blob: b428489f6ccd90f7226be6000763915ee3c2eeec [file] [log] [blame]
Herbert Xu6b7326c2006-07-30 15:41:01 +10001#include <linux/err.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002#include <linux/module.h>
3#include <net/ip.h>
4#include <net/xfrm.h>
5#include <net/esp.h>
6#include <asm/scatterlist.h>
7#include <linux/crypto.h>
Herbert Xua02a6422005-10-10 21:11:08 -07008#include <linux/kernel.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07009#include <linux/pfkeyv2.h>
10#include <linux/random.h>
11#include <net/icmp.h>
Arnaldo Carvalho de Melo14c85022005-12-27 02:43:12 -020012#include <net/protocol.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070013#include <net/udp.h>
14
Linus Torvalds1da177e2005-04-16 15:20:36 -070015static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
16{
17 int err;
18 struct iphdr *top_iph;
19 struct ip_esp_hdr *esph;
Herbert Xu6b7326c2006-07-30 15:41:01 +100020 struct crypto_blkcipher *tfm;
21 struct blkcipher_desc desc;
Linus Torvalds1da177e2005-04-16 15:20:36 -070022 struct esp_data *esp;
23 struct sk_buff *trailer;
24 int blksize;
25 int clen;
26 int alen;
27 int nfrags;
28
29 /* Strip IP+ESP header. */
30 __skb_pull(skb, skb->h.raw - skb->data);
31 /* Now skb is pure payload to encrypt */
32
33 err = -ENOMEM;
34
35 /* Round to block size */
36 clen = skb->len;
37
38 esp = x->data;
39 alen = esp->auth.icv_trunc_len;
40 tfm = esp->conf.tfm;
Herbert Xu6b7326c2006-07-30 15:41:01 +100041 desc.tfm = tfm;
42 desc.flags = 0;
43 blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
Herbert Xua02a6422005-10-10 21:11:08 -070044 clen = ALIGN(clen + 2, blksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -070045 if (esp->conf.padlen)
Herbert Xua02a6422005-10-10 21:11:08 -070046 clen = ALIGN(clen, esp->conf.padlen);
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
48 if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0)
49 goto error;
50
51 /* Fill padding... */
52 do {
53 int i;
54 for (i=0; i<clen-skb->len - 2; i++)
55 *(u8*)(trailer->tail + i) = i+1;
56 } while (0);
57 *(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2;
58 pskb_put(skb, trailer, clen - skb->len);
59
60 __skb_push(skb, skb->data - skb->nh.raw);
61 top_iph = skb->nh.iph;
62 esph = (struct ip_esp_hdr *)(skb->nh.raw + top_iph->ihl*4);
63 top_iph->tot_len = htons(skb->len + alen);
64 *(u8*)(trailer->tail - 1) = top_iph->protocol;
65
66 /* this is non-NULL only with UDP Encapsulation */
67 if (x->encap) {
68 struct xfrm_encap_tmpl *encap = x->encap;
69 struct udphdr *uh;
70 u32 *udpdata32;
71
72 uh = (struct udphdr *)esph;
73 uh->source = encap->encap_sport;
74 uh->dest = encap->encap_dport;
75 uh->len = htons(skb->len + alen - top_iph->ihl*4);
76 uh->check = 0;
77
78 switch (encap->encap_type) {
79 default:
80 case UDP_ENCAP_ESPINUDP:
81 esph = (struct ip_esp_hdr *)(uh + 1);
82 break;
83 case UDP_ENCAP_ESPINUDP_NON_IKE:
84 udpdata32 = (u32 *)(uh + 1);
85 udpdata32[0] = udpdata32[1] = 0;
86 esph = (struct ip_esp_hdr *)(udpdata32 + 2);
87 break;
88 }
89
90 top_iph->protocol = IPPROTO_UDP;
91 } else
92 top_iph->protocol = IPPROTO_ESP;
93
94 esph->spi = x->id.spi;
95 esph->seq_no = htonl(++x->replay.oseq);
Jamal Hadi Salim9500e8a2006-03-20 19:15:29 -080096 xfrm_aevent_doreplay(x);
Linus Torvalds1da177e2005-04-16 15:20:36 -070097
98 if (esp->conf.ivlen)
Herbert Xu6b7326c2006-07-30 15:41:01 +100099 crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100
101 do {
102 struct scatterlist *sg = &esp->sgbuf[0];
103
104 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
105 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
106 if (!sg)
107 goto error;
108 }
109 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
Herbert Xu6b7326c2006-07-30 15:41:01 +1000110 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 if (unlikely(sg != &esp->sgbuf[0]))
112 kfree(sg);
113 } while (0);
114
Herbert Xu6b7326c2006-07-30 15:41:01 +1000115 if (unlikely(err))
116 goto error;
117
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 if (esp->conf.ivlen) {
Herbert Xu6b7326c2006-07-30 15:41:01 +1000119 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
120 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 }
122
123 if (esp->auth.icv_full_len) {
Herbert Xu07d4ee52006-08-20 14:24:50 +1000124 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
125 sizeof(*esph) + esp->conf.ivlen + clen);
126 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 }
128
129 ip_send_check(top_iph);
130
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131error:
132 return err;
133}
134
135/*
136 * Note: detecting truncated vs. non-truncated authentication data is very
137 * expensive, so we only support truncated data, which is the recommended
138 * and common case.
