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6b7326c8 1#include <linux/err.h>
1da177e4
LT
2#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>
a02a6422 8#include <linux/kernel.h>
1da177e4
LT
9#include <linux/pfkeyv2.h>
10#include <linux/random.h>
11#include <net/icmp.h>
14c85021 12#include <net/protocol.h>
1da177e4
LT
13#include <net/udp.h>
14
1da177e4
LT
15static 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;
6b7326c8
HX
20 struct crypto_blkcipher *tfm;
21 struct blkcipher_desc desc;
1da177e4
LT
22 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;
6b7326c8
HX
41 desc.tfm = tfm;
42 desc.flags = 0;
43 blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
a02a6422 44 clen = ALIGN(clen + 2, blksize);
1da177e4 45 if (esp->conf.padlen)
a02a6422 46 clen = ALIGN(clen, esp->conf.padlen);
1da177e4
LT
47
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
d56f90a7 60 __skb_push(skb, skb->data - skb_network_header(skb));
1da177e4 61 top_iph = skb->nh.iph;
d56f90a7
ACM
62 esph = (struct ip_esp_hdr *)(skb_network_header(skb) +
63 top_iph->ihl * 4);
1da177e4
LT
64 top_iph->tot_len = htons(skb->len + alen);
65 *(u8*)(trailer->tail - 1) = top_iph->protocol;
66
67 /* this is non-NULL only with UDP Encapsulation */
68 if (x->encap) {
69 struct xfrm_encap_tmpl *encap = x->encap;
70 struct udphdr *uh;
d5a0a1e3 71 __be32 *udpdata32;
1da177e4
LT
72
73 uh = (struct udphdr *)esph;
74 uh->source = encap->encap_sport;
75 uh->dest = encap->encap_dport;
76 uh->len = htons(skb->len + alen - top_iph->ihl*4);
77 uh->check = 0;
78
79 switch (encap->encap_type) {
80 default:
81 case UDP_ENCAP_ESPINUDP:
82 esph = (struct ip_esp_hdr *)(uh + 1);
83 break;
84 case UDP_ENCAP_ESPINUDP_NON_IKE:
d5a0a1e3 85 udpdata32 = (__be32 *)(uh + 1);
1da177e4
LT
86 udpdata32[0] = udpdata32[1] = 0;
87 esph = (struct ip_esp_hdr *)(udpdata32 + 2);
88 break;
89 }
90
91 top_iph->protocol = IPPROTO_UDP;
92 } else
93 top_iph->protocol = IPPROTO_ESP;
94
95 esph->spi = x->id.spi;
96 esph->seq_no = htonl(++x->replay.oseq);
9500e8a8 97 xfrm_aevent_doreplay(x);
1da177e4 98
e4bec827
DM
99 if (esp->conf.ivlen) {
100 if (unlikely(!esp->conf.ivinitted)) {
101 get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
102 esp->conf.ivinitted = 1;
103 }
6b7326c8 104 crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
e4bec827 105 }
1da177e4
LT
106
107 do {
108 struct scatterlist *sg = &esp->sgbuf[0];
109
110 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
111 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
112 if (!sg)
113 goto error;
114 }
115 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
6b7326c8 116 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
1da177e4
LT
117 if (unlikely(sg != &esp->sgbuf[0]))
118 kfree(sg);
119 } while (0);
120
6b7326c8
HX
121 if (unlikely(err))
122 goto error;
123
1da177e4 124 if (esp->conf.ivlen) {
6b7326c8
HX
125 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
126 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
1da177e4
LT
127 }
128
129 if (esp->auth.icv_full_len) {
07d4ee58
HX
130 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
131 sizeof(*esph) + esp->conf.ivlen + clen);
132 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
1da177e4
LT
133 }
134
135 ip_send_check(top_iph);
136
1da177e4
LT
137error:
138 return err;
139}
140
141/*
142 * Note: detecting truncated vs. non-truncated authentication data is very
143 * expensive, so we only support truncated data, which is the recommended
144 * and common case.
