net/ipv6/ah6.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/ah.c.
  25  */
  26
  27 #include <crypto/hash.h>
  28 #include <linux/module.h>
  29 #include <linux/slab.h>
  30 #include <net/ip.h>
  31 #include <net/ah.h>
  32 #include <linux/crypto.h>
  33 #include <linux/pfkeyv2.h>
  34 #include <linux/string.h>
  35 #include <linux/scatterlist.h>
  36 #include <net/icmp.h>
  37 #include <net/ipv6.h>
  38 #include <net/protocol.h>
  39 #include <net/xfrm.h>
  40
  41 #define IPV6HDR_BASELEN 8
  42
  43 struct tmp_ext {
  44 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
  45                 struct in6_addr saddr;
  46 #endif
  47                 struct in6_addr daddr;
  48                 char hdrs[0];
  49 };
  50
  51 struct ah_skb_cb {
  52         struct xfrm_skb_cb xfrm;
  53         void *tmp;
  54 };
  55
  56 #define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0]))
  57
  58 static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags,
  59                           unsigned int size)
  60 {
  61         unsigned int len;
  62
  63         len = size + crypto_ahash_digestsize(ahash) +
  64               (crypto_ahash_alignmask(ahash) &
  65                ~(crypto_tfm_ctx_alignment() - 1));
  66
  67         len = ALIGN(len, crypto_tfm_ctx_alignment());
  68
  69         len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash);
  70         len = ALIGN(len, __alignof__(struct scatterlist));
  71
  72         len += sizeof(struct scatterlist) * nfrags;
  73
  74         return kmalloc(len, GFP_ATOMIC);
  75 }
  76
  77 static inline struct tmp_ext *ah_tmp_ext(void *base)
  78 {
  79         return base + IPV6HDR_BASELEN;
  80 }
  81
  82 static inline u8 *ah_tmp_auth(u8 *tmp, unsigned int offset)
  83 {
  84         return tmp + offset;
  85 }
  86
  87 static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp,
  88                              unsigned int offset)
  89 {
  90         return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1);
  91 }
  92
  93 static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash,
  94                                                u8 *icv)
  95 {
  96         struct ahash_request *req;
  97
  98         req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash),
  99                                 crypto_tfm_ctx_alignment());
 100
 101         ahash_request_set_tfm(req, ahash);
 102
 103         return req;
 104 }
 105
 106 static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash,
 107                                              struct ahash_request *req)
 108 {
 109         return (void *)ALIGN((unsigned long)(req + 1) +
 110                              crypto_ahash_reqsize(ahash),
 111                              __alignof__(struct scatterlist));
 112 }
 113
 114 static int zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr)
 115 {
 116         u8 *opt = (u8 *)opthdr;
 117         int len = ipv6_optlen(opthdr);
 118         int off = 0;
 119         int optlen = 0;
 120
 121         off += 2;
 122         len -= 2;
 123
 124         while (len > 0) {
 125
 126                 switch (opt[off]) {
 127
 128                 case IPV6_TLV_PAD0:
 129                         optlen = 1;
 130                         break;
 131                 default:
 132                         if (len < 2)
 133                                 goto bad;
 134                         optlen = opt[off+1]+2;
 135                         if (len < optlen)
 136                                 goto bad;
 137                         if (opt[off] & 0x20)
 138                                 memset(&opt[off+2], 0, opt[off+1]);
 139                         break;
 140                 }
 141
 142                 off += optlen;
 143                 len -= optlen;
 144         }
 145         if (len == 0)
 146                 return 1;
 147
 148 bad:
 149         return 0;
 150 }
 151
 152 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 153 /**
 154  *      ipv6_rearrange_destopt - rearrange IPv6 destination options header
 155  *      @iph: IPv6 header
 156  *      @destopt: destionation options header
 157  */
 158 static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt)
 159 {
 160         u8 *opt = (u8 *)destopt;
 161         int len = ipv6_optlen(destopt);
 162         int off = 0;
 163         int optlen = 0;
 164
 165         off += 2;
 166         len -= 2;
 167
 168         while (len > 0) {
 169
 170                 switch (opt[off]) {
 171
 172                 case IPV6_TLV_PAD0:
 173                         optlen = 1;
 174                         break;
 175                 default:
 176                         if (len < 2)
 177                                 goto bad;
 178                         optlen = opt[off+1]+2;
 179                         if (len < optlen)
 180                                 goto bad;
 181
 182                         /* Rearrange the source address in @iph and the
 183                          * addresses in home address option for final source.
