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 /* 53 * Allocate an AEAD request structure with extra space for SG and IV. 54 * 55 * For alignment considerations the IV is placed at the front, followed 56 * by the request and finally the SG list. 57 * 58 * TODO: Use spare space in skb for this where possible. 59 */ 60 static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags) 61 { 62 unsigned int len; 63 64 len = crypto_aead_ivsize(aead); 65 if (len) { 66 len += crypto_aead_alignmask(aead) & 67 ~(crypto_tfm_ctx_alignment() - 1); 68 len = ALIGN(len, crypto_tfm_ctx_alignment()); 69 } 70 71 len += sizeof(struct aead_givcrypt_request) + crypto_aead_reqsize(aead); 72 len = ALIGN(len, __alignof__(struct scatterlist)); 73 74 len += sizeof(struct scatterlist) * nfrags; 75 76 return kmalloc(len, GFP_ATOMIC); 77 } 78 79 static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp) 80 { 81 return crypto_aead_ivsize(aead) ? 82 PTR_ALIGN((u8 *)tmp, crypto_aead_alignmask(aead) + 1) : tmp; 83 } 84 85 static inline struct aead_givcrypt_request *esp_tmp_givreq( 86 struct crypto_aead *aead, u8 *iv) 87 { 88 struct aead_givcrypt_request *req; 89 90 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead), 91 crypto_tfm_ctx_alignment()); 92 aead_givcrypt_set_tfm(req, aead); 93 return req; 94 } 95 96 static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv) 97 { 98 struct aead_request *req; 99 100 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead), 101 crypto_tfm_ctx_alignment()); 102 aead_request_set_tfm(req, aead); 103 return req; 104 } 105 106 static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead, 107 struct aead_request *req) 108 { 109 return (void *)ALIGN((unsigned long)(req + 1) + 110 crypto_aead_reqsize(aead), 111 __alignof__(struct scatterlist)); 112 } 113 114 static inline struct scatterlist *esp_givreq_sg( 115 struct crypto_aead *aead, struct aead_givcrypt_request *req) 116 { 117 return (void *)ALIGN((unsigned long)(req + 1) + 118 crypto_aead_reqsize(aead), 119 __alignof__(struct scatterlist)); 120 } 121 122 static void esp_output_done(struct crypto_async_request *base, int err) 123 { 124 struct sk_buff *skb = base->data; 125 126 kfree(ESP_SKB_CB(skb)->tmp); 127 xfrm_output_resume(skb, err); 128 } 129 130 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb) 131 { 132 int err; 133 struct ip_esp_hdr *esph; 134 struct crypto_aead *aead; 135 struct aead_givcrypt_request *req; 136 struct scatterlist *sg; 137 struct scatterlist *asg; 138 struct sk_buff *trailer; 139 void *tmp; 140 int blksize; 141 int clen; 142 int alen; 143 int nfrags; 144 u8 *iv; 145 u8 *tail; 146 struct esp_data *esp = x->data; 147 148 /* skb is pure payload to encrypt */ 149 err = -ENOMEM; 150 151 /* Round to block size */ 152 clen = skb->len; 153 154 aead = esp->aead; 155 alen = crypto_aead_authsize(aead); 156 157 blksize = ALIGN(crypto_aead_blocksize(aead), 4); 158 clen = ALIGN(clen + 2, blksize); 159 if (esp->padlen) 160 clen = ALIGN(clen, esp->padlen); 161 162 if ((err = skb_cow_data(skb, clen - skb->len + alen, &trailer)) < 0) 163 goto error; 164 nfrags = err; 165 166 tmp = esp_alloc_tmp(aead, nfrags + 1); 167 if (!tmp) 168 goto error; 169 170 iv = esp_tmp_iv(aead, tmp); 171 req = esp_tmp_givreq(aead, iv); 172 asg = esp_givreq_sg(aead, req); 173 sg = asg + 1; 174 175 /* Fill padding... */ 176 tail = skb_tail_pointer(trailer); 177 do { 178 int i; 179 for (i=0; i<clen-skb->len - 2; i++) 180 tail[i] = i + 1; 181 } while (0); 182 tail[clen-skb->len - 2] = (clen - skb->len) - 2; 183 tail[clen - skb->len - 1] = *skb_mac_header(skb); 184 pskb_put(skb, trailer, clen - skb->len + alen); 185 186 skb_push(skb, -skb_network_offset(skb)); 187 esph = ip_esp_hdr(skb); 188 *skb_mac_header(skb) = IPPROTO_ESP; 189 190 esph->spi = x->id.spi; 191 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq); 192 193 sg_init_table(sg, nfrags); 194 skb_to_sgvec(skb, sg, 195 esph->enc_data + crypto_aead_ivsize(aead) - skb->data, 196 clen + alen); 197 sg_init_one(asg, esph, sizeof(*esph)); 198 199 aead_givcrypt_set_callback(req, 0, esp_output_done, skb); 200 aead_givcrypt_set_crypt(req, sg, sg, clen, iv); 201 aead_givcrypt_set_assoc(req, asg, sizeof(*esph)); 202 aead_givcrypt_set_giv(req, esph->enc_data, XFRM_SKB_CB(skb)->seq); 203 204 ESP_SKB_CB(skb)->tmp = tmp; 205 err = crypto_aead_givencrypt(req); 206 if (err == -EINPROGRESS) 207 goto error; 208 209 if (err == -EBUSY) 210 err = NET_XMIT_DROP; 211 212 kfree(tmp); 213 214 error: 215 return err; 216 } 217 218 static int esp_input_done2(struct sk_buff *skb, int err) 219 { 220 struct xfrm_state *x = xfrm_input_state(skb); 221 struct esp_data *esp = x->data; 222 struct crypto_aead *aead = esp->aead; 223 int alen = crypto_aead_authsize(aead); 224 int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead); 225 int elen = skb->len - hlen; 226 int hdr_len = skb_network_header_len(skb); 227 int padlen; 228 u8 nexthdr[2]; 229 230 kfree(ESP_SKB_CB(skb)->tmp); 231 232 if (unlikely(err)) 233 goto out; 234 235 if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2)) 236 BUG(); 237 238 err = -EINVAL; 239 padlen = nexthdr[0]; 240 if (padlen + 2 + alen >= elen) { 241 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage " 242 "padlen=%d, elen=%d\n", padlen + 2, elen - alen); 243 goto out; 244 } 245 246 /* ... check padding bits here. Silly. :-) */ 247 248 pskb_trim(skb, skb->len - alen - padlen - 2); 249 __skb_pull(skb, hlen); 250 skb_set_transport_header(skb, -hdr_len); 251 252 err = nexthdr[1]; 253 254 /* RFC4303: Drop dummy packets without any error */ 255 if (err == IPPROTO_NONE) 256 err = -EINVAL; 257 258 out: 259 return err; 260 } 261 262 static void esp_input_done(struct crypto_async_request *base, int err) 263 { 264 struct sk_buff *skb = base->data; 265 266 xfrm_input_resume(skb, esp_input_done2(skb, err)); 267 } 268 269 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb) 270 { 271 struct ip_esp_hdr *esph; 272 struct esp_data *esp = x->data; 273 struct crypto_aead *aead = esp->aead; 274 struct aead_request *req; 275 struct sk_buff *trailer; 276 int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead); 277 int nfrags; 278 int ret = 0; 279 void *tmp; 280 u8 *iv; 281 struct scatterlist *sg; 282 struct scatterlist *asg; 283 284 if (!pskb_may_pull(skb, sizeof(*esph))) { 285 ret = -EINVAL; 286 goto out; 287 } 288 289 if (elen <= 0) { 290 ret = -EINVAL; 291 goto out; 292 } 293 294 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) { 295 ret = -EINVAL; 296 goto out; 297 } 298 299 ret = -ENOMEM; 300 tmp = esp_alloc_tmp(aead, nfrags + 1); 301 if (!tmp) 302 goto out; 303 304 ESP_SKB_CB(skb)->tmp = tmp; 305 iv = esp_tmp_iv(aead, tmp); 306 req = esp_tmp_req(aead, iv); 307 asg = esp_req_sg(aead, req); 308 sg = asg + 1; 309 310 skb->ip_summed = CHECKSUM_NONE; 311 312 esph = (struct ip_esp_hdr *)skb->data; 313 314 /* Get ivec. This can be wrong, check against another impls. */ 315 iv = esph->enc_data; 316 317 sg_init_table(sg, nfrags); 318 skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen); 319 sg_init_one(asg, esph, sizeof(*esph)); 320 321 aead_request_set_callback(req, 0, esp_input_done, skb); 322 aead_request_set_crypt(req, sg, sg, elen, iv); 323 aead_request_set_assoc(req, asg, sizeof(*esph)); 324 325 ret = crypto_aead_decrypt(req); 326 if (ret == -EINPROGRESS) 327 goto out; 328 329 ret = esp_input_done2(skb, ret); 330 331 out: 332 return ret; 333 } 334 335 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu) 336 { 337 struct esp_data *esp = x->data; 338 u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4); 339 u32 align = max_t(u32, blksize, esp->padlen); 340 u32 rem; 341 342 mtu -= x->props.header_len + crypto_aead_authsize(esp->aead); 343 rem = mtu & (align - 1); 344 mtu &= ~(align - 1); 345 346 if (x->props.mode != XFRM_MODE_TUNNEL) { 347 u32 padsize = ((blksize - 1) & 7) + 1; 348 mtu -= blksize - padsize; 349 mtu += min_t(u32, blksize - padsize, rem); 350 } 351 352 return mtu - 2; 353 } 354 355 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 356 int type, int code, int offset, __be32 info) 357 { 358 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 359 struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset); 360 struct xfrm_state *x; 361 362 if (type != ICMPV6_DEST_UNREACH && 363 type != ICMPV6_PKT_TOOBIG) 364 return; 365 366 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6); 367 if (!x) 368 return; 369 printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n", 370 ntohl(esph->spi), NIP6(iph->daddr)); 371 xfrm_state_put(x); 372 } 373 374 static void esp6_destroy(struct xfrm_state *x) 375 { 376 struct esp_data *esp = x->data; 377 378 if (!esp) 379 return; 380 381 crypto_free_aead(esp->aead); 382 kfree(esp); 383 } 384 385 static int esp_init_aead(struct xfrm_state *x) 386 { 387 struct esp_data *esp = x->data; 388 struct crypto_aead *aead; 389 int err; 390 391 aead = crypto_alloc_aead(x->aead->alg_name, 0, 0); 392 err = PTR_ERR(aead); 393 if (IS_ERR(aead)) 394 goto error; 395 396 esp->aead = aead; 397 398 err = crypto_aead_setkey(aead, x->aead->alg_key, 399 (x->aead->alg_key_len + 7) / 8); 400 if (err) 401 goto error; 402 403 err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8); 404 if (err) 405 goto error; 406 407 error: 408 return err; 409 } 410 411 static int esp_init_authenc(struct xfrm_state *x) 412 { 413 struct esp_data *esp = x->data; 414 struct crypto_aead *aead; 415 struct crypto_authenc_key_param *param; 416 struct rtattr *rta; 417 char *key; 418 char *p; 419 char authenc_name[CRYPTO_MAX_ALG_NAME]; 420 unsigned int keylen; 421 int err; 422 423 err = -EINVAL; 424 if (x->ealg == NULL) 425 goto error; 426 427 err = -ENAMETOOLONG; 428 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, "authenc(%s,%s)", 429 x->aalg ? x->aalg->alg_name : "digest_null", 430 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME) 431 goto error; 432 433 aead = crypto_alloc_aead(authenc_name, 0, 0); 434 err = PTR_ERR(aead); 435 if (IS_ERR(aead)) 436 goto error; 437 438 esp->aead = aead; 439 440 keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) + 441 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param)); 442 err = -ENOMEM; 443 key = kmalloc(keylen, GFP_KERNEL); 444 if (!key) 445 goto error; 446 447 p = key; 448 rta = (void *)p; 449 rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM; 