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 #include <net/sctp/checksum.h> 34 35 #include <net/act_api.h> 36 37 #include <linux/tc_act/tc_csum.h> 38 #include <net/tc_act/tc_csum.h> 39 40 #define CSUM_TAB_MASK 15 41 42 static const struct nla_policy csum_policy[TCA_CSUM_MAX + 1] = { 43 [TCA_CSUM_PARMS] = { .len = sizeof(struct tc_csum), }, 44 }; 45 46 static unsigned int csum_net_id; 47 static struct tc_action_ops act_csum_ops; 48 49 static int tcf_csum_init(struct net *net, struct nlattr *nla, 50 struct nlattr *est, struct tc_action **a, int ovr, 51 int bind) 52 { 53 struct tc_action_net *tn = net_generic(net, csum_net_id); 54 struct nlattr *tb[TCA_CSUM_MAX + 1]; 55 struct tc_csum *parm; 56 struct tcf_csum *p; 57 int ret = 0, err; 58 59 if (nla == NULL) 60 return -EINVAL; 61 62 err = nla_parse_nested(tb, TCA_CSUM_MAX, nla, csum_policy); 63 if (err < 0) 64 return err; 65 66 if (tb[TCA_CSUM_PARMS] == NULL) 67 return -EINVAL; 68 parm = nla_data(tb[TCA_CSUM_PARMS]); 69 70 if (!tcf_hash_check(tn, parm->index, a, bind)) { 71 ret = tcf_hash_create(tn, parm->index, est, a, 72 &act_csum_ops, bind, false); 73 if (ret) 74 return ret; 75 ret = ACT_P_CREATED; 76 } else { 77 if (bind)/* dont override defaults */ 78 return 0; 79 tcf_hash_release(*a, bind); 80 if (!ovr) 81 return -EEXIST; 82 } 83 84 p = to_tcf_csum(*a); 85 spin_lock_bh(&p->tcf_lock); 86 p->tcf_action = parm->action; 87 p->update_flags = parm->update_flags; 88 spin_unlock_bh(&p->tcf_lock); 89 90 if (ret == ACT_P_CREATED) 91 tcf_hash_insert(tn, *a); 92 93 return ret; 94 } 95 96 /** 97 * tcf_csum_skb_nextlayer - Get next layer pointer 98 * @skb: sk_buff to use 99 * @ihl: previous summed headers length 100 * @ipl: complete packet length 101 * @jhl: next header length 102 * 103 * Check the expected next layer availability in the specified sk_buff. 104 * Return the next layer pointer if pass, NULL otherwise. 105 */ 106 static void *tcf_csum_skb_nextlayer(struct sk_buff *skb, 107 unsigned int ihl, unsigned int ipl, 108 unsigned int jhl) 109 { 110 int ntkoff = skb_network_offset(skb); 111 int hl = ihl + jhl; 112 113 if (!pskb_may_pull(skb, ipl + ntkoff) || (ipl < hl) || 114 skb_try_make_writable(skb, hl + ntkoff)) 115 return NULL; 116 else 117 return (void *)(skb_network_header(skb) + ihl); 118 } 119 120 static int tcf_csum_ipv4_icmp(struct sk_buff *skb, unsigned int ihl, 121 unsigned int ipl) 122 { 123 struct icmphdr *icmph; 124 125 icmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmph)); 126 if (icmph == NULL) 127 return 0; 128 129 icmph->checksum = 0; 130 skb->csum = csum_partial(icmph, ipl - ihl, 0); 131 icmph->checksum = csum_fold(skb->csum); 132 133 skb->ip_summed = CHECKSUM_NONE; 134 135 return 1; 136 } 137 138 static int tcf_csum_ipv4_igmp(struct sk_buff *skb, 139 unsigned int ihl, unsigned int ipl) 140 { 141 struct igmphdr *igmph; 142 143 igmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*igmph)); 144 if (igmph == NULL) 145 return 0; 146 147 igmph->csum = 0; 148 skb->csum = csum_partial(igmph, ipl - ihl, 0); 149 igmph->csum = csum_fold(skb->csum); 150 151 skb->ip_summed = CHECKSUM_NONE; 152 153 return 1; 154 } 155 156 static int tcf_csum_ipv6_icmp(struct sk_buff *skb, unsigned int ihl, 157 unsigned int ipl) 158 { 159 struct icmp6hdr *icmp6h; 160 const struct ipv6hdr *ip6h; 161 162 icmp6h = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmp6h)); 163 if (icmp6h == NULL) 164 return 0; 165 166 ip6h = ipv6_hdr(skb); 167 icmp6h->icmp6_cksum = 0; 168 skb->csum = csum_partial(icmp6h, ipl - ihl, 0); 169 icmp6h->icmp6_cksum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, 170 ipl - ihl, IPPROTO_ICMPV6, 171 skb->csum); 172 173 skb->ip_summed = CHECKSUM_NONE; 174 175 return 1; 176 } 177 178 static int tcf_csum_ipv4_tcp(struct sk_buff *skb, unsigned int ihl, 179 unsigned int ipl) 180 { 181 struct tcphdr *tcph; 182 const struct iphdr *iph; 183 184 tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph)); 185 if (tcph == NULL) 186 return 0; 187 188 iph = ip_hdr(skb); 189 tcph->check = 0; 190 skb->csum = csum_partial(tcph, ipl - ihl, 0); 191 tcph->check = tcp_v4_check(ipl - ihl, 192 iph->saddr, iph->daddr, skb->csum); 193 194 skb->ip_summed = CHECKSUM_NONE; 195 196 return 1; 197 } 198 199 static int tcf_csum_ipv6_tcp(struct sk_buff *skb, unsigned int ihl, 200 unsigned int ipl) 201 { 202 struct tcphdr *tcph; 203 const struct ipv6hdr *ip6h; 204 205 tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph)); 206 if (tcph == NULL) 207 return 0; 208 209 ip6h = ipv6_hdr(skb); 210 tcph->check = 0; 211 skb->csum = csum_partial(tcph, ipl - ihl, 0); 212 tcph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, 213 ipl - ihl, IPPROTO_TCP, 214 skb->csum); 215 216 skb->ip_summed = CHECKSUM_NONE; 217 218 return 1; 219 } 220 221 static int tcf_csum_ipv4_udp(struct sk_buff *skb, unsigned int ihl, 222 unsigned int ipl, int udplite) 223 { 224 struct udphdr *udph; 225 const struct iphdr *iph; 226 u16 ul; 227 228 /* 229 * Support both UDP and UDPLITE checksum algorithms, Don't use 230 * udph->len to get the real length without any protocol check, 231 * UDPLITE uses udph->len for another thing, 232 * Use iph->tot_len, or just ipl. 233 */ 234 235 udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph)); 236 if (udph == NULL) 237 return 0; 238 239 iph = ip_hdr(skb); 240 ul = ntohs(udph->len); 241 242 if (udplite || udph->check) { 243 244 udph->check = 0; 245 246 if (udplite) { 247 if (ul == 0) 248 skb->csum = csum_partial(udph, ipl - ihl, 0); 249 else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl)) 250 skb->csum = csum_partial(udph, ul, 0); 251 else 252 goto ignore_obscure_skb; 253 } else { 254 if (ul != ipl - ihl) 255 goto ignore_obscure_skb; 256 257 skb->csum = csum_partial(udph, ul, 0); 258 } 259 260 udph->check = csum_tcpudp_magic(iph->saddr, iph->daddr, 261 ul, iph->protocol, 262 skb->csum); 263 264 if (!udph->check) 265 udph->check = CSUM_MANGLED_0; 266 } 267 268 skb->ip_summed = CHECKSUM_NONE; 269 270 ignore_obscure_skb: 271 return 1; 272 } 273 274 static int tcf_csum_ipv6_udp(struct sk_buff *skb, unsigned int ihl, 275 unsigned int ipl, int udplite) 276 { 277 struct udphdr *udph; 278 const struct ipv6hdr *ip6h; 279 u16 ul; 280 281 /* 282 * Support