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 <linux/spinlock.h>
  38 #include <net/icmp.h>
  39 #include <net/ipv6.h>
  40 #include <net/protocol.h>
  41 #include <linux/icmpv6.h>
  42
  43 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
  44 {
  45         int err;
  46         struct ipv6hdr *top_iph;
  47         struct ipv6_esp_hdr *esph;
  48         struct crypto_blkcipher *tfm;
  49         struct blkcipher_desc desc;
  50         struct sk_buff *trailer;
  51         int blksize;
  52         int clen;
  53         int alen;
  54         int nfrags;
  55         u8 *tail;
  56         struct esp_data *esp = x->data;
  57
  58         /* skb is pure payload to encrypt */
  59         err = -ENOMEM;
  60
  61         /* Round to block size */
  62         clen = skb->len;
  63
  64         alen = esp->auth.icv_trunc_len;
  65         tfm = esp->conf.tfm;
  66         desc.tfm = tfm;
  67         desc.flags = 0;
  68         blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
  69         clen = ALIGN(clen + 2, blksize);
  70         if (esp->conf.padlen)
  71                 clen = ALIGN(clen, esp->conf.padlen);
  72
  73         if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) {
  74                 goto error;
  75         }
  76
  77         /* Fill padding... */
  78         tail = skb_tail_pointer(trailer);
  79         do {
  80                 int i;
  81                 for (i=0; i<clen-skb->len - 2; i++)
  82                         tail[i] = i + 1;
  83         } while (0);
  84         tail[clen-skb->len - 2] = (clen - skb->len) - 2;
  85         pskb_put(skb, trailer, clen - skb->len);
  86
  87         skb_push(skb, -skb_network_offset(skb));
  88         top_iph = ipv6_hdr(skb);
  89         esph = (struct ipv6_esp_hdr *)skb_transport_header(skb);
  90         top_iph->payload_len = htons(skb->len + alen - sizeof(*top_iph));
  91         *(skb_tail_pointer(trailer) - 1) = *skb_mac_header(skb);
  92         *skb_mac_header(skb) = IPPROTO_ESP;
  93
  94         esph->spi = x->id.spi;
  95         esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq);
  96
  97         spin_lock_bh(&x->lock);
  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 unlock;
 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 unlock;
 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 unlock:
 136         spin_unlock_bh(&x->lock);
 137
 138 error:
 139         return err;
 140 }
 141
 142 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
 143 {
 144         struct ipv6hdr *iph;
 145         struct ipv6_esp_hdr *esph;
 146         struct esp_data *esp = x->data;
 147         struct crypto_blkcipher *tfm = esp->conf.tfm;
 148         struct blkcipher_desc desc = { .tfm = tfm };
 149         struct sk_buff *trailer;
 150         int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
 151         int alen = esp->auth.icv_trunc_len;
 152         int elen = skb->len - sizeof(struct ipv6_esp_hdr) - esp->conf.ivlen - alen;
 153         int hdr_len = skb_network_header_len(skb);
 154         int nfrags;
 155         int ret = 0;
 156
 157         if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) {
 158                 ret = -EINVAL;
 159                 goto out;
 160         }
 161
 162         if (elen <= 0 || (elen & (blksize-1))) {
 163                 ret = -EINVAL;
 164                 goto out;
 165         }
 166
 167         /* If integrity check is required, do this. */
 168         if (esp->auth.icv_full_len) {
 169                 u8 sum[alen];
 170
 171                 ret = esp_mac_digest(esp, skb, 0, skb->len - alen);
 172                 if (ret)
 173                         goto out;
 174
 175                 if (skb_copy_bits(skb, skb->len - alen, sum, alen))
 176                         BUG();
 177
 178                 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
 179                         x->stats.integrity_failed++;
 180                         ret = -EINVAL;
 181                         goto out;
 182                 }
 183         }
 184
 185         if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
 186                 ret = -EINVAL;
 187                 goto out;
 188         }
 189
 190         skb->ip_summed = CHECKSUM_NONE;
 191
 192         esph = (struct ipv6_esp_hdr*)skb->data;
 193         iph = ipv6_hdr(skb);
 194
 195         /* Get ivec. This can be wrong, check against another impls. */
 196         if (esp->conf.ivlen)
 197                 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
 198
 199         {
 200                 u8 nexthdr[2];
 201                 struct scatterlist *sg = &esp->sgbuf[0];
 202                 u8 padlen;
 203
 204                 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
 205                         sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
 206                         if (!sg) {
 207                                 ret = -ENOMEM;
 208                                 goto out;
 209                         }
 210                 }
 211                 skb_to_sgvec(skb, sg, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen, elen);
 212                 ret = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
 213                 if (unlikely(sg != &esp->sgbuf[0]))
 214                         kfree(sg);
 215                 if (unlikely(ret))
 216                         goto out;
 217
 218                 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
 219                         BUG();
 220
 221                 padlen = nexthdr[0];
 222                 if (padlen+2 >= elen) {
 223                         LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen);
 224                         ret = -EINVAL;
 225                         goto out;
 226                 }
 227                 /* ... check padding bits here. Silly. :-) */
 228
 229                 pskb_trim(skb, skb->len - alen - padlen - 2);
 230                 ret = nexthdr[1];
 231         }
 232
 233         __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen);
 234         skb_set_transport_header(skb, -hdr_len);
 235 out:
 236         return ret;
 237 }
 238
 239 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu)
 240 {
 241         struct esp_data *esp = x->data;
