linux/net/ipv6/ah6.c
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   1/*
   2 * Copyright (C)2002 USAGI/WIDE Project
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License as published by
   6 * the Free Software Foundation; either version 2 of the License, or
   7 * (at your option) any later version.
   8 *
   9 * This program is distributed in the hope that it will be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write to the Free Software
  16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17 *
  18 * Authors
  19 *
  20 *      Mitsuru KANDA @USAGI       : IPv6 Support
  21 *      Kazunori MIYAZAWA @USAGI   :
  22 *      Kunihiro Ishiguro <kunihiro@ipinfusion.com>
  23 *
  24 *      This file is derived from net/ipv4/ah.c.
  25 */
  26
  27#define pr_fmt(fmt) "IPv6: " fmt
  28
  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
  46struct tmp_ext {
  47#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
  48                struct in6_addr saddr;
  49#endif
  50                struct in6_addr daddr;
  51                char hdrs[0];
  52};
  53
  54struct 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
  61static 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
  80static inline struct tmp_ext *ah_tmp_ext(void *base)
  81{
  82        return base + IPV6HDR_BASELEN;
  83}
  84
  85static inline u8 *ah_tmp_auth(u8 *tmp, unsigned int offset)
  86{
  87        return tmp + offset;
  88}
  89
  90static 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
  96static 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
 109static 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
 117static 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
 151bad:
 152        return false;
 153}
 154
 155#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 156/**
 157 *      ipv6_rearrange_destopt - rearrange IPv6 destination options header
 158 *      @iph: IPv6 header
 159 *      @destopt: destionation options header
 160 */
 161static 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 */
 210bad:
 211        return;
 212}
 213#else
 214static 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 */
 226static 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
 256static 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                                LIMIT_NETDEBUG(
 277                                        KERN_WARNING "overrun %sopts\n",
 278                                        nexthdr == NEXTHDR_HOP ?
 279                                                "hop" : "dest");
 280                                return -EINVAL;
 281                        }
 282                        break;
 283
 284                case NEXTHDR_ROUTING:
 285                        ipv6_rearrange_rthdr(iph, exthdr.rth);
 286                        break;
 287
 288                default :
 289                        return 0;
 290                }
 291
 292                nexthdr = exthdr.opth->nexthdr;
 293                exthdr.raw += ipv6_optlen(exthdr.opth);
 294        }
 295
 296        return 0;
 297}
 298
 299static void ah6_output_done(struct crypto_async_request *base, int err)
 300{
 301        int extlen;
 302        u8 *iph_base;
 303        u8 *icv;
 304        struct sk_buff *skb = base->data;
 305        struct xfrm_state *x = skb_dst(skb)->xfrm;
 306        struct ah_data *ahp = x->data;
 307        struct ipv6hdr *top_iph = ipv6_hdr(skb);
 308        struct ip_auth_hdr *ah = ip_auth_hdr(skb);
 309        struct tmp_ext *iph_ext;
 310
 311        extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
 312        if (extlen)
 313                extlen += sizeof(*iph_ext);
 314
 315        iph_base = AH_SKB_CB(skb)->tmp;
 316        iph_ext = ah_tmp_ext(iph_base);
 317        icv = ah_tmp_icv(ahp->ahash, iph_ext, extlen);
 318
 319        memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
 320        memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
 321
 322        if (extlen) {
 323#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 324                memcpy(&top_iph->saddr, iph_ext, extlen);
 325#else
 326                memcpy(&top_iph->daddr, iph_ext, extlen);
 327#endif
 328        }
 329
 330        kfree(AH_SKB_CB(skb)->tmp);
 331        xfrm_output_resume(skb, err);
 332}
 333
 334static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
 335{
 336        int err;
 337        int nfrags;
 338        int extlen;
 339        u8 *iph_base;
 340        u8 *icv;
 341        u8 nexthdr;
 342        struct sk_buff *trailer;
 343        struct crypto_ahash *ahash;
 344        struct ahash_request *req;
 345        struct scatterlist *sg;
 346        struct ipv6hdr *top_iph;
 347        struct ip_auth_hdr *ah;
 348        struct ah_data *ahp;
 349        struct tmp_ext *iph_ext;
 350
 351        ahp = x->data;
 352        ahash = ahp->ahash;
 353
 354        if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
 355                goto out;
 356        nfrags = err;
 357
 358        skb_push(skb, -skb_network_offset(skb));
 359        extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
 360        if (extlen)
 361                extlen += sizeof(*iph_ext);
 362
 363        err = -ENOMEM;
 364        iph_base = ah_alloc_tmp(ahash, nfrags, IPV6HDR_BASELEN + extlen);
 365        if (!iph_base)
 366                goto out;
 367
 368        iph_ext = ah_tmp_ext(iph_base);
 369        icv = ah_tmp_icv(ahash, iph_ext, extlen);
 370        req = ah_tmp_req(ahash, icv);
 371        sg = ah_req_sg(ahash, req);
 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 defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 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);
 416        skb_to_sgvec(skb, sg, 0, skb->len);
 417
 418        ahash_request_set_crypt(req, sg, icv, skb->len);
 419        ahash_request_set_callback(req, 0, ah6_output_done, skb);
 420
 421        AH_SKB_CB(skb)->tmp = iph_base;
 422
 423        err = crypto_ahash_digest(req);
 424        if (err) {
 425                if (err == -EINPROGRESS)
 426                        goto out;
 427
 428                if (err == -EBUSY)
 429                        err = NET_XMIT_DROP;
 430                goto out_free;
 431        }
 432
 433        memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
 434        memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
 435
 436        if (extlen) {
 437#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 438                memcpy(&top_iph->saddr, iph_ext, extlen);
 439#else
 440                memcpy(&top_iph->daddr, iph_ext, extlen);
 441#endif
 442        }
 443
 444out_free:
 445        kfree(iph_base);
 446out:
 447        return err;
 448}
 449
 450static void ah6_input_done(struct crypto_async_request *base, int err)
 451{
 452        u8 *auth_data;
 453        u8 *icv;
 454        u8 *work_iph;
 455        struct sk_buff *skb = base->data;
 456        struct xfrm_state *x = xfrm_input_state(skb);
 457        struct ah_data *ahp = x->data;
 458        struct ip_auth_hdr *ah = ip_auth_hdr(skb);
 459        int hdr_len = skb_network_header_len(skb);
 460        int ah_hlen = (ah->hdrlen + 2) << 2;
 461
 462        work_iph = AH_SKB_CB(skb)->tmp;
 463        auth_data = ah_tmp_auth(work_iph, hdr_len);
 464        icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);
 465
 466        err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
 467        if (err)
 468                goto out;
 469
 470        err = ah->nexthdr;
 471
 472        skb->network_header += ah_hlen;
 473        memcpy(skb_network_header(skb), work_iph, hdr_len);
 474        __skb_pull(skb, ah_hlen + hdr_len);
 475        skb_set_transport_header(skb, -hdr_len);
 476out:
 477        kfree(AH_SKB_CB(skb)->tmp);
 478        xfrm_input_resume(skb, err);
 479}
 480
 481
 482
 483static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
 484{
 485        /*
 486         * Before process AH
 487         * [IPv6][Ext1][Ext2][AH][Dest][Payload]
 488         * |<-------------->| hdr_len
 489         *
 490         * To erase AH:
 491         * Keeping copy of cleared headers. After AH processing,
 492         * Moving the pointer of skb->network_header by using skb_pull as long
 493         * as AH header length. Then copy back the copy as long as hdr_len
 494         * If destination header following AH exists, copy it into after [Ext2].
 495         *
 496         * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
 497         * There is offset of AH before IPv6 header after the process.
 498         */
 499
 500        u8 *auth_data;
 501        u8 *icv;
 502        u8 *work_iph;
 503        struct sk_buff *trailer;
 504        struct crypto_ahash *ahash;
 505        struct ahash_request *req;
 506        struct scatterlist *sg;
 507        struct ip_auth_hdr *ah;
 508        struct ipv6hdr *ip6h;
 509        struct ah_data *ahp;
 510        u16 hdr_len;
 511        u16 ah_hlen;
 512        int nexthdr;
 513        int nfrags;
 514        int err = -ENOMEM;
 515
 516        if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
 517                goto out;
 518
 519        /* We are going to _remove_ AH header to keep sockets happy,
 520         * so... Later this can change. */
 521        if (skb_cloned(skb) &&
 522            pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 523                goto out;
 524
 525        skb->ip_summed = CHECKSUM_NONE;
 526
 527        hdr_len = skb_network_header_len(skb);
 528        ah = (struct ip_auth_hdr *)skb->data;
 529        ahp = x->data;
 530        ahash = ahp->ahash;
 531
 532        nexthdr = ah->nexthdr;
 533        ah_hlen = (ah->hdrlen + 2) << 2;
 534
 535        if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
 536            ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
 537                goto out;
 538
 539        if (!pskb_may_pull(skb, ah_hlen))
 540                goto out;
 541
 542
 543        if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
 544                goto out;
 545        nfrags = err;
 546
 547        ah = (struct ip_auth_hdr *)skb->data;
 548        ip6h = ipv6_hdr(skb);
 549
 550        skb_push(skb, hdr_len);
 551
 552        work_iph = ah_alloc_tmp(ahash, nfrags, hdr_len + ahp->icv_trunc_len);
 553        if (!work_iph)
 554                goto out;
 555
 556        auth_data = ah_tmp_auth(work_iph, hdr_len);
 557        icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len);
 558        req = ah_tmp_req(ahash, icv);
 559        sg = ah_req_sg(ahash, req);
 560
 561        memcpy(work_iph, ip6h, hdr_len);
 562        memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
 563        memset(ah->auth_data, 0, ahp->icv_trunc_len);
 564
 565        if (ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN))
 566                goto out_free;
 567
 568        ip6h->priority    = 0;
 569        ip6h->flow_lbl[0] = 0;
 570        ip6h->flow_lbl[1] = 0;
 571        ip6h->flow_lbl[2] = 0;
 572        ip6h->hop_limit   = 0;
 573
 574        sg_init_table(sg, nfrags);
 575        skb_to_sgvec(skb, sg, 0, skb->len);
 576
 577        ahash_request_set_crypt(req, sg, icv, skb->len);
 578        ahash_request_set_callback(req, 0, ah6_input_done, skb);
 579
 580        AH_SKB_CB(skb)->tmp = work_iph;
 581
 582        err = crypto_ahash_digest(req);
 583        if (err) {
 584                if (err == -EINPROGRESS)
 585                        goto out;
 586
 587                goto out_free;
 588        }
 589
 590        err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
 591        if (err)
 592                goto out_free;
 593
 594        skb->network_header += ah_hlen;
 595        memcpy(skb_network_header(skb), work_iph, hdr_len);
 596        skb->transport_header = skb->network_header;
 597        __skb_pull(skb, ah_hlen + hdr_len);
 598
 599        err = nexthdr;
 600
 601out_free:
 602        kfree(work_iph);
 603out:
 604        return err;
 605}
 606
 607static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 608                    u8 type, u8 code, int offset, __be32 info)
 609{
 610        struct net *net = dev_net(skb->dev);
 611        struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 612        struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+offset);
 613        struct xfrm_state *x;
 614
 615        if (type != ICMPV6_DEST_UNREACH &&
 616            type != ICMPV6_PKT_TOOBIG &&
 617            type != NDISC_REDIRECT)
 618                return;
 619
 620        x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
 621        if (!x)
 622                return;
 623
 624        if (type == NDISC_REDIRECT)
 625                ip6_redirect(skb, net, 0, 0);
 626        else
 627                ip6_update_pmtu(skb, net, info, 0, 0);
 628        xfrm_state_put(x);
 629}
 630
 631static int ah6_init_state(struct xfrm_state *x)
 632{
 633        struct ah_data *ahp = NULL;
 634        struct xfrm_algo_desc *aalg_desc;
 635        struct crypto_ahash *ahash;
 636
 637        if (!x->aalg)
 638                goto error;
 639
 640        if (x->encap)
 641                goto error;
 642
 643        ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
 644        if (ahp == NULL)
 645                return -ENOMEM;
 646
 647        ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
 648        if (IS_ERR(ahash))
 649                goto error;
 650
 651        ahp->ahash = ahash;
 652        if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
 653                               (x->aalg->alg_key_len + 7) / 8))
 654                goto error;
 655
 656        /*
 657         * Lookup the algorithm description maintained by xfrm_algo,
 658         * verify crypto transform properties, and store information
 659         * we need for AH processing.  This lookup cannot fail here
 660         * after a successful crypto_alloc_hash().
