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/module.h>
  28 #include <net/ip.h>
  29 #include <net/xfrm.h>
  30 #include <net/esp.h>
  31 #include <asm/scatterlist.h>
  32 #include <linux/crypto.h>
  33 #include <linux/kernel.h>
  34 #include <linux/pfkeyv2.h>
  35 #include <linux/random.h>
  36 #include <net/icmp.h>
  37 #include <net/ipv6.h>
  38 #include <net/protocol.h>
  39 #include <linux/icmpv6.h>
  40
  41 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
  42 {
  43         int err;
  44         int hdr_len;
  45         struct ipv6hdr *top_iph;
  46         struct ipv6_esp_hdr *esph;
  47         struct crypto_tfm *tfm;
  48         struct esp_data *esp;
  49         struct sk_buff *trailer;
  50         int blksize;
  51         int clen;
  52         int alen;
  53         int nfrags;
  54
  55         esp = x->data;
  56         hdr_len = skb->h.raw - skb->data +
  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         blksize = ALIGN(crypto_tfm_alg_blocksize(tfm), 4);
  71         clen = ALIGN(clen + 2, blksize);
  72         if (esp->conf.padlen)
  73                 clen = ALIGN(clen, esp->conf.padlen);
  74
  75         if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) {
  76                 goto error;
  77         }
  78
  79         /* Fill padding... */
  80         do {
  81                 int i;
  82                 for (i=0; i<clen-skb->len - 2; i++)
  83                         *(u8*)(trailer->tail + i) = i+1;
  84         } while (0);
  85         *(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2;
  86         pskb_put(skb, trailer, clen - skb->len);
  87
  88         top_iph = (struct ipv6hdr *)__skb_push(skb, hdr_len);
  89         esph = (struct ipv6_esp_hdr *)skb->h.raw;
  90         top_iph->payload_len = htons(skb->len + alen - sizeof(*top_iph));
  91         *(u8*)(trailer->tail - 1) = *skb->nh.raw;
  92         *skb->nh.raw = IPPROTO_ESP;
  93
  94         esph->spi = x->id.spi;
  95         esph->seq_no = htonl(++x->replay.oseq);
  96         xfrm_aevent_doreplay(x);
  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 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         int ret = 0;
 145
 146         if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) {
 147                 ret = -EINVAL;
 148                 goto out;
 149         }
 150
 151         if (elen <= 0 || (elen & (blksize-1))) {
 152                 ret = -EINVAL;
 153                 goto out;
 154         }
 155
 156         /* If integrity check is required, do this. */
 157         if (esp->auth.icv_full_len) {
 158                 u8 sum[esp->auth.icv_full_len];
 159                 u8 sum1[alen];
 160
 161                 esp->auth.icv(esp, skb, 0, skb->len-alen, sum);
 162
 163                 if (skb_copy_bits(skb, skb->len-alen, sum1, alen))
 164                         BUG();
 165
 166                 if (unlikely(memcmp(sum, sum1, alen))) {
 167                         x->stats.integrity_failed++;
 168                         ret = -EINVAL;
 169                         goto out;
 170                 }
 171         }
 172
 173         if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
 174                 ret = -EINVAL;
 175                 goto out;
 176         }
 177
 178         skb->ip_summed = CHECKSUM_NONE;
 179
 180         esph = (struct ipv6_esp_hdr*)skb->data;
 181         iph = skb->nh.ipv6h;
 182
 183         /* Get ivec. This can be wrong, check against another impls. */
 184         if (esp->conf.ivlen)
 185                 crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm));
 186
 187         {
 188                 u8 nexthdr[2];
 189                 struct scatterlist *sg = &esp->sgbuf[0];
 190                 u8 padlen;
 191
 192                 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
 193                         sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
 194                         if (!sg) {
 195                                 ret = -ENOMEM;
 196                                 goto out;
 197                         }
 198                 }
 199                 skb_to_sgvec(skb, sg, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen, elen);
 200                 crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen);
 201                 if (unlikely(sg != &esp->sgbuf[0]))
 202                         kfree(sg);
 203
 204                 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
 205                         BUG();
 206
 207                 padlen = nexthdr[0];
 208                 if (padlen+2 >= elen) {
 209                         LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen);
 210                         ret = -EINVAL;
 211                         goto out;
 212                 }
 213                 /* ... check padding bits here. Silly. :-) */
 214
 215                 pskb_trim(skb, skb->len - alen - padlen - 2);
 216                 ret = nexthdr[1];
 217         }
 218
 219         skb->h.raw = __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen) - hdr_len;
 220
 221 out:
 222         return ret;
 223 }
 224
 225 static u32 esp6_get_max_size(struct xfrm_state *x, int mtu)
 226 {
 227         struct esp_data *esp = x->data;
 228         u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4);
 229
 230         if (x->props.mode) {
 231                 mtu = ALIGN(mtu + 2, blksize);
 232         } else {
 233                 /* The worst case. */
 234                 u32 padsize = ((blksize - 1) & 7) + 1;
 235                 mtu = ALIGN(mtu + 2, padsize) + blksize - padsize;
 236         }
 237         if (esp->conf.padlen)
 238                 mtu = ALIGN(mtu, esp->conf.padlen);
 239
 240         return mtu + x->props.header_len + esp->auth.icv_trunc_len;
 241 }
 242
 243 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 244                      int type, int code, int offset, __u32 info)
 245 {
 246         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 247         struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset);
 248         struct xfrm_state *x;
 249
 250         if (type != ICMPV6_DEST_UNREACH &&
 251             type != ICMPV6_PKT_TOOBIG)
 252                 return;
 253
 254         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6);
 255         if (!x)
 256                 return;
 257         printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n",
 258                         ntohl(esph->spi), NIP6(iph->daddr));
 259         xfrm_state_put(x);
 260 }
 261
 262 static void esp6_destroy(struct xfrm_state *x)
 263 {
 264         struct esp_data *esp = x->data;
 265
 266         if (!esp)
 267                 return;
 268
 269         crypto_free_tfm(esp->conf.tfm);
 270         esp->conf.tfm = NULL;
 271         kfree(esp->conf.ivec);
 272         esp->conf.ivec = NULL;
 273         crypto_free_tfm(esp->auth.tfm);
 274         esp->auth.tfm = NULL;
 275         kfree(esp->auth.work_icv);
 276         esp->auth.work_icv = NULL;
 277         kfree(esp);
 278 }
 279
 280 static int esp6_init_state(struct xfrm_state *x)
 281 {
 282         struct esp_data *esp = NULL;
 283
 284         /* null auth and encryption can have zero length keys */
 285         if (x->aalg) {
 286                 if (x->aalg->alg_key_len > 512)
 287                         goto error;
 288         }
 289         if (x->ealg == NULL)
 290                 goto error;
 291
 292         if (x->encap)
 293                 goto error;
 294
 295         esp = kzalloc(sizeof(*esp), GFP_KERNEL);
 296         if (esp == NULL)
 297                 return -ENOMEM;
 298
 299         if (x->aalg) {
 300                 struct xfrm_algo_desc *aalg_desc;
 301
 302                 esp->auth.key = x->aalg->alg_key;
 303                 esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
 304                 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
 305                 if (esp->auth.tfm == NULL)
 306                         goto error;
 307                 esp->auth.icv = esp_hmac_digest;
 308
 309                 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
 310                 BUG_ON(!aalg_desc);
 311
 312                 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
 313                         crypto_tfm_alg_digestsize(esp->auth.tfm)) {
 314                                 printk(KERN_INFO "ESP: %s digestsize %u != %hu\n",
 315                                         x->aalg->alg_name,
 316                                         crypto_tfm_alg_digestsize(esp->auth.tfm),
 317                                         aalg_desc->uinfo.auth.icv_fullbits/8);
 318                                 goto error;
 319                 }
 320
 321                 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
 322                 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
 323
 324                 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
 325                 if (!esp->auth.work_icv)
 326                         goto error;
 327         }
 328         esp->conf.key = x->ealg->alg_key;
 329         esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
 330         if (x->props.ealgo == SADB_EALG_NULL)
 331                 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB);
 332         else
 333                 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC);
 334         if (esp->conf.tfm == NULL)
 335                 goto error;
 336         esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm);
 337         esp->conf.padlen = 0;
 338         if (esp->conf.ivlen) {
 339                 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
 340                 if (unlikely(esp->conf.ivec == NULL))
 341                         goto error;
 342                 get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
 343         }
 344         if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len))
 345                 goto error;
 346         x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen;
 347         if (x->props.mode)
 348                 x->props.header_len += sizeof(struct ipv6hdr);
 349         x->data = esp;
 350         return 0;
 351
 352 error:
 353         x->data = esp;
 354         esp6_destroy(x);
 355         x->data = NULL;
 356         return -EINVAL;
 357 }
 358
 359 static struct xfrm_type esp6_type =
 360 {
 361         .description    = "ESP6",
 362         .owner          = THIS_MODULE,
 363         .proto          = IPPROTO_ESP,
 364         .init_state     = esp6_init_state,
 365         .destructor     = esp6_destroy,
 366         .get_max_size   = esp6_get_max_size,
 367         .input          = esp6_input,
 368         .output         = esp6_output
 369 };
 370
 371 static struct inet6_protocol esp6_protocol = {
 372         .handler        =       xfrm6_rcv,
 373         .err_handler    =       esp6_err,
 374         .flags          =       INET6_PROTO_NOPOLICY,
 375 };
 376
 377 static int __init esp6_init(void)
 378 {
 379         if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
 380                 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n");
 381                 return -EAGAIN;
 382         }
 383         if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
 384                 printk(KERN_INFO "ipv6 esp init: can't add protocol\n");
 385                 xfrm_unregister_type(&esp6_type, AF_INET6);
 386                 return -EAGAIN;
 387         }
 388
 389         return 0;
 390 }
 391
 392 static void __exit esp6_fini(void)
 393 {
 394         if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
 395                 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n");
 396         if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
 397                 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n");
 398 }
 399
 400 module_init(esp6_init);
 401 module_exit(esp6_fini);
 402
 403 MODULE_LICENSE("GPL");