GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: usr.bin/ssh/lib/../kexecdhs.c Lines: 0 79 0.0 %
Date: 2017-11-13 Branches: 0 56 0.0 %

Line Branch Exec Source
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/* $OpenBSD: kexecdhs.c,v 1.16 2017/05/30 14:23:52 markus Exp $ */
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/*
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 * Copyright (c) 2001 Markus Friedl.  All rights reserved.
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 * Copyright (c) 2010 Damien Miller.  All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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#include <sys/types.h>
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#include <string.h>
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#include <signal.h>
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#include <openssl/ecdh.h>
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#include "sshkey.h"
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#include "cipher.h"
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#include "digest.h"
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#include "kex.h"
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#include "log.h"
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#include "packet.h"
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#include "ssh2.h"
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#include "dispatch.h"
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#include "compat.h"
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#include "ssherr.h"
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#include "sshbuf.h"
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static int input_kex_ecdh_init(int, u_int32_t, struct ssh *);
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int
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kexecdh_server(struct ssh *ssh)
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{
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	debug("expecting SSH2_MSG_KEX_ECDH_INIT");
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	ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_INIT, &input_kex_ecdh_init);
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	return 0;
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}
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static int
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input_kex_ecdh_init(int type, u_int32_t seq, struct ssh *ssh)
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{
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	struct kex *kex = ssh->kex;
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	EC_POINT *client_public;
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	EC_KEY *server_key = NULL;
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	const EC_GROUP *group;
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	const EC_POINT *public_key;
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	BIGNUM *shared_secret = NULL;
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	struct sshkey *server_host_private, *server_host_public;
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	u_char *server_host_key_blob = NULL, *signature = NULL;
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	u_char *kbuf = NULL;
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	u_char hash[SSH_DIGEST_MAX_LENGTH];
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	size_t slen, sbloblen;
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	size_t klen = 0, hashlen;
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	int r;
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	if ((server_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL) {
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		r = SSH_ERR_ALLOC_FAIL;
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		goto out;
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	}
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	if (EC_KEY_generate_key(server_key) != 1) {
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		r = SSH_ERR_LIBCRYPTO_ERROR;
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		goto out;
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	}
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	group = EC_KEY_get0_group(server_key);
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#ifdef DEBUG_KEXECDH
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	fputs("server private key:\n", stderr);
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	sshkey_dump_ec_key(server_key);
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#endif
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	if (kex->load_host_public_key == NULL ||
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	    kex->load_host_private_key == NULL) {
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		r = SSH_ERR_INVALID_ARGUMENT;
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		goto out;
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	}
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	server_host_public = kex->load_host_public_key(kex->hostkey_type,
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	    kex->hostkey_nid, ssh);
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	server_host_private = kex->load_host_private_key(kex->hostkey_type,
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	    kex->hostkey_nid, ssh);
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	if (server_host_public == NULL) {
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		r = SSH_ERR_NO_HOSTKEY_LOADED;
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		goto out;
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	}
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	if ((client_public = EC_POINT_new(group)) == NULL) {
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		r = SSH_ERR_ALLOC_FAIL;
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		goto out;
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	}
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	if ((r = sshpkt_get_ec(ssh, client_public, group)) != 0 ||
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	    (r = sshpkt_get_end(ssh)) != 0)
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		goto out;
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#ifdef DEBUG_KEXECDH
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	fputs("client public key:\n", stderr);
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	sshkey_dump_ec_point(group, client_public);
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#endif
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	if (sshkey_ec_validate_public(group, client_public) != 0) {
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		sshpkt_disconnect(ssh, "invalid client public key");
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		r = SSH_ERR_MESSAGE_INCOMPLETE;
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		goto out;
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	}
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	/* Calculate shared_secret */
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	klen = (EC_GROUP_get_degree(group) + 7) / 8;
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	if ((kbuf = malloc(klen)) == NULL ||
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	    (shared_secret = BN_new()) == NULL) {
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		r = SSH_ERR_ALLOC_FAIL;
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		goto out;
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	}
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	if (ECDH_compute_key(kbuf, klen, client_public,
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	    server_key, NULL) != (int)klen ||
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	    BN_bin2bn(kbuf, klen, shared_secret) == NULL) {
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		r = SSH_ERR_LIBCRYPTO_ERROR;
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		goto out;
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	}
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#ifdef DEBUG_KEXECDH
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	dump_digest("shared secret", kbuf, klen);
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#endif
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	/* calc H */
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	if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob,
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	    &sbloblen)) != 0)
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		goto out;
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	hashlen = sizeof(hash);
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	if ((r = kex_ecdh_hash(
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	    kex->hash_alg,
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	    group,
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	    kex->client_version_string,
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	    kex->server_version_string,
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	    sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
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	    sshbuf_ptr(kex->my), sshbuf_len(kex->my),
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	    server_host_key_blob, sbloblen,
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	    client_public,
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	    EC_KEY_get0_public_key(server_key),
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	    shared_secret,
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	    hash, &hashlen)) != 0)
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		goto out;
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	/* save session id := H */
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	if (kex->session_id == NULL) {
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		kex->session_id_len = hashlen;
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		kex->session_id = malloc(kex->session_id_len);
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		if (kex->session_id == NULL) {
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			r = SSH_ERR_ALLOC_FAIL;
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			goto out;
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		}
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		memcpy(kex->session_id, hash, kex->session_id_len);
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	}
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	/* sign H */
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	if ((r = kex->sign(server_host_private, server_host_public, &signature,
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	     &slen, hash, hashlen, kex->hostkey_alg, ssh->compat)) < 0)
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		goto out;
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	/* destroy_sensitive_data(); */
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	public_key = EC_KEY_get0_public_key(server_key);
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	/* send server hostkey, ECDH pubkey 'Q_S' and signed H */
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	if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_REPLY)) != 0 ||
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	    (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 ||
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	    (r = sshpkt_put_ec(ssh, public_key, group)) != 0 ||
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	    (r = sshpkt_put_string(ssh, signature, slen)) != 0 ||
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	    (r = sshpkt_send(ssh)) != 0)
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		goto out;
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	if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
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		r = kex_send_newkeys(ssh);
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 out:
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	explicit_bzero(hash, sizeof(hash));
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	if (kex->ec_client_key) {
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		EC_KEY_free(kex->ec_client_key);
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		kex->ec_client_key = NULL;
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	}
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	if (server_key)
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		EC_KEY_free(server_key);
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	if (kbuf) {
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		explicit_bzero(kbuf, klen);
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		free(kbuf);
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	}
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	if (shared_secret)
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		BN_clear_free(shared_secret);
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	free(server_host_key_blob);
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	free(signature);
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	return r;
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}