root/net/ipv6/ah6.c

DEFINITIONS

1. ah_alloc_tmp
2. ah_tmp_ext
3. ah_tmp_auth
4. ah_tmp_icv
5. ah_tmp_req
6. ah_req_sg
7. zero_out_mutable_opts
8. ipv6_rearrange_destopt
9. ipv6_rearrange_destopt
10. ipv6_rearrange_rthdr
11. ipv6_clear_mutable_options
12. ah6_output_done
13. ah6_output
14. ah6_input_done
15. ah6_input
16. ah6_err
17. ah6_init_state
18. ah6_destroy
19. ah6_rcv_cb
20. ah6_init
21. ah6_fini

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C)2002 USAGI/WIDE Project
   4  *
   5  * Authors
   6  *
   7  *      Mitsuru KANDA @USAGI       : IPv6 Support
   8  *      Kazunori MIYAZAWA @USAGI   :
   9  *      Kunihiro Ishiguro <kunihiro@ipinfusion.com>
  10  *
  11  *      This file is derived from net/ipv4/ah.c.
  12  */
  13 
  14 #define pr_fmt(fmt) "IPv6: " fmt
  15 
  16 #include <crypto/algapi.h>
  17 #include <crypto/hash.h>
  18 #include <linux/module.h>
  19 #include <linux/slab.h>
  20 #include <net/ip.h>
  21 #include <net/ah.h>
  22 #include <linux/crypto.h>
  23 #include <linux/pfkeyv2.h>
  24 #include <linux/string.h>
  25 #include <linux/scatterlist.h>
  26 #include <net/ip6_route.h>
  27 #include <net/icmp.h>
  28 #include <net/ipv6.h>
  29 #include <net/protocol.h>
  30 #include <net/xfrm.h>
  31 
  32 #define IPV6HDR_BASELEN 8
  33 
  34 struct tmp_ext {
  35 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  36                 struct in6_addr saddr;
  37 #endif
  38                 struct in6_addr daddr;
  39                 char hdrs[0];
  40 };
  41 
  42 struct ah_skb_cb {
  43         struct xfrm_skb_cb xfrm;
  44         void *tmp;
  45 };
  46 
  47 #define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0]))
  48 
  49 static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags,
  50                           unsigned int size)
  51 {
  52         unsigned int len;
  53 
  54         len = size + crypto_ahash_digestsize(ahash) +
  55               (crypto_ahash_alignmask(ahash) &
  56                ~(crypto_tfm_ctx_alignment() - 1));
  57 
  58         len = ALIGN(len, crypto_tfm_ctx_alignment());
  59 
  60         len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash);
  61         len = ALIGN(len, __alignof__(struct scatterlist));
  62 
  63         len += sizeof(struct scatterlist) * nfrags;
  64 
  65         return kmalloc(len, GFP_ATOMIC);
  66 }
  67 
  68 static inline struct tmp_ext *ah_tmp_ext(void *base)
  69 {
  70         return base + IPV6HDR_BASELEN;
  71 }
  72 
  73 static inline u8 *ah_tmp_auth(u8 *tmp, unsigned int offset)
  74 {
  75         return tmp + offset;
  76 }
  77 
  78 static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp,
  79                              unsigned int offset)
  80 {
  81         return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1);
  82 }
  83 
  84 static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash,
  85                                                u8 *icv)
  86 {
  87         struct ahash_request *req;
  88 
  89         req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash),
  90                                 crypto_tfm_ctx_alignment());
  91 
  92         ahash_request_set_tfm(req, ahash);
  93 
  94         return req;
  95 }
  96 
  97 static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash,
  98                                              struct ahash_request *req)
  99 {
 100         return (void *)ALIGN((unsigned long)(req + 1) +
 101                              crypto_ahash_reqsize(ahash),
 102                              __alignof__(struct scatterlist));
 103 }
 104 
 105 static bool zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr)
 106 {
 107         u8 *opt = (u8 *)opthdr;
 108         int len = ipv6_optlen(opthdr);
 109         int off = 0;
 110         int optlen = 0;
 111 
 112         off += 2;
 113         len -= 2;
 114 
 115         while (len > 0) {
 116 
 117                 switch (opt[off]) {
 118 
 119                 case IPV6_TLV_PAD1:
 120                         optlen = 1;
 121                         break;
 122                 default:
 123                         if (len < 2)
