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TOMOYO Linux Cross Reference
Linux/net/ipv6/ah6.c

Version: ~ [ linux-5.7 ] ~ [ linux-5.6.15 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.43 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.125 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.182 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.225 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.225 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.84 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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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 
 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                                 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 
299 static 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 IS_ENABLED(CONFIG_IPV6_MIP6)
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 
334 static 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 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);
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 IS_ENABLED(CONFIG_IPV6_MIP6)
438                 memcpy(&top_iph->saddr, iph_ext, extlen);
439 #else
440                 memcpy(&top_iph->daddr, iph_ext, extlen);
441 #endif
442         }
443 
444 out_free:
445         kfree(iph_base);
446 out:
447         return err;
448 }
449 
450 static 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         if (x->props.mode == XFRM_MODE_TUNNEL)
476                 skb_reset_transport_header(skb);
477         else
478                 skb_set_transport_header(skb, -hdr_len);
479 out:
480         kfree(AH_SKB_CB(skb)->tmp);
481         xfrm_input_resume(skb, err);
482 }
483 
484 
485 
486 static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
487 {
488         /*
489          * Before process AH
490          * [IPv6][Ext1][Ext2][AH][Dest][Payload]
491          * |<-------------->| hdr_len
492          *
493          * To erase AH:
494          * Keeping copy of cleared headers. After AH processing,
495          * Moving the pointer of skb->network_header by using skb_pull as long
496          * as AH header length. Then copy back the copy as long as hdr_len
497          * If destination header following AH exists, copy it into after [Ext2].
498          *
499          * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
500          * There is offset of AH before IPv6 header after the process.
501          */
502 
503         u8 *auth_data;
504         u8 *icv;
505         u8 *work_iph;
506         struct sk_buff *trailer;
507         struct crypto_ahash *ahash;
508         struct ahash_request *req;
509         struct scatterlist *sg;
510         struct ip_auth_hdr *ah;
511         struct ipv6hdr *ip6h;
512         struct ah_data *ahp;
513         u16 hdr_len;
514         u16 ah_hlen;
515         int nexthdr;
516         int nfrags;
517         int err = -ENOMEM;
518 
519         if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
520                 goto out;
521 
522         /* We are going to _remove_ AH header to keep sockets happy,
523          * so... Later this can change. */
524         if (skb_unclone(skb, GFP_ATOMIC))
525                 goto out;
526 
527         skb->ip_summed = CHECKSUM_NONE;
528 
529         hdr_len = skb_network_header_len(skb);
530         ah = (struct ip_auth_hdr *)skb->data;
531         ahp = x->data;
532         ahash = ahp->ahash;
533 
534         nexthdr = ah->nexthdr;
535         ah_hlen = (ah->hdrlen + 2) << 2;
536 
537         if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
538             ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
539                 goto out;
540 
541         if (!pskb_may_pull(skb, ah_hlen))
542                 goto out;
543 
544 
545         if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
546                 goto out;
547         nfrags = err;
548 
549         ah = (struct ip_auth_hdr *)skb->data;
550         ip6h = ipv6_hdr(skb);
551 
552         skb_push(skb, hdr_len);
553 
554         work_iph = ah_alloc_tmp(ahash, nfrags, hdr_len + ahp->icv_trunc_len);
555         if (!work_iph)
556                 goto out;
557 
558         auth_data = ah_tmp_auth(work_iph, hdr_len);
559         icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len);
560         req = ah_tmp_req(ahash, icv);
561         sg = ah_req_sg(ahash, req);
562 
563         memcpy(work_iph, ip6h, hdr_len);
564         memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
565         memset(ah->auth_data, 0, ahp->icv_trunc_len);
566 
567         if (ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN))
568                 goto out_free;
569 
570         ip6h->priority    = 0;
571         ip6h->flow_lbl[0] = 0;
572         ip6h->flow_lbl[1] = 0;
573         ip6h->flow_lbl[2] = 0;
574         ip6h->hop_limit   = 0;
575 
576         sg_init_table(sg, nfrags);
577         skb_to_sgvec(skb, sg, 0, skb->len);
578 
579         ahash_request_set_crypt(req, sg, icv, skb->len);
580         ahash_request_set_callback(req, 0, ah6_input_done, skb);
581 
582         AH_SKB_CB(skb)->tmp = work_iph;
583 
584         err = crypto_ahash_digest(req);
585         if (err) {
586                 if (err == -EINPROGRESS)
587                         goto out;
588 
589                 goto out_free;
590         }
591 
592         err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
593         if (err)
594                 goto out_free;
595 
596         skb->network_header += ah_hlen;
597         memcpy(skb_network_header(skb), work_iph, hdr_len);
