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TOMOYO Linux Cross Reference
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, see <http://www.gnu.org/licenses/>.
 16  *
 17  * Authors
 18  *
 19  *      Mitsuru KANDA @USAGI       : IPv6 Support
 20  *      Kazunori MIYAZAWA @USAGI   :
 21  *      Kunihiro Ishiguro <kunihiro@ipinfusion.com>
 22  *
 23  *      This file is derived from net/ipv4/ah.c.
 24  */
 25 
 26 #define pr_fmt(fmt) "IPv6: " fmt
 27 
 28 #include <crypto/hash.h>
 29 #include <linux/module.h>
 30 #include <linux/slab.h>
 31 #include <net/ip.h>
 32 #include <net/ah.h>
 33 #include <linux/crypto.h>
 34 #include <linux/pfkeyv2.h>
 35 #include <linux/string.h>
 36 #include <linux/scatterlist.h>
 37 #include <net/ip6_route.h>
 38 #include <net/icmp.h>
 39 #include <net/ipv6.h>
 40 #include <net/protocol.h>
 41 #include <net/xfrm.h>
 42 
 43 #define IPV6HDR_BASELEN 8
 44 
 45 struct tmp_ext {
 46 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 47                 struct in6_addr saddr;
 48 #endif
 49                 struct in6_addr daddr;
 50                 char hdrs[0];
 51 };
 52 
 53 struct ah_skb_cb {
 54         struct xfrm_skb_cb xfrm;
 55         void *tmp;
 56 };
 57 
 58 #define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0]))
 59 
 60 static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags,
 61                           unsigned int size)
 62 {
 63         unsigned int len;
 64 
 65         len = size + crypto_ahash_digestsize(ahash) +
 66               (crypto_ahash_alignmask(ahash) &
 67                ~(crypto_tfm_ctx_alignment() - 1));
 68 
 69         len = ALIGN(len, crypto_tfm_ctx_alignment());
 70 
 71         len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash);
 72         len = ALIGN(len, __alignof__(struct scatterlist));
 73 
 74         len += sizeof(struct scatterlist) * nfrags;
 75 
 76         return kmalloc(len, GFP_ATOMIC);
 77 }
 78 
 79 static inline struct tmp_ext *ah_tmp_ext(void *base)
 80 {
 81         return base + IPV6HDR_BASELEN;
 82 }
 83 
 84 static inline u8 *ah_tmp_auth(u8 *tmp, unsigned int offset)
 85 {
 86         return tmp + offset;
 87 }
 88 
 89 static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp,
 90                              unsigned int offset)
 91 {
 92         return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1);
 93 }
 94 
 95 static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash,
 96                                                u8 *icv)
 97 {
 98         struct ahash_request *req;
 99 
100         req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash),
101                                 crypto_tfm_ctx_alignment());
102 
103         ahash_request_set_tfm(req, ahash);
104 
105         return req;
106 }
107 
108 static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash,
109                                              struct ahash_request *req)
110 {
111         return (void *)ALIGN((unsigned long)(req + 1) +
112                              crypto_ahash_reqsize(ahash),
113                              __alignof__(struct scatterlist));
114 }
115 
116 static bool zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr)
117 {
118         u8 *opt = (u8 *)opthdr;
119         int len = ipv6_optlen(opthdr);
120         int off = 0;
121         int optlen = 0;
122 
123         off += 2;
124         len -= 2;
125 
126         while (len > 0) {
127 
128                 switch (opt[off]) {
129 
130                 case IPV6_TLV_PAD1:
131                         optlen = 1;
132                         break;
133                 default:
134                         if (len < 2)
135                                 goto bad;
136                         optlen = opt[off+1]+2;
137                         if (len < optlen)
138                                 goto bad;
139                         if (opt[off] & 0x20)
140                                 memset(&opt[off+2], 0, opt[off+1]);
141                         break;
142                 }
143 
144                 off += optlen;
145                 len -= optlen;
146         }
147         if (len == 0)
148                 return true;
149 
150 bad:
151         return false;
152 }
153 
154 #if IS_ENABLED(CONFIG_IPV6_MIP6)
155 /**
156  *      ipv6_rearrange_destopt - rearrange IPv6 destination options header
157  *      @iph: IPv6 header
158  *      @destopt: destionation options header
159  */
160 static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt)
161 {
162         u8 *opt = (u8 *)destopt;
163         int len = ipv6_optlen(destopt);
164         int off = 0;
165         int optlen = 0;
166 
167         off += 2;
168         len -= 2;
169 
170         while (len > 0) {
171 
172                 switch (opt[off]) {
173 
174                 case IPV6_TLV_PAD1:
175                         optlen = 1;
176                         break;
177                 default:
178                         if (len < 2)
179                                 goto bad;
180                         optlen = opt[off+1]+2;
181                         if (len < optlen)
182                                 goto bad;
183 
184                         /* Rearrange the source address in @iph and the
185                          * addresses in home address option for final source.
186                          * See 11.3.2 of RFC 3775 for details.
187                          */
188                         if (opt[off] == IPV6_TLV_HAO) {
189                                 struct in6_addr final_addr;
190                                 struct ipv6_destopt_hao *hao;
191 
192                                 hao = (struct ipv6_destopt_hao *)&opt[off];
193                                 if (hao->length != sizeof(hao->addr)) {
194                                         net_warn_ratelimited("destopt hao: invalid header length: %u\n",
195                                                              hao->length);
196                                         goto bad;
197                                 }
198                                 final_addr = hao->addr;
199                                 hao->addr = iph->saddr;
200                                 iph->saddr = final_addr;
201                         }
202                         break;
203                 }
204 
205                 off += optlen;
206                 len -= optlen;
207         }
208         /* Note: ok if len == 0 */
209 bad:
210         return;
211 }
212 #else
213 static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt) {}
214 #endif
215 
216 /**
217  *      ipv6_rearrange_rthdr - rearrange IPv6 routing header
218  *      @iph: IPv6 header
219  *      @rthdr: routing header
220  *
221  *      Rearrange the destination address in @iph and the addresses in @rthdr
222  *      so that they appear in the order they will at the final destination.
223  *      See Appendix A2 of RFC 2402 for details.
224  */
225 static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr)
226 {
227         int segments, segments_left;
228         struct in6_addr *addrs;
229         struct in6_addr final_addr;
230 
231         segments_left = rthdr->segments_left;
232         if (segments_left == 0)
233                 return;
234         rthdr->segments_left = 0;
235 
236         /* The value of rthdr->hdrlen has been verified either by the system
237          * call if it is locally generated, or by ipv6_rthdr_rcv() for incoming
238          * packets.  So we can assume that it is even and that segments is
239          * greater than or equal to segments_left.
240          *
241          * For the same reason we can assume that this option is of type 0.
242          */
243         segments = rthdr->hdrlen >> 1;
244 
245         addrs = ((struct rt0_hdr *)rthdr)->addr;
246         final_addr = addrs[segments - 1];
247 
248         addrs += segments - segments_left;
249         memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs));
250 
251         addrs[0] = iph->daddr;
252         iph->daddr = final_addr;
253 }
254 
255 static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len, int dir)
256 {
257         union {
258                 struct ipv6hdr *iph;
259                 struct ipv6_opt_hdr *opth;
260                 struct ipv6_rt_hdr *rth;
261                 char *raw;
262         } exthdr = { .iph = iph };
263         char *end = exthdr.raw + len;
264         int nexthdr = iph->nexthdr;
265 
266         exthdr.iph++;
267 
268         while (exthdr.raw < end) {
269                 switch (nexthdr) {
270                 case NEXTHDR_DEST:
271                         if (dir == XFRM_POLICY_OUT)
272                                 ipv6_rearrange_destopt(iph, exthdr.opth);
273                 case NEXTHDR_HOP:
274                         if (!zero_out_mutable_opts(exthdr.opth)) {
275                                 LIMIT_NETDEBUG(
276                                         KERN_WARNING "overrun %sopts\n",
277                                         nexthdr == NEXTHDR_HOP ?
