Annotation of src/usr.bin/ssh/kexgexc.c, Revision 1.2.8.3
1.2.8.3 ! brad 1: /* $OpenBSD: kexgexc.c,v 1.11 2006/11/06 21:25:28 markus Exp $ */
1.1 markus 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:
1.2.8.2 brad 27: #include <sys/types.h>
28:
29: #include <stdio.h>
30: #include <string.h>
31: #include <signal.h>
1.1 markus 32:
33: #include "xmalloc.h"
1.2.8.2 brad 34: #include "buffer.h"
1.1 markus 35: #include "key.h"
1.2.8.2 brad 36: #include "cipher.h"
1.1 markus 37: #include "kex.h"
38: #include "log.h"
39: #include "packet.h"
40: #include "dh.h"
41: #include "ssh2.h"
42: #include "compat.h"
43:
44: void
45: kexgex_client(Kex *kex)
46: {
47: BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
48: BIGNUM *p = NULL, *g = NULL;
49: Key *server_host_key;
50: u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
1.2.8.3 ! brad 51: u_int klen, slen, sbloblen, hashlen;
! 52: int kout;
1.1 markus 53: int min, max, nbits;
54: DH *dh;
55:
56: nbits = dh_estimate(kex->we_need * 8);
57:
58: if (datafellows & SSH_OLD_DHGEX) {
59: /* Old GEX request */
60: packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST_OLD);
61: packet_put_int(nbits);
62: min = DH_GRP_MIN;
63: max = DH_GRP_MAX;
1.2 markus 64:
65: debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD(%u) sent", nbits);
1.1 markus 66: } else {
67: /* New GEX request */
68: min = DH_GRP_MIN;
69: max = DH_GRP_MAX;
70: packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
71: packet_put_int(min);
72: packet_put_int(nbits);
73: packet_put_int(max);
1.2 markus 74:
75: debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent",
76: min, nbits, max);
1.1 markus 77: }
78: #ifdef DEBUG_KEXDH
79: fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n",
80: min, nbits, max);
81: #endif
82: packet_send();
83:
84: debug("expecting SSH2_MSG_KEX_DH_GEX_GROUP");
85: packet_read_expect(SSH2_MSG_KEX_DH_GEX_GROUP);
86:
87: if ((p = BN_new()) == NULL)
88: fatal("BN_new");
89: packet_get_bignum2(p);
90: if ((g = BN_new()) == NULL)
91: fatal("BN_new");
92: packet_get_bignum2(g);
93: packet_check_eom();
94:
95: if (BN_num_bits(p) < min || BN_num_bits(p) > max)
96: fatal("DH_GEX group out of range: %d !< %d !< %d",
97: min, BN_num_bits(p), max);
98:
99: dh = dh_new_group(g, p);
100: dh_gen_key(dh, kex->we_need * 8);
101:
102: #ifdef DEBUG_KEXDH
103: DHparams_print_fp(stderr, dh);
104: fprintf(stderr, "pub= ");
105: BN_print_fp(stderr, dh->pub_key);
106: fprintf(stderr, "\n");
107: #endif
108:
109: debug("SSH2_MSG_KEX_DH_GEX_INIT sent");
110: /* generate and send 'e', client DH public key */
111: packet_start(SSH2_MSG_KEX_DH_GEX_INIT);
112: packet_put_bignum2(dh->pub_key);
113: packet_send();
114:
115: debug("expecting SSH2_MSG_KEX_DH_GEX_REPLY");
116: packet_read_expect(SSH2_MSG_KEX_DH_GEX_REPLY);
117:
118: /* key, cert */
119: server_host_key_blob = packet_get_string(&sbloblen);
120: server_host_key = key_from_blob(server_host_key_blob, sbloblen);
121: if (server_host_key == NULL)
122: fatal("cannot decode server_host_key_blob");
123: if (server_host_key->type != kex->hostkey_type)
124: fatal("type mismatch for decoded server_host_key_blob");
125: if (kex->verify_host_key == NULL)
126: fatal("cannot verify server_host_key");
127: if (kex->verify_host_key(server_host_key) == -1)
128: fatal("server_host_key verification failed");
129:
1.2.8.2 brad 130: /* DH parameter f, server public DH key */
1.1 markus 131: if ((dh_server_pub = BN_new()) == NULL)
132: fatal("dh_server_pub == NULL");
133: packet_get_bignum2(dh_server_pub);
134:
135: #ifdef DEBUG_KEXDH
136: fprintf(stderr, "dh_server_pub= ");
137: BN_print_fp(stderr, dh_server_pub);
138: fprintf(stderr, "\n");
139: debug("bits %d", BN_num_bits(dh_server_pub));
140: #endif
141:
142: /* signed H */
143: signature = packet_get_string(&slen);
144: packet_check_eom();
145:
146: if (!dh_pub_is_valid(dh, dh_server_pub))
147: packet_disconnect("bad server public DH value");
148:
149: klen = DH_size(dh);
150: kbuf = xmalloc(klen);
1.2.8.3 ! brad 151: if ((kout = DH_compute_key(kbuf, dh_server_pub, dh)) < 0)
! 152: fatal("DH_compute_key: failed");
1.1 markus 153: #ifdef DEBUG_KEXDH
154: dump_digest("shared secret", kbuf, kout);
155: #endif
156: if ((shared_secret = BN_new()) == NULL)
157: fatal("kexgex_client: BN_new failed");
1.2.8.3 ! brad 158: if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
! 159: fatal("kexgex_client: BN_bin2bn failed");
1.1 markus 160: memset(kbuf, 0, klen);
161: xfree(kbuf);
162:
163: if (datafellows & SSH_OLD_DHGEX)
164: min = max = -1;
165:
166: /* calc and verify H */
1.2.8.1 brad 167: kexgex_hash(
168: kex->evp_md,
1.1 markus 169: kex->client_version_string,
170: kex->server_version_string,
171: buffer_ptr(&kex->my), buffer_len(&kex->my),
172: buffer_ptr(&kex->peer), buffer_len(&kex->peer),
173: server_host_key_blob, sbloblen,
174: min, nbits, max,
175: dh->p, dh->g,
176: dh->pub_key,
177: dh_server_pub,
1.2.8.1 brad 178: shared_secret,
179: &hash, &hashlen
1.1 markus 180: );
1.2.8.1 brad 181:
1.1 markus 182: /* have keys, free DH */
183: DH_free(dh);
184: xfree(server_host_key_blob);
185: BN_clear_free(dh_server_pub);
186:
1.2.8.1 brad 187: if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
1.1 markus 188: fatal("key_verify failed for server_host_key");
189: key_free(server_host_key);
190: xfree(signature);
191:
192: /* save session id */
193: if (kex->session_id == NULL) {
1.2.8.1 brad 194: kex->session_id_len = hashlen;
1.1 markus 195: kex->session_id = xmalloc(kex->session_id_len);
196: memcpy(kex->session_id, hash, kex->session_id_len);
197: }
1.2.8.1 brad 198: kex_derive_keys(kex, hash, hashlen, shared_secret);
1.1 markus 199: BN_clear_free(shared_secret);
200:
201: kex_finish(kex);
202: }
![[BACK]](/icons/back.gif){kind=icon}
Return to kexgexc.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh