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Initial commit
[wrt350n-kernel.git] / net / ipv4 / esp4.c
blob091e6709f83109dc1e229f24bfe3cad71d5be13a
1 #include <crypto/aead.h>
2 #include <crypto/authenc.h>
3 #include <linux/err.h>
4 #include <linux/module.h>
5 #include <net/ip.h>
6 #include <net/xfrm.h>
7 #include <net/esp.h>
8 #include <linux/scatterlist.h>
9 #include <linux/kernel.h>
10 #include <linux/pfkeyv2.h>
11 #include <linux/rtnetlink.h>
12 #include <linux/slab.h>
13 #include <linux/spinlock.h>
14 #include <linux/in6.h>
15 #include <net/icmp.h>
16 #include <net/protocol.h>
17 #include <net/udp.h>
18
19 struct esp_skb_cb {
20 struct xfrm_skb_cb xfrm;
21 void *tmp;
22 };
23
24 #define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0]))
25
26 /*
27 * Allocate an AEAD request structure with extra space for SG and IV.
28 *
29 * For alignment considerations the IV is placed at the front, followed
30 * by the request and finally the SG list.
31 *
32 * TODO: Use spare space in skb for this where possible.
33 */
34 static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags)
35 {
36 unsigned int len;
37
38 len = crypto_aead_ivsize(aead);
39 if (len) {
40 len += crypto_aead_alignmask(aead) &
41 ~(crypto_tfm_ctx_alignment() - 1);
42 len = ALIGN(len, crypto_tfm_ctx_alignment());
43 }
44
45 len += sizeof(struct aead_givcrypt_request) + crypto_aead_reqsize(aead);
46 len = ALIGN(len, __alignof__(struct scatterlist));
47
48 len += sizeof(struct scatterlist) * nfrags;
49
50 return kmalloc(len, GFP_ATOMIC);
51 }
52
53 static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp)
54 {
55 return crypto_aead_ivsize(aead) ?
56 PTR_ALIGN((u8 *)tmp, crypto_aead_alignmask(aead) + 1) : tmp;
57 }
58
59 static inline struct aead_givcrypt_request *esp_tmp_givreq(
60 struct crypto_aead *aead, u8 *iv)
61 {
62 struct aead_givcrypt_request *req;
63
64 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
65 crypto_tfm_ctx_alignment());
66 aead_givcrypt_set_tfm(req, aead);
67 return req;
68 }
69
70 static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv)
71 {
72 struct aead_request *req;
73
74 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
75 crypto_tfm_ctx_alignment());
76 aead_request_set_tfm(req, aead);
77 return req;
78 }
79
80 static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead,
81 struct aead_request *req)
82 {
83 return (void *)ALIGN((unsigned long)(req + 1) +
84 crypto_aead_reqsize(aead),
85 __alignof__(struct scatterlist));
86 }
87
88 static inline struct scatterlist *esp_givreq_sg(
89 struct crypto_aead *aead, struct aead_givcrypt_request *req)
90 {
91 return (void *)ALIGN((unsigned long)(req + 1) +
92 crypto_aead_reqsize(aead),
93 __alignof__(struct scatterlist));
94 }
95
96 static void esp_output_done(struct crypto_async_request *base, int err)
97 {
98 struct sk_buff *skb = base->data;
99
100 kfree(ESP_SKB_CB(skb)->tmp);
101 xfrm_output_resume(skb, err);
102 }
103
104 static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
105 {
106 int err;
107 struct ip_esp_hdr *esph;
108 struct crypto_aead *aead;
109 struct aead_givcrypt_request *req;
110 struct scatterlist *sg;
111 struct scatterlist *asg;
112 struct esp_data *esp;
113 struct sk_buff *trailer;
114 void *tmp;
115 u8 *iv;
116 u8 *tail;
117 int blksize;
118 int clen;
119 int alen;
120 int nfrags;
121
122 /* skb is pure payload to encrypt */
123
124 err = -ENOMEM;
125
126 /* Round to block size */
127 clen = skb->len;
128
129 esp = x->data;
130 aead = esp->aead;
131 alen = crypto_aead_authsize(aead);
132
