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 <linux/config.h>
  28 #include <linux/module.h>
  29 #include <net/inet_ecn.h>
  30 #include <net/ip.h>
  31 #include <net/xfrm.h>
  32 #include <net/esp.h>
  33 #include <asm/scatterlist.h>
  34 #include <linux/crypto.h>
  35 #include <linux/pfkeyv2.h>
  36 #include <linux/random.h>
  37 #include <net/icmp.h>
  38 #include <net/ipv6.h>
  39 #include <linux/icmpv6.h>
  40
  41 int esp6_output(struct sk_buff **pskb)
  42 {
  43         int err;
  44         int hdr_len = 0;
  45         struct dst_entry *dst = (*pskb)->dst;
  46         struct xfrm_state *x  = dst->xfrm;
  47         struct ipv6hdr *iph = NULL, *top_iph;
  48         struct ipv6_esp_hdr *esph;
  49         struct crypto_tfm *tfm;
  50         struct esp_data *esp;
  51         struct sk_buff *trailer;
  52         int blksize;
  53         int clen;
  54         int alen;
  55         int nfrags;
  56         u8 *prevhdr;
  57         u8 nexthdr = 0;
  58
  59         if ((*pskb)->ip_summed == CHECKSUM_HW) {
  60                 err = skb_checksum_help(pskb, 0);
  61                 if (err)
  62                         goto error_nolock;
  63         }
  64
  65         spin_lock_bh(&x->lock);
  66         err = xfrm_state_check(x, *pskb);
  67         if (err)
  68                 goto error;
  69
  70         if (x->props.mode) {
  71                 err = xfrm6_tunnel_check_size(*pskb);
  72                 if (err)
  73                         goto error;
  74         } else {
  75                 /* Strip IP header in transport mode. Save it. */
  76                 hdr_len = ip6_find_1stfragopt(*pskb, &prevhdr);
  77                 nexthdr = *prevhdr;
  78                 *prevhdr = IPPROTO_ESP;
  79                 iph = kmalloc(hdr_len, GFP_ATOMIC);
  80                 if (!iph) {
  81                         err = -ENOMEM;
  82                         goto error;
  83                 }
  84                 memcpy(iph, (*pskb)->nh.raw, hdr_len);
  85                 __skb_pull(*pskb, hdr_len);
  86         }
  87
  88         /* Now skb is pure payload to encrypt */
  89         err = -ENOMEM;
  90
  91         /* Round to block size */
  92         clen = (*pskb)->len;
  93
  94         esp = x->data;
  95         alen = esp->auth.icv_trunc_len;
  96         tfm = esp->conf.tfm;
  97         blksize = (crypto_tfm_alg_blocksize(tfm) + 3) & ~3;
  98         clen = (clen + 2 + blksize-1)&~(blksize-1);
  99         if (esp->conf.padlen)
 100                 clen = (clen + esp->conf.padlen-1)&~(esp->conf.padlen-1);
 101
 102         if ((nfrags = skb_cow_data(*pskb, clen-(*pskb)->len+alen, &trailer)) < 0) {
 103                 if (!x->props.mode && iph) kfree(iph);
 104                 goto error;
 105         }
 106
 107         /* Fill padding... */
 108         do {
 109                 int i;
 110                 for (i=0; i<clen-(*pskb)->len - 2; i++)
 111                         *(u8*)(trailer->tail + i) = i+1;
 112         } while (0);
 113         *(u8*)(trailer->tail + clen-(*pskb)->len - 2) = (clen - (*pskb)->len)-2;
 114         pskb_put(*pskb, trailer, clen - (*pskb)->len);
 115
 116         if (x->props.mode) {
 117                 iph = (*pskb)->nh.ipv6h;
 118                 top_iph = (struct ipv6hdr*)skb_push(*pskb, x->props.header_len);
 119                 esph = (struct ipv6_esp_hdr*)(top_iph+1);
 120                 *(u8*)(trailer->tail - 1) = IPPROTO_IPV6;
 121                 top_iph->version = 6;
 122                 top_iph->priority = iph->priority;
 123                 top_iph->flow_lbl[0] = iph->flow_lbl[0];
 124                 top_iph->flow_lbl[1] = iph->flow_lbl[1];
 125                 top_iph->flow_lbl[2] = iph->flow_lbl[2];
 126                 if (x->props.flags & XFRM_STATE_NOECN)
 127                         IP6_ECN_clear(top_iph);
 128                 top_iph->nexthdr = IPPROTO_ESP;
 129                 top_iph->payload_len = htons((*pskb)->len + alen - sizeof(struct ipv6hdr));
 130                 top_iph->hop_limit = iph->hop_limit;
 131                 ipv6_addr_copy(&top_iph->saddr,
 132                                (struct in6_addr *)&x->props.saddr);
 133                 ipv6_addr_copy(&top_iph->daddr,
 134                                (struct in6_addr *)&x->id.daddr);
 135         } else {
 136                 esph = (struct ipv6_esp_hdr*)skb_push(*pskb, x->props.header_len);
 137                 (*pskb)->h.raw = (unsigned char*)esph;
 138                 top_iph = (struct ipv6hdr*)skb_push(*pskb, hdr_len);
