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                                 net_dbg_ratelimited("overrun %sopts\n",
 276                                                     nexthdr == NEXTHDR_HOP ?
 277                                                     "hop" : "dest");
 278                                 return -EINVAL;
 279                         }
 280                         break;
 281
 282                 case NEXTHDR_ROUTING:
 283                         ipv6_rearrange_rthdr(iph, exthdr.rth);
 284                         break;
 285
 286                 default:
 287                         return 0;
 288                 }
 289
 290                 nexthdr = exthdr.opth->nexthdr;
 291                 exthdr.raw += ipv6_optlen(exthdr.opth);
 292         }
 293
 294         return 0;
 295 }
 296
 297 static void ah6_output_done(struct crypto_async_request *base, int err)
 298 {
 299         int extlen;
 300         u8 *iph_base;
 301         u8 *icv;
 302         struct sk_buff *skb = base->data;
 303         struct xfrm_state *x = skb_dst(skb)->xfrm;
 304         struct ah_data *ahp = x->data;
 305         struct ipv6hdr *top_iph = ipv6_hdr(skb);
 306         struct ip_auth_hdr *ah = ip_auth_hdr(skb);
 307         struct tmp_ext *iph_ext;
 308
 309         extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
 310         if (extlen)
 311                 extlen += sizeof(*iph_ext);
 312
 313         iph_base = AH_SKB_CB(skb)->tmp;
 314         iph_ext = ah_tmp_ext(iph_base);
 315         icv = ah_tmp_icv(ahp->ahash, iph_ext, extlen);
 316
 317         memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
 318         memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
 319
 320         if (extlen) {
 321 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 322                 memcpy(&top_iph->saddr, iph_ext, extlen);
 323 #else
 324                 memcpy(&top_iph->daddr, iph_ext, extlen);
 325 #endif
 326         }
 327
 328         kfree(AH_SKB_CB(skb)->tmp);
 329         xfrm_output_resume(skb, err);
 330 }
 331
 332 static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
 333 {
 334         int err;
 335         int nfrags;
 336         int extlen;
 337         u8 *iph_base;
 338         u8 *icv;
 339         u8 nexthdr;
 340         struct sk_buff *trailer;
 341         struct crypto_ahash *ahash;
 342         struct ahash_request *req;
 343         struct scatterlist *sg;
 344         struct ipv6hdr *top_iph;
 345         struct ip_auth_hdr *ah;
 346         struct ah_data *ahp;
 347         struct tmp_ext *iph_ext;
 348         int seqhi_len = 0;
 349         __be32 *seqhi;
 350         int sglists = 0;
 351         struct scatterlist *seqhisg;
 352
 353         ahp = x->data;
 354         ahash = ahp->ahash;
 355
 356         err = skb_cow_data(skb, 0, &trailer);
 357         if (err < 0)
 358                 goto out;
 359         nfrags = err;
 360
 361         skb_push(skb, -skb_network_offset(skb));
 362         extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
 363         if (extlen)
 364                 extlen += sizeof(*iph_ext);
 365
 366         if (x->props.flags & XFRM_STATE_ESN) {
 367                 sglists = 1;
 368                 seqhi_len = sizeof(*seqhi);
 369         }
 370         err = -ENOMEM;
 371         iph_base = ah_alloc_tmp(ahash, nfrags + sglists, IPV6HDR_BASELEN +
 372                                 extlen + seqhi_len);
 373         if (!iph_base)
 374                 goto out;
 375
 376         iph_ext = ah_tmp_ext(iph_base);
 377         seqhi = (__be32 *)((char *)iph_ext + extlen);
 378         icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
 379         req = ah_tmp_req(ahash, icv);
 380         sg = ah_req_sg(ahash, req);
 381         seqhisg = sg + nfrags;
 382
 383         ah = ip_auth_hdr(skb);
 384         memset(ah->auth_data, 0, ahp->icv_trunc_len);
 385
 386         top_iph = ipv6_hdr(skb);
 387         top_iph->payload_len = htons(skb->len - sizeof(*top_iph));
 388
 389         nexthdr = *skb_mac_header(skb);
 390         *skb_mac_header(skb) = IPPROTO_AH;
 391
 392         /* When there are no extension headers, we only need to save the first
 393          * 8 bytes of the base IP header.
