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