
 701         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 702         unsigned int verdict = NF_ACCEPT;
 703         unsigned long statusbit;
 704
 705         if (mtype == NF_NAT_MANIP_SRC)
 706                 statusbit = IPS_SRC_NAT;
 707         else
 708                 statusbit = IPS_DST_NAT;
 709
 710         /* Invert if this is reply dir. */
 711         if (dir == IP_CT_DIR_REPLY)
 712                 statusbit ^= IPS_NAT_MASK;
 713
 714         /* Non-atomic: these bits don't change. */
 715         if (ct->status & statusbit)
 716                 verdict = nf_nat_manip_pkt(skb, ct, mtype, dir);
 717
 718         return verdict;
 719 }
 720 EXPORT_SYMBOL_GPL(nf_nat_packet);
 721
 722 unsigned int
 723 nf_nat_inet_fn(void *priv, struct sk_buff *skb,
 724                const struct nf_hook_state *state)
 725 {
 726         struct nf_conn *ct;
 727         enum ip_conntrack_info ctinfo;
 728         struct nf_conn_nat *nat;
 729         /* maniptype == SRC for postrouting. */
 730         enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook);
 731
 732         ct = nf_ct_get(skb, &ctinfo);
 733         /* Can't track?  It's not due to stress, or conntrack would
 734          * have dropped it.  Hence it's the user's responsibilty to
 735          * packet filter it out, or implement conntrack/NAT for that
 736          * protocol. 8) --RR
 737          */
 738         if (!ct)
 739                 return NF_ACCEPT;
 740
 741         nat = nfct_nat(ct);
 742
 743         switch (ctinfo) {
 744         case IP_CT_RELATED:
 745         case IP_CT_RELATED_REPLY:
 746                 /* Only ICMPs can be IP_CT_IS_REPLY.  Fallthrough */
 747         case IP_CT_NEW:
 748                 /* Seen it before?  This can happen for loopback, retrans,
 749                  * or local packets.
 750                  */
 751                 if (!nf_nat_initialized(ct, maniptype)) {
 752                         struct nf_nat_lookup_hook_priv *lpriv = priv;
 753                         struct nf_hook_entries *e = rcu_dereference(lpriv->entries);
 754                         unsigned int ret;
 755                         int i;
 756
 757                         if (!e)
 758                                 goto null_bind;
 759
 760                         for (i = 0; i < e->num_hook_entries; i++) {
 761                                 ret = e->hooks[i].hook(e->hooks[i].priv, skb,
 762                                                        state);
 763                                 if (ret != NF_ACCEPT)
 764                                         return ret;
 765                                 if (nf_nat_initialized(ct, maniptype))
 766                                         goto do_nat;
 767                         }
 768 null_bind:
 769                         ret = nf_nat_alloc_null_binding(ct, state->hook);
 770                         if (ret != NF_ACCEPT)
 771                                 return ret;
 772                 } else {
 773                         pr_debug("Already setup manip %s for ct %p (status bits 0x%lx)\n",
 774                                  maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
 775                                  ct, ct->status);
 776                         if (nf_nat_oif_changed(state->hook, ctinfo, nat,
 777                                                state->out))
 778                                 goto oif_changed;
 779                 }
 780                 break;
 781         default:
 782                 /* ESTABLISHED */
 783                 WARN_ON(ctinfo != IP_CT_ESTABLISHED &&
 784                         ctinfo != IP_CT_ESTABLISHED_REPLY);
 785                 if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
 786                         goto oif_changed;
 787         }
 788 do_nat:
 789         return nf_nat_packet(ct, ctinfo, state->hook, skb);
 790
 791 oif_changed:
 792         nf_ct_kill_acct(ct, ctinfo, skb);
 793         return NF_DROP;
 794 }
 795 EXPORT_SYMBOL_GPL(nf_nat_inet_fn);
 796
 797 struct nf_nat_proto_clean {
 798         u8      l3proto;
 799         u8      l4proto;
 800 };
 801
 802 /* kill conntracks with affected NAT section */
 803 static int nf_nat_proto_remove(struct nf_conn *i, void *data)
 804 {
 805         const struct nf_nat_proto_clean *clean = data;
 806
 807         if ((clean->l3proto && nf_ct_l3num(i) != clean->l3proto) ||
 808             (clean->l4proto && nf_ct_protonum(i) != clean->l4proto))
 809                 return 0;
 810
 811         return i->status & IPS_NAT_MASK ? 1 : 0;
 812 }
 813
 814 static void __nf_nat_cleanup_conntrack(struct nf_conn *ct)
 815 {
 816         unsigned int h;
 817
 818         h = hash_by_src(nf_ct_net(ct), &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
 819         spin_lock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]);
 820         hlist_del_rcu(&ct->nat_bysource);
 821         spin_unlock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]);
 822 }
 823
 824 static int nf_nat_proto_clean(struct nf_conn *ct, void *data)
 825 {
 826         if (nf_nat_proto_remove(ct, data))
 827                 return 1;
 828
 829         /* This module is being removed and conntrack has nat null binding.
 830          * Remove it from bysource hash, as the table will be freed soon.
 831          *
 832          * Else, when the conntrack is destoyed, nf_nat_cleanup_conntrack()
 833          * will delete entry from already-freed table.
 834          */
 835         if (test_and_clear_bit(IPS_SRC_NAT_DONE_BIT, &ct->status))
 836                 __nf_nat_cleanup_conntrack(ct);
 837
 838         /* don't delete conntrack.  Although that would make things a lot
 839          * simpler, we'd end up flushing all conntracks on nat rmmod.
 840          */
 841         return 0;
 842 }
 843
 844 /* No one using conntrack by the time this called. */
 845 static void nf_nat_cleanup_conntrack(struct nf_conn *ct)
 846 {
 847         if (ct->status & IPS_SRC_NAT_DONE)
 848                 __nf_nat_cleanup_conntrack(ct);
 849 }
 850
 851 static struct nf_ct_ext_type nat_extend __read_mostly = {
 852         .len            = sizeof(struct nf_conn_nat),
 853         .align          = __alignof__(struct nf_conn_nat),
 854         .destroy        = nf_nat_cleanup_conntrack,
 855         .id             = NF_CT_EXT_NAT,
 856 };
 857
 858 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 859
 860 #include <linux/netfilter/nfnetlink.h>
 861 #include <linux/netfilter/nfnetlink_conntrack.h>
 862
 863 static const struct nla_policy protonat_nla_policy[CTA_PROTONAT_MAX+1] = {
 864         [CTA_PROTONAT_PORT_MIN] = { .type = NLA_U16 },
 865         [CTA_PROTONAT_PORT_MAX] = { .type = NLA_U16 },
 866 };
 867
 868 static int nf_nat_l4proto_nlattr_to_range(struct nlattr *tb[],
 869                                           struct nf_nat_range2 *range)
 870 {
 871         if (tb[CTA_PROTONAT_PORT_MIN]) {
 872                 range->min_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MIN]);
 873                 range->max_proto.all = range->min_proto.all;
 874                 range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
 875         }
 876         if (tb[CTA_PROTONAT_PORT_MAX]) {
 877                 range->max_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MAX]);
 878                 range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
 879         }
 880         return 0;
 881 }
 882
 883 static int nfnetlink_parse_nat_proto(struct nlattr *attr,
 884                                      const struct nf_conn *ct,
 885                                      struct nf_nat_range2 *range)
 886 {
 887         struct nlattr *tb[CTA_PROTONAT_MAX+1];
 888         int err;
 889
 890         err = nla_parse_nested_deprecated(tb, CTA_PROTONAT_MAX, attr,
 891                                           protonat_nla_policy, NULL);
 892         if (err < 0)
 893                 return err;
 894
 895         return nf_nat_l4proto_nlattr_to_range(tb, range);
 896 }
 897
 898 static const struct nla_policy nat_nla_policy[CTA_NAT_MAX+1] = {
 899         [CTA_NAT_V4_MINIP]      = { .type = NLA_U32 },
 900         [CTA_NAT_V4_MAXIP]      = { .type = NLA_U32 },
