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.output); 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, 203 XFRM_SKB_CB(skb)->seq.output); 204 205 ESP_SKB_CB(skb)->tmp = tmp; 206 err = crypto_aead_givencrypt(req); 207 if (err == -EINPROGRESS) 208 goto error; 209 210 if (err == -EBUSY) 211 err = NET_XMIT_DROP; 212 213 kfree(tmp); 214 215 error: 216 return err; 217 } 218 219 static int esp_input_done2(struct sk_buff *skb, int err) 220 { 221 struct xfrm_state *x = xfrm_input_state(skb); 222 struct esp_data *esp = x->data; 223 struct crypto_aead *aead = esp->aead; 224 int alen = crypto_aead_authsize(aead); 225 int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead); 226 int elen = skb->len - hlen; 227 int hdr_len = skb_network_header_len(skb); 228 int padlen; 229 u8 nexthdr[2]; 230 231 kfree(ESP_SKB_CB(skb)->tmp); 232 233 if (unlikely(err)) 234 goto out; 235 236 if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2)) 237 BUG(); 238 239 err = -EINVAL; 240 padlen = nexthdr[0]; 241 if (padlen + 2 + alen >= elen) { 242 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage " 243 "padlen=%d, elen=%d\n", padlen + 2, elen - alen); 244 goto out; 245 } 246 247 /* ... check padding bits here. Silly. :-) */ 248 249 pskb_trim(skb, skb->len - alen - padlen - 2); 250 __skb_pull(skb, hlen); 251 skb_set_transport_header(skb, -hdr_len); 252 253 err = nexthdr[1]; 254 255 /* RFC4303: Drop dummy packets without any error */ 256 if (err == IPPROTO_NONE) 257 err = -EINVAL; 258 259 out: 260 return err; 261 } 262 263 static void esp_input_done(struct crypto_async_request *base, int err) 264 { 265 struct sk_buff *skb = base->data; 266 267 xfrm_input_resume(skb, esp_input_done2(skb, err)); 268 } 269 270 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb) 271 { 272 struct ip_esp_hdr *esph; 273 struct esp_data *esp = x->data; 274 struct crypto_aead *aead = esp->aead; 275 struct aead_request *req; 276 struct sk_buff *trailer; 277 int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead); 278 int nfrags; 279 int ret = 0; 280 void *tmp; 281 u8 *iv; 282 struct scatterlist *sg; 283 struct scatterlist *asg; 284 285 if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead))) { 286 ret = -EINVAL; 287 goto out; 288 } 289 290 if (elen <= 0) { 291 ret = -EINVAL; 292 goto out; 293 } 294 295 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) { 296 ret = -EINVAL; 297 goto out; 298 } 299 300 ret = -ENOMEM; 301 tmp = esp_alloc_tmp(aead, nfrags + 1); 302 if (!tmp) 303 goto out; 304 305 ESP_SKB_CB(skb)->tmp = tmp; 306 iv = esp_tmp_iv(aead, tmp); 307 req = esp_tmp_req(aead, iv); 308 asg = esp_req_sg(aead, req); 309 sg = asg + 1; 310 311 skb->ip_summed = CHECKSUM_NONE; 312 313 esph = (struct ip_esp_hdr *)skb->data; 314 315 /* Get ivec. This can be wrong, check against another impls. */ 316 iv = esph->enc_data; 317 318 sg_init_table(sg, nfrags); 319 skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen); 320 sg_init_one(asg, esph, sizeof(*esph)); 321 322 aead_request_set_callback(req, 0, esp_input_done, skb); 323 aead_request_set_crypt(req, sg, sg, elen, iv); 324 aead_request_set_assoc(req, asg, sizeof(*esph)); 325 326 ret = crypto_aead_decrypt(req); 327 if (ret == -EINPROGRESS) 328 goto out; 329 330 ret = esp_input_done2(skb, ret); 331 332 out: 333 return ret; 334 } 335 336 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu) 337 { 338 struct esp_data *esp = x->data; 339 u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4); 340 u32 align = max_t(u32, blksize, esp->padlen); 341 u32 rem; 342 343 mtu -= x->props.header_len + crypto_aead_authsize(esp->aead); 344 rem = mtu & (align - 1); 345 mtu &= ~(align - 1); 346 347 if (x->props.mode != XFRM_MODE_TUNNEL) { 348 u32 padsize = ((blksize - 1) & 7) + 1; 349 mtu -= blksize - padsize; 350 mtu += min_t(u32, blksize - padsize, rem); 351 } 352 353 return mtu - 2; 354 } 355 356 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 357 u8 type, u8 code, int offset, __be32 info) 358 { 359 struct net *net = dev_net(skb->dev); 360 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 361 struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset); 362 struct xfrm_state *x; 363 364 if (type != ICMPV6_DEST_UNREACH && 365 type != ICMPV6_PKT_TOOBIG) 366 return; 367 368 x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6); 369 if (!x) 370 return; 371 printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%pI6\n", 372 ntohl(esph->spi), &iph->daddr); 373 xfrm_state_put(x); 374 } 375 376 static void esp6_destroy(struct xfrm_state *x) 377 { 378 struct esp_data *esp = x->data; 379 380 if (!esp) 381 return; 382 383 crypto_free_aead(esp->aead); 384 kfree(esp); 385 } 386 387 static int esp_init_aead(struct xfrm_state *x) 388 { 389 struct esp_data *esp = x->data; 390 struct crypto_aead *aead; 391 int err; 392 393 aead = crypto_alloc_aead(x->aead->alg_name, 0, 0); 394 err = PTR_ERR(aead); 395 if (IS_ERR(aead)) 396 goto error; 397 398 esp->aead = aead; 399 400 err = crypto_aead_setkey(aead, x->aead->alg_key, 401 (x->aead->alg_key_len + 7) / 8); 402 if (err) 403 goto error; 404 405 err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8); 406 if (err) 407 goto error; 408 409 error: 410 return err; 411 } 412 413 static int esp_init_authenc(struct xfrm_state *x) 414 { 415 struct esp_data *esp = x->data; 416 struct crypto_aead *aead; 417 struct crypto_authenc_key_param *param; 418 struct rtattr *rta; 419 char *key; 420 char *p; 421 char authenc_name[CRYPTO_MAX_ALG_NAME]; 422 unsigned int keylen; 423 int err; 424 425 err = -EINVAL; 426 if (x->ealg == NULL) 427 goto error; 428 429 err = -ENAMETOOLONG; 430 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, "authenc(%s,%s)", 431 x->aalg ? x->aalg->alg_name : "digest_null", 432 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME) 433 goto error; 434 435 aead = crypto_alloc_aead(authenc_name, 0, 0); 436 err = PTR_ERR(aead); 437 if (IS_ERR(aead)) 438 goto error; 439 440 esp->aead = aead; 441 442 keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) + 443 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param)); 444 err = -ENOMEM; 445 key = kmalloc(keylen, GFP_KERNEL); 446 if (!key) 447 goto error; 448 449 p = key; 450 rta = (void *)p; 451 rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM; 452 rta->rta_len = RTA_LENGTH(sizeof(*param)); 453 param = RTA_DATA(rta); 454 p += RTA_SPACE(sizeof(*param)); 455 456 if (x->aalg) { 457 struct xfrm_algo_desc *aalg_desc; 458 459 memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8); 460 p += (x->aalg->alg_key_len + 7) / 8; 461 462 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 463 BUG_ON(!aalg_desc); 464 465 err = -EINVAL; 466 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 467 crypto_aead_authsize(aead)) { 468 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 469 x->aalg->alg_name, 470 crypto_aead_authsize(aead), 471 aalg_desc->uinfo.auth.icv_fullbits/8); 472 goto free_key; 473 } 474 475 err = crypto_aead_setauthsize( 476 aead, x->aalg->alg_trunc_len / 8); 477 if (err) 478 goto free_key; 479 } 480 481 param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8); 482 memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8); 483 484 err = crypto_aead_setkey(aead, key, keylen); 485 486 free_key: 487 kfree(key); 488 489 error: 490 return err; 491 } 492 493 static int esp6_init_state(struct xfrm_state *x) 494 { 495 struct esp_data *esp; 496 struct crypto_aead *aead; 497 u32 align; 498 int err; 499 500 if (x->encap) 501 return -EINVAL; 502 503 esp = kzalloc(sizeof(*esp), GFP_KERNEL); 504 if (esp == NULL) 505 return -ENOMEM; 506 507 x->data = esp; 508 509 if (x->aead) 510 err = esp_init_aead(x); 511 else 512 err = esp_init_authenc(x); 513 514 if (err) 515 goto error; 516 517 aead = esp->aead; 518 519 esp->padlen = 0; 520 521 x->props.header_len = sizeof(struct ip_esp_hdr) + 522 crypto_aead_ivsize(aead); 523 switch (x->props.mode) { 524 case XFRM_MODE_BEET: 525 if (x->sel.family != AF_INET6) 526 x->props.header_len += IPV4_BEET_PHMAXLEN + 527 (sizeof(struct ipv6hdr) - sizeof(struct iphdr)); 528 break; 529 case XFRM_MODE_TRANSPORT: 530 break; 531 case XFRM_MODE_TUNNEL: 532 x->props.header_len += sizeof(struct ipv6hdr); 533 break; 534 default: 535 goto error; 536 } 537 538 align = ALIGN(crypto_aead_blocksize(aead), 4); 539 if (esp->padlen) 540 align = max_t(u32, align, esp->padlen); 541 x->props.trailer_len = align + 1 + crypto_aead_authsize(esp->aead); 542 543 error: 544 return err; 545 } 546 547 static const struct xfrm_type esp6_type = 548 { 549 .description = "ESP6", 550 .owner = THIS_MODULE, 551 .proto = IPPROTO_ESP, 552 .flags = XFRM_TYPE_REPLAY_PROT, 553 .init_state = esp6_init_state, 554 .destructor = esp6_destroy, 555 .get_mtu = esp6_get_mtu, 556 .input = esp6_input, 557 .output = esp6_output, 558 .hdr_offset = xfrm6_find_1stfragopt, 559 }; 560 561 static const struct inet6_protocol esp6_protocol = { 562 .handler = xfrm6_rcv, 563 .err_handler = esp6_err, 564 .flags = INET6_PROTO_NOPOLICY, 565 }; 566 567 static int __init esp6_init(void) 568 { 569 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 570 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n"); 571 return -EAGAIN; 572 } 573 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 574 printk(KERN_INFO "ipv6 esp init: can't add protocol\n"); 575 xfrm_unregister_type(&esp6_type, AF_INET6); 576 return -EAGAIN; 577 } 578 579 return 0; 580 } 581 582 static void __exit esp6_fini(void) 583 { 584 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 585 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n"); 586 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 587 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n"); 588 } 589 590 module_init(esp6_init); 591 module_exit(esp6_fini); 592 593 MODULE_LICENSE("GPL"); 594 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP); 595