 661         */
 662        aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
 663        BUG_ON(!aalg_desc);
 664
 665        if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
 666            crypto_ahash_digestsize(ahash)) {
 667                pr_info("AH: %s digestsize %u != %hu\n",
 668                        x->aalg->alg_name, crypto_ahash_digestsize(ahash),
 669                        aalg_desc->uinfo.auth.icv_fullbits/8);
 670                goto error;
 671        }
 672
 673        ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
 674        ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
 675
 676        BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
 677
 678        x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
 679                                          ahp->icv_trunc_len);
 680        switch (x->props.mode) {
 681        case XFRM_MODE_BEET:
 682        case XFRM_MODE_TRANSPORT:
 683                break;
 684        case XFRM_MODE_TUNNEL:
 685                x->props.header_len += sizeof(struct ipv6hdr);
 686                break;
 687        default:
 688                goto error;
 689        }
 690        x->data = ahp;
 691
 692        return 0;
 693
 694error:
 695        if (ahp) {
 696                crypto_free_ahash(ahp->ahash);
 697                kfree(ahp);
 698        }
 699        return -EINVAL;
 700}
 701
 702static void ah6_destroy(struct xfrm_state *x)
 703{
 704        struct ah_data *ahp = x->data;
 705
 706        if (!ahp)
 707                return;
 708
 709        crypto_free_ahash(ahp->ahash);
 710        kfree(ahp);
 711}
 712
 713static const struct xfrm_type ah6_type =
 714{
 715        .description    = "AH6",
 716        .owner          = THIS_MODULE,
 717        .proto          = IPPROTO_AH,
 718        .flags          = XFRM_TYPE_REPLAY_PROT,
 719        .init_state     = ah6_init_state,
 720        .destructor     = ah6_destroy,
 721        .input          = ah6_input,
 722        .output         = ah6_output,
 723        .hdr_offset     = xfrm6_find_1stfragopt,
 724};
 725
 726static const struct inet6_protocol ah6_protocol = {
 727        .handler        =       xfrm6_rcv,
 728        .err_handler    =       ah6_err,
 729        .flags          =       INET6_PROTO_NOPOLICY,
 730};
 731
 732static int __init ah6_init(void)
 733{
 734        if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
 735                pr_info("%s: can't add xfrm type\n", __func__);
 736                return -EAGAIN;
 737        }
 738
 739        if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) {
 740                pr_info("%s: can't add protocol\n", __func__);
 741                xfrm_unregister_type(&ah6_type, AF_INET6);
 742                return -EAGAIN;
 743        }
 744
 745        return 0;
 746}
 747
 748static void __exit ah6_fini(void)
 749{
 750        if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0)
 751                pr_info("%s: can't remove protocol\n", __func__);
 752
 753        if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
 754                pr_info("%s: can't remove xfrm type\n", __func__);
 755
 756}
 757
 758module_init(ah6_init);
 759module_exit(ah6_fini);
 760
 761MODULE_LICENSE("GPL");
 762MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_AH);
 763
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