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/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 struct esp_data *esp = x->data; 167 168 /* skb is pure payload to encrypt */ 169 err = -ENOMEM; 170 171 aead = esp->aead; 172 alen = crypto_aead_authsize(aead); 173 174 tfclen = 0; 175 if (x->tfcpad) { 176 struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb); 177 u32 padto; 178 179 padto = min(x->tfcpad, esp6_get_mtu(x, dst->child_mtu_cached)); 180 if (skb->len < padto) 181 tfclen = padto - skb->len; 182 } 183 blksize = ALIGN(crypto_aead_blocksize(aead), 4); 184 clen = ALIGN(skb->len + 2 + tfclen, blksize); 185 if (esp->padlen) 186 clen = ALIGN(clen, esp->padlen); 187 plen = clen - skb->len - tfclen; 188 189 err = skb_cow_data(skb, tfclen + plen + alen, &trailer); 190 if (err < 0) 191 goto error; 192 nfrags = err; 193 194 assoclen = sizeof(*esph); 195 sglists = 1; 196 seqhilen = 0; 197 198 if (x->props.flags & XFRM_STATE_ESN) { 199 sglists += 2; 200 seqhilen += sizeof(__be32); 201 assoclen += seqhilen; 202 } 203 204 tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen); 205 if (!tmp) 206 goto error; 207 208 seqhi = esp_tmp_seqhi(tmp); 209 iv = esp_tmp_iv(aead, tmp, seqhilen); 210 req = esp_tmp_givreq(aead, iv); 211 asg = esp_givreq_sg(aead, req); 212 sg = asg + sglists; 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->spi = x->id.spi; 234 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low); 235 236 sg_init_table(sg, nfrags); 237 skb_to_sgvec(skb, sg, 238 esph->enc_data + crypto_aead_ivsize(aead) - skb->data, 239 clen + alen); 240 241 if ((x->props.flags & XFRM_STATE_ESN)) { 242 sg_init_table(asg, 3); 243 sg_set_buf(asg, &esph->spi, sizeof(__be32)); 244 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi); 245 sg_set_buf(asg + 1, seqhi, seqhilen); 246 sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32)); 247 } else 248 sg_init_one(asg, esph, sizeof(*esph)); 249 250 aead_givcrypt_set_callback(req, 0, esp_output_done, skb); 251 aead_givcrypt_set_crypt(req, sg, sg, clen, iv); 252 aead_givcrypt_set_assoc(req, asg, assoclen); 253 aead_givcrypt_set_giv(req, esph->enc_data, 254 XFRM_SKB_CB(skb)->seq.output.low); 255 256 ESP_SKB_CB(skb)->tmp = tmp; 257 err = crypto_aead_givencrypt(req); 258 if (err == -EINPROGRESS) 259 goto error; 260 261 if (err == -EBUSY) 262 err = NET_XMIT_DROP; 263 264 kfree(tmp); 265 266 error: 267 return err; 268 } 269 270 static int esp_input_done2(struct sk_buff *skb, int err) 271 { 272 struct xfrm_state *x = xfrm_input_state(skb); 273 struct esp_data *esp = x->data; 274 struct crypto_aead *aead = esp->aead; 275 int alen = crypto_aead_authsize(aead); 276 int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead); 277 int elen = skb->len - hlen; 278 int hdr_len = skb_network_header_len(skb); 279 int padlen; 280 u8 nexthdr[2]; 281 282 kfree(ESP_SKB_CB(skb)->tmp); 283 284 if (unlikely(err)) 285 goto out; 286 287 if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2)) 288 BUG(); 289 290 err = -EINVAL; 291 padlen = nexthdr[0]; 292 if (padlen + 2 + alen >= elen) { 293 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage " 294 "padlen=%d, elen=%d\n", padlen + 2, elen - alen); 295 goto out; 296 } 297 298 /* ... check padding bits here. Silly. :-) */ 299 300 pskb_trim(skb, skb->len - alen - padlen - 2); 301 __skb_pull(skb, hlen); 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 esp_data *esp = x->data; 325 struct crypto_aead *aead = esp->aead; 326 struct aead_request *req; 327 struct sk_buff *trailer; 328 int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead); 