both UDP and UDPLITE checksum algorithms, Don't use 283 * udph->len to get the real length without any protocol check, 284 * UDPLITE uses udph->len for another thing, 285 * Use ip6h->payload_len + sizeof(*ip6h) ... , or just ipl. 286 */ 287 288 udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph)); 289 if (udph == NULL) 290 return 0; 291 292 ip6h = ipv6_hdr(skb); 293 ul = ntohs(udph->len); 294 295 udph->check = 0; 296 297 if (udplite) { 298 if (ul == 0) 299 skb->csum = csum_partial(udph, ipl - ihl, 0); 300 301 else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl)) 302 skb->csum = csum_partial(udph, ul, 0); 303 304 else 305 goto ignore_obscure_skb; 306 } else { 307 if (ul != ipl - ihl) 308 goto ignore_obscure_skb; 309 310 skb->csum = csum_partial(udph, ul, 0); 311 } 312 313 udph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, ul, 314 udplite ? IPPROTO_UDPLITE : IPPROTO_UDP, 315 skb->csum); 316 317 if (!udph->check) 318 udph->check = CSUM_MANGLED_0; 319 320 skb->ip_summed = CHECKSUM_NONE; 321 322 ignore_obscure_skb: 323 return 1; 324 } 325 326 static int tcf_csum_sctp(struct sk_buff *skb, unsigned int ihl, 327 unsigned int ipl) 328 { 329 struct sctphdr *sctph; 330 331 if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_SCTP) 332 return 1; 333 334 sctph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*sctph)); 335 if (!sctph) 336 return 0; 337 338 sctph->checksum = sctp_compute_cksum(skb, 339 skb_network_offset(skb) + ihl); 340 skb->ip_summed = CHECKSUM_NONE; 341 342 return 1; 343 } 344 345 static int tcf_csum_ipv4(struct sk_buff *skb, u32 update_flags) 346 { 347 const struct iphdr *iph; 348 int ntkoff; 349 350 ntkoff = skb_network_offset(skb); 351 352 if (!pskb_may_pull(skb, sizeof(*iph) + ntkoff)) 353 goto fail; 354 355 iph = ip_hdr(skb); 356 357 switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) { 358 case IPPROTO_ICMP: 359 if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP) 360 if (!tcf_csum_ipv4_icmp(skb, iph->ihl * 4, 361 ntohs(iph->tot_len))) 362 goto fail; 363 break; 364 case IPPROTO_IGMP: 365 if (update_flags & TCA_CSUM_UPDATE_FLAG_IGMP) 366 if (!tcf_csum_ipv4_igmp(skb, iph->ihl * 4, 367 ntohs(iph->tot_len))) 368 goto fail; 369 break; 370 case IPPROTO_TCP: 371 if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP) 372 if (!tcf_csum_ipv4_tcp(skb, iph->ihl * 4, 373 ntohs(iph->tot_len))) 374 goto fail; 375 break; 376 case IPPROTO_UDP: 377 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP) 378 if (!tcf_csum_ipv4_udp(skb, iph->ihl * 4, 379 ntohs(iph->tot_len), 0)) 380 goto fail; 381 break; 382 case IPPROTO_UDPLITE: 383 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE) 384 if (!tcf_csum_ipv4_udp(skb, iph->ihl * 4, 385 ntohs(iph->tot_len), 1)) 386 goto fail; 387 break; 388 case IPPROTO_SCTP: 389 if ((update_flags & TCA_CSUM_UPDATE_FLAG_SCTP) && 390 !tcf_csum_sctp(skb, iph->ihl * 4, ntohs(iph->tot_len))) 391 goto fail; 392 break; 393 } 394 395 if (update_flags & TCA_CSUM_UPDATE_FLAG_IPV4HDR) { 396 if (skb_try_make_writable(skb, sizeof(*iph) + ntkoff)) 397 goto fail; 398 399 ip_send_check(ip_hdr(skb)); 400 } 401 402 return 1; 403 404 fail: 405 return 0; 406 } 407 408 static int tcf_csum_ipv6_hopopts(struct ipv6_opt_hdr *ip6xh, unsigned int ixhl, 409 unsigned int *pl) 410 { 411 int off, len, optlen; 412 unsigned char *xh = (void *)ip6xh; 413 414 off = sizeof(*ip6xh); 415 len = ixhl - off; 416 417 while (len > 1) { 418 switch (xh[off]) { 419 case IPV6_TLV_PAD1: 420 optlen = 1; 421 break; 422 case IPV6_TLV_JUMBO: 423 optlen = xh[off + 1] + 2; 424 if (optlen != 6 || len < 6 || (off & 3) != 2) 425 /* wrong jumbo option length/alignment */ 426 return 0; 427 *pl = ntohl(*(__be32 *)(xh + off + 2)); 428 goto done; 429 default: 430 optlen = xh[off + 1] + 2; 431 if (optlen > len) 432 /* ignore obscure options */ 433 goto done; 434 break; 435 } 436 off += optlen; 437 len -= optlen; 438 } 439 440 done: 441 return 1; 442 } 443 444 static int tcf_csum_ipv6(struct sk_buff *skb, u32 update_flags) 445 { 446 struct ipv6hdr *ip6h; 447 struct ipv6_opt_hdr *ip6xh; 448 unsigned int hl, ixhl; 449 unsigned int pl; 450 int ntkoff; 451 u8 nexthdr; 452 453 ntkoff = skb_network_offset(skb); 454 455 hl = sizeof(*ip6h); 456 457 if (!pskb_may_pull(skb, hl + ntkoff)) 458 goto fail; 459 460 ip6h = ipv6_hdr(skb); 461 462 pl = ntohs(ip6h->payload_len); 463 nexthdr = ip6h->nexthdr; 464 465 do { 466 switch (nexthdr) { 467 case NEXTHDR_FRAGMENT: 468 goto ignore_skb; 469 case NEXTHDR_ROUTING: 470 case NEXTHDR_HOP: 471 case NEXTHDR_DEST: 472 if (!pskb_may_pull(skb, hl + sizeof(*ip6xh) + ntkoff)) 473 goto fail; 474 ip6xh = (void *)(skb_network_header(skb) + hl); 475 ixhl = ipv6_optlen(ip6xh); 476 if (!pskb_may_pull(skb, hl + ixhl + ntkoff)) 477 goto fail; 478 ip6xh = (void *)(skb_network_header(skb) + hl); 479 if ((nexthdr == NEXTHDR_HOP) && 480 !(tcf_csum_ipv6_hopopts(ip6xh, ixhl, &pl))) 481 goto fail; 482 nexthdr = ip6xh->nexthdr; 483 hl += ixhl; 484 break; 485 case IPPROTO_ICMPV6: 486 if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP) 487 if (!tcf_csum_ipv6_icmp(skb, 488 hl, pl + sizeof(*ip6h))) 489 goto fail; 490 goto done; 491 case IPPROTO_TCP: 492 if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP) 493 if (!tcf_csum_ipv6_tcp(skb, 494 hl, pl + sizeof(*ip6h))) 495 goto fail; 496 goto done; 497 case IPPROTO_UDP: 498 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP) 499 if (!tcf_csum_ipv6_udp(skb, hl, 500 pl + sizeof(*ip6h), 0)) 501 goto fail; 502 goto done; 503 case IPPROTO_UDPLITE: 504 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE) 505 if (!tcf_csum_ipv6_udp(skb, hl, 506 pl + sizeof(*ip6h), 1)) 507 goto fail; 508 goto done; 509 case IPPROTO_SCTP: 510 if ((update_flags & TCA_CSUM_UPDATE_FLAG_SCTP) && 511 !tcf_csum_sctp(skb, hl, pl + sizeof(*ip6h))) 512 goto fail; 513 goto done; 514 default: 515 goto ignore_skb; 516 } 517 } while (pskb_may_pull(skb, hl + 1 + ntkoff)); 518 519 done: 520 ignore_skb: 521 return 1; 522 523 fail: 524 return 0; 525 } 526 527 static int tcf_csum(struct sk_buff *skb, const struct tc_action *a, 528 struct tcf_result *res) 529 { 530 struct tcf_csum *p = to_tcf_csum(a); 531 int action; 532 u32 update_flags; 533 534 spin_lock(&p->tcf_lock); 535 