1 /* $OpenBSD: ssh-keysign.c,v 1.55 2018/07/27 05:34:42 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;
66 valid_request(struct passwd *pw, char *host, struct sshkey **ret,
67 u_char *data, size_t datalen)
70 struct sshkey *key = NULL;
81 if ((b = sshbuf_from(data, datalen)) == NULL)
82 fatal("%s: sshbuf_from failed", __func__);
84 /* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */
85 if ((r = sshbuf_get_string(b, NULL, &len)) != 0)
86 fatal("%s: buffer error: %s", __func__, ssh_err(r));
87 if (len != 20 && len != 32)
90 if ((r = sshbuf_get_u8(b, &type)) != 0)
91 fatal("%s: buffer error: %s", __func__, ssh_err(r));
92 if (type != SSH2_MSG_USERAUTH_REQUEST)
96 if ((r = sshbuf_skip_string(b)) != 0)
97 fatal("%s: buffer error: %s", __func__, ssh_err(r));
100 if ((r = sshbuf_get_cstring(b, &p, NULL)) != 0)
101 fatal("%s: buffer error: %s", __func__, ssh_err(r));
102 if (strcmp("ssh-connection", p) != 0)
107 if ((r = sshbuf_get_cstring(b, &p, NULL)) != 0)
108 fatal("%s: buffer error: %s", __func__, ssh_err(r));
109 if (strcmp("hostbased", p) != 0)
114 if ((r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 ||
115 (r = sshbuf_get_string(b, &pkblob, &blen)) != 0)
116 fatal("%s: buffer error: %s", __func__, ssh_err(r));
118 pktype = sshkey_type_from_name(pkalg);
119 if (pktype == KEY_UNSPEC)
121 else if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
122 error("%s: bad key blob: %s", __func__, ssh_err(r));
124 } else if (key->type != pktype)
129 /* client host name, handle trailing dot */
130 if ((r = sshbuf_get_cstring(b, &p, &len)) != 0)
131 fatal("%s: buffer error: %s", __func__, ssh_err(r));
132 debug2("%s: check expect chost %s got %s", __func__, host, p);
133 if (strlen(host) != len - 1)
135 else if (p[len - 1] != '.')
137 else if (strncasecmp(host, p, len - 1) != 0)
142 if ((r = sshbuf_get_cstring(b, &luser, NULL)) != 0)
143 fatal("%s: buffer error: %s", __func__, ssh_err(r));
145 if (strcmp(pw->pw_name, luser) != 0)
150 if (sshbuf_len(b) != 0)
154 debug3("%s: fail %d", __func__, fail);
158 else if (ret != NULL)
161 return (fail ? -1 : 0);
165 main(int argc, char **argv)
169 #define NUM_KEYTYPES 5
170 struct sshkey *keys[NUM_KEYTYPES], *key = NULL;
172 int r, key_fd[NUM_KEYTYPES], i, found, version = 2, fd;
173 u_char *signature, *data, rver;
180 ssh_malloc_init(); /* must be called before any mallocs */
181 if (pledge("stdio rpath getpw dns id", NULL) != 0)
182 fatal("%s: pledge: %s", __progname, strerror(errno));
184 /* Ensure that stdin and stdout are connected */
185 if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
187 /* Leave /dev/null fd iff it is attached to stderr */
192 /* XXX This really needs to read sshd_config for the paths */
193 key_fd[i++] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
194 key_fd[i++] = open(_PATH_HOST_ECDSA_KEY_FILE, O_RDONLY);
195 key_fd[i++] = open(_PATH_HOST_ED25519_KEY_FILE, O_RDONLY);
196 key_fd[i++] = open(_PATH_HOST_XMSS_KEY_FILE, O_RDONLY);
197 key_fd[i++] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
199 if ((pw = getpwuid(getuid())) == NULL)
200 fatal("getpwuid failed");
203 permanently_set_uid(pw);
207 #ifdef DEBUG_SSH_KEYSIGN
208 log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
211 /* verify that ssh-keysign is enabled by the admin */
212 initialize_options(&options);
213 (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, "", "", &options, 0);
214 fill_default_options(&options);
215 if (options.enable_ssh_keysign != 1)
216 fatal("ssh-keysign not enabled in %s",
217 _PATH_HOST_CONFIG_FILE);
219 for (i = found = 0; i < NUM_KEYTYPES; i++) {
224 fatal("could not open any host key");
227 OpenSSL_add_all_algorithms();
228 arc4random_buf(rnd, sizeof(rnd));
229 RAND_seed(rnd, sizeof(rnd));
233 for (i = 0; i < NUM_KEYTYPES; i++) {
237 r = sshkey_load_private_type_fd(key_fd[i], KEY_UNSPEC,
241 debug("parse key %d: %s", i, ssh_err(r));
242 else if (key != NULL) {
248 fatal("no hostkey found");
250 if (pledge("stdio dns", NULL) != 0)
251 fatal("%s: pledge: %s", __progname, strerror(errno));
253 if ((b = sshbuf_new()) == NULL)
254 fatal("%s: sshbuf_new failed", __progname);
255 if (ssh_msg_recv(STDIN_FILENO, b) < 0)
256 fatal("ssh_msg_recv failed");
257 if ((r = sshbuf_get_u8(b, &rver)) != 0)
258 fatal("%s: buffer error: %s", __progname, ssh_err(r));
260 fatal("bad version: received %d, expected %d", rver, version);
261 if ((r = sshbuf_get_u32(b, (u_int *)&fd)) != 0)
262 fatal("%s: buffer error: %s", __progname, ssh_err(r));
263 if (fd < 0 || fd == STDIN_FILENO || fd == STDOUT_FILENO)
265 if ((host = get_local_name(fd)) == NULL)
266 fatal("cannot get local name for fd");
268 if ((r = sshbuf_get_string(b, &data, &dlen)) != 0)
269 fatal("%s: buffer error: %s", __progname, ssh_err(r));
270 if (valid_request(pw, host, &key, data, dlen) < 0)
271 fatal("not a valid request");
275 for (i = 0; i < NUM_KEYTYPES; i++) {
276 if (keys[i] != NULL &&
277 sshkey_equal_public(key, keys[i])) {
283 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
284 SSH_FP_DEFAULT)) == NULL)
285 fatal("%s: sshkey_fingerprint failed", __progname);
286 fatal("no matching hostkey found for key %s %s",
287 sshkey_type(key), fp ? fp : "");
290 if ((r = sshkey_sign(keys[i], &signature, &slen, data, dlen, NULL, 0))
292 fatal("sshkey_sign failed: %s", ssh_err(r));
297 if ((r = sshbuf_put_string(b, signature, slen)) != 0)
298 fatal("%s: buffer error: %s", __progname, ssh_err(r));
299 if (ssh_msg_send(STDOUT_FILENO, version, b) == -1)
300 fatal("ssh_msg_send failed");