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
  34 #include <net/act_api.h>
  35
  36 #include <linux/tc_act/tc_csum.h>
  37 #include <net/tc_act/tc_csum.h>
  38
  39 #define CSUM_TAB_MASK 15
  40 static struct tcf_common *tcf_csum_ht[CSUM_TAB_MASK + 1];
  41 static u32 csum_idx_gen;
  42 static DEFINE_RWLOCK(csum_lock);
  43
  44 static struct tcf_hashinfo csum_hash_info = {
  45         .htab   = tcf_csum_ht,
  46         .hmask  = CSUM_TAB_MASK,
  47         .lock   = &csum_lock,
  48 };
  49
  50 static const struct nla_policy csum_policy[TCA_CSUM_MAX + 1] = {
  51         [TCA_CSUM_PARMS] = { .len = sizeof(struct tc_csum), },
  52 };
  53
  54 static int tcf_csum_init(struct nlattr *nla, struct nlattr *est,
  55                          struct tc_action *a, int ovr, int bind)
  56 {
  57         struct nlattr *tb[TCA_CSUM_MAX + 1];
  58         struct tc_csum *parm;
  59         struct tcf_common *pc;
  60         struct tcf_csum *p;
  61         int ret = 0, err;
  62
  63         if (nla == NULL)
  64                 return -EINVAL;
  65
  66         err = nla_parse_nested(tb, TCA_CSUM_MAX, nla, csum_policy);
  67         if (err < 0)
  68                 return err;
  69
  70         if (tb[TCA_CSUM_PARMS] == NULL)
  71                 return -EINVAL;
  72         parm = nla_data(tb[TCA_CSUM_PARMS]);
  73
  74         pc = tcf_hash_check(parm->index, a, bind, &csum_hash_info);
  75         if (!pc) {
  76                 pc = tcf_hash_create(parm->index, est, a, sizeof(*p), bind,
  77                                      &csum_idx_gen, &csum_hash_info);
  78                 if (IS_ERR(pc))
  79                         return PTR_ERR(pc);
  80                 p = to_tcf_csum(pc);
  81                 ret = ACT_P_CREATED;
  82         } else {
  83                 p = to_tcf_csum(pc);
  84                 if (!ovr) {
  85                         tcf_hash_release(pc, bind, &csum_hash_info);
  86                         return -EEXIST;
  87                 }
  88         }
  89
  90         spin_lock_bh(&p->tcf_lock);
  91         p->tcf_action = parm->action;
  92         p->update_flags = parm->update_flags;
  93         spin_unlock_bh(&p->tcf_lock);
  94
  95         if (ret == ACT_P_CREATED)
  96                 tcf_hash_insert(pc, &csum_hash_info);
  97
  98         return ret;
  99 }
 100
 101 static int tcf_csum_cleanup(struct tc_action *a, int bind)
 102 {
 103         struct tcf_csum *p = a->priv;
 104         return tcf_hash_release(&p->common, bind, &csum_hash_info);
 105 }
 106
 107 /**
 108  * tcf_csum_skb_nextlayer - Get next layer pointer
 109  * @skb: sk_buff to use
 110  * @ihl: previous summed headers length
 111  * @ipl: complete packet length
 112  * @jhl: next header length
 113  *
 114  * Check the expected next layer availability in the specified sk_buff.
 115  * Return the next layer pointer if pass, NULL otherwise.
