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ipv6: Handle PMTU in ICMP error handlers.
[deliverable/linux.git] / net / ipv6 / esp6.c
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 #define pr_fmt(fmt) "IPv6: " fmt
28
29 #include <crypto/aead.h>
30 #include <crypto/authenc.h>
31 #include <linux/err.h>
32 #include <linux/module.h>
33 #include <net/ip.h>
34 #include <net/xfrm.h>
35 #include <net/esp.h>
36 #include <linux/scatterlist.h>
37 #include <linux/kernel.h>
38 #include <linux/pfkeyv2.h>
39 #include <linux/random.h>
40 #include <linux/slab.h>
41 #include <linux/spinlock.h>
42 #include <net/ip6_route.h>
43 #include <net/icmp.h>
44 #include <net/ipv6.h>
45 #include <net/protocol.h>
46 #include <linux/icmpv6.h>
47
48 struct esp_skb_cb {
49 struct xfrm_skb_cb xfrm;
50 void *tmp;
51 };
52
53 #define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0]))
54
55 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu);
56
57 /*
58 * Allocate an AEAD request structure with extra space for SG and IV.
59 *
60 * For alignment considerations the upper 32 bits of the sequence number are
61 * placed at the front, if present. Followed by the IV, the request and finally
62 * the SG list.
63 *
64 * TODO: Use spare space in skb for this where possible.
65 */
66 static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags, int seqihlen)
67 {
68 unsigned int len;
69
70 len = seqihlen;
71
72 len += crypto_aead_ivsize(aead);
73
74 if (len) {
75 len += crypto_aead_alignmask(aead) &
76 ~(crypto_tfm_ctx_alignment() - 1);
77 len = ALIGN(len, crypto_tfm_ctx_alignment());
78 }
79
80 len += sizeof(struct aead_givcrypt_request) + crypto_aead_reqsize(aead);
81 len = ALIGN(len, __alignof__(struct scatterlist));
82
83 len += sizeof(struct scatterlist) * nfrags;
84
85 return kmalloc(len, GFP_ATOMIC);
86 }
87
88 static inline __be32 *esp_tmp_seqhi(void *tmp)
89 {
90 return PTR_ALIGN((__be32 *)tmp, __alignof__(__be32));
91 }
92
93 static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp, int seqhilen)
94 {
95 return crypto_aead_ivsize(aead) ?
96 PTR_ALIGN((u8 *)tmp + seqhilen,
97 crypto_aead_alignmask(aead) + 1) : tmp + seqhilen;
98 }
99
100 static inline struct aead_givcrypt_request *esp_tmp_givreq(
101 struct crypto_aead *aead, u8 *iv)
102 {
103 struct aead_givcrypt_request *req;
104
105 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
106 crypto_tfm_ctx_alignment());
107 aead_givcrypt_set_tfm(req, aead);
108 return req;
109 }
110
111 static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv)
112 {
113 struct aead_request *req;
114
115 req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
116 crypto_tfm_ctx_alignment());
117 aead_request_set_tfm(req, aead);
118 return req;
119 }
120
121 static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead,
122 struct aead_request *req)
123 {
124 return (void *)ALIGN((unsigned long)(req + 1) +
125 crypto_aead_reqsize(aead),
126 __alignof__(struct scatterlist));
127 }
128
129 static inline struct scatterlist *esp_givreq_sg(
130 struct crypto_aead *aead, struct aead_givcrypt_request *req)
131 {
132 return (void *)ALIGN((unsigned long)(req + 1) +
133 crypto_aead_reqsize(aead),
134 __alignof__(struct scatterlist));
135 }
136
137 static void esp_output_done(struct crypto_async_request *base, int err)
138 {
139 struct sk_buff *skb = base->data;
140
141 kfree(ESP_SKB_CB(skb)->tmp);
142 xfrm_output_resume(skb, err);
143 }
144
145 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
146 {
147 int err;
148 struct ip_esp_hdr *esph;
149 struct crypto_aead *aead;
150 struct aead_givcrypt_request *req;
151 struct scatterlist *sg;
152 struct scatterlist *asg;
153 struct sk_buff *trailer;
154 void *tmp;
155 int blksize;
156 int clen;
157 int alen;
158 int plen;
159 int tfclen;
160 int nfrags;
161 int assoclen;
162 int sglists;
163 int seqhilen;
164 u8 *iv;
165 u8 *tail;
166 __be32 *seqhi;
167 struct esp_data *esp = x->data;
168
169 /* skb is pure payload to encrypt */
170 err = -ENOMEM;
171
172 aead = esp->aead;
173 alen = crypto_aead_authsize(aead);
174
175 tfclen = 0;
176 if (x->tfcpad) {
177 struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb);
178 u32 padto;
179
180 padto = min(x->tfcpad, esp6_get_mtu(x, dst->child_mtu_cached));
181 if (skb->len < padto)
182 tfclen = padto - skb->len;
183 }
184 blksize = ALIGN(crypto_aead_blocksize(aead), 4);
185 clen = ALIGN(skb->len + 2 + tfclen, blksize);
186 if (esp->padlen)
187 clen = ALIGN(clen, esp->padlen);
188 plen = clen - skb->len - tfclen;
189
190 err = skb_cow_data(skb, tfclen + plen + alen, &trailer);
191 if (err < 0)
192 goto error;
193 nfrags = err;
194
195 assoclen = sizeof(*esph);
196 sglists = 1;
197 seqhilen = 0;
198
199 if (x->props.flags & XFRM_STATE_ESN) {
200 sglists += 2;
201 seqhilen += sizeof(__be32);
202 assoclen += seqhilen;
203 }
204
205 tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen);
206 if (!tmp)
207 goto error;
208
209 seqhi = esp_tmp_seqhi(tmp);
210 iv = esp_tmp_iv(aead, tmp, seqhilen);
211 req = esp_tmp_givreq(aead, iv);
212 asg = esp_givreq_sg(aead, req);
213 sg = asg + sglists;
214
215 /* Fill padding... */
216 tail = skb_tail_pointer(trailer);
217 if (tfclen) {
218 memset(tail, 0, tfclen);
219 tail += tfclen;
220 }
221 do {
222 int i;
223 for (i = 0; i < plen - 2; i++)
224 tail[i] = i + 1;
225 } while (0);
226 tail[plen - 2] = plen - 2;
227 tail[plen - 1] = *skb_mac_header(skb);
228 pskb_put(skb, trailer, clen - skb->len + alen);
229
230 skb_push(skb, -skb_network_offset(skb));
231 esph = ip_esp_hdr(skb);
232 *skb_mac_header(skb) = IPPROTO_ESP;
233
234 esph->spi = x->id.spi;
235 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
236
237 sg_init_table(sg, nfrags);
238 skb_to_sgvec(skb, sg,
239 esph->enc_data + crypto_aead_ivsize(aead) - skb->data,
240 clen + alen);
241
242 if ((x->props.flags & XFRM_STATE_ESN)) {
243 sg_init_table(asg, 3);
244 sg_set_buf(asg, &esph->spi, sizeof(__be32));
245 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
246 sg_set_buf(asg + 1, seqhi, seqhilen);
247 sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32));
248 } else
249 sg_init_one(asg, esph, sizeof(*esph));
250
251 aead_givcrypt_set_callback(req, 0, esp_output_done, skb);
252 aead_givcrypt_set_crypt(req, sg, sg, clen, iv);
253 aead_givcrypt_set_assoc(req, asg, assoclen);
254 aead_givcrypt_set_giv(req, esph->enc_data,
255 XFRM_SKB_CB(skb)->seq.output.low);
256
257 ESP_SKB_CB(skb)->tmp = tmp;
258 err = crypto_aead_givencrypt(req);
259 if (err == -EINPROGRESS)
260 goto error;
261
262 if (err == -EBUSY)
263 err = NET_XMIT_DROP;
264
265 kfree(tmp);
266
267 error:
268 return err;
269 }
270
271 static int esp_input_done2(struct sk_buff *skb, int err)
272 {
273 struct xfrm_state *x = xfrm_input_state(skb);
274 struct esp_data *esp = x->data;
275 struct crypto_aead *aead = esp->aead;
