esp6.c revision 73d4f84fd001b0be67fea46e84b75e6a7a5da08e
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/esp.c
25 */
26
27#include <linux/config.h>
28#include <linux/module.h>
29#include <net/ip.h>
30#include <net/xfrm.h>
31#include <net/esp.h>
32#include <asm/scatterlist.h>
33#include <linux/crypto.h>
34#include <linux/kernel.h>
35#include <linux/pfkeyv2.h>
36#include <linux/random.h>
37#include <net/icmp.h>
38#include <net/ipv6.h>
39#include <linux/icmpv6.h>
40
41static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
42{
43	int err;
44	int hdr_len;
45	struct ipv6hdr *top_iph;
46	struct ipv6_esp_hdr *esph;
47	struct crypto_tfm *tfm;
48	struct esp_data *esp;
49	struct sk_buff *trailer;
50	int blksize;
51	int clen;
52	int alen;
53	int nfrags;
54
55	esp = x->data;
56	hdr_len = skb->h.raw - skb->data +
57		  sizeof(*esph) + esp->conf.ivlen;
58
59	/* Strip IP+ESP header. */
60	__skb_pull(skb, hdr_len);
61
62	/* Now skb is pure payload to encrypt */
63	err = -ENOMEM;
64
65	/* Round to block size */
66	clen = skb->len;
67
68	alen = esp->auth.icv_trunc_len;
69	tfm = esp->conf.tfm;
70	blksize = ALIGN(crypto_tfm_alg_blocksize(tfm), 4);
71	clen = ALIGN(clen + 2, blksize);
72	if (esp->conf.padlen)
73		clen = ALIGN(clen, esp->conf.padlen);
74
75	if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) {
76		goto error;
77	}
78
79	/* Fill padding... */
80	do {
81		int i;
82		for (i=0; i<clen-skb->len - 2; i++)
83			*(u8*)(trailer->tail + i) = i+1;
84	} while (0);
85	*(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2;
86	pskb_put(skb, trailer, clen - skb->len);
87
88	top_iph = (struct ipv6hdr *)__skb_push(skb, hdr_len);
89	esph = (struct ipv6_esp_hdr *)skb->h.raw;
90	top_iph->payload_len = htons(skb->len + alen - sizeof(*top_iph));
91	*(u8*)(trailer->tail - 1) = *skb->nh.raw;
92	*skb->nh.raw = IPPROTO_ESP;
93
94	esph->spi = x->id.spi;
95	esph->seq_no = htonl(++x->replay.oseq);
96
97	if (esp->conf.ivlen)
98		crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
99
100	do {
101		struct scatterlist *sg = &esp->sgbuf[0];
102
103		if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
104			sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
105			if (!sg)
106				goto error;
107		}
108		skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
109		crypto_cipher_encrypt(tfm, sg, sg, clen);
110		if (unlikely(sg != &esp->sgbuf[0]))
111			kfree(sg);
112	} while (0);
113
114	if (esp->conf.ivlen) {
115		memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
116		crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
117	}
118
119	if (esp->auth.icv_full_len) {
120		esp->auth.icv(esp, skb, (u8*)esph-skb->data,
121			sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen+clen, trailer->tail);
122		pskb_put(skb, trailer, alen);
123	}
124
125	err = 0;
126
127error:
128	return err;
129}
130
131static int esp6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
132{
133	struct ipv6hdr *iph;
134	struct ipv6_esp_hdr *esph;
135	struct esp_data *esp = x->data;
136	struct sk_buff *trailer;
137	int blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4);
138	int alen = esp->auth.icv_trunc_len;
139	int elen = skb->len - sizeof(struct ipv6_esp_hdr) - esp->conf.ivlen - alen;
140
141	int hdr_len = skb->h.raw - skb->nh.raw;
142	int nfrags;
143	unsigned char *tmp_hdr = NULL;
144	int ret = 0;
145
146	if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) {
147		ret = -EINVAL;
148		goto out_nofree;
149	}
150
151	if (elen <= 0 || (elen & (blksize-1))) {
152		ret = -EINVAL;
153		goto out_nofree;
154	}
155
156	tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
157	if (!tmp_hdr) {
158		ret = -ENOMEM;
159		goto out_nofree;
160	}
161	memcpy(tmp_hdr, skb->nh.raw, hdr_len);
162
163	/* If integrity check is required, do this. */
164        if (esp->auth.icv_full_len) {
165		u8 sum[esp->auth.icv_full_len];
166		u8 sum1[alen];
167
168		esp->auth.icv(esp, skb, 0, skb->len-alen, sum);
169
170		if (skb_copy_bits(skb, skb->len-alen, sum1, alen))
171			BUG();
172
173		if (unlikely(memcmp(sum, sum1, alen))) {
174			x->stats.integrity_failed++;
175			ret = -EINVAL;
176			goto out;
177		}
178	}
179
180	if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
181		ret = -EINVAL;
182		goto out;
183	}
184
185	skb->ip_summed = CHECKSUM_NONE;
186
187	esph = (struct ipv6_esp_hdr*)skb->data;
188	iph = skb->nh.ipv6h;
189
190	/* Get ivec. This can be wrong, check against another impls. */
191	if (esp->conf.ivlen)
192		crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm));
193
194        {
195		u8 nexthdr[2];
196		struct scatterlist *sg = &esp->sgbuf[0];
197		u8 padlen;
198
199		if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
200			sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
201			if (!sg) {
202				ret = -ENOMEM;
203				goto out;
204			}
205		}
206		skb_to_sgvec(skb, sg, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen, elen);
207		crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen);
208		if (unlikely(sg != &esp->sgbuf[0]))
209			kfree(sg);
210
211		if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
212			BUG();
213
214		padlen = nexthdr[0];
215		if (padlen+2 >= elen) {
216			LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen);
217			ret = -EINVAL;
218			goto out;
219		}
220		/* ... check padding bits here. Silly. :-) */
221
222		pskb_trim(skb, skb->len - alen - padlen - 2);
223		skb->h.raw = skb_pull(skb, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen);
