kexecdhc.c - security/openssh-library - Rivoreo Source Code Repositories

 /* $OpenBSD: kexecdhc.c,v 1.9 2015/01/19 20:16:15 markus 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"

 #if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC)

 #include <sys/types.h>

 #include <stdio.h>
 #include <string.h>
 #include <signal.h>

 #include <openssl/ecdh.h>

 #include "sshkey.h"
 #include "cipher.h"
 #include "digest.h"
 #include "kex.h"
 #include "log.h"
 #include "packet.h"
 #include "dh.h"
 #include "ssh2.h"
 #include "dispatch.h"
 #include "compat.h"
 #include "ssherr.h"
 #include "sshbuf.h"

 static int input_kex_ecdh_reply(int, u_int32_t, void *);

 int
 kexecdh_client(struct ssh *ssh)
 {
 	struct kex *kex = ssh->kex;
 	EC_KEY *client_key = NULL;
 	const EC_GROUP *group;
 	const EC_POINT *public_key;
 	int r;

 	if ((client_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL) {
 		r = SSH_ERR_ALLOC_FAIL;
 		goto out;
 	}
 	if (EC_KEY_generate_key(client_key) != 1) {
 		r = SSH_ERR_LIBCRYPTO_ERROR;
 		goto out;
 	}
 	group = EC_KEY_get0_group(client_key);
 	public_key = EC_KEY_get0_public_key(client_key);

 	if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_INIT)) != 0 ||
 	    (r = sshpkt_put_ec(ssh, public_key, group)) != 0 ||
 	    (r = sshpkt_send(ssh)) != 0)
 		goto out;
 	debug("sending SSH2_MSG_KEX_ECDH_INIT");

 #ifdef DEBUG_KEXECDH
 	fputs("client private key:\n", stderr);
 	sshkey_dump_ec_key(client_key);
 #endif
 	kex->ec_client_key = client_key;
 	kex->ec_group = group;
 	client_key = NULL;	/* owned by the kex */

 	debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
 	ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_REPLY, &input_kex_ecdh_reply);
 	r = 0;
  out:
 	if (client_key)
 		EC_KEY_free(client_key);
 	return r;
 }

 static int
 input_kex_ecdh_reply(int type, u_int32_t seq, void *ctxt)
 {
 	struct ssh *ssh = ctxt;
 	struct kex *kex = ssh->kex;
 	const EC_GROUP *group;
 	EC_POINT *server_public = NULL;
 	EC_KEY *client_key;
 	BIGNUM *shared_secret = NULL;
 	struct sshkey *server_host_key = NULL;
 	u_char *server_host_key_blob = NULL, *signature = NULL;
 	u_char *kbuf = NULL;
 	u_char hash[SSH_DIGEST_MAX_LENGTH];
 	size_t slen, sbloblen;
 	size_t klen = 0, hashlen;
 	int r;

 	if (kex->verify_host_key == NULL) {
 		r = SSH_ERR_INVALID_ARGUMENT;
 		goto out;
 	}
 	group = kex->ec_group;
 	client_key = kex->ec_client_key;

 	/* hostkey */
 	if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
 	    &sbloblen)) != 0 ||
 	    (r = sshkey_from_blob(server_host_key_blob, sbloblen,
 	    &server_host_key)) != 0)
 		goto out;
 	if (server_host_key->type != kex->hostkey_type) {
 		r = SSH_ERR_KEY_TYPE_MISMATCH;
 		goto out;
 	}
 	if (kex->verify_host_key(server_host_key, ssh) == -1) {
 		r = SSH_ERR_SIGNATURE_INVALID;
 		goto out;
 	}

 	/* Q_S, server public key */
 	/* signed H */
 	if ((server_public = EC_POINT_new(group)) == NULL) {
 		r = SSH_ERR_ALLOC_FAIL;
 		goto out;
 	}
 	if ((r = sshpkt_get_ec(ssh, server_public, group)) != 0 ||
 	    (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
 	    (r = sshpkt_get_end(ssh)) != 0)
 		goto out;

 #ifdef DEBUG_KEXECDH
 	fputs("server public key:\n", stderr);
 	sshkey_dump_ec_point(group, server_public);
 #endif
 	if (sshkey_ec_validate_public(group, server_public) != 0) {
 		sshpkt_disconnect(ssh, "invalid server public key");
 		r = SSH_ERR_MESSAGE_INCOMPLETE;
 		goto out;
 	}

 	klen = (EC_GROUP_get_degree(group) + 7) / 8;
 	if ((kbuf = malloc(klen)) == NULL ||
 	    (shared_secret = BN_new()) == NULL) {
 		r = SSH_ERR_ALLOC_FAIL;
 		goto out;
 	}
 	if (ECDH_compute_key(kbuf, klen, server_public,
 	    client_key, NULL) != (int)klen ||
 	    BN_bin2bn(kbuf, klen, shared_secret) == NULL) {
 		r = SSH_ERR_LIBCRYPTO_ERROR;
 		goto out;
 	}

 #ifdef DEBUG_KEXECDH
 	dump_digest("shared secret", kbuf, klen);
 #endif
 	/* calc and verify H */
 	hashlen = sizeof(hash);
 	if ((r = kex_ecdh_hash(
 	    kex->hash_alg,
 	    group,
 	    kex->client_version_string,
 	    kex->server_version_string,
 	    sshbuf_ptr(kex->my), sshbuf_len(kex->my),
 	    sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
 	    server_host_key_blob, sbloblen,
 	    EC_KEY_get0_public_key(client_key),
 	    server_public,
 	    shared_secret,
 	    hash, &hashlen)) != 0)
 		goto out;

 	if ((r = sshkey_verify(server_host_key, signature, slen, hash,
 	    hashlen, ssh->compat)) != 0)
 		goto out;

 	/* save session id */
 	if (kex->session_id == NULL) {
 		kex->session_id_len = hashlen;
 		kex->session_id = malloc(kex->session_id_len);
 		if (kex->session_id == NULL) {
 			r = SSH_ERR_ALLOC_FAIL;
 			goto out;
 		}
 		memcpy(kex->session_id, hash, kex->session_id_len);
 	}

 	if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
 		r = kex_send_newkeys(ssh);
  out:
 	explicit_bzero(hash, sizeof(hash));
 	if (kex->ec_client_key) {
 		EC_KEY_free(kex->ec_client_key);
 		kex->ec_client_key = NULL;
 	}
 	if (server_public)
 		EC_POINT_clear_free(server_public);
 	if (kbuf) {
 		explicit_bzero(kbuf, klen);
 		free(kbuf);
 	}
 	if (shared_secret)
 		BN_clear_free(shared_secret);
 	sshkey_free(server_host_key);
 	free(server_host_key_blob);
 	free(signature);
 	return r;
 }
 #endif /* defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC) */
	/* $OpenBSD: kexecdhc.c,v 1.9 2015/01/19 20:16:15 markus 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"

	#if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC)

	#include <sys/types.h>

	#include <stdio.h>
	#include <string.h>
	#include <signal.h>

	#include <openssl/ecdh.h>

	#include "sshkey.h"
	#include "cipher.h"
	#include "digest.h"
	#include "kex.h"
	#include "log.h"
	#include "packet.h"
	#include "dh.h"
	#include "ssh2.h"
	#include "dispatch.h"
	#include "compat.h"
	#include "ssherr.h"
	#include "sshbuf.h"

	static int input_kex_ecdh_reply(int, u_int32_t, void *);

	int
	kexecdh_client(struct ssh *ssh)
	{
	struct kex *kex = ssh->kex;
	EC_KEY *client_key = NULL;
	const EC_GROUP *group;
	const EC_POINT *public_key;
	int r;

	if ((client_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL) {
	r = SSH_ERR_ALLOC_FAIL;
	goto out;
	}
	if (EC_KEY_generate_key(client_key) != 1) {
	r = SSH_ERR_LIBCRYPTO_ERROR;
	goto out;
	}
	group = EC_KEY_get0_group(client_key);
	public_key = EC_KEY_get0_public_key(client_key);

	if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_INIT)) != 0 \|\|
	(r = sshpkt_put_ec(ssh, public_key, group)) != 0 \|\|
	(r = sshpkt_send(ssh)) != 0)
	goto out;
	debug("sending SSH2_MSG_KEX_ECDH_INIT");

	#ifdef DEBUG_KEXECDH
	fputs("client private key:\n", stderr);
	sshkey_dump_ec_key(client_key);
	#endif
	kex->ec_client_key = client_key;
	kex->ec_group = group;
	client_key = NULL; /* owned by the kex */

	debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
	ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_REPLY, &input_kex_ecdh_reply);
	r = 0;
	out:
	if (client_key)
	EC_KEY_free(client_key);
	return r;
	}

	static int
	input_kex_ecdh_reply(int type, u_int32_t seq, void *ctxt)
	{
	struct ssh *ssh = ctxt;
	struct kex *kex = ssh->kex;
	const EC_GROUP *group;
	EC_POINT *server_public = NULL;
	EC_KEY *client_key;
	BIGNUM *shared_secret = NULL;
	struct sshkey *server_host_key = NULL;
	u_char server_host_key_blob = NULL, signature = NULL;
	u_char *kbuf = NULL;
	u_char hash[SSH_DIGEST_MAX_LENGTH];
	size_t slen, sbloblen;
	size_t klen = 0, hashlen;
	int r;

	if (kex->verify_host_key == NULL) {
	r = SSH_ERR_INVALID_ARGUMENT;
	goto out;
	}
	group = kex->ec_group;
	client_key = kex->ec_client_key;

	/* hostkey */
	if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
	&sbloblen)) != 0 \|\|
	(r = sshkey_from_blob(server_host_key_blob, sbloblen,
	&server_host_key)) != 0)
	goto out;
	if (server_host_key->type != kex->hostkey_type) {
	r = SSH_ERR_KEY_TYPE_MISMATCH;
	goto out;
	}
	if (kex->verify_host_key(server_host_key, ssh) == -1) {
	r = SSH_ERR_SIGNATURE_INVALID;
	goto out;
	}

	/* Q_S, server public key */
	/* signed H */
	if ((server_public = EC_POINT_new(group)) == NULL) {
	r = SSH_ERR_ALLOC_FAIL;
	goto out;
	}
	if ((r = sshpkt_get_ec(ssh, server_public, group)) != 0 \|\|
	(r = sshpkt_get_string(ssh, &signature, &slen)) != 0 \|\|
	(r = sshpkt_get_end(ssh)) != 0)
	goto out;

	#ifdef DEBUG_KEXECDH
	fputs("server public key:\n", stderr);
	sshkey_dump_ec_point(group, server_public);
	#endif
	if (sshkey_ec_validate_public(group, server_public) != 0) {
	sshpkt_disconnect(ssh, "invalid server public key");
	r = SSH_ERR_MESSAGE_INCOMPLETE;
	goto out;
	}

	klen = (EC_GROUP_get_degree(group) + 7) / 8;
	if ((kbuf = malloc(klen)) == NULL \|\|
	(shared_secret = BN_new()) == NULL) {
	r = SSH_ERR_ALLOC_FAIL;
	goto out;
	}
	if (ECDH_compute_key(kbuf, klen, server_public,
	client_key, NULL) != (int)klen \|\|
	BN_bin2bn(kbuf, klen, shared_secret) == NULL) {
	r = SSH_ERR_LIBCRYPTO_ERROR;
	goto out;
	}

	#ifdef DEBUG_KEXECDH
	dump_digest("shared secret", kbuf, klen);
	#endif
	/* calc and verify H */
	hashlen = sizeof(hash);
	if ((r = kex_ecdh_hash(
	kex->hash_alg,
	group,
	kex->client_version_string,
	kex->server_version_string,
	sshbuf_ptr(kex->my), sshbuf_len(kex->my),
	sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
	server_host_key_blob, sbloblen,
	EC_KEY_get0_public_key(client_key),
	server_public,
	shared_secret,
	hash, &hashlen)) != 0)
	goto out;

	if ((r = sshkey_verify(server_host_key, signature, slen, hash,
	hashlen, ssh->compat)) != 0)
	goto out;

	/* save session id */
	if (kex->session_id == NULL) {
	kex->session_id_len = hashlen;
	kex->session_id = malloc(kex->session_id_len);
	if (kex->session_id == NULL) {
	r = SSH_ERR_ALLOC_FAIL;
	goto out;
	}
	memcpy(kex->session_id, hash, kex->session_id_len);
	}

	if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
	r = kex_send_newkeys(ssh);
	out:
	explicit_bzero(hash, sizeof(hash));
	if (kex->ec_client_key) {
	EC_KEY_free(kex->ec_client_key);
	kex->ec_client_key = NULL;
	}
	if (server_public)
	EC_POINT_clear_free(server_public);
	if (kbuf) {
	explicit_bzero(kbuf, klen);
	free(kbuf);
	}
	if (shared_secret)
	BN_clear_free(shared_secret);
	sshkey_free(server_host_key);
	free(server_host_key_blob);
	free(signature);
	return r;
	}
	#endif /* defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC) */