 124                                 goto bad;
 125                         optlen = opt[off+1]+2;
 126                         if (len < optlen)
 127                                 goto bad;
 128                         if (opt[off] & 0x20)
 129                                 memset(&opt[off+2], 0, opt[off+1]);
 130                         break;
 131                 }
 132 
 133                 off += optlen;
 134                 len -= optlen;
 135         }
 136         if (len == 0)
 137                 return true;
 138 
 139 bad:
 140         return false;
 141 }
 142 
 143 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 144 /**
 145  *      ipv6_rearrange_destopt - rearrange IPv6 destination options header
 146  *      @iph: IPv6 header
 147  *      @destopt: destionation options header
 148  */
 149 static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt)
 150 {
 151         u8 *opt = (u8 *)destopt;
 152         int len = ipv6_optlen(destopt);
 153         int off = 0;
 154         int optlen = 0;
 155 
 156         off += 2;
 157         len -= 2;
 158 
 159         while (len > 0) {
 160 
 161                 switch (opt[off]) {
 162 
 163                 case IPV6_TLV_PAD1:
 164                         optlen = 1;
 165                         break;
 166                 default:
 167                         if (len < 2)
 168                                 goto bad;
 169                         optlen = opt[off+1]+2;
 170                         if (len < optlen)
 171                                 goto bad;
 172 
 173                         /* Rearrange the source address in @iph and the
 174                          * addresses in home address option for final source.
 175                          * See 11.3.2 of RFC 3775 for details.
 176                          */
 177                         if (opt[off] == IPV6_TLV_HAO) {
 178                                 struct in6_addr final_addr;
 179                                 struct ipv6_destopt_hao *hao;
 180 
 181                                 hao = (struct ipv6_destopt_hao *)&opt[off];
 182                                 if (hao->length != sizeof(hao->addr)) {
 183                                         net_warn_ratelimited("destopt hao: invalid header length: %u\n",
 184                                                              hao->length);
 185                                         goto bad;
 186                                 }
 187                                 final_addr = hao->addr;
 188                                 hao->addr = iph->saddr;
 189                                 iph->saddr = final_addr;
 190                         }
 191                         break;
 192                 }
 193 
 194                 off += optlen;
 195                 len -= optlen;
 196         }
 197         /* Note: ok if len == 0 */
 198 bad:
 199         return;
 200 }
 201 #else
 202 static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt) {}
 203 #endif
 204 
 205 /**
 206  *      ipv6_rearrange_rthdr - rearrange IPv6 routing header
 207  *      @iph: IPv6 header
 208  *      @rthdr: routing header
 209  *
 210  *      Rearrange the destination address in @iph and the addresses in @rthdr
 211  *      so that they appear in the order they will at the final destination.
 212  *      See Appendix A2 of RFC 2402 for details.
 213  */
 214 static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr)
 215 {
 216         int segments, segments_left;
 217         struct in6_addr *addrs;
 218         struct in6_addr final_addr;
 219 
 220         segments_left = rthdr->segments_left;
 221         if (segments_left == 0)
 222                 return;
 223         rthdr->segments_left = 0;
 224 
 225         /* The value of rthdr->hdrlen has been verified either by the system
 226          * call if it is locally generated, or by ipv6_rthdr_rcv() for incoming
 227          * packets.  So we can assume that it is even and that segments is
 228          * greater than or equal to segments_left.
 229          *
 230          * For the same reason we can assume that this option is of type 0.
 231          */
 232         segments = rthdr->hdrlen >> 1;
 233 
 234         addrs = ((struct rt0_hdr *)rthdr)->addr;
 235         final_addr = addrs[segments - 1];
 236 
 237         addrs += segments - segments_left;
 238         memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs));
 239 
 240         addrs[0] = iph->daddr;
 241         iph->daddr = final_addr;
 242 }
 243 
 244 static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len, int dir)
 245 {
 246         union {
 247                 struct ipv6hdr *iph;
 248                 struct ipv6_opt_hdr *opth;
 249                 struct ipv6_rt_hdr *rth;
 250                 char *raw;
 251         } exthdr = { .iph = iph };
 252         char *end = exthdr.raw + len;
 253         int nexthdr = iph->nexthdr;
 254 
 255         exthdr.iph++;
 256 
 257         while (exthdr.raw < end) {
 258                 switch (nexthdr) {
 259                 case NEXTHDR_DEST:
 260                         if (dir == XFRM_POLICY_OUT)
 261                                 ipv6_rearrange_destopt(iph, exthdr.opth);
 262                         /* fall through */
 263                 case NEXTHDR_HOP:
 264                         if (!zero_out_mutable_opts(exthdr.opth)) {
 265                                 net_dbg_ratelimited("overrun %sopts\n",
 266                                                     nexthdr == NEXTHDR_HOP ?
 267                                                     "hop" : "dest");
 268                                 return -EINVAL;
 269                         }
 270                         break;
 271 
 272                 case NEXTHDR_ROUTING:
 273                         ipv6_rearrange_rthdr(iph, exthdr.rth);
 274                         break;
 275 
 276                 default:
 277                         return 0;
 278                 }
 279 
 280                 nexthdr = exthdr.opth->nexthdr;
 281                 exthdr.raw += ipv6_optlen(exthdr.opth);
 282         }
 283 
 284         return 0;
 285 }
 286 
 287 static void ah6_output_done(struct crypto_async_request *base, int err)
 288 {
 289         int extlen;
 290         u8 *iph_base;
 291         u8 *icv;
 292         struct sk_buff *skb = base->data;
 293         struct xfrm_state *x = skb_dst(skb)->xfrm;
 294         struct ah_data *ahp = x->data;
 295         struct ipv6hdr *top_iph = ipv6_hdr(skb);
 296         struct ip_auth_hdr *ah = ip_auth_hdr(skb);
 297         struct tmp_ext *iph_ext;
 298 
 299         extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
 300         if (extlen)
 301                 extlen += sizeof(*iph_ext);
 302 
 303         iph_base = AH_SKB_CB(skb)->tmp;
 304         iph_ext = ah_tmp_ext(iph_base);
 305         icv = ah_tmp_icv(ahp->ahash, iph_ext, extlen);
 306 
 307         memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
 308         memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
 309 
 310         if (extlen) {
 311 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 312                 memcpy(&top_iph->saddr, iph_ext, extlen);
 313 #else
 314                 memcpy(&top_iph->daddr, iph_ext, extlen);
 315 #endif
 316         }
 317 
 318         kfree(AH_SKB_CB(skb)->tmp);
 319         xfrm_output_resume(skb, err);
 320 }
 321 
 322 static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
 323 {
 324         int err;
 325         int nfrags;
 326         int extlen;
 327         u8 *iph_base;
 328         u8 *icv;
 329         u8 nexthdr;
 330         struct sk_buff *trailer;
 331         struct crypto_ahash *ahash;
 332         struct ahash_request *req;
 333         struct scatterlist *sg;
 334         struct ipv6hdr *top_iph;
 335         struct ip_auth_hdr *ah;
 336         struct ah_data *ahp;
 337         struct tmp_ext *iph_ext;
 338         int seqhi_len = 0;
 339         __be32 *seqhi;
 340         int sglists = 0;
 341         struct scatterlist *seqhisg;
 342 
 343         ahp = x->data;
 344         ahash = ahp->ahash;
 345 
 346         err = skb_cow_data(skb, 0, &trailer);
 347         if (err < 0)
 348                 goto out;
 349         nfrags = err;
 350 
 351         skb_push(skb, -skb_network_offset(skb));
 352         extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
 353         if (extlen)
 354                 extlen += sizeof(*iph_ext);
 355 
 356         if (x->props.flags & XFRM_STATE_ESN) {
 357                 sglists = 1;
 358                 seqhi_len = sizeof(*seqhi);
 359         }
 360         err = -ENOMEM;
 361         iph_base = ah_alloc_tmp(ahash, nfrags + sglists, IPV6HDR_BASELEN +
 362                                 extlen + seqhi_len);
 363         if (!iph_base)
 364                 goto out;
 365 
 366         iph_ext = ah_tmp_ext(iph_base);
 367         seqhi = (__be32 *)((char *)iph_ext + extlen);
 368         icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
 369         req = ah_tmp_req(ahash, icv);
 370         sg = ah_req_sg(ahash, req);
 371         seqhisg = sg + nfrags;
 372 
 373         ah = ip_auth_hdr(skb);
 374         memset(ah->auth_data, 0, ahp->icv_trunc_len);
 375 
 376         top_iph = ipv6_hdr(skb);
 377         top_iph->payload_len = htons(skb->len - sizeof(*top_iph));
 378 
 379         nexthdr = *skb_mac_header(skb);
 380         *skb_mac_header(skb) = IPPROTO_AH;
 381 
 382         /* When there are no extension headers, we only need to save the first
 383          * 8 bytes of the base IP header.
 384          */
 385         memcpy(iph_base, top_iph, IPV6HDR_BASELEN);
 386 
 387         if (extlen) {
 388 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 389                 memcpy(iph_ext, &top_iph->saddr, extlen);
 390 #else
 391                 memcpy(iph_ext, &top_iph->daddr, extlen);
 392 #endif
 393                 err = ipv6_clear_mutable_options(top_iph,
 394                                                  extlen - sizeof(*iph_ext) +
 395                                                  sizeof(*top_iph),
 396                                                  XFRM_POLICY_OUT);
 397                 if (err)
 398                         goto out_free;
 399         }
 400 
 401         ah->nexthdr = nexthdr;
 402 
 403         top_iph->priority    = 0;
 404         top_iph->flow_lbl[0] = 0;
 405         top_iph->flow_lbl[1] = 0;
 406         top_iph->flow_lbl[2] = 0;
 407         top_iph->hop_limit   = 0;
 408 
 409         ah->hdrlen  = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
 410 
 411         ah->reserved = 0;
 412         ah->spi = x->id.spi;
 413         ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
 414 
 415         sg_init_table(sg, nfrags + sglists);
 416         err = skb_to_sgvec_nomark(skb, sg, 0, skb->len);
 417         if (unlikely(err < 0))
 418                 goto out_free;
 419 
 420         if (x->props.flags & XFRM_STATE_ESN) {
 421                 /* Attach seqhi sg right after packet payload */
 422                 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
 423                 sg_set_buf(seqhisg, seqhi, seqhi_len);
 424         }
 425         ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
 426         ahash_request_set_callback(req, 0, ah6_output_done, skb);
 427 
 428         AH_SKB_CB(skb)->tmp = iph_base;
 429 
 430         err = crypto_ahash_digest(req);
 431         if (err) {
 432                 if (err == -EINPROGRESS)
 433                         goto out;
 434 
 435                 if (err == -ENOSPC)
 436                         err = NET_XMIT_DROP;
 437                 goto out_free;
 438         }
 439 
 440         memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
 441         memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
 442 
 443         if (extlen) {
 444 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 445                 memcpy(&top_iph->saddr, iph_ext, extlen);
 446 #else