 394          */
 395         memcpy(iph_base, top_iph, IPV6HDR_BASELEN);
 396
 397         if (extlen) {
 398 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 399                 memcpy(iph_ext, &top_iph->saddr, extlen);
 400 #else
 401                 memcpy(iph_ext, &top_iph->daddr, extlen);
 402 #endif
 403                 err = ipv6_clear_mutable_options(top_iph,
 404                                                  extlen - sizeof(*iph_ext) +
 405                                                  sizeof(*top_iph),
 406                                                  XFRM_POLICY_OUT);
 407                 if (err)
 408                         goto out_free;
 409         }
 410
 411         ah->nexthdr = nexthdr;
 412
 413         top_iph->priority    = 0;
 414         top_iph->flow_lbl[0] = 0;
 415         top_iph->flow_lbl[1] = 0;
 416         top_iph->flow_lbl[2] = 0;
 417         top_iph->hop_limit   = 0;
 418
 419         ah->hdrlen  = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
 420
 421         ah->reserved = 0;
 422         ah->spi = x->id.spi;
 423         ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
 424
 425         sg_init_table(sg, nfrags + sglists);
 426         skb_to_sgvec_nomark(skb, sg, 0, skb->len);
 427
 428         if (x->props.flags & XFRM_STATE_ESN) {
 429                 /* Attach seqhi sg right after packet payload */
 430                 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
 431                 sg_set_buf(seqhisg, seqhi, seqhi_len);
 432         }
 433         ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
 434         ahash_request_set_callback(req, 0, ah6_output_done, skb);
 435
 436         AH_SKB_CB(skb)->tmp = iph_base;
 437
 438         err = crypto_ahash_digest(req);
 439         if (err) {
 440                 if (err == -EINPROGRESS)
 441                         goto out;
 442
 443                 if (err == -EBUSY)
 444                         err = NET_XMIT_DROP;
 445                 goto out_free;
 446         }
 447
 448         memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
 449         memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
 450
 451         if (extlen) {
 452 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 453                 memcpy(&top_iph->saddr, iph_ext, extlen);
 454 #else
 455                 memcpy(&top_iph->daddr, iph_ext, extlen);
 456 #endif
 457         }
 458
 459 out_free:
 460         kfree(iph_base);
 461 out:
 462         return err;
 463 }
 464
 465 static void ah6_input_done(struct crypto_async_request *base, int err)
 466 {
 467         u8 *auth_data;
 468         u8 *icv;
 469         u8 *work_iph;
 470         struct sk_buff *skb = base->data;
 471         struct xfrm_state *x = xfrm_input_state(skb);
 472         struct ah_data *ahp = x->data;
 473         struct ip_auth_hdr *ah = ip_auth_hdr(skb);
 474         int hdr_len = skb_network_header_len(skb);
 475         int ah_hlen = (ah->hdrlen + 2) << 2;
 476
 477         work_iph = AH_SKB_CB(skb)->tmp;
 478         auth_data = ah_tmp_auth(work_iph, hdr_len);
 479         icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);
 480
 481         err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
 482         if (err)
 483                 goto out;
 484
 485         err = ah->nexthdr;
 486
 487         skb->network_header += ah_hlen;
 488         memcpy(skb_network_header(skb), work_iph, hdr_len);
 489         __skb_pull(skb, ah_hlen + hdr_len);
 490         if (x->props.mode == XFRM_MODE_TUNNEL)
 491                 skb_reset_transport_header(skb);
 492         else
 493                 skb_set_transport_header(skb, -hdr_len);
 494 out:
 495         kfree(AH_SKB_CB(skb)->tmp);
 496         xfrm_input_resume(skb, err);
 497 }
 498
 499
 500
 501 static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
 502 {
 503         /*
 504          * Before process AH
 505          * [IPv6][Ext1][Ext2][AH][Dest][Payload]
 506          * |<-------------->| hdr_len
 507          *
 508          * To erase AH:
 509          * Keeping copy of cleared headers. After AH processing,
 510          * Moving the pointer of skb->network_header by using skb_pull as long
 511          * as AH header length. Then copy back the copy as long as hdr_len
 512          * If destination header following AH exists, copy it into after [Ext2].
 513          *
 514          * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
 515          * There is offset of AH before IPv6 header after the process.
 516          */
 517
 518         u8 *auth_data;
 519         u8 *icv;
 520         u8 *work_iph;
 521         struct sk_buff *trailer;
 522         struct crypto_ahash *ahash;
 523         struct ahash_request *req;
 524         struct scatterlist *sg;
 525         struct ip_auth_hdr *ah;
 526         struct ipv6hdr *ip6h;
 527         struct ah_data *ahp;
 528         u16 hdr_len;
 529         u16 ah_hlen;
 530         int nexthdr;
 531         int nfrags;
 532         int err = -ENOMEM;
 533         int seqhi_len = 0;
 534         __be32 *seqhi;
 535         int sglists = 0;
 536         struct scatterlist *seqhisg;
 537
 538         if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
 539                 goto out;
 540
 541         /* We are going to _remove_ AH header to keep sockets happy,
 542          * so... Later this can change. */
 543         if (skb_unclone(skb, GFP_ATOMIC))
 544                 goto out;
 545
 546         skb->ip_summed = CHECKSUM_NONE;
 547
 548         hdr_len = skb_network_header_len(skb);
 549         ah = (struct ip_auth_hdr *)skb->data;
 550         ahp = x->data;
 551         ahash = ahp->ahash;
 552
 553         nexthdr = ah->nexthdr;
 554         ah_hlen = (ah->hdrlen + 2) << 2;
 555
 556         if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
 557             ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
 558                 goto out;
 559
 560         if (!pskb_may_pull(skb, ah_hlen))
 561                 goto out;
 562
 563         err = skb_cow_data(skb, 0, &trailer);
 564         if (err < 0)
 565                 goto out;
 566         nfrags = err;
 567
 568         ah = (struct ip_auth_hdr *)skb->data;
 569         ip6h = ipv6_hdr(skb);
 570
 571         skb_push(skb, hdr_len);
 572
 573         if (x->props.flags & XFRM_STATE_ESN) {
 574                 sglists = 1;
 575                 seqhi_len = sizeof(*seqhi);
 576         }
 577
 578         work_iph = ah_alloc_tmp(ahash, nfrags + sglists, hdr_len +
 579                                 ahp->icv_trunc_len + seqhi_len);
 580         if (!work_iph)
 581                 goto out;
 582
 583         auth_data = ah_tmp_auth((u8 *)work_iph, hdr_len);
 584         seqhi = (__be32 *)(auth_data + ahp->icv_trunc_len);
 585         icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
 586         req = ah_tmp_req(ahash, icv);
 587         sg = ah_req_sg(ahash, req);
 588         seqhisg = sg + nfrags;
 589
 590         memcpy(work_iph, ip6h, hdr_len);
 591         memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
 592         memset(ah->auth_data, 0, ahp->icv_trunc_len);
 593
 594         if (ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN))
 595                 goto out_free;
 596
 597         ip6h->priority    = 0;
 598         ip6h->flow_lbl[0] = 0;
 599         ip6h->flow_lbl[1] = 0;
 600         ip6h->flow_lbl[2] = 0;
 601         ip6h->hop_limit   = 0;
 602
 603         sg_init_table(sg, nfrags + sglists);
 604         skb_to_sgvec_nomark(skb, sg, 0, skb->len);
 605
 606         if (x->props.flags & XFRM_STATE_ESN) {
 607                 /* Attach seqhi sg right after packet payload */
 608                 *seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
 609                 sg_set_buf(seqhisg, seqhi, seqhi_len);
 610         }
 611
 612         ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
 613         ahash_request_set_callback(req, 0, ah6_input_done, skb);
 614
 615         AH_SKB_CB(skb)->tmp = work_iph;
 616
 617         err = crypto_ahash_digest(req);
 618         if (err) {
 619                 if (err == -EINPROGRESS)
 620                         goto out;
 621
 622                 goto out_free;
 623         }
 624
 625         err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
 626         if (err)
 627                 goto out_free;
 628
 629         skb->network_header += ah_hlen;
 630         memcpy(skb_network_header(skb), work_iph, hdr_len);
 631         __skb_pull(skb, ah_hlen + hdr_len);
 632
 633         if (x->props.mode == XFRM_MODE_TUNNEL)
 634                 skb_reset_transport_header(skb);
 635         else
 636                 skb_set_transport_header(skb, -hdr_len);
 637
 638         err = nexthdr;
 639
 640 out_free:
 641         kfree(work_iph);
 642 out:
 643         return err;
 644 }
 645
 646 static int ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 647                    u8 type, u8 code, int offset, __be32 info)
 648 {
 649         struct net *net = dev_net(skb->dev);
 650         struct ipv6hdr *iph = (struct ipv6hdr *)skb->data;
 651         struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+offset);
 652         struct xfrm_state *x;
 653
 654         if (type != ICMPV6_PKT_TOOBIG &&
 655             type != NDISC_REDIRECT)
 656                 return 0;
 657
 658         x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
 659         if (!x)
 660                 return 0;
 661
 662         if (type == NDISC_REDIRECT)
 663                 ip6_redirect(skb, net, skb->dev->ifindex, 0);
 664         else
 665                 ip6_update_pmtu(skb, net, info, 0, 0);
 666         xfrm_state_put(x);
 667
 668         return 0;
 669 }
 670
 671 static int ah6_init_state(struct xfrm_state *x)
 672 {
 673         struct ah_data *ahp = NULL;
 674         struct xfrm_algo_desc *aalg_desc;
 675         struct crypto_ahash *ahash;
 676
 677         if (!x->aalg)
 678                 goto error;
 679
 680         if (x->encap)
 681                 goto error;
 682
 683         ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
 684         if (!ahp)
 685                 return -ENOMEM;
 686
 687         ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
 688         if (IS_ERR(ahash))
 689                 goto error;
 690
 691         ahp->ahash = ahash;
 692         if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
 693                                (x->aalg->alg_key_len + 7) / 8))
 694                 goto error;
 695
 696         /*
 697          * Lookup the algorithm description maintained by xfrm_algo,
 698          * verify crypto transform properties, and store information
 699          * we need for AH processing.  This lookup cannot fail here
 700          * after a successful crypto_alloc_hash().