 139                 memcpy(top_iph, iph, hdr_len);
 140                 kfree(iph);
 141                 top_iph->payload_len = htons((*pskb)->len + alen - sizeof(struct ipv6hdr));
 142                 *(u8*)(trailer->tail - 1) = nexthdr;
 143         }
 144
 145         esph->spi = x->id.spi;
 146         esph->seq_no = htonl(++x->replay.oseq);
 147
 148         if (esp->conf.ivlen)
 149                 crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
 150
 151         do {
 152                 struct scatterlist *sg = &esp->sgbuf[0];
 153
 154                 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
 155                         sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
 156                         if (!sg)
 157                                 goto error;
 158                 }
 159                 skb_to_sgvec(*pskb, sg, esph->enc_data+esp->conf.ivlen-(*pskb)->data, clen);
 160                 crypto_cipher_encrypt(tfm, sg, sg, clen);
 161                 if (unlikely(sg != &esp->sgbuf[0]))
 162                         kfree(sg);
 163         } while (0);
 164
 165         if (esp->conf.ivlen) {
 166                 memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
 167                 crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
 168         }
 169
 170         if (esp->auth.icv_full_len) {
 171                 esp->auth.icv(esp, *pskb, (u8*)esph-(*pskb)->data,
 172                         sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen+clen, trailer->tail);
 173                 pskb_put(*pskb, trailer, alen);
 174         }
 175
 176         (*pskb)->nh.raw = (*pskb)->data;
 177
 178         x->curlft.bytes += (*pskb)->len;
 179         x->curlft.packets++;
 180         spin_unlock_bh(&x->lock);
 181         if (((*pskb)->dst = dst_pop(dst)) == NULL) {
 182                 err = -EHOSTUNREACH;
 183                 goto error_nolock;
 184         }
 185         return NET_XMIT_BYPASS;
 186
 187 error:
 188         spin_unlock_bh(&x->lock);
 189 error_nolock:
 190         kfree_skb(*pskb);
 191         return err;
 192 }
 193
 194 int esp6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
 195 {
 196         struct ipv6hdr *iph;
 197         struct ipv6_esp_hdr *esph;
 198         struct esp_data *esp = x->data;
 199         struct sk_buff *trailer;
 200         int blksize = crypto_tfm_alg_blocksize(esp->conf.tfm);
 201         int alen = esp->auth.icv_trunc_len;
 202         int elen = skb->len - sizeof(struct ipv6_esp_hdr) - esp->conf.ivlen - alen;
 203
 204         int hdr_len = skb->h.raw - skb->nh.raw;
 205         int nfrags;
 206         unsigned char *tmp_hdr = NULL;
 207         int ret = 0;
 208
 209         if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) {
 210                 ret = -EINVAL;
 211                 goto out_nofree;
 212         }
 213
 214         if (elen <= 0 || (elen & (blksize-1))) {
 215                 ret = -EINVAL;
 216                 goto out_nofree;
 217         }
 218
 219         tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
 220         if (!tmp_hdr) {
 221                 ret = -ENOMEM;
 222                 goto out_nofree;
 223         }
 224         memcpy(tmp_hdr, skb->nh.raw, hdr_len);
 225
 226         /* If integrity check is required, do this. */
 227         if (esp->auth.icv_full_len) {
 228                 u8 sum[esp->auth.icv_full_len];
 229                 u8 sum1[alen];
 230
 231                 esp->auth.icv(esp, skb, 0, skb->len-alen, sum);
 232
 233                 if (skb_copy_bits(skb, skb->len-alen, sum1, alen))
 234                         BUG();
 235
 236                 if (unlikely(memcmp(sum, sum1, alen))) {
 237                         x->stats.integrity_failed++;
 238                         ret = -EINVAL;
 239                         goto out;
 240                 }
 241         }
 242
 243         if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
 244                 ret = -EINVAL;
 245                 goto out;
 246         }
 247
 248         skb->ip_summed = CHECKSUM_NONE;
 249
 250         esph = (struct ipv6_esp_hdr*)skb->data;
 251         iph = skb->nh.ipv6h;
 252
 253         /* Get ivec. This can be wrong, check against another impls. */
 254         if (esp->conf.ivlen)
 255                 crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm));
 256
 257         {
 258                 u8 nexthdr[2];
 259                 struct scatterlist *sg = &esp->sgbuf[0];
 260                 u8 padlen;
 261                 u8 *prevhdr;
 262
