linux/net/netfilter/nf_nat_core.c
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   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#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/xfrm.h>
  17#include <linux/jhash.h>
  18#include <linux/rtnetlink.h>
  19
  20#include <net/netfilter/nf_conntrack.h>
  21#include <net/netfilter/nf_conntrack_core.h>
  22#include <net/netfilter/nf_nat.h>
  23#include <net/netfilter/nf_nat_l3proto.h>
  24#include <net/netfilter/nf_nat_l4proto.h>
  25#include <net/netfilter/nf_nat_core.h>
  26#include <net/netfilter/nf_nat_helper.h>
  27#include <net/netfilter/nf_conntrack_helper.h>
  28#include <net/netfilter/nf_conntrack_l3proto.h>
  29#include <net/netfilter/nf_conntrack_zones.h>
  30#include <linux/netfilter/nf_nat.h>
  31
  32static DEFINE_SPINLOCK(nf_nat_lock);
  33
  34static DEFINE_MUTEX(nf_nat_proto_mutex);
  35static const struct nf_nat_l3proto __rcu *nf_nat_l3protos[NFPROTO_NUMPROTO]
  36                                                __read_mostly;
  37static const struct nf_nat_l4proto __rcu **nf_nat_l4protos[NFPROTO_NUMPROTO]
  38                                                __read_mostly;
  39
  40
  41inline const struct nf_nat_l3proto *
  42__nf_nat_l3proto_find(u8 family)
  43{
  44        return rcu_dereference(nf_nat_l3protos[family]);
  45}
  46
  47inline const struct nf_nat_l4proto *
  48__nf_nat_l4proto_find(u8 family, u8 protonum)
  49{
  50        return rcu_dereference(nf_nat_l4protos[family][protonum]);
  51}
  52EXPORT_SYMBOL_GPL(__nf_nat_l4proto_find);
  53
  54#ifdef CONFIG_XFRM
  55static void __nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl)
  56{
  57        const struct nf_nat_l3proto *l3proto;
  58        const struct nf_conn *ct;
  59        enum ip_conntrack_info ctinfo;
  60        enum ip_conntrack_dir dir;
  61        unsigned  long statusbit;
  62        u8 family;
  63
  64        ct = nf_ct_get(skb, &ctinfo);
  65        if (ct == NULL)
  66                return;
  67
  68        family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
  69        rcu_read_lock();
  70        l3proto = __nf_nat_l3proto_find(family);
  71        if (l3proto == NULL)
  72                goto out;
  73
  74        dir = CTINFO2DIR(ctinfo);
  75        if (dir == IP_CT_DIR_ORIGINAL)
  76                statusbit = IPS_DST_NAT;
  77        else
  78                statusbit = IPS_SRC_NAT;
  79
  80        l3proto->decode_session(skb, ct, dir, statusbit, fl);
  81out:
  82        rcu_read_unlock();
  83}
  84
  85int nf_xfrm_me_harder(struct sk_buff *skb, unsigned int family)
  86{
  87        struct flowi fl;
  88        unsigned int hh_len;
  89        struct dst_entry *dst;
  90        int err;
  91
  92        err = xfrm_decode_session(skb, &fl, family);
  93        if (err < 0)
  94                return err;
  95
  96        dst = skb_dst(skb);
  97        if (dst->xfrm)
  98                dst = ((struct xfrm_dst *)dst)->route;
  99        dst_hold(dst);
 100
 101        dst = xfrm_lookup(dev_net(dst->dev), dst, &fl, skb->sk, 0);
 102        if (IS_ERR(dst))
 103                return PTR_ERR(dst);
 104
 105        skb_dst_drop(skb);
 106        skb_dst_set(skb, dst);
 107
 108        /* Change in oif may mean change in hh_len. */
 109        hh_len = skb_dst(skb)->dev->hard_header_len;
 110        if (skb_headroom(skb) < hh_len &&
 111            pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
 112                return -ENOMEM;
 113        return 0;
 114}
 115EXPORT_SYMBOL(nf_xfrm_me_harder);
 116#endif /* CONFIG_XFRM */
 117
 118/* We keep an extra hash for each conntrack, for fast searching. */
 119static inline unsigned int
 120hash_by_src(const struct net *net, u16 zone,
 121            const struct nf_conntrack_tuple *tuple)
 122{
 123        unsigned int hash;
 124
 125        /* Original src, to ensure we map it consistently if poss. */
 126        hash = jhash2((u32 *)&tuple->src, sizeof(tuple->src) / sizeof(u32),
 127                      tuple->dst.protonum ^ zone ^ nf_conntrack_hash_rnd);
 128        return ((u64)hash * net->ct.nat_htable_size) >> 32;
 129}
 130
 131/* Is this tuple already taken? (not by us) */
 132int
 133nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple,
 134                  const struct nf_conn *ignored_conntrack)
 135{
 136        /* Conntrack tracking doesn't keep track of outgoing tuples; only
 137         * incoming ones.  NAT means they don't have a fixed mapping,
 138         * so we invert the tuple and look for the incoming reply.
 139         *
 140         * We could keep a separate hash if this proves too slow.
 141         */
 142        struct nf_conntrack_tuple reply;
 143
 144        nf_ct_invert_tuplepr(&reply, tuple);
 145        return nf_conntrack_tuple_taken(&reply, ignored_conntrack);
 146}
 147EXPORT_SYMBOL(nf_nat_used_tuple);
 148
 149/* If we source map this tuple so reply looks like reply_tuple, will
 150 * that meet the constraints of range.
 151 */
 152static int in_range(const struct nf_nat_l3proto *l3proto,
 153                    const struct nf_nat_l4proto *l4proto,
 154                    const struct nf_conntrack_tuple *tuple,
 155                    const struct nf_nat_range *range)
 156{
 157        /* If we are supposed to map IPs, then we must be in the
 158         * range specified, otherwise let this drag us onto a new src IP.
 159         */
 160        if (range->flags & NF_NAT_RANGE_MAP_IPS &&
 161            !l3proto->in_range(tuple, range))
 162                return 0;
 163
 164        if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) ||
 165            l4proto->in_range(tuple, NF_NAT_MANIP_SRC,
 166                              &range->min_proto, &range->max_proto))
 167                return 1;
 168
 169        return 0;
 170}
 171
 172static inline int
 173same_src(const struct nf_conn *ct,
 174         const struct nf_conntrack_tuple *tuple)
 175{
 176        const struct nf_conntrack_tuple *t;
 177
 178        t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
 179        return (t->dst.protonum == tuple->dst.protonum &&
 180                nf_inet_addr_cmp(&t->src.u3, &tuple->src.u3) &&
 181                t->src.u.all == tuple->src.u.all);
 182}
 183
 184/* Only called for SRC manip */
 185static int
 186find_appropriate_src(struct net *net, u16 zone,
 187                     const struct nf_nat_l3proto *l3proto,
 188                     const struct nf_nat_l4proto *l4proto,
 189                     const struct nf_conntrack_tuple *tuple,
 190                     struct nf_conntrack_tuple *result,
 191                     const struct nf_nat_range *range)
 192{
 193        unsigned int h = hash_by_src(net, zone, tuple);
 194        const struct nf_conn_nat *nat;
 195        const struct nf_conn *ct;
 196
 197        hlist_for_each_entry_rcu(nat, &net->ct.nat_bysource[h], bysource) {
 198                ct = nat->ct;
 199                if (same_src(ct, tuple) && nf_ct_zone(ct) == zone) {
 200                        /* Copy source part from reply tuple. */
 201                        nf_ct_invert_tuplepr(result,
 202                                       &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
 203                        result->dst = tuple->dst;
 204
 205                        if (in_range(l3proto, l4proto, result, range))
 206                                return 1;
 207                }
 208        }
 209        return 0;
 210}
 211
 212/* For [FUTURE] fragmentation handling, we want the least-used
 213 * src-ip/dst-ip/proto triple.  Fairness doesn't come into it.  Thus
 214 * if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports
 215 * 1-65535, we don't do pro-rata allocation based on ports; we choose
 216 * the ip with the lowest src-ip/dst-ip/proto usage.
