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 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);