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, see <http://www.gnu.org/licenses/>.
  16  *
  17  * Authors
  18  *
  19  *      Mitsuru KANDA @USAGI       : IPv6 Support
  20  *      Kazunori MIYAZAWA @USAGI   :
  21  *      Kunihiro Ishiguro <kunihiro@ipinfusion.com>
  22  *
  23  *      This file is derived from net/ipv4/ah.c.
  24  */
  25
  26 #define pr_fmt(fmt) "IPv6: " fmt
  27
  28 #include <crypto/hash.h>
  29 #include <linux/module.h>
  30 #include <linux/slab.h>
  31 #include <net/ip.h>
  32 #include <net/ah.h>
  33 #include <linux/crypto.h>
  34 #include <linux/pfkeyv2.h>
  35 #include <linux/string.h>
  36 #include <linux/scatterlist.h>
  37 #include <net/ip6_route.h>
  38 #include <net/icmp.h>
  39 #include <net/ipv6.h>
  40 #include <net/protocol.h>
  41 #include <net/xfrm.h>
  42
  43 #define IPV6HDR_BASELEN 8
  44
  45 struct tmp_ext {
  46 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  47                 struct in6_addr saddr;
  48 #endif
  49                 struct in6_addr daddr;
  50                 char hdrs[0];
  51 };
  52
  53 struct ah_skb_cb {
  54         struct xfrm_skb_cb xfrm;
  55         void *tmp;
  56 };
  57
  58 #define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0]))
  59
  60 static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags,
  61                           unsigned int size)
  62 {
  63         unsigned int len;
  64
  65         len = size + crypto_ahash_digestsize(ahash) +
  66               (crypto_ahash_alignmask(ahash) &
  67                ~(crypto_tfm_ctx_alignment() - 1));
  68
  69         len = ALIGN(len, crypto_tfm_ctx_alignment());
  70
  71         len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash);
  72         len = ALIGN(len, __alignof__(struct scatterlist));
  73
  74         len += sizeof(struct scatterlist) * nfrags;
  75
  76         return kmalloc(len, GFP_ATOMIC);
  77 }
  78
  79 static inline struct tmp_ext *ah_tmp_ext(void *base)
  80 {
  81         return base + IPV6HDR_BASELEN;
  82 }
  83
  84 static inline u8 *ah_tmp_auth(u8 *tmp, unsigned int offset)
  85 {
  86         return tmp + offset;
  87 }
  88
  89 static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp,
  90                              unsigned int offset)
  91 {
  92         return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1);
  93 }
  94
  95 static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash,
  96                                                u8 *icv)
  97 {
  98         struct ahash_request *req;
  99
 100         req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash),
 101                                 crypto_tfm_ctx_alignment());
 102
 103         ahash_request_set_tfm(req, ahash);
 104
 105         return req;
 106 }
 107
 108 static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash,
 109                                              struct ahash_request *req)
 110 {
 111         return (void *)ALIGN((unsigned long)(req + 1) +
 112                              crypto_ahash_reqsize(ahash),
 113                              __alignof__(struct scatterlist));
 114 }
 115
 116 static bool zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr)
 117 {
 118         u8 *opt = (u8 *)opthdr;
 119         int len = ipv6_optlen(opthdr);
 120         int off = 0;
 121         int optlen = 0;
 122
 123         off += 2;
 124         len -= 2;
 125
 126         while (len > 0) {
 127
 128                 switch (opt[off]) {
 129
 130                 case IPV6_TLV_PAD1:
 131                         optlen = 1;
 132                         break;
 133                 default:
 134                         if (len < 2)
 135                                 goto bad;
 136                         optlen = opt[off+1]+2;
 137                         if (len < optlen)
 138                                 goto bad;
 139                         if (opt[off] & 0x20)
 140                                 memset(&opt[off+2], 0, opt[off+1]);
 141                         break;
 142                 }
 143
 144                 off += optlen;
 145                 len -= optlen;
 146         }
 147         if (len == 0)
 148                 return true;
 149
 150 bad:
 151         return false;
 152 }
 153
 154 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 155 /**
 156  *      ipv6_rearrange_destopt - rearrange IPv6 destination options header
 157  *      @iph: IPv6 header
 158  *      @destopt: destionation options header
 159  */
 160 static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt)
 161 {
 162         u8 *opt = (u8 *)destopt;
 163         int len = ipv6_optlen(destopt);
 164         int off = 0;
 165         int optlen = 0;
 166
 167         off += 2;
 168         len -= 2;
 169
 170         while (len > 0) {
 171
 172                 switch (opt[off]) {
 173
 174                 case IPV6_TLV_PAD1:
 175                         optlen = 1;
 176                         break;
 177                 default:
 178                         if (len < 2)
 179                                 goto bad;
 180                         optlen = opt[off+1]+2;
 181                         if (len < optlen)
 182                                 goto bad;
 183
 184                         /* Rearrange the source address in @iph and the
 185                          * addresses in home address option for final source.
 186                          * See 11.3.2 of RFC 3775 for details.
 187                          */
 188                         if (opt[off] == IPV6_TLV_HAO) {
 189                                 struct in6_addr final_addr;
 190                                 struct ipv6_destopt_hao *hao;
 191
 192                                 hao = (struct ipv6_destopt_hao *)&opt[off];
 193                                 if (hao->length != sizeof(hao->addr)) {
 194                                         net_warn_ratelimited("destopt hao: invalid header length: %u\n",
 195                                                              hao->length);
 196                                         goto bad;
 197                                 }
 198                                 final_addr = hao->addr;
 199                                 hao->addr = iph->saddr;
 200                                 iph->saddr = final_addr;
 201                         }
 202                         break;
 203                 }
 204
 205                 off += optlen;
 206                 len -= optlen;
 207         }
 208         /* Note: ok if len == 0 */
 209 bad:
 210         return;
 211 }
 212 #else
 213 static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt) {}
 214 #endif
 215
 216 /**
 217  *      ipv6_rearrange_rthdr - rearrange IPv6 routing header
 218  *      @iph: IPv6 header
 219  *      @rthdr: routing header
 220  *
 221  *      Rearrange the destination address in @iph and the addresses in @rthdr
 222  *      so that they appear in the order they will at the final destination.
 223  *      See Appendix A2 of RFC 2402 for details.
 224  */
 225 static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr)
 226 {
 227         int segments, segments_left;
 228         struct in6_addr *addrs;
 229         struct in6_addr final_addr;
 230
 231         segments_left = rthdr->segments_left;
 232         if (segments_left == 0)
 233                 return;
 234         rthdr->segments_left = 0;
 235
 236         /* The value of rthdr->hdrlen has been verified either by the system
 237          * call if it is locally generated, or by ipv6_rthdr_rcv() for incoming
 238          * packets.  So we can assume that it is even and that segments is
 239          * greater than or equal to segments_left.
 240          *
 241          * For the same reason we can assume that this option is of type 0.
 242          */
 243         segments = rthdr->hdrlen >> 1;
 244
 245         addrs = ((struct rt0_hdr *)rthdr)->addr;
 246         final_addr = addrs[segments - 1];
 247
 248         addrs += segments - segments_left;
 249         memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs));
 250
 251         addrs[0] = iph->daddr;
 252         iph->daddr = final_addr;
 253 }
 254
 255 static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len, int dir)
 256 {
 257         union {
 258                 struct ipv6hdr *iph;
 259                 struct ipv6_opt_hdr *opth;
 260                 struct ipv6_rt_hdr *rth;
 261                 char *raw;
 262         } exthdr = { .iph = iph };
 263         char *end = exthdr.raw + len;
 264         int nexthdr = iph->nexthdr;
 265
 266         exthdr.iph++;
 267
 268         while (exthdr.raw < end) {
 269                 switch (nexthdr) {
 270                 case NEXTHDR_DEST:
 271                         if (dir == XFRM_POLICY_OUT)
 272                                 ipv6_rearrange_destopt(iph, exthdr.opth);
 273                 case NEXTHDR_HOP:
 274                         if (!zero_out_mutable_opts(exthdr.opth)) {
 275                                 LIMIT_NETDEBUG(
 276                                         KERN_WARNING "overrun %sopts\n",
 277                                         nexthdr == NEXTHDR_HOP ?
