Annotation of src/crypto/external/bsd/openssh/dist/kexgexs.c, Revision 1.1.1.4
1.1.1.4 ! christos 1: /* $OpenBSD: kexgexs.c,v 1.14 2010/11/10 01:33:07 djm Exp $ */
1.1 christos 2: /*
3: * Copyright (c) 2000 Niels Provos. All rights reserved.
4: * Copyright (c) 2001 Markus Friedl. All rights reserved.
5: *
6: * Redistribution and use in source and binary forms, with or without
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/param.h>
28:
29: #include <stdio.h>
30: #include <string.h>
31: #include <signal.h>
32:
1.1.1.4 ! christos 33: #include <openssl/dh.h>
! 34:
1.1 christos 35: #include "xmalloc.h"
36: #include "buffer.h"
37: #include "key.h"
38: #include "cipher.h"
39: #include "kex.h"
40: #include "log.h"
41: #include "packet.h"
42: #include "dh.h"
43: #include "ssh2.h"
44: #include "compat.h"
45: #ifdef GSSAPI
46: #include "ssh-gss.h"
47: #endif
48: #include "monitor_wrap.h"
49:
50: void
51: kexgex_server(Kex *kex)
52: {
53: BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
1.1.1.3 adam 54: Key *server_host_public, *server_host_private;
1.1 christos 55: DH *dh;
56: u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
57: u_int sbloblen, klen, slen, hashlen;
58: int omin = -1, min = -1, omax = -1, max = -1, onbits = -1, nbits = -1;
59: int type, kout;
60:
1.1.1.3 adam 61: if (kex->load_host_public_key == NULL ||
62: kex->load_host_private_key == NULL)
1.1 christos 63: fatal("Cannot load hostkey");
1.1.1.3 adam 64: server_host_public = kex->load_host_public_key(kex->hostkey_type);
65: if (server_host_public == NULL)
1.1 christos 66: fatal("Unsupported hostkey type %d", kex->hostkey_type);
1.1.1.3 adam 67: server_host_private = kex->load_host_private_key(kex->hostkey_type);
68: if (server_host_private == NULL)
69: fatal("Missing private key for hostkey type %d",
70: kex->hostkey_type);
71:
1.1 christos 72:
73: type = packet_read();
74: switch (type) {
75: case SSH2_MSG_KEX_DH_GEX_REQUEST:
76: debug("SSH2_MSG_KEX_DH_GEX_REQUEST received");
77: omin = min = packet_get_int();
78: onbits = nbits = packet_get_int();
79: omax = max = packet_get_int();
80: min = MAX(DH_GRP_MIN, min);
81: max = MIN(DH_GRP_MAX, max);
82: nbits = MAX(DH_GRP_MIN, nbits);
83: nbits = MIN(DH_GRP_MAX, nbits);
84: break;
85: case SSH2_MSG_KEX_DH_GEX_REQUEST_OLD:
86: debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD received");
87: onbits = nbits = packet_get_int();
88: /* unused for old GEX */
89: omin = min = DH_GRP_MIN;
90: omax = max = DH_GRP_MAX;
91: break;
92: default:
93: fatal("protocol error during kex, no DH_GEX_REQUEST: %d", type);
94: }
95: packet_check_eom();
96:
97: if (omax < omin || onbits < omin || omax < onbits)
98: fatal("DH_GEX_REQUEST, bad parameters: %d !< %d !< %d",
99: omin, onbits, omax);
100:
101: /* Contact privileged parent */
102: dh = PRIVSEP(choose_dh(min, nbits, max));
103: if (dh == NULL)
104: packet_disconnect("Protocol error: no matching DH grp found");
105:
106: debug("SSH2_MSG_KEX_DH_GEX_GROUP sent");
107: packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
108: packet_put_bignum2(dh->p);
109: packet_put_bignum2(dh->g);
110: packet_send();
111:
112: /* flush */
113: packet_write_wait();
114:
115: /* Compute our exchange value in parallel with the client */
116: dh_gen_key(dh, kex->we_need * 8);
117:
118: debug("expecting SSH2_MSG_KEX_DH_GEX_INIT");
119: packet_read_expect(SSH2_MSG_KEX_DH_GEX_INIT);
120:
121: /* key, cert */
122: if ((dh_client_pub = BN_new()) == NULL)
123: fatal("dh_client_pub == NULL");
124: packet_get_bignum2(dh_client_pub);
125: packet_check_eom();
126:
127: #ifdef DEBUG_KEXDH
128: fprintf(stderr, "dh_client_pub= ");
129: BN_print_fp(stderr, dh_client_pub);
130: fprintf(stderr, "\n");
131: debug("bits %d", BN_num_bits(dh_client_pub));
132: #endif
133:
134: #ifdef DEBUG_KEXDH
135: DHparams_print_fp(stderr, dh);
136: fprintf(stderr, "pub= ");
137: BN_print_fp(stderr, dh->pub_key);
138: fprintf(stderr, "\n");
139: #endif
140: if (!dh_pub_is_valid(dh, dh_client_pub))
141: packet_disconnect("bad client public DH value");
142:
143: klen = DH_size(dh);
144: kbuf = xmalloc(klen);
145: if ((kout = DH_compute_key(kbuf, dh_client_pub, dh)) < 0)
146: fatal("DH_compute_key: failed");
147: #ifdef DEBUG_KEXDH
148: dump_digest("shared secret", kbuf, kout);
149: #endif
150: if ((shared_secret = BN_new()) == NULL)
151: fatal("kexgex_server: BN_new failed");
152: if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
153: fatal("kexgex_server: BN_bin2bn failed");
154: memset(kbuf, 0, klen);
155: xfree(kbuf);
156:
1.1.1.3 adam 157: key_to_blob(server_host_public, &server_host_key_blob, &sbloblen);
1.1 christos 158:
159: if (type == SSH2_MSG_KEX_DH_GEX_REQUEST_OLD)
160: omin = min = omax = max = -1;
161:
162: /* calc H */
163: kexgex_hash(
164: kex->evp_md,
165: kex->client_version_string,
166: kex->server_version_string,
167: buffer_ptr(&kex->peer), buffer_len(&kex->peer),
168: buffer_ptr(&kex->my), buffer_len(&kex->my),
169: server_host_key_blob, sbloblen,
170: omin, onbits, omax,
171: dh->p, dh->g,
172: dh_client_pub,
173: dh->pub_key,
174: shared_secret,
175: &hash, &hashlen
176: );
177: BN_clear_free(dh_client_pub);
178:
179: /* save session id := H */
180: if (kex->session_id == NULL) {
181: kex->session_id_len = hashlen;
182: kex->session_id = xmalloc(kex->session_id_len);
183: memcpy(kex->session_id, hash, kex->session_id_len);
184: }
185:
186: /* sign H */
1.1.1.3 adam 187: if (PRIVSEP(key_sign(server_host_private, &signature, &slen, hash,
1.1.1.2 christos 188: hashlen)) < 0)
189: fatal("kexgex_server: key_sign failed");
1.1 christos 190:
191: /* destroy_sensitive_data(); */
192:
193: /* send server hostkey, DH pubkey 'f' and singed H */
194: debug("SSH2_MSG_KEX_DH_GEX_REPLY sent");
195: packet_start(SSH2_MSG_KEX_DH_GEX_REPLY);
196: packet_put_string(server_host_key_blob, sbloblen);
197: packet_put_bignum2(dh->pub_key); /* f */
198: packet_put_string(signature, slen);
199: packet_send();
200:
201: xfree(signature);
202: xfree(server_host_key_blob);
203: /* have keys, free DH */
204: DH_free(dh);
205:
206: kex_derive_keys(kex, hash, hashlen, shared_secret);
207: BN_clear_free(shared_secret);
208:
209: kex_finish(kex);
210: }
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