2006-07-24 04:13:33 +00:00
|
|
|
/* $OpenBSD: dns.c,v 1.21 2006/07/22 20:48:23 stevesk Exp $ */
|
2003-05-15 00:19:46 +00:00
|
|
|
|
|
|
|
/*
|
|
|
|
* Copyright (c) 2003 Wesley Griffin. All rights reserved.
|
|
|
|
* Copyright (c) 2003 Jakob Schlyter. 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 "includes.h"
|
|
|
|
|
2006-07-10 11:08:03 +00:00
|
|
|
#include <sys/types.h>
|
|
|
|
#include <sys/socket.h>
|
|
|
|
|
2006-07-24 04:51:00 +00:00
|
|
|
#include <netdb.h>
|
2006-07-24 04:13:33 +00:00
|
|
|
#include <string.h>
|
2003-05-15 00:19:46 +00:00
|
|
|
|
|
|
|
#include "xmalloc.h"
|
|
|
|
#include "key.h"
|
|
|
|
#include "dns.h"
|
|
|
|
#include "log.h"
|
|
|
|
|
|
|
|
static const char *errset_text[] = {
|
|
|
|
"success", /* 0 ERRSET_SUCCESS */
|
|
|
|
"out of memory", /* 1 ERRSET_NOMEMORY */
|
|
|
|
"general failure", /* 2 ERRSET_FAIL */
|
|
|
|
"invalid parameter", /* 3 ERRSET_INVAL */
|
|
|
|
"name does not exist", /* 4 ERRSET_NONAME */
|
|
|
|
"data does not exist", /* 5 ERRSET_NODATA */
|
|
|
|
};
|
|
|
|
|
|
|
|
static const char *
|
2004-06-22 02:56:01 +00:00
|
|
|
dns_result_totext(unsigned int res)
|
2003-05-15 00:19:46 +00:00
|
|
|
{
|
2004-06-22 02:56:01 +00:00
|
|
|
switch (res) {
|
2003-05-15 00:19:46 +00:00
|
|
|
case ERRSET_SUCCESS:
|
|
|
|
return errset_text[ERRSET_SUCCESS];
|
|
|
|
case ERRSET_NOMEMORY:
|
|
|
|
return errset_text[ERRSET_NOMEMORY];
|
|
|
|
case ERRSET_FAIL:
|
|
|
|
return errset_text[ERRSET_FAIL];
|
|
|
|
case ERRSET_INVAL:
|
|
|
|
return errset_text[ERRSET_INVAL];
|
|
|
|
case ERRSET_NONAME:
|
|
|
|
return errset_text[ERRSET_NONAME];
|
|
|
|
case ERRSET_NODATA:
|
|
|
|
return errset_text[ERRSET_NODATA];
|
|
|
|
default:
|
|
|
|
return "unknown error";
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Read SSHFP parameters from key buffer.
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
dns_read_key(u_int8_t *algorithm, u_int8_t *digest_type,
|
2003-11-17 10:19:29 +00:00
|
|
|
u_char **digest, u_int *digest_len, const Key *key)
|
2003-05-15 00:19:46 +00:00
|
|
|
{
|
|
|
|
int success = 0;
|
|
|
|
|
|
|
|
switch (key->type) {
|
|
|
|
case KEY_RSA:
|
|
|
|
*algorithm = SSHFP_KEY_RSA;
|
|
|
|
break;
|
|
|
|
case KEY_DSA:
|
|
|
|
*algorithm = SSHFP_KEY_DSA;
|
|
|
|
break;
|
|
|
|
default:
|
2005-11-05 04:09:27 +00:00
|
|
|
*algorithm = SSHFP_KEY_RESERVED; /* 0 */
|
2003-05-15 00:19:46 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
if (*algorithm) {
|
|
|
|
*digest_type = SSHFP_HASH_SHA1;
|
|
|
|
*digest = key_fingerprint_raw(key, SSH_FP_SHA1, digest_len);
|
2005-11-05 04:09:27 +00:00
|
|
|
if (*digest == NULL)
|
|
|
|
fatal("dns_read_key: null from key_fingerprint_raw()");
|
2003-05-15 00:19:46 +00:00
|
|
|
success = 1;
|
|
|
|
} else {
|
|
|
|
*digest_type = SSHFP_HASH_RESERVED;
|
|
|
|
*digest = NULL;
|
|
|
|
*digest_len = 0;
|
|
|
|
success = 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
return success;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Read SSHFP parameters from rdata buffer.
