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 struct esp_data *esp = x->data; 168 169 /* skb is pure payload to encrypt */ 170 aead = esp->aead; 171 alen = crypto_aead_authsize(aead); 172 173 tfclen = 0; 174 if (x->tfcpad) { 175 struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb); 176 u32 padto; 177 178 padto = min(x->tfcpad, esp6_get_mtu(x, dst->child_mtu_cached)); 179 if (skb->len < padto) 180 tfclen = padto - skb->len; 181 } 182 blksize = ALIGN(crypto_aead_blocksize(aead), 4); 183 clen = ALIGN(skb->len + 2 + tfclen, blksize); 184 if (esp->padlen) 185 clen = ALIGN(clen, esp->padlen); 186 plen = clen - skb->len - tfclen; 187 188 err = skb_cow_data(skb, tfclen + plen + alen, &trailer); 189 if (err < 0) 190 goto error; 191 nfrags = err; 192 193 assoclen = sizeof(*esph); 194 sglists = 1; 195 seqhilen = 0; 196 197 if (x->props.flags & XFRM_STATE_ESN) { 198 sglists += 2; 199 seqhilen += sizeof(__be32); 200 assoclen += seqhilen; 201 } 202 203 tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen); 204 if (!tmp) { 205 err = -ENOMEM; 206 goto error; 207 } 208 209 seqhi = esp_tmp_seqhi(tmp); 210 iv = esp_tmp_iv(aead, tmp, seqhilen); 211 req = esp_tmp_givreq(aead, iv); 212 asg = esp_givreq_sg(aead, req); 213 sg = asg + sglists; 214 215 /* Fill padding... */ 216 tail = skb_tail_pointer(trailer); 217 if (tfclen) { 218 memset(tail, 0, tfclen); 219 tail += tfclen; 220 } 221 do { 222 int i; 223 for (i = 0; i < plen - 2; i++) 224 tail[i] = i + 1; 225 } while (0); 226 tail[plen - 2] = plen - 2; 227 tail[plen - 1] = *skb_mac_header(skb); 228 pskb_put(skb, trailer, clen - skb->len + alen); 229 230 skb_push(skb, -skb_network_offset(skb)); 231 esph = ip_esp_hdr(skb); 232 *skb_mac_header(skb) = IPPROTO_ESP; 233 234 esph->spi = x->id.spi; 235 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low); 236 237 sg_init_table(sg, nfrags); 238 skb_to_sgvec(skb, sg, 239 esph->enc_data + crypto_aead_ivsize(aead) - skb->data, 240 clen + alen); 241 242 if ((x->props.flags & XFRM_STATE_ESN)) { 243 sg_init_table(asg, 3); 244 sg_set_buf(asg, &esph->spi, sizeof(__be32)); 245 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi); 246 sg_set_buf(asg + 1, seqhi, seqhilen); 247 sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32)); 248 } else 249 sg_init_one(asg, esph, sizeof(*esph)); 250 251 aead_givcrypt_set_callback(req, 0, esp_output_done, skb); 252 aead_givcrypt_set_crypt(req, sg, sg, clen, iv); 253 aead_givcrypt_set_assoc(req, asg, assoclen); 254 aead_givcrypt_set_giv(req, esph->enc_data, 255 XFRM_SKB_CB(skb)->seq.output.low); 256 257 ESP_SKB_CB(skb)->tmp = tmp; 258 err = crypto_aead_givencrypt(req); 259 if (err == -EINPROGRESS) 260 goto error; 261 262 if (err == -EBUSY) 263 err = NET_XMIT_DROP; 264 265 kfree(tmp); 266 267 error: 268 return err; 269 } 270 271 static int esp_input_done2(struct sk_buff *skb, int err) 272 { 273 struct xfrm_state *x = xfrm_input_state(skb); 274 struct esp_data *esp = x->data; 275 struct crypto_aead *aead = esp->aead; 276 int alen = crypto_aead_authsize(aead); 277 int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead); 278 int elen = skb->len - hlen; 279 int hdr_len = skb_network_header_len(skb); 280 int padlen; 281 u8 nexthdr[2]; 282 283 kfree(ESP_SKB_CB(skb)->tmp); 284 285 if (unlikely(err)) 286 goto out; 287 288 