summaryrefslogtreecommitdiff
path: root/net/ipv6/ah6.c
blob: 25e1172fd1c3c260c44f52caded07198729ff533 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C)2002 USAGI/WIDE Project
 *
 * Authors
 *
 *	Mitsuru KANDA @USAGI       : IPv6 Support
 *	Kazunori MIYAZAWA @USAGI   :
 *	Kunihiro Ishiguro <kunihiro@ipinfusion.com>
 *
 *	This file is derived from net/ipv4/ah.c.
 */

#define pr_fmt(fmt) "IPv6: " fmt

#include <crypto/algapi.h>
#include <crypto/hash.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <net/ip.h>
#include <net/ah.h>
#include <linux/crypto.h>
#include <linux/pfkeyv2.h>
#include <linux/string.h>
#include <linux/scatterlist.h>
#include <net/ip6_route.h>
#include <net/icmp.h>
#include <net/ipv6.h>
#include <net/protocol.h>
#include <net/xfrm.h>

#define IPV6HDR_BASELEN 8

struct tmp_ext {
#if IS_ENABLED(CONFIG_IPV6_MIP6)
		struct in6_addr saddr;
#endif
		struct in6_addr daddr;
		char hdrs[0];
};

struct ah_skb_cb {
	struct xfrm_skb_cb xfrm;
	void *tmp;
};

#define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0]))

static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags,
			  unsigned int size)
{
	unsigned int len;

	len = size + crypto_ahash_digestsize(ahash) +
	      (crypto_ahash_alignmask(ahash) &
	       ~(crypto_tfm_ctx_alignment() - 1));

	len = ALIGN(len, crypto_tfm_ctx_alignment());

	len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash);
	len = ALIGN(len, __alignof__(struct scatterlist));

	len += sizeof(struct scatterlist) * nfrags;

	return kmalloc(len, GFP_ATOMIC);
}

static inline struct tmp_ext *ah_tmp_ext(void *base)
{
	return base + IPV6HDR_BASELEN;
}

static inline u8 *ah_tmp_auth(u8 *tmp, unsigned int offset)
{
	return tmp + offset;
}

static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp,
			     unsigned int offset)
{
	return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1);
}

static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash,
					       u8 *icv)
{
	struct ahash_request *req;

	req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash),
				crypto_tfm_ctx_alignment());

	ahash_request_set_tfm(req, ahash);

	return req;
}

static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash,
					     struct ahash_request *req)
{
	return (void *)ALIGN((unsigned long)(req + 1) +
			     crypto_ahash_reqsize(ahash),
			     __alignof__(struct scatterlist));
}

static bool zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr)
{
	u8 *opt = (u8 *)opthdr;
	int len = ipv6_optlen(opthdr);
	int off = 0;
	int optlen = 0;

	off += 2;
	len -= 2;

	while (len > 0) {

		switch (opt[off]) {

		case IPV6_TLV_PAD1:
			optlen = 1;
			break;
		default:
			if (len < 2)
				goto bad;
			optlen = opt[off+1]+2;
			if (len < optlen)
				goto bad;
			if (opt[off] & 0x20)
				memset(&opt[off+2], 0, opt[off+1]);
			break;
		}

		off += optlen;
		len -= optlen;
	}
	if (len == 0)
		return true;

bad:
	return false;
}

#if IS_ENABLED(CONFIG_IPV6_MIP6)
/**
 *	ipv6_rearrange_destopt - rearrange IPv6 destination options header
 *	@iph: IPv6 header
 *	@destopt: destionation options header
 */
static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt)
{
	u8 *opt = (u8 *)destopt;
	int len = ipv6_optlen(destopt);
	int off = 0;
	int optlen = 0;

	off += 2;
	len -= 2;

	while (len > 0) {

		switch (opt[off]) {

		case IPV6_TLV_PAD1:
			optlen = 1;
			break;
		default:
			if (len < 2)
				goto bad;
			optlen = opt[off+1]+2;
			if (len < optlen)
				goto bad;

			/* Rearrange the source address in @iph and the
			 * addresses in home address option for final source.
			 * See 11.3.2 of RFC 3775 for details.
			 */
			if (opt[off] == IPV6_TLV_HAO) {
				struct in6_addr final_addr;
				struct ipv6_destopt_hao *hao;

				hao = (struct ipv6_destopt_hao *)&opt[off];
				if (hao->length != sizeof(hao->addr)) {
					net_warn_ratelimited("destopt hao: invalid header length: %u\n",
							     hao->length);
					goto bad;
				}
				final_addr = hao->addr;
				hao->addr = iph->saddr;
				iph->saddr = final_addr;
			}
			break;
		}

		off += optlen;
		len -= optlen;
	}
	/* Note: ok if len == 0 */
bad:
	return;
}
#else
static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt) {}
#endif

