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/esp.c
24 */
25
26#define pr_fmt(fmt) "IPv6: " fmt
27
28#include <crypto/aead.h>
29#include <crypto/authenc.h>
30#include <linux/err.h>
31#include <linux/module.h>
32#include <net/ip.h>
33#include <net/xfrm.h>
34#include <net/esp.h>
35#include <linux/scatterlist.h>
36#include <linux/kernel.h>
37#include <linux/pfkeyv2.h>
38#include <linux/random.h>
39#include <linux/slab.h>
40#include <linux/spinlock.h>
41#include <net/ip6_route.h>
42#include <net/icmp.h>
43#include <net/ipv6.h>
44#include <net/protocol.h>
45#include <linux/icmpv6.h>
46
47struct esp_skb_cb {
48	struct xfrm_skb_cb xfrm;
49	void *tmp;
50};
51
52#define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0]))
53
54static u32 esp6_get_mtu(struct xfrm_state *x, int mtu);
55
56/*
57 * Allocate an AEAD request structure with extra space for SG and IV.
58 *
59 * For alignment considerations the upper 32 bits of the sequence number are
60 * placed at the front, if present. Followed by the IV, the request and finally
61 * the SG list.
62 *
63 * TODO: Use spare space in skb for this where possible.
64 */
65static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags, int seqihlen)
66{
67	unsigned int len;
68
69	len = seqihlen;
70
71	len += crypto_aead_ivsize(aead);
72
73	if (len) {
74		len += crypto_aead_alignmask(aead) &
75		       ~(crypto_tfm_ctx_alignment() - 1);
76		len = ALIGN(len, crypto_tfm_ctx_alignment());
77	}
78
79	len += sizeof(struct aead_givcrypt_request) + crypto_aead_reqsize(aead);
80	len = ALIGN(len, __alignof__(struct scatterlist));
81
82	len += sizeof(struct scatterlist) * nfrags;
83
84	return kmalloc(len, GFP_ATOMIC);
85}
86
87static inline __be32 *esp_tmp_seqhi(void *tmp)
88{
89	return PTR_ALIGN((__be32 *)tmp, __alignof__(__be32));
90}
91
92static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp, int seqhilen)
93{
94	return crypto_aead_ivsize(aead) ?
95	       PTR_ALIGN((u8 *)tmp + seqhilen,
96			 crypto_aead_alignmask(aead) + 1) : tmp + seqhilen;
97}
98
99static inline struct aead_givcrypt_request *esp_tmp_givreq(
100	struct crypto_aead *aead, u8 *iv)
101{
102	struct aead_givcrypt_request *req;
103
104	req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
105				crypto_tfm_ctx_alignment());
106	aead_givcrypt_set_tfm(req, aead);
107	return req;
108}
109
110static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv)
111{
112	struct aead_request *req;
113
114	req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
115				crypto_tfm_ctx_alignment());
116	aead_request_set_tfm(req, aead);
117	return req;
118}
119
120static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead,
121					     struct aead_request *req)
122{
123	return (void *)ALIGN((unsigned long)(req + 1) +
124			     crypto_aead_reqsize(aead),
125			     __alignof__(struct scatterlist));
126}
127
128static inline struct scatterlist *esp_givreq_sg(
129	struct crypto_aead *aead, struct aead_givcrypt_request *req)
130{
131	return (void *)ALIGN((unsigned long)(req + 1) +
132			     crypto_aead_reqsize(aead),
133			     __alignof__(struct scatterlist));
134}
135
136static void esp_output_done(struct crypto_async_request *base, int err)
137{
138	struct sk_buff *skb = base->data;
139
140	kfree(ESP_SKB_CB(skb)->tmp);
141	xfrm_output_resume(skb, err);
142}
143
144static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