tcf_lastuse_update(&p->tcf_tm); 536 bstats_update(&p->tcf_bstats, skb); 537 action = p->tcf_action; 538 update_flags = p->update_flags; 539 spin_unlock(&p->tcf_lock); 540 541 if (unlikely(action == TC_ACT_SHOT)) 542 goto drop; 543 544 switch (tc_skb_protocol(skb)) { 545 case cpu_to_be16(ETH_P_IP): 546 if (!tcf_csum_ipv4(skb, update_flags)) 547 goto drop; 548 break; 549 case cpu_to_be16(ETH_P_IPV6): 550 if (!tcf_csum_ipv6(skb, update_flags)) 551 goto drop; 552 break; 553 } 554 555 return action; 556 557 drop: 558 spin_lock(&p->tcf_lock); 559 p->tcf_qstats.drops++; 560 spin_unlock(&p->tcf_lock); 561 return TC_ACT_SHOT; 562 } 563 564 static int tcf_csum_dump(struct sk_buff *skb, struct tc_action *a, int bind, 565 int ref) 566 { 567 unsigned char *b = skb_tail_pointer(skb); 568 struct tcf_csum *p = to_tcf_csum(a); 569 struct tc_csum opt = { 570 .update_flags = p->update_flags, 571 .index = p->tcf_index, 572 .action = p->tcf_action, 573 .refcnt = p->tcf_refcnt - ref, 574 .bindcnt = p->tcf_bindcnt - bind, 575 }; 576 struct tcf_t t; 577 578 if (nla_put(skb, TCA_CSUM_PARMS, sizeof(opt), &opt)) 579 goto nla_put_failure; 580 581 tcf_tm_dump(&t, &p->tcf_tm); 582 if (nla_put_64bit(skb, TCA_CSUM_TM, sizeof(t), &t, TCA_CSUM_PAD)) 583 goto nla_put_failure; 584 585 return skb->len; 586 587 nla_put_failure: 588 nlmsg_trim(skb, b); 589 return -1; 590 } 591 592 static int tcf_csum_walker(struct net *net, struct sk_buff *skb, 593 struct netlink_callback *cb, int type, 594 const struct tc_action_ops *ops) 595 { 596 struct tc_action_net *tn = net_generic(net, csum_net_id); 597 598 return tcf_generic_walker(tn, skb, cb, type, ops); 599 } 600 601 static int tcf_csum_search(struct net *net, struct tc_action **a, u32 index) 602 { 603 struct tc_action_net *tn = net_generic(net, csum_net_id); 604 605 return tcf_hash_search(tn, a, index); 606 } 607 608 static struct tc_action_ops act_csum_ops = { 609 .kind = "csum", 610 .type = TCA_ACT_CSUM, 611 .owner = THIS_MODULE, 612 .act = tcf_csum, 613 .dump = tcf_csum_dump, 614 .init = tcf_csum_init, 615 .walk = tcf_csum_walker, 616 .lookup = tcf_csum_search, 617 .size = sizeof(struct tcf_csum), 618 }; 619 620 static __net_init int csum_init_net(struct net *net) 621 { 622 struct tc_action_net *tn = net_generic(net, csum_net_id); 623 624 return tc_action_net_init(tn, &act_csum_ops, CSUM_TAB_MASK); 625 } 626 627 static void __net_exit csum_exit_net(struct net *net) 628 { 629 struct tc_action_net *tn = net_generic(net, csum_net_id); 630 631 tc_action_net_exit(tn); 632 } 633 634 static struct pernet_operations csum_net_ops = { 635 .init = csum_init_net, 636 .exit = csum_exit_net, 637 .id = &csum_net_id, 638 .size = sizeof(struct tc_action_net), 639 }; 640 641 MODULE_DESCRIPTION("Checksum updating actions"); 642 MODULE_LICENSE("GPL"); 643 644 static int __init csum_init_module(void) 645 { 646 return tcf_register_action(&act_csum_ops, &csum_net_ops); 647 } 648 649 static void __exit csum_cleanup_module(void) 650 { 651 tcf_unregister_action(&act_csum_ops, &csum_net_ops); 652 } 653 654 module_init(csum_init_module); 655 module_exit(csum_cleanup_module); 656