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/siphash.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 siphash_aligned_key_t nf_nat_hash_rnd;
  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 *net,
 154             const struct nf_conntrack_zone *zone,
 155             const struct nf_conntrack_tuple *tuple)
 156 {
 157         unsigned int hash;
 158         struct {
 159                 struct nf_conntrack_man src;
 160                 u32 net_mix;
 161                 u32 protonum;
 162                 u32 zone;
 163         } __aligned(SIPHASH_ALIGNMENT) combined;
 164
 165         get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd));
 166
 167         memset(&combined, 0, sizeof(combined));
 168
 169         /* Original src, to ensure we map it consistently if poss. */
 170         combined.src = tuple->src;
 171         combined.net_mix = net_hash_mix(net);
 172         combined.protonum = tuple->dst.protonum;
 173
 174         /* Zone ID can be used provided its valid for both directions */
 175         if (zone->dir == NF_CT_DEFAULT_ZONE_DIR)
 176                 combined.zone = zone->id;
 177
 178         hash = siphash(&combined, sizeof(combined), &nf_nat_hash_rnd);
 179
 180         return reciprocal_scale(hash, nf_nat_htable_size);
 181 }
 182
 183 /* Is this tuple already taken? (not by us) */
 184 static int
 185 nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple,
 186                   const struct nf_conn *ignored_conntrack)
 187 {
 188         /* Conntrack tracking doesn't keep track of outgoing tuples; only
 189          * incoming ones.  NAT means they don't have a fixed mapping,
 190          * so we invert the tuple and look for the incoming reply.
 191          *
 192          * We could keep a separate hash if this proves too slow.
 193          */
 194         struct nf_conntrack_tuple reply;
 195
 196         nf_ct_invert_tuple(&reply, tuple);
 197         return nf_conntrack_tuple_taken(&reply, ignored_conntrack);
 198 }
 199
 200 static bool nf_nat_inet_in_range(const struct nf_conntrack_tuple *t,
 201                                  const struct nf_nat_range2 *range)
 202 {
 203         if (t->src.l3num == NFPROTO_IPV4)
 204                 return ntohl(t->src.u3.ip) >= ntohl(range->min_addr.ip) &&
 205                        ntohl(t->src.u3.ip) <= ntohl(range->max_addr.ip);
 206
 207         return ipv6_addr_cmp(&t->src.u3.in6, &range->min_addr.in6) >= 0 &&
 208                ipv6_addr_cmp(&t->src.u3.in6, &range->max_addr.in6) <= 0;
 209 }
 210
 211 /* Is the manipable part of the tuple between min and max incl? */
 212 static bool l4proto_in_range(const struct nf_conntrack_tuple *tuple,
 213                              enum nf_nat_manip_type maniptype,
 214                              const union nf_conntrack_man_proto *min,
 215                              const union nf_conntrack_man_proto *max)
 216 {
 217         __be16 port;
 218
 219         switch (tuple->dst.protonum) {
 220         case IPPROTO_ICMP:
 221         case IPPROTO_ICMPV6:
 222                 return ntohs(tuple->src.u.icmp.id) >= ntohs(min->icmp.id) &&
 223                        ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id);
 224         case IPPROTO_GRE: /* all fall though */
 225         case IPPROTO_TCP:
 226         case IPPROTO_UDP:
 227         case IPPROTO_UDPLITE:
 228         case IPPROTO_DCCP:
 229         case IPPROTO_SCTP:
 230                 if (maniptype == NF_NAT_MANIP_SRC)
 231                         port = tuple->src.u.all;
 232                 else
 233                         port = tuple->dst.u.all;
 234
 235                 return ntohs(port) >= ntohs(min->all) &&
 236                        ntohs(port) <= ntohs(max->all);
 237         default:
 238                 return true;
 239         }
 240 }
 241
 242 /* If we source map this tuple so reply looks like reply_tuple, will
 243  * that meet the constraints of range.
 244  */
 245 static int in_range(const struct nf_conntrack_tuple *tuple,
 246                     const struct nf_nat_range2 *range)
 247 {
 248         /* If we are supposed to map IPs, then we must be in the
 249          * range specified, otherwise let this drag us onto a new src IP.
