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 <linux/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                 sg_init_table(sg, nfrags);
 113                 skb_to_sgvec(skb, sg,
 114                              esph->enc_data +
 115                              esp->conf.ivlen -
 116                              skb->data, clen);
 117                 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
 118                 if (unlikely(sg != &esp->sgbuf[0]))
 119                         kfree(sg);
 120         } while (0);
 121
 122         if (unlikely(err))
 123                 goto unlock;
 124
 125         if (esp->conf.ivlen) {
 126                 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
 127                 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
 128         }
 129
 130         if (esp->auth.icv_full_len) {
 131                 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
 132                                      sizeof(*esph) + esp->conf.ivlen + clen);
 133                 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
 134         }
 135
 136 unlock:
 137         spin_unlock_bh(&x->lock);
 138
 139 error:
 140         return err;
 141 }
 142
 143 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
 144 {
 145         struct ipv6hdr *iph;
 146         struct ip_esp_hdr *esph;
 147         struct esp_data *esp = x->data;
 148         struct crypto_blkcipher *tfm = esp->conf.tfm;
 149         struct blkcipher_desc desc = { .tfm = tfm };
 150         struct sk_buff *trailer;
 151         int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
 152         int alen = esp->auth.icv_trunc_len;
 153         int elen = skb->len - sizeof(*esph) - esp->conf.ivlen - alen;
 154         int hdr_len = skb_network_header_len(skb);
 155         int nfrags;
 156         int ret = 0;
 157
 158         if (!pskb_may_pull(skb, sizeof(*esph))) {
 159                 ret = -EINVAL;
 160                 goto out;
 161         }
 162
 163         if (elen <= 0 || (elen & (blksize-1))) {
 164                 ret = -EINVAL;
 165                 goto out;
 166         }
 167
 168         /* If integrity check is required, do this. */
 169         if (esp->auth.icv_full_len) {
 170                 u8 sum[alen];
 171
 172                 ret = esp_mac_digest(esp, skb, 0, skb->len - alen);
 173                 if (ret)
 174                         goto out;
 175
 176                 if (skb_copy_bits(skb, skb->len - alen, sum, alen))
 177                         BUG();
 178
 179                 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
 180                         x->stats.integrity_failed++;
 181                         ret = -EINVAL;
 182                         goto out;
 183                 }
 184         }
 185
 186         if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
 187                 ret = -EINVAL;
 188                 goto out;
 189         }
 190
 191         skb->ip_summed = CHECKSUM_NONE;
 192
 193         esph = (struct ip_esp_hdr *)skb->data;
 194         iph = ipv6_hdr(skb);
 195
 196         /* Get ivec. This can be wrong, check against another impls. */
 197         if (esp->conf.ivlen)
 198                 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
 199
 200         {
 201                 u8 nexthdr[2];
 202                 struct scatterlist *sg = &esp->sgbuf[0];
 203                 u8 padlen;
 204
 205                 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
 206                         sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
 207                         if (!sg) {
 208                                 ret = -ENOMEM;
 209                                 goto out;
 210                         }
 211                 }
 212                 sg_init_table(sg, nfrags);
 213                 skb_to_sgvec(skb, sg,
 214                              sizeof(*esph) + esp->conf.ivlen,
 215                              elen);
 216                 ret = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
 217                 if (unlikely(sg != &esp->sgbuf[0]))
 218                         kfree(sg);
 219                 if (unlikely(ret))
 220                         goto out;
 221
 222                 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
 223                         BUG();
 224
 225                 padlen = nexthdr[0];
 226                 if (padlen+2 >= elen) {
 227                         LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen);
 228                         ret = -EINVAL;
 229                         goto out;
 230                 }
 231                 /* ... check padding bits here. Silly. :-) */
 232
 233                 /* RFC4303: Drop dummy packets without any error */
 234                 if (nexthdr[1] == IPPROTO_NONE) {
 235                         ret = -EINVAL;
 236                         goto out;
 237                 }
 238
 239                 pskb_trim(skb, skb->len - alen - padlen - 2);
 240                 ret = nexthdr[1];
 241         }
 242
 243         __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen);
 244         skb_set_transport_header(skb, -hdr_len);
 245 out:
 246         return ret;
 247 }
 248
 249 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu)
 250 {
 251         struct esp_data *esp = x->data;
 252         u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
 253         u32 align = max_t(u32, blksize, esp->conf.padlen);
 254         u32 rem;
 255
 256         mtu -= x->props.header_len + esp->auth.icv_trunc_len;
 257         rem = mtu & (align - 1);
 258         mtu &= ~(align - 1);
 259
 260         if (x->props.mode != XFRM_MODE_TUNNEL) {
 261                 u32 padsize = ((blksize - 1) & 7) + 1;
 262                 mtu -= blksize - padsize;
 263                 mtu += min_t(u32, blksize - padsize, rem);
 264         }
 265
 266         return mtu - 2;
 267 }
 268
 269 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 270                      int type, int code, int offset, __be32 info)
 271 {
 272         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 273         struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset);
 274         struct xfrm_state *x;
 275
 276         if (type != ICMPV6_DEST_UNREACH &&
 277             type != ICMPV6_PKT_TOOBIG)
 278                 return;
 279
 280         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6);
 281         if (!x)
 282                 return;
 283         printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n",
 284                         ntohl(esph->spi), NIP6(iph->daddr));
 285         xfrm_state_put(x);
 286 }
 287
 288 static void esp6_destroy(struct xfrm_state *x)
 289 {
 290         struct esp_data *esp = x->data;
 291
 292         if (!esp)
 293                 return;
 294
 295         crypto_free_blkcipher(esp->conf.tfm);
 296         esp->conf.tfm = NULL;
 297         kfree(esp->conf.ivec);
 298         esp->conf.ivec = NULL;
 299         crypto_free_hash(esp->auth.tfm);
 300         esp->auth.tfm = NULL;
 301         kfree(esp->auth.work_icv);
 302         esp->auth.work_icv = NULL;
 303         kfree(esp);
 304 }
 305
 306 static int esp6_init_state(struct xfrm_state *x)
 307 {
 308         struct esp_data *esp = NULL;
 309         struct crypto_blkcipher *tfm;
 310
 311         if (x->ealg == NULL)
 312                 goto error;
 313
 314         if (x->encap)
 315                 goto error;
 316
 317         esp = kzalloc(sizeof(*esp), GFP_KERNEL);
 318         if (esp == NULL)
 319                 return -ENOMEM;
 320
 321         if (x->aalg) {
 322                 struct xfrm_algo_desc *aalg_desc;
 323                 struct crypto_hash *hash;
 324
 325                 hash = crypto_alloc_hash(x->aalg->alg_name, 0,
 326                                          CRYPTO_ALG_ASYNC);
 327                 if (IS_ERR(hash))
 328                         goto error;
 329
 330                 esp->auth.tfm = hash;
 331                 if (crypto_hash_setkey(hash, x->aalg->alg_key,
 332                                        (x->aalg->alg_key_len + 7) / 8))
 333                         goto error;
 334
 335                 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
 336                 BUG_ON(!aalg_desc);
 337
 338                 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
 339                     crypto_hash_digestsize(hash)) {
 340                         NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
 341                                  x->aalg->alg_name,
 342                                  crypto_hash_digestsize(hash),
 343                                  aalg_desc->uinfo.auth.icv_fullbits/8);
 344                         goto error;
 345                 }
 346
 347                 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
 348                 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
 349
 350                 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
 351                 if (!esp->auth.work_icv)
 352                         goto error;
 353         }
 354         tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
 355         if (IS_ERR(tfm))
 356                 goto error;
 357         esp->conf.tfm = tfm;
 358         esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
 359         esp->conf.padlen = 0;
 360         if (esp->conf.ivlen) {
 361                 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
 362                 if (unlikely(esp->conf.ivec == NULL))
 363                         goto error;
 364                 esp->conf.ivinitted = 0;
 365         }
 366         if (crypto_blkcipher_setkey(tfm, x->ealg->alg_key,
 367                                     (x->ealg->alg_key_len + 7) / 8))
 368                 goto error;
 369         x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
 370         switch (x->props.mode) {
 371         case XFRM_MODE_BEET:
 372         case XFRM_MODE_TRANSPORT:
 373                 break;
 374         case XFRM_MODE_TUNNEL:
 375                 x->props.header_len += sizeof(struct ipv6hdr);
 376                 break;
 377         default:
 378                 goto error;
 379         }
 380         x->data = esp;
 381         return 0;
 382
 383 error:
 384         x->data = esp;
 385         esp6_destroy(x);
 386         x->data = NULL;
 387         return -EINVAL;
 388 }
 389
 390 static struct xfrm_type esp6_type =
 391 {
 392         .description    = "ESP6",
 393         .owner          = THIS_MODULE,
 394         .proto          = IPPROTO_ESP,
 395         .flags          = XFRM_TYPE_REPLAY_PROT,
 396         .init_state     = esp6_init_state,
 397         .destructor     = esp6_destroy,
 398         .get_mtu        = esp6_get_mtu,
 399         .input          = esp6_input,
 400         .output         = esp6_output,
 401         .hdr_offset     = xfrm6_find_1stfragopt,
 402 };
 403
 404 static struct inet6_protocol esp6_protocol = {
 405         .handler        =       xfrm6_rcv,
 406         .err_handler    =       esp6_err,
 407         .flags          =       INET6_PROTO_NOPOLICY,
 408 };
 409
 410 static int __init esp6_init(void)
 411 {
 412         if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
 413                 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n");
 414                 return -EAGAIN;
 415         }
 416         if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
 417                 printk(KERN_INFO "ipv6 esp init: can't add protocol\n");
 418                 xfrm_unregister_type(&esp6_type, AF_INET6);
 419                 return -EAGAIN;
 420         }
 421
 422         return 0;
 423 }
 424
 425 static void __exit esp6_fini(void)
 426 {
 427         if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
 428                 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n");
 429         if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
 430                 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n");
 431 }
 432
 433 module_init(esp6_init);
 434 module_exit(esp6_fini);
 435
 436 MODULE_LICENSE("GPL");
 437 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP);