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