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_givcrypt_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_givcrypt_request *esp_tmp_givreq( 100 struct crypto_aead *aead, u8 *iv) 101 { 102 struct aead_givcrypt_request *req; 103 104 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead), 105 crypto_tfm_ctx_alignment()); 106 aead_givcrypt_set_tfm(req, aead); 107 return req; 108 } 109 110 static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv) 111 { 112 struct aead_request *req; 113 114 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead), 115 crypto_tfm_ctx_alignment()); 116 aead_request_set_tfm(req, aead); 117 return req; 118 } 119 120 static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead, 121 struct aead_request *req) 122 { 123 return (void *)ALIGN((unsigned long)(req + 1) + 124 crypto_aead_reqsize(aead), 125 __alignof__(struct scatterlist)); 126 } 127 128 static inline struct scatterlist *esp_givreq_sg( 129 struct crypto_aead *aead, struct aead_givcrypt_request *req) 130 { 131 return (void *)ALIGN((unsigned long)(req + 1) + 132 crypto_aead_reqsize(aead), 133 __alignof__(struct scatterlist)); 134 } 135 136 static void esp_output_done(struct crypto_async_request *base, int err) 137 { 138 struct sk_buff *skb = base->data; 139 140 kfree(ESP_SKB_CB(skb)->tmp); 141 xfrm_output_resume(skb, err); 142 } 143 144 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb) 145 { 146 int err; 147 struct ip_esp_hdr *esph; 148 struct crypto_aead *aead; 149 struct aead_givcrypt_request *req; 150 struct scatterlist *sg; 151 struct scatterlist *asg; 152 struct sk_buff *trailer; 153 void *tmp; 154 int blksize; 155 int clen; 156 int alen; 157 int plen; 158 int tfclen; 159 int nfrags; 160 int assoclen; 161 int sglists; 162 int seqhilen; 163 u8 *iv; 164 u8 *tail; 165 __be32 *seqhi; 166 167 /* skb is pure payload to encrypt */ 168 aead = x->data; 169 alen = crypto_aead_authsize(aead); 170 171 tfclen = 0; 172 if (x->tfcpad) { 173 struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb); 174 u32 padto; 175 176 padto = min(x->tfcpad, esp6_get_mtu(x, dst->child_mtu_cached)); 177 if (skb->len < padto) 178 tfclen = padto - skb->len; 179 } 180 blksize = ALIGN(crypto_aead_blocksize(aead), 4); 181 clen = ALIGN(skb->len + 2 + tfclen, blksize); 182 plen = clen - skb->len - tfclen; 183 184 err = skb_cow_data(skb, tfclen + plen + alen, &trailer); 185 if (err < 0) 186 goto error; 187 nfrags = err; 188 189 assoclen = sizeof(*esph); 190 sglists = 1; 191 seqhilen = 0; 192 193 if (x->props.flags & XFRM_STATE_ESN) { 194 sglists += 2; 195 seqhilen += sizeof(__be32); 196 assoclen += seqhilen; 197 } 198 199 tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen); 200 if (!tmp) { 201 err = -ENOMEM; 202 goto error; 203 } 204 205 seqhi = esp_tmp_seqhi(tmp); 206 iv = esp_tmp_iv(aead, tmp, seqhilen); 207 req = esp_tmp_givreq(aead, iv); 208 asg = esp_givreq_sg(aead, req); 209 sg = asg + sglists; 210 211 /* Fill padding... */ 212 tail = skb_tail_pointer(trailer); 213 if (tfclen) { 214 memset(tail, 0, tfclen); 215 tail += tfclen; 216 } 217 do { 218 int i; 219 for (i = 0; i < plen - 2; i++) 220 tail[i] = i + 1; 221 } while (0); 222 tail[plen - 2] = plen - 2; 223 tail[plen - 1] = *skb_mac_header(skb); 224 pskb_put(skb, trailer, clen - skb->len + alen); 225 226 skb_push(skb, -skb_network_offset(skb)); 227 esph = ip_esp_hdr(skb); 228 *skb_mac_header(skb) = IPPROTO_ESP; 229 230 esph->spi = x->id.spi; 231 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low); 232 233 sg_init_table(sg, nfrags); 234 skb_to_sgvec(skb, sg, 235 esph->enc_data + crypto_aead_ivsize(aead) - skb->data, 236 clen + alen); 237 238 if ((x->props.flags & XFRM_STATE_ESN)) { 239 sg_init_table(asg, 3); 240 sg_set_buf(asg, &esph->spi, sizeof(__be32)); 241 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi); 242 sg_set_buf(asg + 1, seqhi, seqhilen); 243 sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32)); 244 } else 245 sg_init_one(asg, esph, sizeof(*esph)); 246 247 aead_givcrypt_set_callback(req, 0, esp_output_done, skb); 248 aead_givcrypt_set_crypt(req, sg, sg, clen, iv); 249 aead_givcrypt_set_assoc(req, asg, assoclen); 250 aead_givcrypt_set_giv(req, esph->enc_data, 