 278                                                 "hop" : "dest");
 279                                 return -EINVAL;
 280                         }
 281                         break;
 282
 283                 case NEXTHDR_ROUTING:
 284                         ipv6_rearrange_rthdr(iph, exthdr.rth);
 285                         break;
 286
 287                 default :
 288                         return 0;
 289                 }
 290
 291                 nexthdr = exthdr.opth->nexthdr;
 292                 exthdr.raw += ipv6_optlen(exthdr.opth);
 293         }
 294
 295         return 0;
 296 }
 297
 298 static void ah6_output_done(struct crypto_async_request *base, int err)
 299 {
 300         int extlen;
 301         u8 *iph_base;
 302         u8 *icv;
 303         struct sk_buff *skb = base->data;
 304         struct xfrm_state *x = skb_dst(skb)->xfrm;
 305         struct ah_data *ahp = x->data;
 306         struct ipv6hdr *top_iph = ipv6_hdr(skb);
 307         struct ip_auth_hdr *ah = ip_auth_hdr(skb);
 308         struct tmp_ext *iph_ext;
 309
 310         extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
 311         if (extlen)
 312                 extlen += sizeof(*iph_ext);
 313
 314         iph_base = AH_SKB_CB(skb)->tmp;
 315         iph_ext = ah_tmp_ext(iph_base);
 316         icv = ah_tmp_icv(ahp->ahash, iph_ext, extlen);
 317
 318         memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
 319         memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
 320
 321         if (extlen) {
 322 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 323                 memcpy(&top_iph->saddr, iph_ext, extlen);
 324 #else
 325                 memcpy(&top_iph->daddr, iph_ext, extlen);
 326 #endif
 327         }
 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 IS_ENABLED(CONFIG_IPV6_MIP6)
 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 IS_ENABLED(CONFIG_IPV6_MIP6)
 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         err = ah->nexthdr;
 470
 471         skb->network_header += ah_hlen;
 472         memcpy(skb_network_header(skb), work_iph, hdr_len);
 473         __skb_pull(skb, ah_hlen + hdr_len);
 474         if (x->props.mode == XFRM_MODE_TUNNEL)
 475                 skb_reset_transport_header(skb);
 476         else
 477                 skb_set_transport_header(skb, -hdr_len);
 478 out:
 479         kfree(AH_SKB_CB(skb)->tmp);
 480         xfrm_input_resume(skb, err);
 481 }
 482
 483
 484
 485 static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
 486 {
 487         /*
 488          * Before process AH
 489          * [IPv6][Ext1][Ext2][AH][Dest][Payload]
 490          * |<-------------->| hdr_len
 491          *
 492          * To erase AH:
 493          * Keeping copy of cleared headers. After AH processing,
 494          * Moving the pointer of skb->network_header by using skb_pull as long
 495          * as AH header length. Then copy back the copy as long as hdr_len
 496          * If destination header following AH exists, copy it into after [Ext2].
 497          *
 498          * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
 499          * There is offset of AH before IPv6 header after the process.
