1 /* $OpenBSD: dnssec.c,v 1.28 2021/10/09 18:43:50 deraadt 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/inet.h>
30 #include <stdlib.h>
31
32 #include <openssl/rsa.h>
33
34 #ifdef LWRES
35 #include <lwres/netdb.h>
36 #include <dns/keyvalues.h>
37 #else
38 #include <netdb.h>
39 #endif
40
41 #include "dnssec.h"
42 #include "exchange.h"
43 #include "ipsec_num.h"
44 #include "libcrypto.h"
45 #include "log.h"
46 #include "message.h"
47 #include "transport.h"
48 #include "util.h"
49
50 #ifndef DNS_UFQDN_SEPARATOR
51 #define DNS_UFQDN_SEPARATOR "._ipsec."
52 #endif
53
54 /* adapted from <dns/rdatastruct.h> / RFC 2535 */
55 struct dns_rdata_key {
56 u_int16_t flags;
57 u_int8_t protocol;
58 u_int8_t algorithm;
59 u_int16_t datalen;
60 unsigned char *data;
61 };
62
63 void *
dns_get_key(int type,struct message * msg,int * keylen)64 dns_get_key(int type, struct message *msg, int *keylen)
65 {
66 struct exchange *exchange = msg->exchange;
67 struct rrsetinfo *rr;
68 struct dns_rdata_key key_rr;
69 char name[HOST_NAME_MAX+1];
70 in_addr_t ip4;
71 u_int8_t algorithm, *id, *umark;
72 size_t id_len;
73 int ret, i;
74
75 switch (type) {
76 case IKE_AUTH_RSA_SIG:
77 algorithm = DNS_KEYALG_RSA;
78 break;
79
80 case IKE_AUTH_RSA_ENC:
81 case IKE_AUTH_RSA_ENC_REV:
82 /* XXX Not yet. */
83 /* algorithm = DNS_KEYALG_RSA; */
84 return 0;
85
86 case IKE_AUTH_DSS:
87 /* XXX Not yet. */
88 /* algorithm = DNS_KEYALG_DSS; */
89 return 0;
90
91 case IKE_AUTH_PRE_SHARED:
92 default:
93 return 0;
94 }
95
96 id = exchange->initiator ? exchange->id_r : exchange->id_i;
97 id_len = exchange->initiator ? exchange->id_r_len : exchange->id_i_len;
98 bzero(name, sizeof name);
99
100 if (!id || id_len == 0) {
101 log_print("dns_get_key: ID is missing");
102 return 0;
103 }
104 /* Exchanges (and SAs) don't carry the ID in ISAKMP form */
105 id -= ISAKMP_GEN_SZ;
106 id_len += ISAKMP_GEN_SZ - ISAKMP_ID_DATA_OFF;
107
108 switch (GET_ISAKMP_ID_TYPE(id)) {
109 case IPSEC_ID_IPV4_ADDR:
110 /* We want to lookup a KEY RR in the reverse zone. */
111 if (id_len < sizeof ip4)
112 return 0;
113 memcpy(&ip4, id + ISAKMP_ID_DATA_OFF, sizeof ip4);
114 snprintf(name, sizeof name, "%d.%d.%d.%d.in-addr.arpa.", ip4
115 >> 24, (ip4 >> 16) & 0xFF, (ip4 >> 8) & 0xFF, ip4 & 0xFF);
116 break;
117
118 case IPSEC_ID_IPV6_ADDR:
119 /* XXX Not yet. */
120 return 0;
121 break;
122
123 case IPSEC_ID_FQDN:
124 if ((id_len + 1) >= sizeof name)
125 return 0;
126 /* ID is not NULL-terminated. Add trailing dot and NULL. */
127 memcpy(name, id + ISAKMP_ID_DATA_OFF, id_len);
128 *(name + id_len) = '.';
129 *(name + id_len + 1) = '\0';
130 break;
131
132 case IPSEC_ID_USER_FQDN:
133 /*
134 * Some special handling here. We want to convert the ID
135 * 'user@host.domain' string into 'user._ipsec.host.domain.'.
136 */
137 if ((id_len + sizeof(DNS_UFQDN_SEPARATOR)) >= sizeof name)
138 return 0;
139 /* Look for the '@' separator. */
140 for (umark = id + ISAKMP_ID_DATA_OFF; (umark - id) < id_len;
141 umark++)
142 if (*umark == '@')
143 break;
144 if (*umark != '@') {
145 LOG_DBG((LOG_MISC, 50, "dns_get_key: bad UFQDN ID"));
146 return 0;
147 }
148 *umark++ = '\0';
149 /* id is now terminated. 'umark', however, is not. */
150 snprintf(name, sizeof name, "%s%s", id + ISAKMP_ID_DATA_OFF,
151 DNS_UFQDN_SEPARATOR);
152 memcpy(name + strlen(name), umark, id_len - strlen(id) - 1);
153 *(name + id_len + sizeof(DNS_UFQDN_SEPARATOR) - 2) = '.';
154 *(name + id_len + sizeof(DNS_UFQDN_SEPARATOR) - 1) = '\0';
155 break;
156
157 default:
158 return 0;
159 }
160
161 LOG_DBG((LOG_MISC, 50, "dns_get_key: trying KEY RR for %s", name));
162 ret = getrrsetbyname(name, C_IN, T_KEY, 0, &rr);
163
164 if (ret) {
165 LOG_DBG((LOG_MISC, 30, "dns_get_key: no DNS responses "
166 "(error %d)", ret));
167 return 0;
168 }
169 LOG_DBG((LOG_MISC, 80,
170 "dns_get_key: rrset class %d type %d ttl %d nrdatas %d nrsigs %d",
171 rr->rri_rdclass, rr->rri_rdtype, rr->rri_ttl, rr->rri_nrdatas,
172 rr->rri_nsigs));
173
174 /* We don't accept unvalidated data. */
175 if (!(rr->rri_flags & RRSET_VALIDATED)) {
176 LOG_DBG((LOG_MISC, 10, "dns_get_key: "
177 "got unvalidated response"));
178 freerrset(rr);
179 return 0;
180 }
181 /* Sanity. */
182 if (rr->rri_nrdatas == 0 || rr->rri_rdtype != T_KEY) {
183 LOG_DBG((LOG_MISC, 30, "dns_get_key: no KEY RRs received"));
184 freerrset(rr);
185 return 0;
186 }
187 bzero(&key_rr, sizeof key_rr);
188
189 /*
190 * Find a key with the wanted algorithm, if any.
191 * XXX If there are several keys present, we currently only find the
192 * first.
193 */
194 for (i = 0; i < rr->rri_nrdatas && key_rr.datalen == 0; i++) {
195 key_rr.flags = ntohs((u_int16_t) * rr->rri_rdatas[i].rdi_data);
196 key_rr.protocol = *(rr->rri_rdatas[i].rdi_data + 2);
197 key_rr.algorithm = *(rr->rri_rdatas[i].rdi_data + 3);
198
199 if (key_rr.protocol != DNS_KEYPROTO_IPSEC) {
200 LOG_DBG((LOG_MISC, 50, "dns_get_key: ignored "
201 "non-IPsec key"));
202 continue;
203 }
204 if (key_rr.algorithm != algorithm) {
205 LOG_DBG((LOG_MISC, 50, "dns_get_key: ignored "
206 "key with other alg"));
207 continue;
208 }
209 key_rr.datalen = rr->rri_rdatas[i].rdi_length - 4;
210 if (key_rr.datalen <= 0) {
211 LOG_DBG((LOG_MISC, 50, "dns_get_key: "
212 "ignored bad key"));
213 key_rr.datalen = 0;
214 continue;
215 }
216 /* This key seems to fit our requirements... */
217 key_rr.data = malloc(key_rr.datalen);
218 if (!key_rr.data) {
219 log_error("dns_get_key: malloc (%d) failed",
220 key_rr.datalen);
221 freerrset(rr);
222 return 0;
223 }
224 memcpy(key_rr.data, rr->rri_rdatas[i].rdi_data + 4,
225 key_rr.datalen);
226 *keylen = key_rr.datalen;
227 }
228
229 freerrset(rr);
230
231 if (key_rr.datalen)
232 return key_rr.data;
233 return 0;
234 }
235
236 int
dns_RSA_dns_to_x509(u_int8_t * key,int keylen,RSA ** rsa_key)237 dns_RSA_dns_to_x509(u_int8_t *key, int keylen, RSA **rsa_key)
238 {
239 RSA *rsa;
240 int key_offset;
241 u_int8_t e_len;
242
243 if (!key || keylen <= 0) {
244 log_print("dns_RSA_dns_to_x509: invalid public key");
245 return -1;
246 }
247 rsa = RSA_new();
248 if (rsa == NULL) {
249 log_error("dns_RSA_dns_to_x509: "
250 "failed to allocate new RSA struct");
251 return -1;
252 }
253 e_len = *key;
254 key_offset = 1;
255
256 if (e_len == 0) {
257 if (keylen < 3) {
258 log_print("dns_RSA_dns_to_x509: invalid public key");
259 RSA_free(rsa);
260 return -1;
261 }
262 e_len = *(key + key_offset++) << 8;
263 e_len += *(key + key_offset++);
264 }
265 if (e_len > (keylen - key_offset)) {
266 log_print("dns_RSA_dns_to_x509: invalid public key");
267 RSA_free(rsa);
268 return -1;
269 }
270 rsa->e = BN_bin2bn(key + key_offset, e_len, NULL);
271 key_offset += e_len;
272
273 /* XXX if (keylen <= key_offset) -> "invalid public key" ? */
274
275 rsa->n = BN_bin2bn(key + key_offset, keylen - key_offset, NULL);
276
277 *rsa_key = rsa;
278
279 LOG_DBG((LOG_MISC, 30, "dns_RSA_dns_to_x509: got %d bits RSA key",
280 BN_num_bits(rsa->n)));
281 return 0;
282 }
283
284 #if notyet
285 int
dns_RSA_x509_to_dns(RSA * rsa_key,u_int8_t * key,int * keylen)286 dns_RSA_x509_to_dns(RSA *rsa_key, u_int8_t *key, int *keylen)
287 {
288 return 0;
289 }
290 #endif
291