145 */
e695633e 146static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
1da177e4
LT
147{
148 struct iphdr *iph;
149 struct ip_esp_hdr *esph;
150 struct esp_data *esp = x->data;
6b7326c8
HX
151 struct crypto_blkcipher *tfm = esp->conf.tfm;
152 struct blkcipher_desc desc = { .tfm = tfm };
1da177e4 153 struct sk_buff *trailer;
6b7326c8 154 int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
1da177e4
LT
155 int alen = esp->auth.icv_trunc_len;
156 int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen;
157 int nfrags;
31a4ab93 158 int ihl;
4bf05ece
HX
159 u8 nexthdr[2];
160 struct scatterlist *sg;
4bf05ece 161 int padlen;
6b7326c8 162 int err;
1da177e4
LT
163
164 if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr)))
165 goto out;
166
167 if (elen <= 0 || (elen & (blksize-1)))
168 goto out;
169
170 /* If integrity check is required, do this. */
171 if (esp->auth.icv_full_len) {
07d4ee58 172 u8 sum[alen];
1da177e4 173
07d4ee58
HX
174 err = esp_mac_digest(esp, skb, 0, skb->len - alen);
175 if (err)
176 goto out;
177
178 if (skb_copy_bits(skb, skb->len - alen, sum, alen))
1da177e4
LT
179 BUG();
180
07d4ee58 181 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
1da177e4
LT
182 x->stats.integrity_failed++;
183 goto out;
184 }
185 }
186
187 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0)
188 goto out;
189
190 skb->ip_summed = CHECKSUM_NONE;
191
192 esph = (struct ip_esp_hdr*)skb->data;
1da177e4
LT
193
194 /* Get ivec. This can be wrong, check against another impls. */
195 if (esp->conf.ivlen)
6b7326c8 196 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
1da177e4 197
4bf05ece 198 sg = &esp->sgbuf[0];
1da177e4 199
4bf05ece
HX
200 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
201 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
202 if (!sg)
203 goto out;
204 }
205 skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen);
6b7326c8 206 err = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
4bf05ece
HX
207 if (unlikely(sg != &esp->sgbuf[0]))
208 kfree(sg);
6b7326c8
HX
209 if (unlikely(err))
210 return err;
1da177e4 211
4bf05ece
HX
212 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
213 BUG();
1da177e4 214
4bf05ece
HX
215 padlen = nexthdr[0];
216 if (padlen+2 >= elen)
217 goto out;
1da177e4 218
e905a9ed 219 /* ... check padding bits here. Silly. :-) */
1da177e4 220
31a4ab93
HX
221 iph = skb->nh.iph;
222 ihl = iph->ihl * 4;
223
752c1f4c
HX
224 if (x->encap) {
225 struct xfrm_encap_tmpl *encap = x->encap;
d56f90a7 226 struct udphdr *uh = (void *)(skb_network_header(skb) + ihl);
752c1f4c
HX
227
228 /*
229 * 1) if the NAT-T peer's IP or port changed then
230 * advertize the change to the keying daemon.
231 * This is an inbound SA, so just compare
232 * SRC ports.
233 */
234 if (iph->saddr != x->props.saddr.a4 ||
235 uh->source != encap->encap_sport) {
236 xfrm_address_t ipaddr;
237
238 ipaddr.a4 = iph->saddr;
239 km_new_mapping(x, &ipaddr, uh->source);
e905a9ed 240
752c1f4c
HX
241 /* XXX: perhaps add an extra
242 * policy check here, to see
243 * if we should allow or
244 * reject a packet from a
245 * different source
246 * address/port.