133 blksize = ALIGN(crypto_aead_blocksize(aead), 4);
134 clen = ALIGN(clen + 2, blksize);
135 if (esp->padlen)
136 clen = ALIGN(clen, esp->padlen);
137
138 if ((err = skb_cow_data(skb, clen - skb->len + alen, &trailer)) < 0)
139 goto error;
140 nfrags = err;
141
142 tmp = esp_alloc_tmp(aead, nfrags + 1);
143 if (!tmp)
144 goto error;
145
146 iv = esp_tmp_iv(aead, tmp);
147 req = esp_tmp_givreq(aead, iv);
148 asg = esp_givreq_sg(aead, req);
149 sg = asg + 1;
150
151 /* Fill padding... */
152 tail = skb_tail_pointer(trailer);
153 do {
154 int i;
155 for (i=0; i<clen-skb->len - 2; i++)
156 tail[i] = i + 1;
157 } while (0);
158 tail[clen - skb->len - 2] = (clen - skb->len) - 2;
159 tail[clen - skb->len - 1] = *skb_mac_header(skb);
160 pskb_put(skb, trailer, clen - skb->len + alen);
161
162 skb_push(skb, -skb_network_offset(skb));
163 esph = ip_esp_hdr(skb);
164 *skb_mac_header(skb) = IPPROTO_ESP;
165
166 /* this is non-NULL only with UDP Encapsulation */
167 if (x->encap) {
168 struct xfrm_encap_tmpl *encap = x->encap;
169 struct udphdr *uh;
170 __be32 *udpdata32;
171 unsigned int sport, dport;
172 int encap_type;
173
174 spin_lock_bh(&x->lock);
175 sport = encap->encap_sport;
176 dport = encap->encap_dport;
177 encap_type = encap->encap_type;
178 spin_unlock_bh(&x->lock);
179
180 uh = (struct udphdr *)esph;
181 uh->source = sport;
182 uh->dest = dport;
183 uh->len = htons(skb->len - skb_transport_offset(skb));
184 uh->check = 0;
185
186 switch (encap_type) {
187 default:
188 case UDP_ENCAP_ESPINUDP:
189 esph = (struct ip_esp_hdr *)(uh + 1);
190 break;
191 case UDP_ENCAP_ESPINUDP_NON_IKE:
192 udpdata32 = (__be32 *)(uh + 1);
193 udpdata32[0] = udpdata32[1] = 0;
194 esph = (struct ip_esp_hdr *)(udpdata32 + 2);
195 break;
196 }
197
198 *skb_mac_header(skb) = IPPROTO_UDP;
199 }
200
201 esph->spi = x->id.spi;
202 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output);
203
204 sg_init_table(sg, nfrags);
205 skb_to_sgvec(skb, sg,
206 esph->enc_data + crypto_aead_ivsize(aead) - skb->data,
207 clen + alen);
208 sg_init_one(asg, esph, sizeof(*esph));
209
210 aead_givcrypt_set_callback(req, 0, esp_output_done, skb);
211 aead_givcrypt_set_crypt(req, sg, sg, clen, iv);
212 aead_givcrypt_set_assoc(req, asg, sizeof(*esph));
213 aead_givcrypt_set_giv(req, esph->enc_data,
214 XFRM_SKB_CB(skb)->seq.output);
215
216 ESP_SKB_CB(skb)->tmp = tmp;
217 err = crypto_aead_givencrypt(req);
218 if (err == -EINPROGRESS)
219 goto error;
220
221 if (err == -EBUSY)
222 err = NET_XMIT_DROP;
223
224 kfree(tmp);
225
226 error:
227 return err;
228 }
229
230 static int esp_input_done2(struct sk_buff *skb, int err)
231 {
232 struct iphdr *iph;
233 struct xfrm_state *x = xfrm_input_state(skb);
234 struct esp_data *esp = x->data;
235 struct crypto_aead *aead = esp->aead;
236 int alen = crypto_aead_authsize(aead);
237 int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
238 int elen = skb->len - hlen;
239 int ihl;
240 u8 nexthdr[2];
241 int padlen;
242
243 kfree(ESP_SKB_CB(skb)->tmp);
244
245 if (unlikely(err))
246 goto out;
247
248 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
249 BUG();
250
251 err = -EINVAL;
252 padlen = nexthdr[0];
253 if (padlen + 2 + alen >= elen)
254 goto out;
255
256 /* ... check padding bits here. Silly. :-) */
257
258 iph = ip_hdr(skb);
259 ihl = iph->ihl * 4;
260
261 if (x->encap) {
262 struct xfrm_encap_tmpl *encap = x->encap;
263 struct udphdr *uh = (void *)(skb_network_header(skb) + ihl);
264
265 /*
266 * 1) if the NAT-T peer's IP or port changed then
267 * advertize the change to the keying daemon.
268 * This is an inbound SA, so just compare
269 * SRC ports.
270 */
271 if (iph->saddr != x->props.saddr.a4 ||
272 uh->source != encap->encap_sport) {
273 xfrm_address_t ipaddr;
274
275 ipaddr.a4 = iph->saddr;
276 km_new_mapping(x, &ipaddr, uh->source);
277
278 /* XXX: perhaps add an extra
279 * policy check here, to see
280 * if we should allow or
281 * reject a packet from a
282 * different source
283 * address/port.
284 */
285 }
286
287 /*
288 * 2) ignore UDP/TCP checksums in case
289 * of NAT-T in Transport Mode, or
290 * perform other post-processing fixes
291 * as per draft-ietf-ipsec-udp-encaps-06,
292 * section 3.1.2
293 */
294 if (x->props.mode == XFRM_MODE_TRANSPORT)
295 skb->ip_summed = CHECKSUM_UNNECESSARY;
296 }
297
298 pskb_trim(skb, skb->len - alen - padlen - 2);
299 __skb_pull(skb, hlen);
300 skb_set_transport_header(skb, -ihl);
301
302 err = nexthdr[1];
303
304 /* RFC4303: Drop dummy packets without any error */
305 if (err == IPPROTO_NONE)
306 err = -EINVAL;
307
308 out:
309 return err;
310 }
311
312 static void esp_input_done(struct crypto_async_request *base, int err)
313 {
314 struct sk_buff *skb = base->data;
315
316 xfrm_input_resume(skb, esp_input_done2(skb, err));
317 }
318
319 /*
320 * Note: detecting truncated vs. non-truncated authentication data is very
321 * expensive, so we only support truncated data, which is the recommended
322 * and common case.
323 */
324 static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
325 {
326 struct ip_esp_hdr *esph;
327 struct esp_data *esp = x->data;
328 struct crypto_aead *aead = esp->aead;
329 struct aead_request *req;
330 struct sk_buff *trailer;
331 int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead);
332 int nfrags;
333 void *tmp;
334 u8 *iv;
335 struct scatterlist *sg;
336 struct scatterlist *asg;
337 int err = -EINVAL;
338
339 if (!pskb_may_pull(skb, sizeof(*esph)))
340 goto out;
341
342 if (elen <= 0)
343 goto out;
344
345 if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
346 goto out;
347 nfrags = err;
348
349 err = -ENOMEM;
350 tmp = esp_alloc_tmp(aead, nfrags + 1);
351 if (!tmp)
352 goto out;
353
354 ESP_SKB_CB(skb)->tmp = tmp;
355 iv = esp_tmp_iv(aead, tmp);
356 req = esp_tmp_req(aead, iv);
357 asg = esp_req_sg(aead, req);
358 sg = asg + 1;
359
360 skb->ip_summed = CHECKSUM_NONE;
361
362 esph = (struct ip_esp_hdr *)skb->data;
363
364 /* Get ivec. This can be wrong, check against another impls. */
365 iv = esph->enc_data;
366
367 sg_init_table(sg, nfrags);
368 skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen);
369 sg_init_one(asg, esph, sizeof(*esph));
370
371 aead_request_set_callback(req, 0, esp_input_done, skb);
372 aead_request_set_crypt(req, sg, sg, elen, iv);
373 aead_request_set_assoc(req, asg, sizeof(*esph));
374
375 err = crypto_aead_decrypt(req);
376 if (err == -EINPROGRESS)
377 goto out;
378
379 err = esp_input_done2(skb, err);
380
381 out:
382 return err;
383 }
384
385 static u32 esp4_get_mtu(struct xfrm_state *x, int mtu)
386 {
387 struct esp_data *esp = x->data;
388 u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4);
389 u32 align = max_t(u32, blksize, esp->padlen);
390 u32 rem;
391
392 mtu -= x->props.header_len + crypto_aead_authsize(esp->aead);
