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 #include <crypto/aead.h> 28 #include <crypto/authenc.h> 29 #include <linux/err.h> 30 #include <linux/module.h> 31 #include <net/ip.h> 32 #include <net/xfrm.h> 33 #include <net/esp.h> 34 #include <linux/scatterlist.h> 35 #include <linux/kernel.h> 36 #include <linux/pfkeyv2.h> 37 #include <linux/random.h> 38 #include <linux/slab.h> 39 #include <linux/spinlock.h> 40 #include <net/icmp.h> 41 #include <net/ipv6.h> 42 #include <net/protocol.h> 43 #include <linux/icmpv6.h> 44 45 struct esp_skb_cb { 46 struct xfrm_skb_cb xfrm; 47 void *tmp; 48 }; 49 50 #define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0])) 51 52 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu); 53 54 /* 55 * Allocate an AEAD request structure with extra space for SG and IV. 56 * 57 * For alignment considerations the IV is placed at the front, followed 58 * by the request and finally the SG list. 59 * 60 * TODO: Use spare space in skb for this where possible. 61 */ 62 static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags) 63 { 64 unsigned int len; 65 66 len = crypto_aead_ivsize(aead); 67 if (len) { 68 len += crypto_aead_alignmask(aead) & 69 ~(crypto_tfm_ctx_alignment() - 1); 70 len = ALIGN(len, crypto_tfm_ctx_alignment()); 71 } 72 73 len += sizeof(struct aead_givcrypt_request) + crypto_aead_reqsize(aead); 74 len = ALIGN(len, __alignof__(struct scatterlist)); 75 76 len += sizeof(struct scatterlist) * nfrags; 77 78 return kmalloc(len, GFP_ATOMIC); 79 } 80 81 static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp) 82 { 83 return crypto_aead_ivsize(aead) ? 84 PTR_ALIGN((u8 *)tmp, crypto_aead_alignmask(aead) + 1) : tmp; 85 } 86 87 static inline struct aead_givcrypt_request *esp_tmp_givreq( 88 struct crypto_aead *aead, u8 *iv) 89 { 90 struct aead_givcrypt_request *req; 91 92 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead), 93 crypto_tfm_ctx_alignment()); 94 aead_givcrypt_set_tfm(req, aead); 95 return req; 96 } 97 98 static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv) 99 { 100 struct aead_request *req; 101 102 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead), 103 crypto_tfm_ctx_alignment()); 104 aead_request_set_tfm(req, aead); 105 return req; 106 } 107 108 static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead, 109 struct aead_request *req) 110 { 111 return (void *)ALIGN((unsigned long)(req + 1) + 112 crypto_aead_reqsize(aead), 113 __alignof__(struct scatterlist)); 114 } 115 116 static inline struct scatterlist *esp_givreq_sg( 117 struct crypto_aead *aead, struct aead_givcrypt_request *req) 118 { 119 return (void *)ALIGN((unsigned long)(req + 1) + 120 crypto_aead_reqsize(aead), 121 __alignof__(struct scatterlist)); 122 } 123 124 static void esp_output_done(struct crypto_async_request *base, int err) 125 { 126 struct sk_buff *skb = base->data; 127 128 kfree(ESP_SKB_CB(skb)->tmp); 129 xfrm_output_resume(skb, err); 130 } 131 132 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb) 133 { 134 int err; 135 struct ip_esp_hdr *esph; 136 struct crypto_aead *aead; 137 struct aead_givcrypt_request *req; 138 struct scatterlist *sg; 139 struct scatterlist *asg; 140 struct sk_buff *trailer; 141 void *tmp; 142 int blksize; 143 int clen; 144 int alen; 145 int plen; 146 int tfclen; 147 int nfrags; 148 u8 *iv; 149 u8 *tail; 150 struct esp_data *esp = x->data; 151 152 /* skb is pure payload to encrypt */ 153 err = -ENOMEM; 154 155 aead = esp->aead; 156 alen = crypto_aead_authsize(aead); 157 158 tfclen = 0; 159 if (x->tfcpad) { 160 struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb); 161 u32 padto; 162 163 padto = min(x->tfcpad, esp6_get_mtu(x, dst->child_mtu_cached)); 164 if (skb->len < padto) 165 tfclen = padto - skb->len; 