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