1 /* $OpenBSD: ssh-keysign.c,v 1.52 2016/02/15 09:47:49 dtucker 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.
40 #include <openssl/evp.h>
41 #include <openssl/rand.h>
42 #include <openssl/rsa.h>
55 #include "pathnames.h"
61 struct ssh *active_state = NULL; /* XXX needed for linking */
63 extern char *__progname;
65 /* XXX readconf.c needs these */
66 uid_t original_real_uid;
68 extern char *__progname;
71 valid_request(struct passwd *pw, char *host, struct sshkey **ret,
72 u_char *data, size_t datalen)
75 struct sshkey *key = NULL;
86 if ((b = sshbuf_from(data, datalen)) == NULL)
87 fatal("%s: sshbuf_from failed", __func__);
89 /* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */
90 if ((r = sshbuf_get_string(b, NULL, &len)) != 0)
91 fatal("%s: buffer error: %s", __func__, ssh_err(r));
92 if (len != 20 && len != 32)
95 if ((r = sshbuf_get_u8(b, &type)) != 0)
96 fatal("%s: buffer error: %s", __func__, ssh_err(r));
97 if (type != SSH2_MSG_USERAUTH_REQUEST)
101 if ((r = sshbuf_skip_string(b)) != 0)
102 fatal("%s: buffer error: %s", __func__, ssh_err(r));
105 if ((r = sshbuf_get_cstring(b, &p, NULL)) != 0)
106 fatal("%s: buffer error: %s", __func__, ssh_err(r));
107 if (strcmp("ssh-connection", p) != 0)
112 if ((r = sshbuf_get_cstring(b, &p, NULL)) != 0)
113 fatal("%s: buffer error: %s", __func__, ssh_err(r));
114 if (strcmp("hostbased", p) != 0)
119 if ((r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 ||
120 (r = sshbuf_get_string(b, &pkblob, &blen)) != 0)
121 fatal("%s: buffer error: %s", __func__, ssh_err(r));
123 pktype = sshkey_type_from_name(pkalg);
124 if (pktype == KEY_UNSPEC)
126 else if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
127 error("%s: bad key blob: %s", __func__, ssh_err(r));
129 } else if (key->type != pktype)
134 /* client host name, handle trailing dot */
135 if ((r = sshbuf_get_cstring(b, &p, &len)) != 0)
136 fatal("%s: buffer error: %s", __func__, ssh_err(r));
137 debug2("%s: check expect chost %s got %s", __func__, host, p);
138 if (strlen(host) != len - 1)
140 else if (p[len - 1] != '.')
142 else if (strncasecmp(host, p, len - 1) != 0)
147 if ((r = sshbuf_get_cstring(b, &luser, NULL)) != 0)
148 fatal("%s: buffer error: %s", __func__, ssh_err(r));
150 if (strcmp(pw->pw_name, luser) != 0)
155 if (sshbuf_len(b) != 0)
159 debug3("%s: fail %d", __func__, fail);
161 if (fail && key != NULL)
163 else if (ret != NULL)
166 return (fail ? -1 : 0);
170 main(int argc, char **argv)
174 #define NUM_KEYTYPES 4
175 struct sshkey *keys[NUM_KEYTYPES], *key = NULL;
177 int r, key_fd[NUM_KEYTYPES], i, found, version = 2, fd;
178 u_char *signature, *data, rver;
185 ssh_malloc_init(); /* must be called before any mallocs */
186 if (pledge("stdio rpath getpw dns id", NULL) != 0)
187 fatal("%s: pledge: %s", __progname, strerror(errno));
189 /* Ensure that stdin and stdout are connected */
190 if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
192 /* Leave /dev/null fd iff it is attached to stderr */
197 /* XXX This really needs to read sshd_config for the paths */
198 key_fd[i++] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
199 key_fd[i++] = open(_PATH_HOST_ECDSA_KEY_FILE, O_RDONLY);
200 key_fd[i++] = open(_PATH_HOST_ED25519_KEY_FILE, O_RDONLY);
201 key_fd[i++] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
203 original_real_uid = getuid(); /* XXX readconf.c needs this */
204 if ((pw = getpwuid(original_real_uid)) == NULL)
205 fatal("getpwuid failed");
208 permanently_set_uid(pw);
212 #ifdef DEBUG_SSH_KEYSIGN
213 log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
216 /* verify that ssh-keysign is enabled by the admin */
217 initialize_options(&options);
218 (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, "", "", &options, 0);
219 fill_default_options(&options);
220 if (options.enable_ssh_keysign != 1)
221 fatal("ssh-keysign not enabled in %s",
222 _PATH_HOST_CONFIG_FILE);
224 for (i = found = 0; i < NUM_KEYTYPES; i++) {
229 fatal("could not open any host key");
232 OpenSSL_add_all_algorithms();
233 arc4random_buf(rnd, sizeof(rnd));
234 RAND_seed(rnd, sizeof(rnd));
238 for (i = 0; i < NUM_KEYTYPES; i++) {
242 r = sshkey_load_private_type_fd(key_fd[i], KEY_UNSPEC,
246 debug("parse key %d: %s", i, ssh_err(r));
247 else if (key != NULL) {
253 fatal("no hostkey found");
255 if (pledge("stdio dns", NULL) != 0)
256 fatal("%s: pledge: %s", __progname, strerror(errno));
258 if ((b = sshbuf_new()) == NULL)
259 fatal("%s: sshbuf_new failed", __progname);
260 if (ssh_msg_recv(STDIN_FILENO, b) < 0)
261 fatal("ssh_msg_recv failed");
262 if ((r = sshbuf_get_u8(b, &rver)) != 0)
263 fatal("%s: buffer error: %s", __progname, ssh_err(r));
265 fatal("bad version: received %d, expected %d", rver, version);
266 if ((r = sshbuf_get_u32(b, (u_int *)&fd)) != 0)
267 fatal("%s: buffer error: %s", __progname, ssh_err(r));
268 if (fd < 0 || fd == STDIN_FILENO || fd == STDOUT_FILENO)
270 if ((host = get_local_name(fd)) == NULL)
271 fatal("cannot get local name for fd");
273 if ((r = sshbuf_get_string(b, &data, &dlen)) != 0)
274 fatal("%s: buffer error: %s", __progname, ssh_err(r));
275 if (valid_request(pw, host, &key, data, dlen) < 0)
276 fatal("not a valid request");
280 for (i = 0; i < NUM_KEYTYPES; i++) {
281 if (keys[i] != NULL &&
282 sshkey_equal_public(key, keys[i])) {
288 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
289 SSH_FP_DEFAULT)) == NULL)
290 fatal("%s: sshkey_fingerprint failed", __progname);
291 fatal("no matching hostkey found for key %s %s",
292 sshkey_type(key), fp ? fp : "");
295 if ((r = sshkey_sign(keys[i], &signature, &slen, data, dlen, NULL, 0))
297 fatal("sshkey_sign failed: %s", ssh_err(r));
302 if ((r = sshbuf_put_string(b, signature, slen)) != 0)
303 fatal("%s: buffer error: %s", __progname, ssh_err(r));
304 if (ssh_msg_send(STDOUT_FILENO, version, b) == -1)
305 fatal("ssh_msg_send failed");