net/ipv6/esp6.c

   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);