Annotation of src/usr.bin/ssh/kexgexs.c, Revision 1.30
1.30 ! deraadt 1: /* $OpenBSD: kexgexs.c,v 1.29 2016/06/08 02:13:01 dtucker 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:
1.5 stevesk 27:
1.7 stevesk 28: #include <stdio.h>
1.5 stevesk 29: #include <string.h>
1.8 deraadt 30: #include <signal.h>
1.14 djm 31:
32: #include <openssl/dh.h>
1.1 markus 33:
1.21 markus 34: #include "sshkey.h"
1.8 deraadt 35: #include "cipher.h"
1.21 markus 36: #include "digest.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"
1.8 deraadt 43: #ifdef GSSAPI
44: #include "ssh-gss.h"
45: #endif
1.1 markus 46: #include "monitor_wrap.h"
1.21 markus 47: #include "dispatch.h"
48: #include "ssherr.h"
49: #include "sshbuf.h"
1.30 ! deraadt 50: #include "misc.h"
1.1 markus 51:
1.21 markus 52: static int input_kex_dh_gex_request(int, u_int32_t, void *);
53: static int input_kex_dh_gex_init(int, u_int32_t, void *);
54:
55: int
56: kexgex_server(struct ssh *ssh)
1.1 markus 57: {
1.21 markus 58: ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST,
59: &input_kex_dh_gex_request);
60: debug("expecting SSH2_MSG_KEX_DH_GEX_REQUEST");
61: return 0;
62: }
1.1 markus 63:
1.21 markus 64: static int
65: input_kex_dh_gex_request(int type, u_int32_t seq, void *ctxt)
66: {
67: struct ssh *ssh = ctxt;
68: struct kex *kex = ssh->kex;
69: int r;
70: u_int min = 0, max = 0, nbits = 0;
1.1 markus 71:
1.25 djm 72: debug("SSH2_MSG_KEX_DH_GEX_REQUEST received");
73: if ((r = sshpkt_get_u32(ssh, &min)) != 0 ||
74: (r = sshpkt_get_u32(ssh, &nbits)) != 0 ||
75: (r = sshpkt_get_u32(ssh, &max)) != 0 ||
76: (r = sshpkt_get_end(ssh)) != 0)
1.21 markus 77: goto out;
1.25 djm 78: kex->nbits = nbits;
79: kex->min = min;
80: kex->max = max;
1.30 ! deraadt 81: min = MAXIMUM(DH_GRP_MIN, min);
! 82: max = MINIMUM(DH_GRP_MAX, max);
! 83: nbits = MAXIMUM(DH_GRP_MIN, nbits);
! 84: nbits = MINIMUM(DH_GRP_MAX, nbits);
1.29 dtucker 85:
1.21 markus 86: if (kex->max < kex->min || kex->nbits < kex->min ||
1.29 dtucker 87: kex->max < kex->nbits || kex->max < DH_GRP_MIN) {
1.21 markus 88: r = SSH_ERR_DH_GEX_OUT_OF_RANGE;
89: goto out;
90: }
1.1 markus 91:
92: /* Contact privileged parent */
1.29 dtucker 93: kex->dh = PRIVSEP(choose_dh(min, nbits, max));
1.21 markus 94: if (kex->dh == NULL) {
1.29 dtucker 95: sshpkt_disconnect(ssh, "no matching DH grp found");
1.21 markus 96: r = SSH_ERR_ALLOC_FAIL;
97: goto out;
98: }
1.1 markus 99: debug("SSH2_MSG_KEX_DH_GEX_GROUP sent");
1.21 markus 100: if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_GROUP)) != 0 ||
101: (r = sshpkt_put_bignum2(ssh, kex->dh->p)) != 0 ||
102: (r = sshpkt_put_bignum2(ssh, kex->dh->g)) != 0 ||
103: (r = sshpkt_send(ssh)) != 0)
104: goto out;
1.1 markus 105:
1.21 markus 106: /* Compute our exchange value in parallel with the client */
107: if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0)
108: goto out;
1.1 markus 109:
110: debug("expecting SSH2_MSG_KEX_DH_GEX_INIT");
1.21 markus 111: ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_INIT, &input_kex_dh_gex_init);
112: r = 0;
113: out:
114: return r;
115: }
116:
117: static int
118: input_kex_dh_gex_init(int type, u_int32_t seq, void *ctxt)
119: {
120: struct ssh *ssh = ctxt;
121: struct kex *kex = ssh->kex;
122: BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
123: struct sshkey *server_host_public, *server_host_private;
124: u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL;
125: u_char hash[SSH_DIGEST_MAX_LENGTH];
126: size_t sbloblen, slen;
127: size_t klen = 0, hashlen;
128: int kout, r;
129:
130: if (kex->load_host_public_key == NULL ||
131: kex->load_host_private_key == NULL) {
132: r = SSH_ERR_INVALID_ARGUMENT;
133: goto out;
134: }
1.24 djm 135: server_host_public = kex->load_host_public_key(kex->hostkey_type,
136: kex->hostkey_nid, ssh);
