net/sched/act_csum.c

   1 /*
   2  * Checksum updating actions
   3  *
   4  * Copyright (c) 2010 Gregoire Baron <baronchon@n7mm.org>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the Free
   8  * Software Foundation; either version 2 of the License, or (at your option)
   9  * any later version.
  10  *
  11  */
  12
  13 #include <linux/types.h>
  14 #include <linux/init.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/spinlock.h>
  18
  19 #include <linux/netlink.h>
  20 #include <net/netlink.h>
  21 #include <linux/rtnetlink.h>
  22
  23 #include <linux/skbuff.h>
  24
  25 #include <net/ip.h>
  26 #include <net/ipv6.h>
  27 #include <net/icmp.h>
  28 #include <linux/icmpv6.h>
  29 #include <linux/igmp.h>
  30 #include <net/tcp.h>
  31 #include <net/udp.h>
  32 #include <net/ip6_checksum.h>
  33 #include <net/sctp/checksum.h>
  34
  35 #include <net/act_api.h>
  36
  37 #include <linux/tc_act/tc_csum.h>
  38 #include <net/tc_act/tc_csum.h>
  39
  40 static const struct nla_policy csum_policy[TCA_CSUM_MAX + 1] = {
  41         [TCA_CSUM_PARMS] = { .len = sizeof(struct tc_csum), },
  42 };
  43
  44 static unsigned int csum_net_id;
  45 static struct tc_action_ops act_csum_ops;
  46
  47 static int tcf_csum_init(struct net *net, struct nlattr *nla,
  48                          struct nlattr *est, struct tc_action **a, int ovr,
  49                          int bind)
  50 {
  51         struct tc_action_net *tn = net_generic(net, csum_net_id);
  52         struct nlattr *tb[TCA_CSUM_MAX + 1];
  53         struct tc_csum *parm;
  54         struct tcf_csum *p;
  55         int ret = 0, err;
  56
  57         if (nla == NULL)
  58                 return -EINVAL;
  59
  60         err = nla_parse_nested(tb, TCA_CSUM_MAX, nla, csum_policy, NULL);
  61         if (err < 0)
  62                 return err;
  63
  64         if (tb[TCA_CSUM_PARMS] == NULL)
  65                 return -EINVAL;
  66         parm = nla_data(tb[TCA_CSUM_PARMS]);
  67
  68         if (!tcf_idr_check(tn, parm->index, a, bind)) {
  69                 ret = tcf_idr_create(tn, parm->index, est, a,
  70                                      &act_csum_ops, bind, false);
  71                 if (ret)
  72                         return ret;
  73                 ret = ACT_P_CREATED;
  74         } else {
  75                 if (bind)/* dont override defaults */
  76                         return 0;
  77                 tcf_idr_release(*a, bind);
  78                 if (!ovr)
  79                         return -EEXIST;
  80         }
  81
  82         p = to_tcf_csum(*a);
  83         spin_lock_bh(&p->tcf_lock);
  84         p->tcf_action = parm->action;
  85         p->update_flags = parm->update_flags;
  86         spin_unlock_bh(&p->tcf_lock);
  87
  88         if (ret == ACT_P_CREATED)
  89                 tcf_idr_insert(tn, *a);
  90
  91         return ret;
  92 }
  93
  94 /**
  95  * tcf_csum_skb_nextlayer - Get next layer pointer
  96  * @skb: sk_buff to use
  97  * @ihl: previous summed headers length
  98  * @ipl: complete packet length
  99  * @jhl: next header length
 100  *
 101  * Check the expected next layer availability in the specified sk_buff.
 102  * Return the next layer pointer if pass, NULL otherwise.