 250          */
 251         if (range->flags & NF_NAT_RANGE_MAP_IPS &&
 252             !nf_nat_inet_in_range(tuple, range))
 253                 return 0;
 254
 255         if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED))
 256                 return 1;
 257
 258         return l4proto_in_range(tuple, NF_NAT_MANIP_SRC,
 259                                 &range->min_proto, &range->max_proto);
 260 }
 261
 262 static inline int
 263 same_src(const struct nf_conn *ct,
 264          const struct nf_conntrack_tuple *tuple)
 265 {
 266         const struct nf_conntrack_tuple *t;
 267
 268         t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
 269         return (t->dst.protonum == tuple->dst.protonum &&
 270                 nf_inet_addr_cmp(&t->src.u3, &tuple->src.u3) &&
 271                 t->src.u.all == tuple->src.u.all);
 272 }
 273
 274 /* Only called for SRC manip */
 275 static int
 276 find_appropriate_src(struct net *net,
 277                      const struct nf_conntrack_zone *zone,
 278                      const struct nf_conntrack_tuple *tuple,
 279                      struct nf_conntrack_tuple *result,
 280                      const struct nf_nat_range2 *range)
 281 {
 282         unsigned int h = hash_by_src(net, zone, tuple);
 283         const struct nf_conn *ct;
 284
 285         hlist_for_each_entry_rcu(ct, &nf_nat_bysource[h], nat_bysource) {
 286                 if (same_src(ct, tuple) &&
 287                     net_eq(net, nf_ct_net(ct)) &&
 288                     nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL)) {
 289                         /* Copy source part from reply tuple. */
 290                         nf_ct_invert_tuple(result,
 291                                        &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
 292                         result->dst = tuple->dst;
 293
 294                         if (in_range(result, range))
 295                                 return 1;
 296                 }
 297         }
 298         return 0;
 299 }
 300
 301 /* For [FUTURE] fragmentation handling, we want the least-used
 302  * src-ip/dst-ip/proto triple.  Fairness doesn't come into it.  Thus
 303  * if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports
 304  * 1-65535, we don't do pro-rata allocation based on ports; we choose
 305  * the ip with the lowest src-ip/dst-ip/proto usage.
 306  */
 307 static void
 308 find_best_ips_proto(const struct nf_conntrack_zone *zone,
 309                     struct nf_conntrack_tuple *tuple,
 310                     const struct nf_nat_range2 *range,
 311                     const struct nf_conn *ct,
 312                     enum nf_nat_manip_type maniptype)
 313 {
 314         union nf_inet_addr *var_ipp;
 315         unsigned int i, max;
 316         /* Host order */
 317         u32 minip, maxip, j, dist;
 318         bool full_range;
 319
 320         /* No IP mapping?  Do nothing. */
 321         if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
 322                 return;
 323
 324         if (maniptype == NF_NAT_MANIP_SRC)
 325                 var_ipp = &tuple->src.u3;
 326         else
 327                 var_ipp = &tuple->dst.u3;
 328
 329         /* Fast path: only one choice. */
 330         if (nf_inet_addr_cmp(&range->min_addr, &range->max_addr)) {
 331                 *var_ipp = range->min_addr;
 332                 return;
 333         }
 334
 335         if (nf_ct_l3num(ct) == NFPROTO_IPV4)
 336                 max = sizeof(var_ipp->ip) / sizeof(u32) - 1;
 337         else
 338                 max = sizeof(var_ipp->ip6) / sizeof(u32) - 1;
 339
 340         /* Hashing source and destination IPs gives a fairly even
 341          * spread in practice (if there are a small number of IPs
 342          * involved, there usually aren't that many connections
 343          * anyway).  The consistency means that servers see the same
 344          * client coming from the same IP (some Internet Banking sites
 345          * like this), even across reboots.
 346          */
 347         j = jhash2((u32 *)&tuple->src.u3, sizeof(tuple->src.u3) / sizeof(u32),
 348                    range->flags & NF_NAT_RANGE_PERSISTENT ?
 349                         0 : (__force u32)tuple->dst.u3.all[max] ^ zone->id);
 350
 351         full_range = false;
 352         for (i = 0; i <= max; i++) {
 353                 /* If first bytes of the address are at the maximum, use the
 354                  * distance. Otherwise use the full range.
 355                  */
 356                 if (!full_range) {
 357                         minip = ntohl((__force __be32)range->min_addr.all[i]);
 358                         maxip = ntohl((__force __be32)range->max_addr.all[i]);
 359                         dist  = maxip - minip + 1;
 360                 } else {
 361                         minip = 0;
 362                         dist  = ~0;
 363                 }
 364
 365                 var_ipp->all[i] = (__force __u32)
 366                         htonl(minip + reciprocal_scale(j, dist));
 367                 if (var_ipp->all[i] != range->max_addr.all[i])
 368                         full_range = true;
 369
 370                 if (!(range->flags & NF_NAT_RANGE_PERSISTENT))
 371                         j ^= (__force u32)tuple->dst.u3.all[i];
 372         }
 373 }
 374
 375 /* Alter the per-proto part of the tuple (depending on maniptype), to
 376  * give a unique tuple in the given range if possible.
 377  *
 378  * Per-protocol part of tuple is initialized to the incoming packet.
