1 /* 2 * Copyright (C)2002 USAGI/WIDE Project 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, write to the Free Software 16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 17 * 18 * Authors 19 * 20 * Mitsuru KANDA @USAGI : IPv6 Support 21 * Kazunori MIYAZAWA @USAGI : 22 * Kunihiro Ishiguro <kunihiro@ipinfusion.com> 23 * 24 * This file is derived from net/ipv4/ah.c. 25 */ 26 27 #include <linux/module.h> 28 #include <net/ip.h> 29 #include <net/ah.h> 30 #include <linux/crypto.h> 31 #include <linux/pfkeyv2.h> 32 #include <linux/spinlock.h> 33 #include <linux/string.h> 34 #include <net/icmp.h> 35 #include <net/ipv6.h> 36 #include <net/protocol.h> 37 #include <net/xfrm.h> 38 39 static int zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr) 40 { 41 u8 *opt = (u8 *)opthdr; 42 int len = ipv6_optlen(opthdr); 43 int off = 0; 44 int optlen = 0; 45 46 off += 2; 47 len -= 2; 48 49 while (len > 0) { 50 51 switch (opt[off]) { 52 53 case IPV6_TLV_PAD0: 54 optlen = 1; 55 break; 56 default: 57 if (len < 2) 58 goto bad; 59 optlen = opt[off+1]+2; 60 if (len < optlen) 61 goto bad; 62 if (opt[off] & 0x20) 63 memset(&opt[off+2], 0, opt[off+1]); 64 break; 65 } 66 67 off += optlen; 68 len -= optlen; 69 } 70 if (len == 0) 71 return 1; 72 73 bad: 74 return 0; 75 } 76 77 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE) 78 /** 79 * ipv6_rearrange_destopt - rearrange IPv6 destination options header 80 * @iph: IPv6 header 81 * @destopt: destionation options header 82 */ 83 static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt) 84 { 85 u8 *opt = (u8 *)destopt; 86 int len = ipv6_optlen(destopt); 87 int off = 0; 88 int optlen = 0; 89 90 off += 2; 91 len -= 2; 92 93 while (len > 0) { 94 95 switch (opt[off]) { 96 97 case IPV6_TLV_PAD0: 98 optlen = 1; 99 break; 100 default: 101 if (len < 2) 102 goto bad; 103 optlen = opt[off+1]+2; 104 if (len < optlen) 105 goto bad; 106 107 /* Rearrange the source address in @iph and the 108 * addresses in home address option for final source. 109 * See 11.3.2 of RFC 3775 for details. 110 */ 111 if (opt[off] == IPV6_TLV_HAO) { 112 struct in6_addr final_addr; 113 struct ipv6_destopt_hao *hao; 114 115 hao = (struct ipv6_destopt_hao *)&opt[off]; 116 if (hao->length != sizeof(hao->addr)) { 117 if (net_ratelimit()) 118 printk(KERN_WARNING "destopt hao: invalid header length: %u\n", hao->length); 119 goto bad; 120 } 121 ipv6_addr_copy(&final_addr, &hao->addr); 122 ipv6_addr_copy(&hao->addr, &iph->saddr); 123 ipv6_addr_copy(&iph->saddr, &final_addr); 124 } 125 break; 126 } 127 128 off += optlen; 129 len -= optlen; 130 } 131 /* Note: ok if len == 0 */ 132 bad: 133 return; 134 } 135 #else 136 static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt) {} 137 #endif 138 139 /** 140 * ipv6_rearrange_rthdr - rearrange IPv6 routing header 141 * @iph: IPv6 header 142 * @rthdr: routing header 143 * 144 * Rearrange the destination address in @iph and the addresses in @rthdr 145 * so that they appear in the order they will at the final destination. 146 * See Appendix A2 of RFC 2402 for details. 147 */ 148 static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr) 149 { 150 int segments, segments_left; 151 struct in6_addr *addrs; 152 struct in6_addr final_addr; 153 154 segments_left = rthdr->segments_left; 155 if (segments_left == 0) 156 return; 157 rthdr->segments_left = 0; 158 159 /* The value of rthdr->hdrlen has been verified either by the system 160 * call if it is locally generated, or by ipv6_rthdr_rcv() for incoming 161 * packets. So we can assume that it is even and that segments is 162 * greater than or equal to segments_left. 163 * 164 * For the same reason we can assume that this option is of type 0. 165 */ 166 segments = rthdr->hdrlen >> 1; 167 168 addrs = ((struct rt0_hdr *)rthdr)->addr; 169 ipv6_addr_copy(&final_addr, addrs + segments - 1); 170 171 addrs += segments - segments_left; 172 memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs)); 173 174 ipv6_addr_copy(addrs, &iph->daddr); 175 ipv6_addr_copy(&iph->daddr, &final_addr); 176 } 177 178 static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len, int dir) 179 { 180 union { 181 struct ipv6hdr *iph; 182 struct ipv6_opt_hdr *opth; 183 struct ipv6_rt_hdr *rth; 184 char *raw; 185 } exthdr = { .iph = iph }; 186 char *end = exthdr.raw + len; 187 int nexthdr = iph->nexthdr; 188 189 exthdr.iph++; 190 191 while (exthdr.raw < end) { 192 switch (nexthdr) { 193 case NEXTHDR_DEST: 194 if (dir == XFRM_POLICY_OUT) 195 ipv6_rearrange_destopt(iph, exthdr.opth); 196 case NEXTHDR_HOP: 197 if (!zero_out_mutable_opts(exthdr.opth)) { 198 LIMIT_NETDEBUG( 199 KERN_WARNING "overrun %sopts\n", 200 nexthdr == NEXTHDR_HOP ? 201 "hop" : "dest"); 202 return -EINVAL; 203 } 204 break; 205 206 case NEXTHDR_ROUTING: 207 ipv6_rearrange_rthdr(iph, exthdr.rth); 208 break; 209 210 default : 211 return 0; 212 } 213 214 nexthdr = exthdr.opth->nexthdr; 215 exthdr.raw += ipv6_optlen(exthdr.opth); 216 } 217 218 return 0; 219 } 220 221 static int ah6_output(struct xfrm_state *x, struct sk_buff *skb) 222 { 223 int err; 224 int extlen; 225 struct ipv6hdr *top_iph; 226 struct ip_auth_hdr *ah; 227 struct ah_data *ahp; 228 u8 nexthdr; 229 char tmp_base[8]; 230 struct { 231 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE) 232 struct in6_addr saddr; 233 #endif 234 struct in6_addr daddr; 235 char hdrs[0]; 236 } *tmp_ext; 237 238 skb_push(skb, -skb_network_offset(skb)); 239 top_iph = ipv6_hdr(skb); 240 top_iph->payload_len = htons(skb->len - sizeof(*top_iph)); 241 242 nexthdr = *skb_mac_header(skb); 243 *skb_mac_header(skb) = IPPROTO_AH; 244 245 /* When there are no extension headers, we only need to save the first 246 * 8 bytes of the base IP header. 247 */ 248 memcpy(tmp_base, top_iph, sizeof(tmp_base)); 249 250 tmp_ext = NULL; 251 extlen = skb_transport_offset(skb) - sizeof(struct ipv6hdr); 252 if (extlen) { 253 extlen += sizeof(*tmp_ext); 254 tmp_ext = kmalloc(extlen, GFP_ATOMIC); 255 if (!tmp_ext) { 256 err = -ENOMEM; 257 goto error; 258 } 259 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE) 260 memcpy(tmp_ext, &top_iph->saddr, extlen); 261 #else 262 memcpy(tmp_ext, &top_iph->daddr, extlen); 263 #endif 264 err = ipv6_clear_mutable_options(top_iph, 265 extlen - sizeof(*tmp_ext) + 266 sizeof(*top_iph), 267 XFRM_POLICY_OUT); 268 if (err) 269 goto error_free_iph; 270 } 271 272 ah = ip_auth_hdr(skb); 273 ah->nexthdr = nexthdr; 274 275 top_iph->priority = 0; 276 top_iph->flow_lbl[0] = 0; 277 top_iph->flow_lbl[1] = 0; 278 top_iph->flow_lbl[2] = 0; 279 top_iph->hop_limit = 0; 280 281 ahp = x->data; 282 ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2; 283 284 ah->reserved = 0; 285 ah->spi = x->id.spi; 286 ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output); 287 288 spin_lock_bh(&x->lock); 289 err = ah_mac_digest(ahp, skb, ah->auth_data); 290 memcpy(ah->auth_data, ahp->work_icv, ahp->icv_trunc_len); 291 spin_unlock_bh(&x->lock); 292 293 if (err) 294 goto error_free_iph; 295 296 memcpy(top_iph, tmp_base, sizeof(tmp_base)); 297 if (tmp_ext) { 298 