278                                                 "hop" : "dest");
279                                 return -EINVAL;
280                         }
281                         break;
282 
283                 case NEXTHDR_ROUTING:
284                         ipv6_rearrange_rthdr(iph, exthdr.rth);
285                         break;
286 
287                 default :
288                         return 0;
289                 }
290 
291                 nexthdr = exthdr.opth->nexthdr;
292                 exthdr.raw += ipv6_optlen(exthdr.opth);
293         }
294 
295         return 0;
296 }
297 
298 static void ah6_output_done(struct crypto_async_request *base, int err)
299 {
300         int extlen;
301         u8 *iph_base;
302         u8 *icv;
303         struct sk_buff *skb = base->data;
304         struct xfrm_state *x = skb_dst(skb)->xfrm;
305         struct ah_data *ahp = x->data;
306         struct ipv6hdr *top_iph = ipv6_hdr(skb);
307         struct ip_auth_hdr *ah = ip_auth_hdr(skb);
308         struct tmp_ext *iph_ext;
309 
310         extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
311         if (extlen)
312                 extlen += sizeof(*iph_ext);
313 
314         iph_base = AH_SKB_CB(skb)->tmp;
315         iph_ext = ah_tmp_ext(iph_base);
316         icv = ah_tmp_icv(ahp->ahash, iph_ext, extlen);
317 
318         memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
319         memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
320 
321         if (extlen) {
322 #if IS_ENABLED(CONFIG_IPV6_MIP6)
323                 memcpy(&top_iph->saddr, iph_ext, extlen);
324 #else
325                 memcpy(&top_iph->daddr, iph_ext, extlen);
326 #endif
327         }
328 
329         kfree(AH_SKB_CB(skb)->tmp);
330         xfrm_output_resume(skb, err);
331 }
332 
333 static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
334 {
335         int err;
336         int nfrags;
337         int extlen;
338         u8 *iph_base;
339         u8 *icv;
340         u8 nexthdr;
341         struct sk_buff *trailer;
342         struct crypto_ahash *ahash;
343         struct ahash_request *req;
344         struct scatterlist *sg;
345         struct ipv6hdr *top_iph;
346         struct ip_auth_hdr *ah;
347         struct ah_data *ahp;
348         struct tmp_ext *iph_ext;
349 
350         ahp = x->data;
351         ahash = ahp->ahash;
352 
353         if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
354                 goto out;
355         nfrags = err;
356 
357         skb_push(skb, -skb_network_offset(skb));
358         extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
359         if (extlen)
360                 extlen += sizeof(*iph_ext);
361 
362         err = -ENOMEM;
363         iph_base = ah_alloc_tmp(ahash, nfrags, IPV6HDR_BASELEN + extlen);
364         if (!iph_base)
365                 goto out;
366 
367         iph_ext = ah_tmp_ext(iph_base);
368         icv = ah_tmp_icv(ahash, iph_ext, extlen);
369         req = ah_tmp_req(ahash, icv);
370         sg = ah_req_sg(ahash, req);
371 
372         ah = ip_auth_hdr(skb);
373         memset(ah->auth_data, 0, ahp->icv_trunc_len);
374 
375         top_iph = ipv6_hdr(skb);
376         top_iph->payload_len = htons(skb->len - sizeof(*top_iph));
377 
378         nexthdr = *skb_mac_header(skb);
379         *skb_mac_header(skb) = IPPROTO_AH;
380 
381         /* When there are no extension headers, we only need to save the first
382          * 8 bytes of the base IP header.