 379  */
 380 static void nf_nat_l4proto_unique_tuple(struct nf_conntrack_tuple *tuple,
 381                                         const struct nf_nat_range2 *range,
 382                                         enum nf_nat_manip_type maniptype,
 383                                         const struct nf_conn *ct)
 384 {
 385         unsigned int range_size, min, max, i, attempts;
 386         __be16 *keyptr;
 387         u16 off;
 388         static const unsigned int max_attempts = 128;
 389
 390         switch (tuple->dst.protonum) {
 391         case IPPROTO_ICMP:
 392         case IPPROTO_ICMPV6:
 393                 /* id is same for either direction... */
 394                 keyptr = &tuple->src.u.icmp.id;
 395                 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
 396                         min = 0;
 397                         range_size = 65536;
 398                 } else {
 399                         min = ntohs(range->min_proto.icmp.id);
 400                         range_size = ntohs(range->max_proto.icmp.id) -
 401                                      ntohs(range->min_proto.icmp.id) + 1;
 402                 }
 403                 goto find_free_id;
 404 #if IS_ENABLED(CONFIG_NF_CT_PROTO_GRE)
 405         case IPPROTO_GRE:
 406                 /* If there is no master conntrack we are not PPTP,
 407                    do not change tuples */
 408                 if (!ct->master)
 409                         return;
 410
 411                 if (maniptype == NF_NAT_MANIP_SRC)
 412                         keyptr = &tuple->src.u.gre.key;
 413                 else
 414                         keyptr = &tuple->dst.u.gre.key;
 415
 416                 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
 417                         min = 1;
 418                         range_size = 65535;
 419                 } else {
 420                         min = ntohs(range->min_proto.gre.key);
 421                         range_size = ntohs(range->max_proto.gre.key) - min + 1;
 422                 }
 423                 goto find_free_id;
 424 #endif
 425         case IPPROTO_UDP:
 426         case IPPROTO_UDPLITE:
 427         case IPPROTO_TCP:
 428         case IPPROTO_SCTP:
 429         case IPPROTO_DCCP:
 430                 if (maniptype == NF_NAT_MANIP_SRC)
 431                         keyptr = &tuple->src.u.all;
 432                 else
 433                         keyptr = &tuple->dst.u.all;
 434
 435                 break;
 436         default:
 437                 return;
 438         }
 439
 440         /* If no range specified... */
 441         if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
 442                 /* If it's dst rewrite, can't change port */
 443                 if (maniptype == NF_NAT_MANIP_DST)
 444                         return;
 445
 446                 if (ntohs(*keyptr) < 1024) {
 447                         /* Loose convention: >> 512 is credential passing */
 448                         if (ntohs(*keyptr) < 512) {
 449                                 min = 1;
 450                                 range_size = 511 - min + 1;
 451                         } else {
 452                                 min = 600;
 453                                 range_size = 1023 - min + 1;
 454                         }
 455                 } else {
 456                         min = 1024;
 457                         range_size = 65535 - 1024 + 1;
 458                 }
 459         } else {
 460                 min = ntohs(range->min_proto.all);
 461                 max = ntohs(range->max_proto.all);
 462                 if (unlikely(max < min))
 463                         swap(max, min);
 464                 range_size = max - min + 1;
 465         }
 466
 467 find_free_id:
 468         if (range->flags & NF_NAT_RANGE_PROTO_OFFSET)
 469                 off = (ntohs(*keyptr) - ntohs(range->base_proto.all));
 470         else
 471                 off = prandom_u32();
 472
 473         attempts = range_size;
 474         if (attempts > max_attempts)
 475                 attempts = max_attempts;
 476
 477         /* We are in softirq; doing a search of the entire range risks
 478          * soft lockup when all tuples are already used.
 479          *
 480          * If we can't find any free port from first offset, pick a new
 481          * one and try again, with ever smaller search window.
 482          */
 483 another_round:
 484         for (i = 0; i < attempts; i++, off++) {
 485                 *keyptr = htons(min + off % range_size);
 486                 if (!nf_nat_used_tuple(tuple, ct))
 487                         return;
 488         }
 489
 490         if (attempts >= range_size || attempts < 16)
 491                 return;
 492         attempts /= 2;
 493         off = prandom_u32();
 494         goto another_round;
 495 }
 496
 497 /* Manipulate the tuple into the range given. For NF_INET_POST_ROUTING,
 498  * we change the source to map into the range. For NF_INET_PRE_ROUTING
 499  * and NF_INET_LOCAL_OUT, we change the destination to map into the
 500  * range. It might not be possible to get a unique tuple, but we try.
 501  * At worst (or if we race), we will end up with a final duplicate in
 502  * __nf_conntrack_confirm and drop the packet. */
 503 static void
 504 get_unique_tuple(struct nf_conntrack_tuple *tuple,
 505                  const struct nf_conntrack_tuple *orig_tuple,
 506                  const struct nf_nat_range2 *range,
 507                  struct nf_conn *ct,
 508                  enum nf_nat_manip_type maniptype)
 509 {
 510         const struct nf_conntrack_zone *zone;
 511         struct net *net = nf_ct_net(ct);
 512
 513         zone = nf_ct_zone(ct);
 514
 515         /* 1) If this srcip/proto/src-proto-part is currently mapped,
 516          * and that same mapping gives a unique tuple within the given
 517          * range, use that.
 518          *
 519          * This is only required for source (ie. NAT/masq) mappings.
 520          * So far, we don't do local source mappings, so multiple
 521          * manips not an issue.
 522          */
 523         if (maniptype == NF_NAT_MANIP_SRC &&
 524             !(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
 525                 /* try the original tuple first */
 526                 if (in_range(orig_tuple, range)) {
 527                         if (!nf_nat_used_tuple(orig_tuple, ct)) {
 528                                 *tuple = *orig_tuple;
 529                                 return;
 530                         }
 531                 } else if (find_appropriate_src(net, zone,
 532                                                 orig_tuple, tuple, range)) {
 533                         pr_debug("get_unique_tuple: Found current src map\n");
 534                         if (!nf_nat_used_tuple(tuple, ct))
 535                                 return;
 536                 }
 537         }
 538
 539         /* 2) Select the least-used IP/proto combination in the given range */
 540         *tuple = *orig_tuple;
 541         find_best_ips_proto(zone, tuple, range, ct, maniptype);
 542
 543         /* 3) The per-protocol part of the manip is made to map into
 544          * the range to make a unique tuple.
 545          */
 546
 547         /* Only bother mapping if it's not already in range and unique */
 548         if (!(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
 549                 if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
 550                         if (!(range->flags & NF_NAT_RANGE_PROTO_OFFSET) &&
 551                             l4proto_in_range(tuple, maniptype,
 552                                   &range->min_proto,
 553                                   &range->max_proto) &&
 554                             (range->min_proto.all == range->max_proto.all ||
 555                              !nf_nat_used_tuple(tuple, ct)))
 556                                 return;
 557                 } else if (!nf_nat_used_tuple(tuple, ct)) {
 558                         return;
 559                 }
 560         }
 561
 562         /* Last chance: get protocol to try to obtain unique tuple. */
 563         nf_nat_l4proto_unique_tuple(tuple, range, maniptype, ct);
 564 }
 565
 566 struct nf_conn_nat *nf_ct_nat_ext_add(struct nf_conn *ct)
 567 {
 568         struct nf_conn_nat *nat = nfct_nat(ct);
 569         if (nat)
 570                 return nat;
 571
 572         if (!nf_ct_is_confirmed(ct))
 573                 nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
 574
 575         return nat;
 576 }
 577 EXPORT_SYMBOL_GPL(nf_ct_nat_ext_add);
 578
 579 unsigned int
 580 nf_nat_setup_info(struct nf_conn *ct,
 581                   const struct nf_nat_range2 *range,
 582                   enum nf_nat_manip_type maniptype)
 583 {
 584         struct net *net = nf_ct_net(ct);
 585         struct nf_conntrack_tuple curr_tuple, new_tuple;
 586
 587         /* Can't setup nat info for confirmed ct. */
 588         if (nf_ct_is_confirmed(ct))
 589                 return NF_ACCEPT;
 590
 591         WARN_ON(maniptype != NF_NAT_MANIP_SRC &&
 592                 maniptype != NF_NAT_MANIP_DST);
 593
 594         if (WARN_ON(nf_nat_initialized(ct, maniptype)))
 595                 return NF_DROP;
 596
 597         /* What we've got will look like inverse of reply. Normally
 598          * this is what is in the conntrack, except for prior
 599          * manipulations (future optimization: if num_manips == 0,
 600          * orig_tp = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple)
 601          */
 602         nf_ct_invert_tuple(&curr_tuple,
 603                            &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
 604
 605         get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype);
 606
 607         if (!nf_ct_tuple_equal(&new_tuple, &curr_tuple)) {
 608                 struct nf_conntrack_tuple reply;
 609
 610                 /* Alter conntrack table so will recognize replies. */
 611                 nf_ct_invert_tuple(&reply, &new_tuple);
 612                 nf_conntrack_alter_reply(ct, &reply);
 613
 614                 /* Non-atomic: we own this at the moment. */
 615                 if (maniptype == NF_NAT_MANIP_SRC)
 616                         ct->status |= IPS_SRC_NAT;
 617                 else
 618                         ct->status |= IPS_DST_NAT;
 619
 620                 if (nfct_help(ct) && !nfct_seqadj(ct))
 621                         if (!nfct_seqadj_ext_add(ct))
 622                                 return NF_DROP;
 623         }
 624
 625         if (maniptype == NF_NAT_MANIP_SRC) {
 626                 unsigned int srchash;
 627                 spinlock_t *lock;
 628
 629                 srchash = hash_by_src(net, nf_ct_zone(ct),
 630                                       &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
 631                 lock = &nf_nat_locks[srchash % CONNTRACK_LOCKS];
 632                 spin_lock_bh(lock);
 633                 hlist_add_head_rcu(&ct->nat_bysource,
 634                                    &nf_nat_bysource[srchash]);
 635                 spin_unlock_bh(lock);
 636         }
 637
 638         /* It's done. */
 639         if (maniptype == NF_NAT_MANIP_DST)
 640                 ct->status |= IPS_DST_NAT_DONE;
 641         else
 642                 ct->status |= IPS_SRC_NAT_DONE;
 643
 644         return NF_ACCEPT;
 645 }
 646 EXPORT_SYMBOL(nf_nat_setup_info);
 647
 648 static unsigned int
 649 __nf_nat_alloc_null_binding(struct nf_conn *ct, enum nf_nat_manip_type manip)
 650 {
 651         /* Force range to this IP; let proto decide mapping for
 652          * per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
 653          * Use reply in case it's already been mangled (eg local packet).
 654          */
 655         union nf_inet_addr ip =
 656                 (manip == NF_NAT_MANIP_SRC ?
 657                 ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3 :
 658                 ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3);
 659         struct nf_nat_range2 range = {
 660                 .flags          = NF_NAT_RANGE_MAP_IPS,
 661                 .min_addr       = ip,
 662                 .max_addr       = ip,
 663         };
 664         return nf_nat_setup_info(ct, &range, manip);
 665 }
 666
 667 unsigned int
 668 nf_nat_alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
 669 {
 670         return __nf_nat_alloc_null_binding(ct, HOOK2MANIP(hooknum));
 671 }
 672 EXPORT_SYMBOL_GPL(nf_nat_alloc_null_binding);
 673
 674 /* Do packet manipulations according to nf_nat_setup_info. */
 675 unsigned int nf_nat_packet(struct nf_conn *ct,
 676                            enum ip_conntrack_info ctinfo,
 677                            unsigned int hooknum,
 678                            struct sk_buff *skb)
 679 {
 680         enum nf_nat_manip_type mtype = HOOK2MANIP(hooknum);
 681         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 682         unsigned int verdict = NF_ACCEPT;
 683         unsigned long statusbit;
 684
 685         if (mtype == NF_NAT_MANIP_SRC)
 686                 statusbit = IPS_SRC_NAT;
 687         else
 688                 statusbit = IPS_DST_NAT;
 689
 690         /* Invert if this is reply dir. */
 691         if (dir == IP_CT_DIR_REPLY)
 692                 statusbit ^= IPS_NAT_MASK;
 693
 694         /* Non-atomic: these bits don't change. */
 695         if (ct->status & statusbit)
 696                 verdict = nf_nat_manip_pkt(skb, ct, mtype, dir);
 697
 698         return verdict;
 699 }
 700 EXPORT_SYMBOL_GPL(nf_nat_packet);
 701
 702 static bool in_vrf_postrouting(const struct nf_hook_state *state)
 703 {
 704 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
 705         if (state->hook == NF_INET_POST_ROUTING &&
 706             netif_is_l3_master(state->out))
 707                 return true;
 708 #endif
 709         return false;
 710 }
 711
 712 unsigned int
 713 nf_nat_inet_fn(void *priv, struct sk_buff *skb,
 714                const struct nf_hook_state *state)
 715 {
 716         struct nf_conn *ct;
 717         enum ip_conntrack_info ctinfo;
 718         struct nf_conn_nat *nat;
 719         /* maniptype == SRC for postrouting. */
 720         enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook);
 721
 722         ct = nf_ct_get(skb, &ctinfo);
 723         /* Can't track?  It's not due to stress, or conntrack would
 724          * have dropped it.  Hence it's the user's responsibilty to
 725          * packet filter it out, or implement conntrack/NAT for that
 726          * protocol. 8) --RR
 727          */
 728         if (!ct || in_vrf_postrouting(state))
 729                 return NF_ACCEPT;
 730
 731         nat = nfct_nat(ct);
 732
 733         switch (ctinfo) {
 734         case IP_CT_RELATED:
 735         case IP_CT_RELATED_REPLY:
 736                 /* Only ICMPs can be IP_CT_IS_REPLY.  Fallthrough */
 737         case IP_CT_NEW:
 738                 /* Seen it before?  This can happen for loopback, retrans,
 739                  * or local packets.
 740                  */
 741                 if (!nf_nat_initialized(ct, maniptype)) {
 742                         struct nf_nat_lookup_hook_priv *lpriv = priv;
 743                         struct nf_hook_entries *e = rcu_dereference(lpriv->entries);
 744                         unsigned int ret;
 745                         int i;
 746
 747                         if (!e)
 748                                 goto null_bind;
 749
 750                         for (i = 0; i < e->num_hook_entries; i++) {
 751                                 ret = e->hooks[i].hook(e->hooks[i].priv, skb,
 752                                                        state);
 753                                 if (ret != NF_ACCEPT)
 754                                         return ret;
 755                                 if (nf_nat_initialized(ct, maniptype))
 756                                         goto do_nat;
 757                         }
 758 null_bind:
 759                         ret = nf_nat_alloc_null_binding(ct, state->hook);
 760                         if (ret != NF_ACCEPT)
 761                                 return ret;
 762                 } else {
 763                         pr_debug("Already setup manip %s for ct %p (status bits 0x%lx)\n",
 764                                  maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
 765                                  ct, ct->status);
 766                         if (nf_nat_oif_changed(state->hook, ctinfo, nat,
 767                                                state->out))
 768                                 goto oif_changed;
 769                 }
 770                 break;
 771         default:
 772                 /* ESTABLISHED */
 773                 WARN_ON(ctinfo != IP_CT_ESTABLISHED &&
 774                         ctinfo != IP_CT_ESTABLISHED_REPLY);
 775                 if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
 776                         goto oif_changed;
 777         }
 778 do_nat:
 779         return nf_nat_packet(ct, ctinfo, state->hook, skb);
 780
 781 oif_changed:
 782         nf_ct_kill_acct(ct, ctinfo, skb);
 783         return NF_DROP;
 784 }
 785 EXPORT_SYMBOL_GPL(nf_nat_inet_fn);
 786
 787 struct nf_nat_proto_clean {
 788         u8      l3proto;
 789         u8      l4proto;
 790 };
 791
 792 /* kill conntracks with affected NAT section */
 793 static int nf_nat_proto_remove(struct nf_conn *i, void *data)
 794 {
 795         const struct nf_nat_proto_clean *clean = data;
 796
 797         if ((clean->l3proto && nf_ct_l3num(i) != clean->l3proto) ||
 798             (clean->l4proto && nf_ct_protonum(i) != clean->l4proto))
 799                 return 0;
 800
 801         return i->status & IPS_NAT_MASK ? 1 : 0;
 802 }
 803
 804 static void nf_nat_cleanup_conntrack(struct nf_conn *ct)
 805 {
 806         unsigned int h;
 807
 808         h = hash_by_src(nf_ct_net(ct), nf_ct_zone(ct), &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
 809         spin_lock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]);
 810         hlist_del_rcu(&ct->nat_bysource);
 811         spin_unlock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]);
 812 }
 813
 814 static int nf_nat_proto_clean(struct nf_conn *ct, void *data)
 815 {
 816         if (nf_nat_proto_remove(ct, data))
 817                 return 1;
 818
 819         /* This module is being removed and conntrack has nat null binding.