276 int alen = crypto_aead_authsize(aead);
277 int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
278 int elen = skb->len - hlen;
279 int hdr_len = skb_network_header_len(skb);
280 int padlen;
281 u8 nexthdr[2];
282
283 kfree(ESP_SKB_CB(skb)->tmp);
284
285 if (unlikely(err))
286 goto out;
287
288 if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2))
289 BUG();
290
291 err = -EINVAL;
292 padlen = nexthdr[0];
293 if (padlen + 2 + alen >= elen) {
294 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage "
295 "padlen=%d, elen=%d\n", padlen + 2, elen - alen);
296 goto out;
297 }
298
299 /* ... check padding bits here. Silly. :-) */
300
301 pskb_trim(skb, skb->len - alen - padlen - 2);
302 __skb_pull(skb, hlen);
303 skb_set_transport_header(skb, -hdr_len);
304
305 err = nexthdr[1];
306
307 /* RFC4303: Drop dummy packets without any error */
308 if (err == IPPROTO_NONE)
309 err = -EINVAL;
310
311 out:
312 return err;
313 }
314
315 static void esp_input_done(struct crypto_async_request *base, int err)
316 {
317 struct sk_buff *skb = base->data;
318
319 xfrm_input_resume(skb, esp_input_done2(skb, err));
320 }
321
322 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
323 {
324 struct ip_esp_hdr *esph;
325 struct esp_data *esp = x->data;
326 struct crypto_aead *aead = esp->aead;
327 struct aead_request *req;
328 struct sk_buff *trailer;
329 int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead);
330 int nfrags;
331 int assoclen;
332 int sglists;
333 int seqhilen;
334 int ret = 0;
335 void *tmp;
336 __be32 *seqhi;
337 u8 *iv;
338 struct scatterlist *sg;
339 struct scatterlist *asg;
340
341 if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead))) {
342 ret = -EINVAL;
343 goto out;
344 }
345
346 if (elen <= 0) {
347 ret = -EINVAL;
348 goto out;
349 }
350
351 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
352 ret = -EINVAL;
353 goto out;
354 }
355
356 ret = -ENOMEM;
357
358 assoclen = sizeof(*esph);
359 sglists = 1;
360 seqhilen = 0;
361
362 if (x->props.flags & XFRM_STATE_ESN) {
363 sglists += 2;
364 seqhilen += sizeof(__be32);
365 assoclen += seqhilen;
366 }
367
368 tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen);
369 if (!tmp)
370 goto out;
371
372 ESP_SKB_CB(skb)->tmp = tmp;
373 seqhi = esp_tmp_seqhi(tmp);
374 iv = esp_tmp_iv(aead, tmp, seqhilen);
375 req = esp_tmp_req(aead, iv);
376 asg = esp_req_sg(aead, req);
377 sg = asg + sglists;
378
379 skb->ip_summed = CHECKSUM_NONE;
380
381 esph = (struct ip_esp_hdr *)skb->data;
382
383 /* Get ivec. This can be wrong, check against another impls. */
384 iv = esph->enc_data;
385
386 sg_init_table(sg, nfrags);
387 skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen);
388
389 if ((x->props.flags & XFRM_STATE_ESN)) {
390 sg_init_table(asg, 3);
391 sg_set_buf(asg, &esph->spi, sizeof(__be32));
392 *seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
393 sg_set_buf(asg + 1, seqhi, seqhilen);
394 sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32));
395 } else
396 sg_init_one(asg, esph, sizeof(*esph));
397
398 aead_request_set_callback(req, 0, esp_input_done, skb);
399 aead_request_set_crypt(req, sg, sg, elen, iv);
400 aead_request_set_assoc(req, asg, assoclen);
401
402 ret = crypto_aead_decrypt(req);
403 if (ret == -EINPROGRESS)
404 goto out;
405
406 ret = esp_input_done2(skb, ret);
407
408 out:
409 return ret;
410 }
411
412 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu)
