/* $OpenBSD: kex.c,v 1.136 2018/02/07 02:06:50 jsing Exp $ */
/*
* Copyright (c) 2000, 2001 Markus Friedl. 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 <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef WITH_OPENSSL
#include <openssl/crypto.h>
#include <openssl/dh.h>
#endif
#include "ssh2.h"
#include "packet.h"
#include "compat.h"
#include "cipher.h"
#include "sshkey.h"
#include "kex.h"
#include "log.h"
#include "mac.h"
#include "match.h"
#include "misc.h"
#include "dispatch.h"
#include "monitor.h"
#include "ssherr.h"
#include "sshbuf.h"
#include "digest.h"
/* prototype */
static int kex_choose_conf(struct ssh *);
static int kex_input_newkeys(int, u_int32_t, struct ssh *);
static const char *proposal_names[PROPOSAL_MAX] = {
"KEX algorithms",
"host key algorithms",
"ciphers ctos",
"ciphers stoc",
"MACs ctos",
"MACs stoc",
"compression ctos",
"compression stoc",
"languages ctos",
"languages stoc",
};
struct kexalg {
char *name;
u_int type;
int ec_nid;
int hash_alg;
};
static const struct kexalg kexalgs[] = {
#ifdef WITH_OPENSSL
{ KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
{ KEX_DH14_SHA1, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
{ KEX_DH14_SHA256, KEX_DH_GRP14_SHA256, 0, SSH_DIGEST_SHA256 },
{ KEX_DH16_SHA512, KEX_DH_GRP16_SHA512, 0, SSH_DIGEST_SHA512 },
{ KEX_DH18_SHA512, KEX_DH_GRP18_SHA512, 0, SSH_DIGEST_SHA512 },
{ KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
#ifdef HAVE_EVP_SHA256
{ KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 },
#endif /* HAVE_EVP_SHA256 */
#ifdef OPENSSL_HAS_ECC
{ KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2,
NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
{ KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1,
SSH_DIGEST_SHA384 },
# ifdef OPENSSL_HAS_NISTP521
{ KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1,
SSH_DIGEST_SHA512 },
# endif /* OPENSSL_HAS_NISTP521 */
#endif /* OPENSSL_HAS_ECC */
#endif /* WITH_OPENSSL */
#if defined(HAVE_EVP_SHA256) || !defined(WITH_OPENSSL)
{ KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
{ KEX_CURVE25519_SHA256_OLD, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
#endif /* HAVE_EVP_SHA256 || !WITH_OPENSSL */
{ NULL, -1, -1, -1},
};
char *
kex_alg_list(char sep)
{
char *ret = NULL, *tmp;
size_t nlen, rlen = 0;
const struct kexalg *k;
for (k = kexalgs; k->name != NULL; k++) {
if (ret != NULL)
ret[rlen++] = sep;
nlen = strlen(k->name);
if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
free(ret);
return NULL;
}
ret = tmp;
memcpy(ret + rlen, k->name, nlen + 1);
rlen += nlen;
}
return ret;
}
static const struct kexalg *
kex_alg_by_name(const char *name)
{
const struct kexalg *k;
for (k = kexalgs; k->name != NULL; k++) {
if (strcmp(k->name, name) == 0)
return k;
}
return NULL;
}
/* Validate KEX method name list */
int
kex_names_valid(const char *names)
{
char *s,<