dnssec.c revision 1.17 
1/*	$OpenBSD: dnssec.c,v 1.17 2003/11/06 16:12:07 ho Exp $	*/
2
3/*
4 * Copyright (c) 2001 H�kan Olsson.  All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/types.h>
28#include <netinet/in.h>
29#include <arpa/nameser.h>
30#include <arpa/inet.h>
31#include <stdlib.h>
32
33#include <openssl/rsa.h>
34
35#ifdef LWRES
36#include <lwres/netdb.h>
37#include <dns/keyvalues.h>
38#else
39#include <netdb.h>
40#endif
41
42#include "sysdep.h"
43
44#include "dnssec.h"
45#include "exchange.h"
46#include "ipsec_num.h"
47#include "libcrypto.h"
48#include "log.h"
49#include "message.h"
50#include "transport.h"
51#include "util.h"
52
53#ifndef DNS_UFQDN_SEPARATOR
54#define DNS_UFQDN_SEPARATOR "._ipsec."
55#endif
56
57/* adapted from <dns/rdatastruct.h> / RFC 2535  */
58struct dns_rdata_key {
59  u_int16_t flags;
60  u_int8_t protocol;
61  u_int8_t algorithm;
62  u_int16_t datalen;
63  unsigned char *data;
64};
65
66void *
67dns_get_key (int type, struct message *msg, int *keylen)
68{
69  struct exchange *exchange = msg->exchange;
70  struct rrsetinfo *rr;
71  struct dns_rdata_key key_rr;
72  char name[MAXHOSTNAMELEN];
73  in_addr_t ip4;
74  u_int8_t algorithm;
75  u_int8_t *id, *umark;
76  size_t id_len;
77  int ret, i;
78
79  switch (type)
80    {
81    case IKE_AUTH_RSA_SIG:
82      algorithm = DNS_KEYALG_RSA;
83      break;
84
85    case IKE_AUTH_RSA_ENC:
86    case IKE_AUTH_RSA_ENC_REV:
87      /* XXX Not yet. */
88      /* algorithm = DNS_KEYALG_RSA; */
89      return 0;
90
91    case IKE_AUTH_DSS:
92      /* XXX Not yet. */
93      /* algorithm = DNS_KEYALG_DSS; */
94      return 0;
95
96    case IKE_AUTH_PRE_SHARED:
97    default:
98      return 0;
99    }
100
101  id = exchange->initiator ? exchange->id_r : exchange->id_i;
102  id_len = exchange->initiator ? exchange->id_r_len : exchange->id_i_len;
103  memset (name, 0, sizeof name);
104
105  if (!id || id_len == 0)
106    {
107      log_print ("dns_get_key: ID is missing");
108      return 0;
109    }
110
111  /* Exchanges (and SAs) don't carry the ID in ISAKMP form */
112  id -= ISAKMP_GEN_SZ;
113  id_len += ISAKMP_GEN_SZ - ISAKMP_ID_DATA_OFF;
114
115  switch (GET_ISAKMP_ID_TYPE (id))
116    {
117    case IPSEC_ID_IPV4_ADDR:
118      /* We want to lookup a KEY RR in the reverse zone.  */
119      if (id_len < sizeof ip4)
120	return 0;
121      memcpy (&ip4, id + ISAKMP_ID_DATA_OFF, sizeof ip4);
122      snprintf (name, sizeof name, "%d.%d.%d.%d.in-addr.arpa.", ip4 >> 24,
123	       (ip4 >> 16) & 0xFF, (ip4 >> 8) & 0xFF, ip4 & 0xFF);
124      break;
125
126    case IPSEC_ID_IPV6_ADDR:
127      /* XXX Not yet. */
128      return 0;
129      break;
130
131    case IPSEC_ID_FQDN:
132      if ((id_len + 1) >= sizeof name)
133	return 0;
134      /* ID is not NULL-terminated. Add trailing dot and terminate.  */
135      memcpy (name, id + ISAKMP_ID_DATA_OFF, id_len);
136      *(name + id_len) = '.';
137      *(name + id_len + 1) = '\0';
138      break;
139
140    case IPSEC_ID_USER_FQDN:
141      /*
142       * Some special handling here. We want to convert the ID
143       * 'user@host.domain' string into 'user._ipsec.host.domain.'.
