target/linux/generic/hack-5.4/650-netfilter-add-xt_OFFLOAD-target.patch

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Tue, 20 Feb 2018 15:56:02 +0100
   3 Subject: [PATCH] netfilter: add xt_OFFLOAD target
   4
   5 Signed-off-by: Felix Fietkau <nbd@nbd.name>
   6 ---
   7  create mode 100644 net/netfilter/xt_OFFLOAD.c
   8
   9 --- a/net/ipv4/netfilter/Kconfig
  10 +++ b/net/ipv4/netfilter/Kconfig
  11 @@ -56,8 +56,6 @@ config NF_TABLES_ARP
  12         help
  13           This option enables the ARP support for nf_tables.
  14
  15 -endif # NF_TABLES
  16 -
  17  config NF_FLOW_TABLE_IPV4
  18         tristate "Netfilter flow table IPv4 module"
  19         depends on NF_FLOW_TABLE
  20 @@ -66,6 +64,8 @@ config NF_FLOW_TABLE_IPV4
  21
  22           To compile it as a module, choose M here.
  23
  24 +endif # NF_TABLES
  25 +
  26  config NF_DUP_IPV4
  27         tristate "Netfilter IPv4 packet duplication to alternate destination"
  28         depends on !NF_CONNTRACK || NF_CONNTRACK
  29 --- a/net/ipv6/netfilter/Kconfig
  30 +++ b/net/ipv6/netfilter/Kconfig
  31 @@ -45,7 +45,6 @@ config NFT_FIB_IPV6
  32           multicast or blackhole.
  33
  34  endif # NF_TABLES_IPV6
  35 -endif # NF_TABLES
  36
  37  config NF_FLOW_TABLE_IPV6
  38         tristate "Netfilter flow table IPv6 module"
  39 @@ -55,6 +54,8 @@ config NF_FLOW_TABLE_IPV6
  40
  41           To compile it as a module, choose M here.
  42
  43 +endif # NF_TABLES
  44 +
  45  config NF_DUP_IPV6
  46         tristate "Netfilter IPv6 packet duplication to alternate destination"
  47         depends on !NF_CONNTRACK || NF_CONNTRACK
  48 --- a/net/netfilter/Kconfig
  49 +++ b/net/netfilter/Kconfig
  50 @@ -702,8 +702,6 @@ config NFT_FIB_NETDEV
  51
  52  endif # NF_TABLES_NETDEV
  53
  54 -endif # NF_TABLES
  55 -
  56  config NF_FLOW_TABLE_INET
  57         tristate "Netfilter flow table mixed IPv4/IPv6 module"
  58         depends on NF_FLOW_TABLE
  59 @@ -712,11 +710,12 @@ config NF_FLOW_TABLE_INET
  60
  61           To compile it as a module, choose M here.
  62
  63 +endif # NF_TABLES
  64 +
  65  config NF_FLOW_TABLE
  66         tristate "Netfilter flow table module"
  67         depends on NETFILTER_INGRESS
  68         depends on NF_CONNTRACK
  69 -       depends on NF_TABLES
  70         help
  71           This option adds the flow table core infrastructure.
  72
  73 @@ -1005,6 +1004,15 @@ config NETFILTER_XT_TARGET_NOTRACK
  74         depends on NETFILTER_ADVANCED
  75         select NETFILTER_XT_TARGET_CT
  76
  77 +config NETFILTER_XT_TARGET_FLOWOFFLOAD
  78 +       tristate '"FLOWOFFLOAD" target support'
  79 +       depends on NF_FLOW_TABLE
  80 +       depends on NETFILTER_INGRESS
  81 +       help
  82 +         This option adds a `FLOWOFFLOAD' target, which uses the nf_flow_offload
  83 +         module to speed up processing of packets by bypassing the usual
  84 +         netfilter chains
  85 +
  86  config NETFILTER_XT_TARGET_RATEEST
  87         tristate '"RATEEST" target support'
  88         depends on NETFILTER_ADVANCED
  89 --- a/net/netfilter/Makefile
  90 +++ b/net/netfilter/Makefile
  91 @@ -144,6 +144,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_CLASSIF
  92  obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o
  93  obj-$(CONFIG_NETFILTER_XT_TARGET_CT) += xt_CT.o
  94  obj-$(CONFIG_NETFILTER_XT_TARGET_DSCP) += xt_DSCP.o
  95 +obj-$(CONFIG_NETFILTER_XT_TARGET_FLOWOFFLOAD) += xt_FLOWOFFLOAD.o
  96  obj-$(CONFIG_NETFILTER_XT_TARGET_HL) += xt_HL.o
  97  obj-$(CONFIG_NETFILTER_XT_TARGET_HMARK) += xt_HMARK.o
  98  obj-$(CONFIG_NETFILTER_XT_TARGET_LED) += xt_LED.o
  99 --- /dev/null
 100 +++ b/net/netfilter/xt_FLOWOFFLOAD.c
 101 @@ -0,0 +1,427 @@
 102 +/*
 103 + * Copyright (C) 2018 Felix Fietkau <nbd@nbd.name>
 104 + *
 105 + * This program is free software; you can redistribute it and/or modify
 106 + * it under the terms of the GNU General Public License version 2 as
 107 + * published by the Free Software Foundation.
