1 /* $OpenBSD: ssh-keysign.c,v 1.56 2018/11/23 05:08:07 djm 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>
43 #include "openbsd-compat/openssl-compat.h"
56 #include "pathnames.h"
62 extern char *__progname;
65 valid_request(struct passwd *pw, char *host, struct sshkey **ret,
66 u_char *data, size_t datalen)
69 struct sshkey *key = NULL;
80 if ((b = sshbuf_from(data, datalen)) == NULL)
81 fatal("%s: sshbuf_from failed", __func__);
83 /* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */
84 if ((r = sshbuf_get_string(b, NULL, &len)) != 0)
85 fatal("%s: buffer error: %s", __func__, ssh_err(r));
86 if (len != 20 && len != 32)
89 if ((r = sshbuf_get_u8(b, &type)) != 0)
90 fatal("%s: buffer error: %s", __func__, ssh_err(r));
91 if (type != SSH2_MSG_USERAUTH_REQUEST)
95 if ((r = sshbuf_skip_string(b)) != 0)
96 fatal("%s: buffer error: %s", __func__, ssh_err(r));
99 if ((r = sshbuf_get_cstring(b, &p, NULL)) != 0)
100 fatal("%s: buffer error: %s", __func__, ssh_err(r));
101 if (strcmp("ssh-connection", p) != 0)
106 if ((r = sshbuf_get_cstring(b, &p, NULL)) != 0)
107 fatal("%s: buffer error: %s", __func__, ssh_err(r));
108 if (strcmp("hostbased", p) != 0)
113 if ((r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 ||
114 (r = sshbuf_get_string(b, &pkblob, &blen)) != 0)
115 fatal("%s: buffer error: %s", __func__, ssh_err(r));
117 pktype = sshkey_type_from_name(pkalg);
118 if (pktype == KEY_UNSPEC)
120 else if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
121 error("%s: bad key blob: %s", __func__, ssh_err(r));
123 } else if (key->type != pktype)
128 /* client host name, handle trailing dot */
129 if ((r = sshbuf_get_cstring(b, &p, &len)) != 0)
130 fatal("%s: buffer error: %s", __func__, ssh_err(r));
131 debug2("%s: check expect chost %s got %s", __func__, host, p);
132 if (strlen(host) != len - 1)
134 else if (p[len - 1] != '.')
136 else if (strncasecmp(host, p, len - 1) != 0)
141 if ((r = sshbuf_get_cstring(b, &luser, NULL)) != 0)
142 fatal("%s: buffer error: %s", __func__, ssh_err(r));
144 if (strcmp(pw->pw_name, luser) != 0)
149 if (sshbuf_len(b) != 0)
153 debug3("%s: fail %d", __func__, fail);
157 else if (ret != NULL)
160 return (fail ? -1 : 0);
164 main(int argc, char **argv)
168 #define NUM_KEYTYPES 5
169 struct sshkey *keys[NUM_KEYTYPES], *key = NULL;
171 int r, key_fd[NUM_KEYTYPES], i, found, version = 2, fd;
172 u_char *signature, *data, rver;
176 ssh_malloc_init(); /* must be called before any mallocs */
177 if (pledge("stdio rpath getpw dns id", NULL) != 0)
178 fatal("%s: pledge: %s", __progname, strerror(errno));
180 /* Ensure that stdin and stdout are connected */
181 if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
183 /* Leave /dev/null fd iff it is attached to stderr */
188 /* XXX This really needs to read sshd_config for the paths */
189 key_fd[i++] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
190 key_fd[i++] = open(_PATH_HOST_ECDSA_KEY_FILE, O_RDONLY);
191 key_fd[i++] = open(_PATH_HOST_ED25519_KEY_FILE, O_RDONLY);
192 key_fd[i++] = open(_PATH_HOST_XMSS_KEY_FILE, O_RDONLY);
193 key_fd[i++] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
195 if ((pw = getpwuid(getuid())) == NULL)
196 fatal("getpwuid failed");
199 permanently_set_uid(pw);
203 #ifdef DEBUG_SSH_KEYSIGN
204 log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
207 /* verify that ssh-keysign is enabled by the admin */
208 initialize_options(&options);
209 (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, "", "",
211 fill_default_options(&options);
212 if (options.enable_ssh_keysign != 1)
213 fatal("ssh-keysign not enabled in %s",
214 _PATH_HOST_CONFIG_FILE);
216 for (i = found = 0; i < NUM_KEYTYPES; i++) {
221 fatal("could not open any host key");
224 for (i = 0; i < NUM_KEYTYPES; i++) {
228 r = sshkey_load_private_type_fd(key_fd[i], KEY_UNSPEC,
232 debug("parse key %d: %s", i, ssh_err(r));
233 else if (key != NULL) {
239 fatal("no hostkey found");
241 if (pledge("stdio dns", NULL) != 0)
242 fatal("%s: pledge: %s", __progname, strerror(errno));
244 if ((b = sshbuf_new()) == NULL)
245 fatal("%s: sshbuf_new failed", __progname);
246 if (ssh_msg_recv(STDIN_FILENO, b) < 0)
247 fatal("ssh_msg_recv failed");
248 if ((r = sshbuf_get_u8(b, &rver)) != 0)
249 fatal("%s: buffer error: %s", __progname, ssh_err(r));
251 fatal("bad version: received %d, expected %d", rver, version);
252 if ((r = sshbuf_get_u32(b, (u_int *)&fd)) != 0)
253 fatal("%s: buffer error: %s", __progname, ssh_err(r));
254 if (fd < 0 || fd == STDIN_FILENO || fd == STDOUT_FILENO)
256 if ((host = get_local_name(fd)) == NULL)
257 fatal("cannot get local name for fd");
259 if ((r = sshbuf_get_string(b, &data, &dlen)) != 0)
260 fatal("%s: buffer error: %s", __progname, ssh_err(r));
261 if (valid_request(pw, host, &key, data, dlen) < 0)
262 fatal("not a valid request");
266 for (i = 0; i < NUM_KEYTYPES; i++) {
267 if (keys[i] != NULL &&
268 sshkey_equal_public(key, keys[i])) {
274 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
275 SSH_FP_DEFAULT)) == NULL)
276 fatal("%s: sshkey_fingerprint failed", __progname);
277 fatal("no matching hostkey found for key %s %s",
278 sshkey_type(key), fp ? fp : "");
281 if ((r = sshkey_sign(keys[i], &signature, &slen, data, dlen, NULL, 0))
283 fatal("sshkey_sign failed: %s", ssh_err(r));
288 if ((r = sshbuf_put_string(b, signature, slen)) != 0)
289 fatal("%s: buffer error: %s", __progname, ssh_err(r));
290 if (ssh_msg_send(STDOUT_FILENO, version, b) == -1)
291 fatal("ssh_msg_send failed");