 701          */
 702         aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
 703         BUG_ON(!aalg_desc);
 704
 705         if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
 706             crypto_ahash_digestsize(ahash)) {
 707                 pr_info("AH: %s digestsize %u != %hu\n",
 708                         x->aalg->alg_name, crypto_ahash_digestsize(ahash),
 709                         aalg_desc->uinfo.auth.icv_fullbits/8);
 710                 goto error;
 711         }
 712
 713         ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
 714         ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
 715
 716         x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
 717                                           ahp->icv_trunc_len);
 718         switch (x->props.mode) {
 719         case XFRM_MODE_BEET:
 720         case XFRM_MODE_TRANSPORT:
 721                 break;
 722         case XFRM_MODE_TUNNEL:
 723                 x->props.header_len += sizeof(struct ipv6hdr);
 724                 break;
 725         default:
 726                 goto error;
 727         }
 728         x->data = ahp;
 729
 730         return 0;
 731
 732 error:
 733         if (ahp) {
 734                 crypto_free_ahash(ahp->ahash);
 735                 kfree(ahp);
 736         }
 737         return -EINVAL;
 738 }
 739
 740 static void ah6_destroy(struct xfrm_state *x)
 741 {
 742         struct ah_data *ahp = x->data;
 743
 744         if (!ahp)
 745                 return;
 746
 747         crypto_free_ahash(ahp->ahash);
 748         kfree(ahp);
 749 }
 750
 751 static int ah6_rcv_cb(struct sk_buff *skb, int err)
 752 {
 753         return 0;
 754 }
 755
 756 static const struct xfrm_type ah6_type = {
 757         .description    = "AH6",
 758         .owner          = THIS_MODULE,
 759         .proto          = IPPROTO_AH,
 760         .flags          = XFRM_TYPE_REPLAY_PROT,
 761         .init_state     = ah6_init_state,
 762         .destructor     = ah6_destroy,
 763         .input          = ah6_input,
 764         .output         = ah6_output,
 765         .hdr_offset     = xfrm6_find_1stfragopt,
 766 };
 767
 768 static struct xfrm6_protocol ah6_protocol = {
 769         .handler        =       xfrm6_rcv,
 770         .cb_handler     =       ah6_rcv_cb,
 771         .err_handler    =       ah6_err,
 772         .priority       =       0,
 773 };
 774
 775 static int __init ah6_init(void)
 776 {
 777         if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
 778                 pr_info("%s: can't add xfrm type\n", __func__);
 779                 return -EAGAIN;
 780         }
 781
 782         if (xfrm6_protocol_register(&ah6_protocol, IPPROTO_AH) < 0) {
 783                 pr_info("%s: can't add protocol\n", __func__);
 784                 xfrm_unregister_type(&ah6_type, AF_INET6);
 785                 return -EAGAIN;
 786         }
 787
 788         return 0;
 789 }
 790
 791 static void __exit ah6_fini(void)
 792 {
 793         if (xfrm6_protocol_deregister(&ah6_protocol, IPPROTO_AH) < 0)
 794                 pr_info("%s: can't remove protocol\n", __func__);
 795
 796         if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
 797                 pr_info("%s: can't remove xfrm type\n", __func__);
 798
 799 }
 800
 801 module_init(ah6_init);
 802 module_exit(ah6_fini);
 803
 804 MODULE_LICENSE("GPL");
 805 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_AH);