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/esp.c 25 */ 26 27 #define pr_fmt(fmt) "IPv6: " fmt 28 29 #include <crypto/aead.h> 30 #include <crypto/authenc.h> 31 #include <linux/err.h> 32 #include <linux/module.h> 33 #include <net/ip.h> 34 #include <net/xfrm.h> 35 #include <net/esp.h> 36 #include <linux/scatterlist.h> 37 #include <linux/kernel.h> 38 #include <linux/pfkeyv2.h> 39 #include <linux/random.h> 40 #include <linux/slab.h> 41 #include <linux/spinlock.h> 42 #include <net/ip6_route.h> 43 #include <net/icmp.h> 44 #include <net/ipv6.h> 45 #include <net/protocol.h> 46 #include <linux/icmpv6.h> 47 48 struct esp_skb_cb { 49 struct xfrm_skb_cb xfrm; 50 void *tmp; 51 }; 52 53 #define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0])) 54 55 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu); 56 57 /* 58 * Allocate an AEAD request structure with extra space for SG and IV. 59 * 60 * For alignment considerations the upper 32 bits of the sequence number are 61 * placed at the front, if present. Followed by the IV, the request and finally 62 * the SG list. 63 * 64 * TODO: Use spare space in skb for this where possible. 65 */ 66 static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags, int seqihlen) 67 { 68 unsigned int len; 69 70 len = seqihlen; 71 72 len += crypto_aead_ivsize(aead); 73 74 if (len) { 75 len += crypto_aead_alignmask(aead) & 76 ~(crypto_tfm_ctx_alignment() - 1); 77 len = ALIGN(len, crypto_tfm_ctx_alignment()); 78 } 79 80 len += sizeof(struct aead_givcrypt_request) + crypto_aead_reqsize(aead); 81 len = ALIGN(len, __alignof__(struct scatterlist)); 82 83 len += sizeof(struct scatterlist) * nfrags; 84 85 return kmalloc(len, GFP_ATOMIC); 86 } 87 88 static inline __be32 *esp_tmp_seqhi(void *tmp) 89 { 90 return PTR_ALIGN((__be32 *)tmp, __alignof__(__be32)); 91 } 92 93 static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp, int seqhilen) 94 { 95 return crypto_aead_ivsize(aead) ? 96 PTR_ALIGN((u8 *)tmp + seqhilen, 97 crypto_aead_alignmask(aead) + 1) : tmp + seqhilen; 98 } 99 100 static inline struct aead_givcrypt_request *esp_tmp_givreq( 101 struct crypto_aead *aead, u8 *iv) 102 { 103 struct aead_givcrypt_request *req; 104 105 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead), 106 crypto_tfm_ctx_alignment()); 107 aead_givcrypt_set_tfm(req, aead); 108 return req; 109 } 110 111 static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv) 112 { 113 struct aead_request *req; 114 115 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead), 116 crypto_tfm_ctx_alignment()); 117 aead_request_set_tfm(req, aead); 118 return req; 119 } 120 121 static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead, 122 struct aead_request *req) 123 { 124 return (void *)ALIGN((unsigned long)(req + 1) + 125 crypto_aead_reqsize(aead), 126 __alignof__(struct scatterlist)); 127 } 128 129 static inline struct scatterlist *esp_givreq_sg( 130 struct crypto_aead *aead, struct aead_givcrypt_request *req) 131 { 132 return (void *)ALIGN((unsigned long)(req + 1) + 133 crypto_aead_reqsize(aead), 134 __alignof__(struct scatterlist)); 135 } 136 137 static void esp_output_done(struct crypto_async_request *base, int err) 138 { 139 struct sk_buff *skb = base->data; 140 141 kfree(ESP_SKB_CB(skb)->tmp); 142 xfrm_output_resume(skb, err); 143 } 144 145 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb) 146 { 147 int err; 148 struct ip_esp_hdr *esph; 149 struct crypto_aead *aead; 150 struct aead_givcrypt_request *req; 151 struct scatterlist *sg; 152 struct scatterlist *asg; 153 struct sk_buff *trailer; 154 void *tmp; 155 int blksize; 156 int clen; 157 int alen; 158 int plen; 159 int tfclen; 160 int nfrags; 161 int assoclen; 162 int sglists; 163 int seqhilen; 164 u8 *iv; 165 u8 *tail; 166 __be32 *seqhi; 167 168 /* skb is pure payload to encrypt */ 169 aead = x->data; 170 alen = crypto_aead_authsize(aead); 171 172 tfclen = 0; 173 if (x->tfcpad) { 174 struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb); 175 u32 padto; 176 177 padto = min(x->tfcpad, esp6_get_mtu(x, dst->child_mtu_cached)); 178 if (skb->len < padto) 179 tfclen = padto - skb->len; 180 } 181 blksize = ALIGN(crypto_aead_blocksize(aead), 4); 182 clen = ALIGN(skb->len + 2 + tfclen, blksize); 183 plen = clen - skb->len - tfclen; 184 185 err = skb_cow_data(skb, tfclen + plen + alen, &trailer); 186 if (err < 0) 187 goto error; 188 nfrags = err; 189 190 assoclen = sizeof(*esph); 191 sglists = 1; 192 seqhilen = 0; 193 194 if (x->props.flags & XFRM_STATE_ESN) { 195 sglists += 2; 196 seqhilen += sizeof(__be32); 197 assoclen += seqhilen; 198 } 199 200 tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen); 201 if (!tmp) { 202 err = -ENOMEM; 203 goto error; 204 } 205 206 seqhi = esp_tmp_seqhi(tmp); 207 iv = esp_tmp_iv(aead, tmp, seqhilen); 208 req = esp_tmp_givreq(aead, iv); 209 asg = esp_givreq_sg(aead, req); 210 sg = asg + sglists; 211 212 /* Fill padding... */ 213 tail = skb_tail_pointer(trailer); 214 if (tfclen) { 215 memset(tail, 0, tfclen); 216 tail += tfclen; 217 } 218 do { 219 int i; 220 for (i = 0; i < plen - 2; i++) 221 tail[i] = i + 1; 222 } while (0); 223 tail[plen - 2] = plen - 2; 224 tail[plen - 1] = *skb_mac_header(skb); 225 pskb_put(skb, trailer, clen - skb->len + alen); 226 227 skb_push(skb, -skb_network_offset(skb)); 228 esph = ip_esp_hdr(skb); 229 *skb_mac_header(skb) = IPPROTO_ESP; 230 231 esph->spi = x->id.spi; 232 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low); 233 234 sg_init_table(sg, nfrags); 235 skb_to_sgvec(skb, sg, 236 esph->enc_data + crypto_aead_ivsize(aead) - skb->data, 237 clen + alen); 238 239 if ((x->props.flags & XFRM_STATE_ESN)) { 240 sg_init_table(asg, 3); 241 sg_set_buf(asg, &esph->spi, sizeof(__be32)); 242 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi); 243 sg_set_buf(asg + 1, seqhi, seqhilen); 244 sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32)); 245 } else 246 sg_init_one(asg, esph, sizeof(*esph)); 247 248 aead_givcrypt_set_callback(req, 0, esp_output_done, skb); 249 aead_givcrypt_set_crypt(req, sg, sg, clen, iv); 250 aead_givcrypt_set_assoc(req, asg, assoclen); 251 aead_givcrypt_set_giv(req, esph->enc_data, 252 XFRM_SKB_CB(skb)->seq.output.low); 253 254 ESP_SKB_CB(skb)->tmp = tmp; 255 err = crypto_aead_givencrypt(req); 256 if (err == -EINPROGRESS) 257 goto error; 258 259 if (err == -EBUSY) 260 err = NET_XMIT_DROP; 261 262 kfree(tmp); 263 264 error: 265 return err; 266 } 267 268 static int esp_input_done2(struct sk_buff *skb, int err) 269 { 270 struct xfrm_state *x = xfrm_input_state(skb); 271 struct crypto_aead *aead = x->data; 272 int alen = crypto_aead_authsize(aead); 273 int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead); 274 int elen = skb->len - hlen; 275 int hdr_len = skb_network_header_len(skb); 276 int padlen; 277 u8 nexthdr[2]; 278 279 kfree(ESP_SKB_CB(skb)->tmp); 280 281 if (unlikely(err)) 282 goto out; 283 284 if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2)) 285 BUG(); 286 287 err = -EINVAL; 288 padlen = nexthdr[0]; 289 if (padlen + 2 + alen >= elen) { 290 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage " 291 "padlen=%d, elen=%d\n", padlen + 2, elen - alen); 292 goto out; 293 } 294 295 /* ... check padding bits here. Silly. :-) */ 296 297 pskb_trim(skb, skb->len - alen - padlen - 2); 298 __skb_pull(skb, hlen); 299 if (x->props.mode == XFRM_MODE_TUNNEL) 300 skb_reset_transport_header(skb); 301 else 302 skb_set_transport_header(skb, -hdr_len); 303 304 err = nexthdr[1]; 305 306 /* RFC4303: Drop dummy packets without any error */ 307 if (err == IPPROTO_NONE) 308 err = -EINVAL; 309 310 out: 311 return err; 312 } 313 314 static void esp_input_done(struct crypto_async_request *base, int err) 315 { 316 struct sk_buff *skb = base->data; 317 318 xfrm_input_resume(skb, esp_input_done2(skb, err)); 319 } 320 321 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb) 322 { 323 struct ip_esp_hdr *esph; 324 struct crypto_aead *aead = x->data; 325 struct aead_request *req; 326 struct sk_buff *trailer; 327 int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead); 328 int nfrags; 329 int assoclen; 330 int sglists; 331 int seqhilen; 332 int ret = 0; 333 void *tmp; 334 __be32 *seqhi; 335 u8 *iv; 336 struct scatterlist *sg; 337 struct scatterlist *asg; 338 339 if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead))) { 340 ret = -EINVAL; 341 goto out; 342 } 343 344 if (elen <= 0) { 345 ret = -EINVAL; 346 goto out; 347 } 348 349 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) { 350 ret = -EINVAL; 351 goto out; 352 } 353 354 ret = -ENOMEM; 355 356 assoclen = sizeof(*esph); 357 sglists = 1; 358 seqhilen = 0; 359 360 if (x->props.flags & XFRM_STATE_ESN) { 361 sglists += 2; 362 seqhilen += sizeof(__be32); 363 assoclen += seqhilen; 364 } 365 366 tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen); 367 if (!tmp) 368 goto out; 369 370 ESP_SKB_CB(skb)->tmp = tmp; 371 seqhi = esp_tmp_seqhi(tmp); 372 iv = esp_tmp_iv(aead, tmp, seqhilen); 373 req = esp_tmp_req(aead, iv); 374 asg = esp_req_sg(aead, req); 375 sg = asg + sglists; 376 377 skb->ip_summed = CHECKSUM_NONE; 378 379 esph = (struct ip_esp_hdr *)skb->data; 380 381 /* Get ivec. This can be wrong, check against another impls. */ 382 iv = esph->enc_data; 383 384 sg_init_table(sg, nfrags); 385 skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen); 386 387 if ((x->props.flags & XFRM_STATE_ESN)) { 388 sg_init_table(asg, 3); 389 sg_set_buf(asg, &esph->spi, sizeof(__be32)); 390 *seqhi = XFRM_SKB_CB(skb)->seq.input.hi; 391 sg_set_buf(asg + 1, seqhi, seqhilen); 392 sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32)); 393 } else 394 sg_init_one(asg, esph, sizeof(*esph)); 395 396 aead_request_set_callback(req, 0, esp_input_done, skb); 397 aead_request_set_crypt(req, sg, sg, elen, iv); 398 aead_request_set_assoc(req, asg, assoclen); 399 400 ret = crypto_aead_decrypt(req); 401 if (ret == -EINPROGRESS) 402 goto out; 403 404 ret = esp_input_done2(skb, ret); 405 406 out: 407 return ret; 408 } 409 410 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu) 411 { 412 struct crypto_aead *aead = x->data; 413 u32 blksize = ALIGN(crypto_aead_blocksize(aead), 4); 414 unsigned int net_adj; 415 416 if (x->props.mode != XFRM_MODE_TUNNEL) 417 net_adj = sizeof(struct ipv6hdr); 418 else 419 net_adj = 0; 420 421 return ((mtu - x->props.header_len - crypto_aead_authsize(aead) - 422 net_adj) & ~(blksize - 1)) + net_adj - 2; 423 } 424 425 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 426 u8 type, u8 code, int offset, __be32 info) 427 { 428 struct net *net = dev_net(skb->dev); 429 const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data; 430 struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset); 431 struct xfrm_state *x; 432 433 if (type != ICMPV6_PKT_TOOBIG && 434 type != NDISC_REDIRECT) 435 return; 436 437 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr, 438 esph->spi, IPPROTO_ESP, AF_INET6); 439 if (!x) 440 return; 441 442 if (type == NDISC_REDIRECT) 443 ip6_redirect(skb, net, skb->dev->ifindex, 0); 444 else 445 ip6_update_pmtu(skb, net, info, 0, 0); 446 xfrm_state_put(x); 447 } 448 449 static void esp6_destroy(struct xfrm_state *x) 450 { 451 struct crypto_aead *aead = x->data; 452 453 if (!aead) 454 return; 455 456 crypto_free_aead(aead); 457 } 458 459 static int esp_init_aead(struct xfrm_state *x) 460 { 461 struct crypto_aead *aead; 462 int err; 463 464 aead = crypto_alloc_aead(x->aead->alg_name, 0, 0); 465 err = PTR_ERR(aead); 466 if (IS_ERR(aead)) 467 goto error; 468 469 x->data = aead; 470 471 err = crypto_aead_setkey(aead, x->aead->alg_key, 472 (x->aead->alg_key_len + 7) / 8); 473 if (err) 474 goto error; 475 476 err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8); 477 if (err) 478 goto error; 479 480 error: 481 return err; 482 } 483 484 static int esp_init_authenc(struct xfrm_state *x) 485 { 486 struct crypto_aead *aead; 487 struct crypto_authenc_key_param *param; 488 struct rtattr *rta; 489 char *key; 490 char *p; 491 char authenc_name[CRYPTO_MAX_ALG_NAME]; 492 unsigned int keylen; 493 int err; 494 495 err = -EINVAL; 496 if (x->ealg == NULL) 497 goto error; 498 499 err = -ENAMETOOLONG; 500 501 if ((x->props.flags & XFRM_STATE_ESN)) { 502 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, 503 "authencesn(%s,%s)", 504 x->aalg ? x->aalg->alg_name : "digest_null", 505 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME) 506 goto error; 507 } else { 508 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, 509 "authenc(%s,%s)", 510 x->aalg ? x->aalg->alg_name : "digest_null", 511 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME) 512 goto error; 513 } 514 515 aead = crypto_alloc_aead(authenc_name, 0, 0); 516 err = PTR_ERR(aead); 517 if (IS_ERR(aead)) 518 goto error; 519 520 x->data = aead; 521 522 keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) + 523 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param)); 524 err = -ENOMEM; 525 key = kmalloc(keylen, GFP_KERNEL); 526 if (!key) 527 goto error; 528 529 p = key; 530 rta = (void *)p; 531 rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM; 532 rta->rta_len = RTA_LENGTH(sizeof(*param)); 533 param = RTA_DATA(rta); 534 p += RTA_SPACE(sizeof(*param)); 535 536 if (x->aalg) { 537 struct xfrm_algo_desc *aalg_desc; 538 539 memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8); 540 p += (x->aalg->alg_key_len + 7) / 8; 541 542 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 543 BUG_ON(!aalg_desc); 544 545 err = -EINVAL; 546 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 547 crypto_aead_authsize(aead)) { 548 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 549 x->aalg->alg_name, 550 crypto_aead_authsize(aead), 551 aalg_desc->uinfo.auth.icv_fullbits/8); 552 goto free_key; 553 } 554 555 err = crypto_aead_setauthsize( 556 aead, x->aalg->alg_trunc_len / 8); 557 if (err) 558 goto free_key; 559 } 560 561 param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8); 562 memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8); 563 564 err = crypto_aead_setkey(aead, key, keylen); 565 566 free_key: 567 kfree(key); 568 569 error: 570 return err; 571 } 572 573 static int esp6_init_state(struct xfrm_state *x) 574 { 575 struct crypto_aead *aead; 576 u32 align; 577 int err; 578 579 if (x->encap) 580 return -EINVAL; 581 582 x->data = NULL; 583 584 if (x->aead) 585 err = esp_init_aead(x); 586 else 587 err = esp_init_authenc(x); 588 589 if (err) 590 goto error; 591 592 aead = x->data; 593 594 x->props.header_len = sizeof(struct ip_esp_hdr) + 595 crypto_aead_ivsize(aead); 596 switch (x->props.mode) { 597 case XFRM_MODE_BEET: 598 if (x->sel.family != AF_INET6) 599 x->props.header_len += IPV4_BEET_PHMAXLEN + 600 (sizeof(struct ipv6hdr) - sizeof(struct iphdr)); 601 break; 602 case XFRM_MODE_TRANSPORT: 603 break; 604 case XFRM_MODE_TUNNEL: 605 x->props.header_len += sizeof(struct ipv6hdr); 606 break; 607 default: 608 goto error; 609 } 610 611 align = ALIGN(crypto_aead_blocksize(aead), 4); 612 x->props.trailer_len = align + 1 + crypto_aead_authsize(aead); 613 614 error: 615 return err; 616 } 617 618 static const struct xfrm_type esp6_type = 619 { 620 .description = "ESP6", 621 .owner = THIS_MODULE, 622 .proto = IPPROTO_ESP, 623 .flags = XFRM_TYPE_REPLAY_PROT, 624 .init_state = esp6_init_state, 625 .destructor = esp6_destroy, 626 .get_mtu = esp6_get_mtu, 627 .input = esp6_input, 628 .output = esp6_output, 629 .hdr_offset = xfrm6_find_1stfragopt, 630 }; 631 632 static const struct inet6_protocol esp6_protocol = { 633 .handler = xfrm6_rcv, 634 .err_handler = esp6_err, 635 .flags = INET6_PROTO_NOPOLICY, 636 }; 637 638 static int __init esp6_init(void) 639 { 640 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 641 pr_info("%s: can't add xfrm type\n", __func__); 642 return -EAGAIN; 643 } 644 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 645 pr_info("%s: can't add protocol\n", __func__); 646 xfrm_unregister_type(&esp6_type, AF_INET6); 647 return -EAGAIN; 648 } 649 650 return 0; 651 } 652 653 static void __exit esp6_fini(void) 654 { 655 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 656 pr_info("%s: can't remove protocol\n", __func__); 657 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 658 pr_info("%s: can't remove xfrm type\n", __func__); 659 } 660 661 module_init(esp6_init); 662 module_exit(esp6_fini); 663 664 MODULE_LICENSE("GPL"); 665 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP); 666