 103  */
 104 static void *tcf_csum_skb_nextlayer(struct sk_buff *skb,
 105                                     unsigned int ihl, unsigned int ipl,
 106                                     unsigned int jhl)
 107 {
 108         int ntkoff = skb_network_offset(skb);
 109         int hl = ihl + jhl;
 110
 111         if (!pskb_may_pull(skb, ipl + ntkoff) || (ipl < hl) ||
 112             skb_try_make_writable(skb, hl + ntkoff))
 113                 return NULL;
 114         else
 115                 return (void *)(skb_network_header(skb) + ihl);
 116 }
 117
 118 static int tcf_csum_ipv4_icmp(struct sk_buff *skb, unsigned int ihl,
 119                               unsigned int ipl)
 120 {
 121         struct icmphdr *icmph;
 122
 123         icmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmph));
 124         if (icmph == NULL)
 125                 return 0;
 126
 127         icmph->checksum = 0;
 128         skb->csum = csum_partial(icmph, ipl - ihl, 0);
 129         icmph->checksum = csum_fold(skb->csum);
 130
 131         skb->ip_summed = CHECKSUM_NONE;
 132
 133         return 1;
 134 }
 135
 136 static int tcf_csum_ipv4_igmp(struct sk_buff *skb,
 137                               unsigned int ihl, unsigned int ipl)
 138 {
 139         struct igmphdr *igmph;
 140
 141         igmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*igmph));
 142         if (igmph == NULL)
 143                 return 0;
 144
 145         igmph->csum = 0;
 146         skb->csum = csum_partial(igmph, ipl - ihl, 0);
 147         igmph->csum = csum_fold(skb->csum);
 148
 149         skb->ip_summed = CHECKSUM_NONE;
 150
 151         return 1;
 152 }
 153
 154 static int tcf_csum_ipv6_icmp(struct sk_buff *skb, unsigned int ihl,
 155                               unsigned int ipl)
 156 {
 157         struct icmp6hdr *icmp6h;
 158         const struct ipv6hdr *ip6h;
 159
 160         icmp6h = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmp6h));
 161         if (icmp6h == NULL)
 162                 return 0;
 163
 164         ip6h = ipv6_hdr(skb);
 165         icmp6h->icmp6_cksum = 0;
 166         skb->csum = csum_partial(icmp6h, ipl - ihl, 0);
 167         icmp6h->icmp6_cksum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 168                                               ipl - ihl, IPPROTO_ICMPV6,
 169                                               skb->csum);
 170
 171         skb->ip_summed = CHECKSUM_NONE;
 172
 173         return 1;
 174 }
 175
 176 static int tcf_csum_ipv4_tcp(struct sk_buff *skb, unsigned int ihl,
 177                              unsigned int ipl)
 178 {
 179         struct tcphdr *tcph;
 180         const struct iphdr *iph;
 181
 182         if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
 183                 return 1;
 184
 185         tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph));
 186         if (tcph == NULL)
 187                 return 0;
 188
 189         iph = ip_hdr(skb);
 190         tcph->check = 0;
 191         skb->csum = csum_partial(tcph, ipl - ihl, 0);
 192         tcph->check = tcp_v4_check(ipl - ihl,
 193                                    iph->saddr, iph->daddr, skb->csum);
 194
 195         skb->ip_summed = CHECKSUM_NONE;
 196
 197         return 1;
 198 }
 199
 200 static int tcf_csum_ipv6_tcp(struct sk_buff *skb, unsigned int ihl,
 201                              unsigned int ipl)
 202 {
 203         struct tcphdr *tcph;
 204         const struct ipv6hdr *ip6h;
 205
 206         if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
 207                 return 1;
 208
 209         tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph));
 210         if (tcph == NULL)
 211                 return 0;
 212
 213         ip6h = ipv6_hdr(skb);
 214         tcph->check = 0;
 215         skb->csum = csum_partial(tcph, ipl - ihl, 0);
 216         tcph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 217                                       ipl - ihl, IPPROTO_TCP,
 218                                       skb->csum);
 219
 220         skb->ip_summed = CHECKSUM_NONE;
 221
 222         return 1;
 223 }
 224
 225 static int tcf_csum_ipv4_udp(struct sk_buff *skb, unsigned int ihl,
 226                              unsigned int ipl, int udplite)
 227 {
 228         struct udphdr *udph;
 229         const struct iphdr *iph;
 230         u16 ul;
 231
 232         /*
 233          * Support both UDP and UDPLITE checksum algorithms, Don't use
 234          * udph->len to get the real length without any protocol check,
 235          * UDPLITE uses udph->len for another thing,
 236          * Use iph->tot_len, or just ipl.
