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         struct esp_data *esp = x->data;
  55         int hdr_len = (skb_transport_offset(skb) +
  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         desc.tfm = tfm;
  70         desc.flags = 0;
  71         blksize = ALIGN(crypto_blkcipher_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_transport_header(skb);
  91         top_iph->payload_len = htons(skb->len + alen - sizeof(*top_iph));
  92         *(u8 *)(trailer->tail - 1) = *skb_network_header(skb);
  93         *skb_network_header(skb) = IPPROTO_ESP;
  94
  95         esph->spi = x->id.spi;
  96         esph->seq_no = htonl(++x->replay.oseq);
  97         xfrm_aevent_doreplay(x);
  98
  99         if (esp->conf.ivlen) {
 100                 if (unlikely(!esp->conf.ivinitted)) {
 101                         get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
 102                         esp->conf.ivinitted = 1;
 103                 }
 104                 crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
 105         }
 106
 107         do {
 108                 struct scatterlist *sg = &esp->sgbuf[0];
 109
 110                 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
 111                         sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
 112                         if (!sg)
 113                                 goto error;
 114                 }
 115                 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
 116                 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
 117                 if (unlikely(sg != &esp->sgbuf[0]))
 118                         kfree(sg);
 119         } while (0);
 120
 121         if (unlikely(err))
 122                 goto error;
 123
 124         if (esp->conf.ivlen) {
 125                 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
 126                 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
 127         }
 128
 129         if (esp->auth.icv_full_len) {
 130                 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
 131                                      sizeof(*esph) + esp->conf.ivlen + clen);
 132                 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
 133         }
 134
 135 error:
 136         return err;
 137 }
 138
 139 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
 140 {
 141         struct ipv6hdr *iph;
 142         struct ipv6_esp_hdr *esph;
 143         struct esp_data *esp = x->data;
 144         struct crypto_blkcipher *tfm = esp->conf.tfm;
 145         struct blkcipher_desc desc = { .tfm = tfm };
 146         struct sk_buff *trailer;
 147         int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
 148         int alen = esp->auth.icv_trunc_len;
 149         int elen = skb->len - sizeof(struct ipv6_esp_hdr) - esp->conf.ivlen - alen;
 150         int hdr_len = skb_network_header_len(skb);
 151         int nfrags;
 152         int ret = 0;
 153
 154         if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) {
 155                 ret = -EINVAL;
 156                 goto out;
 157         }
 158
 159         if (elen <= 0 || (elen & (blksize-1))) {
 160                 ret = -EINVAL;
 161                 goto out;
 162         }
 163
 164         /* If integrity check is required, do this. */
 165         if (esp->auth.icv_full_len) {
 166                 u8 sum[alen];
 167
 168                 ret = esp_mac_digest(esp, skb, 0, skb->len - alen);
 169                 if (ret)
 170                         goto out;
 171
 172                 if (skb_copy_bits(skb, skb->len - alen, sum, alen))
 173                         BUG();
 174
 175                 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
 176                         x->stats.integrity_failed++;
 177                         ret = -EINVAL;
 178                         goto out;
 179                 }
 180         }
 181
 182         if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
 183                 ret = -EINVAL;
 184                 goto out;
 185         }
 186
 187         skb->ip_summed = CHECKSUM_NONE;
 188
 189         esph = (struct ipv6_esp_hdr*)skb->data;
 190         iph = ipv6_hdr(skb);
 191
 192         /* Get ivec. This can be wrong, check against another impls. */
 193         if (esp->conf.ivlen)
 194                 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
 195
 196         {
 197                 u8 nexthdr[2];
 198                 struct scatterlist *sg = &esp->sgbuf[0];
 199                 u8 padlen;
 200
 201                 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
 202                         sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
 203                         if (!sg) {
 204                                 ret = -ENOMEM;
 205                                 goto out;
 206                         }
 207                 }
 208                 skb_to_sgvec(skb, sg, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen, elen);
 209                 ret = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
 210                 if (unlikely(sg != &esp->sgbuf[0]))
 211                         kfree(sg);
 212                 if (unlikely(ret))
 213                         goto out;
 214
 215                 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
 216                         BUG();
 217
 218                 padlen = nexthdr[0];
 219                 if (padlen+2 >= elen) {
 220                         LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen);
 221                         ret = -EINVAL;
 222                         goto out;
 223                 }
 224                 /* ... check padding bits here. Silly. :-) */
 225
 226                 pskb_trim(skb, skb->len - alen - padlen - 2);
 227                 ret = nexthdr[1];
 228         }
 229
 230         __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen);
 231         skb_set_transport_header(skb, -hdr_len);
 232 out:
 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 = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
 240
 241         if (x->props.mode == XFRM_MODE_TUNNEL) {