 116  */
 117 static void *tcf_csum_skb_nextlayer(struct sk_buff *skb,
 118                                     unsigned int ihl, unsigned int ipl,
 119                                     unsigned int jhl)
 120 {
 121         int ntkoff = skb_network_offset(skb);
 122         int hl = ihl + jhl;
 123
 124         if (!pskb_may_pull(skb, ipl + ntkoff) || (ipl < hl) ||
 125             (skb_cloned(skb) &&
 126              !skb_clone_writable(skb, hl + ntkoff) &&
 127              pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
 128                 return NULL;
 129         else
 130                 return (void *)(skb_network_header(skb) + ihl);
 131 }
 132
 133 static int tcf_csum_ipv4_icmp(struct sk_buff *skb,
 134                               unsigned int ihl, unsigned int ipl)
 135 {
 136         struct icmphdr *icmph;
 137
 138         icmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmph));
 139         if (icmph == NULL)
 140                 return 0;
 141
 142         icmph->checksum = 0;
 143         skb->csum = csum_partial(icmph, ipl - ihl, 0);
 144         icmph->checksum = csum_fold(skb->csum);
 145
 146         skb->ip_summed = CHECKSUM_NONE;
 147
 148         return 1;
 149 }
 150
 151 static int tcf_csum_ipv4_igmp(struct sk_buff *skb,
 152                               unsigned int ihl, unsigned int ipl)
 153 {
 154         struct igmphdr *igmph;
 155
 156         igmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*igmph));
 157         if (igmph == NULL)
 158                 return 0;
 159
 160         igmph->csum = 0;
 161         skb->csum = csum_partial(igmph, ipl - ihl, 0);
 162         igmph->csum = csum_fold(skb->csum);
 163
 164         skb->ip_summed = CHECKSUM_NONE;
 165
 166         return 1;
 167 }
 168
 169 static int tcf_csum_ipv6_icmp(struct sk_buff *skb, struct ipv6hdr *ip6h,
 170                               unsigned int ihl, unsigned int ipl)
 171 {
 172         struct icmp6hdr *icmp6h;
 173
 174         icmp6h = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmp6h));
 175         if (icmp6h == NULL)
 176                 return 0;
 177
 178         icmp6h->icmp6_cksum = 0;
 179         skb->csum = csum_partial(icmp6h, ipl - ihl, 0);
 180         icmp6h->icmp6_cksum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 181                                               ipl - ihl, IPPROTO_ICMPV6,
 182                                               skb->csum);
 183
 184         skb->ip_summed = CHECKSUM_NONE;
 185
 186         return 1;
 187 }
 188
 189 static int tcf_csum_ipv4_tcp(struct sk_buff *skb, struct iphdr *iph,
 190                              unsigned int ihl, unsigned int ipl)
 191 {
 192         struct tcphdr *tcph;
 193
 194         tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph));
 195         if (tcph == NULL)
 196                 return 0;
 197
 198         tcph->check = 0;
 199         skb->csum = csum_partial(tcph, ipl - ihl, 0);
 200         tcph->check = tcp_v4_check(ipl - ihl,
 201                                    iph->saddr, iph->daddr, skb->csum);
 202
 203         skb->ip_summed = CHECKSUM_NONE;
 204
 205         return 1;
 206 }
 207
 208 static int tcf_csum_ipv6_tcp(struct sk_buff *skb, struct ipv6hdr *ip6h,
 209                              unsigned int ihl, unsigned int ipl)
 210 {
 211         struct tcphdr *tcph;
 212
 213         tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph));
 214         if (tcph == NULL)
 215                 return 0;
 216
 217         tcph->check = 0;
 218         skb->csum = csum_partial(tcph, ipl - ihl, 0);
 219         tcph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 220                                       ipl - ihl, IPPROTO_TCP,
 221                                       skb->csum);
 222
 223         skb->ip_summed = CHECKSUM_NONE;
 224
 225         return 1;
 226 }
 227
 228 static int tcf_csum_ipv4_udp(struct sk_buff *skb, struct iphdr *iph,
 229                              unsigned int ihl, unsigned int ipl, int udplite)
 230 {
 231         struct udphdr *udph;
 232         u16 ul;
 233
 234         /*
 235          * Support both UDP and UDPLITE checksum algorithms, Don't use
 236          * udph->len to get the real length without any protocol check,
 237          * UDPLITE uses udph->len for another thing,
 238          * Use iph->tot_len, or just ipl.