139 */
Herbert Xue6956332006-04-01 00:52:46 -0800140static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141{
142 struct iphdr *iph;
143 struct ip_esp_hdr *esph;
144 struct esp_data *esp = x->data;
Herbert Xu6b7326c2006-07-30 15:41:01 +1000145 struct crypto_blkcipher *tfm = esp->conf.tfm;
146 struct blkcipher_desc desc = { .tfm = tfm };
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 struct sk_buff *trailer;
Herbert Xu6b7326c2006-07-30 15:41:01 +1000148 int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 int alen = esp->auth.icv_trunc_len;
150 int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen;
151 int nfrags;
Herbert Xu31a4ab92006-05-27 23:06:13 -0700152 int ihl;
Herbert Xu4bf05ec2006-02-27 13:00:01 -0800153 u8 nexthdr[2];
154 struct scatterlist *sg;
Herbert Xu4bf05ec2006-02-27 13:00:01 -0800155 int padlen;
Herbert Xu6b7326c2006-07-30 15:41:01 +1000156 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157
158 if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr)))
159 goto out;
160
161 if (elen <= 0 || (elen & (blksize-1)))
162 goto out;
163
164 /* If integrity check is required, do this. */
165 if (esp->auth.icv_full_len) {
Herbert Xu07d4ee52006-08-20 14:24:50 +1000166 u8 sum[alen];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167
Herbert Xu07d4ee52006-08-20 14:24:50 +1000168 err = esp_mac_digest(esp, skb, 0, skb->len - alen);
169 if (err)
170 goto out;
171
172 if (skb_copy_bits(skb, skb->len - alen, sum, alen))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 BUG();
174
Herbert Xu07d4ee52006-08-20 14:24:50 +1000175 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 x->stats.integrity_failed++;
177 goto out;
178 }
179 }
180
181 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0)
182 goto out;
183
184 skb->ip_summed = CHECKSUM_NONE;
185
186 esph = (struct ip_esp_hdr*)skb->data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187
188 /* Get ivec. This can be wrong, check against another impls. */
189 if (esp->conf.ivlen)
Herbert Xu6b7326c2006-07-30 15:41:01 +1000190 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191
Herbert Xu4bf05ec2006-02-27 13:00:01 -0800192 sg = &esp->sgbuf[0];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193
Herbert Xu4bf05ec2006-02-27 13:00:01 -0800194 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
195 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
196 if (!sg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198 }
Herbert Xu4bf05ec2006-02-27 13:00:01 -0800199 skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen);
Herbert Xu6b7326c2006-07-30 15:41:01 +1000200 err = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
Herbert Xu4bf05ec2006-02-27 13:00:01 -0800201 if (unlikely(sg != &esp->sgbuf[0]))
202 kfree(sg);
Herbert Xu6b7326c2006-07-30 15:41:01 +1000203 if (unlikely(err))
204 return err;
Herbert Xu4bf05ec2006-02-27 13:00:01 -0800205
206 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
207 BUG();
208
209 padlen = nexthdr[0];
210 if (padlen+2 >= elen)
211 goto out;
212
213 /* ... check padding bits here. Silly. :-) */
214
Herbert Xu31a4ab92006-05-27 23:06:13 -0700215 iph = skb->nh.iph;
216 ihl = iph->ihl * 4;
217
Herbert Xu752c1f42006-02-27 13:00:40 -0800218 if (x->encap) {
219 struct xfrm_encap_tmpl *encap = x->encap;
Herbert Xu31a4ab92006-05-27 23:06:13 -0700220 struct udphdr *uh = (void *)(skb->nh.raw + ihl);
Herbert Xu752c1f42006-02-27 13:00:40 -0800221
222 /*
223 * 1) if the NAT-T peer's IP or port changed then
224 * advertize the change to the keying daemon.