 447                 memcpy(&top_iph->daddr, iph_ext, extlen);
 448 #endif
 449         }
 450 
 451 out_free:
 452         kfree(iph_base);
 453 out:
 454         return err;
 455 }
 456 
 457 static void ah6_input_done(struct crypto_async_request *base, int err)
 458 {
 459         u8 *auth_data;
 460         u8 *icv;
 461         u8 *work_iph;
 462         struct sk_buff *skb = base->data;
 463         struct xfrm_state *x = xfrm_input_state(skb);
 464         struct ah_data *ahp = x->data;
 465         struct ip_auth_hdr *ah = ip_auth_hdr(skb);
 466         int hdr_len = skb_network_header_len(skb);
 467         int ah_hlen = ipv6_authlen(ah);
 468 
 469         if (err)
 470                 goto out;
 471 
 472         work_iph = AH_SKB_CB(skb)->tmp;
 473         auth_data = ah_tmp_auth(work_iph, hdr_len);
 474         icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);
 475 
 476         err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
 477         if (err)
 478                 goto out;
 479 
 480         err = ah->nexthdr;
 481 
 482         skb->network_header += ah_hlen;
 483         memcpy(skb_network_header(skb), work_iph, hdr_len);
 484         __skb_pull(skb, ah_hlen + hdr_len);
 485         if (x->props.mode == XFRM_MODE_TUNNEL)
 486                 skb_reset_transport_header(skb);
 487         else
 488                 skb_set_transport_header(skb, -hdr_len);
 489 out:
 490         kfree(AH_SKB_CB(skb)->tmp);
 491         xfrm_input_resume(skb, err);
 492 }
 493 
 494 
 495 
 496 static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
 497 {
 498         /*
 499          * Before process AH
 500          * [IPv6][Ext1][Ext2][AH][Dest][Payload]
 501          * |<-------------->| hdr_len
 502          *
 503          * To erase AH:
 504          * Keeping copy of cleared headers. After AH processing,
 505          * Moving the pointer of skb->network_header by using skb_pull as long
 506          * as AH header length. Then copy back the copy as long as hdr_len
 507          * If destination header following AH exists, copy it into after [Ext2].
 508          *
 509          * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
 510          * There is offset of AH before IPv6 header after the process.
 511          */
 512 
 513         u8 *auth_data;
 514         u8 *icv;
 515         u8 *work_iph;
 516         struct sk_buff *trailer;
 517         struct crypto_ahash *ahash;
 518         struct ahash_request *req;
 519         struct scatterlist *sg;
 520         struct ip_auth_hdr *ah;
 521         struct ipv6hdr *ip6h;
 522         struct ah_data *ahp;
 523         u16 hdr_len;
 524         u16 ah_hlen;
 525         int nexthdr;
 526         int nfrags;
 527         int err = -ENOMEM;
 528         int seqhi_len = 0;
 529         __be32 *seqhi;
 530         int sglists = 0;
 531         struct scatterlist *seqhisg;
 532 
 533         if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
 534                 goto out;
 535 
 536         /* We are going to _remove_ AH header to keep sockets happy,
 537          * so... Later this can change. */
 538         if (skb_unclone(skb, GFP_ATOMIC))
 539                 goto out;
 540 
 541         skb->ip_summed = CHECKSUM_NONE;
 542 
 543         hdr_len = skb_network_header_len(skb);
 544         ah = (struct ip_auth_hdr *)skb->data;
 545         ahp = x->data;
 546         ahash = ahp->ahash;
 547 
 548         nexthdr = ah->nexthdr;
 549         ah_hlen = ipv6_authlen(ah);
 550 
 551         if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
 552             ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
 553                 goto out;
 554 
 555         if (!pskb_may_pull(skb, ah_hlen))
 556                 goto out;
 557 
 558         err = skb_cow_data(skb, 0, &trailer);
 559         if (err < 0)
 560                 goto out;
 561         nfrags = err;
 562 
 563         ah = (struct ip_auth_hdr *)skb->data;