 263                 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
 264                         sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
 265                         if (!sg) {
 266                                 ret = -ENOMEM;
 267                                 goto out;
 268                         }
 269                 }
 270                 skb_to_sgvec(skb, sg, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen, elen);
 271                 crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen);
 272                 if (unlikely(sg != &esp->sgbuf[0]))
 273                         kfree(sg);
 274
 275                 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
 276                         BUG();
 277
 278                 padlen = nexthdr[0];
 279                 if (padlen+2 >= elen) {
 280                         LIMIT_NETDEBUG(
 281                                 printk(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen));
 282                         ret = -EINVAL;
 283                         goto out;
 284                 }
 285                 /* ... check padding bits here. Silly. :-) */
 286
 287                 pskb_trim(skb, skb->len - alen - padlen - 2);
 288                 skb->h.raw = skb_pull(skb, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen);
 289                 skb->nh.raw += sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen;
 290                 memcpy(skb->nh.raw, tmp_hdr, hdr_len);
 291                 skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 292                 ip6_find_1stfragopt(skb, &prevhdr);
 293                 ret = *prevhdr = nexthdr[1];
 294         }
 295
 296 out:
 297         kfree(tmp_hdr);
 298 out_nofree:
 299         return ret;
 300 }
 301
 302 static u32 esp6_get_max_size(struct xfrm_state *x, int mtu)
 303 {
 304         struct esp_data *esp = x->data;
 305         u32 blksize = crypto_tfm_alg_blocksize(esp->conf.tfm);
 306
 307         if (x->props.mode) {
 308                 mtu = (mtu + 2 + blksize-1)&~(blksize-1);
 309         } else {
 310                 /* The worst case. */
 311                 mtu += 2 + blksize;
 312         }
 313         if (esp->conf.padlen)
 314                 mtu = (mtu + esp->conf.padlen-1)&~(esp->conf.padlen-1);
 315
 316         return mtu + x->props.header_len + esp->auth.icv_full_len;
 317 }
 318
 319 void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 320                 int type, int code, int offset, __u32 info)
 321 {
 322         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 323         struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset);
 324         struct xfrm_state *x;
 325
 326         if (type != ICMPV6_DEST_UNREACH &&
 327             type != ICMPV6_PKT_TOOBIG)
 328                 return;
 329
 330         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6);
 331         if (!x)
 332                 return;
 333         printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/"
 334                         "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
 335                         ntohl(esph->spi), NIP6(iph->daddr));
 336         xfrm_state_put(x);
 337 }
 338
 339 void esp6_destroy(struct xfrm_state *x)
 340 {
 341         struct esp_data *esp = x->data;
 342
 343         if (!esp)
 344                 return;
 345
 346         if (esp->conf.tfm) {
 347                 crypto_free_tfm(esp->conf.tfm);
 348                 esp->conf.tfm = NULL;
 349         }
 350         if (esp->conf.ivec) {
 351                 kfree(esp->conf.ivec);
 352                 esp->conf.ivec = NULL;
 353         }
 354         if (esp->auth.tfm) {
 355                 crypto_free_tfm(esp->auth.tfm);
 356                 esp->auth.tfm = NULL;
 357         }
 358         if (esp->auth.work_icv) {
 359                 kfree(esp->auth.work_icv);
 360                 esp->auth.work_icv = NULL;
 361         }
 362         kfree(esp);
 363 }
 364
 365 int esp6_init_state(struct xfrm_state *x, void *args)
 366 {
 367         struct esp_data *esp = NULL;
 368
 369         if (x->aalg) {
 370                 if (x->aalg->alg_key_len == 0 || x->aalg->alg_key_len > 512)
 371                         goto error;
 372         }
 373         if (x->ealg == NULL)
 374                 goto error;
 375
 376         esp = kmalloc(sizeof(*esp), GFP_KERNEL);
 377         if (esp == NULL)
 378                 return -ENOMEM;
 379
 380         memset(esp, 0, sizeof(*esp));
 381
 382         if (x->aalg) {
