blob: b3db628c69c7bddb585461989a085507927e1335 [file] [log] [blame]
Ben Lindstrom1bad2562002-06-06 19:57:33 +00001/*
2 * Copyright (c) 2002 Markus Friedl. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 */
24#include "includes.h"
Damien Miller51bf11f2003-11-17 21:20:47 +110025RCSID("$OpenBSD: ssh-keysign.c,v 1.14 2003/11/17 09:45:39 djm Exp $");
Ben Lindstrom1bad2562002-06-06 19:57:33 +000026
27#include <openssl/evp.h>
Ben Lindstrom43ce2c82002-07-04 00:17:33 +000028#include <openssl/rand.h>
29#include <openssl/rsa.h>
Ben Lindstrom1bad2562002-06-06 19:57:33 +000030
31#include "log.h"
32#include "key.h"
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +000033#include "ssh.h"
Ben Lindstrom1bad2562002-06-06 19:57:33 +000034#include "ssh2.h"
35#include "misc.h"
36#include "xmalloc.h"
37#include "buffer.h"
38#include "bufaux.h"
39#include "authfile.h"
40#include "msg.h"
41#include "canohost.h"
42#include "pathnames.h"
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +000043#include "readconf.h"
44
Damien Miller20a8f972003-05-18 20:50:30 +100045/* XXX readconf.c needs these */
46uid_t original_real_uid;
Ben Lindstrom1bad2562002-06-06 19:57:33 +000047
Ben Lindstrom35453522002-06-07 14:37:00 +000048#ifdef HAVE___PROGNAME
49extern char *__progname;
50#else
51char *__progname;
52#endif
53
Ben Lindstrom1bad2562002-06-06 19:57:33 +000054static int
55valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
56 u_int datalen)
57{
58 Buffer b;
Damien Miller703ced52003-04-09 20:50:26 +100059 Key *key = NULL;
Ben Lindstrom1bad2562002-06-06 19:57:33 +000060 u_char *pkblob;
61 u_int blen, len;
62 char *pkalg, *p;
63 int pktype, fail;
64
65 fail = 0;
66
67 buffer_init(&b);
68 buffer_append(&b, data, datalen);
Ben Lindstromcb72e4f2002-06-21 00:41:51 +000069
Ben Lindstroma2071572002-06-09 20:01:48 +000070 /* session id, currently limited to SHA1 (20 bytes) */
71 p = buffer_get_string(&b, &len);
72 if (len != 20)
73 fail++;
74 xfree(p);
75
Ben Lindstrom1bad2562002-06-06 19:57:33 +000076 if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
77 fail++;
78
79 /* server user */
80 buffer_skip_string(&b);
81
82 /* service */
83 p = buffer_get_string(&b, NULL);
84 if (strcmp("ssh-connection", p) != 0)
85 fail++;
86 xfree(p);
87
88 /* method */
89 p = buffer_get_string(&b, NULL);
90 if (strcmp("hostbased", p) != 0)
91 fail++;
92 xfree(p);
93
94 /* pubkey */
95 pkalg = buffer_get_string(&b, NULL);
96 pkblob = buffer_get_string(&b, &blen);
97
98 pktype = key_type_from_name(pkalg);
99 if (pktype == KEY_UNSPEC)
100 fail++;
101 else if ((key = key_from_blob(pkblob, blen)) == NULL)
102 fail++;
103 else if (key->type != pktype)
104 fail++;
105 xfree(pkalg);
106 xfree(pkblob);
107
108 /* client host name, handle trailing dot */
109 p = buffer_get_string(&b, &len);
110 debug2("valid_request: check expect chost %s got %s", host, p);
111 if (strlen(host) != len - 1)
112 fail++;
113 else if (p[len - 1] != '.')
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000114 fail++;
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000115 else if (strncasecmp(host, p, len - 1) != 0)
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000116 fail++;
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000117 xfree(p);
118
119 /* local user */
120 p = buffer_get_string(&b, NULL);
121
122 if (strcmp(pw->pw_name, p) != 0)
123 fail++;
124 xfree(p);
125
126 /* end of message */
127 if (buffer_len(&b) != 0)
128 fail++;
129
130 debug3("valid_request: fail %d", fail);
131
132 if (fail && key != NULL)
133 key_free(key);
134 else
135 *ret = key;
136
137 return (fail ? -1 : 0);
138}
139
140int
141main(int argc, char **argv)
142{
143 Buffer b;
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +0000144 Options options;
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000145 Key *keys[2], *key;
146 struct passwd *pw;
147 int key_fd[2], i, found, version = 2, fd;
148 u_char *signature, *data;
149 char *host;
150 u_int slen, dlen;
Ben Lindstrom43ce2c82002-07-04 00:17:33 +0000151 u_int32_t rnd[256];
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000152
153 key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
154 key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
155
156 seteuid(getuid());
157 setuid(getuid());
158
Ben Lindstrom5a6abda2002-06-09 19:41:48 +0000159 init_rng();
160 seed_rng();
161 arc4random_stir();
Ben Lindstromdb41d232002-06-07 03:11:38 +0000162
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000163#ifdef DEBUG_SSH_KEYSIGN
164 log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000165#endif
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000166
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +0000167 /* verify that ssh-keysign is enabled by the admin */
168 original_real_uid = getuid(); /* XXX readconf.c needs this */
169 initialize_options(&options);
170 (void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options);
171 fill_default_options(&options);
Ben Lindstromb6df73b2002-11-09 15:52:31 +0000172 if (options.enable_ssh_keysign != 1)
173 fatal("ssh-keysign not enabled in %s",
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +0000174 _PATH_HOST_CONFIG_FILE);
175
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000176 if (key_fd[0] == -1 && key_fd[1] == -1)
177 fatal("could not open any host key");
178
179 if ((pw = getpwuid(getuid())) == NULL)
180 fatal("getpwuid failed");
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000181 pw = pwcopy(pw);
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000182
183 SSLeay_add_all_algorithms();
Ben Lindstrom43ce2c82002-07-04 00:17:33 +0000184 for (i = 0; i < 256; i++)
185 rnd[i] = arc4random();
186 RAND_seed(rnd, sizeof(rnd));
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000187
188 found = 0;
189 for (i = 0; i < 2; i++) {
190 keys[i] = NULL;
191 if (key_fd[i] == -1)
192 continue;
193 keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
194 NULL, NULL);
195 close(key_fd[i]);
196 if (keys[i] != NULL)
197 found = 1;
198 }
199 if (!found)
200 fatal("no hostkey found");
201
202 buffer_init(&b);
Damien Miller901119b2002-10-04 11:10:04 +1000203 if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
204 fatal("ssh_msg_recv failed");
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000205 if (buffer_get_char(&b) != version)
206 fatal("bad version");
207 fd = buffer_get_int(&b);
208 if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
209 fatal("bad fd");
210 if ((host = get_local_name(fd)) == NULL)
211 fatal("cannot get sockname for fd");
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000212
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000213 data = buffer_get_string(&b, &dlen);
214 if (valid_request(pw, host, &key, data, dlen) < 0)
215 fatal("not a valid request");
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000216 xfree(host);
217
218 found = 0;
219 for (i = 0; i < 2; i++) {
220 if (keys[i] != NULL &&
221 key_equal(key, keys[i])) {
222 found = 1;
223 break;
224 }
225 }
226 if (!found)
227 fatal("no matching hostkey found");
228
229 if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
230 fatal("key_sign failed");
Ben Lindstromfe275982002-06-27 00:25:07 +0000231 xfree(data);
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000232
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000233 /* send reply */
234 buffer_clear(&b);
235 buffer_put_string(&b, signature, slen);
Damien Miller51bf11f2003-11-17 21:20:47 +1100236 if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1)
237 fatal("ssh_msg_send failed");
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000238
239 return (0);
240}