247 */
1da177e4 248 }
e905a9ed 249
752c1f4c
HX
250 /*
251 * 2) ignore UDP/TCP checksums in case
252 * of NAT-T in Transport Mode, or
253 * perform other post-processing fixes
254 * as per draft-ietf-ipsec-udp-encaps-06,
255 * section 3.1.2
256 */
0a69452c
DB
257 if (x->props.mode == XFRM_MODE_TRANSPORT ||
258 x->props.mode == XFRM_MODE_BEET)
752c1f4c 259 skb->ip_summed = CHECKSUM_UNNECESSARY;
1da177e4
LT
260 }
261
4bf05ece
HX
262 iph->protocol = nexthdr[1];
263 pskb_trim(skb, skb->len - alen - padlen - 2);
31a4ab93 264 skb->h.raw = __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen) - ihl;
4bf05ece 265
1da177e4
LT
266 return 0;
267
268out:
269 return -EINVAL;
270}
271
1da177e4
LT
272static u32 esp4_get_max_size(struct xfrm_state *x, int mtu)
273{
274 struct esp_data *esp = x->data;
6b7326c8 275 u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
0a69452c
DB
276 int enclen = 0;
277
278 switch (x->props.mode) {
279 case XFRM_MODE_TUNNEL:
280 mtu = ALIGN(mtu +2, blksize);
281 break;
282 default:
283 case XFRM_MODE_TRANSPORT:
284 /* The worst case */
d4875b04 285 mtu = ALIGN(mtu + 2, 4) + blksize - 4;
0a69452c
DB
286 break;
287 case XFRM_MODE_BEET:
e905a9ed 288 /* The worst case. */
0a69452c
DB
289 enclen = IPV4_BEET_PHMAXLEN;
290 mtu = ALIGN(mtu + enclen + 2, blksize);
291 break;
1da177e4 292 }
0a69452c 293
1da177e4 294 if (esp->conf.padlen)
a02a6422 295 mtu = ALIGN(mtu, esp->conf.padlen);
1da177e4 296
0a69452c 297 return mtu + x->props.header_len + esp->auth.icv_trunc_len - enclen;
1da177e4
LT
298}
299
300static void esp4_err(struct sk_buff *skb, u32 info)
301{
302 struct iphdr *iph = (struct iphdr*)skb->data;
303 struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2));
304 struct xfrm_state *x;
305
306 if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
307 skb->h.icmph->code != ICMP_FRAG_NEEDED)
308 return;
309
310 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET);
311 if (!x)
312 return;
64ce2073
PM
313 NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
314 ntohl(esph->spi), ntohl(iph->daddr));
1da177e4
LT
315 xfrm_state_put(x);
316}
317
318static void esp_destroy(struct xfrm_state *x)
319{
320 struct esp_data *esp = x->data;
321
322 if (!esp)
323 return;
324
6b7326c8 325 crypto_free_blkcipher(esp->conf.tfm);
573dbd95
JJ
326 esp->conf.tfm = NULL;
327 kfree(esp->conf.ivec);
328 esp->conf.ivec = NULL;
07d4ee58 329 crypto_free_hash(esp->auth.tfm);
573dbd95
JJ
330 esp->auth.tfm = NULL;
331 kfree(esp->auth.work_icv);
332 esp->auth.work_icv = NULL;
1da177e4
LT
333 kfree(esp);
334}
335
72cb6962 336static int esp_init_state(struct xfrm_state *x)
1da177e4
LT
337{
338 struct esp_data *esp = NULL;
6b7326c8 339 struct crypto_blkcipher *tfm;
1da177e4
LT
340
341 /* null auth and encryption can have zero length keys */
342 if (x->aalg) {
343 if (x->aalg->alg_key_len > 512)
344 goto error;
345 }
346 if (x->ealg == NULL)
347 goto error;
348
0da974f4 349 esp = kzalloc(sizeof(*esp), GFP_KERNEL);
1da177e4
LT
350 if (esp == NULL)
351 return -ENOMEM;
352
1da177e4
LT
353 if (x->aalg) {
354 struct xfrm_algo_desc *aalg_desc;
07d4ee58 355 struct crypto_hash *hash;
1da177e4
LT
356
357 esp->auth.key = x->aalg->alg_key;
358 esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
07d4ee58
HX
359 hash = crypto_alloc_hash(x->aalg->alg_name, 0,
360 CRYPTO_ALG_ASYNC);
361 if (IS_ERR(hash))
362 goto error;