383          */
384         memcpy(iph_base, top_iph, IPV6HDR_BASELEN);
385 
386         if (extlen) {
387 #if IS_ENABLED(CONFIG_IPV6_MIP6)
388                 memcpy(iph_ext, &top_iph->saddr, extlen);
389 #else
390                 memcpy(iph_ext, &top_iph->daddr, extlen);
391 #endif
392                 err = ipv6_clear_mutable_options(top_iph,
393                                                  extlen - sizeof(*iph_ext) +
394                                                  sizeof(*top_iph),
395                                                  XFRM_POLICY_OUT);
396                 if (err)
397                         goto out_free;
398         }
399 
400         ah->nexthdr = nexthdr;
401 
402         top_iph->priority    = 0;
403         top_iph->flow_lbl[0] = 0;
404         top_iph->flow_lbl[1] = 0;
405         top_iph->flow_lbl[2] = 0;
406         top_iph->hop_limit   = 0;
407 
408         ah->hdrlen  = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
409 
410         ah->reserved = 0;
411         ah->spi = x->id.spi;
412         ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
413 
414         sg_init_table(sg, nfrags);
415         skb_to_sgvec(skb, sg, 0, skb->len);
416 
417         ahash_request_set_crypt(req, sg, icv, skb->len);
418         ahash_request_set_callback(req, 0, ah6_output_done, skb);
419 
420         AH_SKB_CB(skb)->tmp = iph_base;
421 
422         err = crypto_ahash_digest(req);
423         if (err) {
424                 if (err == -EINPROGRESS)
425                         goto out;
426 
427                 if (err == -EBUSY)
428                         err = NET_XMIT_DROP;
429                 goto out_free;
430         }
431 
432         memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
433         memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
434 
435         if (extlen) {
436 #if IS_ENABLED(CONFIG_IPV6_MIP6)
437                 memcpy(&top_iph->saddr, iph_ext, extlen);
438 #else
439                 memcpy(&top_iph->daddr, iph_ext, extlen);
440 #endif
441         }
442 
443 out_free:
444         kfree(iph_base);
445 out:
446         return err;
447 }
448 
449 static void ah6_input_done(struct crypto_async_request *base, int err)
450 {
451         u8 *auth_data;
452         u8 *icv;
453         u8 *work_iph;
454         struct sk_buff *skb = base->data;
455         struct xfrm_state *x = xfrm_input_state(skb);
456         struct ah_data *ahp = x->data;
457         struct ip_auth_hdr *ah = ip_auth_hdr(skb);
458         int hdr_len = skb_network_header_len(skb);
459         int ah_hlen = (ah->hdrlen + 2) << 2;
460 
461         work_iph = AH_SKB_CB(skb)->tmp;
462         auth_data = ah_tmp_auth(work_iph, hdr_len);
463         icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);
464 
465         err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
466         if (err)
467                 goto out;
468 
469         err = ah->nexthdr;
470 
471         skb->network_header += ah_hlen;
472         memcpy(skb_network_header(skb), work_iph, hdr_len);
473         __skb_pull(skb, ah_hlen + hdr_len);
474         if (x->props.mode == XFRM_MODE_TUNNEL)
475                 skb_reset_transport_header(skb);
476         else
477                 skb_set_transport_header(skb, -hdr_len);
478 out:
479         kfree(AH_SKB_CB(skb)->tmp);
480         xfrm_input_resume(skb, err);
481 }
482 
483 
484 
485 static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
486 {
487         /*
488          * Before process AH
489          * [IPv6][Ext1][Ext2][AH][Dest][Payload]
490          * |<-------------->| hdr_len
491          *
492          * To erase AH:
493          * Keeping copy of cleared headers. After AH processing,
494          * Moving the pointer of skb->network_header by using skb_pull as long
495          * as AH header length. Then copy back the copy as long as hdr_len
496          * If destination header following AH exists, copy it into after [Ext2].
497          *
498          * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
499          * There is offset of AH before IPv6 header after the process.
