xref: /openbmc/linux/net/ipv6/ah6.c (revision 6774def6)
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 	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 	if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
358 		goto out;
359 	nfrags = err;
360 
361 	skb_push(skb, -skb_network_offset(skb));
362 	extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
363 	if (extlen)
364 		extlen += sizeof(*iph_ext);
365 
366 	if (x->props.flags & XFRM_STATE_ESN) {
367 		sglists = 1;
368 		seqhi_len = sizeof(*seqhi);
369 	}
370 	err = -ENOMEM;
371 	iph_base = ah_alloc_tmp(ahash, nfrags + sglists, IPV6HDR_BASELEN +
372 				extlen + seqhi_len);
373 	if (!iph_base)
374 		goto out;
375 
376 	iph_ext = ah_tmp_ext(iph_base);
377 	seqhi = (__be32 *)((char *)iph_ext + extlen);
378 	icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
379 	req = ah_tmp_req(ahash, icv);
380 	sg = ah_req_sg(ahash, req);
381 	seqhisg = sg + nfrags;
382 
383 	ah = ip_auth_hdr(skb);
384 	memset(ah->auth_data, 0, ahp->icv_trunc_len);
385 
386 	top_iph = ipv6_hdr(skb);
387 	top_iph->payload_len = htons(skb->len - sizeof(*top_iph));
388 
389 	nexthdr = *skb_mac_header(skb);
390 	*skb_mac_header(skb) = IPPROTO_AH;
391 
392 	/* When there are no extension headers, we only need to save the first
393 	 * 8 bytes of the base IP header.
394 	 */
395 	memcpy(iph_base, top_iph, IPV6HDR_BASELEN);
396 
397 	if (extlen) {
398 #if IS_ENABLED(CONFIG_IPV6_MIP6)
399 		memcpy(iph_ext, &top_iph->saddr, extlen);
400 #else
401 		memcpy(iph_ext, &top_iph->daddr, extlen);
402 #endif
403 		err = ipv6_clear_mutable_options(top_iph,
404 						 extlen - sizeof(*iph_ext) +
405 						 sizeof(*top_iph),
406 						 XFRM_POLICY_OUT);
407 		if (err)
408 			goto out_free;
409 	}
410 
411 	ah->nexthdr = nexthdr;
412 
413 	top_iph->priority    = 0;
414 	top_iph->flow_lbl[0] = 0;
415 	top_iph->flow_lbl[1] = 0;
416 	top_iph->flow_lbl[2] = 0;
417 	top_iph->hop_limit   = 0;
418 
419 	ah->hdrlen  = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
420 
421 	ah->reserved = 0;
422 	ah->spi = x->id.spi;
423 	ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
424 
425 	sg_init_table(sg, nfrags + sglists);
426 	skb_to_sgvec_nomark(skb, sg, 0, skb->len);
427 
428 	if (x->props.flags & XFRM_STATE_ESN) {
429 		/* Attach seqhi sg right after packet payload */
430 		*seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
431 		sg_set_buf(seqhisg, seqhi, seqhi_len);
432 	}
433 	ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
434 	ahash_request_set_callback(req, 0, ah6_output_done, skb);
435 
436 	AH_SKB_CB(skb)->tmp = iph_base;
437 
438 	err = crypto_ahash_digest(req);
439 	if (err) {
440 		if (err == -EINPROGRESS)
441 			goto out;
442 
443 		if (err == -EBUSY)
444 			err = NET_XMIT_DROP;
445 		goto out_free;
446 	}
447 
448 	memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
449 	memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
450 
451 	if (extlen) {
452 #if IS_ENABLED(CONFIG_IPV6_MIP6)
453 		memcpy(&top_iph->saddr, iph_ext, extlen);
454 #else
455 		memcpy(&top_iph->daddr, iph_ext, extlen);
456 #endif
457 	}
458 
459 out_free:
460 	kfree(iph_base);
461 out:
462 	return err;
463 }
464 
465 static void ah6_input_done(struct crypto_async_request *base, int err)
466 {
467 	u8 *auth_data;
468 	u8 *icv;
469 	u8 *work_iph;
470 	struct sk_buff *skb = base->data;
471 	struct xfrm_state *x = xfrm_input_state(skb);
472 	struct ah_data *ahp = x->data;
473 	struct ip_auth_hdr *ah = ip_auth_hdr(skb);
474 	int hdr_len = skb_network_header_len(skb);
475 	int ah_hlen = (ah->hdrlen + 2) << 2;
476 
477 	work_iph = AH_SKB_CB(skb)->tmp;
478 	auth_data = ah_tmp_auth(work_iph, hdr_len);
479 	icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);
480 
481 	err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
482 	if (err)
483 		goto out;
484 
485 	err = ah->nexthdr;
486 
487 	skb->network_header += ah_hlen;
488 	memcpy(skb_network_header(skb), work_iph, hdr_len);
489 	__skb_pull(skb, ah_hlen + hdr_len);
490 	if (x->props.mode == XFRM_MODE_TUNNEL)
491 		skb_reset_transport_header(skb);
492 	else
493 		skb_set_transport_header(skb, -hdr_len);
494 out:
495 	kfree(AH_SKB_CB(skb)->tmp);
496 	xfrm_input_resume(skb, err);
497 }
498 
499 
500 
501 static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
502 {
503 	/*
504 	 * Before process AH
505 	 * [IPv6][Ext1][Ext2][AH][Dest][Payload]
506 	 * |<-------------->| hdr_len
507 	 *
508 	 * To erase AH:
509 	 * Keeping copy of cleared headers. After AH processing,
510 	 * Moving the pointer of skb->network_header by using skb_pull as long
511 	 * as AH header length. Then copy back the copy as long as hdr_len
512 	 * If destination header following AH exists, copy it into after [Ext2].
513 	 *
514 	 * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
515 	 * There is offset of AH before IPv6 header after the process.
516 	 */
517 
518 	u8 *auth_data;
519 	u8 *icv;
520 	u8 *work_iph;
521 	struct sk_buff *trailer;
522 	struct crypto_ahash *ahash;
523 	struct ahash_request *req;
524 	struct scatterlist *sg;
525 	struct ip_auth_hdr *ah;
526 	struct ipv6hdr *ip6h;
527 	struct ah_data *ahp;
528 	u16 hdr_len;
529 	u16 ah_hlen;
530 	int nexthdr;
531 	int nfrags;
532 	int err = -ENOMEM;
533 	int seqhi_len = 0;
534 	__be32 *seqhi;
535 	int sglists = 0;
536 	struct scatterlist *seqhisg;
537 
538 	if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
539 		goto out;
540 
541 	/* We are going to _remove_ AH header to keep sockets happy,
542 	 * so... Later this can change. */
543 	if (skb_unclone(skb, GFP_ATOMIC))
544 		goto out;
545 
546 	skb->ip_summed = CHECKSUM_NONE;
547 
548 	hdr_len = skb_network_header_len(skb);
549 	ah = (struct ip_auth_hdr *)skb->data;
550 	ahp = x->data;
551 	ahash = ahp->ahash;
552 
553 	nexthdr = ah->nexthdr;
554 	ah_hlen = (ah->hdrlen + 2) << 2;
555 
556 	if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
557 	    ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
558 		goto out;
559 
560 	if (!pskb_may_pull(skb, ah_hlen))
561 		goto out;
562 
563 
564 	if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
565 		goto out;
566 	nfrags = err;
567 
568 	ah = (struct ip_auth_hdr *)skb->data;
569 	ip6h = ipv6_hdr(skb);
570 
571 	skb_push(skb, hdr_len);
572 
573 	if (x->props.flags & XFRM_STATE_ESN) {
574 		sglists = 1;
575 		seqhi_len = sizeof(*seqhi);
576 	}
577 
578 	work_iph = ah_alloc_tmp(ahash, nfrags + sglists, hdr_len +
579 				ahp->icv_trunc_len + seqhi_len);
580 	if (!work_iph)
581 		goto out;
582 
583 	auth_data = ah_tmp_auth((u8 *)work_iph, hdr_len);
584 	seqhi = (__be32 *)(auth_data + ahp->icv_trunc_len);
585 	icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
586 	req = ah_tmp_req(ahash, icv);
587 	sg = ah_req_sg(ahash, req);
588 	seqhisg = sg + nfrags;
589 
590 	memcpy(work_iph, ip6h, hdr_len);
591 	memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
592 	memset(ah->auth_data, 0, ahp->icv_trunc_len);
593 
594 	if (ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN))
595 		goto out_free;
596 
597 	ip6h->priority    = 0;
598 	ip6h->flow_lbl[0] = 0;
599 	ip6h->flow_lbl[1] = 0;
600 	ip6h->flow_lbl[2] = 0;
601 	ip6h->hop_limit   = 0;
602 
603 	sg_init_table(sg, nfrags + sglists);
604 	skb_to_sgvec_nomark(skb, sg, 0, skb->len);
605 
606 	if (x->props.flags & XFRM_STATE_ESN) {
607 		/* Attach seqhi sg right after packet payload */
608 		*seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
609 		sg_set_buf(seqhisg, seqhi, seqhi_len);
610 	}
611 
612 	ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
613 	ahash_request_set_callback(req, 0, ah6_input_done, skb);
614 
615 	AH_SKB_CB(skb)->tmp = work_iph;
616 
617 	err = crypto_ahash_digest(req);
618 	if (err) {
619 		if (err == -EINPROGRESS)
620 			goto out;
621 
622 		goto out_free;
623 	}
624 
625 	err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
626 	if (err)
627 		goto out_free;
628 
629 	skb->network_header += ah_hlen;
630 	memcpy(skb_network_header(skb), work_iph, hdr_len);
631 	__skb_pull(skb, ah_hlen + hdr_len);
632 
633 	if (x->props.mode == XFRM_MODE_TUNNEL)
634 		skb_reset_transport_header(skb);
635 	else
636 		skb_set_transport_header(skb, -hdr_len);
637 
638 	err = nexthdr;
639 
640 out_free:
641 	kfree(work_iph);
642 out:
643 	return err;
644 }
645 
646 static int ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
647 		   u8 type, u8 code, int offset, __be32 info)
648 {
649 	struct net *net = dev_net(skb->dev);
650 	struct ipv6hdr *iph = (struct ipv6hdr *)skb->data;
651 	struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+offset);
652 	struct xfrm_state *x;
653 
654 	if (type != ICMPV6_PKT_TOOBIG &&
