1 /* $OpenBSD: ssh-keysign.c,v 1.39 2013/12/06 13:39:49 markus 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.
38 #include <openssl/evp.h>
39 #include <openssl/rand.h>
40 #include <openssl/rsa.h>
41 #include <openssl/engine.h>
53 #include "pathnames.h"
57 /* XXX readconf.c needs these */
58 uid_t original_real_uid;
60 extern char *__progname;
63 valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
76 buffer_append(&b, data, datalen);
78 /* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */
79 p = buffer_get_string(&b, &len);
80 if (len != 20 && len != 32)
84 if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
88 buffer_skip_string(&b);
91 p = buffer_get_string(&b, NULL);
92 if (strcmp("ssh-connection", p) != 0)
97 p = buffer_get_string(&b, NULL);
98 if (strcmp("hostbased", p) != 0)
103 pkalg = buffer_get_string(&b, NULL);
104 pkblob = buffer_get_string(&b, &blen);
106 pktype = key_type_from_name(pkalg);
107 if (pktype == KEY_UNSPEC)
109 else if ((key = key_from_blob(pkblob, blen)) == NULL)
111 else if (key->type != pktype)
116 /* client host name, handle trailing dot */
117 p = buffer_get_string(&b, &len);
118 debug2("valid_request: check expect chost %s got %s", host, p);
119 if (strlen(host) != len - 1)
121 else if (p[len - 1] != '.')
123 else if (strncasecmp(host, p, len - 1) != 0)
128 p = buffer_get_string(&b, NULL);
130 if (strcmp(pw->pw_name, p) != 0)
135 if (buffer_len(&b) != 0)
139 debug3("valid_request: fail %d", fail);
141 if (fail && key != NULL)
146 return (fail ? -1 : 0);
150 main(int argc, char **argv)
154 #define NUM_KEYTYPES 4
155 Key *keys[NUM_KEYTYPES], *key = NULL;
157 int key_fd[NUM_KEYTYPES], i, found, version = 2, fd;
158 u_char *signature, *data;
163 /* Ensure that stdin and stdout are connected */
164 if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
166 /* Leave /dev/null fd iff it is attached to stderr */
171 key_fd[i++] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
172 key_fd[i++] = open(_PATH_HOST_ECDSA_KEY_FILE, O_RDONLY);
173 key_fd[i++] = open(_PATH_HOST_ED25519_KEY_FILE, O_RDONLY);
174 key_fd[i++] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
176 original_real_uid = getuid(); /* XXX readconf.c needs this */
177 if ((pw = getpwuid(original_real_uid)) == NULL)
178 fatal("getpwuid failed");
181 permanently_set_uid(pw);
185 #ifdef DEBUG_SSH_KEYSIGN
186 log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
189 /* verify that ssh-keysign is enabled by the admin */
190 initialize_options(&options);
191 (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, "", &options, 0);
192 fill_default_options(&options);
193 if (options.enable_ssh_keysign != 1)
194 fatal("ssh-keysign not enabled in %s",
195 _PATH_HOST_CONFIG_FILE);
197 for (i = found = 0; i < NUM_KEYTYPES; i++) {
202 fatal("could not open any host key");
204 OpenSSL_add_all_algorithms();
206 /* Init available hardware crypto engines. */
207 ENGINE_load_builtin_engines();
208 ENGINE_register_all_complete();
210 for (i = 0; i < 256; i++)
211 rnd[i] = arc4random();
212 RAND_seed(rnd, sizeof(rnd));
215 for (i = 0; i < NUM_KEYTYPES; i++) {
219 keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
226 fatal("no hostkey found");
229 if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
230 fatal("ssh_msg_recv failed");
231 if (buffer_get_char(&b) != version)
232 fatal("bad version");
233 fd = buffer_get_int(&b);
234 if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
236 if ((host = get_local_name(fd)) == NULL)
237 fatal("cannot get local name for fd");
239 data = buffer_get_string(&b, &dlen);
240 if (valid_request(pw, host, &key, data, dlen) < 0)
241 fatal("not a valid request");
245 for (i = 0; i < NUM_KEYTYPES; i++) {
246 if (keys[i] != NULL &&
247 key_equal_public(key, keys[i])) {
253 fatal("no matching hostkey found");
255 if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
256 fatal("key_sign failed");
261 buffer_put_string(&b, signature, slen);
262 if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1)
263 fatal("ssh_msg_send failed");