Annotation of src/usr.bin/ssh/kexdhc.c, Revision 1.29
1.29 ! djm 1: /* $OpenBSD: kexdhc.c,v 1.28 2019/01/21 10:03:37 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:
1.9 deraadt 26: #include <sys/types.h>
1.12 djm 27:
28: #include <openssl/dh.h>
1.7 stevesk 29:
1.8 stevesk 30: #include <stdio.h>
1.7 stevesk 31: #include <string.h>
1.9 deraadt 32: #include <signal.h>
1.1 markus 33:
1.17 markus 34: #include "sshkey.h"
1.9 deraadt 35: #include "cipher.h"
1.17 markus 36: #include "digest.h"
1.27 djm 37: #include "dh.h"
1.1 markus 38: #include "kex.h"
39: #include "log.h"
40: #include "packet.h"
41: #include "ssh2.h"
1.17 markus 42: #include "dispatch.h"
43: #include "compat.h"
44: #include "ssherr.h"
45: #include "sshbuf.h"
1.1 markus 46:
1.20 markus 47: static int input_kex_dh(int, u_int32_t, struct ssh *);
1.17 markus 48:
49: int
50: kexdh_client(struct ssh *ssh)
1.1 markus 51: {
1.17 markus 52: struct kex *kex = ssh->kex;
53: int r;
1.23 djm 54: const BIGNUM *pub_key;
1.1 markus 55:
56: /* generate and send 'e', client DH public key */
1.27 djm 57: if ((r = kex_dh_keygen(kex)) != 0)
1.17 markus 58: goto out;
1.1 markus 59: debug("sending SSH2_MSG_KEXDH_INIT");
1.23 djm 60: DH_get0_key(kex->dh, &pub_key, NULL);
61: if ((r = sshpkt_start(ssh, SSH2_MSG_KEXDH_INIT)) != 0 ||
62: (r = sshpkt_put_bignum2(ssh, pub_key)) != 0 ||
1.17 markus 63: (r = sshpkt_send(ssh)) != 0)
64: goto out;
1.1 markus 65: #ifdef DEBUG_KEXDH
1.17 markus 66: DHparams_print_fp(stderr, kex->dh);
1.1 markus 67: fprintf(stderr, "pub= ");
1.23 djm 68: BN_print_fp(stderr, pub_key);
1.1 markus 69: fprintf(stderr, "\n");
70: #endif
71: debug("expecting SSH2_MSG_KEXDH_REPLY");
1.17 markus 72: ssh_dispatch_set(ssh, SSH2_MSG_KEXDH_REPLY, &input_kex_dh);
73: r = 0;
74: out:
75: return r;
76: }
1.1 markus 77:
1.17 markus 78: static int
1.20 markus 79: input_kex_dh(int type, u_int32_t seq, struct ssh *ssh)
1.17 markus 80: {
81: struct kex *kex = ssh->kex;
1.28 djm 82: BIGNUM *dh_server_pub = NULL;
1.23 djm 83: const BIGNUM *pub_key;
1.17 markus 84: struct sshkey *server_host_key = NULL;
1.28 djm 85: struct sshbuf *shared_secret = NULL;
86: u_char *server_host_key_blob = NULL, *signature = NULL;
1.17 markus 87: u_char hash[SSH_DIGEST_MAX_LENGTH];
1.28 djm 88: size_t slen, sbloblen, hashlen;
89: int r;
1.17 markus 90:
1.1 markus 91: /* key, cert */
1.17 markus 92: if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
93: &sbloblen)) != 0 ||
94: (r = sshkey_from_blob(server_host_key_blob, sbloblen,
95: &server_host_key)) != 0)
96: goto out;
1.29 ! djm 97: if ((r = kex_verify_host_key(ssh, server_host_key)) != 0)
1.17 markus 98: goto out;
1.25 djm 99: /* DH parameter f, server public DH key, signed H */
100: if ((r = sshpkt_get_bignum2(ssh, &dh_server_pub)) != 0 ||
1.17 markus 101: (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
102: (r = sshpkt_get_end(ssh)) != 0)
103: goto out;
1.28 djm 104: if ((shared_secret = sshbuf_new()) == NULL) {
1.17 markus 105: r = SSH_ERR_ALLOC_FAIL;
106: goto out;
107: }
1.28 djm 108: if ((r = kex_dh_compute_key(kex, dh_server_pub, shared_secret)) != 0)
1.17 markus 109: goto out;
1.1 markus 110:
111: /* calc and verify H */
1.23 djm 112: DH_get0_key(kex->dh, &pub_key, NULL);
1.17 markus 113: hashlen = sizeof(hash);
114: if ((r = kex_dh_hash(
1.19 djm 115: kex->hash_alg,
1.24 djm 116: kex->client_version,
117: kex->server_version,
1.17 markus 118: sshbuf_ptr(kex->my), sshbuf_len(kex->my),
119: sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
1.1 markus 120: server_host_key_blob, sbloblen,
1.23 djm 121: pub_key,
1.1 markus 122: dh_server_pub,
1.28 djm 123: sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
1.17 markus 124: hash, &hashlen)) != 0)
125: goto out;
1.1 markus 126:
1.17 markus 127: if ((r = sshkey_verify(server_host_key, signature, slen, hash, hashlen,
1.21 djm 128: kex->hostkey_alg, ssh->compat)) != 0)
1.17 markus 129: goto out;
1.1 markus 130:
1.28 djm 131: if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
1.17 markus 132: r = kex_send_newkeys(ssh);
133: out:
134: explicit_bzero(hash, sizeof(hash));
135: DH_free(kex->dh);
136: kex->dh = NULL;
1.22 jsing 137: BN_clear_free(dh_server_pub);
1.28 djm 138: sshbuf_free(shared_secret);
1.17 markus 139: sshkey_free(server_host_key);
140: free(server_host_key_blob);
141: free(signature);
142: return r;
1.1 markus 143: }
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