 383                 struct xfrm_algo_desc *aalg_desc;
 384
 385                 esp->auth.key = x->aalg->alg_key;
 386                 esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
 387                 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
 388                 if (esp->auth.tfm == NULL)
 389                         goto error;
 390                 esp->auth.icv = esp_hmac_digest;
 391
 392                 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name);
 393                 BUG_ON(!aalg_desc);
 394
 395                 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
 396                         crypto_tfm_alg_digestsize(esp->auth.tfm)) {
 397                                 printk(KERN_INFO "ESP: %s digestsize %u != %hu\n",
 398                                         x->aalg->alg_name,
 399                                         crypto_tfm_alg_digestsize(esp->auth.tfm),
 400                                         aalg_desc->uinfo.auth.icv_fullbits/8);
 401                                 goto error;
 402                 }
 403
 404                 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
 405                 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
 406
 407                 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
 408                 if (!esp->auth.work_icv)
 409                         goto error;
 410         }
 411         esp->conf.key = x->ealg->alg_key;
 412         esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
 413         if (x->props.ealgo == SADB_EALG_NULL)
 414                 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB);
 415         else
 416                 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC);
 417         if (esp->conf.tfm == NULL)
 418                 goto error;
 419         esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm);
 420         esp->conf.padlen = 0;
 421         if (esp->conf.ivlen) {
 422                 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
 423                 if (unlikely(esp->conf.ivec == NULL))
 424                         goto error;
 425                 get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
 426         }
 427         crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len);
 428         x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen;
 429         if (x->props.mode)
 430                 x->props.header_len += sizeof(struct ipv6hdr);
 431         x->data = esp;
 432         return 0;
 433
 434 error:
 435         if (esp) {
 436                 if (esp->auth.tfm)
 437                         crypto_free_tfm(esp->auth.tfm);
 438                 if (esp->auth.work_icv)
 439                         kfree(esp->auth.work_icv);
 440                 if (esp->conf.tfm)
 441                         crypto_free_tfm(esp->conf.tfm);
 442                 kfree(esp);
 443         }
 444         return -EINVAL;
 445 }
 446
 447 static struct xfrm_type esp6_type =
 448 {
 449         .description    = "ESP6",
 450         .owner          = THIS_MODULE,
 451         .proto          = IPPROTO_ESP,
 452         .init_state     = esp6_init_state,
 453         .destructor     = esp6_destroy,
 454         .get_max_size   = esp6_get_max_size,
 455         .input          = esp6_input,
 456         .output         = esp6_output
 457 };
 458
 459 static struct inet6_protocol esp6_protocol = {
 460         .handler        =       xfrm6_rcv,
 461         .err_handler    =       esp6_err,
 462         .flags          =       INET6_PROTO_NOPOLICY,
 463 };
 464
 465 int __init esp6_init(void)
 466 {
 467         if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
 468                 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n");
 469                 return -EAGAIN;
 470         }
 471         if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
 472                 printk(KERN_INFO "ipv6 esp init: can't add protocol\n");
 473                 xfrm_unregister_type(&esp6_type, AF_INET6);
 474                 return -EAGAIN;
 475         }
 476
 477         return 0;
 478 }
 479
 480 static void __exit esp6_fini(void)
 481 {
 482         if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
 483                 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n");
 484         if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
 485                 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n");
 486 }
 487
 488 module_init(esp6_init);
 489 module_exit(esp6_fini);
 490
 491 MODULE_LICENSE("GPL");