 500          */
 501
 502         u8 *auth_data;
 503         u8 *icv;
 504         u8 *work_iph;
 505         struct sk_buff *trailer;
 506         struct crypto_ahash *ahash;
 507         struct ahash_request *req;
 508         struct scatterlist *sg;
 509         struct ip_auth_hdr *ah;
 510         struct ipv6hdr *ip6h;
 511         struct ah_data *ahp;
 512         u16 hdr_len;
 513         u16 ah_hlen;
 514         int nexthdr;
 515         int nfrags;
 516         int err = -ENOMEM;
 517
 518         if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
 519                 goto out;
 520
 521         /* We are going to _remove_ AH header to keep sockets happy,
 522          * so... Later this can change. */
 523         if (skb_unclone(skb, GFP_ATOMIC))
 524                 goto out;
 525
 526         skb->ip_summed = CHECKSUM_NONE;
 527
 528         hdr_len = skb_network_header_len(skb);
 529         ah = (struct ip_auth_hdr *)skb->data;
 530         ahp = x->data;
 531         ahash = ahp->ahash;
 532
 533         nexthdr = ah->nexthdr;
 534         ah_hlen = (ah->hdrlen + 2) << 2;
 535
 536         if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
 537             ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
 538                 goto out;
 539
 540         if (!pskb_may_pull(skb, ah_hlen))
 541                 goto out;
 542
 543
 544         if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
 545                 goto out;
 546         nfrags = err;
 547
 548         ah = (struct ip_auth_hdr *)skb->data;
 549         ip6h = ipv6_hdr(skb);
 550
 551         skb_push(skb, hdr_len);
 552
 553         work_iph = ah_alloc_tmp(ahash, nfrags, hdr_len + ahp->icv_trunc_len);
 554         if (!work_iph)
 555                 goto out;
 556
 557         auth_data = ah_tmp_auth(work_iph, hdr_len);
 558         icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len);
 559         req = ah_tmp_req(ahash, icv);
 560         sg = ah_req_sg(ahash, req);
 561
 562         memcpy(work_iph, ip6h, hdr_len);
 563         memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
 564         memset(ah->auth_data, 0, ahp->icv_trunc_len);
 565
 566         if (ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN))
 567                 goto out_free;
 568
 569         ip6h->priority    = 0;
 570         ip6h->flow_lbl[0] = 0;
 571         ip6h->flow_lbl[1] = 0;
 572         ip6h->flow_lbl[2] = 0;
 573         ip6h->hop_limit   = 0;
 574
 575         sg_init_table(sg, nfrags);
 576         skb_to_sgvec(skb, sg, 0, skb->len);
 577
 578         ahash_request_set_crypt(req, sg, icv, skb->len);
 579         ahash_request_set_callback(req, 0, ah6_input_done, skb);
 580
 581         AH_SKB_CB(skb)->tmp = work_iph;
 582
 583         err = crypto_ahash_digest(req);
 584         if (err) {
 585                 if (err == -EINPROGRESS)
 586                         goto out;
 587
 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_pull(skb, ah_hlen + hdr_len);
 598
 599         if (x->props.mode == XFRM_MODE_TUNNEL)
 600                 skb_reset_transport_header(skb);
 601         else
 602                 skb_set_transport_header(skb, -hdr_len);
 603
 604         err = nexthdr;
 605
 606 out_free:
 607         kfree(work_iph);
 608 out:
 609         return err;
 610 }
 611
 612 static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 613                     u8 type, u8 code, int offset, __be32 info)
 614 {
 615         struct net *net = dev_net(skb->dev);
 616         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 617         struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+offset);
 618         struct xfrm_state *x;
 619
 620         if (type != ICMPV6_PKT_TOOBIG &&
 621             type != NDISC_REDIRECT)
 622                 return;
 623
 624         x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
 625         if (!x)
 626                 return;
 627
 628         if (type == NDISC_REDIRECT)
 629                 ip6_redirect(skb, net, skb->dev->ifindex, 0);
 630         else
 631                 ip6_update_pmtu(skb, net, info, 0, 0);
 632         xfrm_state_put(x);
 633 }
 634
 635 static int ah6_init_state(struct xfrm_state *x)
 636 {
 637         struct ah_data *ahp = NULL;
 638         struct xfrm_algo_desc *aalg_desc;
 639         struct crypto_ahash *ahash;
 640
 641         if (!x->aalg)
 642                 goto error;
 643
 644         if (x->encap)
 645                 goto error;
 646
 647         ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
 648         if (ahp == NULL)
 649                 return -ENOMEM;
 650
 651         ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
 652         if (IS_ERR(ahash))
 653                 goto error;
 654
 655         ahp->ahash = ahash;
 656         if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
 657                                (x->aalg->alg_key_len + 7) / 8))
 658                 goto error;
 659
 660         /*
 661          * Lookup the algorithm description maintained by xfrm_algo,
 662          * verify crypto transform properties, and store information
 663          * we need for AH processing.  This lookup cannot fail here
 664          * after a successful crypto_alloc_hash().
