Annotation of src/usr.bin/ssh/kexdhs.c, Revision 1.23
1.23 ! markus 1: /* $OpenBSD: kexdhs.c,v 1.22 2015/01/26 06:10:03 djm Exp $ */
1.1 markus 2: /*
3: * Copyright (c) 2001 Markus Friedl. All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: *
14: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24: */
25:
1.6 stevesk 26:
1.7 deraadt 27: #include <sys/types.h>
1.6 stevesk 28: #include <string.h>
1.7 deraadt 29: #include <signal.h>
1.12 djm 30:
31: #include <openssl/dh.h>
1.1 markus 32:
1.20 markus 33: #include "sshkey.h"
1.7 deraadt 34: #include "cipher.h"
1.20 markus 35: #include "digest.h"
1.1 markus 36: #include "kex.h"
37: #include "log.h"
38: #include "packet.h"
39: #include "dh.h"
40: #include "ssh2.h"
41:
1.20 markus 42: #include "dispatch.h"
43: #include "compat.h"
44: #include "ssherr.h"
45: #include "sshbuf.h"
46:
47: static int input_kex_dh_init(int, u_int32_t, void *);
48:
49: int
50: kexdh_server(struct ssh *ssh)
1.1 markus 51: {
1.20 markus 52: struct kex *kex = ssh->kex;
53: int r;
1.1 markus 54:
55: /* generate server DH public key */
1.2 djm 56: switch (kex->kex_type) {
57: case KEX_DH_GRP1_SHA1:
1.20 markus 58: kex->dh = dh_new_group1();
1.2 djm 59: break;
60: case KEX_DH_GRP14_SHA1:
1.20 markus 61: kex->dh = dh_new_group14();
1.2 djm 62: break;
63: default:
1.20 markus 64: r = SSH_ERR_INVALID_ARGUMENT;
65: goto out;
1.2 djm 66: }
1.20 markus 67: if (kex->dh == NULL) {
68: r = SSH_ERR_ALLOC_FAIL;
69: goto out;
70: }
71: if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0)
72: goto out;
1.1 markus 73:
74: debug("expecting SSH2_MSG_KEXDH_INIT");
1.20 markus 75: ssh_dispatch_set(ssh, SSH2_MSG_KEXDH_INIT, &input_kex_dh_init);
76: r = 0;
77: out:
78: return r;
79: }
80:
81: int
82: input_kex_dh_init(int type, u_int32_t seq, void *ctxt)
83: {
84: struct ssh *ssh = ctxt;
85: struct kex *kex = ssh->kex;
86: BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
87: struct sshkey *server_host_public, *server_host_private;
88: u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL;
89: u_char hash[SSH_DIGEST_MAX_LENGTH];
90: size_t sbloblen, slen;
91: size_t klen = 0, hashlen;
92: int kout, r;
1.1 markus 93:
1.11 djm 94: if (kex->load_host_public_key == NULL ||
1.20 markus 95: kex->load_host_private_key == NULL) {
96: r = SSH_ERR_INVALID_ARGUMENT;
97: goto out;
98: }
1.22 djm 99: server_host_public = kex->load_host_public_key(kex->hostkey_type,
100: kex->hostkey_nid, ssh);
101: server_host_private = kex->load_host_private_key(kex->hostkey_type,
102: kex->hostkey_nid, ssh);
1.21 djm 103: if (server_host_public == NULL) {
1.20 markus 104: r = SSH_ERR_NO_HOSTKEY_LOADED;
105: goto out;
106: }
1.1 markus 107:
108: /* key, cert */
1.20 markus 109: if ((dh_client_pub = BN_new()) == NULL) {
110: r = SSH_ERR_ALLOC_FAIL;
111: goto out;
112: }
113: if ((r = sshpkt_get_bignum2(ssh, dh_client_pub)) != 0 ||
114: (r = sshpkt_get_end(ssh)) != 0)
115: goto out;
1.1 markus 116:
117: #ifdef DEBUG_KEXDH
118: fprintf(stderr, "dh_client_pub= ");
119: BN_print_fp(stderr, dh_client_pub);
120: fprintf(stderr, "\n");
121: debug("bits %d", BN_num_bits(dh_client_pub));
122: #endif
123:
124: #ifdef DEBUG_KEXDH
1.20 markus 125: DHparams_print_fp(stderr, kex->dh);
1.1 markus 126: fprintf(stderr, "pub= ");
1.20 markus 127: BN_print_fp(stderr, kex->dh->pub_key);
1.1 markus 128: fprintf(stderr, "\n");
129: #endif
1.20 markus 130: if (!dh_pub_is_valid(kex->dh, dh_client_pub)) {
131: sshpkt_disconnect(ssh, "bad client public DH value");
132: r = SSH_ERR_MESSAGE_INCOMPLETE;
133: goto out;
134: }
1.1 markus 135:
1.20 markus 136: klen = DH_size(kex->dh);
137: if ((kbuf = malloc(klen)) == NULL ||
138: (shared_secret = BN_new()) == NULL) {
139: r = SSH_ERR_ALLOC_FAIL;
140: goto out;
141: }
142: if ((kout = DH_compute_key(kbuf, dh_client_pub, kex->dh)) < 0 ||
143: BN_bin2bn(kbuf, kout, shared_secret) == NULL) {
144: r = SSH_ERR_LIBCRYPTO_ERROR;
145: goto out;
146: }
1.1 markus 147: #ifdef DEBUG_KEXDH
148: dump_digest("shared secret", kbuf, kout);
149: #endif
1.20 markus 150: if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob,
151: &sbloblen)) != 0)
152: goto out;
1.1 markus 153: /* calc H */
1.20 markus 154: hashlen = sizeof(hash);
155: if ((r = kex_dh_hash(
1.1 markus 156: kex->client_version_string,
157: kex->server_version_string,
1.20 markus 158: sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
159: sshbuf_ptr(kex->my), sshbuf_len(kex->my),
1.1 markus 160: server_host_key_blob, sbloblen,
161: dh_client_pub,
1.20 markus 162: kex->dh->pub_key,
1.3 djm 163: shared_secret,
1.20 markus 164: hash, &hashlen)) != 0)
165: goto out;
1.1 markus 166:
167: /* save session id := H */
168: if (kex->session_id == NULL) {
1.3 djm 169: kex->session_id_len = hashlen;
1.20 markus 170: kex->session_id = malloc(kex->session_id_len);
171: if (kex->session_id == NULL) {
172: r = SSH_ERR_ALLOC_FAIL;
173: goto out;
174: }
1.1 markus 175: memcpy(kex->session_id, hash, kex->session_id_len);
176: }
177:
178: /* sign H */
1.23 ! markus 179: if ((r = kex->sign(server_host_private, server_host_public, &signature,
! 180: &slen, hash, hashlen, kex->hostkey_alg, ssh->compat)) < 0)
1.20 markus 181: goto out;
1.1 markus 182:
183: /* destroy_sensitive_data(); */
184:
185: /* send server hostkey, DH pubkey 'f' and singed H */
1.20 markus 186: if ((r = sshpkt_start(ssh, SSH2_MSG_KEXDH_REPLY)) != 0 ||
187: (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 ||
188: (r = sshpkt_put_bignum2(ssh, kex->dh->pub_key)) != 0 || /* f */
189: (r = sshpkt_put_string(ssh, signature, slen)) != 0 ||
190: (r = sshpkt_send(ssh)) != 0)
191: goto out;
192:
193: if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
194: r = kex_send_newkeys(ssh);
195: out:
196: explicit_bzero(hash, sizeof(hash));
197: DH_free(kex->dh);
198: kex->dh = NULL;
199: if (dh_client_pub)
200: BN_clear_free(dh_client_pub);
201: if (kbuf) {
202: explicit_bzero(kbuf, klen);
203: free(kbuf);
204: }
205: if (shared_secret)
206: BN_clear_free(shared_secret);
207: free(server_host_key_blob);
1.13 djm 208: free(signature);
1.20 markus 209: return r;
1.1 markus 210: }
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