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         xfrm_aevent_doreplay(x);
  98
  99         if (esp->conf.ivlen)
 100                 crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
 101
 102         do {
 103                 struct scatterlist *sg = &esp->sgbuf[0];
 104
 105                 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
 106                         sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
 107                         if (!sg)
 108                                 goto error;
 109                 }
 110                 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
 111                 crypto_cipher_encrypt(tfm, sg, sg, clen);
 112                 if (unlikely(sg != &esp->sgbuf[0]))
 113                         kfree(sg);
 114         } while (0);
 115
 116         if (esp->conf.ivlen) {
 117                 memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
 118                 crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
 119         }
 120
 121         if (esp->auth.icv_full_len) {
 122                 esp->auth.icv(esp, skb, (u8*)esph-skb->data,
 123                         sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen+clen, trailer->tail);
 124                 pskb_put(skb, trailer, alen);
 125         }
 126
 127         err = 0;
 128
 129 error:
 130         return err;
 131 }
 132
 133 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
 134 {
 135         struct ipv6hdr *iph;
 136         struct ipv6_esp_hdr *esph;
 137         struct esp_data *esp = x->data;
 138         struct sk_buff *trailer;
 139         int blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4);
 140         int alen = esp->auth.icv_trunc_len;
 141         int elen = skb->len - sizeof(struct ipv6_esp_hdr) - esp->conf.ivlen - alen;
 142
 143         int hdr_len = skb->h.raw - skb->nh.raw;
 144         int nfrags;
 145         unsigned char *tmp_hdr = NULL;
 146         int ret = 0;
 147
 148         if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) {
 149                 ret = -EINVAL;
 150                 goto out_nofree;
 151         }
 152
 153         if (elen <= 0 || (elen & (blksize-1))) {
 154                 ret = -EINVAL;
 155                 goto out_nofree;
 156         }
 157
 158         tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
 159         if (!tmp_hdr) {
 160                 ret = -ENOMEM;
 161                 goto out_nofree;
 162         }
 163         memcpy(tmp_hdr, skb->nh.raw, hdr_len);
 164
 165         /* If integrity check is required, do this. */
 166         if (esp->auth.icv_full_len) {
 167                 u8 sum[esp->auth.icv_full_len];
 168                 u8 sum1[alen];
 169
 170                 esp->auth.icv(esp, skb, 0, skb->len-alen, sum);
 171
 172                 if (skb_copy_bits(skb, skb->len-alen, sum1, alen))
 173                         BUG();
 174
 175                 if (unlikely(memcmp(sum, sum1, 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 = skb->nh.ipv6h;
 191
 192         /* Get ivec. This can be wrong, check against another impls. */
 193         if (esp->conf.ivlen)
 194                 crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm));
 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                 crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen);
 210                 if (unlikely(sg != &esp->sgbuf[0]))
 211                         kfree(sg);
 212
 213                 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
 214                         BUG();
 215
 216                 padlen = nexthdr[0];
 217                 if (padlen+2 >= elen) {
 218                         LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen);
 219                         ret = -EINVAL;
 220                         goto out;
 221                 }
 222                 /* ... check padding bits here. Silly. :-) */
 223
 224                 pskb_trim(skb, skb->len - alen - padlen - 2);
 225                 skb->h.raw = skb_pull(skb, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen);
 226                 skb->nh.raw += sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen;
 227                 memcpy(skb->nh.raw, tmp_hdr, hdr_len);
 228                 skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 229                 ret = nexthdr[1];
 230         }
 231
 232 out:
 233         kfree(tmp_hdr);
 234 out_nofree:
 235         return ret;
 236 }
 237
 238 static u32 esp6_get_max_size(struct xfrm_state *x, int mtu)
 239 {
 240         struct esp_data *esp = x->data;
 241         u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4);
 242
 243         if (x->props.mode) {
 244                 mtu = ALIGN(mtu + 2, blksize);
 245         } else {
 246                 /* The worst case. */
 247                 u32 padsize = ((blksize - 1) & 7) + 1;
 248                 mtu = ALIGN(mtu + 2, padsize) + blksize - padsize;
 249         }
 250         if (esp->conf.padlen)
 251                 mtu = ALIGN(mtu, esp->conf.padlen);
 252
 253         return mtu + x->props.header_len + esp->auth.icv_trunc_len;
 254 }
 255
 256 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 257                      int type, int code, int offset, __u32 info)
 258 {
 259         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 260         struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset);
 261         struct xfrm_state *x;
 262