363
364 esp->auth.tfm = hash;
365 if (crypto_hash_setkey(hash, esp->auth.key, esp->auth.key_len))
1da177e4 366 goto error;
1da177e4
LT
367
368 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
369 BUG_ON(!aalg_desc);
370
371 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
07d4ee58 372 crypto_hash_digestsize(hash)) {
64ce2073
PM
373 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
374 x->aalg->alg_name,
07d4ee58 375 crypto_hash_digestsize(hash),
64ce2073 376 aalg_desc->uinfo.auth.icv_fullbits/8);
1da177e4
LT
377 goto error;
378 }
379
380 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
381 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
382
383 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
384 if (!esp->auth.work_icv)
385 goto error;
386 }
387 esp->conf.key = x->ealg->alg_key;
388 esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
6b7326c8
HX
389 tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
390 if (IS_ERR(tfm))
1da177e4 391 goto error;
6b7326c8
HX
392 esp->conf.tfm = tfm;
393 esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
1da177e4
LT
394 esp->conf.padlen = 0;
395 if (esp->conf.ivlen) {
396 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
397 if (unlikely(esp->conf.ivec == NULL))
398 goto error;
e4bec827 399 esp->conf.ivinitted = 0;
1da177e4 400 }
6b7326c8 401 if (crypto_blkcipher_setkey(tfm, esp->conf.key, esp->conf.key_len))
1da177e4
LT
402 goto error;
403 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
7e49e6de 404 if (x->props.mode == XFRM_MODE_TUNNEL)
1da177e4
LT
405 x->props.header_len += sizeof(struct iphdr);
406 if (x->encap) {
407 struct xfrm_encap_tmpl *encap = x->encap;
408
409 switch (encap->encap_type) {
410 default:
411 goto error;
412 case UDP_ENCAP_ESPINUDP:
413 x->props.header_len += sizeof(struct udphdr);
414 break;
415 case UDP_ENCAP_ESPINUDP_NON_IKE:
416 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
417 break;
418 }
419 }
420 x->data = esp;
421 x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len;
422 return 0;
423
424error:
425 x->data = esp;
426 esp_destroy(x);
427 x->data = NULL;
428 return -EINVAL;
429}
430
431static struct xfrm_type esp_type =
432{
433 .description = "ESP4",
434 .owner = THIS_MODULE,
435 .proto = IPPROTO_ESP,
436 .init_state = esp_init_state,
437 .destructor = esp_destroy,
438 .get_max_size = esp4_get_max_size,
439 .input = esp_input,
1da177e4
LT
440 .output = esp_output
441};
442
443static struct net_protocol esp4_protocol = {
444 .handler = xfrm4_rcv,
445 .err_handler = esp4_err,
446 .no_policy = 1,
447};
448
449static int __init esp4_init(void)
450{
1da177e4
LT
451 if (xfrm_register_type(&esp_type, AF_INET) < 0) {
452 printk(KERN_INFO "ip esp init: can't add xfrm type\n");
453 return -EAGAIN;
454 }
455 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) {
456 printk(KERN_INFO "ip esp init: can't add protocol\n");
457 xfrm_unregister_type(&esp_type, AF_INET);
458 return -EAGAIN;
459 }
460 return 0;
461}
462
463static void __exit esp4_fini(void)
464{
465 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0)
466 printk(KERN_INFO "ip esp close: can't remove protocol\n");
467 if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
468 printk(KERN_INFO "ip esp close: can't remove xfrm type\n");
469}
470
471module_init(esp4_init);
472module_exit(esp4_fini);
473MODULE_LICENSE("GPL");