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esp6.c
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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 <[email protected]>
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  aead = esp->aead;
171  alen = crypto_aead_authsize(aead);
172 
173  tfclen = 0;
174  if (x->tfcpad) {
175  struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb);
176  u32 padto;
177 
178  padto = min(x->tfcpad, esp6_get_mtu(x, dst->child_mtu_cached));
179  if (skb->len < padto)
180  tfclen = padto - skb->len;
181  }
182  blksize = ALIGN(crypto_aead_blocksize(aead), 4);
183  clen = ALIGN(skb->len + 2 + tfclen, blksize);
184  if (esp->padlen)
185  clen = ALIGN(clen, esp->padlen);
186  plen = clen - skb->len - tfclen;
187 
188  err = skb_cow_data(skb, tfclen + plen + alen, &trailer);
189  if (err < 0)
190  goto error;
191  nfrags = err;
192 
193  assoclen = sizeof(*esph);
194  sglists = 1;
195  seqhilen = 0;
196 
197  if (x->props.flags & XFRM_STATE_ESN) {
198  sglists += 2;
199  seqhilen += sizeof(__be32);
200  assoclen += seqhilen;
201  }
202 
203  tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen);
204  if (!tmp) {
205  err = -ENOMEM;
206  goto error;
207  }
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  type != NDISC_REDIRECT)
439  return;
440 
441  x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
442  esph->spi, IPPROTO_ESP, AF_INET6);
443  if (!x)
444  return;
445 
446  if (type == NDISC_REDIRECT)
447  ip6_redirect(skb, net, 0, 0);
448  else
449  ip6_update_pmtu(skb, net, info, 0, 0);
450  xfrm_state_put(x);
451 }
452 
453 static void esp6_destroy(struct xfrm_state *x)
454 {
455  struct esp_data *esp = x->data;
456 
457  if (!esp)
458  return;
459 
460  crypto_free_aead(esp->aead);
461  kfree(esp);
462 }
463 
464 static int esp_init_aead(struct xfrm_state *x)
465 {
466  struct esp_data *esp = x->data;
467  struct crypto_aead *aead;
468  int err;
469 
470  aead = crypto_alloc_aead(x->aead->alg_name, 0, 0);
471  err = PTR_ERR(aead);
472  if (IS_ERR(aead))
473  goto error;
474 
475  esp->aead = aead;
476 
477  err = crypto_aead_setkey(aead, x->aead->alg_key,
478  (x->aead->alg_key_len + 7) / 8);
479  if (err)
480  goto error;
481 
482  err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8);
483  if (err)
484  goto error;
485 
486 error:
487  return err;
488 }
489 
490 static int esp_init_authenc(struct xfrm_state *x)
491 {
492  struct esp_data *esp = x->data;
493  struct crypto_aead *aead;
495  struct rtattr *rta;
496  char *key;
497  char *p;
498  char authenc_name[CRYPTO_MAX_ALG_NAME];
499  unsigned int keylen;
500  int err;
501 
502  err = -EINVAL;
503  if (x->ealg == NULL)
504  goto error;
505 
506  err = -ENAMETOOLONG;
507 
508  if ((x->props.flags & XFRM_STATE_ESN)) {
509  if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
510  "authencesn(%s,%s)",
511  x->aalg ? x->aalg->alg_name : "digest_null",
512  x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
513  goto error;
514  } else {
515  if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
516  "authenc(%s,%s)",
517  x->aalg ? x->aalg->alg_name : "digest_null",
518  x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
519  goto error;
520  }
521 
522  aead = crypto_alloc_aead(authenc_name, 0, 0);
523  err = PTR_ERR(aead);
524  if (IS_ERR(aead))
525  goto error;
526 
527  esp->aead = aead;
528 
529  keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) +
530  (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param));
531  err = -ENOMEM;
532  key = kmalloc(keylen, GFP_KERNEL);
533  if (!key)
534  goto error;
535 
536  p = key;
537  rta = (void *)p;
539  rta->rta_len = RTA_LENGTH(sizeof(*param));
540  param = RTA_DATA(rta);
541  p += RTA_SPACE(sizeof(*param));
542 
543  if (x->aalg) {
544  struct xfrm_algo_desc *aalg_desc;
545 
546  memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8);
547  p += (x->aalg->alg_key_len + 7) / 8;
548 
549  aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
550  BUG_ON(!aalg_desc);
551 
552  err = -EINVAL;
553  if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
554  crypto_aead_authsize(aead)) {
555  NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
556  x->aalg->alg_name,
557  crypto_aead_authsize(aead),
558  aalg_desc->uinfo.auth.icv_fullbits/8);
559  goto free_key;
560  }
561 
563  aead, x->aalg->alg_trunc_len / 8);
564  if (err)
565  goto free_key;
566  }
567 
568  param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8);
569  memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8);
570 
571  err = crypto_aead_setkey(aead, key, keylen);
572 
573 free_key:
574  kfree(key);
575 
576 error:
577  return err;
578 }
579 
580 static int esp6_init_state(struct xfrm_state *x)
581 {
582  struct esp_data *esp;
583  struct crypto_aead *aead;
584  u32 align;
585  int err;
586 
587  if (x->encap)
588  return -EINVAL;
589 
590  esp = kzalloc(sizeof(*esp), GFP_KERNEL);
591  if (esp == NULL)
592  return -ENOMEM;
593 
594  x->data = esp;
595 
596  if (x->aead)
597  err = esp_init_aead(x);
598  else
599  err = esp_init_authenc(x);
600 
601  if (err)
602  goto error;
603 
604  aead = esp->aead;
605 
606  esp->padlen = 0;
607 
608  x->props.header_len = sizeof(struct ip_esp_hdr) +
609  crypto_aead_ivsize(aead);
610  switch (x->props.mode) {
611  case XFRM_MODE_BEET:
612  if (x->sel.family != AF_INET6)
613  x->props.header_len += IPV4_BEET_PHMAXLEN +
614  (sizeof(struct ipv6hdr) - sizeof(struct iphdr));
615  break;
616  case XFRM_MODE_TRANSPORT:
617  break;
618  case XFRM_MODE_TUNNEL:
619  x->props.header_len += sizeof(struct ipv6hdr);
620  break;
621  default:
622  goto error;
623  }
624 
625  align = ALIGN(crypto_aead_blocksize(aead), 4);
626  if (esp->padlen)
627  align = max_t(u32, align, esp->padlen);
628  x->props.trailer_len = align + 1 + crypto_aead_authsize(esp->aead);
629 
630 error:
631  return err;
632 }
633 
634 static const struct xfrm_type esp6_type =
635 {
636  .description = "ESP6",
637  .owner = THIS_MODULE,
638  .proto = IPPROTO_ESP,
639  .flags = XFRM_TYPE_REPLAY_PROT,
640  .init_state = esp6_init_state,
641  .destructor = esp6_destroy,
642  .get_mtu = esp6_get_mtu,
643  .input = esp6_input,
644  .output = esp6_output,
645  .hdr_offset = xfrm6_find_1stfragopt,
646 };
647 
648 static const struct inet6_protocol esp6_protocol = {
649  .handler = xfrm6_rcv,
650  .err_handler = esp6_err,
651  .flags = INET6_PROTO_NOPOLICY,
652 };
653 
654 static int __init esp6_init(void)
655 {
656  if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
657  pr_info("%s: can't add xfrm type\n", __func__);
658  return -EAGAIN;
659  }
660  if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
661  pr_info("%s: can't add protocol\n", __func__);
662  xfrm_unregister_type(&esp6_type, AF_INET6);
663  return -EAGAIN;
664  }
665 
666  return 0;
667 }
668 
669 static void __exit esp6_fini(void)
670 {
671  if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
672  pr_info("%s: can't remove protocol\n", __func__);
673  if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
674  pr_info("%s: can't remove xfrm type\n", __func__);
675 }
676 
677 module_init(esp6_init);
678 module_exit(esp6_fini);
679 
680 MODULE_LICENSE("GPL");