1 #include <crypto/aead.h> 2 #include <crypto/authenc.h> 3 #include <linux/err.h> 4 #include <linux/module.h> 5 #include <net/ip.h> 6 #include <net/xfrm.h> 7 #include <net/esp.h> 8 #include <linux/scatterlist.h> 9 #include <linux/kernel.h> 10 #include <linux/pfkeyv2.h> 11 #include <linux/rtnetlink.h> 12 #include <linux/slab.h> 13 #include <linux/spinlock.h> 14 #include <linux/in6.h> 15 #include <net/icmp.h> 16 #include <net/protocol.h> 17 #include <net/udp.h> 18 19 struct esp_skb_cb { 20 struct xfrm_skb_cb xfrm; 21 void *tmp; 22 }; 23 24 #define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0])) 25 26 /* 27 * Allocate an AEAD request structure with extra space for SG and IV. 28 * 29 * For alignment considerations the IV is placed at the front, followed 30 * by the request and finally the SG list. 31 * 32 * TODO: Use spare space in skb for this where possible. 33 */ 34 static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags) 35 { 36 unsigned int len; 37 38 len = crypto_aead_ivsize(aead); 39 if (len) { 40 len += crypto_aead_alignmask(aead) & 41 ~(crypto_tfm_ctx_alignment() - 1); 42 len = ALIGN(len, crypto_tfm_ctx_alignment()); 43 } 44 45 len += sizeof(struct aead_givcrypt_request) + crypto_aead_reqsize(aead); 46 len = ALIGN(len, __alignof__(struct scatterlist)); 47 48 len += sizeof(struct scatterlist) * nfrags; 49 50 return kmalloc(len, GFP_ATOMIC); 51 } 52 53 static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp) 54 { 55 return crypto_aead_ivsize(aead) ? 56 PTR_ALIGN((u8 *)tmp, crypto_aead_alignmask(aead) + 1) : tmp; 57 } 58 59 static inline struct aead_givcrypt_request *esp_tmp_givreq( 60 struct crypto_aead *aead, u8 *iv) 61 { 62 struct aead_givcrypt_request *req; 63 64 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead), 65 crypto_tfm_ctx_alignment()); 66 aead_givcrypt_set_tfm(req, aead); 67 return req; 68 } 69 70 static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv) 71 { 72 struct aead_request *req; 73 74 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead), 75 crypto_tfm_ctx_alignment()); 76 aead_request_set_tfm(req, aead); 77 return req; 78 } 79 80 static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead, 81 struct aead_request *req) 82 { 83 return (void *)ALIGN((unsigned long)(req + 1) + 84 crypto_aead_reqsize(aead), 85 __alignof__(struct scatterlist)); 86 } 87 88 static inline struct scatterlist *esp_givreq_sg( 89 struct crypto_aead *aead, struct aead_givcrypt_request *req) 90 { 91 return (void *)ALIGN((unsigned long)(req + 1) + 92 crypto_aead_reqsize(aead), 93 __alignof__(struct scatterlist)); 94 } 95 96 static void esp_output_done(struct crypto_async_request *base, int err) 97 { 98 struct sk_buff *skb = base->data; 99 100 kfree(ESP_SKB_CB(skb)->tmp); 101 xfrm_output_resume(skb, err); 102 } 103 104 static int esp_output(struct xfrm_state *x, struct sk_buff *skb) 105 { 106 int err; 107 struct ip_esp_hdr *esph; 108 struct crypto_aead *aead; 109 struct aead_givcrypt_request *req; 110 struct scatterlist *sg; 111 struct scatterlist *asg; 112 struct esp_data *esp; 113 struct sk_buff *trailer; 114 void *tmp; 115 u8 *iv; 116 u8 *tail; 117 int blksize; 118 int clen; 119 int alen; 120 int nfrags; 121 122 /* skb is pure payload to encrypt */ 123 124 err = -ENOMEM; 125 126 /* Round to block size */ 127 clen = skb->len; 128 129 esp = x->data; 130 aead = esp->aead; 131 alen = crypto_aead_authsize(aead); 132 133 blksize = ALIGN(crypto_aead_blocksize(aead), 4); 134 clen = ALIGN(clen + 2, blksize); 135 if (esp->padlen) 136 clen = ALIGN(clen, esp->padlen); 137 138 if ((err = skb_cow_data(skb, clen - skb->len + alen, &trailer)) < 0) 139 goto error; 140 nfrags = err; 141 142 tmp = esp_alloc_tmp(aead, nfrags + 1); 143 if (!tmp) 144 goto error; 145 146 iv = esp_tmp_iv(aead, tmp); 147 req = esp_tmp_givreq(aead, iv); 148 asg = esp_givreq_sg(aead, req); 149 sg = asg + 1; 150 151 /* Fill padding... */ 152 tail = skb_tail_pointer(trailer); 153 do { 154 int i; 155 for (i=0; i<clen-skb->len - 2; i++) 156 tail[i] = i + 1; 157 } while (0); 158 tail[clen - skb->len - 2] = (clen - skb->len) - 2; 159 tail[clen - skb->len - 1] = *skb_mac_header(skb); 160 pskb_put(skb, trailer, clen - skb->len + alen); 161 162 skb_push(skb, -skb_network_offset(skb)); 163 esph = ip_esp_hdr(skb); 164 *skb_mac_header(skb) = IPPROTO_ESP; 165 166 /* this is non-NULL only with UDP Encapsulation */ 167 if (x->encap) { 168 struct xfrm_encap_tmpl *encap = x->encap; 169 struct udphdr *uh; 170 __be32 *udpdata32; 171 __be16 sport, dport; 172 int encap_type; 173 174 spin_lock_bh(&x->lock); 175 sport = encap->encap_sport; 176 dport = encap->encap_dport; 177 encap_type = encap->encap_type; 178 spin_unlock_bh(&x->lock); 179 180 uh = (struct udphdr *)esph; 181 uh->source = sport; 182 uh->dest = dport; 183 uh->len = htons(skb->len - skb_transport_offset(skb)); 184 uh->check = 0; 185 186 switch (encap_type) { 187 default: 188 case UDP_ENCAP_ESPINUDP: 189 esph = (struct ip_esp_hdr *)(uh + 1); 190 break; 191 case UDP_ENCAP_ESPINUDP_NON_IKE: 192 udpdata32 = (__be32 *)(uh + 1); 193 udpdata32[0] = udpdata32[1] = 0; 194 esph = (struct ip_esp_hdr *)(udpdata32 + 2); 195 break; 196 } 197 198 *skb_mac_header(skb) = IPPROTO_UDP; 199 } 200 201 esph->spi = x->id.spi; 202 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output); 203 204 sg_init_table(sg, nfrags); 205 skb_to_sgvec(skb, sg, 206 esph->enc_data + crypto_aead_ivsize(aead) - skb->data, 207 clen + alen); 208 sg_init_one(asg, esph, sizeof(*esph)); 209 210 aead_givcrypt_set_callback(req, 0, esp_output_done, skb); 211 aead_givcrypt_set_crypt(req, sg, sg, clen, iv); 212 aead_givcrypt_set_assoc(req, asg, sizeof(*esph)); 213 aead_givcrypt_set_giv(req, esph->enc_data, 214 XFRM_SKB_CB(skb)->seq.output); 215 216 ESP_SKB_CB(skb)->tmp = tmp; 217 err = crypto_aead_givencrypt(req); 218 if (err == -EINPROGRESS) 219 goto error; 220 221 if (err == -EBUSY) 222 err = NET_XMIT_DROP; 223 224 kfree(tmp); 225 226 error: 227 return err; 228 } 229 230 static int esp_input_done2(struct sk_buff *skb, int err) 231 { 232 struct iphdr *iph; 233 struct xfrm_state *x = xfrm_input_state(skb); 234 struct esp_data *esp = x->data; 235 struct crypto_aead *aead = esp->aead; 236 int alen = crypto_aead_authsize(aead); 237 int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead); 238 int elen = skb->len - hlen; 239 int ihl; 240 u8 nexthdr[2]; 241 int padlen; 242 243 kfree(ESP_SKB_CB(skb)->tmp); 244 245 if (unlikely(err)) 246 goto out; 247 248 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 249 BUG(); 250 251 err = -EINVAL; 252 padlen = nexthdr[0]; 253 if (padlen + 2 + alen >= elen) 254 goto out; 255 256 /* ... check padding bits here. Silly. :-) */ 257 258 iph = ip_hdr(skb); 259 ihl = iph->ihl * 4; 260 261 if (x->encap) { 262 struct xfrm_encap_tmpl *encap = x->encap; 263 struct udphdr *uh = (void *)(skb_network_header(skb) + ihl); 264 265 /* 266 * 1) if the NAT-T peer's IP or port changed then 267 * advertize the change to the keying daemon. 268 * This is an inbound SA, so just compare 269 * SRC ports. 270 */ 271 if (iph->saddr != x->props.saddr.a4 || 272 uh->source != encap->encap_sport) { 273 xfrm_address_t ipaddr; 274 275 ipaddr.a4 = iph->saddr; 276 km_new_mapping(x, &ipaddr, uh->source); 277 278 /* XXX: perhaps add an extra 279 * policy check here, to see 280 * if we should allow or 281 * reject a packet from a 282 * different source 283 * address/port. 284 */ 285 } 286 287 /* 288 * 2) ignore UDP/TCP checksums in case 289 * of NAT-T in Transport Mode, or 290 * perform other post-processing fixes 291 * as per draft-ietf-ipsec-udp-encaps-06, 292 * section 3.1.2 293 */ 294 if (x->props.mode == XFRM_MODE_TRANSPORT) 295 skb->ip_summed = CHECKSUM_UNNECESSARY; 296 } 297 298 pskb_trim(skb, skb->len - alen - padlen - 2); 299 __skb_pull(skb, hlen); 300 skb_set_transport_header(skb, -ihl); 301 302 err = nexthdr[1]; 303 304 /* RFC4303: Drop dummy packets without any error */ 305 if (err == IPPROTO_NONE) 306 err = -EINVAL; 307 308 out: 309 return err; 310 } 311 312 static void esp_input_done(struct crypto_async_request *base, int err) 313 { 314 struct sk_buff *skb = base->data; 315 316 xfrm_input_resume(skb, esp_input_done2(skb, err)); 317 } 318 319 /* 320 * Note: detecting truncated vs. non-truncated authentication data is very 321 * expensive, so we only support truncated data, which is the recommended 322 * and common case. 323 */ 324 static int esp_input(struct xfrm_state *x, struct sk_buff *skb) 325 { 326 struct ip_esp_hdr *esph; 327 struct esp_data *esp = x->data; 328 struct crypto_aead *aead = esp->aead; 329 struct aead_request *req; 330 struct sk_buff *trailer; 331 int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead); 332 int nfrags; 333 void *tmp; 334 u8 *iv; 335 struct scatterlist *sg; 336 struct scatterlist *asg; 337 int err = -EINVAL; 338 339 if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead))) 340 goto out; 341 342 if (elen <= 0) 343 goto out; 344 345 if ((err = skb_cow_data(skb, 0, &trailer)) < 0) 346 goto out; 347 nfrags = err; 348 349 err = -ENOMEM; 350 tmp = esp_alloc_tmp(aead, nfrags + 1); 351 if (!tmp) 352 goto out; 353 354 ESP_SKB_CB(skb)->tmp = tmp; 355 iv = esp_tmp_iv(aead, tmp); 356 req = esp_tmp_req(aead, iv); 357 asg = esp_req_sg(aead, req); 358 sg = asg + 1; 359 360 skb->ip_summed = CHECKSUM_NONE; 361 362 esph = (struct ip_esp_hdr *)skb->data; 363 364 /* Get ivec. This can be wrong, check against another impls. */ 365 iv = esph->enc_data; 366 367 sg_init_table(sg, nfrags); 368 skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen); 369 sg_init_one(asg, esph, sizeof(*esph)); 370 371 aead_request_set_callback(req, 0, esp_input_done, skb); 372 aead_request_set_crypt(req, sg, sg, elen, iv); 373 aead_request_set_assoc(req, asg, sizeof(*esph)); 374 375 err = crypto_aead_decrypt(req); 376 if (err == -EINPROGRESS) 377 goto out; 378 379 err = esp_input_done2(skb, err); 380 381 out: 382 return err; 383 } 384 385 static u32 esp4_get_mtu(struct xfrm_state *x, int mtu) 386 { 387 struct