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/algapi.h>
  29 #include <crypto/hash.h>
  30 #include <linux/module.h>
  31 #include <linux/slab.h>
  32 #include <net/ip.h>
  33 #include <net/ah.h>
  34 #include <linux/crypto.h>
  35 #include <linux/pfkeyv2.h>
  36 #include <linux/string.h>
  37 #include <linux/scatterlist.h>
  38 #include <net/ip6_route.h>
  39 #include <net/icmp.h>
  40 #include <net/ipv6.h>
  41 #include <net/protocol.h>
  42 #include <net/xfrm.h>
  43
  44 #define IPV6HDR_BASELEN 8
  45
  46 struct tmp_ext {
  47 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  48                 struct in6_addr saddr;
  49 #endif
  50                 struct in6_addr daddr;
  51                 char hdrs[0];
  52 };
  53
  54 struct ah_skb_cb {
  55         struct xfrm_skb_cb xfrm;
  56         void *tmp;
  57 };
  58
  59 #define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0]))
  60
  61 static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags,
  62                           unsigned int size)
  63 {
  64         unsigned int len;
  65
  66         len = size + crypto_ahash_digestsize(ahash) +
  67               (crypto_ahash_alignmask(ahash) &
  68                ~(crypto_tfm_ctx_alignment() - 1));
  69
  70         len = ALIGN(len, crypto_tfm_ctx_alignment());
  71
  72         len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash);
  73         len = ALIGN(len, __alignof__(struct scatterlist));
  74
  75         len += sizeof(struct scatterlist) * nfrags;
  76
  77         return kmalloc(len, GFP_ATOMIC);
  78 }
  79
  80 static inline struct tmp_ext *ah_tmp_ext(void *base)
  81 {
  82         return base + IPV6HDR_BASELEN;
  83 }
  84
  85 static inline u8 *ah_tmp_auth(u8 *tmp, unsigned int offset)
  86 {
  87         return tmp + offset;
  88 }
  89
  90 static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp,
  91                              unsigned int offset)
  92 {
  93         return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1);
  94 }
  95
  96 static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash,
  97                                                u8 *icv)
  98 {
  99         struct ahash_request *req;
 100
 101         req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash),
 102                                 crypto_tfm_ctx_alignment());
 103
 104         ahash_request_set_tfm(req, ahash);
 105
 106         return req;
 107 }
 108
 109 static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash,
 110                                              struct ahash_request *req)
 111 {
 112         return (void *)ALIGN((unsigned long)(req + 1) +
 113                              crypto_ahash_reqsize(ahash),
 114                              __alignof__(struct scatterlist));
 115 }
 116
 117 static bool zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr)
 118 {
 119         u8 *opt = (u8 *)opthdr;
 120         int len = ipv6_optlen(opthdr);
 121         int off = 0;
 122         int optlen = 0;
 123
 124         off += 2;
 125         len -= 2;
 126
 127         while (len > 0) {
 128
 129                 switch (opt[off]) {
 130
 131                 case IPV6_TLV_PAD1:
 132                         optlen = 1;
 133                         break;
 134                 default:
 135                         if (len < 2)
 136                                 goto bad;
 137                         optlen = opt[off+1]+2;
 138                         if (len < optlen)
 139                                 goto bad;
 140                         if (opt[off] & 0x20)
 141                                 memset(&opt[off+2], 0, opt[off+1]);
 142                         break;
 143                 }
 144
 145                 off += optlen;
 146                 len -= optlen;
 147         }
 148         if (len == 0)
 149                 return true;
 150
 151 bad:
 152         return false;
 153 }
 154
 155 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 156 /**
 157  *      ipv6_rearrange_destopt - rearrange IPv6 destination options header
 158  *      @iph: IPv6 header
 159  *      @destopt: destionation options header
 160  */
 161 static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt)
 162 {
 163         u8 *opt = (u8 *)destopt;
 164         int len = ipv6_optlen(destopt);
 165         int off = 0;
 166         int optlen = 0;
 167
 168         off += 2;
 169         len -= 2;
 170
 171         while (len > 0) {
 172
 173                 switch (opt[off]) {
 174
 175                 case IPV6_TLV_PAD1:
 176                         optlen = 1;
 177                         break;
 178                 default:
 179                         if (len < 2)
 180                                 goto bad;
 181                         optlen = opt[off+1]+2;
 182                         if (len < optlen)
 183                                 goto bad;
 184
 185                         /* Rearrange the source address in @iph and the
 186                          * addresses in home address option for final source.
 187                          * See 11.3.2 of RFC 3775 for details.
 188                          */
 189                         if (opt[off] == IPV6_TLV_HAO) {
 190                                 struct in6_addr final_addr;
 191                                 struct ipv6_destopt_hao *hao;
 192
 193                                 hao = (struct ipv6_destopt_hao *)&opt[off];
 194                                 if (hao->length != sizeof(hao->addr)) {
 195                                         net_warn_ratelimited("destopt hao: invalid header length: %u\n",
 196                                                              hao->length);
 197                                         goto bad;
 198                                 }
 199                                 final_addr = hao->addr;
 200                                 hao->addr = iph->saddr;
 201                                 iph->saddr = final_addr;
 202                         }
 203                         break;
 204                 }
 205
 206                 off += optlen;
 207                 len -= optlen;
 208         }
 209         /* Note: ok if len == 0 */
 210 bad:
 211         return;
 212 }
 213 #else
 214 static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt) {}
 215 #endif
 216
 217 /**
 218  *      ipv6_rearrange_rthdr - rearrange IPv6 routing header
 219  *      @iph: IPv6 header
 220  *      @rthdr: routing header
 221  *
 222  *      Rearrange the destination address in @iph and the addresses in @rthdr
 223  *      so that they appear in the order they will at the final destination.
 224  *      See Appendix A2 of RFC 2402 for details.
 225  */
 226 static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr)
 227 {
 228         int segments, segments_left;
 229         struct in6_addr *addrs;
 230         struct in6_addr final_addr;
 231
 232         segments_left = rthdr->segments_left;
 233         if (segments_left == 0)
 234                 return;
 235         rthdr->segments_left = 0;
 236
 237         /* The value of rthdr->hdrlen has been verified either by the system
 238          * call if it is locally generated, or by ipv6_rthdr_rcv() for incoming
 239          * packets.  So we can assume that it is even and that segments is
 240          * greater than or equal to segments_left.
 241          *
 242          * For the same reason we can assume that this option is of type 0.
 243          */
 244         segments = rthdr->hdrlen >> 1;
 245
 246         addrs = ((struct rt0_hdr *)rthdr)->addr;
 247         final_addr = addrs[segments - 1];
 248
 249         addrs += segments - segments_left;
 250         memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs));
 251
 252         addrs[0] = iph->daddr;
 253         iph->daddr = final_addr;
 254 }
 255
 256 static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len, int dir)
 257 {
 258         union {
 259                 struct ipv6hdr *iph;
 260                 struct ipv6_opt_hdr *opth;
 261                 struct ipv6_rt_hdr *rth;
 262                 char *raw;
 263         } exthdr = { .iph = iph };
 264         char *end = exthdr.raw + len;
 265         int nexthdr = iph->nexthdr;
 266
 267         exthdr.iph++;
 268
 269         while (exthdr.raw < end) {
 270                 switch (nexthdr) {
 271                 case NEXTHDR_DEST:
 272                         if (dir == XFRM_POLICY_OUT)
 273                                 ipv6_rearrange_destopt(iph, exthdr.opth);
 274                 case NEXTHDR_HOP:
 275                         if (!zero_out_mutable_opts(exthdr.opth)) {
 276                                 net_dbg_ratelimited("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         int seqhi_len = 0;
 350         __be32 *seqhi;
 351         int sglists = 0;
 352         struct scatterlist *seqhisg;
 353
 354         ahp = x->data;
 355         ahash = ahp->ahash;
 356
 357         err = skb_cow_data(skb, 0, &trailer);
 358         if (err < 0)
 359                 goto out;
 360         nfrags = err;
 361
 362         skb_push(skb, -skb_network_offset(skb));
 363         extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
 364         if (extlen)
 365                 extlen += sizeof(*iph_ext);
 366
 367         if (x->props.flags & XFRM_STATE_ESN) {
 368                 sglists = 1;
 369                 seqhi_len = sizeof(*seqhi);
 370         }
 371         err = -ENOMEM;
 372         iph_base = ah_alloc_tmp(ahash, nfrags + sglists, IPV6HDR_BASELEN +
 373                                 extlen + seqhi_len);
 374         if (!iph_base)
 375                 goto out;
 376
 377         iph_ext = ah_tmp_ext(iph_base);
 378         seqhi = (__be32 *)((char *)iph_ext + extlen);
 379         icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
 380         req = ah_tmp_req(ahash, icv);
 381         sg = ah_req_sg(ahash, req);
 382         seqhisg = sg + nfrags;
 383
 384         ah = ip_auth_hdr(skb);
 385         memset(ah->auth_data, 0, ahp->icv_trunc_len);
 386
 387         top_iph = ipv6_hdr(skb);
 388         top_iph->payload_len = htons(skb->len - sizeof(*top_iph));
 389
 390         nexthdr = *skb_mac_header(skb);
 391         *skb_mac_header(skb) = IPPROTO_AH;
 392
 393         /* When there are no extension headers, we only need to save the first
 394          * 8 bytes of the base IP header.
 395          */
 396         memcpy(iph_base, top_iph, IPV6HDR_BASELEN);
 397
 398         if (extlen) {
 399 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 400                 memcpy(iph_ext, &top_iph->saddr, extlen);
 401 #else
 402                 memcpy(iph_ext, &top_iph->daddr, extlen);
 403 #endif
 404                 err = ipv6_clear_mutable_options(top_iph,
 405                                                  extlen - sizeof(*iph_ext) +
 406                                                  sizeof(*top_iph),
 407                                                  XFRM_POLICY_OUT);
 408                 if (err)
 409                         goto out_free;
 410         }
 411
 412         ah->nexthdr = nexthdr;
 413
 414         top_iph->priority    = 0;
 415         top_iph->flow_lbl[0] = 0;
 416         top_iph->flow_lbl[1] = 0;
 417         top_iph->flow_lbl[2] = 0;
 418         top_iph->hop_limit   = 0;
 419
 420         ah->hdrlen  = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
 421
 422         ah->reserved = 0;
 423         ah->spi = x->id.spi;
 424         ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
 425
 426         sg_init_table(sg, nfrags + sglists);
 427         err = skb_to_sgvec_nomark(skb, sg, 0, skb->len);
 428         if (unlikely(err < 0))
 429                 goto out_free;
 430
 431         if (x->props.flags & XFRM_STATE_ESN) {
 432                 /* Attach seqhi sg right after packet payload */
 433                 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
 434                 sg_set_buf(seqhisg, seqhi, seqhi_len);
 435         }
 436         ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
 437         ahash_request_set_callback(req, 0, ah6_output_done, skb);
 438
 439         AH_SKB_CB(skb)->tmp = iph_base;
 440
 441         err = crypto_ahash_digest(req);
 442         if (err) {
 443                 if (err == -EINPROGRESS)
 444                         goto out;
 445
 446                 if (err == -EBUSY)
 447                         err = NET_XMIT_DROP;
 448                 goto out_free;
 449         }
 450
 451         memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
 452         memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
 453
 454         if (extlen) {
 455 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 456                 memcpy(&top_iph->saddr, iph_ext, extlen);
 457 #else
 458                 memcpy(&top_iph->daddr, iph_ext, extlen);
 459 #endif
 460         }
 461
 462 out_free:
 463         kfree(iph_base);
 464 out:
 465         return err;
 466 }
 467
 468 static void ah6_input_done(struct crypto_async_request *base, int err)
 469 {
 470         u8 *auth_data;
 471         u8 *icv;
 472         u8 *work_iph;
 473         struct sk_buff *skb = base->data;
 474         struct xfrm_state *x = xfrm_input_state(skb);
 475         struct ah_data *ahp = x->data;
 476         struct ip_auth_hdr *ah = ip_auth_hdr(skb);
 477         int hdr_len = skb_network_header_len(skb);
 478         int ah_hlen = (ah->hdrlen + 2) << 2;
 479
 480         if (err)
 481                 goto out;
 482
 483         work_iph = AH_SKB_CB(skb)->tmp;
 484         auth_data = ah_tmp_auth(work_iph, hdr_len);
 485         icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);
 486
 487         err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
 488         if (err)
 489                 goto out;
 490
 491         err = ah->nexthdr;
 492
 493         skb->network_header += ah_hlen;
 494         memcpy(skb_network_header(skb), work_iph, hdr_len);
 495         __skb_pull(skb, ah_hlen + hdr_len);
 496         if (x->props.mode == XFRM_MODE_TUNNEL)
 497                 skb_reset_transport_header(skb);
 498         else
 499                 skb_set_transport_header(skb, -hdr_len);
 500 out:
 501         kfree(AH_SKB_CB(skb)->tmp);
 502         xfrm_input_resume(skb, err);
 503 }
 504
 505
 506
 507 static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
 508 {
 509         /*
 510          * Before process AH
 511          * [IPv6][Ext1][Ext2][AH][Dest][Payload]
 512          * |<-------------->| hdr_len
 513          *
 514          * To erase AH:
 515          * Keeping copy of cleared headers. After AH processing,
 516          * Moving the pointer of skb->network_header by using skb_pull as long
 517          * as AH header length. Then copy back the copy as long as hdr_len
 518          * If destination header following AH exists, copy it into after [Ext2].
 519          *
 520          * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
 521          * There is offset of AH before IPv6 header after the process.
 522          */
 523
 524         u8 *auth_data;
 525         u8 *icv;
 526         u8 *work_iph;
 527         struct sk_buff *trailer;
 528         struct crypto_ahash *ahash;
 529         struct ahash_request *req;
 530         struct scatterlist *sg;
 531         struct ip_auth_hdr *ah;
 532         struct ipv6hdr *ip6h;
 533         struct ah_data *ahp;
 534         u16 hdr_len;
 535         u16 ah_hlen;
 536         int nexthdr;
 537         int nfrags;
 538         int err = -ENOMEM;
 539         int seqhi_len = 0;
 540         __be32 *seqhi;
 541         int sglists = 0;
 542         struct scatterlist *seqhisg;
 543
 544         if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
 545                 goto out;
 546
 547         /* We are going to _remove_ AH header to keep sockets happy,
 548          * so... Later this can change. */
 549         if (skb_unclone(skb, GFP_ATOMIC))
 550                 goto out;
 551
 552         skb->ip_summed = CHECKSUM_NONE;
 553
 554         hdr_len = skb_network_header_len(skb);
 555         ah = (struct ip_auth_hdr *)skb->data;
 556         ahp = x->data;
 557         ahash = ahp->ahash;
 558
 559         nexthdr = ah->nexthdr;
 560         ah_hlen = (ah->hdrlen + 2) << 2;
 561
 562         if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
 563             ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
 564                 goto out;
 565
 566         if (!pskb_may_pull(skb, ah_hlen))
 567                 goto out;
 568
 569         err = skb_cow_data(skb, 0, &trailer);
 570         if (err < 0)
 571                 goto out;
 572         nfrags = err;
 573
 574         ah = (struct ip_auth_hdr *)skb->data;
 575         ip6h = ipv6_hdr(skb);
 576
 577         skb_push(skb, hdr_len);
 578
 579         if (x->props.flags & XFRM_STATE_ESN) {
 580                 sglists = 1;
 581                 seqhi_len = sizeof(*seqhi);
 582         }
 583
 584         work_iph = ah_alloc_tmp(ahash, nfrags + sglists, hdr_len +
 585                                 ahp->icv_trunc_len + seqhi_len);
 586         if (!work_iph) {
 587                 err = -ENOMEM;
 588                 goto out;
 589         }
 590
 591         auth_data = ah_tmp_auth((u8 *)work_iph, hdr_len);
 592         seqhi = (__be32 *)(auth_data + ahp->icv_trunc_len);
 593         icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
 594         req = ah_tmp_req(ahash, icv);
 595         sg = ah_req_sg(ahash, req);
 596         seqhisg = sg + nfrags;
 597
 598         memcpy(work_iph, ip6h, hdr_len);
 599         memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
 600         memset(ah->auth_data, 0, ahp->icv_trunc_len);
 601
 602         if (ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN))
 603                 goto out_free;
 604
 605         ip6h->priority    = 0;
 606         ip6h->flow_lbl[0] = 0;
 607         ip6h->flow_lbl[1] = 0;
 608         ip6h->flow_lbl[2] = 0;
 609         ip6h->hop_limit   = 0;
 610
 611         sg_init_table(sg, nfrags + sglists);
 612         err = skb_to_sgvec_nomark(skb, sg, 0, skb->len);
 613         if (unlikely(err < 0))
 614                 goto out_free;
 615
 616         if (x->props.flags & XFRM_STATE_ESN) {
 617                 /* Attach seqhi sg right after packet payload */
 618                 *seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
 619                 sg_set_buf(seqhisg, seqhi, seqhi_len);
 620         }
 621
 622         ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
 623         ahash_request_set_callback(req, 0, ah6_input_done, skb);
 624
 625         AH_SKB_CB(skb)->tmp = work_iph;
 626
 627         err = crypto_ahash_digest(req);
 628         if (err) {
 629                 if (err == -EINPROGRESS)
 630                         goto out;
 631
 632                 goto out_free;
 633         }
 634
 635         err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
 636         if (err)
 637                 goto out_free;
 638
 639         skb->network_header += ah_hlen;
 640         memcpy(skb_network_header(skb), work_iph, hdr_len);
 641         __skb_pull(skb, ah_hlen + hdr_len);
 642
 643         if (x->props.mode == XFRM_MODE_TUNNEL)
 644                 skb_reset_transport_header(skb);
 645         else
 646                 skb_set_transport_header(skb, -hdr_len);
 647
 648         err = nexthdr;
 649
 650 out_free:
 651         kfree(work_iph);
 652 out:
 653         return err;
 654 }
 655
 656 static int ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 657                    u8 type, u8 code, int offset, __be32 info)
 658 {
 659         struct net *net = dev_net(skb->dev);
 660         struct ipv6hdr *iph = (struct ipv6hdr *)skb->data;
 661         struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+offset);
 662         struct xfrm_state *x;
 663
 664         if (type != ICMPV6_PKT_TOOBIG &&
 665             type != NDISC_REDIRECT)
 666                 return 0;
 667
 668         x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
 669         if (!x)
 670                 return 0;
 671
 672         if (type == NDISC_REDIRECT)
 673                 ip6_redirect(skb, net, skb->dev->ifindex, 0,
 674                              sock_net_uid(net, NULL));
 675         else
 676                 ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));
 677         xfrm_state_put(x);
 678
 679         return 0;
 680 }
 681
 682 static int ah6_init_state(struct xfrm_state *x)
 683 {
 684         struct ah_data *ahp = NULL;
 685         struct xfrm_algo_desc *aalg_desc;
 686         struct crypto_ahash *ahash;
 687
 688         if (!x->aalg)
 689                 goto error;
 690
 691         if (x->encap)
 692                 goto error;
 693
 694         ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
 695         if (!ahp)
 696                 return -ENOMEM;
 697
 698         ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
 699         if (IS_ERR(ahash))
 700                 goto error;
 701
 702         ahp->ahash = ahash;
 703         if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
 704                                (x->aalg->alg_key_len + 7) / 8))
 705                 goto error;
 706
 707         /*
 708          * Lookup the algorithm description maintained by xfrm_algo,
 709          * verify crypto transform properties, and store information
 710          * we need for AH processing.  This lookup cannot fail here
 711          * after a successful crypto_alloc_hash().