if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2)) 289 BUG(); 290 291 err = -EINVAL; 292 padlen = nexthdr[0]; 293 if (padlen + 2 + alen >= elen) { 294 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage " 295 "padlen=%d, elen=%d\n", padlen + 2, elen - alen); 296 goto out; 297 } 298 299 /* ... check padding bits here. Silly. :-) */ 300 301 pskb_trim(skb, skb->len - alen - padlen - 2); 302 __skb_pull(skb, hlen); 303 if (x->props.mode == XFRM_MODE_TUNNEL) 304 skb_reset_transport_header(skb); 305 else 306 skb_set_transport_header(skb, -hdr_len); 307 308 err = nexthdr[1]; 309 310 /* RFC4303: Drop dummy packets without any error */ 311 if (err == IPPROTO_NONE) 312 err = -EINVAL; 313 314 out: 315 return err; 316 } 317 318 static void esp_input_done(struct crypto_async_request *base, int err) 319 { 320 struct sk_buff *skb = base->data; 321 322 xfrm_input_resume(skb, esp_input_done2(skb, err)); 323 } 324 325 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb) 326 { 327 struct ip_esp_hdr *esph; 328 struct esp_data *esp = x->data; 329 struct crypto_aead *aead = esp->aead; 330 struct aead_request *req; 331 struct sk_buff *trailer; 332 int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead); 333 int nfrags; 334 int assoclen; 335 int sglists; 336 int seqhilen; 337 int ret = 0; 338 void *tmp; 339 __be32 *seqhi; 340 u8 *iv; 341 struct scatterlist *sg; 342 struct scatterlist *asg; 343 344 if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead))) { 345 ret = -EINVAL; 346 goto out; 347 } 348 349 if (elen <= 0) { 350 ret = -EINVAL; 351 goto out; 352 } 353 354 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) { 355 ret = -EINVAL; 356 goto out; 357 } 358 359 ret = -ENOMEM; 360 361 assoclen = sizeof(*esph); 362 sglists = 1; 363 seqhilen = 0; 364 365 if (x->props.flags & XFRM_STATE_ESN) { 366 sglists += 2; 367 seqhilen += sizeof(__be32); 368 assoclen += seqhilen; 369 } 370 371 tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen); 372 if (!tmp) 373 goto out; 374 375 ESP_SKB_CB(skb)->tmp = tmp; 376 seqhi = esp_tmp_seqhi(tmp); 377 iv = esp_tmp_iv(aead, tmp, seqhilen); 378 req = esp_tmp_req(aead, iv); 379 asg = esp_req_sg(aead, req); 380 sg = asg + sglists; 381 382 skb->ip_summed = CHECKSUM_NONE; 383 384 esph = (struct ip_esp_hdr *)skb->data; 385 386 /* Get ivec. This can be wrong, check against another impls. */ 387 iv = esph->enc_data; 388 389 sg_init_table(sg, nfrags); 390 skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen); 391 392 if ((x->props.flags & XFRM_STATE_ESN)) { 393 sg_init_table(asg, 3); 394 sg_set_buf(asg, &esph->spi, sizeof(__be32)); 395 *seqhi = XFRM_SKB_CB(skb)->seq.input.hi; 396 sg_set_buf(asg + 1, seqhi, seqhilen); 397 sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32)); 398 } else 399 sg_init_one(asg, esph, sizeof(*esph)); 400 401 aead_request_set_callback(req, 0, esp_input_done, skb); 402 aead_request_set_crypt(req, sg, sg, elen, iv); 403 aead_request_set_assoc(req, asg, assoclen); 404 405 ret = crypto_aead_decrypt(req); 406 if (ret == -EINPROGRESS) 407 goto out; 408 409 ret = esp_input_done2(skb, ret); 410 411 out: 412 return ret; 413 } 414 415 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu) 416 { 417 struct esp_data *esp = x->data; 418 u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4); 419 u32 align = max_t(u32, blksize, esp->padlen); 420 unsigned int net_adj; 421 422 if (x->props.mode != XFRM_MODE_TUNNEL) 423 net_adj = sizeof(struct ipv6hdr); 424 else 425 net_adj = 0; 426 427 return ((mtu - x->props.header_len - crypto_aead_authsize(esp->aead) - 428 net_adj) & ~(align - 1)) + (net_adj - 2); 429 } 430 431 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 432 u8 type, u8 code, int offset, __be32 info) 433 { 434 struct net *net = dev_net(skb->dev); 435 const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data; 436 struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset); 437 struct xfrm_state *x; 438 439 if (type != ICMPV6_DEST_UNREACH && 440 type != ICMPV6_PKT_TOOBIG && 441 type != NDISC_REDIRECT) 442 return; 443 444 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr, 445 esph->spi, IPPROTO_ESP, AF_INET6); 446 if (!x) 447 return; 448 449 if (type == NDISC_REDIRECT) 450 ip6_redirect(skb, net, 0, 0); 451 else 452 ip6_update_pmtu(skb, net, info, 0, 0); 453 xfrm_state_put(x); 454 } 455 456 static void esp6_destroy(struct xfrm_state *x) 457 { 458 struct esp_data *esp = x->data; 459 460 if (!esp) 461 return; 462 463 crypto_free_aead(esp->aead); 464 kfree(esp); 465 } 466 467 static int esp_init_aead(struct xfrm_state *x) 468 { 469 struct esp_data *esp = x->data; 470 struct crypto_aead *aead; 471 int err; 472 473 aead = crypto_alloc_aead(x->aead->alg_name, 0, 0); 474 err = PTR_ERR(aead); 475 if (IS_ERR(aead)) 476 goto error; 477 478 esp->aead = aead; 479 480 err = crypto_aead_setkey(aead, x->aead->alg_key, 481 (x->aead->alg_key_len + 7) / 8); 482 if (err) 483 goto error; 484 485 err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8); 486 if (err) 487 goto error; 488 489 error: 490 return err; 491 } 492 493 static int esp_init_authenc(struct xfrm_state *x) 494 { 495 struct esp_data *esp = x->data; 496 struct crypto_aead *aead; 497 struct crypto_authenc_key_param *param; 498 struct rtattr *rta; 499 char *key; 500 char *p; 501 char authenc_name[CRYPTO_MAX_ALG_NAME]; 502 unsigned int keylen; 503 int err; 504 505 err = -EINVAL; 506 if (x->ealg == NULL) 507 goto error; 508 509 err = -ENAMETOOLONG; 510 511 if ((x->props.flags & XFRM_STATE_ESN)) { 512 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, 513 "authencesn(%s,%s)", 514 x->aalg ? x->aalg->alg_name : "digest_null", 515 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME) 516 goto error; 517 } else { 518 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, 519 "authenc(%s,%s)", 520 x->aalg ? x->aalg->alg_name : "digest_null", 521 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME) 522 goto error; 523 } 524 525 aead = crypto_alloc_aead(authenc_name, 0, 0); 526 err = PTR_ERR(aead); 527 if (IS_ERR(aead)) 528 goto error; 529 530 esp->aead = aead; 531 532 keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) + 533 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param)); 534 err = -ENOMEM; 535 key = kmalloc(keylen, GFP_KERNEL); 536 if (!key) 537 goto error; 538 539 p = key; 540 rta = (void *)p; 541 rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM; 542 rta->rta_len = RTA_LENGTH(sizeof(*param)); 543 param = RTA_DATA(rta); 544 p += RTA_SPACE(sizeof(*param)); 545 546 if (x->aalg) { 547 struct xfrm_algo_desc *aalg_desc; 548 549 memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8); 550 p += (x->aalg->alg_key_len + 7) / 8; 551 552 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 553 BUG_ON(!aalg_desc); 554 555 err = -EINVAL; 556 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 557 crypto_aead_authsize(aead)) { 558 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 559 x->aalg->alg_name, 560 crypto_aead_authsize(aead), 561 aalg_desc->uinfo.auth.icv_fullbits/8); 562 goto free_key; 563 } 564 565 err = crypto_aead_setauthsize( 566 aead, x->aalg->alg_trunc_len / 8); 567 if (err) 568 goto free_key; 569 } 570 571 param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8); 572 memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8); 573 574 err = crypto_aead_setkey(aead, key, keylen); 575 576 free_key: 577 kfree(key); 578 579 error: 580 return err; 581 } 582 583 static int esp6_init_state(struct xfrm_state *x) 584 { 585 struct esp_data *esp; 586 struct crypto_aead *aead; 587 u32 align; 588 int err; 589 590 if (x->encap) 591 return -EINVAL; 592 593 esp = kzalloc(sizeof(*esp), GFP_KERNEL); 594 if (esp == NULL) 595 return -ENOMEM; 596 597 x->data = esp; 598 599 if (x->aead) 600 err = esp_init_aead(x); 601 else 602 err = esp_init_authenc(x); 603 604 if (err) 605 goto error; 606 607 aead = esp->aead; 608 609 esp->padlen = 0; 610 611 x->props.header_len = sizeof(struct ip_esp_hdr) + 612 crypto_aead_ivsize(aead); 613 switch (x->props.mode) { 614 case XFRM_MODE_BEET: 615 if (x->sel.family != AF_INET6) 616 x->props.header_len += IPV4_BEET_PHMAXLEN + 617 (sizeof(struct ipv6hdr) - sizeof(struct iphdr)); 618 break; 619 case XFRM_MODE_TRANSPORT: 620 break; 621 case XFRM_MODE_TUNNEL: 622 x->props.header_len += sizeof(struct ipv6hdr); 623 break; 624 default: 625 goto error; 626 } 627 628 align = ALIGN(crypto_aead_blocksize(aead), 4); 629 if (esp->padlen) 630 align = max_t(u32, align, esp->padlen); 631 x->props.trailer_len = align + 1 + crypto_aead_authsize(esp->aead); 632 633 error: 634 return err; 635 } 636 637 static const struct xfrm_type esp6_type = 638 { 639 .description = "ESP6", 640 .owner = THIS_MODULE, 641 .proto = IPPROTO_ESP, 642 .flags = XFRM_TYPE_REPLAY_PROT, 643 .init_state = esp6_init_state, 644 .destructor = esp6_destroy, 645 .get_mtu = esp6_get_mtu, 646 .input = esp6_input, 647 .output = esp6_output, 648 .hdr_offset = xfrm6_find_1stfragopt, 649 }; 650 651 static const struct inet6_protocol esp6_protocol = { 652 .handler = xfrm6_rcv, 653 .err_handler = esp6_err, 654 .flags = INET6_PROTO_NOPOLICY, 655 }; 656 657 static int __init esp6_init(void) 658 { 659 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 660 pr_info("%s: can't add xfrm type\n", __func__); 661 return -EAGAIN; 662 } 663 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 664 pr_info("%s: can't add protocol\n", __func__); 665 xfrm_unregister_type(&esp6_type, AF_INET6); 666 return -EAGAIN; 667 } 668 669 return 0; 670 } 671 672 static void __exit esp6_fini(void) 673 { 674 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 675 pr_info("%s: can't remove protocol\n", __func__); 676 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 677 pr_info("%s: can't remove xfrm type\n", __func__); 678 } 679 680 module_init(esp6_init); 681 module_exit(esp6_fini); 682 683 MODULE_LICENSE("GPL"); 684 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP); 685