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/err.h>
  28 #include <linux/module.h>
  29 #include <net/ip.h>
  30 #include <net/xfrm.h>
  31 #include <net/esp.h>
  32 #include <asm/scatterlist.h>
  33 #include <linux/crypto.h>
  34 #include <linux/kernel.h>
  35 #include <linux/pfkeyv2.h>
  36 #include <linux/random.h>
  37 #include <linux/spinlock.h>
  38 #include <net/icmp.h>
  39 #include <net/ipv6.h>
  40 #include <net/protocol.h>
  41 #include <linux/icmpv6.h>
  42
  43 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
  44 {
  45         int err;
  46         struct ip_esp_hdr *esph;
  47         struct crypto_blkcipher *tfm;
  48         struct blkcipher_desc desc;
  49         struct sk_buff *trailer;
  50         int blksize;
  51         int clen;
  52         int alen;
  53         int nfrags;
  54         u8 *tail;
  55         struct esp_data *esp = x->data;
  56
  57         /* skb is pure payload to encrypt */
  58         err = -ENOMEM;
  59
  60         /* Round to block size */
  61         clen = skb->len;
  62
  63         alen = esp->auth.icv_trunc_len;
  64         tfm = esp->conf.tfm;
  65         desc.tfm = tfm;
  66         desc.flags = 0;
  67         blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
  68         clen = ALIGN(clen + 2, blksize);
  69         if (esp->conf.padlen)
  70                 clen = ALIGN(clen, esp->conf.padlen);
  71
  72         if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) {
  73                 goto error;
  74         }
  75
  76         /* Fill padding... */
  77         tail = skb_tail_pointer(trailer);
  78         do {
  79                 int i;
  80                 for (i=0; i<clen-skb->len - 2; i++)
  81                         tail[i] = i + 1;
  82         } while (0);
  83         tail[clen-skb->len - 2] = (clen - skb->len) - 2;
  84         pskb_put(skb, trailer, clen - skb->len);
  85
  86         skb_push(skb, -skb_network_offset(skb));
  87         esph = ip_esp_hdr(skb);
  88         *(skb_tail_pointer(trailer) - 1) = *skb_mac_header(skb);
  89         *skb_mac_header(skb) = IPPROTO_ESP;
  90
  91         esph->spi = x->id.spi;
  92         esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq);
  93
  94         spin_lock_bh(&x->lock);
  95
  96         if (esp->conf.ivlen) {
  97                 if (unlikely(!esp->conf.ivinitted)) {
  98                         get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
  99                         esp->conf.ivinitted = 1;
 100                 }
 101                 crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
 102         }
 103
 104         do {
 105                 struct scatterlist *sg = &esp->sgbuf[0];
 106
 107                 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
 108                         sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
 109                         if (!sg)
 110                                 goto unlock;
 111                 }
 112                 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
 113                 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
 114                 if (unlikely(sg != &esp->sgbuf[0]))
 115                         kfree(sg);
 116         } while (0);
 117
 118         if (unlikely(err))
 119                 goto unlock;
 120
 121         if (esp->conf.ivlen) {
 122                 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
 123                 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
 124         }
 125
 126         if (esp->auth.icv_full_len) {
 127                 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
 128                                      sizeof(*esph) + esp->conf.ivlen + clen);
 129                 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
 130         }
 131
 132 unlock:
 133         spin_unlock_bh(&x->lock);
 134
 135 error:
 136         return err;
 137 }
 138
 139 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
 140 {
 141         struct ipv6hdr *iph;
 142         struct ip_esp_hdr *esph;
 143         struct esp_data *esp = x->data;
 144         struct crypto_blkcipher *tfm = esp->conf.tfm;
 145         struct blkcipher_desc desc = { .tfm = tfm };
 146         struct sk_buff *trailer;
 147         int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
 148         int alen = esp->auth.icv_trunc_len;
 149         int elen = skb->len - sizeof(*esph) - esp->conf.ivlen - alen;
 150         int hdr_len = skb_network_header_len(skb);
 151         int nfrags;
 152         int ret = 0;
 153
 154         if (!pskb_may_pull(skb, sizeof(*esph))) {
 155                 ret = -EINVAL;
 156                 goto out;
 157         }
 158
 159         if (elen <= 0 || (elen & (blksize-1))) {
 160                 ret = -EINVAL;
