2 * Copyright (c) 2002 Markus Friedl. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 RCSID("$OpenBSD: ssh-keysign.c,v 1.19 2005/09/13 23:40:07 djm Exp $");
27 #include <openssl/evp.h>
28 #include <openssl/rand.h>
29 #include <openssl/rsa.h>
42 #include "pathnames.h"
46 /* XXX readconf.c needs these */
47 uid_t original_real_uid;
49 extern char *__progname;
52 valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
65 buffer_append(&b, data, datalen);
67 /* session id, currently limited to SHA1 (20 bytes) */
68 p = buffer_get_string(&b, &len);
73 if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
77 buffer_skip_string(&b);
80 p = buffer_get_string(&b, NULL);
81 if (strcmp("ssh-connection", p) != 0)
86 p = buffer_get_string(&b, NULL);
87 if (strcmp("hostbased", p) != 0)
92 pkalg = buffer_get_string(&b, NULL);
93 pkblob = buffer_get_string(&b, &blen);
95 pktype = key_type_from_name(pkalg);
96 if (pktype == KEY_UNSPEC)
98 else if ((key = key_from_blob(pkblob, blen)) == NULL)
100 else if (key->type != pktype)
105 /* client host name, handle trailing dot */
106 p = buffer_get_string(&b, &len);
107 debug2("valid_request: check expect chost %s got %s", host, p);
108 if (strlen(host) != len - 1)
110 else if (p[len - 1] != '.')
112 else if (strncasecmp(host, p, len - 1) != 0)
117 p = buffer_get_string(&b, NULL);
119 if (strcmp(pw->pw_name, p) != 0)
124 if (buffer_len(&b) != 0)
128 debug3("valid_request: fail %d", fail);
130 if (fail && key != NULL)
135 return (fail ? -1 : 0);
139 main(int argc, char **argv)
145 int key_fd[2], i, found, version = 2, fd;
146 u_char *signature, *data;
151 /* Ensure that stdin and stdout are connected */
152 if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
154 /* Leave /dev/null fd iff it is attached to stderr */
158 key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
159 key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
161 original_real_uid = getuid(); /* XXX readconf.c needs this */
162 if ((pw = getpwuid(original_real_uid)) == NULL)
163 fatal("getpwuid failed");
166 permanently_set_uid(pw);
172 #ifdef DEBUG_SSH_KEYSIGN
173 log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
176 /* verify that ssh-keysign is enabled by the admin */
177 initialize_options(&options);
178 (void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options, 0);
179 fill_default_options(&options);
180 if (options.enable_ssh_keysign != 1)
181 fatal("ssh-keysign not enabled in %s",
182 _PATH_HOST_CONFIG_FILE);
184 if (key_fd[0] == -1 && key_fd[1] == -1)
185 fatal("could not open any host key");
187 SSLeay_add_all_algorithms();
188 for (i = 0; i < 256; i++)
189 rnd[i] = arc4random();
190 RAND_seed(rnd, sizeof(rnd));
193 for (i = 0; i < 2; i++) {
197 keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
204 fatal("no hostkey found");
207 if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
208 fatal("ssh_msg_recv failed");
209 if (buffer_get_char(&b) != version)
210 fatal("bad version");
211 fd = buffer_get_int(&b);
212 if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
214 if ((host = get_local_name(fd)) == NULL)
215 fatal("cannot get sockname for fd");
217 data = buffer_get_string(&b, &dlen);
218 if (valid_request(pw, host, &key, data, dlen) < 0)
219 fatal("not a valid request");
223 for (i = 0; i < 2; i++) {
224 if (keys[i] != NULL &&
225 key_equal(key, keys[i])) {
231 fatal("no matching hostkey found");
233 if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
234 fatal("key_sign failed");
239 buffer_put_string(&b, signature, slen);
240 if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1)
241 fatal("ssh_msg_send failed");