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, &csum_idx_gen, &csum_hash_info);
  77                 if (IS_ERR(pc))
  78                         return PTR_ERR(pc);
  79                 p = to_tcf_csum(pc);
  80                 ret = ACT_P_CREATED;
  81         } else {
  82                 p = to_tcf_csum(pc);
  83                 if (!ovr) {
  84                         tcf_hash_release(pc, bind, &csum_hash_info);
  85                         return -EEXIST;
  86                 }
  87         }
  88
  89         spin_lock_bh(&p->tcf_lock);
  90         p->tcf_action = parm->action;
  91         p->update_flags = parm->update_flags;
  92         spin_unlock_bh(&p->tcf_lock);
  93
  94         if (ret == ACT_P_CREATED)
  95                 tcf_hash_insert(pc, &csum_hash_info);
  96
  97         return ret;
  98 }
  99
 100 static int tcf_csum_cleanup(struct tc_action *a, int bind)
 101 {
 102         struct tcf_csum *p = a->priv;
 103         return tcf_hash_release(&p->common, bind, &csum_hash_info);
 104 }
 105
 106 /**
 107  * tcf_csum_skb_nextlayer - Get next layer pointer
 108  * @skb: sk_buff to use
 109  * @ihl: previous summed headers length
 110  * @ipl: complete packet length
 111  * @jhl: next header length
 112  *
 113  * Check the expected next layer availability in the specified sk_buff.
 114  * Return the next layer pointer if pass, NULL otherwise.
 115  */
 116 static void *tcf_csum_skb_nextlayer(struct sk_buff *skb,
 117                                     unsigned int ihl, unsigned int ipl,
 118                                     unsigned int jhl)
 119 {
 120         int ntkoff = skb_network_offset(skb);
 121         int hl = ihl + jhl;
 122
 123         if (!pskb_may_pull(skb, ipl + ntkoff) || (ipl < hl) ||
 124             (skb_cloned(skb) &&
 125              !skb_clone_writable(skb, hl + ntkoff) &&
 126              pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
 127                 return NULL;
 128         else
 129                 return (void *)(skb_network_header(skb) + ihl);
 130 }
 131
 132 static int tcf_csum_ipv4_icmp(struct sk_buff *skb,
 133                               unsigned int ihl, unsigned int ipl)
 134 {
 135         struct icmphdr *icmph;
 136
 137         icmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmph));
 138         if (icmph == NULL)
 139                 return 0;
 140
 141         icmph->checksum = 0;
 142         skb->csum = csum_partial(icmph, ipl - ihl, 0);
 143         icmph->checksum = csum_fold(skb->csum);
 144
 145         skb->ip_summed = CHECKSUM_NONE;
 146
 147         return 1;
 148 }
 149
 150 static int tcf_csum_ipv4_igmp(struct sk_buff *skb,
 151                               unsigned int ihl, unsigned int ipl)
 152 {
 153         struct igmphdr *igmph;
 154
 155         igmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*igmph));
 156         if (igmph == NULL)
 157                 return 0;
 158
 159         igmph->csum = 0;
 160         skb->csum = csum_partial(igmph, ipl - ihl, 0);
 161         igmph->csum = csum_fold(skb->csum);
 162
 163         skb->ip_summed = CHECKSUM_NONE;
 164
 165         return 1;
 166 }
 167
 168 static int tcf_csum_ipv6_icmp(struct sk_buff *skb, struct ipv6hdr *ip6h,
 169                               unsigned int ihl, unsigned int ipl)
 170 {
 171         struct icmp6hdr *icmp6h;
 172
 173         icmp6h = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmp6h));
 174         if (icmp6h == NULL)
 175                 return 0;
 176
 177         icmp6h->icmp6_cksum = 0;
 178         skb->csum = csum_partial(icmp6h, ipl - ihl, 0);
 179         icmp6h->icmp6_cksum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 180                                               ipl - ihl, IPPROTO_ICMPV6,
 181                                               skb->csum);
 182
 183         skb->ip_summed = CHECKSUM_NONE;
 184
 185         return 1;
 186 }
 187
 188 static int tcf_csum_ipv4_tcp(struct sk_buff *skb, struct iphdr *iph,
 189                              unsigned int ihl, unsigned int ipl)
 190 {
 191         struct tcphdr *tcph;
 192
 193         tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph));
 194         if (tcph == NULL)
 195                 return 0;
 196
 197         tcph->check = 0;
 198         skb->csum = csum_partial(tcph, ipl - ihl, 0);
 199         tcph->check = tcp_v4_check(ipl - ihl,
 200                                    iph->saddr, iph->daddr, skb->csum);
 201
 202         skb->ip_summed = CHECKSUM_NONE;
 203
 204         return 1;
 205 }
 206
 207 static int tcf_csum_ipv6_tcp(struct sk_buff *skb, struct ipv6hdr *ip6h,