 239          */
 240
 241         udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph));
 242         if (udph == NULL)
 243                 return 0;
 244
 245         ul = ntohs(udph->len);
 246
 247         if (udplite || udph->check) {
 248
 249                 udph->check = 0;
 250
 251                 if (udplite) {
 252                         if (ul == 0)
 253                                 skb->csum = csum_partial(udph, ipl - ihl, 0);
 254                         else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl))
 255                                 skb->csum = csum_partial(udph, ul, 0);
 256                         else
 257                                 goto ignore_obscure_skb;
 258                 } else {
 259                         if (ul != ipl - ihl)
 260                                 goto ignore_obscure_skb;
 261
 262                         skb->csum = csum_partial(udph, ul, 0);
 263                 }
 264
 265                 udph->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
 266                                                 ul, iph->protocol,
 267                                                 skb->csum);
 268
 269                 if (!udph->check)
 270                         udph->check = CSUM_MANGLED_0;
 271         }
 272
 273         skb->ip_summed = CHECKSUM_NONE;
 274
 275 ignore_obscure_skb:
 276         return 1;
 277 }
 278
 279 static int tcf_csum_ipv6_udp(struct sk_buff *skb, struct ipv6hdr *ip6h,
 280                              unsigned int ihl, unsigned int ipl, int udplite)
 281 {
 282         struct udphdr *udph;
 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         ul = ntohs(udph->len);
 297
 298         udph->check = 0;
 299
 300         if (udplite) {
 301                 if (ul == 0)
 302                         skb->csum = csum_partial(udph, ipl - ihl, 0);
 303
 304                 else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl))
 305                         skb->csum = csum_partial(udph, ul, 0);
 306
 307                 else
 308                         goto ignore_obscure_skb;
 309         } else {
 310                 if (ul != ipl - ihl)
 311                         goto ignore_obscure_skb;
 312
 313                 skb->csum = csum_partial(udph, ul, 0);
 314         }
 315
 316         udph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, ul,
 317                                       udplite ? IPPROTO_UDPLITE : IPPROTO_UDP,
 318                                       skb->csum);
 319
 320         if (!udph->check)
 321                 udph->check = CSUM_MANGLED_0;
 322
 323         skb->ip_summed = CHECKSUM_NONE;
 324
 325 ignore_obscure_skb:
 326         return 1;
 327 }
 328
 329 static int tcf_csum_ipv4(struct sk_buff *skb, u32 update_flags)
 330 {
 331         struct iphdr *iph;
 332         int ntkoff;
 333
 334         ntkoff = skb_network_offset(skb);
 335
 336         if (!pskb_may_pull(skb, sizeof(*iph) + ntkoff))
 337                 goto fail;
 338
 339         iph = ip_hdr(skb);
 340
 341         switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
 342         case IPPROTO_ICMP:
 343                 if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP)
 344                         if (!tcf_csum_ipv4_icmp(skb, iph->ihl * 4,
 345                                                 ntohs(iph->tot_len)))
 346                                 goto fail;
 347                 break;
 348         case IPPROTO_IGMP:
 349                 if (update_flags & TCA_CSUM_UPDATE_FLAG_IGMP)
 350                         if (!tcf_csum_ipv4_igmp(skb, iph->ihl * 4,
 351                                                 ntohs(iph->tot_len)))
 352                                 goto fail;
 353                 break;
 354         case IPPROTO_TCP:
 355                 if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP)
 356                         if (!tcf_csum_ipv4_tcp(skb, iph, iph->ihl * 4,
 357                                                ntohs(iph->tot_len)))
 358                                 goto fail;
 359                 break;
 360         case IPPROTO_UDP:
 361                 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP)
 362                         if (!tcf_csum_ipv4_udp(skb, iph, iph->ihl * 4,
 363                                                ntohs(iph->tot_len), 0))
 364                                 goto fail;
 365                 break;
 366         case IPPROTO_UDPLITE:
 367                 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE)
 368                         if (!tcf_csum_ipv4_udp(skb, iph, iph->ihl * 4,
 369                                                ntohs(iph->tot_len), 1))
 370                                 goto fail;
 371                 break;
 372         }
 373
 374         if (update_flags & TCA_CSUM_UPDATE_FLAG_IPV4HDR) {
 375                 if (skb_cloned(skb) &&
 376                     !skb_clone_writable(skb, sizeof(*iph) + ntkoff) &&
 377                     pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 378                         goto fail;
 379
 380                 ip_send_check(iph);
 381         }
 382
 383         return 1;
 384
 385 fail:
 386         return 0;
 387 }
 388
 389 static int tcf_csum_ipv6_hopopts(struct ipv6_opt_hdr *ip6xh,
 390                                  unsigned int ixhl, unsigned int *pl)
 391 {
 392         int off, len, optlen;
 393         unsigned char *xh = (void *)ip6xh;
 394
 395         off = sizeof(*ip6xh);
 396         len = ixhl - off;
 397
 398         while (len > 1) {
 399                 switch (xh[off]) {
 400                 case IPV6_TLV_PAD0:
 401                         optlen = 1;
 402                         break;
 403                 case IPV6_TLV_JUMBO:
 404                         optlen = xh[off + 1] + 2;
 405                         if (optlen != 6 || len < 6 || (off & 3) != 2)
 406                                 /* wrong jumbo option length/alignment */
 407                                 return 0;
 408                         *pl = ntohl(*(__be32 *)(xh + off + 2));
 409                         goto done;
 410                 default:
 411                         optlen = xh[off + 1] + 2;
 412                         if (optlen > len)
 413                                 /* ignore obscure options */
 414                                 goto done;
 415                         break;
 416                 }
 417                 off += optlen;
 418                 len -= optlen;
 419         }
 420
 421 done:
 422         return 1;
 423 }
 424
 425 static int tcf_csum_ipv6(struct sk_buff *skb, u32 update_flags)
 426 {
 427         struct ipv6hdr *ip6h;
 428         struct ipv6_opt_hdr *ip6xh;
 429         unsigned int hl, ixhl;
 430         unsigned int pl;
 431         int ntkoff;
 432         u8 nexthdr;
 433
 434         ntkoff = skb_network_offset(skb);
 435
 436         hl = sizeof(*ip6h);
 437
 438         if (!pskb_may_pull(skb, hl + ntkoff))
 439                 goto fail;
 440
 441         ip6h = ipv6_hdr(skb);
 442
 443         pl = ntohs(ip6h->payload_len);
 444         nexthdr = ip6h->nexthdr;
 445
 446         do {
 447                 switch (nexthdr) {
 448                 case NEXTHDR_FRAGMENT:
 449                         goto ignore_skb;
 450                 case NEXTHDR_ROUTING:
 451                 case NEXTHDR_HOP:
 452                 case NEXTHDR_DEST:
 453                         if (!pskb_may_pull(skb, hl + sizeof(*ip6xh) + ntkoff))
 454                                 goto fail;
 455                         ip6xh = (void *)(skb_network_header(skb) + hl);
 456                         ixhl = ipv6_optlen(ip6xh);
 457                         if (!pskb_may_pull(skb, hl + ixhl + ntkoff))
 458                                 goto fail;
 459                         if ((nexthdr == NEXTHDR_HOP) &&
 460                             !(tcf_csum_ipv6_hopopts(ip6xh, ixhl, &pl)))
 461                                 goto fail;
 462                         nexthdr = ip6xh->nexthdr;
 463                         hl += ixhl;
 464                         break;
 465                 case IPPROTO_ICMPV6:
 466                         if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP)
 467                                 if (!tcf_csum_ipv6_icmp(skb, ip6h,
 468                                                         hl, pl + sizeof(*ip6h)))
 469                                         goto fail;
 470                         goto done;
 471                 case IPPROTO_TCP:
 472                         if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP)
 473                                 if (!tcf_csum_ipv6_tcp(skb, ip6h,
