xref: /openbmc/linux/net/ipv6/esp6.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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 
41 static 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 
127 error:
128 	return err;
129 }
130 
131 static 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 
230 out:
231 	kfree(tmp_hdr);
232 out_nofree:
233 	return ret;
234 }
235 
236 static 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_full_len;
252 }
253 
254 static 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 
274 static 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 
292 static 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 
366 error:
367 	x->data = esp;
368 	esp6_destroy(x);
369 	x->data = NULL;
370 	return -EINVAL;
371 }
372 
373 static 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 
385 static struct inet6_protocol esp6_protocol = {
386 	.handler 	=	xfrm6_rcv,
387 	.err_handler	=	esp6_err,
388 	.flags		=	INET6_PROTO_NOPOLICY,
389 };
390 
391 static 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 
406 static 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 
414 module_init(esp6_init);
415 module_exit(esp6_fini);
416 
417 MODULE_LICENSE("GPL");
418