net/netfilter/nf_flow_table_core.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/kernel.h>
   3 #include <linux/init.h>
   4 #include <linux/module.h>
   5 #include <linux/netfilter.h>
   6 #include <linux/rhashtable.h>
   7 #include <linux/netdevice.h>
   8 #include <net/ip.h>
   9 #include <net/ip6_route.h>
  10 #include <net/netfilter/nf_tables.h>
  11 #include <net/netfilter/nf_flow_table.h>
  12 #include <net/netfilter/nf_conntrack.h>
  13 #include <net/netfilter/nf_conntrack_core.h>
  14 #include <net/netfilter/nf_conntrack_l4proto.h>
  15 #include <net/netfilter/nf_conntrack_tuple.h>
  16
  17 static DEFINE_MUTEX(flowtable_lock);
  18 static LIST_HEAD(flowtables);
  19
  20 static void
  21 flow_offload_fill_dir(struct flow_offload *flow,
  22                       enum flow_offload_tuple_dir dir)
  23 {
  24         struct flow_offload_tuple *ft = &flow->tuplehash[dir].tuple;
  25         struct nf_conntrack_tuple *ctt = &flow->ct->tuplehash[dir].tuple;
  26
  27         ft->dir = dir;
  28
  29         switch (ctt->src.l3num) {
  30         case NFPROTO_IPV4:
  31                 ft->src_v4 = ctt->src.u3.in;
  32                 ft->dst_v4 = ctt->dst.u3.in;
  33                 break;
  34         case NFPROTO_IPV6:
  35                 ft->src_v6 = ctt->src.u3.in6;
  36                 ft->dst_v6 = ctt->dst.u3.in6;
  37                 break;
  38         }
  39
  40         ft->l3proto = ctt->src.l3num;
  41         ft->l4proto = ctt->dst.protonum;
  42         ft->src_port = ctt->src.u.tcp.port;
  43         ft->dst_port = ctt->dst.u.tcp.port;
  44 }
  45
  46 struct flow_offload *flow_offload_alloc(struct nf_conn *ct)
  47 {
  48         struct flow_offload *flow;
  49
  50         if (unlikely(nf_ct_is_dying(ct) ||
  51             !atomic_inc_not_zero(&ct->ct_general.use)))
  52                 return NULL;
  53
  54         flow = kzalloc(sizeof(*flow), GFP_ATOMIC);
  55         if (!flow)
  56                 goto err_ct_refcnt;
  57
  58         flow->ct = ct;
  59
  60         flow_offload_fill_dir(flow, FLOW_OFFLOAD_DIR_ORIGINAL);
  61         flow_offload_fill_dir(flow, FLOW_OFFLOAD_DIR_REPLY);
  62
  63         if (ct->status & IPS_SRC_NAT)
  64                 __set_bit(NF_FLOW_SNAT, &flow->flags);
  65         if (ct->status & IPS_DST_NAT)
  66                 __set_bit(NF_FLOW_DNAT, &flow->flags);
  67
  68         return flow;
  69
  70 err_ct_refcnt:
  71         nf_ct_put(ct);
  72
  73         return NULL;
  74 }
  75 EXPORT_SYMBOL_GPL(flow_offload_alloc);
  76
  77 static int flow_offload_fill_route(struct flow_offload *flow,
  78                                    const struct nf_flow_route *route,
  79                                    enum flow_offload_tuple_dir dir)
  80 {
  81         struct flow_offload_tuple *flow_tuple = &flow->tuplehash[dir].tuple;
  82         struct dst_entry *dst = route->tuple[dir].dst;
  83         int i, j = 0;
  84
  85         switch (flow_tuple->l3proto) {
  86         case NFPROTO_IPV4:
  87                 flow_tuple->mtu = ip_dst_mtu_maybe_forward(dst, true);
  88                 break;
  89         case NFPROTO_IPV6:
  90                 flow_tuple->mtu = ip6_dst_mtu_forward(dst);
  91                 break;
  92         }
  93
  94         flow_tuple->iifidx = route->tuple[dir].in.ifindex;
  95         for (i = route->tuple[dir].in.num_encaps - 1; i >= 0; i--) {
  96                 flow_tuple->encap[j].id = route->tuple[dir].in.encap[i].id;
  97                 flow_tuple->encap[j].proto = route->tuple[dir].in.encap[i].proto;
  98                 j++;
  99         }
 100         flow_tuple->encap_num = route->tuple[dir].in.num_encaps;
 101
 102         switch (route->tuple[dir].xmit_type) {
