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, 77 &csum_idx_gen, &csum_hash_info); 78 if (IS_ERR(pc)) 79 return PTR_ERR(pc); 80 p = to_tcf_csum(pc); 81 ret = ACT_P_CREATED; 82 } else { 83 p = to_tcf_csum(pc); 84 if (!ovr) { 85 tcf_hash_release(pc, bind, &csum_hash_info); 86 return -EEXIST; 87 } 88 } 89 90 spin_lock_bh(&p->tcf_lock); 91 p->tcf_action = parm->action; 92 p->update_flags = parm->update_flags; 93 spin_unlock_bh(&p->tcf_lock); 94 95 if (ret == ACT_P_CREATED) 96 tcf_hash_insert(pc, &csum_hash_info); 97 98 return ret; 99 } 100 101 static int tcf_csum_cleanup(struct tc_action *a, int bind) 102 { 103 struct tcf_csum *p = a->priv; 104 return tcf_hash_release(&p->common, bind, &csum_hash_info); 105 } 106 107 /** 108 * tcf_csum_skb_nextlayer - Get next layer pointer 109 * @skb: sk_buff to use 110 * @ihl: previous summed headers length 111 * @ipl: complete packet length 112 * @jhl: next header length 113 * 114 * Check the expected next layer availability in the specified sk_buff. 115 * Return the next layer pointer if pass, NULL otherwise. 116 */ 117 static void *tcf_csum_skb_nextlayer(struct sk_buff *skb, 118 unsigned int ihl, unsigned int ipl, 119 unsigned int jhl) 120 { 121 int ntkoff = skb_network_offset(skb); 122 int hl = ihl + jhl; 123 124 if (!pskb_may_pull(skb, ipl + ntkoff) || (ipl < hl) || 125 (skb_cloned(skb) && 126 !skb_clone_writable(skb, hl + ntkoff) && 127 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))) 128 return NULL; 129 else 130 return (void *)(skb_network_header(skb) + ihl); 131 } 132 133 static int tcf_csum_ipv4_icmp(struct sk_buff *skb, 134 unsigned int ihl, unsigned int ipl) 135 { 136 struct icmphdr *icmph; 137 138 icmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmph)); 139 if (icmph == NULL) 140 return 0; 141 142 icmph->checksum = 0; 143 skb->csum = csum_partial(icmph, ipl - ihl, 0); 144 icmph->checksum = csum_fold(skb->csum); 145 146 skb->ip_summed = CHECKSUM_NONE; 147 148 return 1; 149 } 150 151 static int tcf_csum_ipv4_igmp(struct sk_buff *skb, 152 unsigned int ihl, unsigned int ipl) 153 { 154 struct igmphdr *igmph; 155 156 igmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*igmph)); 157 if (igmph == NULL) 158 return 0; 159 160 igmph->csum = 0; 161 skb->csum = csum_partial(igmph, ipl - ihl, 0); 162 igmph->csum = csum_fold(skb->csum); 163 164 skb->ip_summed = CHECKSUM_NONE; 165 166 return 1; 167 } 168 169 static int tcf_csum_ipv6_icmp(struct sk_buff *skb, struct ipv6hdr *ip6h, 170 unsigned int ihl, unsigned int ipl) 171 { 172 struct icmp6hdr *icmp6h; 173 174 icmp6h = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmp6h)); 175 if (icmp6h == NULL) 176 return 0; 177 178 icmp6h->icmp6_cksum = 0; 179 skb->csum = csum_partial(icmp6h, ipl - ihl, 0); 180 icmp6h->icmp6_cksum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, 181 ipl - ihl, IPPROTO_ICMPV6, 182 skb->csum); 183 184 skb->ip_summed = CHECKSUM_NONE; 185 186 return 1; 187 } 188 189 static int tcf_csum_ipv4_tcp(struct sk_buff *skb, struct iphdr *iph, 190 unsigned int ihl, unsigned int ipl) 191 { 192 struct tcphdr *tcph; 193 194 tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph)); 195 if (tcph == NULL) 196 return 0; 197 198 tcph->check = 0; 199 skb->csum = csum_partial(tcph, ipl - ihl, 0); 200 tcph->check = tcp_v4_check(ipl - ihl, 201 iph->saddr, iph->daddr, skb->csum); 202 203 skb->ip_summed = CHECKSUM_NONE; 204 205 return 1; 206 } 207 208 static int tcf_csum_ipv6_tcp(struct sk_buff *skb, struct ipv6hdr *ip6h, 209 unsigned int ihl, unsigned int ipl) 210 { 211 struct tcphdr *tcph; 212 213 tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph)); 214 if (tcph == NULL) 215 return 0; 216 217 tcph->check = 0; 218 skb->csum = csum_partial(tcph, ipl - ihl, 0); 219 tcph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, 220 ipl - ihl, IPPROTO_TCP, 221 skb->csum); 222 223 skb->ip_summed = CHECKSUM_NONE; 224 225 return 1; 226 } 227 228 static int tcf_csum_ipv4_udp(struct sk_buff *skb, struct iphdr *iph, 229 unsigned int ihl, unsigned int ipl, int udplite) 230 { 231 struct udphdr *udph; 232 u16 ul; 233 234 /* 235 * Support both UDP and UDPLITE checksum algorithms, Don't use 236 * udph->len to get the real length without any protocol check, 237 * UDPLITE uses udph->len for another thing, 238 * Use iph->tot_len, or just ipl. 239 */ 240 241 udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph)); 242 if (udph == NULL) 243 return 0; 244 245 ul = ntohs(udph->len); 246 247 if (udplite || udph->check) { 248 249 udph->check = 0; 250 251 if (udplite) { 252 if (ul == 0) 253 skb->csum = csum_partial(udph, ipl - ihl, 0); 254 else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl)) 