166 } 167 blksize = ALIGN(crypto_aead_blocksize(aead), 4); 168 clen = ALIGN(skb->len + 2 + tfclen, blksize); 169 if (esp->padlen) 170 clen = ALIGN(clen, esp->padlen); 171 plen = clen - skb->len - tfclen; 172 173 err = skb_cow_data(skb, tfclen + plen + alen, &trailer); 174 if (err < 0) 175 goto error; 176 nfrags = err; 177 178 tmp = esp_alloc_tmp(aead, nfrags + 1); 179 if (!tmp) 180 goto error; 181 182 iv = esp_tmp_iv(aead, tmp); 183 req = esp_tmp_givreq(aead, iv); 184 asg = esp_givreq_sg(aead, req); 185 sg = asg + 1; 186 187 /* Fill padding... */ 188 tail = skb_tail_pointer(trailer); 189 if (tfclen) { 190 memset(tail, 0, tfclen); 191 tail += tfclen; 192 } 193 do { 194 int i; 195 for (i = 0; i < plen - 2; i++) 196 tail[i] = i + 1; 197 } while (0); 198 tail[plen - 2] = plen - 2; 199 tail[plen - 1] = *skb_mac_header(skb); 200 pskb_put(skb, trailer, clen - skb->len + alen); 201 202 skb_push(skb, -skb_network_offset(skb)); 203 esph = ip_esp_hdr(skb); 204 *skb_mac_header(skb) = IPPROTO_ESP; 205 206 esph->spi = x->id.spi; 207 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output); 208 209 sg_init_table(sg, nfrags); 210 skb_to_sgvec(skb, sg, 211 esph->enc_data + crypto_aead_ivsize(aead) - skb->data, 212 clen + alen); 213 sg_init_one(asg, esph, sizeof(*esph)); 214 215 aead_givcrypt_set_callback(req, 0, esp_output_done, skb); 216 aead_givcrypt_set_crypt(req, sg, sg, clen, iv); 217 aead_givcrypt_set_assoc(req, asg, sizeof(*esph)); 218 aead_givcrypt_set_giv(req, esph->enc_data, 219 XFRM_SKB_CB(skb)->seq.output); 220 221 ESP_SKB_CB(skb)->tmp = tmp; 222 err = crypto_aead_givencrypt(req); 223 if (err == -EINPROGRESS) 224 goto error; 225 226 if (err == -EBUSY) 227 err = NET_XMIT_DROP; 228 229 kfree(tmp); 230 231 error: 232 return err; 233 } 234 235 static int esp_input_done2(struct sk_buff *skb, int err) 236 { 237 struct xfrm_state *x = xfrm_input_state(skb); 238 struct esp_data *esp = x->data; 239 struct crypto_aead *aead = esp->aead; 240 int alen = crypto_aead_authsize(aead); 241 int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead); 242 int elen = skb->len - hlen; 243 int hdr_len = skb_network_header_len(skb); 244 int padlen; 245 u8 nexthdr[2]; 246 247 kfree(ESP_SKB_CB(skb)->tmp); 248 249 if (unlikely(err)) 250 goto out; 251 252 if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2)) 253 BUG(); 254 255 err = -EINVAL; 256 padlen = nexthdr[0]; 257 if (padlen + 2 + alen >= elen) { 258 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage " 259 "padlen=%d, elen=%d\n", padlen + 2, elen - alen); 260 goto out; 261 } 262 263 /* ... check padding bits here. Silly. :-) */ 264 265 pskb_trim(skb, skb->len - alen - padlen - 2); 266 __skb_pull(skb, hlen); 267 skb_set_transport_header(skb, -hdr_len); 268 269 err = nexthdr[1]; 270 271 /* RFC4303: Drop dummy packets without any error */ 272 if (err == IPPROTO_NONE) 273 err = -EINVAL; 274 275 out: 276 return err; 277 } 278 279 static void esp_input_done(struct crypto_async_request *base, int err) 280 { 281 struct sk_buff *skb = base->data; 282 283 xfrm_input_resume(skb, esp_input_done2(skb, err)); 284 } 285 286 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb) 287 { 288 struct ip_esp_hdr *esph; 289 struct esp_data *esp = x->data; 290 struct crypto_aead *aead = esp->aead; 291 struct aead_request *req; 292 struct sk_buff *trailer; 293 int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead); 294 int nfrags; 295 int ret = 0; 296 void *tmp; 297 u8 *iv; 298 struct scatterlist *sg; 299 struct scatterlist *asg; 300 301 if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead))) { 302 ret = -EINVAL; 303 goto out; 304 } 305 306 if (elen <= 0) { 307 ret = -EINVAL; 308 goto out; 309 } 310 311 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) { 312 ret = -EINVAL; 313 goto out; 314 } 315 316 ret = -ENOMEM; 317 tmp = esp_alloc_tmp(aead, nfrags + 1); 318 if (!tmp) 319 goto out; 320 321 ESP_SKB_CB(skb)->tmp = tmp; 322 iv = esp_tmp_iv(aead, tmp); 323 req = esp_tmp_req(aead, iv); 324 asg = esp_req_sg(aead, req); 325 sg = asg + 1; 326 327 skb->ip_summed = CHECKSUM_NONE; 328 329 esph = (struct ip_esp_hdr *)skb->data; 330 331 /* Get ivec. This can be wrong, check against another impls. */ 332 iv = esph->enc_data; 333 334 sg_init_table(sg, nfrags); 335 skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen); 336 sg_init_one(asg, esph, sizeof(*esph)); 337 338 aead_request_set_callback(req, 0, esp_input_done, skb); 339 aead_request_set_crypt(req, sg, sg, elen, iv); 340 aead_request_set_assoc(req, asg, sizeof(*esph)); 341 342 ret = crypto_aead_decrypt(req); 343 if (ret == -EINPROGRESS) 344 goto out; 345 346 ret = esp_input_done2(skb, ret); 347 348 out: 349 return ret; 350 } 351 352 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu) 353 { 354 struct esp_data *esp = x->data; 355 u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4); 356 u32 align = max_t(u32, blksize, esp->padlen); 357 u32 rem; 358 359 mtu -= x->props.header_len + crypto_aead_authsize(esp->aead); 360 rem = mtu & (align - 1); 361 mtu &= ~(align - 1); 362 363 if (x->props.mode != XFRM_MODE_TUNNEL) { 364 u32 padsize = ((blksize - 1) & 7) + 1; 365 mtu -= blksize - padsize; 366 mtu += min_t(u32, blksize - padsize, rem); 367 } 368 369 return mtu - 2; 370 } 371 372 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 373 u8 type, u8 code, int offset, __be32 info) 374 { 375 struct net *net = dev_net(skb->dev); 376 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 377 struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset); 378 struct xfrm_state *x; 379 380 if (type != ICMPV6_DEST_UNREACH && 381 type != ICMPV6_PKT_TOOBIG) 382 return; 383 384 x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6); 385 if (!x) 386 return; 387 printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%pI6\n", 388 ntohl(esph->spi), &iph->daddr); 389 xfrm_state_put(x); 390 } 391 392 static void esp6_destroy(struct xfrm_state *x) 393 { 394 struct esp_data *esp = x->data; 395 396 if (!esp) 397 return; 398 399 crypto_free_aead(esp->aead); 400 kfree(esp); 401 } 402 403 static int esp_init_aead(struct xfrm_state *x) 404 { 405 struct esp_data *esp = x->data; 406 struct crypto_aead *aead; 407 int err; 408 409 aead = crypto_alloc_aead(x->aead->alg_name, 0, 0); 410 err = PTR_ERR(aead); 411 if (IS_ERR(aead)) 412 goto error; 413 414 esp->aead = aead; 415 416 err = crypto_aead_setkey(aead, x->aead->alg_key, 417 (x->aead->alg_key_len + 7) / 8); 418 if (err) 419 goto error; 420 421 err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8); 422 if (err) 423 goto error; 424 425 error: 426 return err; 427 } 428 429 static int esp_init_authenc(struct xfrm_state *x) 430 { 431 struct esp_data *esp = x->data; 432 struct crypto_aead *aead; 433 struct crypto_authenc_key_param *param; 434 struct rtattr *rta; 435 char *key; 436 char *p; 437 char authenc_name[CRYPTO_MAX_ALG_NAME]; 438 unsigned int keylen; 439 int err; 440 441 err = -EINVAL; 442 if (x->ealg == NULL) 443 goto error; 444 445 err = -ENAMETOOLONG; 446 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, "authenc(%s,%s)", 447 x->aalg ? x->aalg->alg_name : "digest_null", 448 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME) 449 goto error; 450 451 aead = crypto_alloc_aead(authenc_name, 0, 0); 452 err = PTR_ERR(aead); 453 if (IS_ERR(aead)) 454 goto error; 455 456 esp->aead = aead; 457 458 keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) + 459 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param)); 460 err = -ENOMEM; 