net/ipv4/netfilter/nf_nat_core.c

   1 /* NAT for netfilter; shared with compatibility layer. */
   2
   3 /* (C) 1999-2001 Paul `Rusty' Russell
   4  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
   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 #include <linux/module.h>
  12 #include <linux/types.h>
  13 #include <linux/timer.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/gfp.h>
  16 #include <net/checksum.h>
  17 #include <net/icmp.h>
  18 #include <net/ip.h>
  19 #include <net/tcp.h>  /* For tcp_prot in getorigdst */
  20 #include <linux/icmp.h>
  21 #include <linux/udp.h>
  22 #include <linux/jhash.h>
  23
  24 #include <linux/netfilter_ipv4.h>
  25 #include <net/netfilter/nf_conntrack.h>
  26 #include <net/netfilter/nf_conntrack_core.h>
  27 #include <net/netfilter/nf_nat.h>
  28 #include <net/netfilter/nf_nat_protocol.h>
  29 #include <net/netfilter/nf_nat_core.h>
  30 #include <net/netfilter/nf_nat_helper.h>
  31 #include <net/netfilter/nf_conntrack_helper.h>
  32 #include <net/netfilter/nf_conntrack_l3proto.h>
  33 #include <net/netfilter/nf_conntrack_l4proto.h>
  34 #include <net/netfilter/nf_conntrack_zones.h>
  35
  36 static DEFINE_SPINLOCK(nf_nat_lock);
  37
  38 static struct nf_conntrack_l3proto *l3proto __read_mostly;
  39
  40 #define MAX_IP_NAT_PROTO 256
  41 static const struct nf_nat_protocol *nf_nat_protos[MAX_IP_NAT_PROTO]
  42                                                 __read_mostly;
  43
  44 static inline const struct nf_nat_protocol *
  45 __nf_nat_proto_find(u_int8_t protonum)
  46 {
  47         return rcu_dereference(nf_nat_protos[protonum]);
  48 }
  49
  50 const struct nf_nat_protocol *
  51 nf_nat_proto_find_get(u_int8_t protonum)
  52 {
  53         const struct nf_nat_protocol *p;
  54
  55         rcu_read_lock();
  56         p = __nf_nat_proto_find(protonum);
  57         if (!try_module_get(p->me))
  58                 p = &nf_nat_unknown_protocol;
  59         rcu_read_unlock();
  60
  61         return p;
  62 }
  63 EXPORT_SYMBOL_GPL(nf_nat_proto_find_get);
  64
  65 void
  66 nf_nat_proto_put(const struct nf_nat_protocol *p)
  67 {
  68         module_put(p->me);
  69 }
  70 EXPORT_SYMBOL_GPL(nf_nat_proto_put);
  71
  72 /* We keep an extra hash for each conntrack, for fast searching. */
  73 static inline unsigned int
  74 hash_by_src(const struct net *net, u16 zone,
  75             const struct nf_conntrack_tuple *tuple)
  76 {
  77         unsigned int hash;
  78
  79         /* Original src, to ensure we map it consistently if poss. */
  80         hash = jhash_3words((__force u32)tuple->src.u3.ip,
  81                             (__force u32)tuple->src.u.all ^ zone,
  82                             tuple->dst.protonum, 0);
  83         return ((u64)hash * net->ipv4.nat_htable_size) >> 32;
  84 }
  85
  86 /* Is this tuple already taken? (not by us) */
  87 int
  88 nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple,
  89                   const struct nf_conn *ignored_conntrack)
  90 {
  91         /* Conntrack tracking doesn't keep track of outgoing tuples; only
  92            incoming ones.  NAT means they don't have a fixed mapping,
  93            so we invert the tuple and look for the incoming reply.
  94
  95            We could keep a separate hash if this proves too slow. */
  96         struct nf_conntrack_tuple reply;
  97
  98         nf_ct_invert_tuplepr(&reply, tuple);
  99         return nf_conntrack_tuple_taken(&reply, ignored_conntrack);
 100 }
 101 EXPORT_SYMBOL(nf_nat_used_tuple);
 102
 103 /* If we source map this tuple so reply looks like reply_tuple, will
 104  * that meet the constraints of range. */
 105 static int
 106 in_range(const struct nf_conntrack_tuple *tuple,
 107          const struct nf_nat_range *range)
 108 {
 109         const struct nf_nat_protocol *proto;
 110         int ret = 0;
 111
 112         /* If we are supposed to map IPs, then we must be in the
 113            range specified, otherwise let this drag us onto a new src IP. */
 114         if (range->flags & IP_NAT_RANGE_MAP_IPS) {
 115                 if (ntohl(tuple->src.u3.ip) < ntohl(range->min_ip) ||
 116                     ntohl(tuple->src.u3.ip) > ntohl(range->max_ip))
 117                         return 0;
 118         }
 119
 120         rcu_read_lock();
 121         proto = __nf_nat_proto_find(tuple->dst.protonum);
 122         if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED) ||
 123             proto->in_range(tuple, IP_NAT_MANIP_SRC,
 124                             &range->min, &range->max))
 125                 ret = 1;
 126         rcu_read_unlock();
 127
 128         return ret;
 129 }
 130
 131 static inline int
 132 same_src(const struct nf_conn *ct,
 133          const struct nf_conntrack_tuple *tuple)
 134 {
 135         const struct nf_conntrack_tuple *t;
 136
 137         t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
 138         return (t->dst.protonum == tuple->dst.protonum &&
 139                 t->src.u3.ip == tuple->src.u3.ip &&
 140                 t->src.u.all == tuple->src.u.all);
 141 }
 142
 143 /* Only called for SRC manip */
 144 static int
 145 find_appropriate_src(struct net *net, u16 zone,
 146                      const struct nf_conntrack_tuple *tuple,
 147                      struct nf_conntrack_tuple *result,
 148                      const struct nf_nat_range *range)
 149 {
 150         unsigned int h = hash_by_src(net, zone, tuple);
 151         const struct nf_conn_nat *nat;
 152         const struct nf_conn *ct;
 153         const struct hlist_node *n;
 154
 155         rcu_read_lock();
 156         hlist_for_each_entry_rcu(nat, n, &net->ipv4.nat_bysource[h], bysource) {
 157                 ct = nat->ct;
 158                 if (same_src(ct, tuple) && nf_ct_zone(ct) == zone) {
 159                         /* Copy source part from reply tuple. */
 160                         nf_ct_invert_tuplepr(result,
 161                                        &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
 162                         result->dst = tuple->dst;
 163
 164                         if (in_range(result, range)) {
 165                                 rcu_read_unlock();
 166                                 return 1;
 167                         }
 168                 }
 169         }
 170         rcu_read_unlock();
 171         return 0;
 172 }
 173
 174 /* For [FUTURE] fragmentation handling, we want the least-used
 175    src-ip/dst-ip/proto triple.  Fairness doesn't come into it.  Thus
 176    if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports
 177    1-65535, we don't do pro-rata allocation based on ports; we choose
 178    the ip with the lowest src-ip/dst-ip/proto usage.
 179 */
 180 static void
 181 find_best_ips_proto(u16 zone, struct nf_conntrack_tuple *tuple,
 182                     const struct nf_nat_range *range,
 183                     const struct nf_conn *ct,
 184                     enum nf_nat_manip_type maniptype)
 185 {
 186         __be32 *var_ipp;
 187         /* Host order */
 188         u_int32_t minip, maxip, j;
 189
 190         /* No IP mapping?  Do nothing. */
 191         if (!(range->flags & IP_NAT_RANGE_MAP_IPS))
 192                 return;
 193
 194         if (maniptype == IP_NAT_MANIP_SRC)
 195                 var_ipp = &tuple->src.u3.ip;
 196         else
 197                 var_ipp = &tuple->dst.u3.ip;
 198
 199         /* Fast path: only one choice. */
 200         if (range->min_ip == range->max_ip) {
 201                 *var_ipp = range->min_ip;
 202                 return;
 203         }
 204
 205         /* Hashing source and destination IPs gives a fairly even
 206          * spread in practice (if there are a small number of IPs
 207          * involved, there usually aren't that many connections
 208          * anyway).  The consistency means that servers see the same
 209          * client coming from the same IP (some Internet Banking sites
 210          * like this), even across reboots. */
 211         minip = ntohl(range->min_ip);
 212         maxip = ntohl(range->max_ip);
 213         j = jhash_2words((__force u32)tuple->src.u3.ip,
 214                          range->flags & IP_NAT_RANGE_PERSISTENT ?