137: server_host_private = kex->load_host_private_key(kex->hostkey_type,
138: kex->hostkey_nid, ssh);
1.22 djm 139: if (server_host_public == NULL) {
1.21 markus 140: r = SSH_ERR_NO_HOSTKEY_LOADED;
141: goto out;
142: }
1.1 markus 143:
144: /* key, cert */
1.21 markus 145: if ((dh_client_pub = BN_new()) == NULL) {
146: r = SSH_ERR_ALLOC_FAIL;
147: goto out;
148: }
149: if ((r = sshpkt_get_bignum2(ssh, dh_client_pub)) != 0 ||
150: (r = sshpkt_get_end(ssh)) != 0)
151: goto out;
1.1 markus 152:
153: #ifdef DEBUG_KEXDH
154: fprintf(stderr, "dh_client_pub= ");
155: BN_print_fp(stderr, dh_client_pub);
156: fprintf(stderr, "\n");
157: debug("bits %d", BN_num_bits(dh_client_pub));
158: #endif
159:
160: #ifdef DEBUG_KEXDH
1.21 markus 161: DHparams_print_fp(stderr, kex->dh);
1.1 markus 162: fprintf(stderr, "pub= ");
1.21 markus 163: BN_print_fp(stderr, kex->dh->pub_key);
1.1 markus 164: fprintf(stderr, "\n");
165: #endif
1.21 markus 166: if (!dh_pub_is_valid(kex->dh, dh_client_pub)) {
167: sshpkt_disconnect(ssh, "bad client public DH value");
168: r = SSH_ERR_MESSAGE_INCOMPLETE;
169: goto out;
170: }
1.1 markus 171:
1.21 markus 172: klen = DH_size(kex->dh);
173: if ((kbuf = malloc(klen)) == NULL ||
174: (shared_secret = BN_new()) == NULL) {
175: r = SSH_ERR_ALLOC_FAIL;
176: goto out;
177: }
178: if ((kout = DH_compute_key(kbuf, dh_client_pub, kex->dh)) < 0 ||
179: BN_bin2bn(kbuf, kout, shared_secret) == NULL) {
180: r = SSH_ERR_LIBCRYPTO_ERROR;
181: goto out;
182: }
1.1 markus 183: #ifdef DEBUG_KEXDH
184: dump_digest("shared secret", kbuf, kout);
185: #endif
1.21 markus 186: if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob,
187: &sbloblen)) != 0)
188: goto out;
1.2 djm 189: /* calc H */
1.21 markus 190: hashlen = sizeof(hash);
191: if ((r = kexgex_hash(
1.17 djm 192: kex->hash_alg,
1.1 markus 193: kex->client_version_string,
194: kex->server_version_string,
1.21 markus 195: sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
196: sshbuf_ptr(kex->my), sshbuf_len(kex->my),
1.1 markus 197: server_host_key_blob, sbloblen,
1.21 markus 198: kex->min, kex->nbits, kex->max,
199: kex->dh->p, kex->dh->g,
1.1 markus 200: dh_client_pub,
1.21 markus 201: kex->dh->pub_key,
1.2 djm 202: shared_secret,
1.21 markus 203: hash, &hashlen)) != 0)
204: goto out;
1.1 markus 205:
206: /* save session id := H */
207: if (kex->session_id == NULL) {
1.2 djm 208: kex->session_id_len = hashlen;
1.21 markus 209: kex->session_id = malloc(kex->session_id_len);
210: if (kex->session_id == NULL) {
211: r = SSH_ERR_ALLOC_FAIL;
212: goto out;
213: }
1.1 markus 214: memcpy(kex->session_id, hash, kex->session_id_len);
215: }
216:
217: /* sign H */
1.26 markus 218: if ((r = kex->sign(server_host_private, server_host_public, &signature,
219: &slen, hash, hashlen, kex->hostkey_alg, ssh->compat)) < 0)
1.21 markus 220: goto out;
1.1 markus 221:
222: /* destroy_sensitive_data(); */
223:
224: /* send server hostkey, DH pubkey 'f' and singed H */
1.21 markus 225: if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REPLY)) != 0 ||
226: (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 ||
227: (r = sshpkt_put_bignum2(ssh, kex->dh->pub_key)) != 0 || /* f */
228: (r = sshpkt_put_string(ssh, signature, slen)) != 0 ||
229: (r = sshpkt_send(ssh)) != 0)
230: goto out;
231:
232: if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
233: r = kex_send_newkeys(ssh);
234: out:
235: DH_free(kex->dh);
236: kex->dh = NULL;
237: if (dh_client_pub)
238: BN_clear_free(dh_client_pub);
239: if (kbuf) {
240: explicit_bzero(kbuf, klen);
241: free(kbuf);
242: }
243: if (shared_secret)
244: BN_clear_free(shared_secret);
245: free(server_host_key_blob);
1.15 djm 246: free(signature);
1.21 markus 247: return r;
1.1 markus 248: }
![[BACK]](/icons/back.gif){kind=icon}
Return to kexgexs.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh