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/* $OpenBSD: dnssec.c,v 1.19 2004/05/14 08:42:56 hshoexer Exp $ */
/*
* Copyright (c) 2001 Håkan Olsson. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <openssl/rsa.h>
#ifdef LWRES
#include <lwres/netdb.h>
#include <dns/keyvalues.h>
#else
#include <netdb.h>
#endif
#include "sysdep.h"
#include "dnssec.h"
#include "exchange.h"
#include "ipsec_num.h"
#include "libcrypto.h"
#include "log.h"
#include "message.h"
#include "transport.h"
#include "util.h"
#ifndef DNS_UFQDN_SEPARATOR
#define DNS_UFQDN_SEPARATOR "._ipsec."
#endif
/* adapted from <dns/rdatastruct.h> / RFC 2535 */
struct dns_rdata_key {
u_int16_t flags;
u_int8_t protocol;
u_int8_t algorithm;
u_int16_t datalen;
unsigned char *data;
};
void *
dns_get_key(int type, struct message *msg, int *keylen)
{
struct exchange *exchange = msg->exchange;
struct rrsetinfo *rr;
struct dns_rdata_key key_rr;
char name[MAXHOSTNAMELEN];
in_addr_t ip4;
u_int8_t algorithm, *id, *umark;
size_t id_len;
int ret, i;
switch (type) {
case IKE_AUTH_RSA_SIG:
algorithm = DNS_KEYALG_RSA;
break;
case IKE_AUTH_RSA_ENC:
case IKE_AUTH_RSA_ENC_REV:
/* XXX Not yet. */
/* algorithm = DNS_KEYALG_RSA; */
return 0;
case IKE_AUTH_DSS:
/* XXX Not yet. */
/* algorithm = DNS_KEYALG_DSS; */
return 0;
case IKE_AUTH_PRE_SHARED:
default:
return 0;
}
id = exchange->initiator ? exchange->id_r : exchange->id_i;
id_len = exchange->initiator ? exchange->id_r_len : exchange->id_i_len;
memset(name, 0, sizeof name);
if (!id || id_len == 0) {
log_print("dns_get_key: ID is missing");
return 0;
}
/* Exchanges (and SAs) don't carry the ID in ISAKMP form */
id -= ISAKMP_GEN_SZ;
id_len += ISAKMP_GEN_SZ - ISAKMP_ID_DATA_OFF;
switch (GET_ISAKMP_ID_TYPE(id)) {
case IPSEC_ID_IPV4_ADDR:
/* We want to lookup a KEY RR in the reverse zone. */
if (id_len < sizeof ip4)
return 0;
memcpy(&ip4, id + ISAKMP_ID_DATA_OFF, sizeof ip4);
snprintf(name, sizeof name, "%d.%d.%d.%d.in-addr.arpa.", ip4
>> 24, (ip4 >> 16) & 0xFF, (ip4 >> 8) & 0xFF, ip4 & 0xFF);
break;
case IPSEC_ID_IPV6_ADDR:
/* XXX Not yet. */
return 0;
break;
case IPSEC_ID_FQDN:
if ((id_len + 1) >= sizeof name)
return 0;
/* ID is not NULL-terminated. Add trailing dot and terminate. */
memcpy(name, id + ISAKMP_ID_DATA_OFF, id_len);
*(name + id_len) = '.';
*(name + id_len + 1) = '\0';
break;
case IPSEC_ID_USER_FQDN:
/*
* Some special handling here. We want to convert the ID
* 'user@host.domain' string into 'user._ipsec.host.domain.'.
*/
if ((id_len + sizeof(DNS_UFQDN_SEPARATOR)) >= sizeof name)
return 0;
/* Look for the '@' separator. */
for (umark = id + ISAKMP_ID_DATA_OFF; (umark - id) < id_len;
umark++)
if (*umark == '@')
break;
if (*umark != '@') {
LOG_DBG((LOG_MISC, 50, "dns_get_key: bad UFQDN ID"));
return 0;
}
*umark++ = '\0';
/* id is now terminated. 'umark', however, is not. */
snprintf(name, sizeof name, "%s%s", id + ISAKMP_ID_DATA_OFF,
DNS_UFQDN_SEPARATOR);
memcpy(name + strlen(name), umark, id_len - strlen(id) - 1);
*(name + id_len + sizeof(DNS_UFQDN_SEPARATOR) - 2) = '.';
*(name + id_len + sizeof(DNS_UFQDN_SEPARATOR) - 1) = '\0';
break;
default:
return 0;
}
LOG_DBG((LOG_MISC, 50, "dns_get_key: trying KEY RR for %s", name));
ret = getrrsetbyname(name, C_IN, T_KEY, 0, &rr);
if (ret) {
LOG_DBG((LOG_MISC, 30, "dns_get_key: no DNS responses "
"(error %d)", ret));
return 0;
}
LOG_DBG((LOG_MISC, 80,
"dns_get_key: rrset class %d type %d ttl %d nrdatas %d nrsigs %d",
rr->rri_rdclass, rr->rri_rdtype, rr->rri_ttl, rr->rri_nrdatas,
rr->rri_nsigs));
/* We don't accept unvalidated data. */
if (!(rr->rri_flags & RRSET_VALIDATED)) {
LOG_DBG((LOG_MISC, 10, "dns_get_key: got unvalidated response"));
freerrset(rr);
return 0;
}
/* Sanity. */
if (rr->rri_nrdatas == 0 || rr->rri_rdtype != T_KEY) {
LOG_DBG((LOG_MISC, 30, "dns_get_key: no KEY RRs received"));
freerrset(rr);
return 0;
}
memset(&key_rr, 0, sizeof key_rr);
/*
* Find a key with the wanted algorithm, if any.
* XXX If there are several keys present, we currently only find the
* first.
*/
for (i = 0; i < rr->rri_nrdatas && key_rr.datalen == 0; i++) {
key_rr.flags = ntohs((u_int16_t) * rr->rri_rdatas[i].rdi_data);
key_rr.protocol = *(rr->rri_rdatas[i].rdi_data + 2);
key_rr.algorithm = *(rr->rri_rdatas[i].rdi_data + 3);
if (key_rr.protocol != DNS_KEYPROTO_IPSEC) {
LOG_DBG((LOG_MISC, 50, "dns_get_key: ignored "
"non-IPsec key"));
continue;
}
if (key_rr.algorithm != algorithm) {
LOG_DBG((LOG_MISC, 50, "dns_get_key: ignored "
"key with other alg"));
continue;
}
key_rr.datalen = rr->rri_rdatas[i].rdi_length - 4;
if (key_rr.datalen <= 0) {
LOG_DBG((LOG_MISC, 50, "dns_get_key: ignored bad key"));
key_rr.datalen = 0;
continue;
}
/* This key seems to fit our requirements... */
key_rr.data = (char *)malloc(key_rr.datalen);
if (!key_rr.data) {
log_error("dns_get_key: malloc (%d) failed",
key_rr.datalen);
freerrset(rr);
return 0;
}
memcpy(key_rr.data, rr->rri_rdatas[i].rdi_data + 4,
key_rr.datalen);
*keylen = key_rr.datalen;
}
freerrset(rr);
if (key_rr.datalen)
return key_rr.data;
return 0;
}
int
dns_RSA_dns_to_x509(u_int8_t *key, int keylen, RSA **rsa_key)
{
RSA *rsa;
int key_offset;
u_int8_t e_len;
if (!key || keylen <= 0) {
log_print("dns_RSA_dns_to_x509: invalid public key");
return -1;
}
rsa = RSA_new();
if (rsa == NULL) {
log_error("dns_RSA_dns_to_x509: failed to allocate new RSA struct");
return -1;
}
e_len = *key;
key_offset = 1;
if (e_len == 0) {
if (keylen < 3) {
log_print("dns_RSA_dns_to_x509: invalid public key");
RSA_free(rsa);
return -1;
}
e_len = *(key + key_offset++) << 8;
e_len += *(key + key_offset++);
}
if (e_len > (keylen - key_offset)) {
log_print("dns_RSA_dns_to_x509: invalid public key");
RSA_free(rsa);
return -1;
}
rsa->e = BN_bin2bn(key + key_offset, e_len, NULL);
key_offset += e_len;
/* XXX if (keylen <= key_offset) -> "invalid public key" ? */
rsa->n = BN_bin2bn(key + key_offset, keylen - key_offset, NULL);
*rsa_key = rsa;
LOG_DBG((LOG_MISC, 30, "dns_RSA_dns_to_x509: got %d bits RSA key",
BN_num_bits(rsa->n)));
return 0;
}
#if notyet
int
dns_RSA_x509_to_dns(RSA *rsa_key, u_int8_t *key, int *keylen)
{
return 0;
}
#endif
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