174 lines
5.4 KiB
C
174 lines
5.4 KiB
C
/* $OpenBSD: kexecdhs.c,v 1.2 2010/09/22 05:01:29 djm Exp $ */
|
|
/*
|
|
* Copyright (c) 2001 Markus Friedl. All rights reserved.
|
|
* Copyright (c) 2010 Damien Miller. 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"
|
|
|
|
#include <sys/types.h>
|
|
#include <string.h>
|
|
#include <signal.h>
|
|
|
|
#include "xmalloc.h"
|
|
#include "buffer.h"
|
|
#include "key.h"
|
|
#include "cipher.h"
|
|
#include "kex.h"
|
|
#include "log.h"
|
|
#include "packet.h"
|
|
#include "dh.h"
|
|
#include "ssh2.h"
|
|
#ifdef GSSAPI
|
|
#include "ssh-gss.h"
|
|
#endif
|
|
#include "monitor_wrap.h"
|
|
|
|
#ifdef OPENSSL_HAS_ECC
|
|
|
|
#include <openssl/ecdh.h>
|
|
|
|
void
|
|
kexecdh_server(Kex *kex)
|
|
{
|
|
EC_POINT *client_public;
|
|
EC_KEY *server_key;
|
|
const EC_GROUP *group;
|
|
BIGNUM *shared_secret;
|
|
Key *server_host_private, *server_host_public;
|
|
u_char *server_host_key_blob = NULL, *signature = NULL;
|
|
u_char *kbuf, *hash;
|
|
u_int klen, slen, sbloblen, hashlen;
|
|
int curve_nid;
|
|
|
|
if ((curve_nid = kex_ecdh_name_to_nid(kex->name)) == -1)
|
|
fatal("%s: unsupported ECDH curve \"%s\"", __func__, kex->name);
|
|
if ((server_key = EC_KEY_new_by_curve_name(curve_nid)) == NULL)
|
|
fatal("%s: EC_KEY_new_by_curve_name failed", __func__);
|
|
if (EC_KEY_generate_key(server_key) != 1)
|
|
fatal("%s: EC_KEY_generate_key failed", __func__);
|
|
group = EC_KEY_get0_group(server_key);
|
|
|
|
#ifdef DEBUG_KEXECDH
|
|
fputs("server private key:\n", stderr);
|
|
key_dump_ec_key(server_key);
|
|
#endif
|
|
|
|
if (kex->load_host_public_key == NULL ||
|
|
kex->load_host_private_key == NULL)
|
|
fatal("Cannot load hostkey");
|
|
server_host_public = kex->load_host_public_key(kex->hostkey_type);
|
|
if (server_host_public == NULL)
|
|
fatal("Unsupported hostkey type %d", kex->hostkey_type);
|
|
server_host_private = kex->load_host_private_key(kex->hostkey_type);
|
|
if (server_host_private == NULL)
|
|
fatal("Missing private key for hostkey type %d",
|
|
kex->hostkey_type);
|
|
|
|
debug("expecting SSH2_MSG_KEX_ECDH_INIT");
|
|
packet_read_expect(SSH2_MSG_KEX_ECDH_INIT);
|
|
if ((client_public = EC_POINT_new(group)) == NULL)
|
|
fatal("%s: EC_POINT_new failed", __func__);
|
|
packet_get_ecpoint(group, client_public);
|
|
packet_check_eom();
|
|
|
|
if (key_ec_validate_public(group, client_public) != 0)
|
|
fatal("%s: invalid client public key", __func__);
|
|
|
|
#ifdef DEBUG_KEXECDH
|
|
fputs("client public key:\n", stderr);
|
|
key_dump_ec_point(group, client_public);
|
|
#endif
|
|
|
|
/* Calculate shared_secret */
|
|
klen = (EC_GROUP_get_degree(group) + 7) / 8;
|
|
kbuf = xmalloc(klen);
|
|
if (ECDH_compute_key(kbuf, klen, client_public,
|
|
server_key, NULL) != (int)klen)
|
|
fatal("%s: ECDH_compute_key failed", __func__);
|
|
|
|
#ifdef DEBUG_KEXDH
|
|
dump_digest("shared secret", kbuf, klen);
|
|
#endif
|
|
if ((shared_secret = BN_new()) == NULL)
|
|
fatal("%s: BN_new failed", __func__);
|
|
if (BN_bin2bn(kbuf, klen, shared_secret) == NULL)
|
|
fatal("%s: BN_bin2bn failed", __func__);
|
|
memset(kbuf, 0, klen);
|
|
xfree(kbuf);
|
|
|
|
/* calc H */
|
|
key_to_blob(server_host_public, &server_host_key_blob, &sbloblen);
|
|
kex_ecdh_hash(
|
|
kex->evp_md,
|
|
group,
|
|
kex->client_version_string,
|
|
kex->server_version_string,
|
|
buffer_ptr(&kex->peer), buffer_len(&kex->peer),
|
|
buffer_ptr(&kex->my), buffer_len(&kex->my),
|
|
server_host_key_blob, sbloblen,
|
|
client_public,
|
|
EC_KEY_get0_public_key(server_key),
|
|
shared_secret,
|
|
&hash, &hashlen
|
|
);
|
|
EC_POINT_clear_free(client_public);
|
|
|
|
/* save session id := H */
|
|
if (kex->session_id == NULL) {
|
|
kex->session_id_len = hashlen;
|
|
kex->session_id = xmalloc(kex->session_id_len);
|
|
memcpy(kex->session_id, hash, kex->session_id_len);
|
|
}
|
|
|
|
/* sign H */
|
|
if (PRIVSEP(key_sign(server_host_private, &signature, &slen,
|
|
hash, hashlen)) < 0)
|
|
fatal("kexdh_server: key_sign failed");
|
|
|
|
/* destroy_sensitive_data(); */
|
|
|
|
/* send server hostkey, ECDH pubkey 'Q_S' and signed H */
|
|
packet_start(SSH2_MSG_KEX_ECDH_REPLY);
|
|
packet_put_string(server_host_key_blob, sbloblen);
|
|
packet_put_ecpoint(group, EC_KEY_get0_public_key(server_key));
|
|
packet_put_string(signature, slen);
|
|
packet_send();
|
|
|
|
xfree(signature);
|
|
xfree(server_host_key_blob);
|
|
/* have keys, free server key */
|
|
EC_KEY_free(server_key);
|
|
|
|
kex_derive_keys(kex, hash, hashlen, shared_secret);
|
|
BN_clear_free(shared_secret);
|
|
kex_finish(kex);
|
|
}
|
|
#else /* OPENSSL_HAS_ECC */
|
|
void
|
|
kexecdh_server(Kex *kex)
|
|
{
|
|
fatal("ECC support is not enabled");
|
|
}
|
|
#endif /* OPENSSL_HAS_ECC */
|