 263         if (type != ICMPV6_DEST_UNREACH &&
 264             type != ICMPV6_PKT_TOOBIG)
 265                 return;
 266
 267         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6);
 268         if (!x)
 269                 return;
 270         printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n",
 271                         ntohl(esph->spi), NIP6(iph->daddr));
 272         xfrm_state_put(x);
 273 }
 274
 275 static void esp6_destroy(struct xfrm_state *x)
 276 {
 277         struct esp_data *esp = x->data;
 278
 279         if (!esp)
 280                 return;
 281
 282         crypto_free_tfm(esp->conf.tfm);
 283         esp->conf.tfm = NULL;
 284         kfree(esp->conf.ivec);
 285         esp->conf.ivec = NULL;
 286         crypto_free_tfm(esp->auth.tfm);
 287         esp->auth.tfm = NULL;
 288         kfree(esp->auth.work_icv);
 289         esp->auth.work_icv = NULL;
 290         kfree(esp);
 291 }
 292
 293 static int esp6_init_state(struct xfrm_state *x)
 294 {
 295         struct esp_data *esp = NULL;
 296
 297         /* null auth and encryption can have zero length keys */
 298         if (x->aalg) {
 299                 if (x->aalg->alg_key_len > 512)
 300                         goto error;
 301         }
 302         if (x->ealg == NULL)
 303                 goto error;
 304
 305         if (x->encap)
 306                 goto error;
 307
 308         esp = kzalloc(sizeof(*esp), GFP_KERNEL);
 309         if (esp == NULL)
 310                 return -ENOMEM;
 311
 312         if (x->aalg) {
 313                 struct xfrm_algo_desc *aalg_desc;
 314
 315                 esp->auth.key = x->aalg->alg_key;
 316                 esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
 317                 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
 318                 if (esp->auth.tfm == NULL)
 319                         goto error;
 320                 esp->auth.icv = esp_hmac_digest;
 321
 322                 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
 323                 BUG_ON(!aalg_desc);
 324
 325                 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
 326                         crypto_tfm_alg_digestsize(esp->auth.tfm)) {
 327                                 printk(KERN_INFO "ESP: %s digestsize %u != %hu\n",
 328                                         x->aalg->alg_name,
 329                                         crypto_tfm_alg_digestsize(esp->auth.tfm),
 330                                         aalg_desc->uinfo.auth.icv_fullbits/8);
 331                                 goto error;
 332                 }
 333
 334                 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
 335                 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
 336
 337                 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
 338                 if (!esp->auth.work_icv)
 339                         goto error;
 340         }
 341         esp->conf.key = x->ealg->alg_key;
 342         esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
 343         if (x->props.ealgo == SADB_EALG_NULL)
 344                 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB);
 345         else
 346                 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC);
 347         if (esp->conf.tfm == NULL)
 348                 goto error;
 349         esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm);
 350         esp->conf.padlen = 0;
 351         if (esp->conf.ivlen) {
 352                 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
 353                 if (unlikely(esp->conf.ivec == NULL))
 354                         goto error;
 355                 get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
 356         }
 357         if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len))
 358                 goto error;
 359         x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen;
 360         if (x->props.mode)
 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         .init_state     = esp6_init_state,
 378         .destructor     = esp6_destroy,
 379         .get_max_size   = esp6_get_max_size,
 380         .input          = esp6_input,
 381         .output         = esp6_output
 382 };
 383
 384 static struct inet6_protocol esp6_protocol = {
 385         .handler        =       xfrm6_rcv,
 386         .err_handler    =       esp6_err,
 387         .flags          =       INET6_PROTO_NOPOLICY,
 388 };
 389
 390 static int __init esp6_init(void)
 391 {
 392         if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
 393                 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n");
 394                 return -EAGAIN;
 395         }
 396         if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
 397                 printk(KERN_INFO "ipv6 esp init: can't add protocol\n");
 398                 xfrm_unregister_type(&esp6_type, AF_INET6);
 399                 return -EAGAIN;
 400         }
 401
 402         return 0;
 403 }
 404
 405 static void __exit esp6_fini(void)
 406 {
 407         if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
 408                 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n");
 409         if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
 410                 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n");
 411 }
 412
 413 module_init(esp6_init);
 414 module_exit(esp6_fini);
 415
 416 MODULE_LICENSE("GPL");