esp_data *esp = x->data; 388 u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4); 389 u32 align = max_t(u32, blksize, esp->padlen); 390 u32 rem; 391 392 mtu -= x->props.header_len + crypto_aead_authsize(esp->aead); 393 rem = mtu & (align - 1); 394 mtu &= ~(align - 1); 395 396 switch (x->props.mode) { 397 case XFRM_MODE_TUNNEL: 398 break; 399 default: 400 case XFRM_MODE_TRANSPORT: 401 /* The worst case */ 402 mtu -= blksize - 4; 403 mtu += min_t(u32, blksize - 4, rem); 404 break; 405 case XFRM_MODE_BEET: 406 /* The worst case. */ 407 mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem); 408 break; 409 } 410 411 return mtu - 2; 412 } 413 414 static void esp4_err(struct sk_buff *skb, u32 info) 415 { 416 struct iphdr *iph = (struct iphdr*)skb->data; 417 struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2)); 418 struct xfrm_state *x; 419 420 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH || 421 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 422 return; 423 424 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET); 425 if (!x) 426 return; 427 NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n", 428 ntohl(esph->spi), ntohl(iph->daddr)); 429 xfrm_state_put(x); 430 } 431 432 static void esp_destroy(struct xfrm_state *x) 433 { 434 struct esp_data *esp = x->data; 435 436 if (!esp) 437 return; 438 439 crypto_free_aead(esp->aead); 440 kfree(esp); 441 } 442 443 static int esp_init_aead(struct xfrm_state *x) 444 { 445 struct esp_data *esp = x->data; 446 struct crypto_aead *aead; 447 int err; 448 449 aead = crypto_alloc_aead(x->aead->alg_name, 0, 0); 450 err = PTR_ERR(aead); 451 if (IS_ERR(aead)) 452 goto error; 453 454 esp->aead = aead; 455 456 err = crypto_aead_setkey(aead, x->aead->alg_key, 457 (x->aead->alg_key_len + 7) / 8); 458 if (err) 459 goto error; 460 461 err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8); 462 if (err) 463 goto error; 464 465 error: 466 return err; 467 } 468 469 static int esp_init_authenc(struct xfrm_state *x) 470 { 471 struct esp_data *esp = x->data; 472 struct crypto_aead *aead; 473 struct crypto_authenc_key_param *param; 474 struct rtattr *rta; 475 char *key; 476 char *p; 477 char authenc_name[CRYPTO_MAX_ALG_NAME]; 478 unsigned int keylen; 479 int err; 480 481 err = -EINVAL; 482 if (x->ealg == NULL) 483 goto error; 484 485 err = -ENAMETOOLONG; 486 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, "authenc(%s,%s)", 487 x->aalg ? x->aalg->alg_name : "digest_null", 488 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME) 489 goto error; 490 491 aead = crypto_alloc_aead(authenc_name, 0, 0); 492 err = PTR_ERR(aead); 493 if (IS_ERR(aead)) 494 goto error; 495 496 esp->aead = aead; 497 498 keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) + 499 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param)); 500 err = -ENOMEM; 501 key = kmalloc(keylen, GFP_KERNEL); 502 if (!key) 503 goto error; 504 505 p = key; 506 rta = (void *)p; 507 rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM; 508 rta->rta_len = RTA_LENGTH(sizeof(*param)); 509 param = RTA_DATA(rta); 510 p += RTA_SPACE(sizeof(*param)); 511 512 if (x->aalg) { 513 struct xfrm_algo_desc *aalg_desc; 514 515 memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8); 516 p += (x->aalg->alg_key_len + 7) / 8; 517 518 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 