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