 820          * Remove it from bysource hash, as the table will be freed soon.
 821          *
 822          * Else, when the conntrack is destoyed, nf_nat_cleanup_conntrack()
 823          * will delete entry from already-freed table.
 824          */
 825         if (test_and_clear_bit(IPS_SRC_NAT_DONE_BIT, &ct->status))
 826                 nf_nat_cleanup_conntrack(ct);
 827
 828         /* don't delete conntrack.  Although that would make things a lot
 829          * simpler, we'd end up flushing all conntracks on nat rmmod.
 830          */
 831         return 0;
 832 }
 833
 834 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 835
 836 #include <linux/netfilter/nfnetlink.h>
 837 #include <linux/netfilter/nfnetlink_conntrack.h>
 838
 839 static const struct nla_policy protonat_nla_policy[CTA_PROTONAT_MAX+1] = {
 840         [CTA_PROTONAT_PORT_MIN] = { .type = NLA_U16 },
 841         [CTA_PROTONAT_PORT_MAX] = { .type = NLA_U16 },
 842 };
 843
 844 static int nf_nat_l4proto_nlattr_to_range(struct nlattr *tb[],
 845                                           struct nf_nat_range2 *range)
 846 {
 847         if (tb[CTA_PROTONAT_PORT_MIN]) {
 848                 range->min_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MIN]);
 849                 range->max_proto.all = range->min_proto.all;
 850                 range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
 851         }
 852         if (tb[CTA_PROTONAT_PORT_MAX]) {
 853                 range->max_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MAX]);
 854                 range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
 855         }
 856         return 0;
 857 }
 858
 859 static int nfnetlink_parse_nat_proto(struct nlattr *attr,
 860                                      const struct nf_conn *ct,
 861                                      struct nf_nat_range2 *range)
 862 {
 863         struct nlattr *tb[CTA_PROTONAT_MAX+1];
 864         int err;
 865
 866         err = nla_parse_nested_deprecated(tb, CTA_PROTONAT_MAX, attr,
 867                                           protonat_nla_policy, NULL);
 868         if (err < 0)
 869                 return err;
 870
 871         return nf_nat_l4proto_nlattr_to_range(tb, range);
 872 }
 873
 874 static const struct nla_policy nat_nla_policy[CTA_NAT_MAX+1] = {
 875         [CTA_NAT_V4_MINIP]      = { .type = NLA_U32 },
 876         [CTA_NAT_V4_MAXIP]      = { .type = NLA_U32 },
 877         [CTA_NAT_V6_MINIP]      = { .len = sizeof(struct in6_addr) },
 878         [CTA_NAT_V6_MAXIP]      = { .len = sizeof(struct in6_addr) },
 879         [CTA_NAT_PROTO]         = { .type = NLA_NESTED },
 880 };
 881
 882 static int nf_nat_ipv4_nlattr_to_range(struct nlattr *tb[],
 883                                        struct nf_nat_range2 *range)
 884 {
 885         if (tb[CTA_NAT_V4_MINIP]) {
 886                 range->min_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MINIP]);
 887                 range->flags |= NF_NAT_RANGE_MAP_IPS;
 888         }
 889
 890         if (tb[CTA_NAT_V4_MAXIP])
 891                 range->max_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MAXIP]);
 892         else
 893                 range->max_addr.ip = range->min_addr.ip;
 894
 895         return 0;
 896 }
 897
 898 static int nf_nat_ipv6_nlattr_to_range(struct nlattr *tb[],
 899                                        struct nf_nat_range2 *range)
 900 {
 901         if (tb[CTA_NAT_V6_MINIP]) {
 902                 nla_memcpy(&range->min_addr.ip6, tb[CTA_NAT_V6_MINIP],
 903                            sizeof(struct in6_addr));
 904                 range->flags |= NF_NAT_RANGE_MAP_IPS;
 905         }
 906
 907         if (tb[CTA_NAT_V6_MAXIP])
 908                 nla_memcpy(&range->max_addr.ip6, tb[CTA_NAT_V6_MAXIP],
 909                            sizeof(struct in6_addr));
 910         else
 911                 range->max_addr = range->min_addr;
 912
 913         return 0;
 914 }
 915
 916 static int
 917 nfnetlink_parse_nat(const struct nlattr *nat,
 918                     const struct nf_conn *ct, struct nf_nat_range2 *range)
 919 {
 920         struct nlattr *tb[CTA_NAT_MAX+1];
 921         int err;
 922
 923         memset(range, 0, sizeof(*range));
 924
 925         err = nla_parse_nested_deprecated(tb, CTA_NAT_MAX, nat,
 926                                           nat_nla_policy, NULL);