519 BUG_ON(!aalg_desc); 520 521 err = -EINVAL; 522 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 523 crypto_aead_authsize(aead)) { 524 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 525 x->aalg->alg_name, 526 crypto_aead_authsize(aead), 527 aalg_desc->uinfo.auth.icv_fullbits/8); 528 goto free_key; 529 } 530 531 err = crypto_aead_setauthsize( 532 aead, aalg_desc->uinfo.auth.icv_truncbits / 8); 533 if (err) 534 goto free_key; 535 } 536 537 param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8); 538 memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8); 539 540 err = crypto_aead_setkey(aead, key, keylen); 541 542 free_key: 543 kfree(key); 544 545 error: 546 return err; 547 } 548 549 static int esp_init_state(struct xfrm_state *x) 550 { 551 struct esp_data *esp; 552 struct crypto_aead *aead; 553 u32 align; 554 int err; 555 556 esp = kzalloc(sizeof(*esp), GFP_KERNEL); 557 if (esp == NULL) 558 return -ENOMEM; 559 560 x->data = esp; 561 562 if (x->aead) 563 err = esp_init_aead(x); 564 else 565 err = esp_init_authenc(x); 566 567 if (err) 568 goto error; 569 570 aead = esp->aead; 571 572 esp->padlen = 0; 573 574 x->props.header_len = sizeof(struct ip_esp_hdr) + 575 crypto_aead_ivsize(aead); 576 if (x->props.mode == XFRM_MODE_TUNNEL) 577 x->props.header_len += sizeof(struct iphdr); 578 else if (x->props.mode == XFRM_MODE_BEET && x->sel.family != AF_INET6) 579 x->props.header_len += IPV4_BEET_PHMAXLEN; 580 if (x->encap) { 581 struct xfrm_encap_tmpl *encap = x->encap; 582 583 switch (encap->encap_type) { 584 default: 585 goto error; 586 case UDP_ENCAP_ESPINUDP: 587 x->props.header_len += sizeof(struct udphdr); 588 break; 589 case UDP_ENCAP_ESPINUDP_NON_IKE: 590 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32); 591 break; 592 } 593 } 594 595 align = ALIGN(crypto_aead_blocksize(aead), 4); 596 if (esp->padlen) 597 align = max_t(u32, align, esp->padlen); 598 x->props.trailer_len = align + 1 + crypto_aead_authsize(esp->aead); 599 600 error: 601 return err; 602 } 603 604 static const struct xfrm_type esp_type = 605 { 606 .description = "ESP4", 607 .owner = THIS_MODULE, 608 .proto = IPPROTO_ESP, 609 .flags = XFRM_TYPE_REPLAY_PROT, 610 .init_state = esp_init_state, 611 .destructor = esp_destroy, 612 .get_mtu = esp4_get_mtu, 613 .input = esp_input, 614 .output = esp_output 615 }; 616 617 static struct net_protocol esp4_protocol = { 618 .handler = xfrm4_rcv, 619 .err_handler = esp4_err, 620 .no_policy = 1, 621 }; 622 623 static int __init esp4_init(void) 624 { 625 if (xfrm_register_type(&esp_type, AF_INET) < 0) { 626 printk(KERN_INFO "ip esp init: can't add xfrm type\n"); 627 return -EAGAIN; 628 } 629 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) { 630 printk(KERN_INFO "ip esp init: can't add protocol\n"); 631 xfrm_unregister_type(&esp_type, AF_INET); 632 return -EAGAIN; 633 } 634 return 0; 635 } 636 637 static void __exit esp4_fini(void) 638 { 639 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0) 640 printk(KERN_INFO "ip esp close: can't remove protocol\n"); 641 if (xfrm_unregister_type(&esp_type, AF_INET) < 0) 642 printk(KERN_INFO "ip esp close: can't remove xfrm type\n"); 643 } 644 645 module_init(esp4_init); 646 module_exit(esp4_fini); 647 MODULE_LICENSE("GPL"); 648 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP); 649