329 int nfrags; 330 int assoclen; 331 int sglists; 332 int seqhilen; 333 int ret = 0; 334 void *tmp; 335 __be32 *seqhi; 336 u8 *iv; 337 struct scatterlist *sg; 338 struct scatterlist *asg; 339 340 if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead))) { 341 ret = -EINVAL; 342 goto out; 343 } 344 345 if (elen <= 0) { 346 ret = -EINVAL; 347 goto out; 348 } 349 350 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 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 esp_data *esp = x->data; 414 u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4); 415 u32 align = max_t(u32, blksize, esp->padlen); 416 unsigned int net_adj; 417 418 if (x->props.mode != XFRM_MODE_TUNNEL) 419 net_adj = sizeof(struct ipv6hdr); 420 else 421 net_adj = 0; 422 423 return ((mtu - x->props.header_len - crypto_aead_authsize(esp->aead) - 424 net_adj) & ~(align - 1)) + (net_adj - 2); 425 } 426 427 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 428 u8 type, u8 code, int offset, __be32 info) 429 { 430 struct net *net = dev_net(skb->dev); 431 const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data; 432 struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset); 433 struct xfrm_state *x; 434 435 if (type != ICMPV6_DEST_UNREACH && 436 type != ICMPV6_PKT_TOOBIG) 437 return; 438 439 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr, 440 esph->spi, IPPROTO_ESP, AF_INET6); 441 if (!x) 442 return; 443 pr_debug("pmtu discovery on SA ESP/%08x/%pI6\n", 444 ntohl(esph->spi), &iph->daddr); 445 xfrm_state_put(x); 446 } 447 448 static void esp6_destroy(struct xfrm_state *x) 449 { 450 struct esp_data *esp = x->data; 451 452 if (!esp) 453 return; 454 455 crypto_free_aead(esp->aead); 456 kfree(esp); 457 } 458 459 static int esp_init_aead(struct xfrm_state *x) 460 { 461 struct esp_data *esp = x->data; 462 struct crypto_aead *aead; 463 int err; 464 465 aead = crypto_alloc_aead(x->aead->alg_name, 0, 0); 466 err = PTR_ERR(aead); 467 if (IS_ERR(aead)) 468 goto error; 469 470 esp->aead = aead; 471 472 err = crypto_aead_setkey(aead, x->aead->alg_key, 473 (x->aead->alg_key_len + 7) / 8); 474 if (err) 475 goto error; 476 477 err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8); 478 if (err) 479 goto error; 480 481 error: 482 return err; 483 } 484 485 static int esp_init_authenc(struct xfrm_state *x) 486 { 487 struct esp_data *esp = x->data; 488 struct crypto_aead *aead; 489 struct crypto_authenc_key_param *param; 490 struct rtattr *rta; 491 char *key; 492 char *p; 493 char authenc_name[CRYPTO_MAX_ALG_NAME]; 494 unsigned int keylen; 495 int err; 496 497 err = -EINVAL; 498 if (x->ealg == NULL) 499 goto error; 500 501 err = -ENAMETOOLONG; 502 503 if ((x->props.flags & XFRM_STATE_ESN)) { 504 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, 505 "authencesn(%s,%s)", 506 x->aalg ? x->aalg->alg_name : "digest_null", 507 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME) 508 goto error; 509 } else { 510 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, 511 "authenc(%s,%s)", 512 x->aalg ? x->aalg->alg_name : "digest_null", 513 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME) 514 goto error; 515 } 516 517 aead = crypto_alloc_aead(authenc_name, 0, 0); 518 err = PTR_ERR(aead); 519 if (IS_ERR(aead)) 520 goto error; 521 522 esp->aead = aead; 523 524 keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) + 525 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param)); 526 err = -ENOMEM; 527 key = kmalloc(keylen, GFP_KERNEL); 528 if (!key) 529 goto error; 530 531 p = key; 532 rta = (void *)p; 533 rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM; 534 rta->rta_len = RTA_LENGTH(sizeof(*param)); 535 param = RTA_DATA(rta); 536 p += RTA_SPACE(sizeof(*param)); 537 538 if (x->aalg) { 539 struct xfrm_algo_desc *aalg_desc; 540 541 memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8); 542 p += (x->aalg->alg_key_len + 7) / 8; 543 544 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 545 BUG_ON(!aalg_desc); 546 547 err = -EINVAL; 548 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 549 crypto_aead_authsize(aead)) { 550 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 551 x->aalg->alg_name, 552 crypto_aead_authsize(aead), 553 aalg_desc->uinfo.auth.icv_fullbits/8); 554 goto free_key; 555 } 556 557 err = crypto_aead_setauthsize( 558 aead, x->aalg->alg_trunc_len / 8); 559 if (err) 560 goto free_key; 561 } 562 563 param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8); 564 memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8); 565 566 err = crypto_aead_setkey(aead, key, keylen); 567 568 free_key: 569 kfree(key); 570 571 error: 572 return err; 573 } 574 575 static int esp6_init_state(struct xfrm_state *x) 576 { 577 struct esp_data *esp; 578 struct crypto_aead *aead; 579 u32 align; 580 int err; 581 582 if (x->encap) 583 return -EINVAL; 584 585 esp = kzalloc(sizeof(*esp), GFP_KERNEL); 586 if (esp == NULL) 587 return -ENOMEM; 588 589 x->data = esp; 590 591 if (x->aead) 592 err = esp_init_aead(x); 593 else 594 err = esp_init_authenc(x); 595 596 if (err) 597 goto error; 598 599 aead = esp->aead; 600 601 esp->padlen = 0; 602 603 x->props.header_len = sizeof(struct ip_esp_hdr) + 604 crypto_aead_ivsize(aead); 605 switch (x->props.mode) { 606 case XFRM_MODE_BEET: 607 if (x->sel.family != AF_INET6) 608 x->props.header_len += IPV4_BEET_PHMAXLEN + 609 (sizeof(struct ipv6hdr) - sizeof(struct iphdr)); 610 break; 611 case XFRM_MODE_TRANSPORT: 612 break; 613 case XFRM_MODE_TUNNEL: 614 x->props.header_len += sizeof(struct ipv6hdr); 615 break; 616 default: 617 goto error; 618 } 619 620 align = ALIGN(crypto_aead_blocksize(aead), 4); 621 if (esp->padlen) 622 align = max_t(u32, align, esp->padlen); 623 x->props.trailer_len = align + 1 + crypto_aead_authsize(esp->aead); 624 625 error: 626 return err; 627 } 628 629 static const struct xfrm_type esp6_type = 630 { 631 .description = "ESP6", 632 .owner = THIS_MODULE, 633 .proto = IPPROTO_ESP, 634 .flags = XFRM_TYPE_REPLAY_PROT, 635 .init_state = esp6_init_state, 636 .destructor = esp6_destroy, 637 .get_mtu = esp6_get_mtu, 638 .input = esp6_input, 639 .output = esp6_output, 640 .hdr_offset = xfrm6_find_1stfragopt, 641 }; 642 643 static const struct inet6_protocol esp6_protocol = { 644 .handler = xfrm6_rcv, 645 .err_handler = esp6_err, 646 .flags = INET6_PROTO_NOPOLICY, 647 }; 648 649 static int __init esp6_init(void) 650 { 651 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 652 pr_info("%s: can't add xfrm type\n", __func__); 653 return -EAGAIN; 654 } 655 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 656 pr_info("%s: can't add protocol\n", __func__); 657 xfrm_unregister_type(&esp6_type, AF_INET6); 658 return -EAGAIN; 659 } 660 661 return 0; 662 } 663 664 static void __exit esp6_fini(void) 665 { 666 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 667 pr_info("%s: can't remove protocol\n", __func__); 668 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 669 pr_info("%s: can't remove xfrm type\n", __func__); 670 } 671 672 module_init(esp6_init); 673 module_exit(esp6_fini); 674 675 MODULE_LICENSE("GPL"); 676 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP); 677