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