 901         [CTA_NAT_V6_MINIP]      = { .len = sizeof(struct in6_addr) },
 902         [CTA_NAT_V6_MAXIP]      = { .len = sizeof(struct in6_addr) },
 903         [CTA_NAT_PROTO]         = { .type = NLA_NESTED },
 904 };
 905
 906 static int nf_nat_ipv4_nlattr_to_range(struct nlattr *tb[],
 907                                        struct nf_nat_range2 *range)
 908 {
 909         if (tb[CTA_NAT_V4_MINIP]) {
 910                 range->min_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MINIP]);
 911                 range->flags |= NF_NAT_RANGE_MAP_IPS;
 912         }
 913
 914         if (tb[CTA_NAT_V4_MAXIP])
 915                 range->max_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MAXIP]);
 916         else
 917                 range->max_addr.ip = range->min_addr.ip;
 918
 919         return 0;
 920 }
 921
 922 static int nf_nat_ipv6_nlattr_to_range(struct nlattr *tb[],
 923                                        struct nf_nat_range2 *range)
 924 {
 925         if (tb[CTA_NAT_V6_MINIP]) {
 926                 nla_memcpy(&range->min_addr.ip6, tb[CTA_NAT_V6_MINIP],
 927                            sizeof(struct in6_addr));
 928                 range->flags |= NF_NAT_RANGE_MAP_IPS;
 929         }
 930
 931         if (tb[CTA_NAT_V6_MAXIP])
 932                 nla_memcpy(&range->max_addr.ip6, tb[CTA_NAT_V6_MAXIP],
 933                            sizeof(struct in6_addr));
 934         else
 935                 range->max_addr = range->min_addr;
 936
 937         return 0;
 938 }
 939
 940 static int
 941 nfnetlink_parse_nat(const struct nlattr *nat,
 942                     const struct nf_conn *ct, struct nf_nat_range2 *range)
 943 {
 944         struct nlattr *tb[CTA_NAT_MAX+1];
 945         int err;
 946
 947         memset(range, 0, sizeof(*range));
 948
 949         err = nla_parse_nested_deprecated(tb, CTA_NAT_MAX, nat,
 950                                           nat_nla_policy, NULL);
 951         if (err < 0)
 952                 return err;
 953
 954         switch (nf_ct_l3num(ct)) {
 955         case NFPROTO_IPV4:
 956                 err = nf_nat_ipv4_nlattr_to_range(tb, range);
 957                 break;
 958         case NFPROTO_IPV6:
 959                 err = nf_nat_ipv6_nlattr_to_range(tb, range);
 960                 break;
 961         default:
 962                 err = -EPROTONOSUPPORT;
 963                 break;
 964         }
 965
 966         if (err)
 967                 return err;
 968
 969         if (!tb[CTA_NAT_PROTO])
 970                 return 0;
 971
 972         return nfnetlink_parse_nat_proto(tb[CTA_NAT_PROTO], ct, range);
 973 }
 974
 975 /* This function is called under rcu_read_lock() */
 976 static int
 977 nfnetlink_parse_nat_setup(struct nf_conn *ct,
 978                           enum nf_nat_manip_type manip,
 979                           const struct nlattr *attr)
 980 {
 981         struct nf_nat_range2 range;
 982         int err;
 983
 984         /* Should not happen, restricted to creating new conntracks
 985          * via ctnetlink.
