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