 242                 mtu = ALIGN(mtu + 2, blksize);
 243         } else {
 244                 /* The worst case. */
 245                 u32 padsize = ((blksize - 1) & 7) + 1;
 246                 mtu = ALIGN(mtu + 2, padsize) + blksize - padsize;
 247         }
 248         if (esp->conf.padlen)
 249                 mtu = ALIGN(mtu, esp->conf.padlen);
 250
 251         return mtu + x->props.header_len + esp->auth.icv_trunc_len;
 252 }
 253
 254 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 255                      int type, int code, int offset, __be32 info)
 256 {
 257         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 258         struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset);
 259         struct xfrm_state *x;
 260
 261         if (type != ICMPV6_DEST_UNREACH &&
 262             type != ICMPV6_PKT_TOOBIG)
 263                 return;
 264
 265         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6);
 266         if (!x)
 267                 return;
 268         printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\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         crypto_free_blkcipher(esp->conf.tfm);
 281         esp->conf.tfm = NULL;
 282         kfree(esp->conf.ivec);
 283         esp->conf.ivec = NULL;
 284         crypto_free_hash(esp->auth.tfm);
 285         esp->auth.tfm = NULL;
 286         kfree(esp->auth.work_icv);
 287         esp->auth.work_icv = NULL;
 288         kfree(esp);
 289 }
 290
 291 static int esp6_init_state(struct xfrm_state *x)
 292 {
 293         struct esp_data *esp = NULL;
 294         struct crypto_blkcipher *tfm;
 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 = kzalloc(sizeof(*esp), GFP_KERNEL);
 308         if (esp == NULL)
 309                 return -ENOMEM;
 310
 311         if (x->aalg) {
 312                 struct xfrm_algo_desc *aalg_desc;
 313                 struct crypto_hash *hash;
 314
 315                 esp->auth.key = x->aalg->alg_key;
 316                 esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
 317                 hash = crypto_alloc_hash(x->aalg->alg_name, 0,
 318                                          CRYPTO_ALG_ASYNC);
 319                 if (IS_ERR(hash))
 320                         goto error;
 321
 322                 esp->auth.tfm = hash;
 323                 if (crypto_hash_setkey(hash, esp->auth.key, esp->auth.key_len))
 324                         goto error;
 325
 326                 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
 327                 BUG_ON(!aalg_desc);
 328
 329                 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
 330                     crypto_hash_digestsize(hash)) {
 331                         NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
 332                                  x->aalg->alg_name,
 333                                  crypto_hash_digestsize(hash),
 334                                  aalg_desc->uinfo.auth.icv_fullbits/8);
 335                         goto error;
 336                 }
 337
 338                 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
 339                 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
 340
 341                 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
 342                 if (!esp->auth.work_icv)
 343                         goto error;
 344         }
 345         esp->conf.key = x->ealg->alg_key;
 346         esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
 347         tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
 348         if (IS_ERR(tfm))
 349                 goto error;
 350         esp->conf.tfm = tfm;
 351         esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
 352         esp->conf.padlen = 0;
 353         if (esp->conf.ivlen) {
 354                 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
 355                 if (unlikely(esp->conf.ivec == NULL))
 356                         goto error;
 357                 esp->conf.ivinitted = 0;
 358         }
 359         if (crypto_blkcipher_setkey(tfm, esp->conf.key, esp->conf.key_len))
 360                 goto error;
 361         x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen;
 362         if (x->props.mode == XFRM_MODE_TUNNEL)
 363                 x->props.header_len += sizeof(struct ipv6hdr);
 364         x->data = esp;
 365         return 0;
 366
 367 error:
 368         x->data = esp;
 369         esp6_destroy(x);
 370         x->data = NULL;
 371         return -EINVAL;
 372 }
 373
 374 static struct xfrm_type esp6_type =
 375 {
 376         .description    = "ESP6",
 377         .owner          = THIS_MODULE,
 378         .proto          = IPPROTO_ESP,
 379         .init_state     = esp6_init_state,
 380         .destructor     = esp6_destroy,
 381         .get_max_size   = esp6_get_max_size,
 382         .input          = esp6_input,
 383         .output         = esp6_output,
 384         .hdr_offset     = xfrm6_find_1stfragopt,
 385 };
 386
 387 static struct inet6_protocol esp6_protocol = {
 388         .handler        =       xfrm6_rcv,
 389         .err_handler    =       esp6_err,
 390         .flags          =       INET6_PROTO_NOPOLICY,
 391 };
 392
 393 static int __init esp6_init(void)
 394 {
 395         if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
 396                 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n");
 397                 return -EAGAIN;
 398         }
 399         if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
 400                 printk(KERN_INFO "ipv6 esp init: can't add protocol\n");
 401                 xfrm_unregister_type(&esp6_type, AF_INET6);
 402                 return -EAGAIN;
 403         }
 404
 405         return 0;
 406 }
 407
 408 static void __exit esp6_fini(void)
 409 {
 410         if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
 411                 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n");
 412         if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
 413                 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n");
 414 }
 415
 416 module_init(esp6_init);
 417 module_exit(esp6_fini);
 418
 419 MODULE_LICENSE("GPL");