 215                                 0 : (__force u32)tuple->dst.u3.ip ^ zone, 0);
 216         j = ((u64)j * (maxip - minip + 1)) >> 32;
 217         *var_ipp = htonl(minip + j);
 218 }
 219
 220 /* Manipulate the tuple into the range given.  For NF_INET_POST_ROUTING,
 221  * we change the source to map into the range.  For NF_INET_PRE_ROUTING
 222  * and NF_INET_LOCAL_OUT, we change the destination to map into the
 223  * range.  It might not be possible to get a unique tuple, but we try.
 224  * At worst (or if we race), we will end up with a final duplicate in
 225  * __ip_conntrack_confirm and drop the packet. */
 226 static void
 227 get_unique_tuple(struct nf_conntrack_tuple *tuple,
 228                  const struct nf_conntrack_tuple *orig_tuple,
 229                  const struct nf_nat_range *range,
 230                  struct nf_conn *ct,
 231                  enum nf_nat_manip_type maniptype)
 232 {
 233         struct net *net = nf_ct_net(ct);
 234         const struct nf_nat_protocol *proto;
 235         u16 zone = nf_ct_zone(ct);
 236
 237         /* 1) If this srcip/proto/src-proto-part is currently mapped,
 238            and that same mapping gives a unique tuple within the given
 239            range, use that.
 240
 241            This is only required for source (ie. NAT/masq) mappings.
 242            So far, we don't do local source mappings, so multiple
 243            manips not an issue.  */
 244         if (maniptype == IP_NAT_MANIP_SRC &&
 245             !(range->flags & IP_NAT_RANGE_PROTO_RANDOM)) {
 246                 if (find_appropriate_src(net, zone, orig_tuple, tuple, range)) {
 247                         pr_debug("get_unique_tuple: Found current src map\n");
 248                         if (!nf_nat_used_tuple(tuple, ct))
 249                                 return;
 250                 }
 251         }
 252
 253         /* 2) Select the least-used IP/proto combination in the given
 254            range. */
 255         *tuple = *orig_tuple;
 256         find_best_ips_proto(zone, tuple, range, ct, maniptype);
 257
 258         /* 3) The per-protocol part of the manip is made to map into
 259            the range to make a unique tuple. */
 260
 261         rcu_read_lock();
 262         proto = __nf_nat_proto_find(orig_tuple->dst.protonum);
 263
 264         /* Change protocol info to have some randomization */
 265         if (range->flags & IP_NAT_RANGE_PROTO_RANDOM) {
 266                 proto->unique_tuple(tuple, range, maniptype, ct);
 267                 goto out;
 268         }
 269
 270         /* Only bother mapping if it's not already in range and unique */
 271         if ((!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED) ||
 272              proto->in_range(tuple, maniptype, &range->min, &range->max)) &&
 273             !nf_nat_used_tuple(tuple, ct))
 274                 goto out;
 275
 276         /* Last change: get protocol to try to obtain unique tuple. */
 277         proto->unique_tuple(tuple, range, maniptype, ct);
 278 out:
 279         rcu_read_unlock();
 280 }
 281
 282 unsigned int
 283 nf_nat_setup_info(struct nf_conn *ct,
 284                   const struct nf_nat_range *range,
 285                   enum nf_nat_manip_type maniptype)
 286 {
 287         struct net *net = nf_ct_net(ct);
 288         struct nf_conntrack_tuple curr_tuple, new_tuple;
 289         struct nf_conn_nat *nat;
 290         int have_to_hash = !(ct->status & IPS_NAT_DONE_MASK);
 291
 292         /* nat helper or nfctnetlink also setup binding */
 293         nat = nfct_nat(ct);
 294         if (!nat) {
 295                 nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
 296                 if (nat == NULL) {
