Annotation of src/usr.bin/ssh/kexc25519s.c, Revision 1.10
1.10 ! markus 1: /* $OpenBSD: kexc25519s.c,v 1.9 2015/04/27 00:37:53 dtucker 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:
1.6 markus 42: static int input_kex_c25519_init(int, u_int32_t, void *);
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
53: input_kex_c25519_init(int type, u_int32_t seq, void *ctxt)
1.1 markus 54: {
1.6 markus 55: struct ssh *ssh = ctxt;
56: struct kex *kex = ssh->kex;
57: struct sshkey *server_host_private, *server_host_public;
58: struct sshbuf *shared_secret = NULL;
1.1 markus 59: u_char *server_host_key_blob = NULL, *signature = NULL;
60: u_char server_key[CURVE25519_SIZE];
61: u_char *client_pubkey = NULL;
62: u_char server_pubkey[CURVE25519_SIZE];
1.6 markus 63: u_char hash[SSH_DIGEST_MAX_LENGTH];
64: size_t slen, pklen, sbloblen, hashlen;
65: int r;
1.1 markus 66:
67: /* generate private key */
68: kexc25519_keygen(server_key, server_pubkey);
69: #ifdef DEBUG_KEXECDH
70: dump_digest("server private key:", server_key, sizeof(server_key));
71: #endif
72: if (kex->load_host_public_key == NULL ||
1.6 markus 73: kex->load_host_private_key == NULL) {
74: r = SSH_ERR_INVALID_ARGUMENT;
75: goto out;
76: }
1.8 djm 77: server_host_public = kex->load_host_public_key(kex->hostkey_type,
78: kex->hostkey_nid, ssh);
79: server_host_private = kex->load_host_private_key(kex->hostkey_type,
80: kex->hostkey_nid, ssh);
1.7 djm 81: if (server_host_public == NULL) {
1.6 markus 82: r = SSH_ERR_NO_HOSTKEY_LOADED;
83: goto out;
84: }
1.1 markus 85:
1.6 markus 86: if ((r = sshpkt_get_string(ssh, &client_pubkey, &pklen)) != 0 ||
87: (r = sshpkt_get_end(ssh)) != 0)
88: goto out;
89: if (pklen != CURVE25519_SIZE) {
90: r = SSH_ERR_SIGNATURE_INVALID;
91: goto out;
92: }
1.1 markus 93: #ifdef DEBUG_KEXECDH
94: dump_digest("client public key:", client_pubkey, CURVE25519_SIZE);
95: #endif
96:
1.6 markus 97: if ((shared_secret = sshbuf_new()) == NULL) {
98: r = SSH_ERR_ALLOC_FAIL;
99: goto out;
100: }
101: if ((r = kexc25519_shared_key(server_key, client_pubkey,
102: shared_secret)) < 0)
103: goto out;
1.1 markus 104:
105: /* calc H */
1.6 markus 106: if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob,
107: &sbloblen)) != 0)
108: goto out;
109: hashlen = sizeof(hash);
110: if ((r = kex_c25519_hash(
1.3 djm 111: kex->hash_alg,
1.1 markus 112: kex->client_version_string,
113: kex->server_version_string,
1.6 markus 114: sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
115: sshbuf_ptr(kex->my), sshbuf_len(kex->my),
1.1 markus 116: server_host_key_blob, sbloblen,
117: client_pubkey,
118: server_pubkey,
1.6 markus 119: sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
120: hash, &hashlen)) < 0)
121: goto out;
1.1 markus 122:
123: /* save session id := H */
124: if (kex->session_id == NULL) {
125: kex->session_id_len = hashlen;
1.6 markus 126: kex->session_id = malloc(kex->session_id_len);
127: if (kex->session_id == NULL) {
128: r = SSH_ERR_ALLOC_FAIL;
129: goto out;
130: }
1.1 markus 131: memcpy(kex->session_id, hash, kex->session_id_len);
132: }
133:
134: /* sign H */
1.10 ! markus 135: if ((r = kex->sign(server_host_private, server_host_public, &signature,
! 136: &slen, hash, hashlen, kex->hostkey_alg, ssh->compat)) < 0)
1.6 markus 137: goto out;
1.1 markus 138:
139: /* send server hostkey, ECDH pubkey 'Q_S' and signed H */
1.6 markus 140: if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_REPLY)) != 0 ||
141: (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 ||
142: (r = sshpkt_put_string(ssh, server_pubkey, sizeof(server_pubkey))) != 0 ||
143: (r = sshpkt_put_string(ssh, signature, slen)) != 0 ||
144: (r = sshpkt_send(ssh)) != 0)
145: goto out;
146:
147: if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
148: r = kex_send_newkeys(ssh);
149: out:
150: explicit_bzero(hash, sizeof(hash));
151: explicit_bzero(server_key, sizeof(server_key));
152: free(server_host_key_blob);
1.1 markus 153: free(signature);
154: free(client_pubkey);
1.6 markus 155: sshbuf_free(shared_secret);
156: return r;
1.1 markus 157: }
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