145{
146	int err;
147	struct ip_esp_hdr *esph;
148	struct crypto_aead *aead;
149	struct aead_givcrypt_request *req;
150	struct scatterlist *sg;
151	struct scatterlist *asg;
152	struct sk_buff *trailer;
153	void *tmp;
154	int blksize;
155	int clen;
156	int alen;
157	int plen;
158	int tfclen;
159	int nfrags;
160	int assoclen;
161	int sglists;
162	int seqhilen;
163	u8 *iv;
164	u8 *tail;
165	__be32 *seqhi;
166
167	/* skb is pure payload to encrypt */
168	aead = x->data;
169	alen = crypto_aead_authsize(aead);
170
171	tfclen = 0;
172	if (x->tfcpad) {
173		struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb);
174		u32 padto;
175
176		padto = min(x->tfcpad, esp6_get_mtu(x, dst->child_mtu_cached));
177		if (skb->len < padto)
178			tfclen = padto - skb->len;
179	}
180	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
181	clen = ALIGN(skb->len + 2 + tfclen, blksize);
182	plen = clen - skb->len - tfclen;
183
184	err = skb_cow_data(skb, tfclen + plen + alen, &trailer);
185	if (err < 0)
186		goto error;
187	nfrags = err;
188
189	assoclen = sizeof(*esph);
190	sglists = 1;
191	seqhilen = 0;
192
193	if (x->props.flags & XFRM_STATE_ESN) {
194		sglists += 2;
195		seqhilen += sizeof(__be32);
196		assoclen += seqhilen;
197	}
198
199	tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen);
200	if (!tmp) {
201		err = -ENOMEM;
202		goto error;
203	}
204
205	seqhi = esp_tmp_seqhi(tmp);
206	iv = esp_tmp_iv(aead, tmp, seqhilen);
207	req = esp_tmp_givreq(aead, iv);
208	asg = esp_givreq_sg(aead, req);
209	sg = asg + sglists;
210
211	/* Fill padding... */
212	tail = skb_tail_pointer(trailer);
213	if (tfclen) {
214		memset(tail, 0, tfclen);
215		tail += tfclen;
216	}
217	do {
218		int i;
219		for (i = 0; i < plen - 2; i++)
220			tail[i] = i + 1;
221	} while (0);
222	tail[plen - 2] = plen - 2;
223	tail[plen - 1] = *skb_mac_header(skb);
224	pskb_put(skb, trailer, clen - skb->len + alen);
225
226	skb_push(skb, -skb_network_offset(skb));
227	esph = ip_esp_hdr(skb);
228	*skb_mac_header(skb) = IPPROTO_ESP;
229
230	esph->spi = x->id.spi;
231	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
232
233	sg_init_table(sg, nfrags);
234	skb_to_sgvec(skb, sg,
235		     esph->enc_data + crypto_aead_ivsize(aead) - skb->data,
236		     clen + alen);
237
238	if ((x->props.flags & XFRM_STATE_ESN)) {
239		sg_init_table(asg, 3);
240		sg_set_buf(asg, &esph->spi, sizeof(__be32));
241		*seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
242		sg_set_buf(asg + 1, seqhi, seqhilen);
243		sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32));
244	} else
245		sg_init_one(asg, esph, sizeof(*esph));
246
247	aead_givcrypt_set_callback(req, 0, esp_output_done, skb);
248	aead_givcrypt_set_crypt(req, sg, sg, clen, iv);
249	aead_givcrypt_set_assoc(req, asg, assoclen);
250	aead_givcrypt_set_giv(req, esph->enc_data,
251			      XFRM_SKB_CB(skb)->seq.output.low);
252
253	ESP_SKB_CB(skb)->tmp = tmp;
254	err = crypto_aead_givencrypt(req);
255	if (err == -EINPROGRESS)
256		goto error;
257
258	if (err == -EBUSY)
259		err = NET_XMIT_DROP;
260
261	kfree(tmp);
262
263error:
264	return err;
265}
266
267static int esp_input_done2(struct sk_buff *skb, int err)
268{
269	struct xfrm_state *x = xfrm_input_state(skb);
270	struct crypto_aead *aead = x->data;
271	int alen = crypto_aead_authsize(aead);
272	int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
273	int elen = skb->len - hlen;
274	int hdr_len = skb_network_header_len(skb);
275	int padlen;
276	u8 nexthdr[2];
277
278	kfree(ESP_SKB_CB(skb)->tmp);
279
280	if (unlikely(err))
281		goto out;
282
283	if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2))
284		BUG();
285
286	err = -EINVAL;
287	padlen = nexthdr[0];
288	if (padlen + 2 + alen >= elen) {
289		LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage "
290			       "padlen=%d, elen=%d\n", padlen + 2, elen - alen);
291		goto out;
292	}
293
294	/* ... check padding bits here. Silly. :-) */
295
296	pskb_trim(skb, skb->len - alen - padlen - 2);
297	__skb_pull(skb, hlen);
298	if (x->props.mode == XFRM_MODE_TUNNEL)
299		skb_reset_transport_header(skb);
300	else
301		skb_set_transport_header(skb, -hdr_len);
302
303	err = nexthdr[1];
304
305	/* RFC4303: Drop dummy packets without any error */
306	if (err == IPPROTO_NONE)
307		err = -EINVAL;
308
309out:
310	return err;
311}
312
313static void esp_input_done(struct crypto_async_request *base, int err)
314{
315	struct sk_buff *skb = base->data;
316
317	xfrm_input_resume(skb, esp_input_done2(skb, err));
318}
319
320static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
321{
322	struct ip_esp_hdr *esph;
323	struct crypto_aead *aead = x->data;
324	struct aead_request *req;
325	struct sk_buff *trailer;
326	int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead);
327	int nfrags;
328	int assoclen;
329	int sglists;
330	int seqhilen;
331	int ret = 0;
332	void *tmp;
333	__be32 *seqhi;
334	u8 *iv;
335	struct scatterlist *sg;
336	struct scatterlist *asg;
337
338	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead))) {
339		ret = -EINVAL;
340		goto out;
341	}
342
343	if (elen <= 0) {
344		ret = -EINVAL;
345		goto out;
346	}
347
348	if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
349		ret = -EINVAL;
350		goto out;
351	}
352
353	ret = -ENOMEM;
354
355	assoclen = sizeof(*esph);
356	sglists = 1;
357	seqhilen = 0;
358
359	if (x->props.flags & XFRM_STATE_ESN) {
360		sglists += 2;
361		seqhilen += sizeof(__be32);
362		assoclen += seqhilen;
363	}
364
365	tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen);
366	if (!tmp)
367		goto out;
368
369	ESP_SKB_CB(skb)->tmp = tmp;
370	seqhi = esp_tmp_seqhi(tmp);
371	iv = esp_tmp_iv(aead, tmp, seqhilen);
372	req = esp_tmp_req(aead, iv);
373	asg = esp_req_sg(aead, req);
374	sg = asg + sglists;
375
376	skb->ip_summed = CHECKSUM_NONE;
377
378	esph = (struct ip_esp_hdr *)skb->data;
379
380	/* Get ivec. This can be wrong, check against another impls. */
381	iv = esph->enc_data;
382
383	sg_init_table(sg, nfrags);
384	skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen);
385
386	if ((x->props.flags & XFRM_STATE_ESN)) {
387		sg_init_table(asg, 3);
388		sg_set_buf(asg, &esph->spi, sizeof(__be32));
389		*seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
390		sg_set_buf(asg + 1, seqhi, seqhilen);
391		sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32));
392	} else
393		sg_init_one(asg, esph, sizeof(*esph));
394
395	aead_request_set_callback(req, 0, esp_input_done, skb);
396	aead_request_set_crypt(req, sg, sg, elen, iv);
397	aead_request_set_assoc(req, asg, assoclen);
398
399	ret = crypto_aead_decrypt(req);
400	if (ret == -EINPROGRESS)
401		goto out;
402
403	ret = esp_input_done2(skb, ret);
404
405out:
406	return ret;
407}
408