 237          */
 238
 239         udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph));
 240         if (udph == NULL)
 241                 return 0;
 242
 243         iph = ip_hdr(skb);
 244         ul = ntohs(udph->len);
 245
 246         if (udplite || udph->check) {
 247
 248                 udph->check = 0;
 249
 250                 if (udplite) {
 251                         if (ul == 0)
 252                                 skb->csum = csum_partial(udph, ipl - ihl, 0);
 253                         else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl))
 254                                 skb->csum = csum_partial(udph, ul, 0);
 255                         else
 256                                 goto ignore_obscure_skb;
 257                 } else {
 258                         if (ul != ipl - ihl)
 259                                 goto ignore_obscure_skb;
 260
 261                         skb->csum = csum_partial(udph, ul, 0);
 262                 }
 263
 264                 udph->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
 265                                                 ul, iph->protocol,
 266                                                 skb->csum);
 267
 268                 if (!udph->check)
 269                         udph->check = CSUM_MANGLED_0;
 270         }
 271
 272         skb->ip_summed = CHECKSUM_NONE;
 273
 274 ignore_obscure_skb:
 275         return 1;
 276 }
 277
 278 static int tcf_csum_ipv6_udp(struct sk_buff *skb, unsigned int ihl,
 279                              unsigned int ipl, int udplite)
 280 {
 281         struct udphdr *udph;
 282         const struct ipv6hdr *ip6h;
 283         u16 ul;
 284
 285         /*
 286          * Support both UDP and UDPLITE checksum algorithms, Don't use
 287          * udph->len to get the real length without any protocol check,
 288          * UDPLITE uses udph->len for another thing,
 289          * Use ip6h->payload_len + sizeof(*ip6h) ... , or just ipl.
 290          */
 291
 292         udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph));
 293         if (udph == NULL)
 294                 return 0;
 295
 296         ip6h = ipv6_hdr(skb);
 297         ul = ntohs(udph->len);
 298
 299         udph->check = 0;
 300
 301         if (udplite) {
 302                 if (ul == 0)
 303                         skb->csum = csum_partial(udph, ipl - ihl, 0);
 304
 305                 else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl))
 306                         skb->csum = csum_partial(udph, ul, 0);
 307
 308                 else
 309                         goto ignore_obscure_skb;
 310         } else {
 311                 if (ul != ipl - ihl)
 312                         goto ignore_obscure_skb;
 313
 314                 skb->csum = csum_partial(udph, ul, 0);
 315         }
 316
 317         udph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, ul,
 318                                       udplite ? IPPROTO_UDPLITE : IPPROTO_UDP,
 319                                       skb->csum);
 320
 321         if (!udph->check)
 322                 udph->check = CSUM_MANGLED_0;
 323
 324         skb->ip_summed = CHECKSUM_NONE;
 325
 326 ignore_obscure_skb:
 327         return 1;
 328 }
 329
 330 static int tcf_csum_sctp(struct sk_buff *skb, unsigned int ihl,
 331                          unsigned int ipl)
 332 {
 333         struct sctphdr *sctph;
 334
 335         if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_SCTP)
 336                 return 1;
 337
 338         sctph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*sctph));
 339         if (!sctph)
 340                 return 0;
 341
 342         sctph->checksum = sctp_compute_cksum(skb,
 343                                              skb_network_offset(skb) + ihl);
 344         skb->ip_summed = CHECKSUM_NONE;
 345         skb->csum_not_inet = 0;
 346
 347         return 1;
 348 }
 349
 350 static int tcf_csum_ipv4(struct sk_buff *skb, u32 update_flags)