/**
 *	ipv6_rearrange_rthdr - rearrange IPv6 routing header
 *	@iph: IPv6 header
 *	@rthdr: routing header
 *
 *	Rearrange the destination address in @iph and the addresses in @rthdr
 *	so that they appear in the order they will at the final destination.
 *	See Appendix A2 of RFC 2402 for details.
 */
static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr)
{
	int segments, segments_left;
	struct in6_addr *addrs;
	struct in6_addr final_addr;

	segments_left = rthdr->segments_left;
	if (segments_left == 0)
		return;
	rthdr->segments_left = 0;

	/* The value of rthdr->hdrlen has been verified either by the system
	 * call if it is locally generated, or by ipv6_rthdr_rcv() for incoming
	 * packets.  So we can assume that it is even and that segments is
	 * greater than or equal to segments_left.
	 *
	 * For the same reason we can assume that this option is of type 0.
	 */
	segments = rthdr->hdrlen >> 1;

	addrs = ((struct rt0_hdr *)rthdr)->addr;
	final_addr = addrs[segments - 1];

	addrs += segments - segments_left;
	memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs));

	addrs[0] = iph->daddr;
	iph->daddr = final_addr;
}

static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len, int dir)
{
	union {
		struct ipv6hdr *iph;
		struct ipv6_opt_hdr *opth;
		struct ipv6_rt_hdr *rth;
		char *raw;
	} exthdr = { .iph = iph };
	char *end = exthdr.raw + len;
	int nexthdr = iph->nexthdr;

	exthdr.iph++;

	while (exthdr.raw < end) {
		switch (nexthdr) {
		case NEXTHDR_DEST:
			if (dir == XFRM_POLICY_OUT)
				ipv6_rearrange_destopt(iph, exthdr.opth);
			/* fall through */
		case NEXTHDR_HOP:
			if (!zero_out_mutable_opts(exthdr.opth)) {
				net_dbg_ratelimited("overrun %sopts\n",
						    nexthdr == NEXTHDR_HOP ?
						    "hop" : "dest");
				return -EINVAL;
			}
			break;

		case NEXTHDR_ROUTING:
			ipv6_rearrange_rthdr(iph, exthdr.rth);
			break;

		default:
			return 0;
		}

		nexthdr = exthdr.opth->nexthdr;
		exthdr.raw += ipv6_optlen(exthdr.opth);
	}

	return 0;
}

static void ah6_output_done(struct crypto_async_request *base, int err)
{
	int extlen;
	u8 *iph_base;
	u8 *icv;
	struct sk_buff *skb = base->data;
	struct xfrm_state *x = skb_dst(skb)->xfrm;
	struct ah_data *ahp = x->data;
	struct ipv6hdr *top_iph = ipv6_hdr(skb);
	struct ip_auth_hdr *ah = ip_auth_hdr(skb);
	struct tmp_ext *iph_ext;

	extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
	if (extlen)
		extlen += sizeof(*iph_ext);

	iph_base = AH_SKB_CB(skb)->tmp;
	iph_ext = ah_tmp_ext(iph_base);
	icv = ah_tmp_icv(ahp->ahash, iph_ext, extlen);

	memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
	memcpy(top_iph, iph_base, IPV6HDR_BASELEN);

	if (extlen) {
#if IS_ENABLED(CONFIG_IPV6_MIP6)
		memcpy(&top_iph->saddr, iph_ext, extlen);
#else
		memcpy(&top_iph->daddr, iph_ext, extlen);
#endif
	}

	kfree(AH_SKB_CB(skb)->tmp);
	xfrm_output_resume(skb, err);
}

static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
{
	int err;
	int nfrags;
	int extlen;
	u8 *iph_base;
	u8 *icv;
	u8 nexthdr;
	struct sk_buff *trailer;
	struct crypto_ahash *ahash;
	struct ahash_request *req;
	struct scatterlist *sg;
	struct ipv6hdr *top_iph;
	struct ip_auth_hdr *ah;
	struct ah_data *ahp;
	struct tmp_ext *iph_ext;
	int seqhi_len = 0;
	__be32 *seqhi;
	int sglists = 0;
	struct scatterlist *seqhisg;