500          */
501 
502         u8 *auth_data;
503         u8 *icv;
504         u8 *work_iph;
505         struct sk_buff *trailer;
506         struct crypto_ahash *ahash;
507         struct ahash_request *req;
508         struct scatterlist *sg;
509         struct ip_auth_hdr *ah;
510         struct ipv6hdr *ip6h;
511         struct ah_data *ahp;
512         u16 hdr_len;
513         u16 ah_hlen;
514         int nexthdr;
515         int nfrags;
516         int err = -ENOMEM;
517 
518         if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
519                 goto out;
520 
521         /* We are going to _remove_ AH header to keep sockets happy,
522          * so... Later this can change. */
523         if (skb_unclone(skb, GFP_ATOMIC))
524                 goto out;
525 
526         skb->ip_summed = CHECKSUM_NONE;
527 
528         hdr_len = skb_network_header_len(skb);
529         ah = (struct ip_auth_hdr *)skb->data;
530         ahp = x->data;
531         ahash = ahp->ahash;
532 
533         nexthdr = ah->nexthdr;
534         ah_hlen = (ah->hdrlen + 2) << 2;
535 
536         if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
537             ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
538                 goto out;
539 
540         if (!pskb_may_pull(skb, ah_hlen))
541                 goto out;
542 
543 
544         if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
545                 goto out;
546         nfrags = err;
547 
548         ah = (struct ip_auth_hdr *)skb->data;
549         ip6h = ipv6_hdr(skb);
550 
551         skb_push(skb, hdr_len);
552 
553         work_iph = ah_alloc_tmp(ahash, nfrags, hdr_len + ahp->icv_trunc_len);
554         if (!work_iph)
555                 goto out;
556 
557         auth_data = ah_tmp_auth(work_iph, hdr_len);
558         icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len);
559         req = ah_tmp_req(ahash, icv);
560         sg = ah_req_sg(ahash, req);
561 
562         memcpy(work_iph, ip6h, hdr_len);
563         memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
564         memset(ah->auth_data, 0, ahp->icv_trunc_len);
565 
566         if (ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN))
567                 goto out_free;
568 
569         ip6h->priority    = 0;
570         ip6h->flow_lbl[0] = 0;
571         ip6h->flow_lbl[1] = 0;
572         ip6h->flow_lbl[2] = 0;
573         ip6h->hop_limit   = 0;
574 
575         sg_init_table(sg, nfrags);
576         skb_to_sgvec(skb, sg, 0, skb->len);
577 
578         ahash_request_set_crypt(req, sg, icv, skb->len);
579         ahash_request_set_callback(req, 0, ah6_input_done, skb);
580 
581         AH_SKB_CB(skb)->tmp = work_iph;
582 
583         err = crypto_ahash_digest(req);
584         if (err) {
585                 if (err == -EINPROGRESS)
586                         goto out;
587 
588                 goto out_free;
589         }
590 
591         err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
592         if (err)
593                 goto out_free;
594 
595         skb->network_header += ah_hlen;
596         memcpy(skb_network_header(skb), work_iph, hdr_len);
597         __skb_pull(skb, ah_hlen + hdr_len);
598 
599         if (x->props.mode == XFRM_MODE_TUNNEL)
600                 skb_reset_transport_header(skb);
601         else
602                 skb_set_transport_header(skb, -hdr_len);
603 
604         err = nexthdr;
605 
606 out_free:
607         kfree(work_iph);
608 out:
609         return err;
610 }
611 
612 static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
613                     u8 type, u8 code, int offset, __be32 info)
614 {
615         struct net *net = dev_net(skb->dev);
616         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
617         struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+offset);
618         struct xfrm_state *x;
619 
620         if (type != ICMPV6_PKT_TOOBIG &&
621             type != NDISC_REDIRECT)
622                 return;
623 
624         x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
625         if (!x)
626                 return;
627 
628         if (type == NDISC_REDIRECT)
629                 ip6_redirect(skb, net, skb->dev->ifindex, 0);
630         else
631                 ip6_update_pmtu(skb, net, info, 0, 0);
632         xfrm_state_put(x);
633 }
634 
635 static int ah6_init_state(struct xfrm_state *x)
636 {
637         struct ah_data *ahp = NULL;
638         struct xfrm_algo_desc *aalg_desc;
639         struct crypto_ahash *ahash;
640 
641         if (!x->aalg)
642                 goto error;
643 
644         if (x->encap)
645                 goto error;
646 
647         ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
648         if (ahp == NULL)
649                 return -ENOMEM;
650 
651         ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
652         if (IS_ERR(ahash))
653                 goto error;
654 
655         ahp->ahash = ahash;
656         if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
657                                (x->aalg->alg_key_len + 7) / 8))
658                 goto error;
659 
660         /*
661          * Lookup the algorithm description maintained by xfrm_algo,
662          * verify crypto transform properties, and store information
663          * we need for AH processing.  This lookup cannot fail here
664          * after a successful crypto_alloc_hash().