461 key = kmalloc(keylen, GFP_KERNEL); 462 if (!key) 463 goto error; 464 465 p = key; 466 rta = (void *)p; 467 rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM; 468 rta->rta_len = RTA_LENGTH(sizeof(*param)); 469 param = RTA_DATA(rta); 470 p += RTA_SPACE(sizeof(*param)); 471 472 if (x->aalg) { 473 struct xfrm_algo_desc *aalg_desc; 474 475 memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8); 476 p += (x->aalg->alg_key_len + 7) / 8; 477 478 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 479 BUG_ON(!aalg_desc); 480 481 err = -EINVAL; 482 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 483 crypto_aead_authsize(aead)) { 484 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 485 x->aalg->alg_name, 486 crypto_aead_authsize(aead), 487 aalg_desc->uinfo.auth.icv_fullbits/8); 488 goto free_key; 489 } 490 491 err = crypto_aead_setauthsize( 492 aead, x->aalg->alg_trunc_len / 8); 493 if (err) 494 goto free_key; 495 } 496 497 param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8); 498 memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8); 499 500 err = crypto_aead_setkey(aead, key, keylen); 501 502 free_key: 503 kfree(key); 504 505 error: 506 return err; 507 } 508 509 static int esp6_init_state(struct xfrm_state *x) 510 { 511 struct esp_data *esp; 512 struct crypto_aead *aead; 513 u32 align; 514 int err; 515 516 if (x->encap) 517 return -EINVAL; 518 519 esp = kzalloc(sizeof(*esp), GFP_KERNEL); 520 if (esp == NULL) 521 return -ENOMEM; 522 523 x->data = esp; 524 525 if (x->aead) 526 err = esp_init_aead(x); 527 else 528 err = esp_init_authenc(x); 529 530 if (err) 531 goto error; 532 533 aead = esp->aead; 534 535 esp->padlen = 0; 536 537 x->props.header_len = sizeof(struct ip_esp_hdr) + 538 crypto_aead_ivsize(aead); 539 switch (x->props.mode) { 540 case XFRM_MODE_BEET: 541 if (x->sel.family != AF_INET6) 542 x->props.header_len += IPV4_BEET_PHMAXLEN + 543 (sizeof(struct ipv6hdr) - sizeof(struct iphdr)); 544 break; 545 case XFRM_MODE_TRANSPORT: 546 break; 547 case XFRM_MODE_TUNNEL: 548 x->props.header_len += sizeof(struct ipv6hdr); 549 break; 550 default: 551 goto error; 552 } 553 554 align = ALIGN(crypto_aead_blocksize(aead), 4); 555 if (esp->padlen) 556 align = max_t(u32, align, esp->padlen); 557 x->props.trailer_len = align + 1 + crypto_aead_authsize(esp->aead); 558 559 error: 560 return err; 561 } 562 563 static const struct xfrm_type esp6_type = 564 { 565 .description = "ESP6", 566 .owner = THIS_MODULE, 567 .proto = IPPROTO_ESP, 568 .flags = XFRM_TYPE_REPLAY_PROT, 569 .init_state = esp6_init_state, 570 .destructor = esp6_destroy, 571 .get_mtu = esp6_get_mtu, 572 .input = esp6_input, 573 .output = esp6_output, 574 .hdr_offset = xfrm6_find_1stfragopt, 575 }; 576 577 static const struct inet6_protocol esp6_protocol = { 578 .handler = xfrm6_rcv, 579 .err_handler = esp6_err, 580 .flags = INET6_PROTO_NOPOLICY, 581 }; 582 583 static int __init esp6_init(void) 584 { 585 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 586 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n"); 587 return -EAGAIN; 588 } 589 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 590 printk(KERN_INFO "ipv6 esp init: can't add protocol\n"); 591 xfrm_unregister_type(&esp6_type, AF_INET6); 592 return -EAGAIN; 593 } 594 595 return 0; 596 } 597 598 static void __exit esp6_fini(void) 599 { 600 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 601 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n"); 602 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 603 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n"); 604 } 605 606 module_init(esp6_init); 607 module_exit(esp6_fini); 608 609 MODULE_LICENSE("GPL"); 610 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP); 611