255 skb->csum = csum_partial(udph, ul, 0); 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 /* 286 * Support both UDP and UDPLITE checksum algorithms, Don't use 287 * udph->len to get the real length without any protocol check, 288 * UDPLITE uses udph->len for another thing, 289 * Use ip6h->payload_len + sizeof(*ip6h) ... , or just ipl. 290 */ 291 292 udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph)); 293 if (udph == NULL) 294 return 0; 295 296 ul = ntohs(udph->len); 297 298 udph->check = 0; 299 300 if (udplite) { 301 if (ul == 0) 302 skb->csum = csum_partial(udph, ipl - ihl, 0); 303 304 else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl)) 305 skb->csum = csum_partial(udph, ul, 0); 306 307 else 308 goto ignore_obscure_skb; 309 } else { 310 if (ul != ipl - ihl) 311 goto ignore_obscure_skb; 312 313 skb->csum = csum_partial(udph, ul, 0); 314 } 315 316 udph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, ul, 317 udplite ? IPPROTO_UDPLITE : IPPROTO_UDP, 318 skb->csum); 319 320 if (!udph->check) 321 udph->check = CSUM_MANGLED_0; 322 323 skb->ip_summed = CHECKSUM_NONE; 324 325 ignore_obscure_skb: 326 return 1; 327 } 328 329 static int tcf_csum_ipv4(struct sk_buff *skb, u32 update_flags) 330 { 331 struct iphdr *iph; 332 int ntkoff; 333 334 ntkoff = skb_network_offset(skb); 335 336 if (!pskb_may_pull(skb, sizeof(*iph) + ntkoff)) 337 goto fail; 338 339 iph = ip_hdr(skb); 340 341 switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) { 342 case IPPROTO_ICMP: 343 if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP) 344 if (!tcf_csum_ipv4_icmp(skb, iph->ihl * 4, 345 ntohs(iph->tot_len))) 346 goto fail; 347 break; 348 case IPPROTO_IGMP: 349 if (update_flags & TCA_CSUM_UPDATE_FLAG_IGMP) 350 if (!tcf_csum_ipv4_igmp(skb, iph->ihl * 4, 351 ntohs(iph->tot_len))) 352 goto fail; 353 break; 354 case IPPROTO_TCP: 355 if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP) 356 if (!tcf_csum_ipv4_tcp(skb, iph, iph->ihl * 4, 357 ntohs(iph->tot_len))) 358 goto fail; 359 break; 360 case IPPROTO_UDP: 361 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP) 362 if (!tcf_csum_ipv4_udp(skb, iph, iph->ihl * 4, 363 ntohs(iph->tot_len), 0)) 364 goto fail; 365 break; 366 case IPPROTO_UDPLITE: 367 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE) 368 if (!tcf_csum_ipv4_udp(skb, iph, iph->ihl * 4, 369 ntohs(iph->tot_len), 1)) 370 goto fail; 371 break; 372 } 373 374 if (update_flags & TCA_CSUM_UPDATE_FLAG_IPV4HDR) { 375 if (skb_cloned(skb) && 376 !skb_clone_writable(skb, sizeof(*iph) + ntkoff) && 377 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 378 goto fail; 379 380 ip_send_check(iph); 381 } 382 383 return 1; 384 385 fail: 386 return 0; 387 } 388 389 static int tcf_csum_ipv6_hopopts(struct ipv6_opt_hdr *ip6xh, 390 unsigned int ixhl, unsigned int *pl) 391 { 392 int off, len, optlen; 393 unsigned char *xh = (void *)ip6xh; 394 395 off = sizeof(*ip6xh); 396 len = ixhl - off; 397 398 while (len > 1) { 399 switch (xh[off]) { 400 case IPV6_TLV_PAD1: 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, hl, 480 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, hl, 486 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 const 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 bstats_update(&p->tcf_bstats, skb); 512 action = p->tcf_action; 513 update_flags = p->update_flags; 514 spin_unlock(&p->tcf_lock); 515 516 if (unlikely(action == TC_ACT_SHOT)) 517 goto drop; 518 519 switch (skb->protocol) { 520 case cpu_to_be16(ETH_P_IP): 521 if (!tcf_csum_ipv4(skb, update_flags)) 522 goto drop; 523 break; 524 case cpu_to_be16(ETH_P_IPV6): 525 if (!tcf_csum_ipv6(skb, update_flags)) 526 goto drop; 527 break; 528 } 529 530 return action; 531 532 drop: 533 spin_lock(&p->tcf_lock); 534 p->tcf_qstats.drops++; 535 spin_unlock(&p->tcf_lock); 536 return TC_ACT_SHOT; 537 } 538 539 static int tcf_csum_dump(struct sk_buff *skb, 540 struct tc_action *a, int bind, int ref) 541 { 542 unsigned char *b = skb_tail_pointer(skb); 543 struct tcf_csum *p = a->priv; 544 struct tc_csum opt = { 545 .update_flags = p->update_flags, 546 .index = p->tcf_index, 547 .action = p->tcf_action, 548 .refcnt = p->tcf_refcnt - ref, 549 .bindcnt = p->tcf_bindcnt - bind, 550 }; 551 struct tcf_t t; 552 553 if (nla_put(skb, TCA_CSUM_PARMS, sizeof(opt), &opt)) 554 goto nla_put_failure; 555 t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install); 556 t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse); 557 t.expires = jiffies_to_clock_t(p->tcf_tm.expires); 558 if (nla_put(skb, TCA_CSUM_TM, sizeof(t), &t)) 559 goto nla_put_failure; 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); 597