 103         case FLOW_OFFLOAD_XMIT_DIRECT:
 104                 memcpy(flow_tuple->out.h_dest, route->tuple[dir].out.h_dest,
 105                        ETH_ALEN);
 106                 memcpy(flow_tuple->out.h_source, route->tuple[dir].out.h_source,
 107                        ETH_ALEN);
 108                 flow_tuple->out.ifidx = route->tuple[dir].out.ifindex;
 109                 break;
 110         case FLOW_OFFLOAD_XMIT_XFRM:
 111         case FLOW_OFFLOAD_XMIT_NEIGH:
 112                 if (!dst_hold_safe(route->tuple[dir].dst))
 113                         return -1;
 114
 115                 flow_tuple->dst_cache = dst;
 116                 break;
 117         }
 118         flow_tuple->xmit_type = route->tuple[dir].xmit_type;
 119
 120         return 0;
 121 }
 122
 123 static void nft_flow_dst_release(struct flow_offload *flow,
 124                                  enum flow_offload_tuple_dir dir)
 125 {
 126         if (flow->tuplehash[dir].tuple.xmit_type == FLOW_OFFLOAD_XMIT_NEIGH ||
 127             flow->tuplehash[dir].tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)
 128                 dst_release(flow->tuplehash[dir].tuple.dst_cache);
 129 }
 130
 131 int flow_offload_route_init(struct flow_offload *flow,
 132                             const struct nf_flow_route *route)
 133 {
 134         int err;
 135
 136         err = flow_offload_fill_route(flow, route, FLOW_OFFLOAD_DIR_ORIGINAL);
 137         if (err < 0)
 138                 return err;
 139
 140         err = flow_offload_fill_route(flow, route, FLOW_OFFLOAD_DIR_REPLY);
 141         if (err < 0)
 142                 goto err_route_reply;
 143
 144         flow->type = NF_FLOW_OFFLOAD_ROUTE;
 145
 146         return 0;
 147
 148 err_route_reply:
 149         nft_flow_dst_release(flow, FLOW_OFFLOAD_DIR_ORIGINAL);
 150
 151         return err;
 152 }
 153 EXPORT_SYMBOL_GPL(flow_offload_route_init);
 154
 155 static void flow_offload_fixup_tcp(struct ip_ct_tcp *tcp)
 156 {
 157         tcp->state = TCP_CONNTRACK_ESTABLISHED;
 158         tcp->seen[0].td_maxwin = 0;
 159         tcp->seen[1].td_maxwin = 0;
 160 }
 161
 162 #define NF_FLOWTABLE_TCP_PICKUP_TIMEOUT (120 * HZ)
 163 #define NF_FLOWTABLE_UDP_PICKUP_TIMEOUT (30 * HZ)
 164
 165 static void flow_offload_fixup_ct_timeout(struct nf_conn *ct)
 166 {
 167         const struct nf_conntrack_l4proto *l4proto;
 168         int l4num = nf_ct_protonum(ct);
 169         unsigned int timeout;
 170
 171         l4proto = nf_ct_l4proto_find(l4num);
 172         if (!l4proto)
 173                 return;
 174
 175         if (l4num == IPPROTO_TCP)
 176                 timeout = NF_FLOWTABLE_TCP_PICKUP_TIMEOUT;
 177         else if (l4num == IPPROTO_UDP)
 178                 timeout = NF_FLOWTABLE_UDP_PICKUP_TIMEOUT;
 179         else
 180                 return;
 181
 182         if (nf_flow_timeout_delta(ct->timeout) > (__s32)timeout)
 183                 ct->timeout = nfct_time_stamp + timeout;
 184 }
 185
 186 static void flow_offload_fixup_ct_state(struct nf_conn *ct)
 187 {
 188         if (nf_ct_protonum(ct) == IPPROTO_TCP)
 189                 flow_offload_fixup_tcp(&ct->proto.tcp);
 190 }
 191
 192 static void flow_offload_fixup_ct(struct nf_conn *ct)
 193 {
 194         flow_offload_fixup_ct_state(ct);
 195         flow_offload_fixup_ct_timeout(ct);
 196 }
 197
 198 static void flow_offload_route_release(struct flow_offload *flow)
 199 {
 200         nft_flow_dst_release(flow, FLOW_OFFLOAD_DIR_ORIGINAL);
 201         nft_flow_dst_release(flow, FLOW_OFFLOAD_DIR_REPLY);
 202 }
 203
 204 void flow_offload_free(struct flow_offload *flow)
 205 {
 206         switch (flow->type) {
 207         case NF_FLOW_OFFLOAD_ROUTE:
 208                 flow_offload_route_release(flow);
 209                 break;
 210         default:
 211                 break;
 212         }
 213         nf_ct_put(flow->ct);
 214         kfree_rcu(flow, rcu_head);
 215 }
 216 EXPORT_SYMBOL_GPL(flow_offload_free);
 217
 218 static u32 flow_offload_hash(const void *data, u32 len, u32 seed)
 219 {
 220         const struct flow_offload_tuple *tuple = data;
 221
 222         return jhash(tuple, offsetof(struct flow_offload_tuple, __hash), seed);
 223 }
 224
 225 static u32 flow_offload_hash_obj(const void *data, u32 len, u32 seed)
 226 {
 227         const struct flow_offload_tuple_rhash *tuplehash = data;
 228
 229         return jhash(&tuplehash->tuple, offsetof(struct flow_offload_tuple, __hash), seed);
 230 }
 231
 232 static int flow_offload_hash_cmp(struct rhashtable_compare_arg *arg,
 233                                         const void *ptr)
 234 {
 235         const struct flow_offload_tuple *tuple = arg->key;
 236         const struct flow_offload_tuple_rhash *x = ptr;
 237
 238         if (memcmp(&x->tuple, tuple, offsetof(struct flow_offload_tuple, __hash)))
 239                 return 1;
 240
 241         return 0;
 242 }
 243
 244 static const struct rhashtable_params nf_flow_offload_rhash_params = {
 245         .head_offset            = offsetof(struct flow_offload_tuple_rhash, node),
 246         .hashfn                 = flow_offload_hash,
 247         .obj_hashfn             = flow_offload_hash_obj,
 248         .obj_cmpfn              = flow_offload_hash_cmp,
 249         .automatic_shrinking    = true,
 250 };
 251
 252 int flow_offload_add(struct nf_flowtable *flow_table, struct flow_offload *flow)
 253 {
 254         int err;
 255
 256         flow->timeout = nf_flowtable_time_stamp + NF_FLOW_TIMEOUT;
 257
 258         err = rhashtable_insert_fast(&flow_table->rhashtable,
 259                                      &flow->tuplehash[0].node,
 260                                      nf_flow_offload_rhash_params);
 261         if (err < 0)
 262                 return err;
 263
 264         err = rhashtable_insert_fast(&flow_table->rhashtable,
 265                                      &flow->tuplehash[1].node,
 266                                      nf_flow_offload_rhash_params);
 267         if (err < 0) {
 268                 rhashtable_remove_fast(&flow_table->rhashtable,
 269                                        &flow->tuplehash[0].node,
 270                                        nf_flow_offload_rhash_params);
 271                 return err;
 272         }
 273
 274         nf_ct_offload_timeout(flow->ct);
 275
 276         if (nf_flowtable_hw_offload(flow_table)) {
 277                 __set_bit(NF_FLOW_HW, &flow->flags);
 278                 nf_flow_offload_add(flow_table, flow);
 279         }
 280
 281         return 0;
 282 }
 283 EXPORT_SYMBOL_GPL(flow_offload_add);
 284
 285 void flow_offload_refresh(struct nf_flowtable *flow_table,
 286                           struct flow_offload *flow)
 287 {
 288         flow->timeout = nf_flowtable_time_stamp + NF_FLOW_TIMEOUT;
 289
 290         if (likely(!nf_flowtable_hw_offload(flow_table) ||
 291                    !test_and_clear_bit(NF_FLOW_HW_REFRESH, &flow->flags)))
 292                 return;
 293
 294         nf_flow_offload_add(flow_table, flow);
 295 }
 296 EXPORT_SYMBOL_GPL(flow_offload_refresh);
 297
 298 static inline bool nf_flow_has_expired(const struct flow_offload *flow)
 299 {
 300         return nf_flow_timeout_delta(flow->timeout) <= 0;
 301 }
 302
 303 static void flow_offload_del(struct nf_flowtable *flow_table,
 304                              struct flow_offload *flow)
 305 {
 306         rhashtable_remove_fast(&flow_table->rhashtable,