 986          */
 987         if (WARN_ON_ONCE(nf_nat_initialized(ct, manip)))
 988                 return -EEXIST;
 989
 990         /* No NAT information has been passed, allocate the null-binding */
 991         if (attr == NULL)
 992                 return __nf_nat_alloc_null_binding(ct, manip) == NF_DROP ? -ENOMEM : 0;
 993
 994         err = nfnetlink_parse_nat(attr, ct, &range);
 995         if (err < 0)
 996                 return err;
 997
 998         return nf_nat_setup_info(ct, &range, manip) == NF_DROP ? -ENOMEM : 0;
 999 }
1000 #else
1001 static int
1002 nfnetlink_parse_nat_setup(struct nf_conn *ct,
1003                           enum nf_nat_manip_type manip,
1004                           const struct nlattr *attr)
1005 {
1006         return -EOPNOTSUPP;
1007 }
1008 #endif
1009
1010 static struct nf_ct_helper_expectfn follow_master_nat = {
1011         .name           = "nat-follow-master",
1012         .expectfn       = nf_nat_follow_master,
1013 };
1014
1015 int nf_nat_register_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
1016                        const struct nf_hook_ops *orig_nat_ops, unsigned int ops_count)
1017 {
1018         struct nat_net *nat_net = net_generic(net, nat_net_id);
1019         struct nf_nat_hooks_net *nat_proto_net;
1020         struct nf_nat_lookup_hook_priv *priv;
1021         unsigned int hooknum = ops->hooknum;
1022         struct nf_hook_ops *nat_ops;
1023         int i, ret;
1024
1025         if (WARN_ON_ONCE(pf >= ARRAY_SIZE(nat_net->nat_proto_net)))
1026                 return -EINVAL;
1027
1028         nat_proto_net = &nat_net->nat_proto_net[pf];
1029
1030         for (i = 0; i < ops_count; i++) {
1031                 if (orig_nat_ops[i].hooknum == hooknum) {
1032                         hooknum = i;
1033                         break;
1034                 }
1035         }
1036
1037         if (WARN_ON_ONCE(i == ops_count))
1038                 return -EINVAL;
1039
1040         mutex_lock(&nf_nat_proto_mutex);
1041         if (!nat_proto_net->nat_hook_ops) {
1042                 WARN_ON(nat_proto_net->users != 0);
1043
1044                 nat_ops = kmemdup(orig_nat_ops, sizeof(*orig_nat_ops) * ops_count, GFP_KERNEL);
1045                 if (!nat_ops) {
1046                         mutex_unlock(&nf_nat_proto_mutex);
1047                         return -ENOMEM;
1048                 }
1049
1050                 for (i = 0; i < ops_count; i++) {
1051                         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
1052                         if (priv) {
1053                                 nat_ops[i].priv = priv;
1054                                 continue;
1055                         }
1056                         mutex_unlock(&nf_nat_proto_mutex);
1057                         while (i)
1058                                 kfree(nat_ops[--i].priv);
1059                         kfree(nat_ops);
1060                         return -ENOMEM;
1061                 }
1062
1063                 ret = nf_register_net_hooks(net, nat_ops, ops_count);
1064                 if (ret < 0) {
1065                         mutex_unlock(&nf_nat_proto_mutex);
1066                         for (i = 0; i < ops_count; i++)
1067                                 kfree(nat_ops[i].priv);
1068                         kfree(nat_ops);
1069                         return ret;
1070                 }
1071
1072                 nat_proto_net->nat_hook_ops = nat_ops;
1073         }
1074
1075         nat_ops = nat_proto_net->nat_hook_ops;
1076         priv = nat_ops[hooknum].priv;
1077         if (WARN_ON_ONCE(!priv)) {
1078                 mutex_unlock(&nf_nat_proto_mutex);
1079                 return -EOPNOTSUPP;
1080         }
1081
1082         ret = nf_hook_entries_insert_raw(&priv->entries, ops);
1083         if (ret == 0)
1084                 nat_proto_net->users++;
1085
1086         mutex_unlock(&nf_nat_proto_mutex);
1087         return ret;
1088 }