409static u32 esp6_get_mtu(struct xfrm_state *x, int mtu)
410{
411	struct crypto_aead *aead = x->data;
412	u32 blksize = ALIGN(crypto_aead_blocksize(aead), 4);
413	unsigned int net_adj;
414
415	if (x->props.mode != XFRM_MODE_TUNNEL)
416		net_adj = sizeof(struct ipv6hdr);
417	else
418		net_adj = 0;
419
420	return ((mtu - x->props.header_len - crypto_aead_authsize(aead) -
421		 net_adj) & ~(blksize - 1)) + net_adj - 2;
422}
423
424static int esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
425		    u8 type, u8 code, int offset, __be32 info)
426{
427	struct net *net = dev_net(skb->dev);
428	const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data;
429	struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset);
430	struct xfrm_state *x;
431
432	if (type != ICMPV6_PKT_TOOBIG &&
433	    type != NDISC_REDIRECT)
434		return 0;
435
436	x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
437			      esph->spi, IPPROTO_ESP, AF_INET6);
438	if (!x)
439		return 0;
440
441	if (type == NDISC_REDIRECT)
442		ip6_redirect(skb, net, skb->dev->ifindex, 0);
443	else
444		ip6_update_pmtu(skb, net, info, 0, 0, INVALID_UID);
445	xfrm_state_put(x);
446
447	return 0;
448}
449
450static void esp6_destroy(struct xfrm_state *x)
451{
452	struct crypto_aead *aead = x->data;
453
454	if (!aead)
455		return;
456
457	crypto_free_aead(aead);
458}
459
460static int esp_init_aead(struct xfrm_state *x)
461{
462	struct crypto_aead *aead;
463	int err;
464
465	aead = crypto_alloc_aead(x->aead->alg_name, 0, 0);
466	err = PTR_ERR(aead);
467	if (IS_ERR(aead))
468		goto error;
469
470	x->data = aead;
471
472	err = crypto_aead_setkey(aead, x->aead->alg_key,
473				 (x->aead->alg_key_len + 7) / 8);
474	if (err)
475		goto error;
476
477	err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8);
478	if (err)
479		goto error;
480
481error:
482	return err;
483}
484
485static int esp_init_authenc(struct xfrm_state *x)
486{
487	struct crypto_aead *aead;
488	struct crypto_authenc_key_param *param;
489	struct rtattr *rta;
490	char *key;
491	char *p;
492	char authenc_name[CRYPTO_MAX_ALG_NAME];
493	unsigned int keylen;
494	int err;
495
496	err = -EINVAL;
497	if (x->ealg == NULL)
498		goto error;
499
500	err = -ENAMETOOLONG;
501
502	if ((x->props.flags & XFRM_STATE_ESN)) {
503		if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
504			     "authencesn(%s,%s)",
505			     x->aalg ? x->aalg->alg_name : "digest_null",
506			     x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
507			goto error;
508	} else {
509		if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
510			     "authenc(%s,%s)",
511			     x->aalg ? x->aalg->alg_name : "digest_null",
512			     x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
513			goto error;
514	}
515
516	aead = crypto_alloc_aead(authenc_name, 0, 0);
517	err = PTR_ERR(aead);
518	if (IS_ERR(aead))
519		goto error;
520
521	x->data = aead;
522
523	keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) +
524		 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param));
525	err = -ENOMEM;
526	key = kmalloc(keylen, GFP_KERNEL);
527	if (!key)
528		goto error;
529
530	p = key;
531	rta = (void *)p;
532	rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM;
533	rta->rta_len = RTA_LENGTH(sizeof(*param));
534	param = RTA_DATA(rta);
535	p += RTA_SPACE(sizeof(*param));
536
537	if (x->aalg) {
