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Diffstat (limited to 'kexecdhs.c')
| -rw-r--r-- | kexecdhs.c | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/kexecdhs.c b/kexecdhs.c new file mode 100644 index 0000000..af4f303 --- /dev/null +++ b/kexecdhs.c @@ -0,0 +1,203 @@ +/* $OpenBSD: kexecdhs.c,v 1.17 2018/02/07 02:06:51 jsing 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 <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 "ssh2.h" + +#include "dispatch.h" +#include "compat.h" +#include "ssherr.h" +#include "sshbuf.h" + +static int input_kex_ecdh_init(int, u_int32_t, struct ssh *); + +int +kexecdh_server(struct ssh *ssh) +{ + debug("expecting SSH2_MSG_KEX_ECDH_INIT"); + ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_INIT, &input_kex_ecdh_init); + return 0; +} + +static int +input_kex_ecdh_init(int type, u_int32_t seq, struct ssh *ssh) +{ + struct kex *kex = ssh->kex; + EC_POINT *client_public; + EC_KEY *server_key = NULL; + const EC_GROUP *group; + const EC_POINT *public_key; + BIGNUM *shared_secret = NULL; + struct sshkey *server_host_private, *server_host_public; + 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 ((server_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + if (EC_KEY_generate_key(server_key) != 1) { + r = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + group = EC_KEY_get0_group(server_key); + +#ifdef DEBUG_KEXECDH + fputs("server private key:\n", stderr); + sshkey_dump_ec_key(server_key); +#endif + + if (kex->load_host_public_key == NULL || + kex->load_host_private_key == NULL) { + r = SSH_ERR_INVALID_ARGUMENT; + goto out; + } + server_host_public = kex->load_host_public_key(kex->hostkey_type, + kex->hostkey_nid, ssh); + server_host_private = kex->load_host_private_key(kex->hostkey_type, + kex->hostkey_nid, ssh); + if (server_host_public == NULL) { + r = SSH_ERR_NO_HOSTKEY_LOADED; + goto out; + } + if ((client_public = EC_POINT_new(group)) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + if ((r = sshpkt_get_ec(ssh, client_public, group)) != 0 || + (r = sshpkt_get_end(ssh)) != 0) + goto out; + +#ifdef DEBUG_KEXECDH + fputs("client public key:\n", stderr); + sshkey_dump_ec_point(group, client_public); +#endif + if (sshkey_ec_validate_public(group, client_public) != 0) { + sshpkt_disconnect(ssh, "invalid client public key"); + r = SSH_ERR_MESSAGE_INCOMPLETE; + goto out; + } + + /* Calculate shared_secret */ + 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, client_public, + server_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 H */ + if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob, + &sbloblen)) != 0) + goto out; + hashlen = sizeof(hash); + if ((r = kex_ecdh_hash( + kex->hash_alg, + group, + kex->client_version_string, + kex->server_version_string, + sshbuf_ptr(kex->peer), sshbuf_len(kex->peer), + sshbuf_ptr(kex->my), sshbuf_len(kex->my), + server_host_key_blob, sbloblen, + client_public, + EC_KEY_get0_public_key(server_key), + shared_secret, + hash, &hashlen)) != 0) + goto out; + + /* save session id := H */ + 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); + } + + /* sign H */ + if ((r = kex->sign(server_host_private, server_host_public, &signature, + &slen, hash, hashlen, kex->hostkey_alg, ssh->compat)) < 0) + goto out; + + /* destroy_sensitive_data(); */ + + public_key = EC_KEY_get0_public_key(server_key); + /* send server hostkey, ECDH pubkey 'Q_S' and signed H */ + if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_REPLY)) != 0 || + (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 || + (r = sshpkt_put_ec(ssh, public_key, group)) != 0 || + (r = sshpkt_put_string(ssh, signature, slen)) != 0 || + (r = sshpkt_send(ssh)) != 0) + goto out; + + if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0) + r = kex_send_newkeys(ssh); + out: + explicit_bzero(hash, sizeof(hash)); + EC_KEY_free(kex->ec_client_key); + kex->ec_client_key = NULL; + EC_KEY_free(server_key); + if (kbuf) { + explicit_bzero(kbuf, klen); + free(kbuf); + } + BN_clear_free(shared_secret); + free(server_host_key_blob); + free(signature); + return r; +} +#endif /* defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC) */ + |