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE) 299 memcpy(&top_iph->saddr, tmp_ext, extlen); 300 #else 301 memcpy(&top_iph->daddr, tmp_ext, extlen); 302 #endif 303 error_free_iph: 304 kfree(tmp_ext); 305 } 306 307 error: 308 return err; 309 } 310 311 static int ah6_input(struct xfrm_state *x, struct sk_buff *skb) 312 { 313 /* 314 * Before process AH 315 * [IPv6][Ext1][Ext2][AH][Dest][Payload] 316 * |<-------------->| hdr_len 317 * 318 * To erase AH: 319 * Keeping copy of cleared headers. After AH processing, 320 * Moving the pointer of skb->network_header by using skb_pull as long 321 * as AH header length. Then copy back the copy as long as hdr_len 322 * If destination header following AH exists, copy it into after [Ext2]. 323 * 324 * |<>|[IPv6][Ext1][Ext2][Dest][Payload] 325 * There is offset of AH before IPv6 header after the process. 326 */ 327 328 struct ip_auth_hdr *ah; 329 struct ipv6hdr *ip6h; 330 struct ah_data *ahp; 331 unsigned char *tmp_hdr = NULL; 332 u16 hdr_len; 333 u16 ah_hlen; 334 int nexthdr; 335 int err = -EINVAL; 336 337 if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr))) 338 goto out; 339 340 /* We are going to _remove_ AH header to keep sockets happy, 341 * so... Later this can change. */ 342 if (skb_cloned(skb) && 343 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 344 goto out; 345 346 skb->ip_summed = CHECKSUM_NONE; 347 348 hdr_len = skb->data - skb_network_header(skb); 349 ah = (struct ip_auth_hdr *)skb->data; 350 ahp = x->data; 351 nexthdr = ah->nexthdr; 352 ah_hlen = (ah->hdrlen + 2) << 2; 353 354 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) && 355 ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len)) 356 goto out; 357 358 if (!pskb_may_pull(skb, ah_hlen)) 359 goto out; 360 361 tmp_hdr = kmemdup(skb_network_header(skb), hdr_len, GFP_ATOMIC); 362 if (!tmp_hdr) 363 goto out; 364 ip6h = ipv6_hdr(skb); 365 if (ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN)) 366 goto free_out; 367 ip6h->priority = 0; 368 ip6h->flow_lbl[0] = 0; 369 ip6h->flow_lbl[1] = 0; 370 ip6h->flow_lbl[2] = 0; 371 ip6h->hop_limit = 0; 372 373 spin_lock(&x->lock); 374 { 375 u8 auth_data[MAX_AH_AUTH_LEN]; 376 377 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); 378 memset(ah->auth_data, 0, ahp->icv_trunc_len); 379 skb_push(skb, hdr_len); 380 err = ah_mac_digest(ahp, skb, ah->auth_data); 381 if (err) 382 goto unlock; 383 if (memcmp(ahp->work_icv, auth_data, ahp->icv_trunc_len)) 384 err = -EBADMSG; 385 } 386 unlock: 387 spin_unlock(&x->lock); 388 389 if (err) 390 goto free_out; 391 392 skb->network_header += ah_hlen; 393 memcpy(skb_network_header(skb), tmp_hdr, hdr_len); 394 skb->transport_header = skb->network_header; 395 __skb_pull(skb, ah_hlen + hdr_len); 396 397 kfree(tmp_hdr); 398 399 return nexthdr; 400 401 free_out: 402 kfree(tmp_hdr); 403 out: 404 return err; 405 } 406 407 static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 408 int type, int code, int offset, __be32 info) 409 { 410 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 411 struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+offset); 412 struct xfrm_state *x; 413 414 if (type != ICMPV6_DEST_UNREACH && 415 type != ICMPV6_PKT_TOOBIG) 416 return; 417 418 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6); 419 if (!x) 420 return; 421 422 NETDEBUG(KERN_DEBUG "pmtu discovery on SA AH/%08x/" NIP6_FMT "\n", 423 ntohl(ah->spi), NIP6(iph->daddr)); 424 425 xfrm_state_put(x); 426 } 427 428 static int ah6_init_state(struct xfrm_state *x) 429 { 430 struct ah_data *ahp = NULL; 431 struct xfrm_algo_desc *aalg_desc; 432 struct crypto_hash *tfm; 433 434 if (!x->aalg) 435 goto error; 436 437 if (x->encap) 438 goto error; 439 440 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL); 441 if (ahp == NULL) 442 return -ENOMEM; 443 444 tfm = crypto_alloc_hash(x->aalg->alg_name, 0, CRYPTO_ALG_ASYNC); 445 if (IS_ERR(tfm)) 446 goto error; 447 448 ahp->tfm = tfm; 449 if (crypto_hash_setkey(tfm, x->aalg->alg_key, 450 (x->aalg->alg_key_len + 7) / 8)) 451 goto error; 452 453 /* 454 * Lookup the algorithm description maintained by xfrm_algo, 455 * verify crypto transform properties, and store information 456 * we need for AH processing. This lookup cannot fail here 457 * after a successful crypto_alloc_hash(). 458 */ 459 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 460 BUG_ON(!aalg_desc); 461 462 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 463 crypto_hash_digestsize(tfm)) { 464 printk(KERN_INFO "AH: %s digestsize %u != %hu\n", 465 x->aalg->alg_name, crypto_hash_digestsize(tfm), 466 aalg_desc->uinfo.auth.icv_fullbits/8); 467 goto error; 468 } 469 470 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 471 ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 472 473 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN); 474 475 ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL); 476 if (!ahp->work_icv) 477 goto error; 478 479 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + 480 ahp->icv_trunc_len); 481 switch (x->props.mode) { 482 case XFRM_MODE_BEET: 483 case XFRM_MODE_TRANSPORT: 484 break; 485 case XFRM_MODE_TUNNEL: 486 x->props.header_len += sizeof(struct ipv6hdr); 487 break; 488 default: 489 goto error; 490 } 491 x->data = ahp; 492 493 return 0; 494 495 error: 496 if (ahp) { 497 kfree(ahp->work_icv); 498 crypto_free_hash(ahp->tfm); 499 kfree(ahp); 500 } 501 return -EINVAL; 502 } 503 504 static void ah6_destroy(struct xfrm_state *x) 505 { 506 struct ah_data *ahp = x->data; 507 508 if (!ahp) 509 return; 510 511 kfree(ahp->work_icv); 512 ahp->work_icv = NULL; 513 crypto_free_hash(ahp->tfm); 514 ahp->tfm = NULL; 515 kfree(ahp); 516 } 517 518 static const struct xfrm_type ah6_type = 519 { 520 .description = "AH6", 521 .owner = THIS_MODULE, 522 .proto = IPPROTO_AH, 523 .flags = XFRM_TYPE_REPLAY_PROT, 524 .init_state = ah6_init_state, 525 .destructor = ah6_destroy, 526 .input = ah6_input, 527 .output = ah6_output, 528 .hdr_offset = xfrm6_find_1stfragopt, 529 }; 530 531 static struct inet6_protocol ah6_protocol = { 532 .handler = xfrm6_rcv, 533 .err_handler = ah6_err, 534 .flags = INET6_PROTO_NOPOLICY, 535 }; 536 537 static int __init ah6_init(void) 538 { 539 if (xfrm_register_type(&ah6_type, AF_INET6) < 0) { 540 printk(KERN_INFO "ipv6 ah init: can't add xfrm type\n"); 541 return -EAGAIN; 542 } 543 544 if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) { 545 printk(KERN_INFO "ipv6 ah init: can't add protocol\n"); 546 xfrm_unregister_type(&ah6_type, AF_INET6); 547 return -EAGAIN; 548 } 549 550 return 0; 551 } 552 553 static void __exit ah6_fini(void) 554 { 555 if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0) 556 printk(KERN_INFO "ipv6 ah close: can't remove protocol\n"); 557 558 if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0) 559 printk(KERN_INFO "ipv6 ah close: can't remove xfrm type\n"); 560 561 } 562 563 module_init(ah6_init); 564 module_exit(ah6_fini); 565 566 MODULE_LICENSE("GPL"); 567 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_AH); 568