655 	    type != NDISC_REDIRECT)
656 		return 0;
657 
658 	x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
659 	if (!x)
660 		return 0;
661 
662 	if (type == NDISC_REDIRECT)
663 		ip6_redirect(skb, net, skb->dev->ifindex, 0);
664 	else
665 		ip6_update_pmtu(skb, net, info, 0, 0);
666 	xfrm_state_put(x);
667 
668 	return 0;
669 }
670 
671 static int ah6_init_state(struct xfrm_state *x)
672 {
673 	struct ah_data *ahp = NULL;
674 	struct xfrm_algo_desc *aalg_desc;
675 	struct crypto_ahash *ahash;
676 
677 	if (!x->aalg)
678 		goto error;
679 
680 	if (x->encap)
681 		goto error;
682 
683 	ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
684 	if (ahp == NULL)
685 		return -ENOMEM;
686 
687 	ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
688 	if (IS_ERR(ahash))
689 		goto error;
690 
691 	ahp->ahash = ahash;
692 	if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
693 			       (x->aalg->alg_key_len + 7) / 8))
694 		goto error;
695 
696 	/*
697 	 * Lookup the algorithm description maintained by xfrm_algo,
698 	 * verify crypto transform properties, and store information
699 	 * we need for AH processing.  This lookup cannot fail here
700 	 * after a successful crypto_alloc_hash().
701 	 */
702 	aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
703 	BUG_ON(!aalg_desc);
704 
705 	if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
706 	    crypto_ahash_digestsize(ahash)) {
707 		pr_info("AH: %s digestsize %u != %hu\n",
708 			x->aalg->alg_name, crypto_ahash_digestsize(ahash),
709 			aalg_desc->uinfo.auth.icv_fullbits/8);
710 		goto error;
711 	}
712 
713 	ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
714 	ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
715 
716 	x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
717 					  ahp->icv_trunc_len);
718 	switch (x->props.mode) {
719 	case XFRM_MODE_BEET:
720 	case XFRM_MODE_TRANSPORT:
721 		break;
722 	case XFRM_MODE_TUNNEL:
723 		x->props.header_len += sizeof(struct ipv6hdr);
724 		break;
725 	default:
726 		goto error;
727 	}
728 	x->data = ahp;
729 
730 	return 0;
731 
732 error:
733 	if (ahp) {
734 		crypto_free_ahash(ahp->ahash);
735 		kfree(ahp);
736 	}
737 	return -EINVAL;
738 }
739 
740 static void ah6_destroy(struct xfrm_state *x)
741 {
742 	struct ah_data *ahp = x->data;
743 
744 	if (!ahp)
745 		return;
746 
747 	crypto_free_ahash(ahp->ahash);
748 	kfree(ahp);
749 }
750 
751 static int ah6_rcv_cb(struct sk_buff *skb, int err)
752 {
753 	return 0;
754 }
755 
756 static const struct xfrm_type ah6_type = {
757 	.description	= "AH6",
758 	.owner		= THIS_MODULE,
759 	.proto		= IPPROTO_AH,
760 	.flags		= XFRM_TYPE_REPLAY_PROT,
761 	.init_state	= ah6_init_state,
762 	.destructor	= ah6_destroy,
763 	.input		= ah6_input,
764 	.output		= ah6_output,
765 	.hdr_offset	= xfrm6_find_1stfragopt,
766 };
767 
768 static struct xfrm6_protocol ah6_protocol = {
769 	.handler	=	xfrm6_rcv,
770 	.cb_handler	=	ah6_rcv_cb,
771 	.err_handler	=	ah6_err,
772 	.priority	=	0,
773 };
774 
775 static int __init ah6_init(void)
776 {
777 	if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
778 		pr_info("%s: can't add xfrm type\n", __func__);
779 		return -EAGAIN;
780 	}
781 
782 	if (xfrm6_protocol_register(&ah6_protocol, IPPROTO_AH) < 0) {
783 		pr_info("%s: can't add protocol\n", __func__);
784 		xfrm_unregister_type(&ah6_type, AF_INET6);
785 		return -EAGAIN;
786 	}
787 
788 	return 0;
789 }
790 
791 static void __exit ah6_fini(void)
792 {
793 	if (xfrm6_protocol_deregister(&ah6_protocol, IPPROTO_AH) < 0)
794 		pr_info("%s: can't remove protocol\n", __func__);
795 
796 	if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
797 		pr_info("%s: can't remove xfrm type\n", __func__);
798 
799 }
800 
801 module_init(ah6_init);
802 module_exit(ah6_fini);
803 
804 MODULE_LICENSE("GPL");
805 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_AH);
806