 307                                &flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].node,
 308                                nf_flow_offload_rhash_params);
 309         rhashtable_remove_fast(&flow_table->rhashtable,
 310                                &flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].node,
 311                                nf_flow_offload_rhash_params);
 312
 313         clear_bit(IPS_OFFLOAD_BIT, &flow->ct->status);
 314
 315         if (nf_flow_has_expired(flow))
 316                 flow_offload_fixup_ct(flow->ct);
 317         else
 318                 flow_offload_fixup_ct_timeout(flow->ct);
 319
 320         flow_offload_free(flow);
 321 }
 322
 323 void flow_offload_teardown(struct flow_offload *flow)
 324 {
 325         set_bit(NF_FLOW_TEARDOWN, &flow->flags);
 326
 327         flow_offload_fixup_ct_state(flow->ct);
 328 }
 329 EXPORT_SYMBOL_GPL(flow_offload_teardown);
 330
 331 struct flow_offload_tuple_rhash *
 332 flow_offload_lookup(struct nf_flowtable *flow_table,
 333                     struct flow_offload_tuple *tuple)
 334 {
 335         struct flow_offload_tuple_rhash *tuplehash;
 336         struct flow_offload *flow;
 337         int dir;
 338
 339         tuplehash = rhashtable_lookup(&flow_table->rhashtable, tuple,
 340                                       nf_flow_offload_rhash_params);
 341         if (!tuplehash)
 342                 return NULL;
 343
 344         dir = tuplehash->tuple.dir;
 345         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 346         if (test_bit(NF_FLOW_TEARDOWN, &flow->flags))
 347                 return NULL;
 348
 349         if (unlikely(nf_ct_is_dying(flow->ct)))
 350                 return NULL;
 351
 352         return tuplehash;
 353 }
 354 EXPORT_SYMBOL_GPL(flow_offload_lookup);
 355
 356 static int
 357 nf_flow_table_iterate(struct nf_flowtable *flow_table,
 358                       void (*iter)(struct flow_offload *flow, void *data),
 359                       void *data)
 360 {
 361         struct flow_offload_tuple_rhash *tuplehash;
 362         struct rhashtable_iter hti;
 363         struct flow_offload *flow;
 364         int err = 0;
 365
 366         rhashtable_walk_enter(&flow_table->rhashtable, &hti);
 367         rhashtable_walk_start(&hti);
 368
 369         while ((tuplehash = rhashtable_walk_next(&hti))) {
 370                 if (IS_ERR(tuplehash)) {
 371                         if (PTR_ERR(tuplehash) != -EAGAIN) {
 372                                 err = PTR_ERR(tuplehash);
 373                                 break;
 374                         }
 375                         continue;
 376                 }
 377                 if (tuplehash->tuple.dir)
 378                         continue;
 379
 380                 flow = container_of(tuplehash, struct flow_offload, tuplehash[0]);
 381
 382                 iter(flow, data);
 383         }
 384         rhashtable_walk_stop(&hti);
 385         rhashtable_walk_exit(&hti);
 386
 387         return err;
 388 }
 389
 390 static void nf_flow_offload_gc_step(struct flow_offload *flow, void *data)
 391 {
 392         struct nf_flowtable *flow_table = data;
 393
 394         if (nf_flow_has_expired(flow) || nf_ct_is_dying(flow->ct))
 395                 set_bit(NF_FLOW_TEARDOWN, &flow->flags);
 396
 397         if (test_bit(NF_FLOW_TEARDOWN, &flow->flags)) {
 398                 if (test_bit(NF_FLOW_HW, &flow->flags)) {
 399                         if (!test_bit(NF_FLOW_HW_DYING, &flow->flags))
 400                                 nf_flow_offload_del(flow_table, flow);
 401                         else if (test_bit(NF_FLOW_HW_DEAD, &flow->flags))
 402                                 flow_offload_del(flow_table, flow);
