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 <net/icmp.h>
  38 #include <net/ipv6.h>
  39 #include <net/protocol.h>
  40 #include <linux/icmpv6.h>
  41
  42 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
  43 {
  44         int err;
  45         struct ipv6hdr *top_iph;
  46         struct ipv6_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         int hdr_len = (skb_transport_offset(skb) +
  57                        sizeof(*esph) + esp->conf.ivlen);
  58
  59         /* Strip IP+ESP header. */
  60         __skb_pull(skb, hdr_len);
  61
  62         /* Now skb is pure payload to encrypt */
  63         err = -ENOMEM;
  64
  65         /* Round to block size */
  66         clen = skb->len;
  67
  68         alen = esp->auth.icv_trunc_len;
  69         tfm = esp->conf.tfm;
  70         desc.tfm = tfm;
  71         desc.flags = 0;
  72         blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
  73         clen = ALIGN(clen + 2, blksize);
  74         if (esp->conf.padlen)
  75                 clen = ALIGN(clen, esp->conf.padlen);
  76
  77         if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) {
  78                 goto error;
  79         }
  80
  81         /* Fill padding... */
  82         tail = skb_tail_pointer(trailer);
  83         do {
  84                 int i;
  85                 for (i=0; i<clen-skb->len - 2; i++)
  86                         tail[i] = i + 1;
  87         } while (0);
  88         tail[clen-skb->len - 2] = (clen - skb->len) - 2;
  89         pskb_put(skb, trailer, clen - skb->len);
  90
  91         top_iph = (struct ipv6hdr *)__skb_push(skb, hdr_len);
  92         esph = (struct ipv6_esp_hdr *)skb_transport_header(skb);
  93         top_iph->payload_len = htons(skb->len + alen - sizeof(*top_iph));
  94         *(skb_tail_pointer(trailer) - 1) = *skb_network_header(skb);
  95         *skb_network_header(skb) = IPPROTO_ESP;
  96
  97         esph->spi = x->id.spi;
  98         esph->seq_no = htonl(++x->replay.oseq);
  99         xfrm_aevent_doreplay(x);
 100
 101         if (esp->conf.ivlen) {
 102                 if (unlikely(!esp->conf.ivinitted)) {
 103                         get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
 104                         esp->conf.ivinitted = 1;
 105                 }
 106                 crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
 107         }
 108
 109         do {
 110                 struct scatterlist *sg = &esp->sgbuf[0];
 111
 112                 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
 113                         sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
 114                         if (!sg)
 115                                 goto error;
 116                 }
 117                 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
 118                 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
 119                 if (unlikely(sg != &esp->sgbuf[0]))
 120                         kfree(sg);
 121         } while (0);
 122
 123         if (unlikely(err))
 124                 goto error;
 125
 126         if (esp->conf.ivlen) {
 127                 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
 128                 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
 129         }
 130
 131         if (esp->auth.icv_full_len) {
 132                 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
 133                                      sizeof(*esph) + esp->conf.ivlen + clen);
 134                 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
 135         }
 136
 137 error:
 138         return err;
 139 }
 140
 141 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
 142 {
 143         struct ipv6hdr *iph;
 144         struct ipv6_esp_hdr *esph;
 145         struct esp_data *esp = x->data;
 146         struct crypto_blkcipher *tfm = esp->conf.tfm;
 147         struct blkcipher_desc desc = { .tfm = tfm };
 148         struct sk_buff *trailer;
 149         int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
 150         int alen = esp->auth.icv_trunc_len;
 151         int elen = skb->len - sizeof(struct ipv6_esp_hdr) - esp->conf.ivlen - alen;
 152         int hdr_len = skb_network_header_len(skb);
 153         int nfrags;
 154         int ret = 0;
 155
 156         if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) {
 157                 ret = -EINVAL;
 158                 goto out;
 159         }
 160
 161         if (elen <= 0 || (elen & (blksize-1))) {
 162                 ret = -EINVAL;
 163                 goto out;
 164         }
 165
 166         /* If integrity check is required, do this. */
 167         if (esp->auth.icv_full_len) {
 168                 u8 sum[alen];
 169
 170                 ret = esp_mac_digest(esp, skb, 0, skb->len - alen);
 171                 if (ret)
 172                         goto out;
 173
 174                 if (skb_copy_bits(skb, skb->len - alen, sum, alen))
 175                         BUG();
 176
 177                 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
 178                         x->stats.integrity_failed++;
 179                         ret = -EINVAL;
 180                         goto out;
 181                 }
 182         }
 183
 184         if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
 185                 ret = -EINVAL;
 186                 goto out;
 187         }
 188
 189         skb->ip_summed = CHECKSUM_NONE;
 190
 191         esph = (struct ipv6_esp_hdr*)skb->data;
 192         iph = ipv6_hdr(skb);
 193
 194         /* Get ivec. This can be wrong, check against another impls. */
 195         if (esp->conf.ivlen)
 196                 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
 197
 198         {
 199                 u8 nexthdr[2];
 200                 struct scatterlist *sg = &esp->sgbuf[0];
 201                 u8 padlen;
 202
 203                 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
 204                         sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
 205                         if (!sg) {
 206                                 ret = -ENOMEM;
 207                                 goto out;
 208                         }
 209                 }
 210                 skb_to_sgvec(skb, sg, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen, elen);
 211                 ret = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
 212                 if (unlikely(sg != &esp->sgbuf[0]))
 213                         kfree(sg);
 214                 if (unlikely(ret))
 215                         goto out;
 216
 217                 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
 218                         BUG();
 219
 220                 padlen = nexthdr[0];
 221                 if (padlen+2 >= elen) {
 222                         LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen);
 223                         ret = -EINVAL;
 224                         goto out;
 225                 }
 226                 /* ... check padding bits here. Silly. :-) */
 227
 228                 pskb_trim(skb, skb->len - alen - padlen - 2);
 229                 ret = nexthdr[1];
 230         }
 231
 232         __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen);
 233         skb_set_transport_header(skb, -hdr_len);
 234 out:
 235         return ret;
 236 }
 237
 238 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu)
 239 {
 240         struct esp_data *esp = x->data;
 241         u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
 242         u32 align = max_t(u32, blksize, esp->conf.padlen);
 243         u32 rem;
 244
 245         mtu -= x->props.header_len + esp->auth.icv_trunc_len;
 246         rem = mtu & (align - 1);
 247         mtu &= ~(align - 1);
 248
 249         if (x->props.mode != XFRM_MODE_TUNNEL) {
 250                 u32 padsize = ((blksize - 1) & 7) + 1;
 251                 mtu -= blksize - padsize;
 252                 mtu += min_t(u32, blksize - padsize, rem);
 253         }
 254
 255         return mtu - 2;
 256 }
 257
 258 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 259                      int type, int code, int offset, __be32 info)
 260 {
 261         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 262         struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset);
 263         struct xfrm_state *x;
 264
 265         if (type != ICMPV6_DEST_UNREACH &&
 266             type != ICMPV6_PKT_TOOBIG)
 267                 return;
 268
 269         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6);
 270         if (!x)
 271                 return;
 272         printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n",
 273                         ntohl(esph->spi), NIP6(iph->daddr));
 274         xfrm_state_put(x);
 275 }
 276
 277 static void esp6_destroy(struct xfrm_state *x)
 278 {
 279         struct esp_data *esp = x->data;
 280
 281         if (!esp)
 282                 return;
 283
 284         crypto_free_blkcipher(esp->conf.tfm);
 285         esp->conf.tfm = NULL;
 286         kfree(esp->conf.ivec);
 287         esp->conf.ivec = NULL;
 288         crypto_free_hash(esp->auth.tfm);
 289         esp->auth.tfm = NULL;
 290         kfree(esp->auth.work_icv);
 291         esp->auth.work_icv = NULL;
 292         kfree(esp);
 293 }
 294
 295 static int esp6_init_state(struct xfrm_state *x)
 296 {
 297         struct esp_data *esp = NULL;
 298         struct crypto_blkcipher *tfm;
 299
 300         /* null auth and encryption can have zero length keys */
 301         if (x->aalg) {
 302                 if (x->aalg->alg_key_len > 512)
 303                         goto error;
 304         }
 305         if (x->ealg == NULL)
 306                 goto error;
 307
 308         if (x->encap)
 309                 goto error;
 310
 311         esp = kzalloc(sizeof(*esp), GFP_KERNEL);
 312         if (esp == NULL)
 313                 return -ENOMEM;
 314
 315         if (x->aalg) {
 316                 struct xfrm_algo_desc *aalg_desc;
 317                 struct crypto_hash *hash;
 318
 319                 esp->auth.key = x->aalg->alg_key;
 320                 esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
 321                 hash = crypto_alloc_hash(x->aalg->alg_name, 0,
 322                                          CRYPTO_ALG_ASYNC);
 323                 if (IS_ERR(hash))
 324                         goto error;
 325
 326                 esp->auth.tfm = hash;
 327                 if (crypto_hash_setkey(hash, esp->auth.key, esp->auth.key_len))
 328                         goto error;
 329
 330                 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
 331                 BUG_ON(!aalg_desc);
 332
 333                 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
 334                     crypto_hash_digestsize(hash)) {
 335                         NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
 336                                  x->aalg->alg_name,
 337                                  crypto_hash_digestsize(hash),
 338                                  aalg_desc->uinfo.auth.icv_fullbits/8);
 339                         goto error;
 340                 }
 341
 342                 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
 343                 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
 344
 345                 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
 346                 if (!esp->auth.work_icv)
 347                         goto error;
 348         }
 349         esp->conf.key = x->ealg->alg_key;
 350         esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
 351         tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
 352         if (IS_ERR(tfm))
 353                 goto error;
 354         esp->conf.tfm = tfm;
 355         esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
 356         esp->conf.padlen = 0;
 357         if (esp->conf.ivlen) {
 358                 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
 359                 if (unlikely(esp->conf.ivec == NULL))
 360                         goto error;
 361                 esp->conf.ivinitted = 0;
 362         }
 363         if (crypto_blkcipher_setkey(tfm, esp->conf.key, esp->conf.key_len))
 364                 goto error;
 365         x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen;
 366         if (x->props.mode == XFRM_MODE_TUNNEL)
 367                 x->props.header_len += sizeof(struct ipv6hdr);
 368         x->data = esp;
 369         return 0;
 370
 371 error:
 372         x->data = esp;
 373         esp6_destroy(x);
 374         x->data = NULL;
 375         return -EINVAL;
 376 }
 377
 378 static struct xfrm_type esp6_type =
 379 {
 380         .description    = "ESP6",
 381         .owner          = THIS_MODULE,
 382         .proto          = IPPROTO_ESP,
 383         .init_state     = esp6_init_state,
 384         .destructor     = esp6_destroy,
 385         .get_mtu        = esp6_get_mtu,
 386         .input          = esp6_input,
 387         .output         = esp6_output,
 388         .hdr_offset     = xfrm6_find_1stfragopt,
 389 };
 390
 391 static struct inet6_protocol esp6_protocol = {
 392         .handler        =       xfrm6_rcv,
 393         .err_handler    =       esp6_err,
 394         .flags          =       INET6_PROTO_NOPOLICY,
 395 };
 396
 397 static int __init esp6_init(void)
 398 {
 399         if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
 400                 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n");
 401                 return -EAGAIN;
 402         }
 403         if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
 404                 printk(KERN_INFO "ipv6 esp init: can't add protocol\n");
 405                 xfrm_unregister_type(&esp6_type, AF_INET6);
 406                 return -EAGAIN;
 407         }
 408
 409         return 0;
 410 }
 411
 412 static void __exit esp6_fini(void)
 413 {
 414         if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
 415                 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n");
 416         if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
 417                 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n");
 418 }
 419
 420 module_init(esp6_init);
 421 module_exit(esp6_fini);
 422
 423 MODULE_LICENSE("GPL");