 712          */
 713         aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
 714         BUG_ON(!aalg_desc);
 715
 716         if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
 717             crypto_ahash_digestsize(ahash)) {
 718                 pr_info("AH: %s digestsize %u != %hu\n",
 719                         x->aalg->alg_name, crypto_ahash_digestsize(ahash),
 720                         aalg_desc->uinfo.auth.icv_fullbits/8);
 721                 goto error;
 722         }
 723
 724         ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
 725         ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
 726
 727         x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
 728                                           ahp->icv_trunc_len);
 729         switch (x->props.mode) {
 730         case XFRM_MODE_BEET:
 731         case XFRM_MODE_TRANSPORT:
 732                 break;
 733         case XFRM_MODE_TUNNEL:
 734                 x->props.header_len += sizeof(struct ipv6hdr);
 735                 break;
 736         default:
 737                 goto error;
 738         }
 739         x->data = ahp;
 740
 741         return 0;
 742
 743 error:
 744         if (ahp) {
 745                 crypto_free_ahash(ahp->ahash);
 746                 kfree(ahp);
 747         }
 748         return -EINVAL;
 749 }
 750
 751 static void ah6_destroy(struct xfrm_state *x)
 752 {
 753         struct ah_data *ahp = x->data;
 754
 755         if (!ahp)
 756                 return;
 757
 758         crypto_free_ahash(ahp->ahash);
 759         kfree(ahp);
 760 }
 761
 762 static int ah6_rcv_cb(struct sk_buff *skb, int err)
 763 {
 764         return 0;
 765 }
 766
 767 static const struct xfrm_type ah6_type = {
 768         .description    = "AH6",
 769         .owner          = THIS_MODULE,
 770         .proto          = IPPROTO_AH,
 771         .flags          = XFRM_TYPE_REPLAY_PROT,
 772         .init_state     = ah6_init_state,
 773         .destructor     = ah6_destroy,
 774         .input          = ah6_input,
 775         .output         = ah6_output,
 776         .hdr_offset     = xfrm6_find_1stfragopt,
 777 };
 778
 779 static struct xfrm6_protocol ah6_protocol = {
 780         .handler        =       xfrm6_rcv,
 781         .cb_handler     =       ah6_rcv_cb,
 782         .err_handler    =       ah6_err,
 783         .priority       =       0,
 784 };
 785
 786 static int __init ah6_init(void)
 787 {
 788         if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
 789                 pr_info("%s: can't add xfrm type\n", __func__);
 790                 return -EAGAIN;
 791         }
 792
 793         if (xfrm6_protocol_register(&ah6_protocol, IPPROTO_AH) < 0) {
 794                 pr_info("%s: can't add protocol\n", __func__);
 795                 xfrm_unregister_type(&ah6_type, AF_INET6);
 796                 return -EAGAIN;
 797         }
 798
 799         return 0;
 800 }
 801
 802 static void __exit ah6_fini(void)
 803 {
 804         if (xfrm6_protocol_deregister(&ah6_protocol, IPPROTO_AH) < 0)
 805                 pr_info("%s: can't remove protocol\n", __func__);
 806
 807         if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
 808                 pr_info("%s: can't remove xfrm type\n", __func__);
 809
 810 }
 811
 812 module_init(ah6_init);
 813 module_exit(ah6_fini);
 814
 815 MODULE_LICENSE("GPL");
 816 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_AH);