 665          */
 666         aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
 667         BUG_ON(!aalg_desc);
 668
 669         if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
 670             crypto_ahash_digestsize(ahash)) {
 671                 pr_info("AH: %s digestsize %u != %hu\n",
 672                         x->aalg->alg_name, crypto_ahash_digestsize(ahash),
 673                         aalg_desc->uinfo.auth.icv_fullbits/8);
 674                 goto error;
 675         }
 676
 677         ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
 678         ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
 679
 680         BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
 681
 682         x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
 683                                           ahp->icv_trunc_len);
 684         switch (x->props.mode) {
 685         case XFRM_MODE_BEET:
 686         case XFRM_MODE_TRANSPORT:
 687                 break;
 688         case XFRM_MODE_TUNNEL:
 689                 x->props.header_len += sizeof(struct ipv6hdr);
 690                 break;
 691         default:
 692                 goto error;
 693         }
 694         x->data = ahp;
 695
 696         return 0;
 697
 698 error:
 699         if (ahp) {
 700                 crypto_free_ahash(ahp->ahash);
 701                 kfree(ahp);
 702         }
 703         return -EINVAL;
 704 }
 705
 706 static void ah6_destroy(struct xfrm_state *x)
 707 {
 708         struct ah_data *ahp = x->data;
 709
 710         if (!ahp)
 711                 return;
 712
 713         crypto_free_ahash(ahp->ahash);
 714         kfree(ahp);
 715 }
 716
 717 static const struct xfrm_type ah6_type =
 718 {
 719         .description    = "AH6",
 720         .owner          = THIS_MODULE,
 721         .proto          = IPPROTO_AH,
 722         .flags          = XFRM_TYPE_REPLAY_PROT,
 723         .init_state     = ah6_init_state,
 724         .destructor     = ah6_destroy,
 725         .input          = ah6_input,
 726         .output         = ah6_output,
 727         .hdr_offset     = xfrm6_find_1stfragopt,
 728 };
 729
 730 static const struct inet6_protocol ah6_protocol = {
 731         .handler        =       xfrm6_rcv,
 732         .err_handler    =       ah6_err,
 733         .flags          =       INET6_PROTO_NOPOLICY,
 734 };
 735
 736 static int __init ah6_init(void)
 737 {
 738         if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
 739                 pr_info("%s: can't add xfrm type\n", __func__);
 740                 return -EAGAIN;
 741         }
 742
 743         if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) {
 744                 pr_info("%s: can't add protocol\n", __func__);
 745                 xfrm_unregister_type(&ah6_type, AF_INET6);
 746                 return -EAGAIN;
 747         }
 748
 749         return 0;
 750 }
 751
 752 static void __exit ah6_fini(void)
 753 {
 754         if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0)
 755                 pr_info("%s: can't remove protocol\n", __func__);
 756
 757         if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
 758                 pr_info("%s: can't remove xfrm type\n", __func__);
 759
 760 }
 761
 762 module_init(ah6_init);
 763 module_exit(ah6_fini);
 764
 765 MODULE_LICENSE("GPL");
 766 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_AH);