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/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         int hdr_len;
  46         struct ipv6hdr *top_iph;
  47         struct ipv6_esp_hdr *esph;
  48         struct crypto_tfm *tfm;
  49         struct esp_data *esp;
  50         struct sk_buff *trailer;
  51         int blksize;
  52         int clen;
  53         int alen;
  54         int nfrags;
  55
  56         esp = x->data;
  57         hdr_len = skb->h.raw - skb->data +
  58                   sizeof(*esph) + esp->conf.ivlen;
  59
  60         /* Strip IP+ESP header. */
  61         __skb_pull(skb, hdr_len);
  62
  63         /* Now skb is pure payload to encrypt */
  64         err = -ENOMEM;
  65
  66         /* Round to block size */
  67         clen = skb->len;
  68
  69         alen = esp->auth.icv_trunc_len;
  70         tfm = esp->conf.tfm;
  71         blksize = ALIGN(crypto_tfm_alg_blocksize(tfm), 4);
  72         clen = ALIGN(clen + 2, blksize);
  73         if (esp->conf.padlen)
  74                 clen = ALIGN(clen, esp->conf.padlen);
  75
  76         if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) {
  77                 goto error;
  78         }
  79
  80         /* Fill padding... */
  81         do {
  82                 int i;
  83                 for (i=0; i<clen-skb->len - 2; i++)
  84                         *(u8*)(trailer->tail + i) = i+1;
  85         } while (0);
  86         *(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2;
  87         pskb_put(skb, trailer, clen - skb->len);
  88
  89         top_iph = (struct ipv6hdr *)__skb_push(skb, hdr_len);
  90         esph = (struct ipv6_esp_hdr *)skb->h.raw;
  91         top_iph->payload_len = htons(skb->len + alen - sizeof(*top_iph));
  92         *(u8*)(trailer->tail - 1) = *skb->nh.raw;
  93         *skb->nh.raw = IPPROTO_ESP;
  94
  95         esph->spi = x->id.spi;
  96         esph->seq_no = htonl(++x->replay.oseq);
  97
  98         if (esp->conf.ivlen)
  99                 crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
 100
 101         do {
 102                 struct scatterlist *sg = &esp->sgbuf[0];
 103
 104                 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
 105                         sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
 106                         if (!sg)
 107                                 goto error;
 108                 }
 109                 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
 110                 crypto_cipher_encrypt(tfm, sg, sg, clen);
 111                 if (unlikely(sg != &esp->sgbuf[0]))
 112                         kfree(sg);
 113         } while (0);
 114
 115         if (esp->conf.ivlen) {
 116                 memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
 117                 crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
 118         }
 119
 120         if (esp->auth.icv_full_len) {
 121                 esp->auth.icv(esp, skb, (u8*)esph-skb->data,
 122                         sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen+clen, trailer->tail);
 123                 pskb_put(skb, trailer, alen);
 124         }
 125
 126         err = 0;
 127
 128 error:
 129         return err;
 130 }
 131
 132 static int esp6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
 133 {
 134         struct ipv6hdr *iph;
 135         struct ipv6_esp_hdr *esph;
 136         struct esp_data *esp = x->data;
 137         struct sk_buff *trailer;
 138         int blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4);
 139         int alen = esp->auth.icv_trunc_len;
 140         int elen = skb->len - sizeof(struct ipv6_esp_hdr) - esp->conf.ivlen - alen;
 141
 142         int hdr_len = skb->h.raw - skb->nh.raw;
 143         int nfrags;
 144         unsigned char *tmp_hdr = NULL;
 145         int ret = 0;
 146
 147         if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) {
 148                 ret = -EINVAL;
 149                 goto out_nofree;
 150         }
 151
 152         if (elen <= 0 || (elen & (blksize-1))) {
 153                 ret = -EINVAL;
 154                 goto out_nofree;
 155         }
 156
 157         tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
 158         if (!tmp_hdr) {
 159                 ret = -ENOMEM;
 160                 goto out_nofree;
 161         }
 162         memcpy(tmp_hdr, skb->nh.raw, hdr_len);
 163
 164         /* If integrity check is required, do this. */
 165         if (esp->auth.icv_full_len) {
 166                 u8 sum[esp->auth.icv_full_len];
 167                 u8 sum1[alen];
 168
 169                 esp->auth.icv(esp, skb, 0, skb->len-alen, sum);
 170
 171                 if (skb_copy_bits(skb, skb->len-alen, sum1, alen))
 172                         BUG();
 173
 174                 if (unlikely(memcmp(sum, sum1, alen))) {
 175                         x->stats.integrity_failed++;
 176                         ret = -EINVAL;
 177                         goto out;
 178                 }
 179         }
 180
 181         if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
 182                 ret = -EINVAL;
 183                 goto out;
 184         }
 185
 186         skb->ip_summed = CHECKSUM_NONE;
 187
 188         esph = (struct ipv6_esp_hdr*)skb->data;
 189         iph = skb->nh.ipv6h;
 190
 191         /* Get ivec. This can be wrong, check against another impls. */
 192         if (esp->conf.ivlen)
 193                 crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm));
 194
 195         {
 196                 u8 nexthdr[2];
 197                 struct scatterlist *sg = &esp->sgbuf[0];
 198                 u8 padlen;
 199
 200                 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
 201                         sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
 202                         if (!sg) {
 203                                 ret = -ENOMEM;
 204                                 goto out;
 205                         }
 206                 }
 207                 skb_to_sgvec(skb, sg, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen, elen);
 208                 crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen);
 209                 if (unlikely(sg != &esp->sgbuf[0]))
 210                         kfree(sg);
 211
 212                 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
 213                         BUG();
 214
 215                 padlen = nexthdr[0];
 216                 if (padlen+2 >= elen) {
 217                         LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen);
 218                         ret = -EINVAL;
 219                         goto out;
 220                 }
 221                 /* ... check padding bits here. Silly. :-) */
 222
 223                 pskb_trim(skb, skb->len - alen - padlen - 2);
 224                 skb->h.raw = skb_pull(skb, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen);
 225                 skb->nh.raw += sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen;
 226                 memcpy(skb->nh.raw, tmp_hdr, hdr_len);
 227                 skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 228                 ret = nexthdr[1];
 229         }
 230
 231 out:
 232         kfree(tmp_hdr);
 233 out_nofree:
 234         return ret;
 235 }
 236
 237 static u32 esp6_get_max_size(struct xfrm_state *x, int mtu)
 238 {
 239         struct esp_data *esp = x->data;
 240         u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4);
 241
 242         if (x->props.mode) {
 243                 mtu = ALIGN(mtu + 2, blksize);
 244         } else {
 245                 /* The worst case. */
 246                 u32 padsize = ((blksize - 1) & 7) + 1;
 247                 mtu = ALIGN(mtu + 2, padsize) + blksize - padsize;
 248         }
 249         if (esp->conf.padlen)
 250                 mtu = ALIGN(mtu, esp->conf.padlen);
 251
 252         return mtu + x->props.header_len + esp->auth.icv_trunc_len;
 253 }
 254
 255 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 256                      int type, int code, int offset, __u32 info)
 257 {
 258         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 259         struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset);
 260         struct xfrm_state *x;
 261
 262         if (type != ICMPV6_DEST_UNREACH &&
 263             type != ICMPV6_PKT_TOOBIG)
 264                 return;
 265
 266         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6);
 267         if (!x)
 268                 return;
 269         printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n",
 270                         ntohl(esph->spi), NIP6(iph->daddr));
 271         xfrm_state_put(x);
 272 }
 273
 274 static void esp6_destroy(struct xfrm_state *x)
 275 {
 276         struct esp_data *esp = x->data;
 277
 278         if (!esp)
 279                 return;
 280
 281         crypto_free_tfm(esp->conf.tfm);
 282         esp->conf.tfm = NULL;
 283         kfree(esp->conf.ivec);
 284         esp->conf.ivec = NULL;
 285         crypto_free_tfm(esp->auth.tfm);
 286         esp->auth.tfm = NULL;
 287         kfree(esp->auth.work_icv);
 288         esp->auth.work_icv = NULL;
 289         kfree(esp);
 290 }
 291
 292 static int esp6_init_state(struct xfrm_state *x)
 293 {
 294         struct esp_data *esp = NULL;
 295
 296         /* null auth and encryption can have zero length keys */
 297         if (x->aalg) {
 298                 if (x->aalg->alg_key_len > 512)
 299                         goto error;
 300         }
 301         if (x->ealg == NULL)
 302                 goto error;
 303
 304         if (x->encap)
 305                 goto error;
 306
 307         esp = kmalloc(sizeof(*esp), GFP_KERNEL);
 308         if (esp == NULL)
 309                 return -ENOMEM;
 310
 311         memset(esp, 0, sizeof(*esp));
 312
 313         if (x->aalg) {
 314                 struct xfrm_algo_desc *aalg_desc;
 315
 316                 esp->auth.key = x->aalg->alg_key;
 317                 esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
 318                 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
 319                 if (esp->auth.tfm == NULL)
 320                         goto error;
 321                 esp->auth.icv = esp_hmac_digest;
 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_tfm_alg_digestsize(esp->auth.tfm)) {
 328                                 printk(KERN_INFO "ESP: %s digestsize %u != %hu\n",
 329                                         x->aalg->alg_name,
 330                                         crypto_tfm_alg_digestsize(esp->auth.tfm),
 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         esp->conf.key = x->ealg->alg_key;
 343         esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
 344         if (x->props.ealgo == SADB_EALG_NULL)
 345                 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB);
 346         else
 347                 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC);
 348         if (esp->conf.tfm == NULL)
 349                 goto error;
 350         esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm);
 351         esp->conf.padlen = 0;
 352         if (esp->conf.ivlen) {
 353                 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
 354                 if (unlikely(esp->conf.ivec == NULL))
 355                         goto error;
 356                 get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
 357         }
 358         if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len))
 359                 goto error;
 360         x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen;
 361         if (x->props.mode)
 362                 x->props.header_len += sizeof(struct ipv6hdr);
 363         x->data = esp;
 364         return 0;
 365
 366 error:
 367         x->data = esp;
 368         esp6_destroy(x);
 369         x->data = NULL;
 370         return -EINVAL;
 371 }
 372
 373 static struct xfrm_type esp6_type =
 374 {
 375         .description    = "ESP6",
 376         .owner          = THIS_MODULE,
 377         .proto          = IPPROTO_ESP,
 378         .init_state     = esp6_init_state,
 379         .destructor     = esp6_destroy,
 380         .get_max_size   = esp6_get_max_size,
 381         .input          = esp6_input,
 382         .output         = esp6_output
 383 };
 384
 385 static struct inet6_protocol esp6_protocol = {
 386         .handler        =       xfrm6_rcv,
 387         .err_handler    =       esp6_err,
 388         .flags          =       INET6_PROTO_NOPOLICY,
 389 };
 390
 391 static int __init esp6_init(void)
 392 {
 393         if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
 394                 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n");
 395                 return -EAGAIN;
 396         }
 397         if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
 398                 printk(KERN_INFO "ipv6 esp init: can't add protocol\n");
 399                 xfrm_unregister_type(&esp6_type, AF_INET6);
 400                 return -EAGAIN;
 401         }
 402
 403         return 0;
 404 }
 405
 406 static void __exit esp6_fini(void)
 407 {
 408         if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
 409                 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n");
 410         if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
 411                 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n");
 412 }
 413
 414 module_init(esp6_init);
 415 module_exit(esp6_fini);
 416
 417 MODULE_LICENSE("GPL");