 108 + */
 109 +#include <linux/module.h>
 110 +#include <linux/init.h>
 111 +#include <linux/netfilter.h>
 112 +#include <linux/netfilter/xt_FLOWOFFLOAD.h>
 113 +#include <net/ip.h>
 114 +#include <net/netfilter/nf_conntrack.h>
 115 +#include <net/netfilter/nf_conntrack_extend.h>
 116 +#include <net/netfilter/nf_conntrack_helper.h>
 117 +#include <net/netfilter/nf_flow_table.h>
 118 +
 119 +static struct nf_flowtable nf_flowtable;
 120 +static HLIST_HEAD(hooks);
 121 +static DEFINE_SPINLOCK(hooks_lock);
 122 +static struct delayed_work hook_work;
 123 +
 124 +struct xt_flowoffload_hook {
 125 +       struct hlist_node list;
 126 +       struct nf_hook_ops ops;
 127 +       struct net *net;
 128 +       bool registered;
 129 +       bool used;
 130 +};
 131 +
 132 +static unsigned int
 133 +xt_flowoffload_net_hook(void *priv, struct sk_buff *skb,
 134 +                         const struct nf_hook_state *state)
 135 +{
 136 +       switch (skb->protocol) {
 137 +       case htons(ETH_P_IP):
 138 +               return nf_flow_offload_ip_hook(priv, skb, state);
 139 +       case htons(ETH_P_IPV6):
 140 +               return nf_flow_offload_ipv6_hook(priv, skb, state);
 141 +       }
 142 +
 143 +       return NF_ACCEPT;
 144 +}
 145 +
 146 +int nf_flow_table_iterate(struct nf_flowtable *flow_table,
 147 +                          void (*iter)(struct flow_offload *flow, void *data),
 148 +                          void *data);
 149 +
 150 +static int
 151 +xt_flowoffload_create_hook(struct net_device *dev)
 152 +{
 153 +       struct xt_flowoffload_hook *hook;
 154 +       struct nf_hook_ops *ops;
 155 +
 156 +       hook = kzalloc(sizeof(*hook), GFP_ATOMIC);
 157 +       if (!hook)
 158 +               return -ENOMEM;
 159 +
 160 +       ops = &hook->ops;
 161 +       ops->pf = NFPROTO_NETDEV;
 162 +       ops->hooknum = NF_NETDEV_INGRESS;
 163 +       ops->priority = 10;
 164 +       ops->priv = &nf_flowtable;
 165 +       ops->hook = xt_flowoffload_net_hook;
 166 +       ops->dev = dev;
 167 +
 168 +       hlist_add_head(&hook->list, &hooks);
 169 +       mod_delayed_work(system_power_efficient_wq, &hook_work, 0);
 170 +
 171 +       return 0;
 172 +}
 173 +
 174 +static struct xt_flowoffload_hook *
 175 +flow_offload_lookup_hook(struct net_device *dev)
 176 +{
 177 +       struct xt_flowoffload_hook *hook;
 178 +
 179 +       hlist_for_each_entry(hook, &hooks, list) {
 180 +               if (hook->ops.dev == dev)
 181 +                       return hook;
 182 +       }
 183 +
 184 +       return NULL;
 185 +}
 186 +
 187 +static void
 188 +xt_flowoffload_check_device(struct net_device *dev)
 189 +{
 190 +       struct xt_flowoffload_hook *hook;
 191 +
 192 +       spin_lock_bh(&hooks_lock);
 193 +       hook = flow_offload_lookup_hook(dev);
 194 +       if (hook)
 195 +               hook->used = true;
 196 +       else
 197 +               xt_flowoffload_create_hook(dev);
 198 +       spin_unlock_bh(&hooks_lock);
 199 +}
 200 +
 201 +static void
 202 +xt_flowoffload_register_hooks(void)
 203 +{
 204 +       struct xt_flowoffload_hook *hook;
 205 +
 206 +restart:
 207 +       hlist_for_each_entry(hook, &hooks, list) {
 208 +               if (hook->registered)
 209 +                       continue;
 210 +
 211 +               hook->registered = true;
 212 +               hook->net = dev_net(hook->ops.dev);
 213 +               spin_unlock_bh(&hooks_lock);
 214 +               nf_register_net_hook(hook->net, &hook->ops);
 215 +               spin_lock_bh(&hooks_lock);
 216 +               goto restart;
 217 +       }
 218 +
 219 +}
 220 +
 221 +static void
 222 +xt_flowoffload_cleanup_hooks(void)
 223 +{
 224 +       struct xt_flowoffload_hook *hook;
 225 +
 226 +restart:
 227 +       hlist_for_each_entry(hook, &hooks, list) {
 228 +               if (hook->used || !hook->registered)
 229 +                       continue;
 230 +
 231 +               hlist_del(&hook->list);
 232 +               spin_unlock_bh(&hooks_lock);
 233 +               nf_unregister_net_hook(hook->net, &hook->ops);
 234 +               kfree(hook);
 235 +               spin_lock_bh(&hooks_lock);
 236 +               goto restart;
 237 +       }
 238 +
 239 +}
 240 +
 241 +static void
 242 +xt_flowoffload_check_hook(struct flow_offload *flow, void *data)
 243 +{
 244 +       struct flow_offload_tuple *tuple = &flow->tuplehash[0].tuple;
 245 +       struct xt_flowoffload_hook *hook;
 246 +       bool *found = data;
 247 +       struct rtable *rt = (struct rtable *)tuple->dst_cache;
 248 +
 249 +       spin_lock_bh(&hooks_lock);
 250 +       hlist_for_each_entry(hook, &hooks, list) {
 251 +               if (hook->ops.dev->ifindex != tuple->iifidx &&
 252 +                   hook->ops.dev->ifindex != rt->dst.dev->ifindex)
 253 +                       continue;
 254 +
 255 +               hook->used = true;
 256 +               *found = true;
 257 +       }
 258 +       spin_unlock_bh(&hooks_lock);
 259 +}
 260 +
 261 +static void
 262 +xt_flowoffload_hook_work(struct work_struct *work)
 263 +{
 264 +       struct xt_flowoffload_hook *hook;
 265 +       bool found = false;
 266 +       int err;
 267 +
 268 +       spin_lock_bh(&hooks_lock);
 269 +       xt_flowoffload_register_hooks();
 270 +       hlist_for_each_entry(hook, &hooks, list)
 271 +               hook->used = false;
 272 +       spin_unlock_bh(&hooks_lock);
 273 +
 274 +       err = nf_flow_table_iterate(&nf_flowtable, xt_flowoffload_check_hook,
 275 +                                   &found);
 276 +       if (err && err != -EAGAIN)
 277 +           goto out;
 278 +
 279 +       spin_lock_bh(&hooks_lock);
 280 +       xt_flowoffload_cleanup_hooks();
 281 +       spin_unlock_bh(&hooks_lock);
 282 +
 283 +out:
 284 +       if (found)
 285 +               queue_delayed_work(system_power_efficient_wq, &hook_work, HZ);
 286 +}
 287 +
 288 +static bool
 289 +xt_flowoffload_skip(struct sk_buff *skb, int family)
 290 +{
 291 +       if (skb_sec_path(skb))
 292 +               return true;
 293 +
 294 +       if (family == NFPROTO_IPV4) {
 295 +               const struct ip_options *opt = &(IPCB(skb)->opt);
 296 +
 297 +               if (unlikely(opt->optlen))
 298 +                       return true;
 299 +       }
 300 +
 301 +       return false;
 302 +}
 303 +
 304 +static struct dst_entry *
 305 +xt_flowoffload_dst(const struct nf_conn *ct, enum ip_conntrack_dir dir,
 306 +                  const struct xt_action_param *par, int ifindex)
 307 +{
 308 +       struct dst_entry *dst = NULL;