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
dns_read_rdata(u_int8_t *algorithm, u_int8_t *digest_type,
|
|
|
|
u_char **digest, u_int *digest_len, u_char *rdata, int rdata_len)
|
|
|
|
{
|
|
|
|
int success = 0;
|
|
|
|
|
|
|
|
*algorithm = SSHFP_KEY_RESERVED;
|
|
|
|
*digest_type = SSHFP_HASH_RESERVED;
|
|
|
|
|
|
|
|
if (rdata_len >= 2) {
|
|
|
|
*algorithm = rdata[0];
|
|
|
|
*digest_type = rdata[1];
|
|
|
|
*digest_len = rdata_len - 2;
|
|
|
|
|
|
|
|
if (*digest_len > 0) {
|
|
|
|
*digest = (u_char *) xmalloc(*digest_len);
|
|
|
|
memcpy(*digest, rdata + 2, *digest_len);
|
|
|
|
} else {
|
2006-03-25 13:06:48 +00:00
|
|
|
*digest = (u_char *)xstrdup("");
|
2003-05-15 00:19:46 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
success = 1;
|
|
|
|
}
|
|
|
|
|
|
|
|
return success;
|
|
|
|
}
|
|
|
|
|
2005-05-26 02:03:31 +00:00
|
|
|
/*
|
|
|
|
* Check if hostname is numerical.
|
|
|
|
* Returns -1 if hostname is numeric, 0 otherwise
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
is_numeric_hostname(const char *hostname)
|
|
|
|
{
|
|
|
|
struct addrinfo hints, *ai;
|
|
|
|
|
|
|
|
memset(&hints, 0, sizeof(hints));
|
|
|
|
hints.ai_socktype = SOCK_DGRAM;
|
|
|
|
hints.ai_flags = AI_NUMERICHOST;
|
|
|
|
|
|
|
|
if (getaddrinfo(hostname, "0", &hints, &ai) == 0) {
|
|
|
|
freeaddrinfo(ai);
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
2003-05-15 00:19:46 +00:00
|
|
|
|
|
|
|
/*
|
|
|
|
* Verify the given hostname, address and host key using DNS.
|
2003-11-21 12:48:55 +00:00
|
|
|
* Returns 0 if lookup succeeds, -1 otherwise
|
2003-05-15 00:19:46 +00:00
|
|
|
*/
|
|
|
|
int
|
|
|
|
verify_host_key_dns(const char *hostname, struct sockaddr *address,
|
2003-11-17 10:19:29 +00:00
|
|
|
const Key *hostkey, int *flags)
|
2003-05-15 00:19:46 +00:00
|
|
|
{
|
2005-06-17 02:59:34 +00:00
|
|
|
u_int counter;
|
2003-05-15 00:19:46 +00:00
|
|
|
int result;
|
|
|
|
struct rrsetinfo *fingerprints = NULL;
|
|
|
|
|
|
|
|
u_int8_t hostkey_algorithm;
|
|
|
|
u_int8_t hostkey_digest_type;
|
|
|
|
u_char *hostkey_digest;
|
|
|
|
u_int hostkey_digest_len;
|
|
|
|
|
|
|
|
u_int8_t dnskey_algorithm;
|
|
|
|
u_int8_t dnskey_digest_type;
|
|
|
|
u_char *dnskey_digest;
|
|
|
|
u_int dnskey_digest_len;
|
|
|
|
|
2003-11-17 10:19:29 +00:00
|
|
|
*flags = 0;
|
2003-05-15 00:19:46 +00:00
|
|
|
|
2005-11-05 04:11:15 +00:00
|
|
|
debug3("verify_host_key_dns");
|
2003-05-15 00:19:46 +00:00
|
|
|
if (hostkey == NULL)
|
|
|
|
fatal("No key to look up!");
|
|
|
|
|
2005-05-26 02:03:31 +00:00
|
|
|
if (is_numeric_hostname(hostname)) {
|
|
|
|
debug("skipped DNS lookup for numerical hostname");
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
2003-05-15 00:19:46 +00:00
|
|
|
result = getrrsetbyname(hostname, DNS_RDATACLASS_IN,
|
|
|
|
DNS_RDATATYPE_SSHFP, 0, &fingerprints);
|
|
|
|
if (result) {
|
|
|
|
verbose("DNS lookup error: %s", dns_result_totext(result));
|
2003-11-17 10:19:29 +00:00
|
|
|
return -1;
|
2003-05-15 00:19:46 +00:00
|
|
|
}
|
|
|
|
|
2003-11-17 10:19:29 +00:00
|
|
|
if (fingerprints->rri_flags & RRSET_VALIDATED) {
|
|
|
|
*flags |= DNS_VERIFY_SECURE;
|
|
|
|
debug("found %d secure fingerprints in DNS",
|
|
|
|
fingerprints->rri_nrdatas);
|
|
|
|
} else {
|
|
|
|
debug("found %d insecure fingerprints in DNS",
|
|
|
|
fingerprints->rri_nrdatas);
|
2003-05-15 00:19:46 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
/* Initialize host key parameters */
|
|
|
|
if (!dns_read_key(&hostkey_algorithm, &hostkey_digest_type,
|
|
|
|
&hostkey_digest, &hostkey_digest_len, hostkey)) {
|
|
|
|
error("Error calculating host key fingerprint.");
|
2003-05-15 03:27:28 +00:00
|
|
|
freerrset(fingerprints);
|
2003-11-17 10:19:29 +00:00
|
|
|
return -1;
|
2003-05-15 00:19:46 +00:00
|
|
|
}
|
|
|
|
|
2003-11-17 10:19:29 +00:00
|
|
|
if (fingerprints->rri_nrdatas)
|
|
|
|
*flags |= DNS_VERIFY_FOUND;
|
|
|
|
|
2005-11-05 04:06:38 +00:00
|
|
|
for (counter = 0; counter < fingerprints->rri_nrdatas; counter++) {
|
2003-05-15 00:19:46 +00:00
|
|
|
/*
|
|
|
|
* Extract the key from the answer. Ignore any badly
|
|
|
|
* formatted fingerprints.
|
|
|
|
*/
|
|
|
|
if (!dns_read_rdata(&dnskey_algorithm, &dnskey_digest_type,
|
|
|
|
&dnskey_digest, &dnskey_digest_len,
|
|
|
|
fingerprints->rri_rdatas[counter].rdi_data,
|
|
|
|
fingerprints->rri_rdatas[counter].rdi_length)) {
|
|
|
|
verbose("Error parsing fingerprint from DNS.");
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Check if the current key is the same as the given key */
|
|
|
|
if (hostkey_algorithm == dnskey_algorithm &&
|
|
|
|
hostkey_digest_type == dnskey_digest_type) {
|
|
|
|
|
|
|
|
if (hostkey_digest_len == dnskey_digest_len &&
|
|
|
|
memcmp(hostkey_digest, dnskey_digest,
|
|
|
|
hostkey_digest_len) == 0) {
|
|
|
|
|
2003-11-17 10:19:29 +00:00
|
|
|
*flags |= DNS_VERIFY_MATCH;
|
2003-05-15 00:19:46 +00:00
|
|
|
}
|
|
|
|
}
|
2005-11-05 04:09:27 +00:00
|
|
|
xfree(dnskey_digest);
|
2003-05-15 00:19:46 +00:00
|
|
|
}
|
|
|
|
|
2005-11-05 04:09:27 +00:00
|
|
|
xfree(hostkey_digest); /* from key_fingerprint_raw() */
|
2003-05-15 00:19:46 +00:00
|
|
|
freerrset(fingerprints);
|
|
|
|
|
2003-11-17 10:19:29 +00:00
|
|
|
if (*flags & DNS_VERIFY_FOUND)
|
|
|
|
if (*flags & DNS_VERIFY_MATCH)
|
|
|
|
debug("matching host key fingerprint found in DNS");
|
|
|
|
else
|
|
|
|
debug("mismatching host key fingerprint found in DNS");
|
|
|
|
else
|
|
|
|
debug("no host key fingerprint found in DNS");
|
2003-05-15 00:19:46 +00:00
|
|
|
|
2003-11-17 10:19:29 +00:00
|
|
|
return 0;
|
2003-05-15 00:19:46 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Export the fingerprint of a key as a DNS resource record
|
|
|
|
*/
|
|
|
|
int
|
2003-11-17 10:19:29 +00:00
|
|
|
export_dns_rr(const char *hostname, const Key *key, FILE *f, int generic)
|
2003-05-15 00:19:46 +00:00
|
|
|
{
|
|
|
|
u_int8_t rdata_pubkey_algorithm = 0;
|
|
|
|
u_int8_t rdata_digest_type = SSHFP_HASH_SHA1;
|
|
|
|
u_char *rdata_digest;
|
|
|
|
u_int rdata_digest_len;
|
|
|
|
|
2005-06-17 02:59:34 +00:00
|
|
|
u_int i;
|
2003-05-15 00:19:46 +00:00
|
|
|
int success = 0;
|
|
|
|
|
|
|
|
if (dns_read_key(&rdata_pubkey_algorithm, &rdata_digest_type,
|
2005-11-05 04:11:15 +00:00
|
|
|
&rdata_digest, &rdata_digest_len, key)) {
|
2003-05-15 00:19:46 +00:00
|
|
|
|
|
|
|
if (generic)
|
|
|
|
fprintf(f, "%s IN TYPE%d \\# %d %02x %02x ", hostname,
|
|
|
|
DNS_RDATATYPE_SSHFP, 2 + rdata_digest_len,
|
|
|
|
rdata_pubkey_algorithm, rdata_digest_type);
|
|
|
|
else
|
|
|
|
fprintf(f, "%s IN SSHFP %d %d ", hostname,
|
|
|
|
rdata_pubkey_algorithm, rdata_digest_type);
|
|
|
|
|
|
|
|
for (i = 0; i < rdata_digest_len; i++)
|
|
|
|
fprintf(f, "%02x", rdata_digest[i]);
|
|
|
|
fprintf(f, "\n");
|
2005-11-05 04:09:27 +00:00
|
|
|
xfree(rdata_digest); /* from key_fingerprint_raw() */
|
2003-05-15 00:19:46 +00:00
|
|
|
success = 1;
|
|
|
|
} else {
|
2005-11-05 04:11:15 +00:00
|
|
|
error("export_dns_rr: unsupported algorithm");
|
2003-05-15 00:19:46 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
return success;
|
|
|
|
}
|