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[IPv6] ESP: Discard dummy packets introduced in rfc4303
[linux-2.6/zen-sources.git] / net / ipv6 / esp6.c
blob44405325467626a5ca473ef647872ec8cdb14753
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/err.h>
28 #include <linux/module.h>
29 #include <net/ip.h>
30 #include <net/xfrm.h>
31 #include <net/esp.h>
32 #include <linux/scatterlist.h>
33 #include <linux/crypto.h>
34 #include <linux/kernel.h>
35 #include <linux/pfkeyv2.h>
36 #include <linux/random.h>
37 #include <linux/spinlock.h>
38 #include <net/icmp.h>
39 #include <net/ipv6.h>
40 #include <net/protocol.h>
41 #include <linux/icmpv6.h>
42
43 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
44 {
45 int err;
46 struct ip_esp_hdr *esph;
47 struct crypto_blkcipher *tfm;
48 struct blkcipher_desc desc;
49 struct sk_buff *trailer;
50 int blksize;
51 int clen;
52 int alen;
53 int nfrags;
54 u8 *tail;
55 struct esp_data *esp = x->data;
56
57 /* skb is pure payload to encrypt */
58 err = -ENOMEM;
59
60 /* Round to block size */
61 clen = skb->len;
62
63 alen = esp->auth.icv_trunc_len;
64 tfm = esp->conf.tfm;
65 desc.tfm = tfm;
66 desc.flags = 0;
67 blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
68 clen = ALIGN(clen + 2, blksize);
69 if (esp->conf.padlen)
70 clen = ALIGN(clen, esp->conf.padlen);
71
72 if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) {
73 goto error;
74 }
75
76 /* Fill padding... */
77 tail = skb_tail_pointer(trailer);
78 do {
79 int i;
80 for (i=0; i<clen-skb->len - 2; i++)
81 tail[i] = i + 1;
82 } while (0);
83 tail[clen-skb->len - 2] = (clen - skb->len) - 2;
84 pskb_put(skb, trailer, clen - skb->len);
85
86 skb_push(skb, -skb_network_offset(skb));
87 esph = ip_esp_hdr(skb);
88 *(skb_tail_pointer(trailer) - 1) = *skb_mac_header(skb);
89 *skb_mac_header(skb) = IPPROTO_ESP;
90
91 esph->spi = x->id.spi;
92 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq);
93
94 spin_lock_bh(&x->lock);
95
96 if (esp->conf.ivlen) {
97 if (unlikely(!esp->conf.ivinitted)) {
98 get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
99 esp->conf.ivinitted = 1;
100 }
101 crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
102 }
103
104 do {
105 struct scatterlist *sg = &esp->sgbuf[0];
106
107 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
108 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
109 if (!sg)
110 goto unlock;
111 }
112 sg_init_table(sg, nfrags);
113 skb_to_sgvec(skb, sg,
114 esph->enc_data +
115 esp->conf.ivlen -
116 skb->data, clen);
117 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
118 if (unlikely(sg != &esp->sgbuf[0]))
119 kfree(sg);
120 } while (0);
121
122 if (unlikely(err))
123 goto unlock;
124
125 if (esp->conf.ivlen) {
126 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
127 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
128 }
129
130 if (esp->auth.icv_full_len) {
131 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
132 sizeof(*esph) + esp->conf.ivlen + clen);
133 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
134 }
135
136 unlock:
137 spin_unlock_bh(&x->lock);
138
139 error:
140 return err;
141 }
142
143 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
144 {
145 struct ipv6hdr *iph;
146 struct ip_esp_hdr *esph;
147 struct esp_data *esp = x->data;
148 struct crypto_blkcipher *tfm = esp->conf.tfm;
149 struct blkcipher_desc desc = { .tfm = tfm };
150 struct sk_buff *trailer;
151 int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
152 int alen = esp->auth.icv_trunc_len;
153 int elen = skb->len - sizeof(*esph) - esp->conf.ivlen - alen;
154 int hdr_len = skb_network_header_len(skb);
155 int nfrags;
156 int ret = 0;
157
158 if (!pskb_may_pull(skb, sizeof(*esph))) {
159 ret = -EINVAL;
160 goto out;
161 }
162
163 if (elen <= 0 || (elen & (blksize-1))) {
164 ret = -EINVAL;
165 goto out;
166 }
167
168 /* If integrity check is required, do this. */
169 if (esp->auth.icv_full_len) {
170 u8 sum[alen];
171
172 ret = esp_mac_digest(esp, skb, 0, skb->len - alen);
173 if (ret)
174 goto out;
175
176 if (skb_copy_bits(skb, skb->len - alen, sum, alen))
177 BUG();
178
179 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
180 x->stats.integrity_failed++;
181 ret = -EINVAL;
182 goto out;
183 }
184 }
185
186 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
187 ret = -EINVAL;
188 goto out;
189 }
190
191 skb->ip_summed = CHECKSUM_NONE;
192
193 esph = (struct ip_esp_hdr *)skb->data;
194 iph = ipv6_hdr(skb);
195
196 /* Get ivec. This can be wrong, check against another impls. */
197 if (esp->conf.ivlen)
198 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
199
200 {
201 u8 nexthdr[2];
202 struct scatterlist *sg = &esp->sgbuf[0];
203 u8 padlen;
204
205 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
206 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
207 if (!sg) {
208 ret = -ENOMEM;
209 goto out;
210 }
211 }
212 sg_init_table(sg, nfrags);
213 skb_to_sgvec(skb, sg,
214 sizeof(*esph) + esp->conf.ivlen,
215 elen);
216 ret = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
217 if (unlikely(sg != &esp->sgbuf[0]))
218 kfree(sg);
219 if (unlikely(ret))
220 goto out;
221
222 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
223 BUG();
224
225 padlen = nexthdr[0];
226 if (padlen+2 >= elen) {
227 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen);
228 ret = -EINVAL;
229 goto out;
230 }
231 /* ... check padding bits here. Silly. :-) */
232
233 /* RFC4303: Drop dummy packets without any error */
234 if (nexthdr[1] == IPPROTO_NONE) {
235 ret = -EINVAL;
236 goto out;
237 }
238
239 pskb_trim(skb, skb->len - alen - padlen - 2);
240 ret = nexthdr[1];
241 }
242
243 __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen);
244 skb_set_transport_header(skb, -hdr_len);
245 out:
246 return ret;
247 }
248
249 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu)
250 {
251 struct esp_data *esp = x->data;
252 u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
253 u32 align = max_t(u32, blksize, esp->conf.padlen);
254 u32 rem;
255
256 mtu -= x->props.header_len + esp->auth.icv_trunc_len;
257 rem = mtu & (align - 1);
258 mtu &= ~(align - 1);
259
260 if (x->props.mode != XFRM_MODE_TUNNEL) {
261 u32 padsize = ((blksize - 1) & 7) + 1;
262 mtu -= blksize - padsize;
263 mtu += min_t(u32, blksize - padsize, rem);
264 }
265
266 return mtu - 2;
267 }
268
269 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
270 int type, int code, int offset, __be32 info)
271 {
272 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
273 struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset);
274 struct xfrm_state *x;
275
276 if (type != ICMPV6_DEST_UNREACH &&
277 type != ICMPV6_PKT_TOOBIG)
278 return;
279
280 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6);
281 if (!x)
282 return;
283 printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n",
284 ntohl(esph->spi), NIP6(iph->daddr));
285 xfrm_state_put(x);
286 }
287
288 static void esp6_destroy(struct xfrm_state *x)
289 {
290 struct esp_data *esp = x->data;
291
292 if (!esp)
293 return;
294
295 crypto_free_blkcipher(esp->conf.tfm);
296 esp->conf.tfm = NULL;
297 kfree(esp->conf.ivec);
298 esp->conf.ivec = NULL;
299 crypto_free_hash(esp->auth.tfm);
300 esp->auth.tfm = NULL;
301 kfree(esp->auth.work_icv);