224		skb->nh.raw += sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen;
225		memcpy(skb->nh.raw, tmp_hdr, hdr_len);
226		skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
227		ret = nexthdr[1];
228	}
229
230out:
231	kfree(tmp_hdr);
232out_nofree:
233	return ret;
234}
235
236static u32 esp6_get_max_size(struct xfrm_state *x, int mtu)
237{
238	struct esp_data *esp = x->data;
239	u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4);
240
241	if (x->props.mode) {
242		mtu = ALIGN(mtu + 2, blksize);
243	} else {
244		/* The worst case. */
245		u32 padsize = ((blksize - 1) & 7) + 1;
246		mtu = ALIGN(mtu + 2, padsize) + blksize - padsize;
247	}
248	if (esp->conf.padlen)
249		mtu = ALIGN(mtu, esp->conf.padlen);
250
251	return mtu + x->props.header_len + esp->auth.icv_trunc_len;
252}
253
254static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
255                     int type, int code, int offset, __u32 info)
256{
257	struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
258	struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset);
259	struct xfrm_state *x;
260
261	if (type != ICMPV6_DEST_UNREACH &&
262	    type != ICMPV6_PKT_TOOBIG)
263		return;
264
265	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6);
266	if (!x)
267		return;
268	printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/"
269			"%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
270			ntohl(esph->spi), NIP6(iph->daddr));
271	xfrm_state_put(x);
272}
273
274static void esp6_destroy(struct xfrm_state *x)
275{
276	struct esp_data *esp = x->data;
277
278	if (!esp)
279		return;
280
281	crypto_free_tfm(esp->conf.tfm);
282	esp->conf.tfm = NULL;
283	kfree(esp->conf.ivec);
284	esp->conf.ivec = NULL;
285	crypto_free_tfm(esp->auth.tfm);
286	esp->auth.tfm = NULL;
287	kfree(esp->auth.work_icv);
288	esp->auth.work_icv = NULL;
289	kfree(esp);
290}
291
292static int esp6_init_state(struct xfrm_state *x)
293{
294	struct esp_data *esp = NULL;
295
296	/* null auth and encryption can have zero length keys */
297	if (x->aalg) {
298		if (x->aalg->alg_key_len > 512)
299			goto error;
300	}
301	if (x->ealg == NULL)
302		goto error;
303
304	if (x->encap)
305		goto error;
306
307	esp = kmalloc(sizeof(*esp), GFP_KERNEL);
308	if (esp == NULL)
309		return -ENOMEM;
310
311	memset(esp, 0, sizeof(*esp));
312
313	if (x->aalg) {
314		struct xfrm_algo_desc *aalg_desc;
315
316		esp->auth.key = x->aalg->alg_key;
317		esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
318		esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
319		if (esp->auth.tfm == NULL)
320			goto error;
321		esp->auth.icv = esp_hmac_digest;
322
323		aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
324		BUG_ON(!aalg_desc);
325
326		if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
327			crypto_tfm_alg_digestsize(esp->auth.tfm)) {
328				printk(KERN_INFO "ESP: %s digestsize %u != %hu\n",
329					x->aalg->alg_name,
330					crypto_tfm_alg_digestsize(esp->auth.tfm),
331					aalg_desc->uinfo.auth.icv_fullbits/8);
332				goto error;
333		}
334
335		esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
336		esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
337
338		esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
339		if (!esp->auth.work_icv)
340			goto error;
341	}
342	esp->conf.key = x->ealg->alg_key;
343	esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
344	if (x->props.ealgo == SADB_EALG_NULL)
345		esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB);
346	else
347		esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC);
348	if (esp->conf.tfm == NULL)
349		goto error;
350	esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm);
351	esp->conf.padlen = 0;
352	if (esp->conf.ivlen) {
353		esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
354		if (unlikely(esp->conf.ivec == NULL))
355			goto error;
356		get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
357	}
358	if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len))
359		goto error;
360	x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen;
361	if (x->props.mode)
362		x->props.header_len += sizeof(struct ipv6hdr);
363	x->data = esp;
364	return 0;
365
366error:
367	x->data = esp;
368	esp6_destroy(x);
369	x->data = NULL;
370	return -EINVAL;
371}
372
373static struct xfrm_type esp6_type =
374{
375	.description	= "ESP6",
376	.owner	     	= THIS_MODULE,
377	.proto	     	= IPPROTO_ESP,
378	.init_state	= esp6_init_state,
379	.destructor	= esp6_destroy,
380	.get_max_size	= esp6_get_max_size,
381	.input		= esp6_input,
382	.output		= esp6_output
383};
384
385static struct inet6_protocol esp6_protocol = {
386	.handler 	=	xfrm6_rcv,
387	.err_handler	=	esp6_err,
388	.flags		=	INET6_PROTO_NOPOLICY,
389};
390
391static int __init esp6_init(void)
392{
393	if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
394		printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n");
395		return -EAGAIN;
396	}
397	if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
398		printk(KERN_INFO "ipv6 esp init: can't add protocol\n");
399		xfrm_unregister_type(&esp6_type, AF_INET6);
400		return -EAGAIN;
401	}
402
403	return 0;
404}
405
406static void __exit esp6_fini(void)
407{
408	if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
409		printk(KERN_INFO "ipv6 esp close: can't remove protocol\n");
410	if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
411		printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n");
412}
413
414module_init(esp6_init);
415module_exit(esp6_fini);
416
417MODULE_LICENSE("GPL");
418