 297                         pr_debug("failed to add NAT extension\n");
 298                         return NF_ACCEPT;
 299                 }
 300         }
 301
 302         NF_CT_ASSERT(maniptype == IP_NAT_MANIP_SRC ||
 303                      maniptype == IP_NAT_MANIP_DST);
 304         BUG_ON(nf_nat_initialized(ct, maniptype));
 305
 306         /* What we've got will look like inverse of reply. Normally
 307            this is what is in the conntrack, except for prior
 308            manipulations (future optimization: if num_manips == 0,
 309            orig_tp =
 310            conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple) */
 311         nf_ct_invert_tuplepr(&curr_tuple,
 312                              &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
 313
 314         get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype);
 315
 316         if (!nf_ct_tuple_equal(&new_tuple, &curr_tuple)) {
 317                 struct nf_conntrack_tuple reply;
 318
 319                 /* Alter conntrack table so will recognize replies. */
 320                 nf_ct_invert_tuplepr(&reply, &new_tuple);
 321                 nf_conntrack_alter_reply(ct, &reply);
 322
 323                 /* Non-atomic: we own this at the moment. */
 324                 if (maniptype == IP_NAT_MANIP_SRC)
 325                         ct->status |= IPS_SRC_NAT;
 326                 else
 327                         ct->status |= IPS_DST_NAT;
 328         }
 329
 330         /* Place in source hash if this is the first time. */
 331         if (have_to_hash) {
 332                 unsigned int srchash;
 333
 334                 srchash = hash_by_src(net, nf_ct_zone(ct),
 335                                       &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
 336                 spin_lock_bh(&nf_nat_lock);
 337                 /* nf_conntrack_alter_reply might re-allocate exntension aera */
 338                 nat = nfct_nat(ct);
 339                 nat->ct = ct;
 340                 hlist_add_head_rcu(&nat->bysource,
 341                                    &net->ipv4.nat_bysource[srchash]);
 342                 spin_unlock_bh(&nf_nat_lock);
 343         }
 344
 345         /* It's done. */
 346         if (maniptype == IP_NAT_MANIP_DST)
 347                 set_bit(IPS_DST_NAT_DONE_BIT, &ct->status);
 348         else
 349                 set_bit(IPS_SRC_NAT_DONE_BIT, &ct->status);
 350
 351         return NF_ACCEPT;
 352 }
 353 EXPORT_SYMBOL(nf_nat_setup_info);
 354
 355 /* Returns true if succeeded. */
 356 static bool
 357 manip_pkt(u_int16_t proto,
 358           struct sk_buff *skb,
 359           unsigned int iphdroff,
 360           const struct nf_conntrack_tuple *target,
 361           enum nf_nat_manip_type maniptype)
 362 {
 363         struct iphdr *iph;
 364         const struct nf_nat_protocol *p;
 365
 366         if (!skb_make_writable(skb, iphdroff + sizeof(*iph)))
 367                 return false;
 368
 369         iph = (void *)skb->data + iphdroff;
 370
 371         /* Manipulate protcol part. */
 372
 373         /* rcu_read_lock()ed by nf_hook_slow */
 374         p = __nf_nat_proto_find(proto);
 375         if (!p->manip_pkt(skb, iphdroff, target, maniptype))
 376                 return false;
 377
 378         iph = (void *)skb->data + iphdroff;
 379
 380         if (maniptype == IP_NAT_MANIP_SRC) {
 381                 csum_replace4(&iph->check, iph->saddr, target->src.u3.ip);
 382                 iph->saddr = target->src.u3.ip;
 383         } else {
 384                 csum_replace4(&iph->check, iph->daddr, target->dst.u3.ip);
 385                 iph->daddr = target->dst.u3.ip;
 386         }
 387         return true;
 388 }
 389
 390 /* Do packet manipulations according to nf_nat_setup_info. */
 391 unsigned int nf_nat_packet(struct nf_conn *ct,
 392                            enum ip_conntrack_info ctinfo,
 393                            unsigned int hooknum,
 394                            struct sk_buff *skb)
 395 {
 396         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 397         unsigned long statusbit;
 398         enum nf_nat_manip_type mtype = HOOK2MANIP(hooknum);
 399
 400         if (mtype == IP_NAT_MANIP_SRC)
 401                 statusbit = IPS_SRC_NAT;
 402         else
 403                 statusbit = IPS_DST_NAT;
 404
 405         /* Invert if this is reply dir. */
 406         if (dir == IP_CT_DIR_REPLY)
 407                 statusbit ^= IPS_NAT_MASK;
 408
 409         /* Non-atomic: these bits don't change. */
 410         if (ct->status & statusbit) {
 411                 struct nf_conntrack_tuple target;
 412
 413                 /* We are aiming to look like inverse of other direction. */
 414                 nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
 415
 416                 if (!manip_pkt(target.dst.protonum, skb, 0, &target, mtype))
 417                         return NF_DROP;
 418         }
 419         return NF_ACCEPT;
 420 }
 421 EXPORT_SYMBOL_GPL(nf_nat_packet);
 422
 423 /* Dir is direction ICMP is coming from (opposite to packet it contains) */
 424 int nf_nat_icmp_reply_translation(struct nf_conn *ct,
 425                                   enum ip_conntrack_info ctinfo,
 426                                   unsigned int hooknum,
 427                                   struct sk_buff *skb)
 428 {
 429         struct {
 430                 struct icmphdr icmp;
 431                 struct iphdr ip;
 432         } *inside;
 433         const struct nf_conntrack_l4proto *l4proto;
 434         struct nf_conntrack_tuple inner, target;
 435         int hdrlen = ip_hdrlen(skb);
 436         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 437         unsigned long statusbit;
 438         enum nf_nat_manip_type manip = HOOK2MANIP(hooknum);
 439
 440         if (!skb_make_writable(skb, hdrlen + sizeof(*inside)))
 441                 return 0;
 442
 443         inside = (void *)skb->data + ip_hdrlen(skb);
 444
 445         /* We're actually going to mangle it beyond trivial checksum
 446            adjustment, so make sure the current checksum is correct. */
 447         if (nf_ip_checksum(skb, hooknum, hdrlen, 0))
 448                 return 0;
 449
 450         /* Must be RELATED */
 451         NF_CT_ASSERT(skb->nfctinfo == IP_CT_RELATED ||
 452                      skb->nfctinfo == IP_CT_RELATED+IP_CT_IS_REPLY);
 453
 454         /* Redirects on non-null nats must be dropped, else they'll
 455            start talking to each other without our translation, and be
 456            confused... --RR */
 457         if (inside->icmp.type == ICMP_REDIRECT) {
 458                 /* If NAT isn't finished, assume it and drop. */
 459                 if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
 460                         return 0;
 461
 462                 if (ct->status & IPS_NAT_MASK)
 463                         return 0;
 464         }
 465
 466         pr_debug("icmp_reply_translation: translating error %p manip %u "
 467                  "dir %s\n", skb, manip,
 468                  dir == IP_CT_DIR_ORIGINAL ? "ORIG" : "REPLY");
 469
 470         /* rcu_read_lock()ed by nf_hook_slow */
 471         l4proto = __nf_ct_l4proto_find(PF_INET, inside->ip.protocol);
 472
 473         if (!nf_ct_get_tuple(skb,
 474                              ip_hdrlen(skb) + sizeof(struct icmphdr),
 475                              (ip_hdrlen(skb) +
 476                               sizeof(struct icmphdr) + inside->ip.ihl * 4),
 477                              (u_int16_t)AF_INET,
 478                              inside->ip.protocol,
 479                              &inner, l3proto, l4proto))
 480                 return 0;
 481
 482         /* Change inner back to look like incoming packet.  We do the
 483            opposite manip on this hook to normal, because it might not
 484            pass all hooks (locally-generated ICMP).  Consider incoming
 485            packet: PREROUTING (DST manip), routing produces ICMP, goes
 486            through POSTROUTING (which must correct the DST manip). */
 487         if (!manip_pkt(inside->ip.protocol, skb,
 488                        ip_hdrlen(skb) + sizeof(inside->icmp),
 489                        &ct->tuplehash[!dir].tuple,
 490                        !manip))
 491                 return 0;
 492
 493         if (skb->ip_summed != CHECKSUM_PARTIAL) {
 494                 /* Reloading "inside" here since manip_pkt inner. */
 495                 inside = (void *)skb->data + ip_hdrlen(skb);
 496                 inside->icmp.checksum = 0;
 497                 inside->icmp.checksum =
 498                         csum_fold(skb_checksum(skb, hdrlen,
 499                                                skb->len - hdrlen, 0));
 500         }
 501
 502         /* Change outer to look the reply to an incoming packet
 503          * (proto 0 means don't invert per-proto part). */
 504         if (manip == IP_NAT_MANIP_SRC)
 505                 statusbit = IPS_SRC_NAT;
 506         else
 507                 statusbit = IPS_DST_NAT;
 508
 509         /* Invert if this is reply dir. */
 510         if (dir == IP_CT_DIR_REPLY)
 511                 statusbit ^= IPS_NAT_MASK;
 512
 513         if (ct->status & statusbit) {
 514                 nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
 515                 if (!manip_pkt(0, skb, 0, &target, manip))
 516                         return 0;
 517         }
 518
 519         return 1;
 520 }
 521 EXPORT_SYMBOL_GPL(nf_nat_icmp_reply_translation);
 522
 523 /* Protocol registration. */
 524 int nf_nat_protocol_register(const struct nf_nat_protocol *proto)
 525 {
 526         int ret = 0;
 527
 528         spin_lock_bh(&nf_nat_lock);
 529         if (nf_nat_protos[proto->protonum] != &nf_nat_unknown_protocol) {
 530                 ret = -EBUSY;
 531                 goto out;
 532         }
 533         rcu_assign_pointer(nf_nat_protos[proto->protonum], proto);
 534  out:
 535         spin_unlock_bh(&nf_nat_lock);
 536         return ret;
 537 }
 538 EXPORT_SYMBOL(nf_nat_protocol_register);
 539
 540 /* Noone stores the protocol anywhere; simply delete it. */
 541 void nf_nat_protocol_unregister(const struct nf_nat_protocol *proto)
 542 {
 543         spin_lock_bh(&nf_nat_lock);
 544         rcu_assign_pointer(nf_nat_protos[proto->protonum],
 545                            &nf_nat_unknown_protocol);
 546         spin_unlock_bh(&nf_nat_lock);
 547         synchronize_rcu();
 548 }
 549 EXPORT_SYMBOL(nf_nat_protocol_unregister);
 550
 551 /* Noone using conntrack by the time this called. */
 552 static void nf_nat_cleanup_conntrack(struct nf_conn *ct)
 553 {
 554         struct nf_conn_nat *nat = nf_ct_ext_find(ct, NF_CT_EXT_NAT);
 555
 556         if (nat == NULL || nat->ct == NULL)
 557                 return;
 558
 559         NF_CT_ASSERT(nat->ct->status & IPS_NAT_DONE_MASK);
 560
 561         spin_lock_bh(&nf_nat_lock);
 562         hlist_del_rcu(&nat->bysource);
 563         spin_unlock_bh(&nf_nat_lock);
 564 }
 565
 566 static void nf_nat_move_storage(void *new, void *old)
 567 {
 568         struct nf_conn_nat *new_nat = new;
 569         struct nf_conn_nat *old_nat = old;
 570         struct nf_conn *ct = old_nat->ct;
 571
 572         if (!ct || !(ct->status & IPS_NAT_DONE_MASK))
 573                 return;
 574
 575         spin_lock_bh(&nf_nat_lock);
 576         new_nat->ct = ct;
 577         hlist_replace_rcu(&old_nat->bysource, &new_nat->bysource);
 578         spin_unlock_bh(&nf_nat_lock);
 579 }
 580
 581 static struct nf_ct_ext_type nat_extend __read_mostly = {
 582         .len            = sizeof(struct nf_conn_nat),
 583         .align          = __alignof__(struct nf_conn_nat),
 584         .destroy        = nf_nat_cleanup_conntrack,
 585         .move           = nf_nat_move_storage,
 586         .id             = NF_CT_EXT_NAT,
 587         .flags          = NF_CT_EXT_F_PREALLOC,
 588 };
 589
 590 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 591
 592 #include <linux/netfilter/nfnetlink.h>
 593 #include <linux/netfilter/nfnetlink_conntrack.h>
 594
 595 static const struct nla_policy protonat_nla_policy[CTA_PROTONAT_MAX+1] = {
 596         [CTA_PROTONAT_PORT_MIN] = { .type = NLA_U16 },
 597         [CTA_PROTONAT_PORT_MAX] = { .type = NLA_U16 },
 598 };
 599
 600 static int nfnetlink_parse_nat_proto(struct nlattr *attr,
 601                                      const struct nf_conn *ct,
 602                                      struct nf_nat_range *range)
 603 {
 604         struct nlattr *tb[CTA_PROTONAT_MAX+1];
 605         const struct nf_nat_protocol *npt;
 606         int err;
 607
 608         err = nla_parse_nested(tb, CTA_PROTONAT_MAX, attr, protonat_nla_policy);
 609         if (err < 0)
 610                 return err;
 611
 612         npt = nf_nat_proto_find_get(nf_ct_protonum(ct));
 613         if (npt->nlattr_to_range)
 614                 err = npt->nlattr_to_range(tb, range);
 615         nf_nat_proto_put(npt);
 616         return err;
 617 }
 618
 619 static const struct nla_policy nat_nla_policy[CTA_NAT_MAX+1] = {
 620         [CTA_NAT_MINIP]         = { .type = NLA_U32 },
 621         [CTA_NAT_MAXIP]         = { .type = NLA_U32 },
 622 };
 623
 624 static int
 625 nfnetlink_parse_nat(const struct nlattr *nat,
 626                     const struct nf_conn *ct, struct nf_nat_range *range)
 627 {
 628         struct nlattr *tb[CTA_NAT_MAX+1];
 629         int err;
 630
 631         memset(range, 0, sizeof(*range));
 632
 633         err = nla_parse_nested(tb, CTA_NAT_MAX, nat, nat_nla_policy);
 634         if (err < 0)
 635                 return err;
 636
 637         if (tb[CTA_NAT_MINIP])
 638                 range->min_ip = nla_get_be32(tb[CTA_NAT_MINIP]);
 639
 640         if (!tb[CTA_NAT_MAXIP])
 641                 range->max_ip = range->min_ip;
 642         else
 643                 range->max_ip = nla_get_be32(tb[CTA_NAT_MAXIP]);
 644
 645         if (range->min_ip)
 646                 range->flags |= IP_NAT_RANGE_MAP_IPS;
 647
 648         if (!tb[CTA_NAT_PROTO])
 649                 return 0;
 650
 651         err = nfnetlink_parse_nat_proto(tb[CTA_NAT_PROTO], ct, range);
 652         if (err < 0)
 653                 return err;
 654
 655         return 0;
 656 }
 657
 658 static int
 659 nfnetlink_parse_nat_setup(struct nf_conn *ct,
 660                           enum nf_nat_manip_type manip,
 661                           const struct nlattr *attr)
 662 {
 663         struct nf_nat_range range;
 664
 665         if (nfnetlink_parse_nat(attr, ct, &range) < 0)
 666                 return -EINVAL;
 667         if (nf_nat_initialized(ct, manip))
 668                 return -EEXIST;
 669
 670         return nf_nat_setup_info(ct, &range, manip);
 671 }
 672 #else
 673 static int
 674 nfnetlink_parse_nat_setup(struct nf_conn *ct,
 675                           enum nf_nat_manip_type manip,
 676                           const struct nlattr *attr)
 677 {
 678         return -EOPNOTSUPP;
 679 }
 680 #endif
 681
 682 static int __net_init nf_nat_net_init(struct net *net)
 683 {
 684         /* Leave them the same for the moment. */
 685         net->ipv4.nat_htable_size = net->ct.htable_size;
 686         net->ipv4.nat_bysource = nf_ct_alloc_hashtable(&net->ipv4.nat_htable_size,
 687                                                        &net->ipv4.nat_vmalloced, 0);
 688         if (!net->ipv4.nat_bysource)
 689                 return -ENOMEM;
 690         return 0;
 691 }
 692
 693 /* Clear NAT section of all conntracks, in case we're loaded again. */
 694 static int clean_nat(struct nf_conn *i, void *data)
 695 {
 696         struct nf_conn_nat *nat = nfct_nat(i);
 697
 698         if (!nat)
 699                 return 0;
 700         memset(nat, 0, sizeof(*nat));
 701         i->status &= ~(IPS_NAT_MASK | IPS_NAT_DONE_MASK | IPS_SEQ_ADJUST);
 702         return 0;
 703 }
 704
 705 static void __net_exit nf_nat_net_exit(struct net *net)
 706 {
 707         nf_ct_iterate_cleanup(net, &clean_nat, NULL);
 708         synchronize_rcu();
 709         nf_ct_free_hashtable(net->ipv4.nat_bysource, net->ipv4.nat_vmalloced,
 710                              net->ipv4.nat_htable_size);
 711 }
 712
 713 static struct pernet_operations nf_nat_net_ops = {
 714         .init = nf_nat_net_init,
 715         .exit = nf_nat_net_exit,
 716 };
 717
 718 static int __init nf_nat_init(void)
 719 {
 720         size_t i;
 721         int ret;
 722
 723         need_ipv4_conntrack();
 724
 725         ret = nf_ct_extend_register(&nat_extend);
 726         if (ret < 0) {
 727                 printk(KERN_ERR "nf_nat_core: Unable to register extension\n");
 728                 return ret;
 729         }
 730
 731         ret = register_pernet_subsys(&nf_nat_net_ops);
 732         if (ret < 0)
 733                 goto cleanup_extend;
 734
 735         /* Sew in builtin protocols. */
 736         spin_lock_bh(&nf_nat_lock);
 737         for (i = 0; i < MAX_IP_NAT_PROTO; i++)
 738                 rcu_assign_pointer(nf_nat_protos[i], &nf_nat_unknown_protocol);
 739         rcu_assign_pointer(nf_nat_protos[IPPROTO_TCP], &nf_nat_protocol_tcp);
 740         rcu_assign_pointer(nf_nat_protos[IPPROTO_UDP], &nf_nat_protocol_udp);
 741         rcu_assign_pointer(nf_nat_protos[IPPROTO_ICMP], &nf_nat_protocol_icmp);
 742         spin_unlock_bh(&nf_nat_lock);
 743
 744         /* Initialize fake conntrack so that NAT will skip it */
 745         nf_conntrack_untracked.status |= IPS_NAT_DONE_MASK;
 746
 747         l3proto = nf_ct_l3proto_find_get((u_int16_t)AF_INET);
 748
 749         BUG_ON(nf_nat_seq_adjust_hook != NULL);
 750         rcu_assign_pointer(nf_nat_seq_adjust_hook, nf_nat_seq_adjust);
 751         BUG_ON(nfnetlink_parse_nat_setup_hook != NULL);
 752         rcu_assign_pointer(nfnetlink_parse_nat_setup_hook,
 753                            nfnetlink_parse_nat_setup);
 754         BUG_ON(nf_ct_nat_offset != NULL);
 755         rcu_assign_pointer(nf_ct_nat_offset, nf_nat_get_offset);
 756         return 0;
 757
 758  cleanup_extend:
 759         nf_ct_extend_unregister(&nat_extend);
 760         return ret;
 761 }
 762
 763 static void __exit nf_nat_cleanup(void)
 764 {
 765         unregister_pernet_subsys(&nf_nat_net_ops);
 766         nf_ct_l3proto_put(l3proto);
 767         nf_ct_extend_unregister(&nat_extend);
 768         rcu_assign_pointer(nf_nat_seq_adjust_hook, NULL);
 769         rcu_assign_pointer(nfnetlink_parse_nat_setup_hook, NULL);
 770         rcu_assign_pointer(nf_ct_nat_offset, NULL);
 771         synchronize_net();
 772 }
 773
 774 MODULE_LICENSE("GPL");
 775 MODULE_ALIAS("nf-nat-ipv4");
 776
 777 module_init(nf_nat_init);
 778 module_exit(nf_nat_cleanup);