251 XFRM_SKB_CB(skb)->seq.output.low + 252 ((u64)XFRM_SKB_CB(skb)->seq.output.hi << 32)); 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 net_dbg_ratelimited("ipsec esp packet is garbage padlen=%d, elen=%d\n", 291 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 nfrags = skb_cow_data(skb, 0, &trailer); 350 if (nfrags < 0) { 351 ret = -EINVAL; 352 goto out; 353 } 354 355 ret = -ENOMEM; 356 357 assoclen = sizeof(*esph); 358 sglists = 1; 359 seqhilen = 0; 360 361 if (x->props.flags & XFRM_STATE_ESN) { 362 sglists += 2; 363 seqhilen += sizeof(__be32); 364 assoclen += seqhilen; 365 } 366 367 tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen); 368 if (!tmp) 369 goto out; 370 371 ESP_SKB_CB(skb)->tmp = tmp; 372 seqhi = esp_tmp_seqhi(tmp); 373 iv = esp_tmp_iv(aead, tmp, seqhilen); 374 req = esp_tmp_req(aead, iv); 375 asg = esp_req_sg(aead, req); 376 sg = asg + sglists; 377 378 skb->ip_summed = CHECKSUM_NONE; 379 380 esph = (struct ip_esp_hdr *)skb->data; 381 382 /* Get ivec. This can be wrong, check against another impls. */ 383 iv = esph->enc_data; 384 385 sg_init_table(sg, nfrags); 386 skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen); 387 388 if ((x->props.flags & XFRM_STATE_ESN)) { 389 sg_init_table(asg, 3); 390 sg_set_buf(asg, &esph->spi, sizeof(__be32)); 391 *seqhi = XFRM_SKB_CB(skb)->seq.input.hi; 392 sg_set_buf(asg + 1, seqhi, seqhilen); 393 sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32)); 394 } else 395 sg_init_one(asg, esph, sizeof(*esph)); 396 397 aead_request_set_callback(req, 0, esp_input_done, skb); 398 aead_request_set_crypt(req, sg, sg, elen, iv); 399 aead_request_set_assoc(req, asg, assoclen); 400 401 ret = crypto_aead_decrypt(req); 402 if (ret == -EINPROGRESS) 403 goto out; 404 405 ret = esp_input_done2(skb, ret); 406 407 out: 408 return ret; 409 } 410 411 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu) 412 { 413 struct crypto_aead *aead = x->data; 414 u32 blksize = ALIGN(crypto_aead_blocksize(aead), 4); 415 unsigned int net_adj; 416 417 if (x->props.mode != XFRM_MODE_TUNNEL) 418 net_adj = sizeof(struct ipv6hdr); 419 else 420 net_adj = 0; 421 422 return ((mtu - x->props.header_len - crypto_aead_authsize(aead) - 423 net_adj) & ~(blksize - 1)) + net_adj - 2; 424 } 425 426 static int esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 427 u8 type, u8 code, int offset, __be32 info) 428 { 429 struct net *net = dev_net(skb->dev); 430 const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data; 431 struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset); 432 struct xfrm_state *x; 433 434 if (type != ICMPV6_PKT_TOOBIG && 435 type != NDISC_REDIRECT) 436 return 0; 437 438 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr, 439 esph->spi, IPPROTO_ESP, AF_INET6); 440 if (!x) 441 return 0; 442 443 if (type == NDISC_REDIRECT) 444 ip6_redirect(skb, net, skb->dev->ifindex, 0); 445 else 446 ip6_update_pmtu(skb, net, info, 0, 0); 447 xfrm_state_put(x); 448 449 return 0; 450 } 451 452 static void esp6_destroy(struct xfrm_state *x) 453 { 454 struct crypto_aead *aead = x->data; 455 456 if (!aead) 457 return; 458 459 crypto_free_aead(aead); 460 } 461 462 static int esp_init_aead(struct xfrm_state *x) 463 { 464 struct crypto_aead *aead; 465 int err; 466 467 aead = crypto_alloc_aead(x->aead->alg_name, 0, 0); 468 err = PTR_ERR(aead); 469 if (IS_ERR(aead)) 470 goto error; 471 472 x->data = aead; 473 474 err = crypto_aead_setkey(aead, x->aead->alg_key, 475 (x->aead->alg_key_len + 7) / 8); 476 if (err) 477 goto error; 478 479 err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8); 480 if (err) 481 goto error; 482 483 error: 484 return err; 485 } 486 487 static int esp_init_authenc(struct xfrm_state *x) 488 { 489 struct crypto_aead *aead; 490 struct crypto_authenc_key_param *param; 491 struct rtattr *rta; 492 char *key; 493 char *p; 494 char authenc_name[CRYPTO_MAX_ALG_NAME]; 495 unsigned int keylen; 496 int err; 497 498 err = -EINVAL; 499 if (!x->ealg) 500 goto error; 501 502 err = -ENAMETOOLONG; 503 504 if ((x->props.flags & XFRM_STATE_ESN)) { 505 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, 506 "authencesn(%s,%s)", 507 x->aalg ? x->aalg->alg_name : "digest_null", 508 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME) 509 goto error; 510 } else { 511 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, 512 "authenc(%s,%s)", 513 x->aalg ? x->aalg->alg_name : "digest_null", 514 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME) 515 goto error; 516 } 517 518 aead = crypto_alloc_aead(authenc_name, 0, 0); 519 err = PTR_ERR(aead); 520 if (IS_ERR(aead)) 521 goto error; 522 523 x->data = aead; 524 525 keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) + 526 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param)); 527 err = -ENOMEM; 528 key = kmalloc(keylen, GFP_KERNEL); 529 if (!key) 530 goto error; 531 532 p = key; 533 rta = (void *)p; 534 rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM; 535 rta->rta_len = RTA_LENGTH(sizeof(*param)); 536 param = RTA_DATA(rta); 537 p += RTA_SPACE(sizeof(*param)); 538 539 if (x->aalg) { 540 struct xfrm_algo_desc *aalg_desc; 541 542 memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8); 543 p += (x->aalg->alg_key_len + 7) / 8; 544 545 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 546 BUG_ON(!aalg_desc); 547 548 err = -EINVAL; 549 if (aalg_desc->uinfo.auth.icv_fullbits / 8 != 550 crypto_aead_authsize(aead)) { 551 pr_info("ESP: %s digestsize %u != %hu\n", 552 x->aalg->alg_name, 553 crypto_aead_authsize(aead), 554 aalg_desc->uinfo.auth.icv_fullbits / 8); 555 goto free_key; 556 } 557 558 err = crypto_aead_setauthsize( 559 aead, x->aalg->alg_trunc_len / 8); 560 if (err) 561 goto free_key; 562 } 563 564 param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8); 565 memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8); 566 567 err = crypto_aead_setkey(aead, key, keylen); 568 569 free_key: 570 kfree(key); 571 572 error: 573 return err; 574 } 575 576 static int esp6_init_state(struct xfrm_state *x) 577 { 578 struct crypto_aead *aead; 579 u32 align; 580 int err; 581 582 if (x->encap) 583 return -EINVAL; 584 585 x->data = NULL; 586 587 if (x->aead) 588 err = esp_init_aead(x); 589 else 590 err = esp_init_authenc(x); 591 592 if (err) 593 goto error; 594 595 aead = x->data; 596 597 x->props.header_len = sizeof(struct ip_esp_hdr) + 598 crypto_aead_ivsize(aead); 599 switch (x->props.mode) { 600 case XFRM_MODE_BEET: 601 if (x->sel.family != AF_INET6) 602 x->props.header_len += IPV4_BEET_PHMAXLEN + 603 (sizeof(struct ipv6hdr) - sizeof(struct iphdr)); 604 break; 605 case XFRM_MODE_TRANSPORT: 606 break; 607 case XFRM_MODE_TUNNEL: 608 x->props.header_len += sizeof(struct ipv6hdr); 609 break; 610 default: 611 goto error; 612 } 613 614 align = ALIGN(crypto_aead_blocksize(aead), 4); 615 x->props.trailer_len = align + 1 + crypto_aead_authsize(aead); 616 617 error: 618 return err; 619 } 620 621 static int esp6_rcv_cb(struct sk_buff *skb, int err) 622 { 623 return 0; 624 } 625 626 static const struct xfrm_type esp6_type = { 627 .description = "ESP6", 628 .owner = THIS_MODULE, 629 .proto = IPPROTO_ESP, 630 .flags = XFRM_TYPE_REPLAY_PROT, 631 .init_state = esp6_init_state, 632 .destructor = esp6_destroy, 633 .get_mtu = esp6_get_mtu, 634 .input = esp6_input, 635 .output = esp6_output, 636 .hdr_offset = xfrm6_find_1stfragopt, 637 }; 638 639 static struct xfrm6_protocol esp6_protocol = { 640 .handler = xfrm6_rcv, 641 .cb_handler = esp6_rcv_cb, 642 .err_handler = esp6_err, 643 .priority = 0, 644 }; 645 646 static int __init esp6_init(void) 647 { 648 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 649 pr_info("%s: can't add xfrm type\n", __func__); 650 return -EAGAIN; 651 } 652 if (xfrm6_protocol_register(&esp6_protocol, IPPROTO_ESP) < 0) { 653 pr_info("%s: can't add protocol\n", __func__); 654 xfrm_unregister_type(&esp6_type, AF_INET6); 655 return -EAGAIN; 656 } 657 658 return 0; 659 } 660 661 static void __exit esp6_fini(void) 662 { 663 if (xfrm6_protocol_deregister(&esp6_protocol, IPPROTO_ESP) < 0) 664 pr_info("%s: can't remove protocol\n", __func__); 665 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 666 pr_info("%s: can't remove xfrm type\n", __func__); 667 } 668 669 module_init(esp6_init); 670 module_exit(esp6_fini); 671 672 MODULE_LICENSE("GPL"); 673 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP); 674