302 esp->auth.work_icv = NULL;
303 kfree(esp);
304 }
305
306 static int esp6_init_state(struct xfrm_state *x)
307 {
308 struct esp_data *esp = NULL;
309 struct crypto_blkcipher *tfm;
310
311 if (x->ealg == NULL)
312 goto error;
313
314 if (x->encap)
315 goto error;
316
317 esp = kzalloc(sizeof(*esp), GFP_KERNEL);
318 if (esp == NULL)
319 return -ENOMEM;
320
321 if (x->aalg) {
322 struct xfrm_algo_desc *aalg_desc;
323 struct crypto_hash *hash;
324
325 hash = crypto_alloc_hash(x->aalg->alg_name, 0,
326 CRYPTO_ALG_ASYNC);
327 if (IS_ERR(hash))
328 goto error;
329
330 esp->auth.tfm = hash;
331 if (crypto_hash_setkey(hash, x->aalg->alg_key,
332 (x->aalg->alg_key_len + 7) / 8))
333 goto error;
334
335 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
336 BUG_ON(!aalg_desc);
337
338 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
339 crypto_hash_digestsize(hash)) {
340 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
341 x->aalg->alg_name,
342 crypto_hash_digestsize(hash),
343 aalg_desc->uinfo.auth.icv_fullbits/8);
344 goto error;
345 }
346
347 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
348 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
349
350 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
351 if (!esp->auth.work_icv)
352 goto error;
353 }
354 tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
355 if (IS_ERR(tfm))
356 goto error;
357 esp->conf.tfm = tfm;
358 esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
359 esp->conf.padlen = 0;
360 if (esp->conf.ivlen) {
361 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
362 if (unlikely(esp->conf.ivec == NULL))
363 goto error;
364 esp->conf.ivinitted = 0;
365 }
366 if (crypto_blkcipher_setkey(tfm, x->ealg->alg_key,
367 (x->ealg->alg_key_len + 7) / 8))
368 goto error;
369 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
370 switch (x->props.mode) {
371 case XFRM_MODE_BEET:
372 case XFRM_MODE_TRANSPORT:
373 break;
374 case XFRM_MODE_TUNNEL:
375 x->props.header_len += sizeof(struct ipv6hdr);
376 break;
377 default:
378 goto error;
379 }
380 x->data = esp;
381 return 0;
382
383 error:
384 x->data = esp;
385 esp6_destroy(x);
386 x->data = NULL;
387 return -EINVAL;
388 }
389
390 static struct xfrm_type esp6_type =
391 {
392 .description = "ESP6",
393 .owner = THIS_MODULE,
394 .proto = IPPROTO_ESP,
395 .flags = XFRM_TYPE_REPLAY_PROT,
396 .init_state = esp6_init_state,
397 .destructor = esp6_destroy,
398 .get_mtu = esp6_get_mtu,
399 .input = esp6_input,
400 .output = esp6_output,
401 .hdr_offset = xfrm6_find_1stfragopt,
402 };
403
404 static struct inet6_protocol esp6_protocol = {
405 .handler = xfrm6_rcv,
406 .err_handler = esp6_err,
407 .flags = INET6_PROTO_NOPOLICY,
408 };
409
410 static int __init esp6_init(void)
411 {
412 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
413 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n");
414 return -EAGAIN;
415 }
416 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
417 printk(KERN_INFO "ipv6 esp init: can't add protocol\n");
418 xfrm_unregister_type(&esp6_type, AF_INET6);
419 return -EAGAIN;
420 }
421
422 return 0;
423 }
424
425 static void __exit esp6_fini(void)
426 {
427 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
428 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n");
429 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
430 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n");
431 }
432
433 module_init(esp6_init);
434 module_exit(esp6_fini);
435
436 MODULE_LICENSE("GPL");
437 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP);
Stable & featurefull patchset based on Linus's git branch