 309 +       struct flowi fl;
 310 +
 311 +       memset(&fl, 0, sizeof(fl));
 312 +       switch (xt_family(par)) {
 313 +       case NFPROTO_IPV4:
 314 +               fl.u.ip4.daddr = ct->tuplehash[dir].tuple.src.u3.ip;
 315 +               fl.u.ip4.flowi4_oif = ifindex;
 316 +               break;
 317 +       case NFPROTO_IPV6:
 318 +               fl.u.ip6.saddr = ct->tuplehash[dir].tuple.dst.u3.in6;
 319 +               fl.u.ip6.daddr = ct->tuplehash[dir].tuple.src.u3.in6;
 320 +               fl.u.ip6.flowi6_oif = ifindex;
 321 +               break;
 322 +       }
 323 +
 324 +       nf_route(xt_net(par), &dst, &fl, false, xt_family(par));
 325 +
 326 +       return dst;
 327 +}
 328 +
 329 +static int
 330 +xt_flowoffload_route(struct sk_buff *skb, const struct nf_conn *ct,
 331 +                  const struct xt_action_param *par,
 332 +                  struct nf_flow_route *route, enum ip_conntrack_dir dir)
 333 +{
 334 +       struct dst_entry *this_dst, *other_dst;
 335 +
 336 +       this_dst = xt_flowoffload_dst(ct, !dir, par, xt_out(par)->ifindex);
 337 +       other_dst = xt_flowoffload_dst(ct, dir, par, xt_in(par)->ifindex);
 338 +
 339 +       route->tuple[dir].dst           = this_dst;
 340 +       route->tuple[!dir].dst          = other_dst;
 341 +
 342 +       if (!this_dst || !other_dst)
 343 +               return -ENOENT;
 344 +
 345 +       if (dst_xfrm(this_dst) || dst_xfrm(other_dst))
 346 +               return -EINVAL;
 347 +
 348 +       return 0;
 349 +}
 350 +
 351 +static unsigned int
 352 +flowoffload_tg(struct sk_buff *skb, const struct xt_action_param *par)
 353 +{
 354 +       const struct xt_flowoffload_target_info *info = par->targinfo;
 355 +       struct tcphdr _tcph, *tcph = NULL;
 356 +       enum ip_conntrack_info ctinfo;
 357 +       enum ip_conntrack_dir dir;
 358 +       struct nf_flow_route route;
 359 +       struct flow_offload *flow = NULL;
 360 +       struct nf_conn *ct;
 361 +       struct net *net;
 362 +
 363 +       if (xt_flowoffload_skip(skb, xt_family(par)))
 364 +               return XT_CONTINUE;
 365 +
 366 +       ct = nf_ct_get(skb, &ctinfo);
 367 +       if (ct == NULL)
 368 +               return XT_CONTINUE;
 369 +
 370 +       switch (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum) {
 371 +       case IPPROTO_TCP:
 372 +               if (ct->proto.tcp.state != TCP_CONNTRACK_ESTABLISHED)
 373 +                       return XT_CONTINUE;
 374 +
 375 +               tcph = skb_header_pointer(skb, par->thoff,
 376 +                                         sizeof(_tcph), &_tcph);
 377 +               if (unlikely(!tcph || tcph->fin || tcph->rst))
 378 +                       return XT_CONTINUE;
 379 +               break;
 380 +       case IPPROTO_UDP:
 381 +               break;
 382 +       default:
 383 +               return XT_CONTINUE;
 384 +       }
 385 +
 386 +       if (nf_ct_ext_exist(ct, NF_CT_EXT_HELPER) ||
 387 +           ct->status & IPS_SEQ_ADJUST)
 388 +               return XT_CONTINUE;
 389 +
 390 +       if (!nf_ct_is_confirmed(ct))
 391 +               return XT_CONTINUE;
 392 +
 393 +       if (!xt_in(par) || !xt_out(par))
 394 +               return XT_CONTINUE;
 395 +
 396 +       if (test_and_set_bit(IPS_OFFLOAD_BIT, &ct->status))
 397 +               return XT_CONTINUE;
 398 +
 399 +       dir = CTINFO2DIR(ctinfo);
 400 +
 401 +       if (xt_flowoffload_route(skb, ct, par, &route, dir) == 0)
 402 +               flow = flow_offload_alloc(ct, &route);
 403 +
 404 +       dst_release(route.tuple[dir].dst);
 405 +       dst_release(route.tuple[!dir].dst);
 406 +
 407 +       if (!flow)
 408 +               goto err_flow_route;
 409 +
 410 +       if (tcph) {
 411 +               ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
 412 +               ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
 413 +       }
 414 +
 415 +       if (flow_offload_add(&nf_flowtable, flow) < 0)
 416 +               goto err_flow_add;
 417 +
 418 +       xt_flowoffload_check_device(xt_in(par));
 419 +       xt_flowoffload_check_device(xt_out(par));
 420 +
 421 +       net = read_pnet(&nf_flowtable.ft_net);
 422 +       if (!net)
 423 +               write_pnet(&nf_flowtable.ft_net, xt_net(par));
 424 +
 425 +       if (info->flags & XT_FLOWOFFLOAD_HW)
 426 +               nf_flow_offload_hw_add(xt_net(par), flow, ct);
 427 +
 428 +       return XT_CONTINUE;
 429 +
 430 +err_flow_add:
 431 +       flow_offload_free(flow);
 432 +err_flow_route:
 433 +       clear_bit(IPS_OFFLOAD_BIT, &ct->status);
 434 +       return XT_CONTINUE;
 435 +}
 436 +
 437 +
 438 +static int flowoffload_chk(const struct xt_tgchk_param *par)
 439 +{
 440 +       struct xt_flowoffload_target_info *info = par->targinfo;
 441 +
 442 +       if (info->flags & ~XT_FLOWOFFLOAD_MASK)
 443 +               return -EINVAL;
 444 +
 445 +       return 0;
 446 +}
 447 +
 448 +static struct xt_target offload_tg_reg __read_mostly = {
 449 +       .family         = NFPROTO_UNSPEC,
 450 +       .name           = "FLOWOFFLOAD",
 451 +       .revision       = 0,
 452 +       .targetsize     = sizeof(struct xt_flowoffload_target_info),
 453 +       .usersize       = sizeof(struct xt_flowoffload_target_info),
 454 +       .checkentry     = flowoffload_chk,
 455 +       .target         = flowoffload_tg,
 456 +       .me             = THIS_MODULE,
 457 +};
 458 +
 459 +static int xt_flowoffload_table_init(struct nf_flowtable *table)
 460 +{
 461 +       table->flags = NF_FLOWTABLE_F_HW;
 462 +       nf_flow_table_init(table);
 463 +       return 0;
 464 +}
 465 +
 466 +static void xt_flowoffload_table_cleanup(struct nf_flowtable *table)
 467 +{
 468 +       nf_flow_table_free(table);
 469 +}
 470 +
 471 +static int flow_offload_netdev_event(struct notifier_block *this,
 472 +                                    unsigned long event, void *ptr)
 473 +{
 474 +       struct xt_flowoffload_hook *hook = NULL;
 475 +       struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 476 +
 477 +       if (event != NETDEV_UNREGISTER)
 478 +               return NOTIFY_DONE;
 479 +
 480 +       spin_lock_bh(&hooks_lock);
 481 +       hook = flow_offload_lookup_hook(dev);
 482 +       if (hook) {
 483 +               hlist_del(&hook->list);
 484 +       }
 485 +       spin_unlock_bh(&hooks_lock);
 486 +       if (hook) {
 487 +               nf_unregister_net_hook(hook->net, &hook->ops);
 488 +               kfree(hook);
 489 +       }
 490 +
 491 +       nf_flow_table_cleanup(dev);
 492 +
 493 +       return NOTIFY_DONE;
 494 +}
 495 +
 496 +static struct notifier_block flow_offload_netdev_notifier = {
 497 +       .notifier_call  = flow_offload_netdev_event,
 498 +};
 499 +
 500 +static int __init xt_flowoffload_tg_init(void)
 501 +{
 502 +       int ret;
 503 +
 504 +       register_netdevice_notifier(&flow_offload_netdev_notifier);
 505 +
 506 +       INIT_DELAYED_WORK(&hook_work, xt_flowoffload_hook_work);
 507 +
 508 +       ret = xt_flowoffload_table_init(&nf_flowtable);
 509 +       if (ret)
 510 +               return ret;
 511 +
 512 +       ret = xt_register_target(&offload_tg_reg);
 513 +       if (ret)
 514 +               xt_flowoffload_table_cleanup(&nf_flowtable);
 515 +
 516 +       return ret;
 517 +}
 518 +
 519 +static void __exit xt_flowoffload_tg_exit(void)
 520 +{
 521 +       xt_unregister_target(&offload_tg_reg);
 522 +       xt_flowoffload_table_cleanup(&nf_flowtable);
 523 +       unregister_netdevice_notifier(&flow_offload_netdev_notifier);
 524 +}
 525 +
 526 +MODULE_LICENSE("GPL");
 527 +module_init(xt_flowoffload_tg_init);
 528 +module_exit(xt_flowoffload_tg_exit);
 529 --- a/net/netfilter/nf_flow_table_core.c
 530 +++ b/net/netfilter/nf_flow_table_core.c
 531 @@ -7,7 +7,6 @@
 532  #include <linux/netdevice.h>
 533  #include <net/ip.h>
 534  #include <net/ip6_route.h>
 535 -#include <net/netfilter/nf_tables.h>
 536  #include <net/netfilter/nf_flow_table.h>
 537  #include <net/netfilter/nf_conntrack.h>
 538  #include <net/netfilter/nf_conntrack_core.h>
 539 @@ -338,8 +337,7 @@ flow_offload_lookup(struct nf_flowtable
 540  }
 541  EXPORT_SYMBOL_GPL(flow_offload_lookup);
 542
 543 -static int
 544 -nf_flow_table_iterate(struct nf_flowtable *flow_table,
 545 +int nf_flow_table_iterate(struct nf_flowtable *flow_table,
 546                       void (*iter)(struct flow_offload *flow, void *data),
 547                       void *data)
 548  {
 549 @@ -372,6 +370,7 @@ nf_flow_table_iterate(struct nf_flowtabl
 550
 551         return err;
 552  }
 553 +EXPORT_SYMBOL_GPL(nf_flow_table_iterate);
 554
 555  static void nf_flow_offload_gc_step(struct flow_offload *flow, void *data)
 556  {
 557 --- /dev/null
 558 +++ b/include/uapi/linux/netfilter/xt_FLOWOFFLOAD.h
 559 @@ -0,0 +1,17 @@
 560 +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
 561 +#ifndef _XT_FLOWOFFLOAD_H
 562 +#define _XT_FLOWOFFLOAD_H
 563 +
 564 +#include <linux/types.h>
 565 +
 566 +enum {
 567 +       XT_FLOWOFFLOAD_HW       = 1 << 0,
 568 +
 569 +       XT_FLOWOFFLOAD_MASK     = XT_FLOWOFFLOAD_HW
 570 +};
 571 +
 572 +struct xt_flowoffload_target_info {
 573 +       __u32 flags;
 574 +};
 575 +
 576 +#endif /* _XT_FLOWOFFLOAD_H */
 577 --- a/include/net/netfilter/nf_flow_table.h
 578 +++ b/include/net/netfilter/nf_flow_table.h
 579 @@ -130,6 +130,10 @@ static inline void flow_offload_dead(str
 580         flow->flags |= FLOW_OFFLOAD_DYING;
 581  }
 582
 583 +int nf_flow_table_iterate(struct nf_flowtable *flow_table,
 584 +                      void (*iter)(struct flow_offload *flow, void *data),
 585 +                      void *data);
 586 +
 587  int nf_flow_snat_port(const struct flow_offload *flow,
 588                       struct sk_buff *skb, unsigned int thoff,
 589                       u8 protocol, enum flow_offload_tuple_dir dir);