1089
1090 void nf_nat_unregister_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
1091                           unsigned int ops_count)
1092 {
1093         struct nat_net *nat_net = net_generic(net, nat_net_id);
1094         struct nf_nat_hooks_net *nat_proto_net;
1095         struct nf_nat_lookup_hook_priv *priv;
1096         struct nf_hook_ops *nat_ops;
1097         int hooknum = ops->hooknum;
1098         int i;
1099
1100         if (pf >= ARRAY_SIZE(nat_net->nat_proto_net))
1101                 return;
1102
1103         nat_proto_net = &nat_net->nat_proto_net[pf];
1104
1105         mutex_lock(&nf_nat_proto_mutex);
1106         if (WARN_ON(nat_proto_net->users == 0))
1107                 goto unlock;
1108
1109         nat_proto_net->users--;
1110
1111         nat_ops = nat_proto_net->nat_hook_ops;
1112         for (i = 0; i < ops_count; i++) {
1113                 if (nat_ops[i].hooknum == hooknum) {
1114                         hooknum = i;
1115                         break;
1116                 }
1117         }
1118         if (WARN_ON_ONCE(i == ops_count))
1119                 goto unlock;
1120         priv = nat_ops[hooknum].priv;
1121         nf_hook_entries_delete_raw(&priv->entries, ops);
1122
1123         if (nat_proto_net->users == 0) {
1124                 nf_unregister_net_hooks(net, nat_ops, ops_count);
1125
1126                 for (i = 0; i < ops_count; i++) {
1127                         priv = nat_ops[i].priv;
1128                         kfree_rcu(priv, rcu_head);
1129                 }
1130
1131                 nat_proto_net->nat_hook_ops = NULL;
1132                 kfree(nat_ops);
1133         }
1134 unlock:
1135         mutex_unlock(&nf_nat_proto_mutex);
1136 }
1137
1138 static struct pernet_operations nat_net_ops = {
1139         .id = &nat_net_id,
1140         .size = sizeof(struct nat_net),
1141 };
1142
1143 static struct nf_nat_hook nat_hook = {
1144         .parse_nat_setup        = nfnetlink_parse_nat_setup,
1145 #ifdef CONFIG_XFRM
1146         .decode_session         = __nf_nat_decode_session,
1147 #endif
1148         .manip_pkt              = nf_nat_manip_pkt,
1149 };
1150
1151 static int __init nf_nat_init(void)
1152 {
1153         int ret, i;
1154
1155         /* Leave them the same for the moment. */
1156         nf_nat_htable_size = nf_conntrack_htable_size;
1157         if (nf_nat_htable_size < CONNTRACK_LOCKS)
1158                 nf_nat_htable_size = CONNTRACK_LOCKS;
1159
1160         nf_nat_bysource = nf_ct_alloc_hashtable(&nf_nat_htable_size, 0);
1161         if (!nf_nat_bysource)
1162                 return -ENOMEM;
1163
1164         ret = nf_ct_extend_register(&nat_extend);
1165         if (ret < 0) {
1166                 kvfree(nf_nat_bysource);
1167                 pr_err("Unable to register extension\n");
1168                 return ret;
1169         }
1170
1171         for (i = 0; i < CONNTRACK_LOCKS; i++)
1172                 spin_lock_init(&nf_nat_locks[i]);
1173
1174         ret = register_pernet_subsys(&nat_net_ops);
1175         if (ret < 0) {
1176                 nf_ct_extend_unregister(&nat_extend);
1177                 return ret;
1178         }
1179
1180         nf_ct_helper_expectfn_register(&follow_master_nat);
1181
1182         WARN_ON(nf_nat_hook != NULL);
1183         RCU_INIT_POINTER(nf_nat_hook, &nat_hook);
1184
1185         return 0;
1186 }
1187
1188 static void __exit nf_nat_cleanup(void)
1189 {
1190         struct nf_nat_proto_clean clean = {};
1191
1192         nf_ct_iterate_destroy(nf_nat_proto_clean, &clean);
1193
1194         nf_ct_extend_unregister(&nat_extend);
1195         nf_ct_helper_expectfn_unregister(&follow_master_nat);
1196         RCU_INIT_POINTER(nf_nat_hook, NULL);
1197
1198         synchronize_net();
1199         kvfree(nf_nat_bysource);
1200         unregister_pernet_subsys(&nat_net_ops);
1201 }
1202
1203 MODULE_LICENSE("GPL");
1204
1205 module_init(nf_nat_init);
1206 module_exit(nf_nat_cleanup);