dnssec.c revision 1.14 
1/*	$OpenBSD: dnssec.c,v 1.14 2002/06/10 18:08:58 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 * 3. The name of the author may not be used to endorse or promote products
15 *    derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <sys/types.h>
30#include <netinet/in.h>
31#include <arpa/nameser.h>
32#include <arpa/inet.h>
33#include <stdlib.h>
34
35#include <openssl/rsa.h>
36
37#ifdef LWRES
38#include <lwres/netdb.h>
39#include <dns/keyvalues.h>
40#else
41#include <netdb.h>
42#endif
43
44#include "sysdep.h"
45
46#include "dnssec.h"
47#include "exchange.h"
48#include "ipsec_num.h"
49#include "libcrypto.h"
50#include "log.h"
51#include "message.h"
52#include "transport.h"
53#include "util.h"
54
55#ifndef DNS_UFQDN_SEPARATOR
56#define DNS_UFQDN_SEPARATOR "._ipsec."
57#endif
58
59/* adapted from <dns/rdatastruct.h> / RFC 2535  */
60struct dns_rdata_key {
61  u_int16_t flags;
62  u_int8_t protocol;
63  u_int8_t algorithm;
64  u_int16_t datalen;
65  unsigned char *data;
66};
67
68void *
69dns_get_key (int type, struct message *msg, int *keylen)
70{
71  struct exchange *exchange = msg->exchange;
72  struct rrsetinfo *rr;
73  struct dns_rdata_key key_rr;
74  char name[MAXHOSTNAMELEN];
75  in_addr_t ip4;
76  u_int8_t algorithm;
77  u_int8_t *id, *umark;
78  size_t id_len;
79  int ret, i;
80
81  switch (type)
82    {
83    case IKE_AUTH_RSA_SIG:
84      algorithm = DNS_KEYALG_RSA;
85      break;
86
87    case IKE_AUTH_RSA_ENC:
88    case IKE_AUTH_RSA_ENC_REV:
89      /* XXX Not yet. */
90      /* algorithm = DNS_KEYALG_RSA; */
91      return 0;
92
93    case IKE_AUTH_DSS:
94      /* XXX Not yet. */
95      /* algorithm = DNS_KEYALG_DSS; */
96      return 0;
97
98    case IKE_AUTH_PRE_SHARED:
99    default:
100      return 0;
101    }
102
103  id = exchange->initiator ? exchange->id_r : exchange->id_i;
104  id_len = exchange->initiator ? exchange->id_r_len : exchange->id_i_len;
105  memset (name, 0, MAXHOSTNAMELEN);
106
107  if (!id || id_len == 0)
108    {
109      log_print ("dns_get_key: ID is missing");
110      return 0;
111    }
112
113  /* Exchanges (and SAs) don't carry the ID in ISAKMP form */
114  id -= ISAKMP_GEN_SZ;
115  id_len += ISAKMP_GEN_SZ - ISAKMP_ID_DATA_OFF;
116
117  switch (GET_ISAKMP_ID_TYPE (id))
118    {
119    case IPSEC_ID_IPV4_ADDR:
120      /* We want to lookup a KEY RR in the reverse zone.  */
121      if (id_len < sizeof ip4)
122	return 0;
123      memcpy (&ip4, id + ISAKMP_ID_DATA_OFF, sizeof ip4);
124      snprintf (name, MAXHOSTNAMELEN, "%d.%d.%d.%d.in-addr.arpa.", ip4 >> 24,
125	       (ip4 >> 16) & 0xFF, (ip4 >> 8) & 0xFF, ip4 & 0xFF);
126      break;
127
128    case IPSEC_ID_IPV6_ADDR:
129      /* XXX Not yet. */
130      return 0;
131      break;
132
133    case IPSEC_ID_FQDN:
134      if ((id_len + 1) >= MAXHOSTNAMELEN)
135	return 0;
136      /* ID is not NULL-terminated. Add trailing dot and terminate.  */
137      memcpy (name, id + ISAKMP_ID_DATA_OFF, id_len);
138      *(name + id_len) = '.';
139      *(name + id_len + 1) = '\0';
140      break;
141
142    case IPSEC_ID_USER_FQDN:
143      /*
144       * Some special handling here. We want to convert the ID
145       * 'user@host.domain' string into 'user._ipsec.host.domain.'.
146       */
147      if ((id_len + sizeof (DNS_UFQDN_SEPARATOR)) >= MAXHOSTNAMELEN)
148	return 0;
149      /* Look for the '@' separator.  */
150      for (umark = id + ISAKMP_ID_DATA_OFF; (umark - id) < id_len; umark++)
151	if (*umark == '@')
152	  break;
153      if (*umark != '@')
154	{
155	  LOG_DBG((LOG_MISC, 50, "dns_get_key: bad UFQDN ID"));
156	  return 0;
157	}
158      *umark++ = '\0';
159      /* id is now terminated. 'umark', however, is not.  */
160      snprintf (name, MAXHOSTNAMELEN, "%s%s", id + ISAKMP_ID_DATA_OFF,
161		DNS_UFQDN_SEPARATOR);
162      memcpy (name + strlen (name), umark, id_len - strlen (id) - 1);
163      *(name + id_len + sizeof (DNS_UFQDN_SEPARATOR) - 2) = '.';
164      *(name + id_len + sizeof (DNS_UFQDN_SEPARATOR) - 1) = '\0';
165      break;
166
167    default:
168      return 0;
169    }
170
171  LOG_DBG ((LOG_MISC, 50, "dns_get_key: trying KEY RR for %s", name));
172  ret = getrrsetbyname (name, C_IN, T_KEY, 0, &rr);
173
174  if (ret)
175    {
176      LOG_DBG ((LOG_MISC, 30, "dns_get_key: no DNS responses (error %d)",
177		ret));
178      return 0;
179    }
180
181  LOG_DBG ((LOG_MISC, 80,
182	    "dns_get_key: rrset class %d type %d ttl %d nrdatas %d nrsigs %d",
183	    rr->rri_rdclass, rr->rri_rdtype, rr->rri_ttl, rr->rri_nrdatas,
184	    rr->rri_nsigs));
185
186  /* We don't accept unvalidated data. */
187  if (!(rr->rri_flags & RRSET_VALIDATED))
188    {
189      LOG_DBG ((LOG_MISC, 10, "dns_get_key: got unvalidated response"));
190      freerrset (rr);
191      return 0;
192    }
193
194  /* Sanity. */
195  if (rr->rri_nrdatas == 0 || rr->rri_rdtype != T_KEY)
196    {
197      LOG_DBG ((LOG_MISC, 30, "dns_get_key: no KEY RRs received"));
198      freerrset (rr);
199      return 0;
200    }
201
202  memset (&key_rr, 0, sizeof key_rr);
203
204  /*
205   * Find a key with the wanted algorithm, if any.
206   * XXX If there are several keys present, we currently only find the first.
207   */
208  for (i = 0; i < rr->rri_nrdatas && key_rr.datalen == 0; i++)
209    {
210      key_rr.flags     = ntohs ((u_int16_t) *rr->rri_rdatas[i].rdi_data);
211      key_rr.protocol  = *(rr->rri_rdatas[i].rdi_data + 2);
212      key_rr.algorithm = *(rr->rri_rdatas[i].rdi_data + 3);
213
214      if (key_rr.protocol != DNS_KEYPROTO_IPSEC)
215	{
216	  LOG_DBG ((LOG_MISC, 50, "dns_get_key: ignored non-IPsec key"));
217	  continue;
218	}
219
220      if (key_rr.algorithm != algorithm)
221	{
222	  LOG_DBG ((LOG_MISC, 50, "dns_get_key: ignored key with other alg"));
223	  continue;
224	}
225
226      key_rr.datalen = rr->rri_rdatas[i].rdi_length - 4;
227      if (key_rr.datalen <= 0)
228	{
229	  LOG_DBG ((LOG_MISC, 50, "dns_get_key: ignored bad key"));
230	  key_rr.datalen = 0;
231	  continue;
232	}
233
234      /* This key seems to fit our requirements... */
235      key_rr.data = (char *)malloc (key_rr.datalen);
236      if (!key_rr.data)
237	{
238	  log_error ("dns_get_key: malloc (%d) failed", key_rr.datalen);
239	  freerrset (rr);
240	  return 0;
241	}
242      memcpy (key_rr.data, rr->rri_rdatas[i].rdi_data + 4, key_rr.datalen);
243      *keylen = key_rr.datalen;
244    }
245
246  freerrset (rr);
247
248  if (key_rr.datalen)
249    return key_rr.data;
250  else
251    return 0;
252}
253
254int
255dns_RSA_dns_to_x509 (u_int8_t *key, int keylen, RSA **rsa_key)
256{
257  RSA *rsa;
258  int key_offset;
259  u_int8_t e_len;
260
261  if (!key || keylen <= 0)
262    {
263      log_print ("dns_RSA_dns_to_x509: invalid public key");
264      return -1;
265    }
266
267  rsa = RSA_new ();
268  if (rsa == NULL)
269    {
270      log_error ("dns_RSA_dns_to_x509: failed to allocate new RSA struct");
271      return -1;
272    }
273
274  e_len = *key;
275  key_offset = 1;
276
277  if (e_len == 0)
278    {
279      if (keylen < 3)
280	{
281	  log_print ("dns_RSA_dns_to_x509: invalid public key");
282	  RSA_free (rsa);
283	  return -1;
284	}
285      e_len  = *(key + key_offset++) << 8;
286      e_len += *(key + key_offset++);
287    }
288
289  if (e_len > (keylen - key_offset))
290    {
291      log_print ("dns_RSA_dns_to_x509: invalid public key");
292      RSA_free (rsa);
293      return -1;
294    }
295
296  rsa->e = BN_bin2bn (key + key_offset, e_len, NULL);
297  key_offset += e_len;
298
299  /* XXX if (keylen <= key_offset) -> "invalid public key" ? */
300
301  rsa->n = BN_bin2bn (key + key_offset, keylen - key_offset, NULL);
302
303  *rsa_key = rsa;
304
305  LOG_DBG ((LOG_MISC, 30, "dns_RSA_dns_to_x509: got %d bits RSA key",
306	    BN_num_bits (rsa->n)));
307
308  return 0;
309}
310
311#if notyet
312int
313dns_RSA_x509_to_dns (RSA *rsa_key, u_int8_t *key, int *keylen)
314{
315  return 0;
316}
317#endif
318