225 * This is an inbound SA, so just compare
226 * SRC ports.
227 */
228 if (iph->saddr != x->props.saddr.a4 ||
229 uh->source != encap->encap_sport) {
230 xfrm_address_t ipaddr;
231
232 ipaddr.a4 = iph->saddr;
233 km_new_mapping(x, &ipaddr, uh->source);
234
235 /* XXX: perhaps add an extra
236 * policy check here, to see
237 * if we should allow or
238 * reject a packet from a
239 * different source
240 * address/port.
241 */
Herbert Xu4bf05ec2006-02-27 13:00:01 -0800242 }
Herbert Xu752c1f42006-02-27 13:00:40 -0800243
244 /*
245 * 2) ignore UDP/TCP checksums in case
246 * of NAT-T in Transport Mode, or
247 * perform other post-processing fixes
248 * as per draft-ietf-ipsec-udp-encaps-06,
249 * section 3.1.2
250 */
251 if (!x->props.mode)
252 skb->ip_summed = CHECKSUM_UNNECESSARY;
Herbert Xu4bf05ec2006-02-27 13:00:01 -0800253 }
254
255 iph->protocol = nexthdr[1];
256 pskb_trim(skb, skb->len - alen - padlen - 2);
Herbert Xu31a4ab92006-05-27 23:06:13 -0700257 skb->h.raw = __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen) - ihl;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258
259 return 0;
260
261out:
262 return -EINVAL;
263}
264
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265static u32 esp4_get_max_size(struct xfrm_state *x, int mtu)
266{
267 struct esp_data *esp = x->data;
Herbert Xu6b7326c2006-07-30 15:41:01 +1000268 u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269
270 if (x->props.mode) {
Herbert Xua02a6422005-10-10 21:11:08 -0700271 mtu = ALIGN(mtu + 2, blksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272 } else {
273 /* The worst case. */
Herbert Xud4875b02005-10-10 21:11:34 -0700274 mtu = ALIGN(mtu + 2, 4) + blksize - 4;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 }
276 if (esp->conf.padlen)
Herbert Xua02a6422005-10-10 21:11:08 -0700277 mtu = ALIGN(mtu, esp->conf.padlen);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278
279 return mtu + x->props.header_len + esp->auth.icv_trunc_len;
280}
281
282static void esp4_err(struct sk_buff *skb, u32 info)
283{
284 struct iphdr *iph = (struct iphdr*)skb->data;
285 struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2));
286 struct xfrm_state *x;
287
288 if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
289 skb->h.icmph->code != ICMP_FRAG_NEEDED)
290 return;
291
292 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET);
293 if (!x)
294 return;
Patrick McHardy64ce2072005-08-09 20:50:53 -0700295 NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
296 ntohl(esph->spi), ntohl(iph->daddr));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 xfrm_state_put(x);
298}
299
300static void esp_destroy(struct xfrm_state *x)
301{
302 struct esp_data *esp = x->data;
303
304 if (!esp)
305 return;
306
Herbert Xu6b7326c2006-07-30 15:41:01 +1000307 crypto_free_blkcipher(esp->conf.tfm);
Jesper Juhl573dbd92005-09-01 17:44:29 -0700308 esp->conf.tfm = NULL;
309 kfree(esp->conf.ivec);
310 esp->conf.ivec = NULL;
Herbert Xu07d4ee52006-08-20 14:24:50 +1000311 crypto_free_hash(esp->auth.tfm);
Jesper Juhl573dbd92005-09-01 17:44:29 -0700312 esp->auth.tfm = NULL;
313 kfree(esp->auth.work_icv);
314 esp->auth.work_icv = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315 kfree(esp);
316}
317
Herbert Xu72cb6962005-06-20 13:18:08 -0700318static int esp_init_state(struct xfrm_state *x)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319{
320 struct esp_data *esp = NULL;
Herbert Xu6b7326c2006-07-30 15:41:01 +1000321 struct crypto_blkcipher *tfm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322
323 /* null auth and encryption can have zero length keys */
324 if (x->aalg) {
325 if (x->aalg->alg_key_len > 512)
326 goto error;
327 }
328 if (x->ealg == NULL)
329 goto error;
330
Panagiotis Issaris0da974f2006-07-21 14:51:30 -0700331 esp = kzalloc(sizeof(*esp), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 if (esp == NULL)
333 return -ENOMEM;
334
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 if (x->aalg) {
336 struct xfrm_algo_desc *aalg_desc;
Herbert Xu07d4ee52006-08-20 14:24:50 +1000337 struct crypto_hash *hash;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338