 927         if (err < 0)
 928                 return err;
 929
 930         switch (nf_ct_l3num(ct)) {
 931         case NFPROTO_IPV4:
 932                 err = nf_nat_ipv4_nlattr_to_range(tb, range);
 933                 break;
 934         case NFPROTO_IPV6:
 935                 err = nf_nat_ipv6_nlattr_to_range(tb, range);
 936                 break;
 937         default:
 938                 err = -EPROTONOSUPPORT;
 939                 break;
 940         }
 941
 942         if (err)
 943                 return err;
 944
 945         if (!tb[CTA_NAT_PROTO])
 946                 return 0;
 947
 948         return nfnetlink_parse_nat_proto(tb[CTA_NAT_PROTO], ct, range);
 949 }
 950
 951 /* This function is called under rcu_read_lock() */
 952 static int
 953 nfnetlink_parse_nat_setup(struct nf_conn *ct,
 954                           enum nf_nat_manip_type manip,
 955                           const struct nlattr *attr)
 956 {
 957         struct nf_nat_range2 range;
 958         int err;
 959
 960         /* Should not happen, restricted to creating new conntracks
 961          * via ctnetlink.
 962          */
 963         if (WARN_ON_ONCE(nf_nat_initialized(ct, manip)))
 964                 return -EEXIST;
 965
 966         /* No NAT information has been passed, allocate the null-binding */
 967         if (attr == NULL)
 968                 return __nf_nat_alloc_null_binding(ct, manip) == NF_DROP ? -ENOMEM : 0;
 969
 970         err = nfnetlink_parse_nat(attr, ct, &range);
 971         if (err < 0)
 972                 return err;
 973
 974         return nf_nat_setup_info(ct, &range, manip) == NF_DROP ? -ENOMEM : 0;
 975 }
 976 #else
 977 static int
 978 nfnetlink_parse_nat_setup(struct nf_conn *ct,
 979                           enum nf_nat_manip_type manip,
 980                           const struct nlattr *attr)
 981 {
 982         return -EOPNOTSUPP;
 983 }
 984 #endif
 985
 986 static struct nf_ct_helper_expectfn follow_master_nat = {
 987         .name           = "nat-follow-master",
 988         .expectfn       = nf_nat_follow_master,
 989 };
 990
 991 int nf_nat_register_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
 992                        const struct nf_hook_ops *orig_nat_ops, unsigned int ops_count)
 993 {
 994         struct nat_net *nat_net = net_generic(net, nat_net_id);
 995         struct nf_nat_hooks_net *nat_proto_net;
 996         struct nf_nat_lookup_hook_priv *priv;
 997         unsigned int hooknum = ops->hooknum;
 998         struct nf_hook_ops *nat_ops;
 999         int i, ret;
1000
1001         if (WARN_ON_ONCE(pf >= ARRAY_SIZE(nat_net->nat_proto_net)))
1002                 return -EINVAL;
1003
1004         nat_proto_net = &nat_net->nat_proto_net[pf];
1005
1006         for (i = 0; i < ops_count; i++) {
1007                 if (orig_nat_ops[i].hooknum == hooknum) {
1008                         hooknum = i;
1009                         break;
1010                 }
1011         }
1012
1013         if (WARN_ON_ONCE(i == ops_count))
1014                 return -EINVAL;
1015
1016         mutex_lock(&nf_nat_proto_mutex);
1017         if (!nat_proto_net->nat_hook_ops) {
1018                 WARN_ON(nat_proto_net->users != 0);
1019
1020                 nat_ops = kmemdup(orig_nat_ops, sizeof(*orig_nat_ops) * ops_count, GFP_KERNEL);
1021                 if (!nat_ops) {
1022                         mutex_unlock(&nf_nat_proto_mutex);
1023                         return -ENOMEM;
1024                 }
1025
1026                 for (i = 0; i < ops_count; i++) {
1027                         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
1028                         if (priv) {
1029                                 nat_ops[i].priv = priv;
1030                                 continue;
1031                         }
1032                         mutex_unlock(&nf_nat_proto_mutex);
1033                         while (i)
1034                                 kfree(nat_ops[--i].priv);
1035                         kfree(nat_ops);
1036                         return -ENOMEM;
1037                 }
1038
1039                 ret = nf_register_net_hooks(net, nat_ops, ops_count);
1040                 if (ret < 0) {
1041                         mutex_unlock(&nf_nat_proto_mutex);
1042                         for (i = 0; i < ops_count; i++)
1043                                 kfree(nat_ops[i].priv);
