1 /* $OpenBSD: ssh-keysign.c,v 1.27 2006/07/22 20:48:23 stevesk Exp $ */
3 * Copyright (c) 2002 Markus Friedl. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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.
35 #include <openssl/evp.h>
36 #include <openssl/rand.h>
37 #include <openssl/rsa.h>
50 #include "pathnames.h"
54 /* XXX readconf.c needs these */
55 uid_t original_real_uid;
57 extern char *__progname;
60 valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
73 buffer_append(&b, data, datalen);
75 /* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */
76 p = buffer_get_string(&b, &len);
77 if (len != 20 && len != 32)
81 if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
85 buffer_skip_string(&b);
88 p = buffer_get_string(&b, NULL);
89 if (strcmp("ssh-connection", p) != 0)
94 p = buffer_get_string(&b, NULL);
95 if (strcmp("hostbased", p) != 0)
100 pkalg = buffer_get_string(&b, NULL);
101 pkblob = buffer_get_string(&b, &blen);
103 pktype = key_type_from_name(pkalg);
104 if (pktype == KEY_UNSPEC)
106 else if ((key = key_from_blob(pkblob, blen)) == NULL)
108 else if (key->type != pktype)
113 /* client host name, handle trailing dot */
114 p = buffer_get_string(&b, &len);
115 debug2("valid_request: check expect chost %s got %s", host, p);
116 if (strlen(host) != len - 1)
118 else if (p[len - 1] != '.')
120 else if (strncasecmp(host, p, len - 1) != 0)
125 p = buffer_get_string(&b, NULL);
127 if (strcmp(pw->pw_name, p) != 0)
132 if (buffer_len(&b) != 0)
136 debug3("valid_request: fail %d", fail);
138 if (fail && key != NULL)
143 return (fail ? -1 : 0);
147 main(int argc, char **argv)
151 Key *keys[2], *key = NULL;
153 int key_fd[2], i, found, version = 2, fd;
154 u_char *signature, *data;
159 /* Ensure that stdin and stdout are connected */
160 if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
162 /* Leave /dev/null fd iff it is attached to stderr */
166 key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
167 key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
169 original_real_uid = getuid(); /* XXX readconf.c needs this */
170 if ((pw = getpwuid(original_real_uid)) == NULL)
171 fatal("getpwuid failed");
174 permanently_set_uid(pw);
180 #ifdef DEBUG_SSH_KEYSIGN
181 log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
184 /* verify that ssh-keysign is enabled by the admin */
185 initialize_options(&options);
186 (void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options, 0);
187 fill_default_options(&options);
188 if (options.enable_ssh_keysign != 1)
189 fatal("ssh-keysign not enabled in %s",
190 _PATH_HOST_CONFIG_FILE);
192 if (key_fd[0] == -1 && key_fd[1] == -1)
193 fatal("could not open any host key");
195 SSLeay_add_all_algorithms();
196 for (i = 0; i < 256; i++)
197 rnd[i] = arc4random();
198 RAND_seed(rnd, sizeof(rnd));
201 for (i = 0; i < 2; i++) {
205 keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
212 fatal("no hostkey found");
215 if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
216 fatal("ssh_msg_recv failed");
217 if (buffer_get_char(&b) != version)
218 fatal("bad version");
219 fd = buffer_get_int(&b);
220 if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
222 if ((host = get_local_name(fd)) == NULL)
223 fatal("cannot get sockname for fd");
225 data = buffer_get_string(&b, &dlen);
226 if (valid_request(pw, host, &key, data, dlen) < 0)
227 fatal("not a valid request");
231 for (i = 0; i < 2; i++) {
232 if (keys[i] != NULL &&
233 key_equal(key, keys[i])) {
239 fatal("no matching hostkey found");
241 if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
242 fatal("key_sign failed");
247 buffer_put_string(&b, signature, slen);
248 if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1)
249 fatal("ssh_msg_send failed");