net/ipv4/esp4.c

   1 #include <crypto/aead.h>
   2 #include <crypto/authenc.h>
   3 #include <linux/err.h>
   4 #include <linux/module.h>
   5 #include <net/ip.h>
   6 #include <net/xfrm.h>
   7 #include <net/esp.h>
   8 #include <linux/scatterlist.h>
   9 #include <linux/kernel.h>
  10 #include <linux/pfkeyv2.h>
  11 #include <linux/rtnetlink.h>
  12 #include <linux/slab.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/in6.h>
  15 #include <net/icmp.h>
  16 #include <net/protocol.h>
  17 #include <net/udp.h>
  18
  19 struct esp_skb_cb {
  20         struct xfrm_skb_cb xfrm;
  21         void *tmp;
  22 };
  23
  24 #define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0]))
  25
  26 static u32 esp4_get_mtu(struct xfrm_state *x, int mtu);
  27
  28 /*
  29  * Allocate an AEAD request structure with extra space for SG and IV.
  30  *
  31  * For alignment considerations the IV is placed at the front, followed
  32  * by the request and finally the SG list.
  33  *
  34  * TODO: Use spare space in skb for this where possible.
  35  */
  36 static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags)
  37 {
  38         unsigned int len;
  39
  40         len = crypto_aead_ivsize(aead);
  41         if (len) {
  42                 len += crypto_aead_alignmask(aead) &
  43                        ~(crypto_tfm_ctx_alignment() - 1);
  44                 len = ALIGN(len, crypto_tfm_ctx_alignment());
  45         }
  46
  47         len += sizeof(struct aead_givcrypt_request) + crypto_aead_reqsize(aead);
  48         len = ALIGN(len, __alignof__(struct scatterlist));
  49
  50         len += sizeof(struct scatterlist) * nfrags;
  51
  52         return kmalloc(len, GFP_ATOMIC);
  53 }
  54
  55 static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp)
  56 {
  57         return crypto_aead_ivsize(aead) ?
  58                PTR_ALIGN((u8 *)tmp, crypto_aead_alignmask(aead) + 1) : tmp;
  59 }
  60
  61 static inline struct aead_givcrypt_request *esp_tmp_givreq(
  62         struct crypto_aead *aead, u8 *iv)
  63 {
  64         struct aead_givcrypt_request *req;
  65
  66         req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
  67                                 crypto_tfm_ctx_alignment());
  68         aead_givcrypt_set_tfm(req, aead);
  69         return req;
  70 }
  71
  72 static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv)
  73 {
  74         struct aead_request *req;
  75
  76         req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
  77                                 crypto_tfm_ctx_alignment());
  78         aead_request_set_tfm(req, aead);
  79         return req;
  80 }
  81
  82 static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead,
  83                                              struct aead_request *req)
  84 {
  85         return (void *)ALIGN((unsigned long)(req + 1) +
  86                              crypto_aead_reqsize(aead),
  87                              __alignof__(struct scatterlist));
  88 }
  89
  90 static inline struct scatterlist *esp_givreq_sg(
  91         struct crypto_aead *aead, struct aead_givcrypt_request *req)
  92 {
  93         return (void *)ALIGN((unsigned long)(req + 1) +
  94                              crypto_aead_reqsize(aead),
  95                              __alignof__(struct scatterlist));
  96 }
  97
  98 static void esp_output_done(struct crypto_async_request *base, int err)
  99 {
 100         struct sk_buff *skb = base->data;
 101
 102         kfree(ESP_SKB_CB(skb)->tmp);
 103         xfrm_output_resume(skb, err);
 104 }
 105
 106 static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
 107 {
 108         int err;
 109         struct ip_esp_hdr *esph;
 110         struct crypto_aead *aead;
 111         struct aead_givcrypt_request *req;
 112         struct scatterlist *sg;
 113         struct scatterlist *asg;
 114         struct esp_data *esp;
 115         struct sk_buff *trailer;
 116         void *tmp;
 117         u8 *iv;
 118         u8 *tail;
 119         int blksize;
 120         int clen;
 121         int alen;
 122         int plen;
 123         int tfclen;
 124         int nfrags;
 125
 126         /* skb is pure payload to encrypt */
 127
 128         err = -ENOMEM;
 129
 130         esp = x->data;
 131         aead = esp->aead;
 132         alen = crypto_aead_authsize(aead);
 133
 134         tfclen = 0;
 135         if (x->tfcpad) {
 136                 struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb);
 137                 u32 padto;
 138
 139                 padto = min(x->tfcpad, esp4_get_mtu(x, dst->child_mtu_cached));
 140                 if (skb->len < padto)
 141                         tfclen = padto - skb->len;
 142         }
 143         blksize = ALIGN(crypto_aead_blocksize(aead), 4);
 144         clen = ALIGN(skb->len + 2 + tfclen, blksize);
 145         if (esp->padlen)
 146                 clen = ALIGN(clen, esp->padlen);
 147         plen = clen - skb->len - tfclen;
 148
 149         err = skb_cow_data(skb, tfclen + plen + alen, &trailer);
 150         if (err < 0)
 151                 goto error;
 152         nfrags = err;
 153
 154         tmp = esp_alloc_tmp(aead, nfrags + 1);
 155         if (!tmp)
 156                 goto error;
 157
 158         iv = esp_tmp_iv(aead, tmp);
 159         req = esp_tmp_givreq(aead, iv);
 160         asg = esp_givreq_sg(aead, req);
 161         sg = asg + 1;
 162
 163         /* Fill padding... */
 164         tail = skb_tail_pointer(trailer);
 165         if (tfclen) {
 166                 memset(tail, 0, tfclen);
 167                 tail += tfclen;
 168         }
 169         do {
 170                 int i;
 171                 for (i = 0; i < plen - 2; i++)
 172                         tail[i] = i + 1;
 173         } while (0);
 174         tail[plen - 2] = plen - 2;
 175         tail[plen - 1] = *skb_mac_header(skb);
 176         pskb_put(skb, trailer, clen - skb->len + alen);
 177
 178         skb_push(skb, -skb_network_offset(skb));
 179         esph = ip_esp_hdr(skb);
 180         *skb_mac_header(skb) = IPPROTO_ESP;
 181
 182         /* this is non-NULL only with UDP Encapsulation */
 183         if (x->encap) {
 184                 struct xfrm_encap_tmpl *encap = x->encap;
 185                 struct udphdr *uh;
 186                 __be32 *udpdata32;
 187                 __be16 sport, dport;
 188                 int encap_type;
 189
 190                 spin_lock_bh(&x->lock);
 191                 sport = encap->encap_sport;
 192                 dport = encap->encap_dport;
 193                 encap_type = encap->encap_type;
 194                 spin_unlock_bh(&x->lock);
 195
 196                 uh = (struct udphdr *)esph;
 197                 uh->source = sport;
 198                 uh->dest = dport;
 199                 uh->len = htons(skb->len - skb_transport_offset(skb));
 200                 uh->check = 0;
 201
 202                 switch (encap_type) {
 203                 default:
 204                 case UDP_ENCAP_ESPINUDP:
 205                         esph = (struct ip_esp_hdr *)(uh + 1);
 206                         break;
 207                 case UDP_ENCAP_ESPINUDP_NON_IKE:
 208                         udpdata32 = (__be32 *)(uh + 1);
 209                         udpdata32[0] = udpdata32[1] = 0;
 210                         esph = (struct ip_esp_hdr *)(udpdata32 + 2);
 211                         break;
 212                 }
 213
 214                 *skb_mac_header(skb) = IPPROTO_UDP;
 215         }
 216
 217         esph->spi = x->id.spi;
 218         esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output);
 219
 220         sg_init_table(sg, nfrags);
 221         skb_to_sgvec(skb, sg,
 222                      esph->enc_data + crypto_aead_ivsize(aead) - skb->data,
 223                      clen + alen);
 224         sg_init_one(asg, esph, sizeof(*esph));
 225
 226         aead_givcrypt_set_callback(req, 0, esp_output_done, skb);
 227         aead_givcrypt_set_crypt(req, sg, sg, clen, iv);
 228         aead_givcrypt_set_assoc(req, asg, sizeof(*esph));
 229         aead_givcrypt_set_giv(req, esph->enc_data,
 230                               XFRM_SKB_CB(skb)->seq.output);
 231
 232         ESP_SKB_CB(skb)->tmp = tmp;
 233         err = crypto_aead_givencrypt(req);
 234         if (err == -EINPROGRESS)
 235                 goto error;
 236
 237         if (err == -EBUSY)
 238                 err = NET_XMIT_DROP;
 239
 240         kfree(tmp);
 241
 242 error:
 243         return err;
 244 }
 245
 246 static int esp_input_done2(struct sk_buff *skb, int err)
 247 {
 248         struct iphdr *iph;
 249         struct xfrm_state *x = xfrm_input_state(skb);
 250         struct esp_data *esp = x->data;
 251         struct crypto_aead *aead = esp->aead;
 252         int alen = crypto_aead_authsize(aead);
 253         int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
 254         int elen = skb->len - hlen;
 255         int ihl;
 256         u8 nexthdr[2];
 257         int padlen;
 258
 259         kfree(ESP_SKB_CB(skb)->tmp);
 260
 261         if (unlikely(err))
 262                 goto out;
 263
 264         if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
 265                 BUG();
 266
 267         err = -EINVAL;
 268         padlen = nexthdr[0];
 269         if (padlen + 2 + alen >= elen)
 270                 goto out;
 271
 272         /* ... check padding bits here. Silly. :-) */
 273
 274         iph = ip_hdr(skb);
 275         ihl = iph->ihl * 4;
 276
 277         if (x->encap) {
 278                 struct xfrm_encap_tmpl *encap = x->encap;
 279                 struct udphdr *uh = (void *)(skb_network_header(skb) + ihl);
 280
 281                 /*
 282                  * 1) if the NAT-T peer's IP or port changed then
 283                  *    advertize the change to the keying daemon.
 284                  *    This is an inbound SA, so just compare
 285                  *    SRC ports.
 286                  */
 287                 if (iph->saddr != x->props.saddr.a4 ||
 288                     uh->source != encap->encap_sport) {
 289                         xfrm_address_t ipaddr;
 290
 291                         ipaddr.a4 = iph->saddr;
 292                         km_new_mapping(x, &ipaddr, uh->source);
 293
 294                         /* XXX: perhaps add an extra
 295                          * policy check here, to see
 296                          * if we should allow or
 297                          * reject a packet from a
 298                          * different source
 299                          * address/port.
 300                          */
 301                 }
 302
 303                 /*
 304                  * 2) ignore UDP/TCP checksums in case
 305                  *    of NAT-T in Transport Mode, or
 306                  *    perform other post-processing fixes
 307                  *    as per draft-ietf-ipsec-udp-encaps-06,
 308                  *    section 3.1.2
 309                  */
 310                 if (x->props.mode == XFRM_MODE_TRANSPORT)
 311                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 312         }
 313
 314         pskb_trim(skb, skb->len - alen - padlen - 2);
 315         __skb_pull(skb, hlen);
 316         skb_set_transport_header(skb, -ihl);
 317
 318         err = nexthdr[1];
 319
 320         /* RFC4303: Drop dummy packets without any error */
 321         if (err == IPPROTO_NONE)
 322                 err = -EINVAL;
 323
 324 out:
 325         return err;
 326 }
 327
 328 static void esp_input_done(struct crypto_async_request *base, int err)
 329 {
 330         struct sk_buff *skb = base->data;
 331
 332         xfrm_input_resume(skb, esp_input_done2(skb, err));
 333 }
 334
 335 /*
 336  * Note: detecting truncated vs. non-truncated authentication data is very
 337  * expensive, so we only support truncated data, which is the recommended
 338  * and common case.
 339  */
 340 static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
 341 {
 342         struct ip_esp_hdr *esph;
 343         struct esp_data *esp = x->data;
 344         struct crypto_aead *aead = esp->aead;
 345         struct aead_request *req;
 346         struct sk_buff *trailer;
 347         int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead);
 348         int nfrags;
 349         void *tmp;
 350         u8 *iv;
 351         struct scatterlist *sg;
 352         struct scatterlist *asg;
 353         int err = -EINVAL;
 354
 355         if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
 356                 goto out;
 357
 358         if (elen <= 0)
 359                 goto out;
 360
 361         if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
 362                 goto out;
 363         nfrags = err;
 364
 365         err = -ENOMEM;
 366         tmp = esp_alloc_tmp(aead, nfrags + 1);
 367         if (!tmp)
 368                 goto out;
 369
 370         ESP_SKB_CB(skb)->tmp = tmp;
 371         iv = esp_tmp_iv(aead, tmp);
 372         req = esp_tmp_req(aead, iv);
 373         asg = esp_req_sg(aead, req);
 374         sg = asg + 1;
 375
 376         skb->ip_summed = CHECKSUM_NONE;
 377
 378         esph = (struct ip_esp_hdr *)skb->data;
 379
 380         /* Get ivec. This can be wrong, check against another impls. */
 381         iv = esph->enc_data;
 382
 383         sg_init_table(sg, nfrags);
 384         skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen);
 385         sg_init_one(asg, esph, sizeof(*esph));
 386
 387         aead_request_set_callback(req, 0, esp_input_done, skb);
 388         aead_request_set_crypt(req, sg, sg, elen, iv);
 389         aead_request_set_assoc(req, asg, sizeof(*esph));
 390
 391         err = crypto_aead_decrypt(req);
 392         if (err == -EINPROGRESS)
 393                 goto out;
 394
 395         err = esp_input_done2(skb, err);
 396
 397 out:
 398         return err;
 399 }
 400
 401 static u32 esp4_get_mtu(struct xfrm_state *x, int mtu)
 402 {
 403         struct esp_data *esp = x->data;
 404         u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4);
 405         u32 align = max_t(u32, blksize, esp->padlen);
 406         u32 rem;
 407
 408         mtu -= x->props.header_len + crypto_aead_authsize(esp->aead);
 409         rem = mtu & (align - 1);
 410         mtu &= ~(align - 1);
 411
 412         switch (x->props.mode) {
 413         case XFRM_MODE_TUNNEL:
 414                 break;
 415         default:
 416         case XFRM_MODE_TRANSPORT:
 417                 /* The worst case */
 418                 mtu -= blksize - 4;
 419                 mtu += min_t(u32, blksize - 4, rem);
 420                 break;
 421         case XFRM_MODE_BEET:
 422                 /* The worst case. */
 423                 mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem);
 424                 break;
 425         }
 426
 427         return mtu - 2;
 428 }
 429
 430 static void esp4_err(struct sk_buff *skb, u32 info)
 431 {
 432         struct net *net = dev_net(skb->dev);
 433         struct iphdr *iph = (struct iphdr *)skb->data;
 434         struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data+(iph->ihl<<2));
 435         struct xfrm_state *x;
 436
 437         if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
 438             icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
 439                 return;
 440
 441         x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET);
 442         if (!x)
 443                 return;
 444         NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
 445                  ntohl(esph->spi), ntohl(iph->daddr));
 446         xfrm_state_put(x);
 447 }
 448
 449 static void esp_destroy(struct xfrm_state *x)
 450 {
 451         struct esp_data *esp = x->data;
 452
 453         if (!esp)
 454                 return;
 455
 456         crypto_free_aead(esp->aead);
 457         kfree(esp);
 458 }
 459
 460 static int esp_init_aead(struct xfrm_state *x)
 461 {
 462         struct esp_data *esp = x->data;
 463         struct crypto_aead *aead;
 464         int err;
 465
 466         aead = crypto_alloc_aead(x->aead->alg_name, 0, 0);
 467         err = PTR_ERR(aead);
 468         if (IS_ERR(aead))
 469                 goto error;
 470
 471         esp->aead = aead;
 472
 473         err = crypto_aead_setkey(aead, x->aead->alg_key,
 474                                  (x->aead->alg_key_len + 7) / 8);
 475         if (err)
 476                 goto error;
 477
 478         err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8);
 479         if (err)
 480                 goto error;
 481
 482 error:
 483         return err;
 484 }
 485
 486 static int esp_init_authenc(struct xfrm_state *x)
 487 {
 488         struct esp_data *esp = x->data;
 489         struct crypto_aead *aead;
 490         struct crypto_authenc_key_param *param;
 491         struct rtattr *rta;
 492         char *key;
 493         char *p;
 494         char authenc_name[CRYPTO_MAX_ALG_NAME];
 495         unsigned int keylen;
 496         int err;
 497
 498         err = -EINVAL;
 499         if (x->ealg == NULL)
 500                 goto error;
 501
 502         err = -ENAMETOOLONG;
 503         if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, "authenc(%s,%s)",
 504                      x->aalg ? x->aalg->alg_name : "digest_null",
 505                      x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
 506                 goto error;
 507
 508         aead = crypto_alloc_aead(authenc_name, 0, 0);
 509         err = PTR_ERR(aead);
 510         if (IS_ERR(aead))
 511                 goto error;
 512
 513         esp->aead = aead;
 514
 515         keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) +
 516                  (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param));
 517         err = -ENOMEM;
 518         key = kmalloc(keylen, GFP_KERNEL);
 519         if (!key)
 520                 goto error;
 521
 522         p = key;
 523         rta = (void *)p;
 524         rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM;
 525         rta->rta_len = RTA_LENGTH(sizeof(*param));
 526         param = RTA_DATA(rta);
 527         p += RTA_SPACE(sizeof(*param));
 528
 529         if (x->aalg) {
 530                 struct xfrm_algo_desc *aalg_desc;
 531
 532                 memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8);
 533                 p += (x->aalg->alg_key_len + 7) / 8;
 534
 535                 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
 536                 BUG_ON(!aalg_desc);
 537
 538                 err = -EINVAL;
 539                 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
 540                     crypto_aead_authsize(aead)) {
