4f52dfbb8d
This completely removes client-side support for the SSH 1 protocol, which was already disabled in 12 but is still enabled in 11. For that reason, we will not be able to merge 7.6p1 or newer back to 11.
228 lines
6.3 KiB
C
228 lines
6.3 KiB
C
/* $OpenBSD: kexecdhc.c,v 1.11 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 "includes.h"
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#if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC)
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#include <sys/types.h>
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#include <stdio.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 "dh.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_reply(int, u_int32_t, struct ssh *);
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int
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kexecdh_client(struct ssh *ssh)
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{
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struct kex *kex = ssh->kex;
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EC_KEY *client_key = NULL;
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const EC_GROUP *group;
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const EC_POINT *public_key;
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int r;
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if ((client_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(client_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(client_key);
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public_key = EC_KEY_get0_public_key(client_key);
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if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_INIT)) != 0 ||
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(r = sshpkt_put_ec(ssh, public_key, group)) != 0 ||
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(r = sshpkt_send(ssh)) != 0)
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goto out;
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debug("sending SSH2_MSG_KEX_ECDH_INIT");
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#ifdef DEBUG_KEXECDH
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fputs("client private key:\n", stderr);
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sshkey_dump_ec_key(client_key);
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#endif
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kex->ec_client_key = client_key;
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kex->ec_group = group;
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client_key = NULL; /* owned by the kex */
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debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
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ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_REPLY, &input_kex_ecdh_reply);
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r = 0;
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out:
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if (client_key)
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EC_KEY_free(client_key);
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return r;
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}
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static int
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input_kex_ecdh_reply(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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const EC_GROUP *group;
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EC_POINT *server_public = NULL;
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EC_KEY *client_key;
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BIGNUM *shared_secret = NULL;
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struct sshkey *server_host_key = NULL;
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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 (kex->verify_host_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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group = kex->ec_group;
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client_key = kex->ec_client_key;
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/* hostkey */
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if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
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&sbloblen)) != 0 ||
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(r = sshkey_from_blob(server_host_key_blob, sbloblen,
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&server_host_key)) != 0)
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goto out;
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if (server_host_key->type != kex->hostkey_type ||
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(kex->hostkey_type == KEY_ECDSA &&
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server_host_key->ecdsa_nid != kex->hostkey_nid)) {
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r = SSH_ERR_KEY_TYPE_MISMATCH;
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goto out;
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}
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if (kex->verify_host_key(server_host_key, ssh) == -1) {
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r = SSH_ERR_SIGNATURE_INVALID;
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goto out;
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}
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/* Q_S, server public key */
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/* signed H */
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if ((server_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, server_public, group)) != 0 ||
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(r = sshpkt_get_string(ssh, &signature, &slen)) != 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("server public key:\n", stderr);
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sshkey_dump_ec_point(group, server_public);
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#endif
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if (sshkey_ec_validate_public(group, server_public) != 0) {
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sshpkt_disconnect(ssh, "invalid server 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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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, server_public,
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client_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 and verify H */
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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->my), sshbuf_len(kex->my),
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sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
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server_host_key_blob, sbloblen,
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EC_KEY_get0_public_key(client_key),
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server_public,
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shared_secret,
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hash, &hashlen)) != 0)
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goto out;
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if ((r = sshkey_verify(server_host_key, signature, slen, hash,
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hashlen, ssh->compat)) != 0)
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goto out;
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/* save session id */
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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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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_public)
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EC_POINT_clear_free(server_public);
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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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sshkey_free(server_host_key);
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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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}
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#endif /* defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC) */
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