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