Annotation of src/usr.bin/ssh/kexc25519c.c, Revision 1.11
1.11 ! djm 1: /* $OpenBSD: kexc25519c.c,v 1.10 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: * Redistribution and use in source and binary forms, with or without
8: * modification, are permitted provided that the following conditions
9: * are met:
10: * 1. Redistributions of source code must retain the above copyright
11: * notice, this list of conditions and the following disclaimer.
12: * 2. Redistributions in binary form must reproduce the above copyright
13: * notice, this list of conditions and the following disclaimer in the
14: * documentation and/or other materials provided with the distribution.
15: *
16: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26: */
27:
28: #include <sys/types.h>
29:
30: #include <stdio.h>
31: #include <string.h>
32: #include <signal.h>
33:
1.6 markus 34: #include "sshkey.h"
1.1 markus 35: #include "cipher.h"
36: #include "kex.h"
37: #include "log.h"
38: #include "packet.h"
39: #include "ssh2.h"
1.6 markus 40: #include "sshbuf.h"
41: #include "digest.h"
42: #include "ssherr.h"
1.1 markus 43:
1.6 markus 44: static int
1.8 djm 45: input_kex_c25519_reply(int type, u_int32_t seq, struct ssh *ssh);
1.6 markus 46:
47: int
48: kexc25519_client(struct ssh *ssh)
1.1 markus 49: {
1.6 markus 50: struct kex *kex = ssh->kex;
51: int r;
1.1 markus 52:
1.6 markus 53: kexc25519_keygen(kex->c25519_client_key, kex->c25519_client_pubkey);
1.1 markus 54: #ifdef DEBUG_KEXECDH
1.6 markus 55: dump_digest("client private key:", kex->c25519_client_key,
56: sizeof(kex->c25519_client_key));
1.1 markus 57: #endif
1.6 markus 58: if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_INIT)) != 0 ||
59: (r = sshpkt_put_string(ssh, kex->c25519_client_pubkey,
60: sizeof(kex->c25519_client_pubkey))) != 0 ||
61: (r = sshpkt_send(ssh)) != 0)
62: return r;
1.1 markus 63:
64: debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
1.6 markus 65: ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_REPLY, &input_kex_c25519_reply);
66: return 0;
67: }
68:
69: static int
1.8 djm 70: input_kex_c25519_reply(int type, u_int32_t seq, struct ssh *ssh)
1.6 markus 71: {
72: struct kex *kex = ssh->kex;
73: struct sshkey *server_host_key = NULL;
74: struct sshbuf *shared_secret = NULL;
75: u_char *server_pubkey = NULL;
76: u_char *server_host_key_blob = NULL, *signature = NULL;
77: u_char hash[SSH_DIGEST_MAX_LENGTH];
78: size_t slen, pklen, sbloblen, hashlen;
79: int r;
80:
81: if (kex->verify_host_key == NULL) {
82: r = SSH_ERR_INVALID_ARGUMENT;
83: goto out;
84: }
1.1 markus 85:
86: /* hostkey */
1.6 markus 87: if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
88: &sbloblen)) != 0 ||
89: (r = sshkey_from_blob(server_host_key_blob, sbloblen,
90: &server_host_key)) != 0)
91: goto out;
1.7 djm 92: if (server_host_key->type != kex->hostkey_type ||
93: (kex->hostkey_type == KEY_ECDSA &&
94: server_host_key->ecdsa_nid != kex->hostkey_nid)) {
1.6 markus 95: r = SSH_ERR_KEY_TYPE_MISMATCH;
96: goto out;
97: }
98: if (kex->verify_host_key(server_host_key, ssh) == -1) {
99: r = SSH_ERR_SIGNATURE_INVALID;
100: goto out;
101: }
1.1 markus 102:
103: /* Q_S, server public key */
1.6 markus 104: /* signed H */
105: if ((r = sshpkt_get_string(ssh, &server_pubkey, &pklen)) != 0 ||
106: (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
107: (r = sshpkt_get_end(ssh)) != 0)
108: goto out;
109: if (pklen != CURVE25519_SIZE) {
110: r = SSH_ERR_SIGNATURE_INVALID;
111: goto out;
112: }
1.1 markus 113:
114: #ifdef DEBUG_KEXECDH
115: dump_digest("server public key:", server_pubkey, CURVE25519_SIZE);
116: #endif
117:
1.6 markus 118: if ((shared_secret = sshbuf_new()) == NULL) {
119: r = SSH_ERR_ALLOC_FAIL;
120: goto out;
121: }
122: if ((r = kexc25519_shared_key(kex->c25519_client_key, server_pubkey,
123: shared_secret)) < 0)
124: goto out;
1.1 markus 125:
126: /* calc and verify H */
1.6 markus 127: hashlen = sizeof(hash);
128: if ((r = kex_c25519_hash(
1.3 djm 129: kex->hash_alg,
1.10 djm 130: kex->client_version,
131: kex->server_version,
1.6 markus 132: sshbuf_ptr(kex->my), sshbuf_len(kex->my),
133: sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
1.1 markus 134: server_host_key_blob, sbloblen,
1.6 markus 135: kex->c25519_client_pubkey,
1.1 markus 136: server_pubkey,
1.6 markus 137: sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
138: hash, &hashlen)) < 0)
139: goto out;
140:
141: if ((r = sshkey_verify(server_host_key, signature, slen, hash, hashlen,
1.9 djm 142: kex->hostkey_alg, ssh->compat)) != 0)
1.6 markus 143: goto out;
144:
145: if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
146: r = kex_send_newkeys(ssh);
147: out:
148: explicit_bzero(hash, sizeof(hash));
149: explicit_bzero(kex->c25519_client_key, sizeof(kex->c25519_client_key));
150: free(server_host_key_blob);
151: free(server_pubkey);
152: free(signature);
153: sshkey_free(server_host_key);
154: sshbuf_free(shared_secret);
155: return r;
1.1 markus 156: }
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