	ahp = x->data;
	ahash = ahp->ahash;

	err = skb_cow_data(skb, 0, &trailer);
	if (err < 0)
		goto out;
	nfrags = err;

	skb_push(skb, -skb_network_offset(skb));
	extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
	if (extlen)
		extlen += sizeof(*iph_ext);

	if (x->props.flags & XFRM_STATE_ESN) {
		sglists = 1;
		seqhi_len = sizeof(*seqhi);
	}
	err = -ENOMEM;
	iph_base = ah_alloc_tmp(ahash, nfrags + sglists, IPV6HDR_BASELEN +
				extlen + seqhi_len);
	if (!iph_base)
		goto out;

	iph_ext = ah_tmp_ext(iph_base);
	seqhi = (__be32 *)((char *)iph_ext + extlen);
	icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
	req = ah_tmp_req(ahash, icv);
	sg = ah_req_sg(ahash, req);
	seqhisg = sg + nfrags;

	ah = ip_auth_hdr(skb);
	memset(ah->auth_data, 0, ahp->icv_trunc_len);

	top_iph = ipv6_hdr(skb);
	top_iph->payload_len = htons(skb->len - sizeof(*top_iph));

	nexthdr = *skb_mac_header(skb);
	*skb_mac_header(skb) = IPPROTO_AH;

	/* When there are no extension headers, we only need to save the first
	 * 8 bytes of the base IP header.
	 */
	memcpy(iph_base, top_iph, IPV6HDR_BASELEN);

	if (extlen) {
#if IS_ENABLED(CONFIG_IPV6_MIP6)
		memcpy(iph_ext, &top_iph->saddr, extlen);
#else
		memcpy(iph_ext, &top_iph->daddr, extlen);
#endif
		err = ipv6_clear_mutable_options(top_iph,
						 extlen - sizeof(*iph_ext) +
						 sizeof(*top_iph),
						 XFRM_POLICY_OUT);
		if (err)
			goto out_free;
	}

	ah->nexthdr = nexthdr;

	top_iph->priority    = 0;
	top_iph->flow_lbl[0] = 0;
	top_iph->flow_lbl[1] = 0;
	top_iph->flow_lbl[2] = 0;
	top_iph->hop_limit   = 0;

	ah->hdrlen  = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;

	ah->reserved = 0;
	ah->spi = x->id.spi;
	ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);

	sg_init_table(sg, nfrags + sglists);
	err = skb_to_sgvec_nomark(skb, sg, 0, skb->len);
	if (unlikely(err < 0))
		goto out_free;

	if (x->props.flags & XFRM_STATE_ESN) {
		/* Attach seqhi sg right after packet payload */
		*seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
		sg_set_buf(seqhisg, seqhi, seqhi_len);
	}
	ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
	ahash_request_set_callback(req, 0, ah6_output_done, skb);

	AH_SKB_CB(skb)->tmp = iph_base;

	err = crypto_ahash_digest(req);
	if (err) {
		if (err == -EINPROGRESS)
			goto out;

		if (err == -ENOSPC)
			err = NET_XMIT_DROP;
		goto out_free;
	}

	memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
	memcpy(top_iph, iph_base, IPV6HDR_BASELEN);

	if (extlen) {
#if IS_ENABLED(CONFIG_IPV6_MIP6)
		memcpy(&top_iph->saddr, iph_ext, extlen);
#else
		memcpy(&top_iph->daddr, iph_ext, extlen);
#endif
	}

out_free:
	kfree(iph_base);
out:
	return err;
}

static void ah6_input_done(struct crypto_async_request *base, int err)
{
	u8 *auth_data;
	u8 *icv;
	u8 *work_iph;
	struct sk_buff *skb = base->data;
	struct xfrm_state *x = xfrm_input_state(skb);
	struct ah_data *ahp = x->data;
	struct ip_auth_hdr *ah = ip_auth_hdr(skb);
	int hdr_len = skb_network_header_len(skb);
	int ah_hlen = (ah->hdrlen + 2) << 2;

	if (err)
		goto out;

	work_iph = AH_SKB_CB(skb)->tmp;
	auth_data = ah_tmp_auth(work_iph, hdr_len);
	icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);

	err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
	if (err)
		goto out;

	err = ah->nexthdr;

	skb->network_header += ah_hlen;
	memcpy(skb_network_header(skb), work_iph, hdr_len);
	__skb_pull(skb, ah_hlen + hdr_len);
	if (x->props.mode == XFRM_MODE_TUNNEL)
		skb_reset_transport_header(skb);
	else
		skb_set_transport_header(skb, -hdr_len);
out:
	kfree(AH_SKB_CB(skb)->tmp);
	xfrm_input_resume(skb, err);
}



static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
{
	/*
	 * Before process AH
	 * [IPv6][Ext1][Ext2][AH][Dest][Payload]
	 * |<-------------->| hdr_len
	 *
	 * To erase AH:
	 * Keeping copy of cleared headers. After AH processing,
	 * Moving the pointer of skb->network_header by using skb_pull as long
	 * as AH header length. Then copy back the copy as long as hdr_len
	 * If destination header following AH exists, copy it into after [Ext2].
	 *
	 * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
	 * There is offset of AH before IPv6 header after the process.
	 */

	u8 *auth_data;
	u8 *icv;
	u8 *work_iph;
	struct sk_buff *trailer;
	struct crypto_ahash *ahash;
	struct ahash_request *req;
	struct scatterlist *sg;
	struct ip_auth_hdr *ah;
	struct ipv6hdr *ip6h;
	struct ah_data *ahp;
	u16 hdr_len;
	u16 ah_hlen;
	int nexthdr;
	int nfrags;
	int err = -ENOMEM;
	int seqhi_len = 0;
	__be32 *seqhi;
	int sglists = 0;
	struct scatterlist *seqhisg;

	if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
		goto out;

	/* We are going to _remove_ AH header to keep sockets happy,
	 * so... Later this can change. */
	if (skb_unclone(skb, GFP_ATOMIC))
		goto out;

	skb->ip_summed = CHECKSUM_NONE;

	hdr_len = skb_network_header_len(skb);
	ah = (struct ip_auth_hdr *)skb->data;
	ahp = x->data;
	ahash = ahp->ahash;

	nexthdr = ah->nexthdr;
	ah_hlen = (ah->hdrlen + 2) << 2;

	if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
	    ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
		goto out;

	if (!pskb_may_pull(skb, ah_hlen))
		goto out;

	err = skb_cow_data(skb, 0, &trailer);
	if (err < 0)
		goto out;
	nfrags = err;

	ah = (struct ip_auth_hdr *)skb->data;
	ip6h = ipv6_hdr(skb);

	skb_push(skb, hdr_len);

	if (x->props.flags & XFRM_STATE_ESN) {
		sglists = 1;
		seqhi_len = sizeof(*seqhi);
	}

	work_iph = ah_alloc_tmp(ahash, nfrags + sglists, hdr_len +
				ahp->icv_trunc_len + seqhi_len);
	if (!work_iph) {
		err = -ENOMEM;
		goto out;
	}

	auth_data = ah_tmp_auth((u8 *)work_iph, hdr_len);
	seqhi = (__be32 *)(auth_data + ahp->icv_trunc_len);
	icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
	req = ah_tmp_req(ahash, icv);
	sg = ah_req_sg(ahash, req);
	seqhisg = sg + nfrags;

	memcpy(work_iph, ip6h, hdr_len);
	memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
	memset(ah->auth_data, 0, ahp->icv_trunc_len);

	if (ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN))
		goto out_free;

	ip6h->priority    = 0;
	ip6h->flow_lbl[0] = 0;
	ip6h->flow_lbl[1] = 0;
	ip6h->flow_lbl[2] = 0;
	ip6h->hop_limit   = 0;

	sg_init_table(sg, nfrags + sglists);
	err = skb_to_sgvec_nomark(skb, sg, 0, skb->len);
	if (unlikely(err < 0))
		goto out_free;

	if (x->props.flags & XFRM_STATE_ESN) {
		/* Attach seqhi sg right after packet payload */
		*seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
		sg_set_buf(seqhisg, seqhi, seqhi_len);
	}

	ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
	ahash_request_set_callback(req, 0, ah6_input_done, skb);

	AH_SKB_CB(skb)->tmp = work_iph;

	err = crypto_ahash_digest(req);
	if (err) {
		if (err == -EINPROGRESS)
			goto out;

		goto out_free;
	}

	err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
	if (err)
		goto out_free;

	skb->network_header += ah_hlen;
	memcpy(skb_network_header(skb), work_iph, hdr_len);
	__skb_pull(skb, ah_hlen + hdr_len);

	if (x->props.mode == XFRM_MODE_TUNNEL)
		skb_reset_transport_header(skb);
	else
		skb_set_transport_header(skb, -hdr_len);

	err = nexthdr;

out_free:
	kfree(work_iph);
out:
	return err;
}

static int ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
		   u8 type, u8 code, int offset, __be32 info)
{
	struct net *net = dev_net(skb->dev);
	struct ipv6hdr *iph = (struct ipv6hdr *)skb->data;
	struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+offset);
	struct xfrm_state *x;

	if (type != ICMPV6_PKT_TOOBIG &&
	    type != NDISC_REDIRECT)
		return 0;

	x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
	if (!x)
		return 0;

	if (type == NDISC_REDIRECT)
		ip6_redirect(skb, net, skb->dev->ifindex, 0,
			     sock_net_uid(net, NULL));
	else
		ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));
	xfrm_state_put(x);

	return 0;
}

static int ah6_init_state(struct xfrm_state *x)
{
	struct ah_data *ahp = NULL;
	struct xfrm_algo_desc *aalg_desc;
	struct crypto_ahash *ahash;

	if (!x->aalg)
		goto error;

	if (x->encap)
		goto error;

	ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
	if (!ahp)
		return -ENOMEM;

	ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
	if (IS_ERR(ahash))
		goto error;

	ahp->ahash = ahash;
	if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
			       (x->aalg->alg_key_len + 7) / 8))
		goto error;

	/*
	 * Lookup the algorithm description maintained by xfrm_algo,
	 * verify crypto transform properties, and store information
	 * we need for AH processing.  This lookup cannot fail here
	 * after a successful crypto_alloc_hash().
	 */
	aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
	BUG_ON(!aalg_desc);

	if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
	    crypto_ahash_digestsize(ahash)) {
		pr_info("AH: %s digestsize %u != %hu\n",
			x->aalg->alg_name, crypto_ahash_digestsize(ahash),
			aalg_desc->uinfo.auth.icv_fullbits/8);
		goto error;
	}

	ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
	ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;

	x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
					  ahp->icv_trunc_len);
	switch (x->props.mode) {
	case XFRM_MODE_BEET:
	case XFRM_MODE_TRANSPORT:
		break;
	case XFRM_MODE_TUNNEL:
		x->props.header_len += sizeof(struct ipv6hdr);
		break;
	default:
		goto error;
	}
	x->data = ahp;

	return 0;

error:
	if (ahp) {
		crypto_free_ahash(ahp->ahash);
		kfree(ahp);
	}
	return -EINVAL;
}

static void ah6_destroy(struct xfrm_state *x)
{
	struct ah_data *ahp = x->data;

	if (!ahp)
		return;

	crypto_free_ahash(ahp->ahash);
	kfree(ahp);
}

static int ah6_rcv_cb(struct sk_buff *skb, int err)
{
	return 0;
}

static const struct xfrm_type ah6_type = {
	.description	= "AH6",
	.owner		= THIS_MODULE,
	.proto		= IPPROTO_AH,
	.flags		= XFRM_TYPE_REPLAY_PROT,
	.init_state	= ah6_init_state,
	.destructor	= ah6_destroy,
	.input		= ah6_input,
	.output		= ah6_output,
	.hdr_offset	= xfrm6_find_1stfragopt,
};

static struct xfrm6_protocol ah6_protocol = {
	.handler	=	xfrm6_rcv,
	.cb_handler	=	ah6_rcv_cb,
	.err_handler	=	ah6_err,
	.priority	=	0,
};

static int __init ah6_init(void)
{
	if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
		pr_info("%s: can't add xfrm type\n", __func__);
		return -EAGAIN;
	}

	if (xfrm6_protocol_register(&ah6_protocol, IPPROTO_AH) < 0) {
		pr_info("%s: can't add protocol\n", __func__);
		xfrm_unregister_type(&ah6_type, AF_INET6);
		return -EAGAIN;
	}

	return 0;
}

static void __exit ah6_fini(void)
{
	if (xfrm6_protocol_deregister(&ah6_protocol, IPPROTO_AH) < 0)
		pr_info("%s: can't remove protocol\n", __func__);

	xfrm_unregister_type(&ah6_type, AF_INET6);
}

module_init(ah6_init);
module_exit(ah6_fini);

MODULE_LICENSE("GPL");
MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_AH);