413 {
414 struct esp_data *esp = x->data;
415 u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4);
416 u32 align = max_t(u32, blksize, esp->padlen);
417 unsigned int net_adj;
418
419 if (x->props.mode != XFRM_MODE_TUNNEL)
420 net_adj = sizeof(struct ipv6hdr);
421 else
422 net_adj = 0;
423
424 return ((mtu - x->props.header_len - crypto_aead_authsize(esp->aead) -
425 net_adj) & ~(align - 1)) + (net_adj - 2);
426 }
427
428 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
429 u8 type, u8 code, int offset, __be32 info)
430 {
431 struct net *net = dev_net(skb->dev);
432 const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data;
433 struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset);
434 struct xfrm_state *x;
435
436 if (type != ICMPV6_DEST_UNREACH &&
437 type != ICMPV6_PKT_TOOBIG)
438 return;
439
440 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
441 esph->spi, IPPROTO_ESP, AF_INET6);
442 if (!x)
443 return;
444 pr_debug("pmtu discovery on SA ESP/%08x/%pI6\n",
445 ntohl(esph->spi), &iph->daddr);
446 ip6_update_pmtu(skb, net, info, 0, 0);
447 xfrm_state_put(x);
448 }
449
450 static void esp6_destroy(struct xfrm_state *x)
451 {
452 struct esp_data *esp = x->data;
453
454 if (!esp)
455 return;
456
457 crypto_free_aead(esp->aead);
458 kfree(esp);
459 }
460
461 static int esp_init_aead(struct xfrm_state *x)
462 {
463 struct esp_data *esp = x->data;
464 struct crypto_aead *aead;
465 int err;
466
467 aead = crypto_alloc_aead(x->aead->alg_name, 0, 0);
468 err = PTR_ERR(aead);
469 if (IS_ERR(aead))
470 goto error;
471
472 esp->aead = aead;
473
474 err = crypto_aead_setkey(aead, x->aead->alg_key,
475 (x->aead->alg_key_len + 7) / 8);
476 if (err)
477 goto error;
478
479 err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8);
480 if (err)
481 goto error;
482
483 error:
484 return err;
485 }
486
487 static int esp_init_authenc(struct xfrm_state *x)
488 {
489 struct esp_data *esp = x->data;
490 struct crypto_aead *aead;
491 struct crypto_authenc_key_param *param;
492 struct rtattr *rta;
493 char *key;
494 char *p;
495 char authenc_name[CRYPTO_MAX_ALG_NAME];
496 unsigned int keylen;
497 int err;
498
499 err = -EINVAL;
500 if (x->ealg == NULL)
501 goto error;
502
503 err = -ENAMETOOLONG;
504
505 if ((x->props.flags & XFRM_STATE_ESN)) {
506 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
507 "authencesn(%s,%s)",
508 x->aalg ? x->aalg->alg_name : "digest_null",
509 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
510 goto error;
511 } else {
512 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
513 "authenc(%s,%s)",
514 x->aalg ? x->aalg->alg_name : "digest_null",
515 x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
516 goto error;
517 }
518
519 aead = crypto_alloc_aead(authenc_name, 0, 0);
520 err = PTR_ERR(aead);
521 if (IS_ERR(aead))
522 goto error;
523
524 esp->aead = aead;
525
526 keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) +
527 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param));
528 err = -ENOMEM;
529 key = kmalloc(keylen, GFP_KERNEL);
530 if (!key)
531 goto error;
532
533 p = key;
534 rta = (void *)p;
535 rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM;
536 rta->rta_len = RTA_LENGTH(sizeof(*param));
537 param = RTA_DATA(rta);
538 p += RTA_SPACE(sizeof(*param));
539
540 if (x->aalg) {
541 struct xfrm_algo_desc *aalg_desc;
542
543 memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8);
544 p += (x->aalg->alg_key_len + 7) / 8;
545
546 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
547 BUG_ON(!aalg_desc);
548
549 err = -EINVAL;
550 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
551 crypto_aead_authsize(aead)) {
552 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
553 x->aalg->alg_name,
554 crypto_aead_authsize(aead),
555 aalg_desc->uinfo.auth.icv_fullbits/8);
556 goto free_key;
557 }
558
559 err = crypto_aead_setauthsize(
560 aead, x->aalg->alg_trunc_len / 8);
561 if (err)
562 goto free_key;
563 }
564
565 param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8);
566 memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8);
567
568 err = crypto_aead_setkey(aead, key, keylen);
569
570 free_key:
571 kfree(key);
572
573 error:
574 return err;
575 }
576
577 static int esp6_init_state(struct xfrm_state *x)
578 {
579 struct esp_data *esp;
580 struct crypto_aead *aead;
581 u32 align;
582 int err;
583
584 if (x->encap)
585 return -EINVAL;
586
587 esp = kzalloc(sizeof(*esp), GFP_KERNEL);
588 if (esp == NULL)
589 return -ENOMEM;
590
591 x->data = esp;
592
593 if (x->aead)
594 err = esp_init_aead(x);
595 else
596 err = esp_init_authenc(x);
597
598 if (err)
599 goto error;
600
601 aead = esp->aead;
602
603 esp->padlen = 0;
604
605 x->props.header_len = sizeof(struct ip_esp_hdr) +
606 crypto_aead_ivsize(aead);
607 switch (x->props.mode) {
608 case XFRM_MODE_BEET:
609 if (x->sel.family != AF_INET6)
610 x->props.header_len += IPV4_BEET_PHMAXLEN +
611 (sizeof(struct ipv6hdr) - sizeof(struct iphdr));
612 break;
613 case XFRM_MODE_TRANSPORT:
614 break;
615 case XFRM_MODE_TUNNEL:
616 x->props.header_len += sizeof(struct ipv6hdr);
617 break;
618 default:
619 goto error;
620 }
621
622 align = ALIGN(crypto_aead_blocksize(aead), 4);
623 if (esp->padlen)
624 align = max_t(u32, align, esp->padlen);
625 x->props.trailer_len = align + 1 + crypto_aead_authsize(esp->aead);
626
627 error:
628 return err;
629 }
630
631 static const struct xfrm_type esp6_type =
632 {
633 .description = "ESP6",
634 .owner = THIS_MODULE,
635 .proto = IPPROTO_ESP,
636 .flags = XFRM_TYPE_REPLAY_PROT,
637 .init_state = esp6_init_state,
638 .destructor = esp6_destroy,
639 .get_mtu = esp6_get_mtu,
640 .input = esp6_input,
641 .output = esp6_output,
642 .hdr_offset = xfrm6_find_1stfragopt,
643 };
644
645 static const struct inet6_protocol esp6_protocol = {
646 .handler = xfrm6_rcv,
647 .err_handler = esp6_err,
648 .flags = INET6_PROTO_NOPOLICY,
649 };
650
651 static int __init esp6_init(void)
652 {
653 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
654 pr_info("%s: can't add xfrm type\n", __func__);
655 return -EAGAIN;
656 }
657 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
658 pr_info("%s: can't add protocol\n", __func__);
659 xfrm_unregister_type(&esp6_type, AF_INET6);
660 return -EAGAIN;
661 }
662
663 return 0;
664 }
665
666 static void __exit esp6_fini(void)
667 {
668 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
669 pr_info("%s: can't remove protocol\n", __func__);
670 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
671 pr_info("%s: can't remove xfrm type\n", __func__);
672 }
673
674 module_init(esp6_init);
675 module_exit(esp6_fini);
676
677 MODULE_LICENSE("GPL");
678 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP);
Linux kernel - Deliverables
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