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, see <http://www.gnu.org/licenses/>. 16 * 17 * Authors 18 * 19 * Mitsuru KANDA @USAGI : IPv6 Support 20 * Kazunori MIYAZAWA @USAGI : 21 * Kunihiro Ishiguro <kunihiro@ipinfusion.com> 22 * 23 * This file is derived from net/ipv4/esp.c 24 */ 25 26 #define pr_fmt(fmt) "IPv6: " fmt 27 28 #include <crypto/aead.h> 29 #include <crypto/authenc.h> 30 #include <linux/err.h> 31 #include <linux/module.h> 32 #include <net/ip.h> 33 #include <net/xfrm.h> 34 #include <net/esp.h> 35 #include <linux/scatterlist.h> 36 #include <linux/kernel.h> 37 #include <linux/pfkeyv2.h> 38 #include <linux/random.h> 39 #include <linux/slab.h> 40 #include <linux/spinlock.h> 41 #include <net/ip6_route.h> 42 #include <net/icmp.h> 43 #include <net/ipv6.h> 44 #include <net/protocol.h> 45 #include <linux/icmpv6.h> 46 47 struct esp_skb_cb { 48 struct xfrm_skb_cb xfrm; 49 void *tmp; 50 }; 51 52 #define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0])) 53 54 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu); 55 56 /* 57 * Allocate an AEAD request structure with extra space for SG and IV. 58 * 59 * For alignment considerations the upper 32 bits of the sequence number are 60 * placed at the front, if present. Followed by the IV, the request and finally 61 * the SG list. 62 * 63 * TODO: Use spare space in skb for this where possible. 64 */ 65 static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags, int seqihlen) 66 { 67 unsigned int len; 68 69 len = seqihlen; 70 71 len += crypto_aead_ivsize(aead); 72 73 if (len) { 74 len += crypto_aead_alignmask(aead) & 75 ~(crypto_tfm_ctx_alignment() - 1); 76 len = ALIGN(len, crypto_tfm_ctx_alignment()); 77 } 78 79 len += sizeof(struct aead_request) + crypto_aead_reqsize(aead); 80 len = ALIGN(len, __alignof__(struct scatterlist)); 81 82 len += sizeof(struct scatterlist) * nfrags; 83 84 return kmalloc(len, GFP_ATOMIC); 85 } 86 87 static inline __be32 *esp_tmp_seqhi(void *tmp) 88 { 89 return PTR_ALIGN((__be32 *)tmp, __alignof__(__be32)); 90 } 91 92 static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp, int seqhilen) 93 { 94 return crypto_aead_ivsize(aead) ? 95 PTR_ALIGN((u8 *)tmp + seqhilen, 96 crypto_aead_alignmask(aead) + 1) : tmp + seqhilen; 97 } 98 99 static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv) 100 { 101 struct aead_request *req; 102 103 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead), 104 crypto_tfm_ctx_alignment()); 105 aead_request_set_tfm(req, aead); 106 return req; 107 } 108 109 static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead, 110 struct aead_request *req) 111 { 112 return (void *)ALIGN((unsigned long)(req + 1) + 113 crypto_aead_reqsize(aead), 114 __alignof__(struct scatterlist)); 115 } 116 117 static void esp_output_done(struct crypto_async_request *base, int err) 118 { 119 struct sk_buff *skb = base->data; 120 121 kfree(ESP_SKB_CB(skb)->tmp); 122 xfrm_output_resume(skb, err); 123 } 124 125 /* Move ESP header back into place. */ 126 static void esp_restore_header(struct sk_buff *skb, unsigned int offset) 127 { 128 struct ip_esp_hdr *esph = (void *)(skb->data + offset); 129 void *tmp = ESP_SKB_CB(skb)->tmp; 130 __be32 *seqhi = esp_tmp_seqhi(tmp); 131 132 esph->seq_no = esph->spi; 133 esph->spi = *seqhi; 134 } 135 136 static void esp_output_restore_header(struct sk_buff *skb) 137 { 138 esp_restore_header(skb, skb_transport_offset(skb) - sizeof(__be32)); 139 } 140 141 static void esp_output_done_esn(struct crypto_async_request *base, int err) 142 { 143 struct sk_buff *skb = base->data; 144 145 esp_output_restore_header(skb); 146 esp_output_done(base, err); 147 } 148 149 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb) 150 { 151 int err; 152 struct ip_esp_hdr *esph; 153 struct crypto_aead *aead; 154 struct aead_request *req; 155 struct scatterlist *sg; 156 struct sk_buff *trailer; 157 void *tmp; 158 int blksize; 159 int clen; 160 int alen; 161 int plen; 162 int ivlen; 163 int tfclen; 164 int nfrags; 165 int assoclen; 166 int seqhilen; 167 u8 *iv; 168 u8 *tail; 169 __be32 *seqhi; 170 __be64 seqno; 171 172 /* skb is pure payload to encrypt */ 173 aead = x->data; 174 alen = crypto_aead_authsize(aead); 175 ivlen = crypto_aead_ivsize(aead); 176 177 tfclen = 0; 178 if (x->tfcpad) { 179 struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb); 180 u32 padto; 181 182 padto = min(x->tfcpad, esp6_get_mtu(x, dst->child_mtu_cached)); 183 if (skb->len < padto) 184 tfclen = padto - skb->len; 185 } 186 blksize = ALIGN(crypto_aead_blocksize(aead), 4); 187 clen = ALIGN(skb->len + 2 + tfclen, blksize); 188 plen = clen - skb->len - tfclen; 189 190 err = skb_cow_data(skb, tfclen + plen + alen, &trailer); 191 if (err < 0) 192 goto error; 193 nfrags = err; 194 195 assoclen = sizeof(*esph); 196 seqhilen = 0; 197 198 if (x->props.flags & XFRM_STATE_ESN) { 199 seqhilen += sizeof(__be32); 200 assoclen += seqhilen; 201 } 202 203 tmp = esp_alloc_tmp(aead, nfrags, 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_req(aead, iv); 212 sg = esp_req_sg(aead, req); 213 214 /* Fill padding... */ 215 tail = skb_tail_pointer(trailer); 216 if (tfclen) { 217 memset(tail, 0, tfclen); 218 tail += tfclen; 219 } 220 do { 221 int i; 222 for (i = 0; i < plen - 2; i++) 223 tail[i] = i + 1; 224 } while (0); 225 tail[plen - 2] = plen - 2; 226 tail[plen - 1] = *skb_mac_header(skb); 227 pskb_put(skb, trailer, clen - skb->len + alen); 228 229 skb_push(skb, -skb_network_offset(skb)); 230 esph = ip_esp_hdr(skb); 231 *skb_mac_header(skb) = IPPROTO_ESP; 232 233 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low); 234 235 aead_request_set_callback(req, 0, esp_output_done, skb); 236 237 /* For ESN we move the header forward by 4 bytes to 238 * accomodate the high bits. We will move it back after 239 * encryption. 240 */ 241 if ((x->props.flags & XFRM_STATE_ESN)) { 242 esph = (void *)(skb_transport_header(skb) - sizeof(__be32)); 243 *seqhi = esph->spi; 244 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.hi); 245 aead_request_set_callback(req, 0, esp_output_done_esn, skb); 246 } 247 248 esph->spi = x->id.spi; 249 250 sg_init_table(sg, nfrags); 251 skb_to_sgvec(skb, sg, 252 (unsigned char *)esph - skb->data, 253 assoclen + ivlen + clen + alen); 254 255 aead_request_set_crypt(req, sg, sg, ivlen + clen, iv); 256 aead_request_set_ad(req, assoclen); 257 258 seqno = cpu_to_be64(XFRM_SKB_CB(skb)->seq.output.low + 259 ((u64)XFRM_SKB_CB(skb)->seq.output.hi << 32)); 260 261 memset(iv, 0, ivlen); 262 memcpy(iv + ivlen - min(ivlen, 8), (u8 *)&seqno + 8 - min(ivlen, 8), 263 min(ivlen, 8)); 264 265 ESP_SKB_CB(skb)->tmp = tmp; 266 err = crypto_aead_encrypt(req); 267 268 switch (err) { 269 case -EINPROGRESS: 270 goto error; 271 272 case -EBUSY: 273 err = NET_XMIT_DROP; 274 break; 275 276 case 0: 277 if ((x->props.flags & XFRM_STATE_ESN)) 278 esp_output_restore_header(skb); 279 } 280 281 kfree(tmp); 282 283 error: 284 return err; 285 } 286 287 static int esp_input_done2(struct sk_buff *skb, int err) 288 { 289 struct xfrm_state *x = xfrm_input_state(skb); 290 struct crypto_aead *aead = x->data; 291 int alen = crypto_aead_authsize(aead); 292 int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead); 293 int elen = skb->len - hlen; 294 int hdr_len = skb_network_header_len(skb); 295 int padlen; 296 u8 nexthdr[2]; 297 298 kfree(ESP_SKB_CB(skb)->tmp); 299 300 if (unlikely(err)) 301 goto out; 302 303 if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2)) 304 BUG(); 305 306 err = -EINVAL; 307 padlen = nexthdr[0]; 308 if (padlen + 2 + alen >= elen) { 309 net_dbg_ratelimited("ipsec esp packet is garbage padlen=%d, elen=%d\n", 310 padlen + 2, elen - alen); 311 goto out; 312 } 313 314 /* ... check padding bits here. Silly. :-) */ 315 316 pskb_trim(skb, skb->len - alen - padlen - 2); 317 __skb_pull(skb, hlen); 318 if (x->props.mode == XFRM_MODE_TUNNEL) 319 skb_reset_transport_header(skb); 320 else 321 skb_set_transport_header(skb, -hdr_len); 322 323 err = nexthdr[1]; 324 325 /* RFC4303: Drop dummy packets without any error */ 326 if (err == IPPROTO_NONE) 327 err = -EINVAL; 328 329 out: 330 return err; 331 } 332 333 static void esp_input_done(struct crypto_async_request *base, int err) 334 { 335 struct sk_buff *skb = base->data; 336 337 xfrm_input_resume(skb, esp_input_done2(skb, err)); 338 } 339 340 static void esp_input_restore_header(struct sk_buff *skb) 341 { 342 esp_restore_header(skb, 0); 343 __skb_pull(skb, 4); 344 } 345 346 static void esp_input_done_esn(struct crypto_async_request *base, int err) 347 { 348 struct sk_buff *skb = base->data; 349 350 esp_input_restore_header(skb); 351 esp_input_done(base, err); 352 } 353 354 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb) 355 { 356 struct ip_esp_hdr *esph; 357 struct crypto_aead *aead = x->data; 358 struct aead_request *req; 359 struct sk_buff *trailer; 360 int ivlen = crypto_aead_ivsize(aead); 361 int elen = skb->len - sizeof(*esph) - ivlen; 362 int nfrags; 363 int assoclen; 364 int seqhilen; 365 int ret = 0; 366 void *tmp; 367 __be32 *seqhi; 368 u8 *iv; 369 struct scatterlist *sg; 370 371 if (!pskb_may_pull(skb, sizeof(*esph) + ivlen)) { 372 ret = -EINVAL; 373 goto out; 374 } 375 376 if (elen <= 0) { 377 ret = -EINVAL; 378 goto out; 379 } 380 381 nfrags = skb_cow_data(skb, 0, &trailer); 382 if (nfrags < 0) { 383 ret = -EINVAL; 384 goto out; 385 } 386 387 ret = -ENOMEM; 388 389 assoclen = sizeof(*esph); 390 seqhilen = 0; 391 392 if (x->props.flags & XFRM_STATE_ESN) { 393 seqhilen += sizeof(__be32); 394 assoclen += seqhilen; 395 } 396 397 tmp = esp_alloc_tmp(aead, nfrags, seqhilen); 398 if (!tmp) 399 goto out; 400 401 ESP_SKB_CB(skb)->tmp = tmp; 402 seqhi = esp_tmp_seqhi(tmp); 403 iv = esp_tmp_iv(aead, tmp, seqhilen); 404 req = esp_tmp_req(aead, iv); 405 sg = esp_req_sg(aead, req); 406 407 skb->ip_summed = CHECKSUM_NONE; 408 409 esph = (struct ip_esp_hdr *)skb->data; 410 411 aead_request_set_callback(req, 0, esp_input_done, skb); 412 413 /* For ESN we move the header forward by 4 bytes to 414 * accomodate the high bits. We will move it back after 415 * decryption. 416 */ 417 if ((x->props.flags & XFRM_STATE_ESN)) { 418 esph = (void *)skb_push(skb, 4); 419 *seqhi = esph->spi; 420 esph->spi = esph->seq_no; 421 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.input.hi); 422 aead_request_set_callback(req, 0, esp_input_done_esn, skb); 423 } 424 425 sg_init_table(sg, nfrags); 426 skb_to_sgvec(skb, sg, 0, skb->len); 427 428 aead_request_set_crypt(req, sg, sg, elen + ivlen, iv); 429 aead_request_set_ad(req, assoclen); 430 431 ret = crypto_aead_decrypt(req); 432 if (ret == -EINPROGRESS) 433 goto out; 434 435 if ((x->props.flags & XFRM_STATE_ESN)) 436 esp_input_restore_header(skb); 437 438 ret = esp_input_done2(skb, ret); 439 440 out: 441 return ret; 442 } 443 444 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu) 445 { 446 struct crypto_aead *aead = x->data; 447 u32 blksize = ALIGN(crypto_aead_blocksize(aead), 4); 448 unsigned int net_adj; 449 450 if (x->props.mode != XFRM_MODE_TUNNEL) 451 net_adj = sizeof(struct ipv6hdr); 452 else 453 net_adj = 0; 454 455 return ((mtu - x->props.header_len - crypto_aead_authsize(aead) - 456 net_adj) & ~(blksize - 1)) + net_adj - 2; 457 } 458 459 static int esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 460 u8 type, u8 code, int offset, __be32 info) 461 { 462 struct net *net = dev_net(skb->dev); 463 const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data; 464 struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset); 465 struct xfrm_state *x; 466 467 if (type != ICMPV6_PKT_TOOBIG && 468 type != NDISC_REDIRECT) 469 return 0; 470 471 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr, 472 esph->spi, IPPROTO_ESP, AF_INET6); 473 if (!x) 474 return 0; 475 476 if (type == NDISC_REDIRECT) 477 ip6_redirect(skb, net, skb->dev->ifindex, 0); 478 else 479 ip6_update_pmtu(skb, net, info, 0, 0); 480 xfrm_state_put(x); 481 482 return 0; 483 } 484 485 static void esp6_destroy(struct xfrm_state *x) 486 { 487 struct crypto_aead *aead = x->data; 488 489 if (!aead) 490 return; 491 492 crypto_free_aead(aead); 493 } 494 495 static int esp_init_aead(struct xfrm_state *x) 496 { 497 char aead_name[CRYPTO_MAX_ALG_NAME]; 498 struct crypto_aead *aead; 499 int err; 500 501 err = -ENAMETOOLONG; 502 if (snprintf(aead_name, CRYPTO_MAX_ALG_NAME, "%s(%s)", 503 x->geniv, x->aead->alg_name) >= CRYPTO_MAX_ALG_NAME) 504 goto error; 505 506 aead = crypto_alloc_aead(aead_name, 0, 0); 507 err = PTR_ERR(aead); 508 if (IS_ERR(aead)) 509 goto error; 510 511 x->data = aead; 512 513 err = crypto_aead_setkey(aead, x->aead->alg_key, 514 (x->aead->alg_key_len + 7) / 8); 515 if (err) 516 goto error; 517 518 err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8); 519 if (err) 520 goto error; 521 522 error: 523 return err; 524 } 525 526 static int esp_init_authenc(struct xfrm_state *x) 527 { 528 struct crypto_aead *aead; 529 struct crypto_authenc_key_param *param; 530 struct rtattr *rta; 531 char *key; 532 char *p; 533 char authenc_name[CRYPTO_MAX_ALG_NAME]; 534 unsigned int keylen; 535 int err; 536 537 err = -EINVAL; 538 if (!x->ealg) 539 goto error; 540 541 err = -ENAMETOOLONG; 542 543 if ((x->props.flags & XFRM_STATE_ESN)) { 544 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, 545 "%s%sauthencesn(%s,%s)%s", 546 x->geniv ?: "", x->geniv ? "(" : "", 547 x->aalg ? x->aalg->alg_name : "digest_null", 548 x->ealg->alg_name, 549 x->geniv ? ")" : "") >= CRYPTO_MAX_ALG_NAME) 550 goto error; 551 } else { 552 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, 553 "%s%sauthenc(%s,%s)%s", 554 x->geniv ?: "", x->geniv ? "(" : "", 555 x->aalg ? x->aalg->alg_name : "digest_null", 556 x->ealg->alg_name, 557 x->geniv ? ")" : "") >= CRYPTO_MAX_ALG_NAME) 558 goto error; 559 } 560 561 aead = crypto_alloc_aead(authenc_name, 0, 0); 562 err = PTR_ERR(aead); 563 if (IS_ERR(aead)) 564 goto error; 565 566 x->data = aead; 567 568 keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) + 569 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param)); 570 err = -ENOMEM; 571 key = kmalloc(keylen, GFP_KERNEL); 572 if (!key) 573 goto error; 574 575 p = key; 576 rta = (void *)p; 577 rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM; 578 rta->rta_len = RTA_LENGTH(sizeof(*param)); 579 param = RTA_DATA(rta); 580 p += RTA_SPACE(sizeof(*param)); 581 582 if (x->aalg) { 583 struct xfrm_algo_desc *aalg_desc; 584 585 memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8); 586 p += (x->aalg->alg_key_len + 7) / 8; 587 588 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 589 BUG_ON(!aalg_desc); 590 591 err = -EINVAL; 592 if (aalg_desc->uinfo.auth.icv_fullbits / 8 != 593 crypto_aead_authsize(aead)) { 594 pr_info("ESP: %s digestsize %u != %hu\n", 595 x->aalg->alg_name, 596 crypto_aead_authsize(aead), 597 aalg_desc->uinfo.auth.icv_fullbits / 8); 598 goto free_key; 599 } 600 601 err = crypto_aead_setauthsize( 602 aead, x->aalg->alg_trunc_len / 8); 603 if (err) 604 goto free_key; 605 } 606 607 param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8); 608 memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8); 609 610 err = crypto_aead_setkey(aead, key, keylen); 611 612 free_key: 613 kfree(key); 614 615 error: 616 return err; 617 } 618 619 static int esp6_init_state(struct xfrm_state *x) 620 { 621 struct crypto_aead *aead; 622 u32 align; 623 int err; 624 625 if (x->encap) 626 return -EINVAL; 627 628 x->data = NULL; 629 630 if (x->aead) 631 err = esp_init_aead(x); 632 else 633 err = esp_init_authenc(x); 634 635 if (err) 636 goto error; 637 638 aead = x->data; 639 640 x->props.header_len = sizeof(struct ip_esp_hdr) + 641 crypto_aead_ivsize(aead); 642 switch (x->props.mode) { 643 case XFRM_MODE_BEET: 644 if (x->sel.family != AF_INET6) 645 x->props.header_len += IPV4_BEET_PHMAXLEN + 646 (sizeof(struct ipv6hdr) - sizeof(struct iphdr)); 647 break; 648 case XFRM_MODE_TRANSPORT: 649 break; 650 case XFRM_MODE_TUNNEL: 651 x->props.header_len += sizeof(struct ipv6hdr); 652 break; 653 default: 654 goto error; 655 } 656 657 align = ALIGN(crypto_aead_blocksize(aead), 4); 658 x->props.trailer_len = align + 1 + crypto_aead_authsize(aead); 659 660 error: 661 return err; 662 } 663 664 static int esp6_rcv_cb(struct sk_buff *skb, int err) 665 { 666 return 0; 667 } 668 669 static const struct xfrm_type esp6_type = { 670 .description = "ESP6", 671 .owner = THIS_MODULE, 672 .proto = IPPROTO_ESP, 673 .flags = XFRM_TYPE_REPLAY_PROT, 674 .init_state = esp6_init_state, 675 .destructor = esp6_destroy, 676 .get_mtu = esp6_get_mtu, 677 .input = esp6_input, 678 .output = esp6_output, 679 .hdr_offset = xfrm6_find_1stfragopt, 680 }; 681 682 static struct xfrm6_protocol esp6_protocol = { 683 .handler = xfrm6_rcv, 684 .cb_handler = esp6_rcv_cb, 685 .err_handler = esp6_err, 686 .priority = 0, 687 }; 688 689 static int __init esp6_init(void) 690 { 691 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 692 pr_info("%s: can't add xfrm type\n", __func__); 693 return -EAGAIN; 694 } 695 if (xfrm6_protocol_register(&esp6_protocol, IPPROTO_ESP) < 0) { 696 pr_info("%s: can't add protocol\n", __func__); 697 xfrm_unregister_type(&esp6_type, AF_INET6); 698 return -EAGAIN; 699 } 700 701 return 0; 702 } 703 704 static void __exit esp6_fini(void) 705 { 706 if (xfrm6_protocol_deregister(&esp6_protocol, IPPROTO_ESP) < 0) 707 pr_info("%s: can't remove protocol\n", __func__); 708 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 709 pr_info("%s: can't remove xfrm type\n", __func__); 710 } 711 712 module_init(esp6_init); 713 module_exit(esp6_fini); 714 715 MODULE_LICENSE("GPL"); 716 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP); 717