 541                         NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
 542                                  x->aalg->alg_name,
 543                                  crypto_aead_authsize(aead),
 544                                  aalg_desc->uinfo.auth.icv_fullbits/8);
 545                         goto free_key;
 546                 }
 547
 548                 err = crypto_aead_setauthsize(
 549                         aead, x->aalg->alg_trunc_len / 8);
 550                 if (err)
 551                         goto free_key;
 552         }
 553
 554         param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8);
 555         memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8);
 556
 557         err = crypto_aead_setkey(aead, key, keylen);
 558
 559 free_key:
 560         kfree(key);
 561
 562 error:
 563         return err;
 564 }
 565
 566 static int esp_init_state(struct xfrm_state *x)
 567 {
 568         struct esp_data *esp;
 569         struct crypto_aead *aead;
 570         u32 align;
 571         int err;
 572
 573         esp = kzalloc(sizeof(*esp), GFP_KERNEL);
 574         if (esp == NULL)
 575                 return -ENOMEM;
 576
 577         x->data = esp;
 578
 579         if (x->aead)
 580                 err = esp_init_aead(x);
 581         else
 582                 err = esp_init_authenc(x);
 583
 584         if (err)
 585                 goto error;
 586
 587         aead = esp->aead;
 588
 589         esp->padlen = 0;
 590
 591         x->props.header_len = sizeof(struct ip_esp_hdr) +
 592                               crypto_aead_ivsize(aead);
 593         if (x->props.mode == XFRM_MODE_TUNNEL)
 594                 x->props.header_len += sizeof(struct iphdr);
 595         else if (x->props.mode == XFRM_MODE_BEET && x->sel.family != AF_INET6)
 596                 x->props.header_len += IPV4_BEET_PHMAXLEN;
 597         if (x->encap) {
 598                 struct xfrm_encap_tmpl *encap = x->encap;
 599
 600                 switch (encap->encap_type) {
 601                 default:
 602                         goto error;
 603                 case UDP_ENCAP_ESPINUDP:
 604                         x->props.header_len += sizeof(struct udphdr);
 605                         break;
 606                 case UDP_ENCAP_ESPINUDP_NON_IKE:
 607                         x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
 608                         break;
 609                 }
 610         }
 611
 612         align = ALIGN(crypto_aead_blocksize(aead), 4);
 613         if (esp->padlen)
 614                 align = max_t(u32, align, esp->padlen);
 615         x->props.trailer_len = align + 1 + crypto_aead_authsize(esp->aead);
 616
 617 error:
 618         return err;
 619 }
 620
 621 static const struct xfrm_type esp_type =
 622 {
 623         .description    = "ESP4",
 624         .owner          = THIS_MODULE,
 625         .proto          = IPPROTO_ESP,
 626         .flags          = XFRM_TYPE_REPLAY_PROT,
 627         .init_state     = esp_init_state,
 628         .destructor     = esp_destroy,
 629         .get_mtu        = esp4_get_mtu,
 630         .input          = esp_input,
 631         .output         = esp_output
 632 };
 633
 634 static const struct net_protocol esp4_protocol = {
 635         .handler        =       xfrm4_rcv,
 636         .err_handler    =       esp4_err,
 637         .no_policy      =       1,
 638         .netns_ok       =       1,
 639 };
 640
 641 static int __init esp4_init(void)
 642 {
 643         if (xfrm_register_type(&esp_type, AF_INET) < 0) {
 644                 printk(KERN_INFO "ip esp init: can't add xfrm type\n");
 645                 return -EAGAIN;
 646         }
 647         if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) {
 648                 printk(KERN_INFO "ip esp init: can't add protocol\n");
 649                 xfrm_unregister_type(&esp_type, AF_INET);
 650                 return -EAGAIN;
 651         }
 652         return 0;
 653 }
 654
 655 static void __exit esp4_fini(void)
 656 {
 657         if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0)
 658                 printk(KERN_INFO "ip esp close: can't remove protocol\n");
 659         if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
 660                 printk(KERN_INFO "ip esp close: can't remove xfrm type\n");
 661 }
 662
 663 module_init(esp4_init);
 664 module_exit(esp4_fini);
 665 MODULE_LICENSE("GPL");
 666 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP);