blob: 24027253363ee8e72f44164cd46666caac855fee [file] [log] [blame]
dtucker@openbsd.orga4b9d2c2015-04-27 00:37:53 +00001/* $OpenBSD: kexc25519s.c,v 1.9 2015/04/27 00:37:53 dtucker Exp $ */
Damien Miller094003f2013-11-04 22:59:27 +11002/*
3 * Copyright (c) 2001 Markus Friedl. All rights reserved.
4 * Copyright (c) 2010 Damien Miller. All rights reserved.
5 * Copyright (c) 2013 Aris Adamantiadis. All rights reserved.
6 *
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include "includes.h"
28
29#include <sys/types.h>
dtucker@openbsd.orga4b9d2c2015-04-27 00:37:53 +000030#include <stdio.h>
Damien Miller094003f2013-11-04 22:59:27 +110031#include <string.h>
32#include <signal.h>
33
markus@openbsd.org57d10cb2015-01-19 20:16:15 +000034#include "sshkey.h"
Damien Miller094003f2013-11-04 22:59:27 +110035#include "cipher.h"
markus@openbsd.org57d10cb2015-01-19 20:16:15 +000036#include "digest.h"
Damien Miller094003f2013-11-04 22:59:27 +110037#include "kex.h"
38#include "log.h"
39#include "packet.h"
40#include "ssh2.h"
markus@openbsd.org57d10cb2015-01-19 20:16:15 +000041#include "sshbuf.h"
42#include "ssherr.h"
Damien Miller094003f2013-11-04 22:59:27 +110043
markus@openbsd.org57d10cb2015-01-19 20:16:15 +000044static int input_kex_c25519_init(int, u_int32_t, void *);
45
46int
47kexc25519_server(struct ssh *ssh)
Damien Miller094003f2013-11-04 22:59:27 +110048{
markus@openbsd.org57d10cb2015-01-19 20:16:15 +000049 debug("expecting SSH2_MSG_KEX_ECDH_INIT");
50 ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_INIT, &input_kex_c25519_init);
51 return 0;
52}
53
54static int
55input_kex_c25519_init(int type, u_int32_t seq, void *ctxt)
56{
57 struct ssh *ssh = ctxt;
58 struct kex *kex = ssh->kex;
59 struct sshkey *server_host_private, *server_host_public;
60 struct sshbuf *shared_secret = NULL;
Damien Miller094003f2013-11-04 22:59:27 +110061 u_char *server_host_key_blob = NULL, *signature = NULL;
62 u_char server_key[CURVE25519_SIZE];
63 u_char *client_pubkey = NULL;
64 u_char server_pubkey[CURVE25519_SIZE];
markus@openbsd.org57d10cb2015-01-19 20:16:15 +000065 u_char hash[SSH_DIGEST_MAX_LENGTH];
66 size_t slen, pklen, sbloblen, hashlen;
67 int r;
Damien Miller094003f2013-11-04 22:59:27 +110068
69 /* generate private key */
70 kexc25519_keygen(server_key, server_pubkey);
71#ifdef DEBUG_KEXECDH
72 dump_digest("server private key:", server_key, sizeof(server_key));
73#endif
Damien Miller094003f2013-11-04 22:59:27 +110074 if (kex->load_host_public_key == NULL ||
markus@openbsd.org57d10cb2015-01-19 20:16:15 +000075 kex->load_host_private_key == NULL) {
76 r = SSH_ERR_INVALID_ARGUMENT;
77 goto out;
78 }
djm@openbsd.org5104db72015-01-26 06:10:03 +000079 server_host_public = kex->load_host_public_key(kex->hostkey_type,
80 kex->hostkey_nid, ssh);
81 server_host_private = kex->load_host_private_key(kex->hostkey_type,
82 kex->hostkey_nid, ssh);
djm@openbsd.orge2cc6be2015-01-20 07:55:33 +000083 if (server_host_public == NULL) {
markus@openbsd.org57d10cb2015-01-19 20:16:15 +000084 r = SSH_ERR_NO_HOSTKEY_LOADED;
85 goto out;
86 }
Damien Miller094003f2013-11-04 22:59:27 +110087
markus@openbsd.org57d10cb2015-01-19 20:16:15 +000088 if ((r = sshpkt_get_string(ssh, &client_pubkey, &pklen)) != 0 ||
89 (r = sshpkt_get_end(ssh)) != 0)
90 goto out;
91 if (pklen != CURVE25519_SIZE) {
92 r = SSH_ERR_SIGNATURE_INVALID;
93 goto out;
94 }
Damien Miller094003f2013-11-04 22:59:27 +110095#ifdef DEBUG_KEXECDH
96 dump_digest("client public key:", client_pubkey, CURVE25519_SIZE);
97#endif
98
markus@openbsd.org57d10cb2015-01-19 20:16:15 +000099 if ((shared_secret = sshbuf_new()) == NULL) {
100 r = SSH_ERR_ALLOC_FAIL;
101 goto out;
102 }
103 if ((r = kexc25519_shared_key(server_key, client_pubkey,
104 shared_secret)) < 0)
105 goto out;
Damien Miller094003f2013-11-04 22:59:27 +1100106
107 /* calc H */
markus@openbsd.org57d10cb2015-01-19 20:16:15 +0000108 if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob,
109 &sbloblen)) != 0)
110 goto out;
111 hashlen = sizeof(hash);
112 if ((r = kex_c25519_hash(
Damien Millerb3051d02014-01-10 10:58:53 +1100113 kex->hash_alg,
Damien Miller094003f2013-11-04 22:59:27 +1100114 kex->client_version_string,
115 kex->server_version_string,
markus@openbsd.org57d10cb2015-01-19 20:16:15 +0000116 sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
117 sshbuf_ptr(kex->my), sshbuf_len(kex->my),
Damien Miller094003f2013-11-04 22:59:27 +1100118 server_host_key_blob, sbloblen,
119 client_pubkey,
120 server_pubkey,
markus@openbsd.org57d10cb2015-01-19 20:16:15 +0000121 sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
122 hash, &hashlen)) < 0)
123 goto out;
Damien Miller094003f2013-11-04 22:59:27 +1100124
125 /* save session id := H */
126 if (kex->session_id == NULL) {
127 kex->session_id_len = hashlen;
markus@openbsd.org57d10cb2015-01-19 20:16:15 +0000128 kex->session_id = malloc(kex->session_id_len);
129 if (kex->session_id == NULL) {
130 r = SSH_ERR_ALLOC_FAIL;
131 goto out;
132 }
Damien Miller094003f2013-11-04 22:59:27 +1100133 memcpy(kex->session_id, hash, kex->session_id_len);
134 }
135
136 /* sign H */
markus@openbsd.org57d10cb2015-01-19 20:16:15 +0000137 if ((r = kex->sign(server_host_private, server_host_public,
138 &signature, &slen, hash, hashlen, ssh->compat)) < 0)
139 goto out;
Damien Miller094003f2013-11-04 22:59:27 +1100140
141 /* send server hostkey, ECDH pubkey 'Q_S' and signed H */
markus@openbsd.org57d10cb2015-01-19 20:16:15 +0000142 if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_REPLY)) != 0 ||
143 (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 ||
144 (r = sshpkt_put_string(ssh, server_pubkey, sizeof(server_pubkey))) != 0 ||
145 (r = sshpkt_put_string(ssh, signature, slen)) != 0 ||
146 (r = sshpkt_send(ssh)) != 0)
147 goto out;
Damien Miller094003f2013-11-04 22:59:27 +1100148
markus@openbsd.org57d10cb2015-01-19 20:16:15 +0000149 if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
150 r = kex_send_newkeys(ssh);
151out:
152 explicit_bzero(hash, sizeof(hash));
153 explicit_bzero(server_key, sizeof(server_key));
Damien Miller094003f2013-11-04 22:59:27 +1100154 free(server_host_key_blob);
markus@openbsd.org57d10cb2015-01-19 20:16:15 +0000155 free(signature);
Damien Miller094003f2013-11-04 22:59:27 +1100156 free(client_pubkey);
markus@openbsd.org57d10cb2015-01-19 20:16:15 +0000157 sshbuf_free(shared_secret);
158 return r;
Damien Miller094003f2013-11-04 22:59:27 +1100159}