diff options
Diffstat (limited to 'kexc25519c.c')
| -rw-r--r-- | kexc25519c.c | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/kexc25519c.c b/kexc25519c.c new file mode 100644 index 0000000..a8d9214 --- /dev/null +++ b/kexc25519c.c @@ -0,0 +1,169 @@ +/* $OpenBSD: kexc25519c.c,v 1.9 2017/12/18 02:25:15 djm Exp $ */ +/* + * Copyright (c) 2001 Markus Friedl. All rights reserved. + * Copyright (c) 2010 Damien Miller. All rights reserved. + * Copyright (c) 2013 Aris Adamantiadis. 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 <sys/types.h> + +#include <stdio.h> +#include <string.h> +#include <signal.h> + +#include "sshkey.h" +#include "cipher.h" +#include "kex.h" +#include "log.h" +#include "packet.h" +#include "ssh2.h" +#include "sshbuf.h" +#include "digest.h" +#include "ssherr.h" + +static int +input_kex_c25519_reply(int type, u_int32_t seq, struct ssh *ssh); + +int +kexc25519_client(struct ssh *ssh) +{ + struct kex *kex = ssh->kex; + int r; + + kexc25519_keygen(kex->c25519_client_key, kex->c25519_client_pubkey); +#ifdef DEBUG_KEXECDH + dump_digest("client private key:", kex->c25519_client_key, + sizeof(kex->c25519_client_key)); +#endif + if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_INIT)) != 0 || + (r = sshpkt_put_string(ssh, kex->c25519_client_pubkey, + sizeof(kex->c25519_client_pubkey))) != 0 || + (r = sshpkt_send(ssh)) != 0) + return r; + + debug("expecting SSH2_MSG_KEX_ECDH_REPLY"); + ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_REPLY, &input_kex_c25519_reply); + return 0; +} + +static int +input_kex_c25519_reply(int type, u_int32_t seq, struct ssh *ssh) +{ + struct kex *kex = ssh->kex; + struct sshkey *server_host_key = NULL; + struct sshbuf *shared_secret = NULL; + u_char *server_pubkey = NULL; + u_char *server_host_key_blob = NULL, *signature = NULL; + u_char hash[SSH_DIGEST_MAX_LENGTH]; + size_t slen, pklen, sbloblen, hashlen; + int r; + + if (kex->verify_host_key == NULL) { + r = SSH_ERR_INVALID_ARGUMENT; + goto out; + } + + /* 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 || + (kex->hostkey_type == KEY_ECDSA && + server_host_key->ecdsa_nid != kex->hostkey_nid)) { + 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 ((r = sshpkt_get_string(ssh, &server_pubkey, &pklen)) != 0 || + (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 || + (r = sshpkt_get_end(ssh)) != 0) + goto out; + if (pklen != CURVE25519_SIZE) { + r = SSH_ERR_SIGNATURE_INVALID; + goto out; + } + +#ifdef DEBUG_KEXECDH + dump_digest("server public key:", server_pubkey, CURVE25519_SIZE); +#endif + + if ((shared_secret = sshbuf_new()) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + if ((r = kexc25519_shared_key(kex->c25519_client_key, server_pubkey, + shared_secret)) < 0) + goto out; + + /* calc and verify H */ + hashlen = sizeof(hash); + if ((r = kex_c25519_hash( + kex->hash_alg, + 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, + kex->c25519_client_pubkey, + server_pubkey, + sshbuf_ptr(shared_secret), sshbuf_len(shared_secret), + hash, &hashlen)) < 0) + goto out; + + if ((r = sshkey_verify(server_host_key, signature, slen, hash, hashlen, + kex->hostkey_alg, 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(ssh, hash, hashlen, shared_secret)) == 0) + r = kex_send_newkeys(ssh); +out: + explicit_bzero(hash, sizeof(hash)); + explicit_bzero(kex->c25519_client_key, sizeof(kex->c25519_client_key)); + free(server_host_key_blob); + free(server_pubkey); + free(signature); + sshkey_free(server_host_key); + sshbuf_free(shared_secret); + return r; +} |