 217 */
 218static void
 219find_best_ips_proto(u16 zone, struct nf_conntrack_tuple *tuple,
 220                    const struct nf_nat_range *range,
 221                    const struct nf_conn *ct,
 222                    enum nf_nat_manip_type maniptype)
 223{
 224        union nf_inet_addr *var_ipp;
 225        unsigned int i, max;
 226        /* Host order */
 227        u32 minip, maxip, j, dist;
 228        bool full_range;
 229
 230        /* No IP mapping?  Do nothing. */
 231        if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
 232                return;
 233
 234        if (maniptype == NF_NAT_MANIP_SRC)
 235                var_ipp = &tuple->src.u3;
 236        else
 237                var_ipp = &tuple->dst.u3;
 238
 239        /* Fast path: only one choice. */
 240        if (nf_inet_addr_cmp(&range->min_addr, &range->max_addr)) {
 241                *var_ipp = range->min_addr;
 242                return;
 243        }
 244
 245        if (nf_ct_l3num(ct) == NFPROTO_IPV4)
 246                max = sizeof(var_ipp->ip) / sizeof(u32) - 1;
 247        else
 248                max = sizeof(var_ipp->ip6) / sizeof(u32) - 1;
 249
 250        /* Hashing source and destination IPs gives a fairly even
 251         * spread in practice (if there are a small number of IPs
 252         * involved, there usually aren't that many connections
 253         * anyway).  The consistency means that servers see the same
 254         * client coming from the same IP (some Internet Banking sites
 255         * like this), even across reboots.
 256         */
 257        j = jhash2((u32 *)&tuple->src.u3, sizeof(tuple->src.u3) / sizeof(u32),
 258                   range->flags & NF_NAT_RANGE_PERSISTENT ?
 259                        0 : (__force u32)tuple->dst.u3.all[max] ^ zone);
 260
 261        full_range = false;
 262        for (i = 0; i <= max; i++) {
 263                /* If first bytes of the address are at the maximum, use the
 264                 * distance. Otherwise use the full range.
 265                 */
 266                if (!full_range) {
 267                        minip = ntohl((__force __be32)range->min_addr.all[i]);
 268                        maxip = ntohl((__force __be32)range->max_addr.all[i]);
 269                        dist  = maxip - minip + 1;
 270                } else {
 271                        minip = 0;
 272                        dist  = ~0;
 273                }
 274
 275                var_ipp->all[i] = (__force __u32)
 276                        htonl(minip + (((u64)j * dist) >> 32));
 277                if (var_ipp->all[i] != range->max_addr.all[i])
 278                        full_range = true;
 279
 280                if (!(range->flags & NF_NAT_RANGE_PERSISTENT))
 281                        j ^= (__force u32)tuple->dst.u3.all[i];
 282        }
 283}
 284
 285/* Manipulate the tuple into the range given. For NF_INET_POST_ROUTING,
 286 * we change the source to map into the range. For NF_INET_PRE_ROUTING
 287 * and NF_INET_LOCAL_OUT, we change the destination to map into the
 288 * range. It might not be possible to get a unique tuple, but we try.
 289 * At worst (or if we race), we will end up with a final duplicate in
 290 * __ip_conntrack_confirm and drop the packet. */
 291static void
 292get_unique_tuple(struct nf_conntrack_tuple *tuple,
 293                 const struct nf_conntrack_tuple *orig_tuple,
 294                 const struct nf_nat_range *range,
 295                 struct nf_conn *ct,
 296                 enum nf_nat_manip_type maniptype)
 297{
 298        const struct nf_nat_l3proto *l3proto;
 299        const struct nf_nat_l4proto *l4proto;
 300        struct net *net = nf_ct_net(ct);
 301        u16 zone = nf_ct_zone(ct);
 302
 303        rcu_read_lock();
 304        l3proto = __nf_nat_l3proto_find(orig_tuple->src.l3num);
 305        l4proto = __nf_nat_l4proto_find(orig_tuple->src.l3num,
 306                                        orig_tuple->dst.protonum);
 307
 308        /* 1) If this srcip/proto/src-proto-part is currently mapped,
 309         * and that same mapping gives a unique tuple within the given
 310         * range, use that.
 311         *
 312         * This is only required for source (ie. NAT/masq) mappings.
 313         * So far, we don't do local source mappings, so multiple
 314         * manips not an issue.
 315         */
 316        if (maniptype == NF_NAT_MANIP_SRC &&
 317            !(range->flags & NF_NAT_RANGE_PROTO_RANDOM)) {
 318                /* try the original tuple first */
 319                if (in_range(l3proto, l4proto, orig_tuple, range)) {
 320                        if (!nf_nat_used_tuple(orig_tuple, ct)) {
 321                                *tuple = *orig_tuple;
 322                                goto out;
 323                        }
 324                } else if (find_appropriate_src(net, zone, l3proto, l4proto,
 325                                                orig_tuple, tuple, range)) {
 326                        pr_debug("get_unique_tuple: Found current src map\n");
 327                        if (!nf_nat_used_tuple(tuple, ct))
 328                                goto out;
 329                }
 330        }
 331
 332        /* 2) Select the least-used IP/proto combination in the given range */
 333        *tuple = *orig_tuple;
 334        find_best_ips_proto(zone, tuple, range, ct, maniptype);
 335
 336        /* 3) The per-protocol part of the manip is made to map into
 337         * the range to make a unique tuple.
 338         */
 339
 340        /* Only bother mapping if it's not already in range and unique */
 341        if (!(range->flags & NF_NAT_RANGE_PROTO_RANDOM)) {
 342                if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
 343                        if (l4proto->in_range(tuple, maniptype,
 344                                              &range->min_proto,
 345                                              &range->max_proto) &&
 346                            (range->min_proto.all == range->max_proto.all ||
 347                             !nf_nat_used_tuple(tuple, ct)))
 348                                goto out;
 349                } else if (!nf_nat_used_tuple(tuple, ct)) {
 350                        goto out;
 351                }
 352        }
 353
 354        /* Last change: get protocol to try to obtain unique tuple. */
 355        l4proto->unique_tuple(l3proto, tuple, range, maniptype, ct);
 356out:
 357        rcu_read_unlock();
 358}
 359
 360unsigned int
 361nf_nat_setup_info(struct nf_conn *ct,
 362                  const struct nf_nat_range *range,
 363                  enum nf_nat_manip_type maniptype)
 364{
 365        struct net *net = nf_ct_net(ct);
 366        struct nf_conntrack_tuple curr_tuple, new_tuple;
 367        struct nf_conn_nat *nat;
 368
 369        /* nat helper or nfctnetlink also setup binding */
 370        nat = nfct_nat(ct);
 371        if (!nat) {
 372                nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
 373                if (nat == NULL) {
 374                        pr_debug("failed to add NAT extension\n");
 375                        return NF_ACCEPT;
 376                }
 377        }
 378
 379        NF_CT_ASSERT(maniptype == NF_NAT_MANIP_SRC ||
 380                     maniptype == NF_NAT_MANIP_DST);
 381        BUG_ON(nf_nat_initialized(ct, maniptype));
 382
 383        /* What we've got will look like inverse of reply. Normally
 384         * this is what is in the conntrack, except for prior
 385         * manipulations (future optimization: if num_manips == 0,
 386         * orig_tp = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple)
 387         */
 388        nf_ct_invert_tuplepr(&curr_tuple,
 389                             &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
 390
 391        get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype);
 392
 393        if (!nf_ct_tuple_equal(&new_tuple, &curr_tuple)) {
 394                struct nf_conntrack_tuple reply;
 395
 396                /* Alter conntrack table so will recognize replies. */
 397                nf_ct_invert_tuplepr(&reply, &new_tuple);
 398                nf_conntrack_alter_reply(ct, &reply);
 399
 400                /* Non-atomic: we own this at the moment. */
 401                if (maniptype == NF_NAT_MANIP_SRC)
 402                        ct->status |= IPS_SRC_NAT;
 403                else
 404                        ct->status |= IPS_DST_NAT;
 405        }
 406
 407        if (maniptype == NF_NAT_MANIP_SRC) {
 408                unsigned int srchash;
 409
 410                srchash = hash_by_src(net, nf_ct_zone(ct),
 411                                      &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
 412                spin_lock_bh(&nf_nat_lock);
 413                /* nf_conntrack_alter_reply might re-allocate extension aera */