538		struct xfrm_algo_desc *aalg_desc;
539
540		memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8);
541		p += (x->aalg->alg_key_len + 7) / 8;
542
543		aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
544		BUG_ON(!aalg_desc);
545
546		err = -EINVAL;
547		if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
548		    crypto_aead_authsize(aead)) {
549			NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
550				 x->aalg->alg_name,
551				 crypto_aead_authsize(aead),
552				 aalg_desc->uinfo.auth.icv_fullbits/8);
553			goto free_key;
554		}
555
556		err = crypto_aead_setauthsize(
557			aead, x->aalg->alg_trunc_len / 8);
558		if (err)
559			goto free_key;
560	}
561
562	param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8);
563	memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8);
564
565	err = crypto_aead_setkey(aead, key, keylen);
566
567free_key:
568	kfree(key);
569
570error:
571	return err;
572}
573
574static int esp6_init_state(struct xfrm_state *x)
575{
576	struct crypto_aead *aead;
577	u32 align;
578	int err;
579
580	if (x->encap)
581		return -EINVAL;
582
583	x->data = NULL;
584
585	if (x->aead)
586		err = esp_init_aead(x);
587	else
588		err = esp_init_authenc(x);
589
590	if (err)
591		goto error;
592
593	aead = x->data;
594
595	x->props.header_len = sizeof(struct ip_esp_hdr) +
596			      crypto_aead_ivsize(aead);
597	switch (x->props.mode) {
598	case XFRM_MODE_BEET:
599		if (x->sel.family != AF_INET6)
600			x->props.header_len += IPV4_BEET_PHMAXLEN +
601					       (sizeof(struct ipv6hdr) - sizeof(struct iphdr));
602		break;
603	case XFRM_MODE_TRANSPORT:
604		break;
605	case XFRM_MODE_TUNNEL:
606		x->props.header_len += sizeof(struct ipv6hdr);
607		break;
608	default:
609		goto error;
610	}
611
612	align = ALIGN(crypto_aead_blocksize(aead), 4);
613	x->props.trailer_len = align + 1 + crypto_aead_authsize(aead);
614
615error:
616	return err;
617}
618
619static int esp6_rcv_cb(struct sk_buff *skb, int err)
620{
621	return 0;
622}
623
624static const struct xfrm_type esp6_type = {
625	.description	= "ESP6",
626	.owner		= THIS_MODULE,
627	.proto		= IPPROTO_ESP,
628	.flags		= XFRM_TYPE_REPLAY_PROT,
629	.init_state	= esp6_init_state,
630	.destructor	= esp6_destroy,
631	.get_mtu	= esp6_get_mtu,
632	.input		= esp6_input,
633	.output		= esp6_output,
634	.hdr_offset	= xfrm6_find_1stfragopt,
635};
636
637static struct xfrm6_protocol esp6_protocol = {
638	.handler	=	xfrm6_rcv,
639	.cb_handler	=	esp6_rcv_cb,
640	.err_handler	=	esp6_err,
641	.priority	=	0,
642};
643
644static int __init esp6_init(void)
645{
646	if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
647		pr_info("%s: can't add xfrm type\n", __func__);
648		return -EAGAIN;
649	}
650	if (xfrm6_protocol_register(&esp6_protocol, IPPROTO_ESP) < 0) {
651		pr_info("%s: can't add protocol\n", __func__);
652		xfrm_unregister_type(&esp6_type, AF_INET6);
653		return -EAGAIN;
654	}
655
656	return 0;
657}
658
659static void __exit esp6_fini(void)
660{
661	if (xfrm6_protocol_deregister(&esp6_protocol, IPPROTO_ESP) < 0)
662		pr_info("%s: can't remove protocol\n", __func__);
663	if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
664		pr_info("%s: can't remove xfrm type\n", __func__);
665}
666
667module_init(esp6_init);
668module_exit(esp6_fini);
669
670MODULE_LICENSE("GPL");
671MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP);
672