 161                 goto out;
 162         }
 163
 164         /* If integrity check is required, do this. */
 165         if (esp->auth.icv_full_len) {
 166                 u8 sum[alen];
 167
 168                 ret = esp_mac_digest(esp, skb, 0, skb->len - alen);
 169                 if (ret)
 170                         goto out;
 171
 172                 if (skb_copy_bits(skb, skb->len - alen, sum, alen))
 173                         BUG();
 174
 175                 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
 176                         x->stats.integrity_failed++;
 177                         ret = -EINVAL;
 178                         goto out;
 179                 }
 180         }
 181
 182         if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
 183                 ret = -EINVAL;
 184                 goto out;
 185         }
 186
 187         skb->ip_summed = CHECKSUM_NONE;
 188
 189         esph = (struct ip_esp_hdr *)skb->data;
 190         iph = ipv6_hdr(skb);
 191
 192         /* Get ivec. This can be wrong, check against another impls. */
 193         if (esp->conf.ivlen)
 194                 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
 195
 196         {
 197                 u8 nexthdr[2];
 198                 struct scatterlist *sg = &esp->sgbuf[0];
 199                 u8 padlen;
 200
 201                 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
 202                         sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
 203                         if (!sg) {
 204                                 ret = -ENOMEM;
 205                                 goto out;
 206                         }
 207                 }
 208                 skb_to_sgvec(skb, sg, sizeof(*esph) + esp->conf.ivlen, elen);
 209                 ret = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
 210                 if (unlikely(sg != &esp->sgbuf[0]))
 211                         kfree(sg);
 212                 if (unlikely(ret))
 213                         goto out;
 214
 215                 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
 216                         BUG();
 217
 218                 padlen = nexthdr[0];
 219                 if (padlen+2 >= elen) {
 220                         LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen);
 221                         ret = -EINVAL;
 222                         goto out;
 223                 }
 224                 /* ... check padding bits here. Silly. :-) */
 225
 226                 pskb_trim(skb, skb->len - alen - padlen - 2);
 227                 ret = nexthdr[1];
 228         }
 229
 230         __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen);
 231         skb_set_transport_header(skb, -hdr_len);
 232 out:
 233         return ret;
 234 }
 235
 236 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu)
 237 {
 238         struct esp_data *esp = x->data;
 239         u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
 240         u32 align = max_t(u32, blksize, esp->conf.padlen);
 241         u32 rem;
 242
 243         mtu -= x->props.header_len + esp->auth.icv_trunc_len;
 244         rem = mtu & (align - 1);
 245         mtu &= ~(align - 1);
 246
 247         if (x->props.mode != XFRM_MODE_TUNNEL) {
 248                 u32 padsize = ((blksize - 1) & 7) + 1;
 249                 mtu -= blksize - padsize;
 250                 mtu += min_t(u32, blksize - padsize, rem);
 251         }
 252
 253         return mtu - 2;
 254 }
 255
 256 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 257                      int type, int code, int offset, __be32 info)
 258 {
 259         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 260         struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset);
 261         struct xfrm_state *x;
 262
 263         if (type != ICMPV6_DEST_UNREACH &&
 264             type != ICMPV6_PKT_TOOBIG)
 265                 return;
 266
 267         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6);
 268         if (!x)
 269                 return;
 270         printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n",
 271                         ntohl(esph->spi), NIP6(iph->daddr));
 272         xfrm_state_put(x);
 273 }
 274
 275 static void esp6_destroy(struct xfrm_state *x)
 276 {
 277         struct esp_data *esp = x->data;
 278
 279         if (!esp)
 280                 return;
 281
 282         crypto_free_blkcipher(esp->conf.tfm);
 283         esp->conf.tfm = NULL;
 284         kfree(esp->conf.ivec);
 285         esp->conf.ivec = NULL;
 286         crypto_free_hash(esp->auth.tfm);
 287         esp->auth.tfm = NULL;
 288         kfree(esp->auth.work_icv);
 289         esp->auth.work_icv = NULL;
 290         kfree(esp);
 291 }
 292
