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