/* $OpenBSD: kexc25519c.c,v 1.7 2015/01/26 06:10:03 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, void *ctxt); 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, void *ctxt) { struct ssh *ssh = ctxt; 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, 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; }