 184                          * See 11.3.2 of RFC 3775 for details.
 185                          */
 186                         if (opt[off] == IPV6_TLV_HAO) {
 187                                 struct in6_addr final_addr;
 188                                 struct ipv6_destopt_hao *hao;
 189
 190                                 hao = (struct ipv6_destopt_hao *)&opt[off];
 191                                 if (hao->length != sizeof(hao->addr)) {
 192                                         if (net_ratelimit())
 193                                                 printk(KERN_WARNING "destopt hao: invalid header length: %u\n", hao->length);
 194                                         goto bad;
 195                                 }
 196                                 ipv6_addr_copy(&final_addr, &hao->addr);
 197                                 ipv6_addr_copy(&hao->addr, &iph->saddr);
 198                                 ipv6_addr_copy(&iph->saddr, &final_addr);
 199                         }
 200                         break;
 201                 }
 202
 203                 off += optlen;
 204                 len -= optlen;
 205         }
 206         /* Note: ok if len == 0 */
 207 bad:
 208         return;
 209 }
 210 #else
 211 static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt) {}
 212 #endif
 213
 214 /**
 215  *      ipv6_rearrange_rthdr - rearrange IPv6 routing header
 216  *      @iph: IPv6 header
 217  *      @rthdr: routing header
 218  *
 219  *      Rearrange the destination address in @iph and the addresses in @rthdr
 220  *      so that they appear in the order they will at the final destination.
 221  *      See Appendix A2 of RFC 2402 for details.
 222  */
 223 static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr)
 224 {
 225         int segments, segments_left;
 226         struct in6_addr *addrs;
 227         struct in6_addr final_addr;
 228
 229         segments_left = rthdr->segments_left;
 230         if (segments_left == 0)
 231                 return;
 232         rthdr->segments_left = 0;
 233
 234         /* The value of rthdr->hdrlen has been verified either by the system
 235          * call if it is locally generated, or by ipv6_rthdr_rcv() for incoming
 236          * packets.  So we can assume that it is even and that segments is
 237          * greater than or equal to segments_left.
 238          *
 239          * For the same reason we can assume that this option is of type 0.
 240          */
 241         segments = rthdr->hdrlen >> 1;
 242
 243         addrs = ((struct rt0_hdr *)rthdr)->addr;
 244         ipv6_addr_copy(&final_addr, addrs + segments - 1);
 245
 246         addrs += segments - segments_left;
 247         memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs));
 248
 249         ipv6_addr_copy(addrs, &iph->daddr);
 250         ipv6_addr_copy(&iph->daddr, &final_addr);
 251 }
 252
 253 static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len, int dir)
 254 {
 255         union {
 256                 struct ipv6hdr *iph;
 257                 struct ipv6_opt_hdr *opth;
 258                 struct ipv6_rt_hdr *rth;
 259                 char *raw;
 260         } exthdr = { .iph = iph };
 261         char *end = exthdr.raw + len;
 262         int nexthdr = iph->nexthdr;
 263
 264         exthdr.iph++;
 265
 266         while (exthdr.raw < end) {
 267                 switch (nexthdr) {
 268                 case NEXTHDR_DEST:
 269                         if (dir == XFRM_POLICY_OUT)
 270                                 ipv6_rearrange_destopt(iph, exthdr.opth);
 271                 case NEXTHDR_HOP:
 272                         if (!zero_out_mutable_opts(exthdr.opth)) {
 273                                 LIMIT_NETDEBUG(
 274                                         KERN_WARNING "overrun %sopts\n",
 275                                         nexthdr == NEXTHDR_HOP ?
 276                                                 "hop" : "dest");
 277                                 return -EINVAL;
 278                         }
 279                         break;
 280
 281                 case NEXTHDR_ROUTING:
 282                         ipv6_rearrange_rthdr(iph, exthdr.rth);
 283                         break;
 284
 285                 default :
 286                         return 0;
 287                 }
 288
 289                 nexthdr = exthdr.opth->nexthdr;
 290                 exthdr.raw += ipv6_optlen(exthdr.opth);
 291         }
 292
 293         return 0;
 294 }
 295
 296 static void ah6_output_done(struct crypto_async_request *base, int err)
 297 {
 298         int extlen;
 299         u8 *iph_base;
 300         u8 *icv;
 301         struct sk_buff *skb = base->data;
 302         struct xfrm_state *x = skb_dst(skb)->xfrm;
 303         struct ah_data *ahp = x->data;
 304         struct ipv6hdr *top_iph = ipv6_hdr(skb);
 305         struct ip_auth_hdr *ah = ip_auth_hdr(skb);
 306         struct tmp_ext *iph_ext;
 307
 308         extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
 309         if (extlen)
 310                 extlen += sizeof(*iph_ext);
 311
 312         iph_base = AH_SKB_CB(skb)->tmp;
 313         iph_ext = ah_tmp_ext(iph_base);
 314         icv = ah_tmp_icv(ahp->ahash, iph_ext, extlen);
 315
 316         memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
 317         memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
 318
 319         if (extlen) {
 320 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 321                 memcpy(&top_iph->saddr, iph_ext, extlen);
 322 #else
 323                 memcpy(&top_iph->daddr, iph_ext, extlen);
 324 #endif
 325         }
 326
 327         err = ah->nexthdr;
 328
 329         kfree(AH_SKB_CB(skb)->tmp);
 330         xfrm_output_resume(skb, err);
 331 }
 332
 333 static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
 334 {
 335         int err;
 336         int nfrags;
 337         int extlen;
 338         u8 *iph_base;
 339         u8 *icv;
 340         u8 nexthdr;
 341         struct sk_buff *trailer;
 342         struct crypto_ahash *ahash;
 343         struct ahash_request *req;
 344         struct scatterlist *sg;
 345         struct ipv6hdr *top_iph;
 346         struct ip_auth_hdr *ah;
 347         struct ah_data *ahp;
 348         struct tmp_ext *iph_ext;
 349
 350         ahp = x->data;
 351         ahash = ahp->ahash;
 352
 353         if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
 354                 goto out;
 355         nfrags = err;
 356
 357         skb_push(skb, -skb_network_offset(skb));
 358         extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
 359         if (extlen)
 360                 extlen += sizeof(*iph_ext);
 361
 362         err = -ENOMEM;
 363         iph_base = ah_alloc_tmp(ahash, nfrags, IPV6HDR_BASELEN + extlen);
 364         if (!iph_base)
 365                 goto out;
 366
 367         iph_ext = ah_tmp_ext(iph_base);
 368         icv = ah_tmp_icv(ahash, iph_ext, extlen);
 369         req = ah_tmp_req(ahash, icv);
 370         sg = ah_req_sg(ahash, req);
 371
 372         ah = ip_auth_hdr(skb);
 373         memset(ah->auth_data, 0, ahp->icv_trunc_len);
 374
 375         top_iph = ipv6_hdr(skb);
 376         top_iph->payload_len = htons(skb->len - sizeof(*top_iph));
 377
 378         nexthdr = *skb_mac_header(skb);
 379         *skb_mac_header(skb) = IPPROTO_AH;
 380
 381         /* When there are no extension headers, we only need to save the first
 382          * 8 bytes of the base IP header.
 383          */
 384         memcpy(iph_base, top_iph, IPV6HDR_BASELEN);
 385
 386         if (extlen) {
 387 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 388                 memcpy(iph_ext, &top_iph->saddr, extlen);
 389 #else
 390                 memcpy(iph_ext, &top_iph->daddr, extlen);
 391 #endif
 392                 err = ipv6_clear_mutable_options(top_iph,
 393                                                  extlen - sizeof(*iph_ext) +
 394                                                  sizeof(*top_iph),
 395                                                  XFRM_POLICY_OUT);
 396                 if (err)
 397                         goto out_free;
 398         }
 399
 400         ah->nexthdr = nexthdr;
 401
 402         top_iph->priority    = 0;
 403         top_iph->flow_lbl[0] = 0;
 404         top_iph->flow_lbl[1] = 0;
 405         top_iph->flow_lbl[2] = 0;
 406         top_iph->hop_limit   = 0;
 407
 408         ah->hdrlen  = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
 409
 410         ah->reserved = 0;
 411         ah->spi = x->id.spi;
 412         ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
 413
 414         sg_init_table(sg, nfrags);
 415         skb_to_sgvec(skb, sg, 0, skb->len);
 416
 417         ahash_request_set_crypt(req, sg, icv, skb->len);
 418         ahash_request_set_callback(req, 0, ah6_output_done, skb);
 419
 420         AH_SKB_CB(skb)->tmp = iph_base;
 421
 422         err = crypto_ahash_digest(req);
 423         if (err) {
 424                 if (err == -EINPROGRESS)
 425                         goto out;
 426
 427                 if (err == -EBUSY)
 428                         err = NET_XMIT_DROP;
 429                 goto out_free;
 430         }
 431
 432         memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
 433         memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
 434
 435         if (extlen) {
 436 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 437                 memcpy(&top_iph->saddr, iph_ext, extlen);
 438 #else
 439                 memcpy(&top_iph->daddr, iph_ext, extlen);
 440 #endif
 441         }
 442
 443 out_free:
 444         kfree(iph_base);
 445 out:
 446         return err;
 447 }
 448
 449 static void ah6_input_done(struct crypto_async_request *base, int err)
 450 {
 451         u8 *auth_data;
 452         u8 *icv;
 453         u8 *work_iph;
 454         struct sk_buff *skb = base->data;
 455         struct xfrm_state *x = xfrm_input_state(skb);
 456         struct ah_data *ahp = x->data;
 457         struct ip_auth_hdr *ah = ip_auth_hdr(skb);
 458         int hdr_len = skb_network_header_len(skb);
 459         int ah_hlen = (ah->hdrlen + 2) << 2;
 460
 461         work_iph = AH_SKB_CB(skb)->tmp;
 462         auth_data = ah_tmp_auth(work_iph, hdr_len);
 463         icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);
 464
 465         err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
 466         if (err)
 467                 goto out;
 468
 469         skb->network_header += ah_hlen;
 470         memcpy(skb_network_header(skb), work_iph, hdr_len);
 471         __skb_pull(skb, ah_hlen + hdr_len);
 472         skb_set_transport_header(skb, -hdr_len);
 473
 474         err = ah->nexthdr;
 475 out:
 476         kfree(AH_SKB_CB(skb)->tmp);
 477         xfrm_input_resume(skb, err);
 478 }
 479
 480
 481
 482 static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
 483 {
 484         /*
 485          * Before process AH
 486          * [IPv6][Ext1][Ext2][AH][Dest][Payload]
 487          * |<-------------->| hdr_len
 488          *
 489          * To erase AH:
 490          * Keeping copy of cleared headers. After AH processing,
 491          * Moving the pointer of skb->network_header by using skb_pull as long
 492          * as AH header length. Then copy back the copy as long as hdr_len
 493          * If destination header following AH exists, copy it into after [Ext2].
 494          *
 495          * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
 496          * There is offset of AH before IPv6 header after the process.
 497          */
 498
 499         u8 *auth_data;
 500         u8 *icv;
 501         u8 *work_iph;
 502         struct sk_buff *trailer;
 503         struct crypto_ahash *ahash;
 504         struct ahash_request *req;
 505         struct scatterlist *sg;
 506         struct ip_auth_hdr *ah;
 507         struct ipv6hdr *ip6h;
 508         struct ah_data *ahp;
 509         u16 hdr_len;
 510         u16 ah_hlen;
 511         int nexthdr;
 512         int nfrags;
 513         int err = -ENOMEM;
 514
 515         if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
 516                 goto out;
 517
 518         /* We are going to _remove_ AH header to keep sockets happy,
 519          * so... Later this can change. */
 520         if (skb_cloned(skb) &&
 521             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 522                 goto out;
 523
 524         skb->ip_summed = CHECKSUM_NONE;
 525
 526         hdr_len = skb_network_header_len(skb);
 527         ah = (struct ip_auth_hdr *)skb->data;
 528         ahp = x->data;
 529         ahash = ahp->ahash;
 530
 531         nexthdr = ah->nexthdr;
 532         ah_hlen = (ah->hdrlen + 2) << 2;
 533
 534         if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
 535             ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
 536                 goto out;
 537
 538         if (!pskb_may_pull(skb, ah_hlen))
 539                 goto out;
 540
 541
 542         if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
 543                 goto out;
 544         nfrags = err;
 545
 546         ah = (struct ip_auth_hdr *)skb->data;
 547         ip6h = ipv6_hdr(skb);
 548
 549         skb_push(skb, hdr_len);
 550
 551         work_iph = ah_alloc_tmp(ahash, nfrags, hdr_len + ahp->icv_trunc_len);
 552         if (!work_iph)
 553                 goto out;
 554
 555         auth_data = ah_tmp_auth(work_iph, hdr_len);
 556         icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len);
 557         req = ah_tmp_req(ahash, icv);
 558         sg = ah_req_sg(ahash, req);
 559
 560         memcpy(work_iph, ip6h, hdr_len);
 561         memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
 562         memset(ah->auth_data, 0, ahp->icv_trunc_len);
 563
 564         if (ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN))
 565                 goto out_free;
 566
 567         ip6h->priority    = 0;
 568         ip6h->flow_lbl[0] = 0;
 569         ip6h->flow_lbl[1] = 0;
 570         ip6h->flow_lbl[2] = 0;
 571         ip6h->hop_limit   = 0;
 572
 573         sg_init_table(sg, nfrags);
 574         skb_to_sgvec(skb, sg, 0, skb->len);
 575
 576         ahash_request_set_crypt(req, sg, icv, skb->len);
 577         ahash_request_set_callback(req, 0, ah6_input_done, skb);
 578
 579         AH_SKB_CB(skb)->tmp = work_iph;
 580
 581         err = crypto_ahash_digest(req);
 582         if (err) {
 583                 if (err == -EINPROGRESS)
 584                         goto out;
 585
 586                 if (err == -EBUSY)
 587                         err = NET_XMIT_DROP;
 588                 goto out_free;
 589         }
 590
 591         err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
 592         if (err)
 593                 goto out_free;
 594
 595         skb->network_header += ah_hlen;
 596         memcpy(skb_network_header(skb), work_iph, hdr_len);
 597         skb->transport_header = skb->network_header;
 598         __skb_pull(skb, ah_hlen + hdr_len);
 599
 600         err = nexthdr;
 601
 602 out_free:
 603         kfree(work_iph);
 604 out:
 605         return err;
 606 }
 607
 608 static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 609                     u8 type, u8 code, int offset, __be32 info)
 610 {
 611         struct net *net = dev_net(skb->dev);
 612         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 613         struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+offset);
 614         struct xfrm_state *x;
 615
 616         if (type != ICMPV6_DEST_UNREACH &&
 617             type != ICMPV6_PKT_TOOBIG)
 618                 return;
 619
 620         x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
 621         if (!x)
 622                 return;
 623
 624         NETDEBUG(KERN_DEBUG "pmtu discovery on SA AH/%08x/%pI6\n",
 625                  ntohl(ah->spi), &iph->daddr);
 626
 627         xfrm_state_put(x);
 628 }
 629
 630 static int ah6_init_state(struct xfrm_state *x)
 631 {
 632         struct ah_data *ahp = NULL;
 633         struct xfrm_algo_desc *aalg_desc;
 634         struct crypto_ahash *ahash;
 635
 636         if (!x->aalg)
 637                 goto error;
 638
 639         if (x->encap)
 640                 goto error;
 641
 642         ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
 643         if (ahp == NULL)
 644                 return -ENOMEM;
 645
 646         ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
 647         if (IS_ERR(ahash))
 648                 goto error;
 649
 650         ahp->ahash = ahash;
 651         if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
 652                                (x->aalg->alg_key_len + 7) / 8))
 653                 goto error;
 654
 655         /*
 656          * Lookup the algorithm description maintained by xfrm_algo,
 657          * verify crypto transform properties, and store information
 658          * we need for AH processing.  This lookup cannot fail here
 659          * after a successful crypto_alloc_hash().