598         __skb_pull(skb, ah_hlen + hdr_len);
599 
600         if (x->props.mode == XFRM_MODE_TUNNEL)
601                 skb_reset_transport_header(skb);
602         else
603                 skb_set_transport_header(skb, -hdr_len);
604 
605         err = nexthdr;
606 
607 out_free:
608         kfree(work_iph);
609 out:
610         return err;
611 }
612 
613 static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
614                     u8 type, u8 code, int offset, __be32 info)
615 {
616         struct net *net = dev_net(skb->dev);
617         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
618         struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+offset);
619         struct xfrm_state *x;
620 
621         if (type != ICMPV6_PKT_TOOBIG &&
622             type != NDISC_REDIRECT)
623                 return;
624 
625         x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
626         if (!x)
627                 return;
628 
629         if (type == NDISC_REDIRECT)
630                 ip6_redirect(skb, net, skb->dev->ifindex, 0);
631         else
632                 ip6_update_pmtu(skb, net, info, 0, 0);
633         xfrm_state_put(x);
634 }
635 
636 static int ah6_init_state(struct xfrm_state *x)
637 {
638         struct ah_data *ahp = NULL;
639         struct xfrm_algo_desc *aalg_desc;
640         struct crypto_ahash *ahash;
641 
642         if (!x->aalg)
643                 goto error;
644 
645         if (x->encap)
646                 goto error;
647 
648         ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
649         if (ahp == NULL)
650                 return -ENOMEM;
651 
652         ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
653         if (IS_ERR(ahash))
654                 goto error;
655 
656         ahp->ahash = ahash;
657         if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
658                                (x->aalg->alg_key_len + 7) / 8))
659                 goto error;
660 
661         /*
662          * Lookup the algorithm description maintained by xfrm_algo,
663          * verify crypto transform properties, and store information
664          * we need for AH processing.  This lookup cannot fail here
665          * after a successful crypto_alloc_hash().
666          */
667         aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
668         BUG_ON(!aalg_desc);
669 
670         if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
671             crypto_ahash_digestsize(ahash)) {
672                 pr_info("AH: %s digestsize %u != %hu\n",
673                         x->aalg->alg_name, crypto_ahash_digestsize(ahash),
674                         aalg_desc->uinfo.auth.icv_fullbits/8);
675                 goto error;
676         }
677 
678         ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
679         ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
680 
681         BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
682 
683         x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
684                                           ahp->icv_trunc_len);
685         switch (x->props.mode) {
686         case XFRM_MODE_BEET:
687         case XFRM_MODE_TRANSPORT:
688                 break;
689         case XFRM_MODE_TUNNEL:
690                 x->props.header_len += sizeof(struct ipv6hdr);
691                 break;
692         default:
693                 goto error;
694         }
695         x->data = ahp;
696 
697         return 0;
698 
699 error:
700         if (ahp) {
701                 crypto_free_ahash(ahp->ahash);
702                 kfree(ahp);
703         }
704         return -EINVAL;
705 }
706 
707 static void ah6_destroy(struct xfrm_state *x)
708 {
709         struct ah_data *ahp = x->data;
710 
711         if (!ahp)
712                 return;
713 
714         crypto_free_ahash(ahp->ahash);
715         kfree(ahp);
716 }
717 
718 static const struct xfrm_type ah6_type =
719 {
720         .description    = "AH6",
721         .owner          = THIS_MODULE,
722         .proto          = IPPROTO_AH,
723         .flags          = XFRM_TYPE_REPLAY_PROT,
724         .init_state     = ah6_init_state,
725         .destructor     = ah6_destroy,
726         .input          = ah6_input,
727         .output         = ah6_output,
728         .hdr_offset     = xfrm6_find_1stfragopt,
729 };
730 
731 static const struct inet6_protocol ah6_protocol = {
732         .handler        =       xfrm6_rcv,
733         .err_handler    =       ah6_err,
734         .flags          =       INET6_PROTO_NOPOLICY,
735 };
736 
737 static int __init ah6_init(void)
738 {
739         if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
740                 pr_info("%s: can't add xfrm type\n", __func__);
741                 return -EAGAIN;
742         }
743 
744         if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) {
745                 pr_info("%s: can't add protocol\n", __func__);
746                 xfrm_unregister_type(&ah6_type, AF_INET6);
747                 return -EAGAIN;
748         }
749 
750         return 0;
751 }
752 
753 static void __exit ah6_fini(void)
754 {
755         if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0)
756                 pr_info("%s: can't remove protocol\n", __func__);
757 
758         if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
759                 pr_info("%s: can't remove xfrm type\n", __func__);
760 
761 }
762 
763 module_init(ah6_init);
764 module_exit(ah6_fini);
765 
766 MODULE_LICENSE("GPL");
767 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_AH);
768 

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