339 esp->auth.key = x->aalg->alg_key;
340 esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
Herbert Xu07d4ee52006-08-20 14:24:50 +1000341 hash = crypto_alloc_hash(x->aalg->alg_name, 0,
342 CRYPTO_ALG_ASYNC);
343 if (IS_ERR(hash))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 goto error;
Herbert Xu07d4ee52006-08-20 14:24:50 +1000345
346 esp->auth.tfm = hash;
347 if (crypto_hash_setkey(hash, esp->auth.key, esp->auth.key_len))
348 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349
350 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
351 BUG_ON(!aalg_desc);
352
353 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
Herbert Xu07d4ee52006-08-20 14:24:50 +1000354 crypto_hash_digestsize(hash)) {
Patrick McHardy64ce2072005-08-09 20:50:53 -0700355 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
356 x->aalg->alg_name,
Herbert Xu07d4ee52006-08-20 14:24:50 +1000357 crypto_hash_digestsize(hash),
Patrick McHardy64ce2072005-08-09 20:50:53 -0700358 aalg_desc->uinfo.auth.icv_fullbits/8);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 goto error;
360 }
361
362 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
363 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
364
365 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
366 if (!esp->auth.work_icv)
367 goto error;
368 }
369 esp->conf.key = x->ealg->alg_key;
370 esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
Herbert Xu6b7326c2006-07-30 15:41:01 +1000371 tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
372 if (IS_ERR(tfm))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373 goto error;
Herbert Xu6b7326c2006-07-30 15:41:01 +1000374 esp->conf.tfm = tfm;
375 esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 esp->conf.padlen = 0;
377 if (esp->conf.ivlen) {
378 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
379 if (unlikely(esp->conf.ivec == NULL))
380 goto error;
381 get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
382 }
Herbert Xu6b7326c2006-07-30 15:41:01 +1000383 if (crypto_blkcipher_setkey(tfm, esp->conf.key, esp->conf.key_len))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 goto error;
385 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
386 if (x->props.mode)
387 x->props.header_len += sizeof(struct iphdr);
388 if (x->encap) {
389 struct xfrm_encap_tmpl *encap = x->encap;
390
391 switch (encap->encap_type) {
392 default:
393 goto error;
394 case UDP_ENCAP_ESPINUDP:
395 x->props.header_len += sizeof(struct udphdr);
396 break;
397 case UDP_ENCAP_ESPINUDP_NON_IKE:
398 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
399 break;
400 }
401 }
402 x->data = esp;
403 x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len;
404 return 0;
405
406error:
407 x->data = esp;
408 esp_destroy(x);
409 x->data = NULL;
410 return -EINVAL;
411}
412
413static struct xfrm_type esp_type =
414{
415 .description = "ESP4",
416 .owner = THIS_MODULE,
417 .proto = IPPROTO_ESP,
418 .init_state = esp_init_state,
419 .destructor = esp_destroy,
420 .get_max_size = esp4_get_max_size,
421 .input = esp_input,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 .output = esp_output
423};
424
425static struct net_protocol esp4_protocol = {
426 .handler = xfrm4_rcv,
427 .err_handler = esp4_err,
428 .no_policy = 1,
429};
430
431static int __init esp4_init(void)
432{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433 if (xfrm_register_type(&esp_type, AF_INET) < 0) {
434 printk(KERN_INFO "ip esp init: can't add xfrm type\n");
435 return -EAGAIN;
436 }
437 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) {
438 printk(KERN_INFO "ip esp init: can't add protocol\n");
439 xfrm_unregister_type(&esp_type, AF_INET);
440 return -EAGAIN;
441 }
442 return 0;
443}
444
445static void __exit esp4_fini(void)
446{
447 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0)
448 printk(KERN_INFO "ip esp close: can't remove protocol\n");
449 if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
450 printk(KERN_INFO "ip esp close: can't remove xfrm type\n");
451}
452
453module_init(esp4_init);
454module_exit(esp4_fini);
455MODULE_LICENSE("GPL");