 351 {
 352         const struct iphdr *iph;
 353         int ntkoff;
 354
 355         ntkoff = skb_network_offset(skb);
 356
 357         if (!pskb_may_pull(skb, sizeof(*iph) + ntkoff))
 358                 goto fail;
 359
 360         iph = ip_hdr(skb);
 361
 362         switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
 363         case IPPROTO_ICMP:
 364                 if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP)
 365                         if (!tcf_csum_ipv4_icmp(skb, iph->ihl * 4,
 366                                                 ntohs(iph->tot_len)))
 367                                 goto fail;
 368                 break;
 369         case IPPROTO_IGMP:
 370                 if (update_flags & TCA_CSUM_UPDATE_FLAG_IGMP)
 371                         if (!tcf_csum_ipv4_igmp(skb, iph->ihl * 4,
 372                                                 ntohs(iph->tot_len)))
 373                                 goto fail;
 374                 break;
 375         case IPPROTO_TCP:
 376                 if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP)
 377                         if (!tcf_csum_ipv4_tcp(skb, iph->ihl * 4,
 378                                                ntohs(iph->tot_len)))
 379                                 goto fail;
 380                 break;
 381         case IPPROTO_UDP:
 382                 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP)
 383                         if (!tcf_csum_ipv4_udp(skb, iph->ihl * 4,
 384                                                ntohs(iph->tot_len), 0))
 385                                 goto fail;
 386                 break;
 387         case IPPROTO_UDPLITE:
 388                 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE)
 389                         if (!tcf_csum_ipv4_udp(skb, iph->ihl * 4,
 390                                                ntohs(iph->tot_len), 1))
 391                                 goto fail;
 392                 break;
 393         case IPPROTO_SCTP:
 394                 if ((update_flags & TCA_CSUM_UPDATE_FLAG_SCTP) &&
 395                     !tcf_csum_sctp(skb, iph->ihl * 4, ntohs(iph->tot_len)))
 396                         goto fail;
 397                 break;
 398         }
 399
 400         if (update_flags & TCA_CSUM_UPDATE_FLAG_IPV4HDR) {
 401                 if (skb_try_make_writable(skb, sizeof(*iph) + ntkoff))
 402                         goto fail;
 403
 404                 ip_send_check(ip_hdr(skb));
 405         }
 406
 407         return 1;
 408
 409 fail:
 410         return 0;
 411 }
 412
 413 static int tcf_csum_ipv6_hopopts(struct ipv6_opt_hdr *ip6xh, unsigned int ixhl,
 414                                  unsigned int *pl)
 415 {
 416         int off, len, optlen;
 417         unsigned char *xh = (void *)ip6xh;
 418
 419         off = sizeof(*ip6xh);
 420         len = ixhl - off;
 421
 422         while (len > 1) {
 423                 switch (xh[off]) {
 424                 case IPV6_TLV_PAD1:
 425                         optlen = 1;
 426                         break;
 427                 case IPV6_TLV_JUMBO:
 428                         optlen = xh[off + 1] + 2;
 429                         if (optlen != 6 || len < 6 || (off & 3) != 2)
 430                                 /* wrong jumbo option length/alignment */
 431                                 return 0;
 432                         *pl = ntohl(*(__be32 *)(xh + off + 2));
 433                         goto done;
 434                 default:
 435                         optlen = xh[off + 1] + 2;
 436                         if (optlen > len)
 437                                 /* ignore obscure options */
 438                                 goto done;
 439                         break;
 440                 }
 441                 off += optlen;
 442                 len -= optlen;
 443         }
 444
 445 done:
 446         return 1;
 447 }
 448
 449 static int tcf_csum_ipv6(struct sk_buff *skb, u32 update_flags)
 450 {
 451         struct ipv6hdr *ip6h;
 452         struct ipv6_opt_hdr *ip6xh;
 453         unsigned int hl, ixhl;
 454         unsigned int pl;
 455         int ntkoff;
 456         u8 nexthdr;
 457
 458         ntkoff = skb_network_offset(skb);
 459
 460         hl = sizeof(*ip6h);
 461
 462         if (!pskb_may_pull(skb, hl + ntkoff))
 463                 goto fail;
 464
 465         ip6h = ipv6_hdr(skb);
 466
 467         pl = ntohs(ip6h->payload_len);
 468         nexthdr = ip6h->nexthdr;
 469
 470         do {
 471                 switch (nexthdr) {
 472                 case NEXTHDR_FRAGMENT:
 473                         goto ignore_skb;
 474                 case NEXTHDR_ROUTING:
 475                 case NEXTHDR_HOP:
 476                 case NEXTHDR_DEST:
 477                         if (!pskb_may_pull(skb, hl + sizeof(*ip6xh) + ntkoff))
 478                                 goto fail;
 479                         ip6xh = (void *)(skb_network_header(skb) + hl);
 480                         ixhl = ipv6_optlen(ip6xh);
 481                         if (!pskb_may_pull(skb, hl + ixhl + ntkoff))
 482                                 goto fail;
 483                         ip6xh = (void *)(skb_network_header(skb) + hl);
 484                         if ((nexthdr == NEXTHDR_HOP) &&
 485                             !(tcf_csum_ipv6_hopopts(ip6xh, ixhl, &pl)))
 486                                 goto fail;
 487                         nexthdr = ip6xh->nexthdr;
 488                         hl += ixhl;
 489                         break;
 490                 case IPPROTO_ICMPV6:
 491                         if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP)
 492                                 if (!tcf_csum_ipv6_icmp(skb,
 493                                                         hl, pl + sizeof(*ip6h)))
 494                                         goto fail;
 495                         goto done;
 496                 case IPPROTO_TCP:
 497                         if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP)
 498                                 if (!tcf_csum_ipv6_tcp(skb,
 499                                                        hl, pl + sizeof(*ip6h)))
 500                                         goto fail;
 501                         goto done;
 502                 case IPPROTO_UDP:
 503                         if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP)
 504                                 if (!tcf_csum_ipv6_udp(skb, hl,
 505                                                        pl + sizeof(*ip6h), 0))
 506                                         goto fail;
 507                         goto done;
 508                 case IPPROTO_UDPLITE:
 509                         if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE)
 510                                 if (!tcf_csum_ipv6_udp(skb, hl,
 511                                                        pl + sizeof(*ip6h), 1))
 512                                         goto fail;
 513                         goto done;
 514                 case IPPROTO_SCTP:
 515                         if ((update_flags & TCA_CSUM_UPDATE_FLAG_SCTP) &&
 516                             !tcf_csum_sctp(skb, hl, pl + sizeof(*ip6h)))
 517                                 goto fail;
 518                         goto done;
 519                 default:
 520                         goto ignore_skb;
 521                 }
 522         } while (pskb_may_pull(skb, hl + 1 + ntkoff));
 523
 524 done:
 525 ignore_skb:
 526         return 1;
 527
 528 fail:
 529         return 0;
 530 }
 531
 532 static int tcf_csum(struct sk_buff *skb, const struct tc_action *a,
 533                     struct tcf_result *res)
 534 {
 535         struct tcf_csum *p = to_tcf_csum(a);
 536         int action;
 537         u32 update_flags;
 538
 539         spin_lock(&p->tcf_lock);
 540         tcf_lastuse_update(&p->tcf_tm);