393 rem = mtu & (align - 1);
394 mtu &= ~(align - 1);
395
396 switch (x->props.mode) {
397 case XFRM_MODE_TUNNEL:
398 break;
399 default:
400 case XFRM_MODE_TRANSPORT:
401 /* The worst case */
402 mtu -= blksize - 4;
403 mtu += min_t(u32, blksize - 4, rem);
404 break;
405 case XFRM_MODE_BEET:
406 /* The worst case. */
407 mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem);
408 break;
409 }
410
411 return mtu - 2;
412 }
413
414 static void esp4_err(struct sk_buff *skb, u32 info)
415 {
416 struct iphdr *iph = (struct iphdr*)skb->data;
417 struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2));
418 struct xfrm_state *x;
419
420 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
421 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
422 return;
423
424 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET);
425 if (!x)
426 return;
427 NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
428 ntohl(esph->spi), ntohl(iph->daddr));
429 xfrm_state_put(x);
430 }
431
432 static void esp_destroy(struct xfrm_state *x)
433 {
434 struct esp_data *esp = x->data;
435
436 if (!esp)
437 return;
438
439 crypto_free_aead(esp->aead);
440 kfree(esp);
441 }
442
443 static int esp_init_aead(struct xfrm_state *x)
444 {
445 struct esp_data *esp = x->data;
446 struct crypto_aead *aead;
447 int err;
448
449 aead = crypto_alloc_aead(x->aead->alg_name, 0, 0);
450 err = PTR_ERR(aead);
451 if (IS_ERR(aead))
452 goto error;
453
454 esp->aead = aead;
455
456 err = crypto_aead_setkey(aead, x->aead->alg_key,
457 (x->aead->alg_key_len + 7) / 8);
458 if (err)
459 goto error;
460
461 err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8);
462 if (err)
463 goto error;
464
465 error:
466 return err;
467 }
468
469 static int esp_init_authenc(struct xfrm_state *x)
470 {
471 struct esp_data *esp = x->data;
472 struct crypto_aead *aead;
473 struct crypto_authenc_key_param *param;
474 struct rtattr *rta;
475 char *key;
476 char *p;
477 char authenc_name[CRYPTO_MAX_ALG_NAME];
478 unsigned int keylen;
479 int err;
480
481 err = -EINVAL;
482 if (x->ealg == NULL)
483 goto error;
484
485 err = -ENAMETOOLONG;
486 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, "authenc(%s,%s)",
487 x->aalg ? x->aalg->alg_name : "digest_null",
488 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
489 goto error;
490
491 aead = crypto_alloc_aead(authenc_name, 0, 0);
492 err = PTR_ERR(aead);
493 if (IS_ERR(aead))
494 goto error;
495
496 esp->aead = aead;
497
498 keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) +
499 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param));
500 err = -ENOMEM;
501 key = kmalloc(keylen, GFP_KERNEL);
502 if (!key)
503 goto error;
504
505 p = key;
506 rta = (void *)p;
507 rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM;
508 rta->rta_len = RTA_LENGTH(sizeof(*param));
509 param = RTA_DATA(rta);
510 p += RTA_SPACE(sizeof(*param));
511
512 if (x->aalg) {
513 struct xfrm_algo_desc *aalg_desc;
514
515 memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8);
516 p += (x->aalg->alg_key_len + 7) / 8;
517
518 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
519 BUG_ON(!aalg_desc);
520
521 err = -EINVAL;
522 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
523 crypto_aead_authsize(aead)) {
524 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
525 x->aalg->alg_name,
526 crypto_aead_authsize(aead),
527 aalg_desc->uinfo.auth.icv_fullbits/8);
528 goto free_key;
529 }
530
531 err = crypto_aead_setauthsize(
532 aead, aalg_desc->uinfo.auth.icv_truncbits / 8);
533 if (err)
534 goto free_key;
535 }
536
537 param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8);
538 memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8);
539
540 err = crypto_aead_setkey(aead, key, keylen);
541
542 free_key:
543 kfree(key);
544
545 error:
546 return err;
547 }
548
549 static int esp_init_state(struct xfrm_state *x)
550 {
551 struct esp_data *esp;
552 struct crypto_aead *aead;
553 u32 align;
554 int err;
555
556 esp = kzalloc(sizeof(*esp), GFP_KERNEL);
557 if (esp == NULL)
558 return -ENOMEM;
559
560 x->data = esp;
561
562 if (x->aead)
563 err = esp_init_aead(x);
564 else
565 err = esp_init_authenc(x);
566
567 if (err)
568 goto error;
569
570 aead = esp->aead;
571
572 esp->padlen = 0;
573
574 x->props.header_len = sizeof(struct ip_esp_hdr) +
575 crypto_aead_ivsize(aead);
576 if (x->props.mode == XFRM_MODE_TUNNEL)
577 x->props.header_len += sizeof(struct iphdr);
578 else if (x->props.mode == XFRM_MODE_BEET)
579 x->props.header_len += IPV4_BEET_PHMAXLEN;
580 if (x->encap) {
581 struct xfrm_encap_tmpl *encap = x->encap;
582
583 switch (encap->encap_type) {
584 default:
585 goto error;
586 case UDP_ENCAP_ESPINUDP:
587 x->props.header_len += sizeof(struct udphdr);
588 break;
589 case UDP_ENCAP_ESPINUDP_NON_IKE:
590 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
591 break;
592 }
593 }
594
595 align = ALIGN(crypto_aead_blocksize(aead), 4);
596 if (esp->padlen)
597 align = max_t(u32, align, esp->padlen);
598 x->props.trailer_len = align + 1 + crypto_aead_authsize(esp->aead);
599
600 error:
601 return err;
602 }
603
604 static const struct xfrm_type esp_type =
605 {
606 .description = "ESP4",
607 .owner = THIS_MODULE,
608 .proto = IPPROTO_ESP,
609 .flags = XFRM_TYPE_REPLAY_PROT,
610 .init_state = esp_init_state,
611 .destructor = esp_destroy,
612 .get_mtu = esp4_get_mtu,
613 .input = esp_input,
614 .output = esp_output
615 };
616
617 static struct net_protocol esp4_protocol = {
618 .handler = xfrm4_rcv,
619 .err_handler = esp4_err,
620 .no_policy = 1,
621 };
622
623 static int __init esp4_init(void)
624 {
625 if (xfrm_register_type(&esp_type, AF_INET) < 0) {
626 printk(KERN_INFO "ip esp init: can't add xfrm type\n");
627 return -EAGAIN;
628 }
629 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) {
630 printk(KERN_INFO "ip esp init: can't add protocol\n");
631 xfrm_unregister_type(&esp_type, AF_INET);
632 return -EAGAIN;
633 }
634 return 0;
635 }
636
637 static void __exit esp4_fini(void)
638 {
639 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0)
640 printk(KERN_INFO "ip esp close: can't remove protocol\n");
641 if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
642 printk(KERN_INFO "ip esp close: can't remove xfrm type\n");
643 }
644
645 module_init(esp4_init);
646 module_exit(esp4_fini);
647 MODULE_LICENSE("GPL");
648 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP);
WRT350N Kernel Patches