 403                 } else {
 404                         flow_offload_del(flow_table, flow);
 405                 }
 406         } else if (test_bit(NF_FLOW_HW, &flow->flags)) {
 407                 nf_flow_offload_stats(flow_table, flow);
 408         }
 409 }
 410
 411 static void nf_flow_offload_work_gc(struct work_struct *work)
 412 {
 413         struct nf_flowtable *flow_table;
 414
 415         flow_table = container_of(work, struct nf_flowtable, gc_work.work);
 416         nf_flow_table_iterate(flow_table, nf_flow_offload_gc_step, flow_table);
 417         queue_delayed_work(system_power_efficient_wq, &flow_table->gc_work, HZ);
 418 }
 419
 420 static void nf_flow_nat_port_tcp(struct sk_buff *skb, unsigned int thoff,
 421                                  __be16 port, __be16 new_port)
 422 {
 423         struct tcphdr *tcph;
 424
 425         tcph = (void *)(skb_network_header(skb) + thoff);
 426         inet_proto_csum_replace2(&tcph->check, skb, port, new_port, false);
 427 }
 428
 429 static void nf_flow_nat_port_udp(struct sk_buff *skb, unsigned int thoff,
 430                                  __be16 port, __be16 new_port)
 431 {
 432         struct udphdr *udph;
 433
 434         udph = (void *)(skb_network_header(skb) + thoff);
 435         if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
 436                 inet_proto_csum_replace2(&udph->check, skb, port,
 437                                          new_port, false);
 438                 if (!udph->check)
 439                         udph->check = CSUM_MANGLED_0;
 440         }
 441 }
 442
 443 static void nf_flow_nat_port(struct sk_buff *skb, unsigned int thoff,
 444                              u8 protocol, __be16 port, __be16 new_port)
 445 {
 446         switch (protocol) {
 447         case IPPROTO_TCP:
 448                 nf_flow_nat_port_tcp(skb, thoff, port, new_port);
 449                 break;
 450         case IPPROTO_UDP:
 451                 nf_flow_nat_port_udp(skb, thoff, port, new_port);
 452                 break;
 453         }
 454 }
 455
 456 void nf_flow_snat_port(const struct flow_offload *flow,
 457                        struct sk_buff *skb, unsigned int thoff,
 458                        u8 protocol, enum flow_offload_tuple_dir dir)
 459 {
 460         struct flow_ports *hdr;
 461         __be16 port, new_port;
 462
 463         hdr = (void *)(skb_network_header(skb) + thoff);
 464
 465         switch (dir) {
 466         case FLOW_OFFLOAD_DIR_ORIGINAL:
 467                 port = hdr->source;
 468                 new_port = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_port;
 469                 hdr->source = new_port;
 470                 break;
 471         case FLOW_OFFLOAD_DIR_REPLY:
 472                 port = hdr->dest;
 473                 new_port = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_port;
 474                 hdr->dest = new_port;
 475                 break;
 476         }
 477
 478         nf_flow_nat_port(skb, thoff, protocol, port, new_port);
 479 }
 480 EXPORT_SYMBOL_GPL(nf_flow_snat_port);
 481
 482 void nf_flow_dnat_port(const struct flow_offload *flow, struct sk_buff *skb,
 483                        unsigned int thoff, u8 protocol,
 484                        enum flow_offload_tuple_dir dir)
 485 {
 486         struct flow_ports *hdr;
 487         __be16 port, new_port;
 488
 489         hdr = (void *)(skb_network_header(skb) + thoff);
 490
 491         switch (dir) {
 492         case FLOW_OFFLOAD_DIR_ORIGINAL:
 493                 port = hdr->dest;
 494                 new_port = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_port;
 495                 hdr->dest = new_port;
 496                 break;
 497         case FLOW_OFFLOAD_DIR_REPLY:
 498                 port = hdr->source;
 499                 new_port = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_port;
 500                 hdr->source = new_port;
 501                 break;
 502         }
 503
 504         nf_flow_nat_port(skb, thoff, protocol, port, new_port);
 505 }
 506 EXPORT_SYMBOL_GPL(nf_flow_dnat_port);
 507
 508 int nf_flow_table_init(struct nf_flowtable *flowtable)
 509 {
 510         int err;
 511
 512         INIT_DEFERRABLE_WORK(&flowtable->gc_work, nf_flow_offload_work_gc);
 513         flow_block_init(&flowtable->flow_block);
 514         init_rwsem(&flowtable->flow_block_lock);
 515
 516         err = rhashtable_init(&flowtable->rhashtable,
 517                               &nf_flow_offload_rhash_params);
 518         if (err < 0)
 519                 return err;
 520
 521         queue_delayed_work(system_power_efficient_wq,
 522                            &flowtable->gc_work, HZ);
 523
 524         mutex_lock(&flowtable_lock);
 525         list_add(&flowtable->list, &flowtables);
 526         mutex_unlock(&flowtable_lock);
 527
 528         return 0;
 529 }
 530 EXPORT_SYMBOL_GPL(nf_flow_table_init);
 531
 532 static void nf_flow_table_do_cleanup(struct flow_offload *flow, void *data)
 533 {
 534         struct net_device *dev = data;
 535
 536         if (!dev) {
 537                 flow_offload_teardown(flow);
 538                 return;
 539         }
 540
 541         if (net_eq(nf_ct_net(flow->ct), dev_net(dev)) &&
 542             (flow->tuplehash[0].tuple.iifidx == dev->ifindex ||
 543              flow->tuplehash[1].tuple.iifidx == dev->ifindex))
 544                 flow_offload_teardown(flow);
 545 }
 546
 547 void nf_flow_table_gc_cleanup(struct nf_flowtable *flowtable,
 548                               struct net_device *dev)
 549 {
 550         nf_flow_table_iterate(flowtable, nf_flow_table_do_cleanup, dev);
 551         flush_delayed_work(&flowtable->gc_work);
 552         nf_flow_table_offload_flush(flowtable);
 553 }
 554
 555 void nf_flow_table_cleanup(struct net_device *dev)
 556 {
 557         struct nf_flowtable *flowtable;
 558
 559         mutex_lock(&flowtable_lock);
 560         list_for_each_entry(flowtable, &flowtables, list)
 561                 nf_flow_table_gc_cleanup(flowtable, dev);
 562         mutex_unlock(&flowtable_lock);
 563 }
 564 EXPORT_SYMBOL_GPL(nf_flow_table_cleanup);
 565
 566 void nf_flow_table_free(struct nf_flowtable *flow_table)
 567 {
 568         mutex_lock(&flowtable_lock);
 569         list_del(&flow_table->list);
 570         mutex_unlock(&flowtable_lock);
 571
 572         cancel_delayed_work_sync(&flow_table->gc_work);
 573         nf_flow_table_iterate(flow_table, nf_flow_table_do_cleanup, NULL);
 574         nf_flow_table_iterate(flow_table, nf_flow_offload_gc_step, flow_table);
 575         nf_flow_table_offload_flush(flow_table);
 576         if (nf_flowtable_hw_offload(flow_table))
 577                 nf_flow_table_iterate(flow_table, nf_flow_offload_gc_step,
 578                                       flow_table);
 579         rhashtable_destroy(&flow_table->rhashtable);
 580 }
 581 EXPORT_SYMBOL_GPL(nf_flow_table_free);
 582
 583 static int __init nf_flow_table_module_init(void)
 584 {
 585         return nf_flow_table_offload_init();
 586 }
 587
 588 static void __exit nf_flow_table_module_exit(void)
 589 {
 590         nf_flow_table_offload_exit();
 591 }
 592
 593 module_init(nf_flow_table_module_init);
 594 module_exit(nf_flow_table_module_exit);
 595
 596 MODULE_LICENSE("GPL");
 597 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 598 MODULE_DESCRIPTION("Netfilter flow table module");