1044                         kfree(nat_ops);
1045                         return ret;
1046                 }
1047
1048                 nat_proto_net->nat_hook_ops = nat_ops;
1049         }
1050
1051         nat_ops = nat_proto_net->nat_hook_ops;
1052         priv = nat_ops[hooknum].priv;
1053         if (WARN_ON_ONCE(!priv)) {
1054                 mutex_unlock(&nf_nat_proto_mutex);
1055                 return -EOPNOTSUPP;
1056         }
1057
1058         ret = nf_hook_entries_insert_raw(&priv->entries, ops);
1059         if (ret == 0)
1060                 nat_proto_net->users++;
1061
1062         mutex_unlock(&nf_nat_proto_mutex);
1063         return ret;
1064 }
1065
1066 void nf_nat_unregister_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
1067                           unsigned int ops_count)
1068 {
1069         struct nat_net *nat_net = net_generic(net, nat_net_id);
1070         struct nf_nat_hooks_net *nat_proto_net;
1071         struct nf_nat_lookup_hook_priv *priv;
1072         struct nf_hook_ops *nat_ops;
1073         int hooknum = ops->hooknum;
1074         int i;
1075
1076         if (pf >= ARRAY_SIZE(nat_net->nat_proto_net))
1077                 return;
1078
1079         nat_proto_net = &nat_net->nat_proto_net[pf];
1080
1081         mutex_lock(&nf_nat_proto_mutex);
1082         if (WARN_ON(nat_proto_net->users == 0))
1083                 goto unlock;
1084
1085         nat_proto_net->users--;
1086
1087         nat_ops = nat_proto_net->nat_hook_ops;
1088         for (i = 0; i < ops_count; i++) {
1089                 if (nat_ops[i].hooknum == hooknum) {
1090                         hooknum = i;
1091                         break;
1092                 }
1093         }
1094         if (WARN_ON_ONCE(i == ops_count))
1095                 goto unlock;
1096         priv = nat_ops[hooknum].priv;
1097         nf_hook_entries_delete_raw(&priv->entries, ops);
1098
1099         if (nat_proto_net->users == 0) {
1100                 nf_unregister_net_hooks(net, nat_ops, ops_count);
1101
1102                 for (i = 0; i < ops_count; i++) {
1103                         priv = nat_ops[i].priv;
1104                         kfree_rcu(priv, rcu_head);
1105                 }
1106
1107                 nat_proto_net->nat_hook_ops = NULL;
1108                 kfree(nat_ops);
1109         }
1110 unlock:
1111         mutex_unlock(&nf_nat_proto_mutex);
1112 }
1113
1114 static struct pernet_operations nat_net_ops = {
1115         .id = &nat_net_id,
1116         .size = sizeof(struct nat_net),
1117 };
1118
1119 static const struct nf_nat_hook nat_hook = {
1120         .parse_nat_setup        = nfnetlink_parse_nat_setup,
1121 #ifdef CONFIG_XFRM
1122         .decode_session         = __nf_nat_decode_session,
1123 #endif
1124         .manip_pkt              = nf_nat_manip_pkt,
1125         .remove_nat_bysrc       = nf_nat_cleanup_conntrack,
1126 };
1127
1128 static int __init nf_nat_init(void)
1129 {
1130         int ret, i;
1131
1132         /* Leave them the same for the moment. */
1133         nf_nat_htable_size = nf_conntrack_htable_size;
1134         if (nf_nat_htable_size < CONNTRACK_LOCKS)
1135                 nf_nat_htable_size = CONNTRACK_LOCKS;
1136
1137         nf_nat_bysource = nf_ct_alloc_hashtable(&nf_nat_htable_size, 0);
1138         if (!nf_nat_bysource)
1139                 return -ENOMEM;
1140
1141         for (i = 0; i < CONNTRACK_LOCKS; i++)
1142                 spin_lock_init(&nf_nat_locks[i]);
1143
1144         ret = register_pernet_subsys(&nat_net_ops);
1145         if (ret < 0) {
1146                 kvfree(nf_nat_bysource);
1147                 return ret;
1148         }
1149
1150         nf_ct_helper_expectfn_register(&follow_master_nat);
1151
1152         WARN_ON(nf_nat_hook != NULL);
1153         RCU_INIT_POINTER(nf_nat_hook, &nat_hook);
1154
1155         return 0;
1156 }
1157
1158 static void __exit nf_nat_cleanup(void)
1159 {
1160         struct nf_nat_proto_clean clean = {};
1161
1162         nf_ct_iterate_destroy(nf_nat_proto_clean, &clean);
1163
1164         nf_ct_helper_expectfn_unregister(&follow_master_nat);
1165         RCU_INIT_POINTER(nf_nat_hook, NULL);
1166
1167         synchronize_net();
1168         kvfree(nf_nat_bysource);
1169         unregister_pernet_subsys(&nat_net_ops);
1170 }
1171
1172 MODULE_LICENSE("GPL");
1173
1174 module_init(nf_nat_init);
1175 module_exit(nf_nat_cleanup);