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");