 541         bstats_update(&p->tcf_bstats, skb);
 542         action = p->tcf_action;
 543         update_flags = p->update_flags;
 544         spin_unlock(&p->tcf_lock);
 545
 546         if (unlikely(action == TC_ACT_SHOT))
 547                 goto drop;
 548
 549         switch (tc_skb_protocol(skb)) {
 550         case cpu_to_be16(ETH_P_IP):
 551                 if (!tcf_csum_ipv4(skb, update_flags))
 552                         goto drop;
 553                 break;
 554         case cpu_to_be16(ETH_P_IPV6):
 555                 if (!tcf_csum_ipv6(skb, update_flags))
 556                         goto drop;
 557                 break;
 558         }
 559
 560         return action;
 561
 562 drop:
 563         spin_lock(&p->tcf_lock);
 564         p->tcf_qstats.drops++;
 565         spin_unlock(&p->tcf_lock);
 566         return TC_ACT_SHOT;
 567 }
 568
 569 static int tcf_csum_dump(struct sk_buff *skb, struct tc_action *a, int bind,
 570                          int ref)
 571 {
 572         unsigned char *b = skb_tail_pointer(skb);
 573         struct tcf_csum *p = to_tcf_csum(a);
 574         struct tc_csum opt = {
 575                 .update_flags = p->update_flags,
 576                 .index   = p->tcf_index,
 577                 .action  = p->tcf_action,
 578                 .refcnt  = p->tcf_refcnt - ref,
 579                 .bindcnt = p->tcf_bindcnt - bind,
 580         };
 581         struct tcf_t t;
 582
 583         if (nla_put(skb, TCA_CSUM_PARMS, sizeof(opt), &opt))
 584                 goto nla_put_failure;
 585
 586         tcf_tm_dump(&t, &p->tcf_tm);
 587         if (nla_put_64bit(skb, TCA_CSUM_TM, sizeof(t), &t, TCA_CSUM_PAD))
 588                 goto nla_put_failure;
 589
 590         return skb->len;
 591
 592 nla_put_failure:
 593         nlmsg_trim(skb, b);
 594         return -1;
 595 }
 596
 597 static int tcf_csum_walker(struct net *net, struct sk_buff *skb,
 598                            struct netlink_callback *cb, int type,
 599                            const struct tc_action_ops *ops)
 600 {
 601         struct tc_action_net *tn = net_generic(net, csum_net_id);
 602
 603         return tcf_generic_walker(tn, skb, cb, type, ops);
 604 }
 605
 606 static int tcf_csum_search(struct net *net, struct tc_action **a, u32 index)
 607 {
 608         struct tc_action_net *tn = net_generic(net, csum_net_id);
 609
 610         return tcf_idr_search(tn, a, index);
 611 }
 612
 613 static struct tc_action_ops act_csum_ops = {
 614         .kind           = "csum",
 615         .type           = TCA_ACT_CSUM,
 616         .owner          = THIS_MODULE,
 617         .act            = tcf_csum,
 618         .dump           = tcf_csum_dump,
 619         .init           = tcf_csum_init,
 620         .walk           = tcf_csum_walker,
 621         .lookup         = tcf_csum_search,
 622         .size           = sizeof(struct tcf_csum),
 623 };
 624
 625 static __net_init int csum_init_net(struct net *net)
 626 {
 627         struct tc_action_net *tn = net_generic(net, csum_net_id);
 628
 629         return tc_action_net_init(tn, &act_csum_ops);
 630 }
 631
 632 static void __net_exit csum_exit_net(struct net *net)
 633 {
 634         struct tc_action_net *tn = net_generic(net, csum_net_id);
 635
 636         tc_action_net_exit(tn);
 637 }
 638
 639 static struct pernet_operations csum_net_ops = {
 640         .init = csum_init_net,
 641         .exit = csum_exit_net,
 642         .id   = &csum_net_id,
 643         .size = sizeof(struct tc_action_net),
 644 };
 645
 646 MODULE_DESCRIPTION("Checksum updating actions");
 647 MODULE_LICENSE("GPL");
 648
 649 static int __init csum_init_module(void)
 650 {
 651         return tcf_register_action(&act_csum_ops, &csum_net_ops);
 652 }
 653
 654 static void __exit csum_cleanup_module(void)
 655 {
 656         tcf_unregister_action(&act_csum_ops, &csum_net_ops);
 657 }
 658
 659 module_init(csum_init_module);
 660 module_exit(csum_cleanup_module);