144       */
145      if ((id_len + sizeof (DNS_UFQDN_SEPARATOR)) >= sizeof name)
146	return 0;
147      /* Look for the '@' separator.  */
148      for (umark = id + ISAKMP_ID_DATA_OFF; (umark - id) < id_len; umark++)
149	if (*umark == '@')
150	  break;
151      if (*umark != '@')
152	{
153	  LOG_DBG ((LOG_MISC, 50, "dns_get_key: bad UFQDN ID"));
154	  return 0;
155	}
156      *umark++ = '\0';
157      /* id is now terminated. 'umark', however, is not.  */
158      snprintf (name, sizeof name, "%s%s", id + ISAKMP_ID_DATA_OFF,
159		DNS_UFQDN_SEPARATOR);
160      memcpy (name + strlen (name), umark, id_len - strlen (id) - 1);
161      *(name + id_len + sizeof (DNS_UFQDN_SEPARATOR) - 2) = '.';
162      *(name + id_len + sizeof (DNS_UFQDN_SEPARATOR) - 1) = '\0';
163      break;
164
165    default:
166      return 0;
167    }
168
169  LOG_DBG ((LOG_MISC, 50, "dns_get_key: trying KEY RR for %s", name));
170  ret = getrrsetbyname (name, C_IN, T_KEY, 0, &rr);
171
172  if (ret)
173    {
174      LOG_DBG ((LOG_MISC, 30, "dns_get_key: no DNS responses (error %d)",
175		ret));
176      return 0;
177    }
178
179  LOG_DBG ((LOG_MISC, 80,
180	    "dns_get_key: rrset class %d type %d ttl %d nrdatas %d nrsigs %d",
181	    rr->rri_rdclass, rr->rri_rdtype, rr->rri_ttl, rr->rri_nrdatas,
182	    rr->rri_nsigs));
183
184  /* We don't accept unvalidated data. */
185  if (!(rr->rri_flags & RRSET_VALIDATED))
186    {
187      LOG_DBG ((LOG_MISC, 10, "dns_get_key: got unvalidated response"));
188      freerrset (rr);
189      return 0;
190    }
191
192  /* Sanity. */
193  if (rr->rri_nrdatas == 0 || rr->rri_rdtype != T_KEY)
194    {
195      LOG_DBG ((LOG_MISC, 30, "dns_get_key: no KEY RRs received"));
196      freerrset (rr);
197      return 0;
198    }
199
200  memset (&key_rr, 0, sizeof key_rr);
201
202  /*
203   * Find a key with the wanted algorithm, if any.
204   * XXX If there are several keys present, we currently only find the first.
205   */
206  for (i = 0; i < rr->rri_nrdatas && key_rr.datalen == 0; i++)
207    {
208      key_rr.flags     = ntohs ((u_int16_t) *rr->rri_rdatas[i].rdi_data);
209      key_rr.protocol  = *(rr->rri_rdatas[i].rdi_data + 2);
210      key_rr.algorithm = *(rr->rri_rdatas[i].rdi_data + 3);
211
212      if (key_rr.protocol != DNS_KEYPROTO_IPSEC)
213	{
214	  LOG_DBG ((LOG_MISC, 50, "dns_get_key: ignored non-IPsec key"));
215	  continue;
216	}
217
218      if (key_rr.algorithm != algorithm)
219	{
220	  LOG_DBG ((LOG_MISC, 50, "dns_get_key: ignored key with other alg"));
221	  continue;
222	}
223
224      key_rr.datalen = rr->rri_rdatas[i].rdi_length - 4;
225      if (key_rr.datalen <= 0)
226	{
227	  LOG_DBG ((LOG_MISC, 50, "dns_get_key: ignored bad key"));
228	  key_rr.datalen = 0;
229	  continue;
230	}
231
232      /* This key seems to fit our requirements... */
233      key_rr.data = (char *)malloc (key_rr.datalen);
234      if (!key_rr.data)
235	{
236	  log_error ("dns_get_key: malloc (%d) failed", key_rr.datalen);
237	  freerrset (rr);
238	  return 0;
239	}
240      memcpy (key_rr.data, rr->rri_rdatas[i].rdi_data + 4, key_rr.datalen);
241      *keylen = key_rr.datalen;
242    }
243
244  freerrset (rr);
245
246  if (key_rr.datalen)
247    return key_rr.data;
248  else
249    return 0;
250}
251
252int
253dns_RSA_dns_to_x509 (u_int8_t *key, int keylen, RSA **rsa_key)
254{
255  RSA *rsa;
256  int key_offset;
257  u_int8_t e_len;
258
259  if (!key || keylen <= 0)
260    {
261      log_print ("dns_RSA_dns_to_x509: invalid public key");
262      return -1;
263    }
264
265  rsa = RSA_new ();
266  if (rsa == NULL)
267    {
268      log_error ("dns_RSA_dns_to_x509: failed to allocate new RSA struct");
269      return -1;
270    }
271
272  e_len = *key;
273  key_offset = 1;
274
275  if (e_len == 0)
276    {
277      if (keylen < 3)
278	{
279	  log_print ("dns_RSA_dns_to_x509: invalid public key");
280	  RSA_free (rsa);
281	  return -1;
282	}
283      e_len  = *(key + key_offset++) << 8;
284      e_len += *(key + key_offset++);
285    }
286
287  if (e_len > (keylen - key_offset))
288    {
289      log_print ("dns_RSA_dns_to_x509: invalid public key");
290      RSA_free (rsa);
291      return -1;
292    }
293
294  rsa->e = BN_bin2bn (key + key_offset, e_len, NULL);
295  key_offset += e_len;
296
297  /* XXX if (keylen <= key_offset) -> "invalid public key" ? */
298
299  rsa->n = BN_bin2bn (key + key_offset, keylen - key_offset, NULL);
300
301  *rsa_key = rsa;
302
303  LOG_DBG ((LOG_MISC, 30, "dns_RSA_dns_to_x509: got %d bits RSA key",
304	    BN_num_bits (rsa->n)));
305
306  return 0;
307}
308
309#if notyet
310int
311dns_RSA_x509_to_dns (RSA *rsa_key, u_int8_t *key, int *keylen)
312{
313  return 0;
314}
315#endif
316