665          */
666         aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
667         BUG_ON(!aalg_desc);
668 
669         if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
670             crypto_ahash_digestsize(ahash)) {
671                 pr_info("AH: %s digestsize %u != %hu\n",
672                         x->aalg->alg_name, crypto_ahash_digestsize(ahash),
673                         aalg_desc->uinfo.auth.icv_fullbits/8);
674                 goto error;
675         }
676 
677         ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
678         ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
679 
680         BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
681 
682         x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
683                                           ahp->icv_trunc_len);
684         switch (x->props.mode) {
685         case XFRM_MODE_BEET:
686         case XFRM_MODE_TRANSPORT:
687                 break;
688         case XFRM_MODE_TUNNEL:
689                 x->props.header_len += sizeof(struct ipv6hdr);
690                 break;
691         default:
692                 goto error;
693         }
694         x->data = ahp;
695 
696         return 0;
697 
698 error:
699         if (ahp) {
700                 crypto_free_ahash(ahp->ahash);
701                 kfree(ahp);
702         }
703         return -EINVAL;
704 }
705 
706 static void ah6_destroy(struct xfrm_state *x)
707 {
708         struct ah_data *ahp = x->data;
709 
710         if (!ahp)
711                 return;
712 
713         crypto_free_ahash(ahp->ahash);
714         kfree(ahp);
715 }
716 
717 static const struct xfrm_type ah6_type =
718 {
719         .description    = "AH6",
720         .owner          = THIS_MODULE,
721         .proto          = IPPROTO_AH,
722         .flags          = XFRM_TYPE_REPLAY_PROT,
723         .init_state     = ah6_init_state,
724         .destructor     = ah6_destroy,
725         .input          = ah6_input,
726         .output         = ah6_output,
727         .hdr_offset     = xfrm6_find_1stfragopt,
728 };
729 
730 static const struct inet6_protocol ah6_protocol = {
731         .handler        =       xfrm6_rcv,
732         .err_handler    =       ah6_err,
733         .flags          =       INET6_PROTO_NOPOLICY,
734 };
735 
736 static int __init ah6_init(void)
737 {
738         if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
739                 pr_info("%s: can't add xfrm type\n", __func__);
740                 return -EAGAIN;
741         }
742 
743         if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) {
744                 pr_info("%s: can't add protocol\n", __func__);
745                 xfrm_unregister_type(&ah6_type, AF_INET6);
746                 return -EAGAIN;
747         }
748 
749         return 0;
750 }
751 
752 static void __exit ah6_fini(void)
753 {
754         if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0)
755                 pr_info("%s: can't remove protocol\n", __func__);
756 
757         if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
758                 pr_info("%s: can't remove xfrm type\n", __func__);
759 
760 }
761 
762 module_init(ah6_init);
763 module_exit(ah6_fini);
764 
765 MODULE_LICENSE("GPL");
766 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_AH);
767 

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