 564         ip6h = ipv6_hdr(skb);
 565 
 566         skb_push(skb, hdr_len);
 567 
 568         if (x->props.flags & XFRM_STATE_ESN) {
 569                 sglists = 1;
 570                 seqhi_len = sizeof(*seqhi);
 571         }
 572 
 573         work_iph = ah_alloc_tmp(ahash, nfrags + sglists, hdr_len +
 574                                 ahp->icv_trunc_len + seqhi_len);
 575         if (!work_iph) {
 576                 err = -ENOMEM;
 577                 goto out;
 578         }
 579 
 580         auth_data = ah_tmp_auth((u8 *)work_iph, hdr_len);
 581         seqhi = (__be32 *)(auth_data + ahp->icv_trunc_len);
 582         icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
 583         req = ah_tmp_req(ahash, icv);
 584         sg = ah_req_sg(ahash, req);
 585         seqhisg = sg + nfrags;
 586 
 587         memcpy(work_iph, ip6h, hdr_len);
 588         memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
 589         memset(ah->auth_data, 0, ahp->icv_trunc_len);
 590 
 591         if (ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN))
 592                 goto out_free;
 593 
 594         ip6h->priority    = 0;
 595         ip6h->flow_lbl[0] = 0;
 596         ip6h->flow_lbl[1] = 0;
 597         ip6h->flow_lbl[2] = 0;
 598         ip6h->hop_limit   = 0;
 599 
 600         sg_init_table(sg, nfrags + sglists);
 601         err = skb_to_sgvec_nomark(skb, sg, 0, skb->len);
 602         if (unlikely(err < 0))
 603                 goto out_free;
 604 
 605         if (x->props.flags & XFRM_STATE_ESN) {
 606                 /* Attach seqhi sg right after packet payload */
 607                 *seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
 608                 sg_set_buf(seqhisg, seqhi, seqhi_len);
 609         }
 610 
 611         ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
 612         ahash_request_set_callback(req, 0, ah6_input_done, skb);
 613 
 614         AH_SKB_CB(skb)->tmp = work_iph;
 615 
 616         err = crypto_ahash_digest(req);
 617         if (err) {
 618                 if (err == -EINPROGRESS)
 619                         goto out;
 620 
 621                 goto out_free;
 622         }
 623 
 624         err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
 625         if (err)
 626                 goto out_free;
 627 
 628         skb->network_header += ah_hlen;
 629         memcpy(skb_network_header(skb), work_iph, hdr_len);
 630         __skb_pull(skb, ah_hlen + hdr_len);
 631 
 632         if (x->props.mode == XFRM_MODE_TUNNEL)
 633                 skb_reset_transport_header(skb);
 634         else
 635                 skb_set_transport_header(skb, -hdr_len);
 636 
 637         err = nexthdr;
 638 
 639 out_free:
 640         kfree(work_iph);
 641 out:
 642         return err;
 643 }
 644 
 645 static int ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 646                    u8 type, u8 code, int offset, __be32 info)
 647 {
 648         struct net *net = dev_net(skb->dev);
 649         struct ipv6hdr *iph = (struct ipv6hdr *)skb->data;
 650         struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+offset);
 651         struct xfrm_state *x;
 652 
 653         if (type != ICMPV6_PKT_TOOBIG &&
 654             type != NDISC_REDIRECT)
 655                 return 0;
 656 
 657         x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
 658         if (!x)
 659                 return 0;
 660 
 661         if (type == NDISC_REDIRECT)
 662                 ip6_redirect(skb, net, skb->dev->ifindex, 0,
 663                              sock_net_uid(net, NULL));
 664         else
 665                 ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));
 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         xfrm_unregister_type(&ah6_type, AF_INET6);
 797 }
 798 
 799 module_init(ah6_init);
 800 module_exit(ah6_fini);
 801 
 802 MODULE_LICENSE("GPL");
 803 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_AH);