 474                                                        hl, pl + sizeof(*ip6h)))
 475                                         goto fail;
 476                         goto done;
 477                 case IPPROTO_UDP:
 478                         if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP)
 479                                 if (!tcf_csum_ipv6_udp(skb, ip6h, hl,
 480                                                        pl + sizeof(*ip6h), 0))
 481                                         goto fail;
 482                         goto done;
 483                 case IPPROTO_UDPLITE:
 484                         if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE)
 485                                 if (!tcf_csum_ipv6_udp(skb, ip6h, hl,
 486                                                        pl + sizeof(*ip6h), 1))
 487                                         goto fail;
 488                         goto done;
 489                 default:
 490                         goto ignore_skb;
 491                 }
 492         } while (pskb_may_pull(skb, hl + 1 + ntkoff));
 493
 494 done:
 495 ignore_skb:
 496         return 1;
 497
 498 fail:
 499         return 0;
 500 }
 501
 502 static int tcf_csum(struct sk_buff *skb,
 503                     const struct tc_action *a, struct tcf_result *res)
 504 {
 505         struct tcf_csum *p = a->priv;
 506         int action;
 507         u32 update_flags;
 508
 509         spin_lock(&p->tcf_lock);
 510         p->tcf_tm.lastuse = jiffies;
 511         bstats_update(&p->tcf_bstats, skb);
 512         action = p->tcf_action;
 513         update_flags = p->update_flags;
 514         spin_unlock(&p->tcf_lock);
 515
 516         if (unlikely(action == TC_ACT_SHOT))
 517                 goto drop;
 518
 519         switch (skb->protocol) {
 520         case cpu_to_be16(ETH_P_IP):
 521                 if (!tcf_csum_ipv4(skb, update_flags))
 522                         goto drop;
 523                 break;
 524         case cpu_to_be16(ETH_P_IPV6):
 525                 if (!tcf_csum_ipv6(skb, update_flags))
 526                         goto drop;
 527                 break;
 528         }
 529
 530         return action;
 531
 532 drop:
 533         spin_lock(&p->tcf_lock);
 534         p->tcf_qstats.drops++;
 535         spin_unlock(&p->tcf_lock);
 536         return TC_ACT_SHOT;
 537 }
 538
 539 static int tcf_csum_dump(struct sk_buff *skb,
 540                          struct tc_action *a, int bind, int ref)
 541 {
 542         unsigned char *b = skb_tail_pointer(skb);
 543         struct tcf_csum *p = a->priv;
 544         struct tc_csum opt = {
 545                 .update_flags = p->update_flags,
 546                 .index   = p->tcf_index,
 547                 .action  = p->tcf_action,
 548                 .refcnt  = p->tcf_refcnt - ref,
 549                 .bindcnt = p->tcf_bindcnt - bind,
 550         };
 551         struct tcf_t t;
 552
 553         NLA_PUT(skb, TCA_CSUM_PARMS, sizeof(opt), &opt);
 554         t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
 555         t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
 556         t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
 557         NLA_PUT(skb, TCA_CSUM_TM, sizeof(t), &t);
 558
 559         return skb->len;
 560
 561 nla_put_failure:
 562         nlmsg_trim(skb, b);
 563         return -1;
 564 }
 565
 566 static struct tc_action_ops act_csum_ops = {
 567         .kind           = "csum",
 568         .hinfo          = &csum_hash_info,
 569         .type           = TCA_ACT_CSUM,
 570         .capab          = TCA_CAP_NONE,
 571         .owner          = THIS_MODULE,
 572         .act            = tcf_csum,
 573         .dump           = tcf_csum_dump,
 574         .cleanup        = tcf_csum_cleanup,
 575         .lookup         = tcf_hash_search,
 576         .init           = tcf_csum_init,
 577         .walk           = tcf_generic_walker
 578 };
 579
 580 MODULE_DESCRIPTION("Checksum updating actions");
 581 MODULE_LICENSE("GPL");
 582
 583 static int __init csum_init_module(void)
 584 {
 585         return tcf_register_action(&act_csum_ops);
 586 }
 587
 588 static void __exit csum_cleanup_module(void)
 589 {
 590         tcf_unregister_action(&act_csum_ops);
 591 }
 592
 593 module_init(csum_init_module);
 594 module_exit(csum_cleanup_module);