 660          */
 661         aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
 662         BUG_ON(!aalg_desc);
 663
 664         if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
 665             crypto_ahash_digestsize(ahash)) {
 666                 printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
 667                        x->aalg->alg_name, crypto_ahash_digestsize(ahash),
 668                        aalg_desc->uinfo.auth.icv_fullbits/8);
 669                 goto error;
 670         }
 671
 672         ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
 673         ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
 674
 675         BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
 676
 677         x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
 678                                           ahp->icv_trunc_len);
 679         switch (x->props.mode) {
 680         case XFRM_MODE_BEET:
 681         case XFRM_MODE_TRANSPORT:
 682                 break;
 683         case XFRM_MODE_TUNNEL:
 684                 x->props.header_len += sizeof(struct ipv6hdr);
 685                 break;
 686         default:
 687                 goto error;
 688         }
 689         x->data = ahp;
 690
 691         return 0;
 692
 693 error:
 694         if (ahp) {
 695                 crypto_free_ahash(ahp->ahash);
 696                 kfree(ahp);
 697         }
 698         return -EINVAL;
 699 }
 700
 701 static void ah6_destroy(struct xfrm_state *x)
 702 {
 703         struct ah_data *ahp = x->data;
 704
 705         if (!ahp)
 706                 return;
 707
 708         crypto_free_ahash(ahp->ahash);
 709         kfree(ahp);
 710 }
 711
 712 static const struct xfrm_type ah6_type =
 713 {
 714         .description    = "AH6",
 715         .owner          = THIS_MODULE,
 716         .proto          = IPPROTO_AH,
 717         .flags          = XFRM_TYPE_REPLAY_PROT,
 718         .init_state     = ah6_init_state,
 719         .destructor     = ah6_destroy,
 720         .input          = ah6_input,
 721         .output         = ah6_output,
 722         .hdr_offset     = xfrm6_find_1stfragopt,
 723 };
 724
 725 static const struct inet6_protocol ah6_protocol = {
 726         .handler        =       xfrm6_rcv,
 727         .err_handler    =       ah6_err,
 728         .flags          =       INET6_PROTO_NOPOLICY,
 729 };
 730
 731 static int __init ah6_init(void)
 732 {
 733         if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
 734                 printk(KERN_INFO "ipv6 ah init: can't add xfrm type\n");
 735                 return -EAGAIN;
 736         }
 737
 738         if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) {
 739                 printk(KERN_INFO "ipv6 ah init: can't add protocol\n");
 740                 xfrm_unregister_type(&ah6_type, AF_INET6);
 741                 return -EAGAIN;
 742         }
 743
 744         return 0;
 745 }
 746
 747 static void __exit ah6_fini(void)
 748 {
 749         if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0)
 750                 printk(KERN_INFO "ipv6 ah close: can't remove protocol\n");
 751
 752         if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
 753                 printk(KERN_INFO "ipv6 ah close: can't remove xfrm type\n");
 754
 755 }
 756
 757 module_init(ah6_init);
 758 module_exit(ah6_fini);
 759
 760 MODULE_LICENSE("GPL");
 761 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_AH);