 414                nat = nfct_nat(ct);
 415                nat->ct = ct;
 416                hlist_add_head_rcu(&nat->bysource,
 417                                   &net->ct.nat_bysource[srchash]);
 418                spin_unlock_bh(&nf_nat_lock);
 419        }
 420
 421        /* It's done. */
 422        if (maniptype == NF_NAT_MANIP_DST)
 423                ct->status |= IPS_DST_NAT_DONE;
 424        else
 425                ct->status |= IPS_SRC_NAT_DONE;
 426
 427        return NF_ACCEPT;
 428}
 429EXPORT_SYMBOL(nf_nat_setup_info);
 430
 431/* Do packet manipulations according to nf_nat_setup_info. */
 432unsigned int nf_nat_packet(struct nf_conn *ct,
 433                           enum ip_conntrack_info ctinfo,
 434                           unsigned int hooknum,
 435                           struct sk_buff *skb)
 436{
 437        const struct nf_nat_l3proto *l3proto;
 438        const struct nf_nat_l4proto *l4proto;
 439        enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 440        unsigned long statusbit;
 441        enum nf_nat_manip_type mtype = HOOK2MANIP(hooknum);
 442
 443        if (mtype == NF_NAT_MANIP_SRC)
 444                statusbit = IPS_SRC_NAT;
 445        else
 446                statusbit = IPS_DST_NAT;
 447
 448        /* Invert if this is reply dir. */
 449        if (dir == IP_CT_DIR_REPLY)
 450                statusbit ^= IPS_NAT_MASK;
 451
 452        /* Non-atomic: these bits don't change. */
 453        if (ct->status & statusbit) {
 454                struct nf_conntrack_tuple target;
 455
 456                /* We are aiming to look like inverse of other direction. */
 457                nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
 458
 459                l3proto = __nf_nat_l3proto_find(target.src.l3num);
 460                l4proto = __nf_nat_l4proto_find(target.src.l3num,
 461                                                target.dst.protonum);
 462                if (!l3proto->manip_pkt(skb, 0, l4proto, &target, mtype))
 463                        return NF_DROP;
 464        }
 465        return NF_ACCEPT;
 466}
 467EXPORT_SYMBOL_GPL(nf_nat_packet);
 468
 469struct nf_nat_proto_clean {
 470        u8      l3proto;
 471        u8      l4proto;
 472};
 473
 474/* kill conntracks with affected NAT section */
 475static int nf_nat_proto_remove(struct nf_conn *i, void *data)
 476{
 477        const struct nf_nat_proto_clean *clean = data;
 478        struct nf_conn_nat *nat = nfct_nat(i);
 479
 480        if (!nat)
 481                return 0;
 482
 483        if ((clean->l3proto && nf_ct_l3num(i) != clean->l3proto) ||
 484            (clean->l4proto && nf_ct_protonum(i) != clean->l4proto))
 485                return 0;
 486
 487        return i->status & IPS_NAT_MASK ? 1 : 0;
 488}
 489
 490static void nf_nat_l4proto_clean(u8 l3proto, u8 l4proto)
 491{
 492        struct nf_nat_proto_clean clean = {
 493                .l3proto = l3proto,
 494                .l4proto = l4proto,
 495        };
 496        struct net *net;
 497
 498        rtnl_lock();
 499        for_each_net(net)
 500                nf_ct_iterate_cleanup(net, nf_nat_proto_remove, &clean);
 501        rtnl_unlock();
 502}
 503
 504static void nf_nat_l3proto_clean(u8 l3proto)
 505{
 506        struct nf_nat_proto_clean clean = {
 507                .l3proto = l3proto,
 508        };
 509        struct net *net;
 510
 511        rtnl_lock();
 512
 513        for_each_net(net)
 514                nf_ct_iterate_cleanup(net, nf_nat_proto_remove, &clean);
 515        rtnl_unlock();
 516}
 517
 518/* Protocol registration. */
 519int nf_nat_l4proto_register(u8 l3proto, const struct nf_nat_l4proto *l4proto)
 520{
 521        const struct nf_nat_l4proto **l4protos;
 522        unsigned int i;
 523        int ret = 0;
 524
 525        mutex_lock(&nf_nat_proto_mutex);
 526        if (nf_nat_l4protos[l3proto] == NULL) {
 527                l4protos = kmalloc(IPPROTO_MAX * sizeof(struct nf_nat_l4proto *),
 528                                   GFP_KERNEL);
 529                if (l4protos == NULL) {
 530                        ret = -ENOMEM;
 531                        goto out;
 532                }
 533
 534                for (i = 0; i < IPPROTO_MAX; i++)
 535                        RCU_INIT_POINTER(l4protos[i], &nf_nat_l4proto_unknown);
 536
 537                /* Before making proto_array visible to lockless readers,
 538                 * we must make sure its content is committed to memory.
 539                 */
 540                smp_wmb();
 541
 542                nf_nat_l4protos[l3proto] = l4protos;
 543        }
 544
 545        if (rcu_dereference_protected(
 546                        nf_nat_l4protos[l3proto][l4proto->l4proto],
 547                        lockdep_is_held(&nf_nat_proto_mutex)
 548                        ) != &nf_nat_l4proto_unknown) {
 549                ret = -EBUSY;
 550                goto out;
 551        }
 552        RCU_INIT_POINTER(nf_nat_l4protos[l3proto][l4proto->l4proto], l4proto);
 553 out:
 554        mutex_unlock(&nf_nat_proto_mutex);
 555        return ret;
 556}
 557EXPORT_SYMBOL_GPL(nf_nat_l4proto_register);
 558
 559/* No one stores the protocol anywhere; simply delete it. */
 560void nf_nat_l4proto_unregister(u8 l3proto, const struct nf_nat_l4proto *l4proto)
 561{
 562        mutex_lock(&nf_nat_proto_mutex);
 563        RCU_INIT_POINTER(nf_nat_l4protos[l3proto][l4proto->l4proto],
 564                         &nf_nat_l4proto_unknown);
 565        mutex_unlock(&nf_nat_proto_mutex);
 566        synchronize_rcu();
 567
 568        nf_nat_l4proto_clean(l3proto, l4proto->l4proto);
 569}
 570EXPORT_SYMBOL_GPL(nf_nat_l4proto_unregister);
 571
 572int nf_nat_l3proto_register(const struct nf_nat_l3proto *l3proto)
 573{
 574        int err;
 575
 576        err = nf_ct_l3proto_try_module_get(l3proto->l3proto);
 577        if (err < 0)
 578                return err;
 579
 580        mutex_lock(&nf_nat_proto_mutex);
 581        RCU_INIT_POINTER(nf_nat_l4protos[l3proto->l3proto][IPPROTO_TCP],
 582                         &nf_nat_l4proto_tcp);
 583        RCU_INIT_POINTER(nf_nat_l4protos[l3proto->l3proto][IPPROTO_UDP],
 584                         &nf_nat_l4proto_udp);
 585        mutex_unlock(&nf_nat_proto_mutex);
 586
 587        RCU_INIT_POINTER(nf_nat_l3protos[l3proto->l3proto], l3proto);
 588        return 0;
 589}
 590EXPORT_SYMBOL_GPL(nf_nat_l3proto_register);
 591
 592void nf_nat_l3proto_unregister(const struct nf_nat_l3proto *l3proto)
 593{
 594        mutex_lock(&nf_nat_proto_mutex);
 595        RCU_INIT_POINTER(nf_nat_l3protos[l3proto->l3proto], NULL);
 596        mutex_unlock(&nf_nat_proto_mutex);
 597        synchronize_rcu();
 598
 599        nf_nat_l3proto_clean(l3proto->l3proto);
 600        nf_ct_l3proto_module_put(l3proto->l3proto);
 601}
 602EXPORT_SYMBOL_GPL(nf_nat_l3proto_unregister);
 603
 604/* No one using conntrack by the time this called. */
 605static void nf_nat_cleanup_conntrack(struct nf_conn *ct)
 606{
 607        struct nf_conn_nat *nat = nf_ct_ext_find(ct, NF_CT_EXT_NAT);
 608
 609        if (nat == NULL || nat->ct == NULL)
 610                return;
 611
 612        NF_CT_ASSERT(nat->ct->status & IPS_SRC_NAT_DONE);
 613
 614        spin_lock_bh(&nf_nat_lock);
 615        hlist_del_rcu(&nat->bysource);
 616        spin_unlock_bh(&nf_nat_lock);
 617}
 618
 619static void nf_nat_move_storage(void *new, void *old)
 620{
 621        struct nf_conn_nat *new_nat = new;
 622        struct nf_conn_nat *old_nat = old;
 623        struct nf_conn *ct = old_nat->ct;
 624
 625        if (!ct || !(ct->status & IPS_SRC_NAT_DONE))
 626                return;
 627
 628        spin_lock_bh(&nf_nat_lock);
 629        hlist_replace_rcu(&old_nat->bysource, &new_nat->bysource);
 630        spin_unlock_bh(&nf_nat_lock);
 631}
 632
 633static struct nf_ct_ext_type nat_extend __read_mostly = {
 634        .len            = sizeof(struct nf_conn_nat),
 635        .align          = __alignof__(struct nf_conn_nat),
 636        .destroy        = nf_nat_cleanup_conntrack,
 637        .move           = nf_nat_move_storage,
 638        .id             = NF_CT_EXT_NAT,
 639        .flags          = NF_CT_EXT_F_PREALLOC,
 640};
 641
 642#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 643
 644#include <linux/netfilter/nfnetlink.h>
 645#include <linux/netfilter/nfnetlink_conntrack.h>
 646
 647static const struct nla_policy protonat_nla_policy[CTA_PROTONAT_MAX+1] = {
 648        [CTA_PROTONAT_PORT_MIN] = { .type = NLA_U16 },
 649        [CTA_PROTONAT_PORT_MAX] = { .type = NLA_U16 },
 650};
 651
 652static int nfnetlink_parse_nat_proto(struct nlattr *attr,
 653                                     const struct nf_conn *ct,
 654                                     struct nf_nat_range *range)
 655{
 656        struct nlattr *tb[CTA_PROTONAT_MAX+1];
 657        const struct nf_nat_l4proto *l4proto;
 658        int err;
 659
 660        err = nla_parse_nested(tb, CTA_PROTONAT_MAX, attr, protonat_nla_policy);
 661        if (err < 0)
 662                return err;
 663
 664        l4proto = __nf_nat_l4proto_find(nf_ct_l3num(ct), nf_ct_protonum(ct));
 665        if (l4proto->nlattr_to_range)
 666                err = l4proto->nlattr_to_range(tb, range);
 667
 668        return err;
 669}
 670
 671static const struct nla_policy nat_nla_policy[CTA_NAT_MAX+1] = {
 672        [CTA_NAT_V4_MINIP]      = { .type = NLA_U32 },
 673        [CTA_NAT_V4_MAXIP]      = { .type = NLA_U32 },
 674        [CTA_NAT_V6_MINIP]      = { .len = sizeof(struct in6_addr) },
 675        [CTA_NAT_V6_MAXIP]      = { .len = sizeof(struct in6_addr) },
 676        [CTA_NAT_PROTO]         = { .type = NLA_NESTED },
 677};
 678
 679static int
 680nfnetlink_parse_nat(const struct nlattr *nat,
 681                    const struct nf_conn *ct, struct nf_nat_range *range)
 682{
 683        const struct nf_nat_l3proto *l3proto;
 684        struct nlattr *tb[CTA_NAT_MAX+1];
 685        int err;
 686
 687        memset(range, 0, sizeof(*range));
 688
 689        err = nla_parse_nested(tb, CTA_NAT_MAX, nat, nat_nla_policy);
 690        if (err < 0)
 691                return err;
 692
 693        rcu_read_lock();
 694        l3proto = __nf_nat_l3proto_find(nf_ct_l3num(ct));
 695        if (l3proto == NULL) {
 696                err = -EAGAIN;
 697                goto out;
 698        }
 699        err = l3proto->nlattr_to_range(tb, range);
 700        if (err < 0)
 701                goto out;
 702
 703        if (!tb[CTA_NAT_PROTO])
 704                goto out;
 705
 706        err = nfnetlink_parse_nat_proto(tb[CTA_NAT_PROTO], ct, range);
 707out:
 708        rcu_read_unlock();
 709        return err;
 710}
 711
 712static int
 713nfnetlink_parse_nat_setup(struct nf_conn *ct,
 714                          enum nf_nat_manip_type manip,
 715                          const struct nlattr *attr)
 716{
 717        struct nf_nat_range range;
 718        int err;
 719
 720        err = nfnetlink_parse_nat(attr, ct, &range);
 721        if (err < 0)
 722                return err;
 723        if (nf_nat_initialized(ct, manip))
 724                return -EEXIST;
 725
 726        return nf_nat_setup_info(ct, &range, manip);
 727}
 728#else
 729static int
 730nfnetlink_parse_nat_setup(struct nf_conn *ct,
 731                          enum nf_nat_manip_type manip,
 732                          const struct nlattr *attr)
 733{
 734        return -EOPNOTSUPP;
 735}
 736#endif
 737
 738static int __net_init nf_nat_net_init(struct net *net)
 739{
 740        /* Leave them the same for the moment. */
 741        net->ct.nat_htable_size = net->ct.htable_size;
 742        net->ct.nat_bysource = nf_ct_alloc_hashtable(&net->ct.nat_htable_size, 0);
 743        if (!net->ct.nat_bysource)
 744                return -ENOMEM;
 745        return 0;
 746}
 747
 748static void __net_exit nf_nat_net_exit(struct net *net)
 749{
 750        struct nf_nat_proto_clean clean = {};
 751
 752        nf_ct_iterate_cleanup(net, &nf_nat_proto_remove, &clean);
 753        synchronize_rcu();
 754        nf_ct_free_hashtable(net->ct.nat_bysource, net->ct.nat_htable_size);
 755}
 756
 757static struct pernet_operations nf_nat_net_ops = {
 758        .init = nf_nat_net_init,
 759        .exit = nf_nat_net_exit,
 760};
 761
 762static struct nf_ct_helper_expectfn follow_master_nat = {
 763        .name           = "nat-follow-master",
 764        .expectfn       = nf_nat_follow_master,
 765};
 766
 767static struct nfq_ct_nat_hook nfq_ct_nat = {
 768        .seq_adjust     = nf_nat_tcp_seq_adjust,
 769};
 770
 771static int __init nf_nat_init(void)
 772{
 773        int ret;
 774
 775        ret = nf_ct_extend_register(&nat_extend);
 776        if (ret < 0) {
 777                printk(KERN_ERR "nf_nat_core: Unable to register extension\n");
 778                return ret;
 779        }
 780
 781        ret = register_pernet_subsys(&nf_nat_net_ops);
 782        if (ret < 0)
 783                goto cleanup_extend;
 784
 785        nf_ct_helper_expectfn_register(&follow_master_nat);
 786
 787        /* Initialize fake conntrack so that NAT will skip it */
 788        nf_ct_untracked_status_or(IPS_NAT_DONE_MASK);
 789
 790        BUG_ON(nf_nat_seq_adjust_hook != NULL);
 791        RCU_INIT_POINTER(nf_nat_seq_adjust_hook, nf_nat_seq_adjust);
 792        BUG_ON(nfnetlink_parse_nat_setup_hook != NULL);
 793        RCU_INIT_POINTER(nfnetlink_parse_nat_setup_hook,
 794                           nfnetlink_parse_nat_setup);
 795        BUG_ON(nf_ct_nat_offset != NULL);
 796        RCU_INIT_POINTER(nf_ct_nat_offset, nf_nat_get_offset);
 797        RCU_INIT_POINTER(nfq_ct_nat_hook, &nfq_ct_nat);
 798#ifdef CONFIG_XFRM
 799        BUG_ON(nf_nat_decode_session_hook != NULL);
 800        RCU_INIT_POINTER(nf_nat_decode_session_hook, __nf_nat_decode_session);
 801#endif
 802        return 0;
 803
 804 cleanup_extend:
 805        nf_ct_extend_unregister(&nat_extend);
 806        return ret;
 807}
 808
 809static void __exit nf_nat_cleanup(void)
 810{
 811        unsigned int i;
 812
 813        unregister_pernet_subsys(&nf_nat_net_ops);
 814        nf_ct_extend_unregister(&nat_extend);
 815        nf_ct_helper_expectfn_unregister(&follow_master_nat);
 816        RCU_INIT_POINTER(nf_nat_seq_adjust_hook, NULL);
 817        RCU_INIT_POINTER(nfnetlink_parse_nat_setup_hook, NULL);
 818        RCU_INIT_POINTER(nf_ct_nat_offset, NULL);
 819        RCU_INIT_POINTER(nfq_ct_nat_hook, NULL);
 820#ifdef CONFIG_XFRM
 821        RCU_INIT_POINTER(nf_nat_decode_session_hook, NULL);
 822#endif
 823        for (i = 0; i < NFPROTO_NUMPROTO; i++)
 824                kfree(nf_nat_l4protos[i]);
 825        synchronize_net();
 826}
 827
 828MODULE_LICENSE("GPL");
 829
 830module_init(nf_nat_init);
 831module_exit(nf_nat_cleanup);
 832
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