450 rta->rta_len = RTA_LENGTH(sizeof(*param)); 451 param = RTA_DATA(rta); 452 p += RTA_SPACE(sizeof(*param)); 453 454 if (x->aalg) { 455 struct xfrm_algo_desc *aalg_desc; 456 457 memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8); 458 p += (x->aalg->alg_key_len + 7) / 8; 459 460 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 461 BUG_ON(!aalg_desc); 462 463 err = -EINVAL; 464 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 465 crypto_aead_authsize(aead)) { 466 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 467 x->aalg->alg_name, 468 crypto_aead_authsize(aead), 469 aalg_desc->uinfo.auth.icv_fullbits/8); 470 goto free_key; 471 } 472 473 err = crypto_aead_setauthsize( 474 aead, aalg_desc->uinfo.auth.icv_truncbits / 8); 475 if (err) 476 goto free_key; 477 } 478 479 param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8); 480 memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8); 481 482 err = crypto_aead_setkey(aead, key, keylen); 483 484 free_key: 485 kfree(key); 486 487 error: 488 return err; 489 } 490 491 static int esp6_init_state(struct xfrm_state *x) 492 { 493 struct esp_data *esp; 494 struct crypto_aead *aead; 495 u32 align; 496 int err; 497 498 if (x->encap) 499 return -EINVAL; 500 501 esp = kzalloc(sizeof(*esp), GFP_KERNEL); 502 if (esp == NULL) 503 return -ENOMEM; 504 505 x->data = esp; 506 507 if (x->aead) 508 err = esp_init_aead(x); 509 else 510 err = esp_init_authenc(x); 511 512 if (err) 513 goto error; 514 515 aead = esp->aead; 516 517 esp->padlen = 0; 518 519 x->props.header_len = sizeof(struct ip_esp_hdr) + 520 crypto_aead_ivsize(aead); 521 switch (x->props.mode) { 522 case XFRM_MODE_BEET: 523 case XFRM_MODE_TRANSPORT: 524 break; 525 case XFRM_MODE_TUNNEL: 526 x->props.header_len += sizeof(struct ipv6hdr); 527 break; 528 default: 529 goto error; 530 } 531 532 align = ALIGN(crypto_aead_blocksize(aead), 4); 533 if (esp->padlen) 534 align = max_t(u32, align, esp->padlen); 535 x->props.trailer_len = align + 1 + crypto_aead_authsize(esp->aead); 536 537 error: 538 return err; 539 } 540 541 static const struct xfrm_type esp6_type = 542 { 543 .description = "ESP6", 544 .owner = THIS_MODULE, 545 .proto = IPPROTO_ESP, 546 .flags = XFRM_TYPE_REPLAY_PROT, 547 .init_state = esp6_init_state, 548 .destructor = esp6_destroy, 549 .get_mtu = esp6_get_mtu, 550 .input = esp6_input, 551 .output = esp6_output, 552 .hdr_offset = xfrm6_find_1stfragopt, 553 }; 554 555 static struct inet6_protocol esp6_protocol = { 556 .handler = xfrm6_rcv, 557 .err_handler = esp6_err, 558 .flags = INET6_PROTO_NOPOLICY, 559 }; 560 561 static int __init esp6_init(void) 562 { 563 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 564 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n"); 565 return -EAGAIN; 566 } 567 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 568 printk(KERN_INFO "ipv6 esp init: can't add protocol\n"); 569 xfrm_unregister_type(&esp6_type, AF_INET6); 570 return -EAGAIN; 571 } 572 573 return 0; 574 } 575 576 static void __exit esp6_fini(void) 577 { 578 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 579 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n"); 580 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 581 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n"); 582 } 583 584 module_init(esp6_init); 585 module_exit(esp6_fini); 586 587 MODULE_LICENSE("GPL"); 588 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP); 589