 242         u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
 243         u32 align = max_t(u32, blksize, esp->conf.padlen);
 244         u32 rem;
 245
 246         mtu -= x->props.header_len + esp->auth.icv_trunc_len;
 247         rem = mtu & (align - 1);
 248         mtu &= ~(align - 1);
 249
 250         if (x->props.mode != XFRM_MODE_TUNNEL) {
 251                 u32 padsize = ((blksize - 1) & 7) + 1;
 252                 mtu -= blksize - padsize;
 253                 mtu += min_t(u32, blksize - padsize, rem);
 254         }
 255
 256         return mtu - 2;
 257 }
 258
 259 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 260                      int type, int code, int offset, __be32 info)
 261 {
 262         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 263         struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset);
 264         struct xfrm_state *x;
 265
 266         if (type != ICMPV6_DEST_UNREACH &&
 267             type != ICMPV6_PKT_TOOBIG)
 268                 return;
 269
 270         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6);
 271         if (!x)
 272                 return;
 273         printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n",
 274                         ntohl(esph->spi), NIP6(iph->daddr));
 275         xfrm_state_put(x);
 276 }
 277
 278 static void esp6_destroy(struct xfrm_state *x)
 279 {
 280         struct esp_data *esp = x->data;
 281
 282         if (!esp)
 283                 return;
 284
 285         crypto_free_blkcipher(esp->conf.tfm);
 286         esp->conf.tfm = NULL;
 287         kfree(esp->conf.ivec);
 288         esp->conf.ivec = NULL;
 289         crypto_free_hash(esp->auth.tfm);
 290         esp->auth.tfm = NULL;
 291         kfree(esp->auth.work_icv);
 292         esp->auth.work_icv = NULL;
 293         kfree(esp);
 294 }
 295
 296 static int esp6_init_state(struct xfrm_state *x)
 297 {
 298         struct esp_data *esp = NULL;
 299         struct crypto_blkcipher *tfm;
 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                 hash = crypto_alloc_hash(x->aalg->alg_name, 0,
 316                                          CRYPTO_ALG_ASYNC);
 317                 if (IS_ERR(hash))
 318                         goto error;
 319
 320                 esp->auth.tfm = hash;
 321                 if (crypto_hash_setkey(hash, x->aalg->alg_key,
 322                                        (x->aalg->alg_key_len + 7) / 8))
 323                         goto error;
 324
 325                 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
 326                 BUG_ON(!aalg_desc);
 327
 328                 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
 329                     crypto_hash_digestsize(hash)) {
 330                         NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
 331                                  x->aalg->alg_name,
 332                                  crypto_hash_digestsize(hash),
 333                                  aalg_desc->uinfo.auth.icv_fullbits/8);
 334                         goto error;
 335                 }
 336
 337                 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
 338                 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
 339
 340                 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
 341                 if (!esp->auth.work_icv)
 342                         goto error;
 343         }
 344         tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
 345         if (IS_ERR(tfm))
 346                 goto error;
 347         esp->conf.tfm = tfm;
 348         esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
 349         esp->conf.padlen = 0;
 350         if (esp->conf.ivlen) {
 351                 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
 352                 if (unlikely(esp->conf.ivec == NULL))
 353                         goto error;
 354                 esp->conf.ivinitted = 0;
 355         }
 356         if (crypto_blkcipher_setkey(tfm, x->ealg->alg_key,
 357                                     (x->ealg->alg_key_len + 7) / 8))
 358                 goto error;
 359         x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen;
 360         if (x->props.mode == XFRM_MODE_TUNNEL)
 361                 x->props.header_len += sizeof(struct ipv6hdr);
 362         x->data = esp;
 363         return 0;
 364
 365 error:
 366         x->data = esp;
 367         esp6_destroy(x);
 368         x->data = NULL;
 369         return -EINVAL;
 370 }
 371
 372 static struct xfrm_type esp6_type =
 373 {
 374         .description    = "ESP6",
 375         .owner          = THIS_MODULE,
 376         .proto          = IPPROTO_ESP,
 377         .flags          = XFRM_TYPE_REPLAY_PROT,
 378         .init_state     = esp6_init_state,
 379         .destructor     = esp6_destroy,
 380         .get_mtu        = esp6_get_mtu,
 381         .input          = esp6_input,
 382         .output         = esp6_output,
 383         .hdr_offset     = xfrm6_find_1stfragopt,
 384 };
 385
 386 static struct inet6_protocol esp6_protocol = {
 387         .handler        =       xfrm6_rcv,
 388         .err_handler    =       esp6_err,
 389         .flags          =       INET6_PROTO_NOPOLICY,
 390 };
 391
 392 static int __init esp6_init(void)
 393 {
 394         if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
 395                 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n");
 396                 return -EAGAIN;
 397         }
 398         if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
 399                 printk(KERN_INFO "ipv6 esp init: can't add protocol\n");
 400                 xfrm_unregister_type(&esp6_type, AF_INET6);
 401                 return -EAGAIN;
 402         }
 403
 404         return 0;
 405 }
 406
 407 static void __exit esp6_fini(void)
 408 {
 409         if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
 410                 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n");
 411         if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
 412                 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n");
 413 }
 414
 415 module_init(esp6_init);
 416 module_exit(esp6_fini);
 417
 418 MODULE_LICENSE("GPL");
 419 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP);