Annotation of src/usr.bin/ssh/kexc25519s.c, Revision 1.13
1.13 ! djm 1: /* $OpenBSD: kexc25519s.c,v 1.12 2018/12/27 03:25:25 djm Exp $ */
1.1 markus 2: /*
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 <sys/types.h>
1.9 dtucker 28: #include <stdio.h>
1.1 markus 29: #include <string.h>
30: #include <signal.h>
31:
1.6 markus 32: #include "sshkey.h"
1.1 markus 33: #include "cipher.h"
1.6 markus 34: #include "digest.h"
1.1 markus 35: #include "kex.h"
36: #include "log.h"
37: #include "packet.h"
38: #include "ssh2.h"
1.6 markus 39: #include "sshbuf.h"
40: #include "ssherr.h"
1.1 markus 41:
1.11 djm 42: static int input_kex_c25519_init(int, u_int32_t, struct ssh *);
1.6 markus 43:
44: int
45: kexc25519_server(struct ssh *ssh)
46: {
47: debug("expecting SSH2_MSG_KEX_ECDH_INIT");
48: ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_INIT, &input_kex_c25519_init);
49: return 0;
50: }
51:
52: static int
1.11 djm 53: input_kex_c25519_init(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 54: {
1.6 markus 55: struct kex *kex = ssh->kex;
56: struct sshkey *server_host_private, *server_host_public;
57: struct sshbuf *shared_secret = NULL;
1.1 markus 58: u_char *server_host_key_blob = NULL, *signature = NULL;
59: u_char server_key[CURVE25519_SIZE];
60: u_char *client_pubkey = NULL;
61: u_char server_pubkey[CURVE25519_SIZE];
1.6 markus 62: u_char hash[SSH_DIGEST_MAX_LENGTH];
63: size_t slen, pklen, sbloblen, hashlen;
64: int r;
1.1 markus 65:
66: /* generate private key */
67: kexc25519_keygen(server_key, server_pubkey);
68: #ifdef DEBUG_KEXECDH
69: dump_digest("server private key:", server_key, sizeof(server_key));
70: #endif
71: if (kex->load_host_public_key == NULL ||
1.6 markus 72: kex->load_host_private_key == NULL) {
73: r = SSH_ERR_INVALID_ARGUMENT;
74: goto out;
75: }
1.8 djm 76: server_host_public = kex->load_host_public_key(kex->hostkey_type,
77: kex->hostkey_nid, ssh);
78: server_host_private = kex->load_host_private_key(kex->hostkey_type,
79: kex->hostkey_nid, ssh);
1.7 djm 80: if (server_host_public == NULL) {
1.6 markus 81: r = SSH_ERR_NO_HOSTKEY_LOADED;
82: goto out;
83: }
1.1 markus 84:
1.6 markus 85: if ((r = sshpkt_get_string(ssh, &client_pubkey, &pklen)) != 0 ||
86: (r = sshpkt_get_end(ssh)) != 0)
87: goto out;
88: if (pklen != CURVE25519_SIZE) {
89: r = SSH_ERR_SIGNATURE_INVALID;
90: goto out;
91: }
1.1 markus 92: #ifdef DEBUG_KEXECDH
93: dump_digest("client public key:", client_pubkey, CURVE25519_SIZE);
94: #endif
95:
1.6 markus 96: if ((shared_secret = sshbuf_new()) == NULL) {
97: r = SSH_ERR_ALLOC_FAIL;
98: goto out;
99: }
100: if ((r = kexc25519_shared_key(server_key, client_pubkey,
101: shared_secret)) < 0)
102: goto out;
1.1 markus 103:
104: /* calc H */
1.6 markus 105: if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob,
106: &sbloblen)) != 0)
107: goto out;
108: hashlen = sizeof(hash);
109: if ((r = kex_c25519_hash(
1.3 djm 110: kex->hash_alg,
1.12 djm 111: kex->client_version,
112: kex->server_version,
1.6 markus 113: sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
114: sshbuf_ptr(kex->my), sshbuf_len(kex->my),
1.1 markus 115: server_host_key_blob, sbloblen,
116: client_pubkey,
117: server_pubkey,
1.6 markus 118: sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
119: hash, &hashlen)) < 0)
120: goto out;
1.1 markus 121:
122: /* save session id := H */
123: if (kex->session_id == NULL) {
124: kex->session_id_len = hashlen;
1.6 markus 125: kex->session_id = malloc(kex->session_id_len);
126: if (kex->session_id == NULL) {
127: r = SSH_ERR_ALLOC_FAIL;
128: goto out;
129: }
1.1 markus 130: memcpy(kex->session_id, hash, kex->session_id_len);
131: }
132:
133: /* sign H */
1.13 ! djm 134: if ((r = kex->sign(ssh, server_host_private, server_host_public,
! 135: &signature, &slen, hash, hashlen, kex->hostkey_alg)) < 0)
1.6 markus 136: goto out;
1.1 markus 137:
138: /* send server hostkey, ECDH pubkey 'Q_S' and signed H */
1.6 markus 139: if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_REPLY)) != 0 ||
140: (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 ||
141: (r = sshpkt_put_string(ssh, server_pubkey, sizeof(server_pubkey))) != 0 ||
142: (r = sshpkt_put_string(ssh, signature, slen)) != 0 ||
143: (r = sshpkt_send(ssh)) != 0)
144: goto out;
145:
146: if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
147: r = kex_send_newkeys(ssh);
148: out:
149: explicit_bzero(hash, sizeof(hash));
150: explicit_bzero(server_key, sizeof(server_key));
151: free(server_host_key_blob);
1.1 markus 152: free(signature);
153: free(client_pubkey);
1.6 markus 154: sshbuf_free(shared_secret);
155: return r;
1.1 markus 156: }
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