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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/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);
817 

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