 208                              unsigned int ihl, unsigned int ipl)
 209 {
 210         struct tcphdr *tcph;
 211
 212         tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph));
 213         if (tcph == NULL)
 214                 return 0;
 215
 216         tcph->check = 0;
 217         skb->csum = csum_partial(tcph, ipl - ihl, 0);
 218         tcph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 219                                       ipl - ihl, IPPROTO_TCP,
 220                                       skb->csum);
 221
 222         skb->ip_summed = CHECKSUM_NONE;
 223
 224         return 1;
 225 }
 226
 227 static int tcf_csum_ipv4_udp(struct sk_buff *skb, struct iphdr *iph,
 228                              unsigned int ihl, unsigned int ipl, int udplite)
 229 {
 230         struct udphdr *udph;
 231         u16 ul;
 232
 233         /* Support both UDP and UDPLITE checksum algorithms,
 234          * Don't use 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         ul = ntohs(udph->len);
 244
 245         if (udplite || udph->check) {
 246
 247                 udph->check = 0;
 248
 249                 if (udplite) {
 250                         if (ul == 0)
 251                                 skb->csum = csum_partial(udph, ipl - ihl, 0);
 252
 253                         else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl))
 254                                 skb->csum = csum_partial(udph, ul, 0);
 255
 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         /* Support both UDP and UDPLITE checksum algorithms,
 286          * Don't use udph->len to get the real length without any protocol check,
 287          * UDPLITE uses udph->len for another thing,
 288          * Use ip6h->payload_len + sizeof(*ip6h) ... , or just ipl.
 289          */
 290
 291         udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph));
 292         if (udph == NULL)
 293                 return 0;
 294
 295         ul = ntohs(udph->len);
 296
 297         udph->check = 0;
 298
 299         if (udplite) {
 300                 if (ul == 0)
 301                         skb->csum = csum_partial(udph, ipl - ihl, 0);
 302
 303                 else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl))
 304                         skb->csum = csum_partial(udph, ul, 0);
 305
 306                 else
 307                         goto ignore_obscure_skb;
 308         } else {
 309                 if (ul != ipl - ihl)
 310                         goto ignore_obscure_skb;
 311
 312                 skb->csum = csum_partial(udph, ul, 0);
 313         }
 314
 315         udph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, ul,
 316                                       udplite ? IPPROTO_UDPLITE : IPPROTO_UDP,
 317                                       skb->csum);
 318
 319         if (!udph->check)
 320                 udph->check = CSUM_MANGLED_0;
 321
 322         skb->ip_summed = CHECKSUM_NONE;
 323
 324 ignore_obscure_skb:
 325         return 1;
 326 }
 327
 328 static int tcf_csum_ipv4(struct sk_buff *skb, u32 update_flags)
 329 {
 330         struct iphdr *iph;
 331         int ntkoff;
 332
 333         ntkoff = skb_network_offset(skb);
 334
 335         if (!pskb_may_pull(skb, sizeof(*iph) + ntkoff))
 336                 goto fail;
 337
 338         iph = ip_hdr(skb);
 339
 340         switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
 341         case IPPROTO_ICMP:
 342                 if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP)
 343                         if (!tcf_csum_ipv4_icmp(skb,
 344                                                 iph->ihl * 4, ntohs(iph->tot_len)))
 345                                 goto fail;
 346                 break;
 347         case IPPROTO_IGMP:
 348                 if (update_flags & TCA_CSUM_UPDATE_FLAG_IGMP)
 349                         if (!tcf_csum_ipv4_igmp(skb,
 350                                                 iph->ihl * 4, ntohs(iph->tot_len)))
 351                                 goto fail;
 352                 break;
 353         case IPPROTO_TCP:
 354                 if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP)
 355                         if (!tcf_csum_ipv4_tcp(skb, iph,
 356                                                iph->ihl * 4, ntohs(iph->tot_len)))
 357                                 goto fail;
 358                 break;
 359         case IPPROTO_UDP:
 360                 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP)
 361                         if (!tcf_csum_ipv4_udp(skb, iph,
 362                                                iph->ihl * 4, ntohs(iph->tot_len), 0))
 363                                 goto fail;
 364                 break;
 365         case IPPROTO_UDPLITE:
 366                 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE)
 367                         if (!tcf_csum_ipv4_udp(skb, iph,
 368                                                iph->ihl * 4, ntohs(iph->tot_len), 1))
 369                                 goto fail;
 370                 break;
 371         }
 372
 373         if (update_flags & TCA_CSUM_UPDATE_FLAG_IPV4HDR) {
 374                 if (skb_cloned(skb) &&
 375                     !skb_clone_writable(skb, sizeof(*iph) + ntkoff) &&
 376                     pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 377                         goto fail;
 378
 379                 ip_send_check(iph);
 380         }
 381
 382         return 1;
 383
 384 fail:
 385         return 0;
 386 }
 387
 388 static int tcf_csum_ipv6_hopopts(struct ipv6_opt_hdr *ip6xh,
 389                                   unsigned int ixhl, unsigned int *pl)
 390 {
 391         int off, len, optlen;
 392         unsigned char *xh = (void *)ip6xh;
 393
 394         off = sizeof(*ip6xh);
 395         len = ixhl - off;
 396
 397         while (len > 1) {
 398                 switch (xh[off])
 399                 {
 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,
 480                                                        hl, 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,
 486                                                        hl, 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                     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         p->tcf_bstats.bytes += qdisc_pkt_len(skb);
 512         p->tcf_bstats.packets++;
 513         action = p->tcf_action;
 514         update_flags = p->update_flags;
 515         spin_unlock(&p->tcf_lock);
 516
 517         if (unlikely(action == TC_ACT_SHOT))
 518                 goto drop;
 519
 520         switch (skb->protocol) {
 521         case cpu_to_be16(ETH_P_IP):
 522                 if (!tcf_csum_ipv4(skb, update_flags))
 523                         goto drop;
 524                 break;
 525         case cpu_to_be16(ETH_P_IPV6):
 526                 if (!tcf_csum_ipv6(skb, update_flags))
 527                         goto drop;
 528                 break;
 529         }
 530
 531         return action;
 532
 533 drop:
 534         spin_lock(&p->tcf_lock);
 535         p->tcf_qstats.drops++;
 536         spin_unlock(&p->tcf_lock);
 537         return TC_ACT_SHOT;
 538 }
 539
 540 static int tcf_csum_dump(struct sk_buff *skb,
 541                          struct tc_action *a, int bind, int ref)
 542 {
 543         unsigned char *b = skb_tail_pointer(skb);
 544         struct tcf_csum *p = a->priv;
 545         struct tc_csum opt = {
 546                 .update_flags = p->update_flags,
 547
 548                 .index   = p->tcf_index,
 549                 .action  = p->tcf_action,
 550                 .refcnt  = p->tcf_refcnt - ref,
 551                 .bindcnt = p->tcf_bindcnt - bind,
 552         };
 553         struct tcf_t t;
 554
 555         NLA_PUT(skb, TCA_CSUM_PARMS, sizeof(opt), &opt);
 556         t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
 557         t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
 558         t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
 559         NLA_PUT(skb, TCA_CSUM_TM, sizeof(t), &t);
 560
 561         return skb->len;
 562
 563 nla_put_failure:
 564         nlmsg_trim(skb, b);
 565         return -1;
 566 }
 567
 568 static struct tc_action_ops act_csum_ops = {
 569         .kind           =       "csum",
 570         .hinfo          =       &csum_hash_info,
 571         .type           =       TCA_ACT_CSUM,
 572         .capab          =       TCA_CAP_NONE,
 573         .owner          =       THIS_MODULE,
 574         .act            =       tcf_csum,
 575         .dump           =       tcf_csum_dump,
 576         .cleanup        =       tcf_csum_cleanup,
 577         .lookup         =       tcf_hash_search,
 578         .init           =       tcf_csum_init,
 579         .walk           =       tcf_generic_walker
 580 };
 581
 582 MODULE_DESCRIPTION("Checksum updating actions");
 583 MODULE_LICENSE("GPL");
 584
 585 static int __init csum_init_module(void)
 586 {
 587         return tcf_register_action(&act_csum_ops);
 588 }
 589
 590 static void __exit csum_cleanup_module(void)
 591 {
 592         tcf_unregister_action(&act_csum_ops);
 593 }
 594
 595 module_init(csum_init_module);
 596 module_exit(csum_cleanup_module);