 293 static int esp6_init_state(struct xfrm_state *x)
 294 {
 295         struct esp_data *esp = NULL;
 296         struct crypto_blkcipher *tfm;
 297
 298         if (x->ealg == NULL)
 299                 goto error;
 300
 301         if (x->encap)
 302                 goto error;
 303
 304         esp = kzalloc(sizeof(*esp), GFP_KERNEL);
 305         if (esp == NULL)
 306                 return -ENOMEM;
 307
 308         if (x->aalg) {
 309                 struct xfrm_algo_desc *aalg_desc;
 310                 struct crypto_hash *hash;
 311
 312                 hash = crypto_alloc_hash(x->aalg->alg_name, 0,
 313                                          CRYPTO_ALG_ASYNC);
 314                 if (IS_ERR(hash))
 315                         goto error;
 316
 317                 esp->auth.tfm = hash;
 318                 if (crypto_hash_setkey(hash, x->aalg->alg_key,
 319                                        (x->aalg->alg_key_len + 7) / 8))
 320                         goto error;
 321
 322                 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
 323                 BUG_ON(!aalg_desc);
 324
 325                 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
 326                     crypto_hash_digestsize(hash)) {
 327                         NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
 328                                  x->aalg->alg_name,
 329                                  crypto_hash_digestsize(hash),
 330                                  aalg_desc->uinfo.auth.icv_fullbits/8);
 331                         goto error;
 332                 }
 333
 334                 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
 335                 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
 336
 337                 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
 338                 if (!esp->auth.work_icv)
 339                         goto error;
 340         }
 341         tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
 342         if (IS_ERR(tfm))
 343                 goto error;
 344         esp->conf.tfm = tfm;
 345         esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
 346         esp->conf.padlen = 0;
 347         if (esp->conf.ivlen) {
 348                 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
 349                 if (unlikely(esp->conf.ivec == NULL))
 350                         goto error;
 351                 esp->conf.ivinitted = 0;
 352         }
 353         if (crypto_blkcipher_setkey(tfm, x->ealg->alg_key,
 354                                     (x->ealg->alg_key_len + 7) / 8))
 355                 goto error;
 356         x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
 357         if (x->props.mode == XFRM_MODE_TUNNEL)
 358                 x->props.header_len += sizeof(struct ipv6hdr);
 359         x->data = esp;
 360         return 0;
 361
 362 error:
 363         x->data = esp;
 364         esp6_destroy(x);
 365         x->data = NULL;
 366         return -EINVAL;
 367 }
 368
 369 static struct xfrm_type esp6_type =
 370 {
 371         .description    = "ESP6",
 372         .owner          = THIS_MODULE,
 373         .proto          = IPPROTO_ESP,
 374         .flags          = XFRM_TYPE_REPLAY_PROT,
 375         .init_state     = esp6_init_state,
 376         .destructor     = esp6_destroy,
 377         .get_mtu        = esp6_get_mtu,
 378         .input          = esp6_input,
 379         .output         = esp6_output,
 380         .hdr_offset     = xfrm6_find_1stfragopt,
 381 };
 382
 383 static struct inet6_protocol esp6_protocol = {
 384         .handler        =       xfrm6_rcv,
 385         .err_handler    =       esp6_err,
 386         .flags          =       INET6_PROTO_NOPOLICY,
 387 };
 388
 389 static int __init esp6_init(void)
 390 {
 391         if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
 392                 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n");
 393                 return -EAGAIN;
 394         }
 395         if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
 396                 printk(KERN_INFO "ipv6 esp init: can't add protocol\n");
 397                 xfrm_unregister_type(&esp6_type, AF_INET6);
 398                 return -EAGAIN;
 399         }
 400
 401         return 0;
 402 }
 403
 404 static void __exit esp6_fini(void)
 405 {
 406         if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
 407                 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n");
 408         if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
 409                 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n");
 410 }
 411
 412 module_init(esp6_init);
 413 module_exit(esp6_fini);
 414
 415 MODULE_LICENSE("GPL");
 416 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP);