blob: 1f78c7a052638c503d12cbcc7249fa9d80299fac [file] [log] [blame]
Damien Miller57c30112006-03-26 14:24:48 +11001/* $OpenBSD: ssh-keysign.c,v 1.22 2006/03/25 13:17:02 djm Exp $ */
Ben Lindstrom1bad2562002-06-06 19:57:33 +00002/*
3 * Copyright (c) 2002 Markus Friedl. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
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.
13 *
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.
24 */
25#include "includes.h"
Damien Miller03e20032006-03-15 11:16:59 +110026
Damien Miller6645e7a2006-03-15 14:42:54 +110027#ifdef HAVE_PATHS_H
Damien Miller03e20032006-03-15 11:16:59 +110028#include <paths.h>
Damien Miller6645e7a2006-03-15 14:42:54 +110029#endif
Ben Lindstrom1bad2562002-06-06 19:57:33 +000030
31#include <openssl/evp.h>
Ben Lindstrom43ce2c82002-07-04 00:17:33 +000032#include <openssl/rand.h>
33#include <openssl/rsa.h>
Ben Lindstrom1bad2562002-06-06 19:57:33 +000034
35#include "log.h"
36#include "key.h"
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +000037#include "ssh.h"
Ben Lindstrom1bad2562002-06-06 19:57:33 +000038#include "ssh2.h"
39#include "misc.h"
40#include "xmalloc.h"
41#include "buffer.h"
42#include "bufaux.h"
43#include "authfile.h"
44#include "msg.h"
45#include "canohost.h"
46#include "pathnames.h"
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +000047#include "readconf.h"
Darren Tucker25f60a72004-08-15 17:23:34 +100048#include "uidswap.h"
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +000049
Damien Miller20a8f972003-05-18 20:50:30 +100050/* XXX readconf.c needs these */
51uid_t original_real_uid;
Ben Lindstrom1bad2562002-06-06 19:57:33 +000052
Ben Lindstrom35453522002-06-07 14:37:00 +000053extern char *__progname;
Ben Lindstrom35453522002-06-07 14:37:00 +000054
Ben Lindstrom1bad2562002-06-06 19:57:33 +000055static int
56valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
57 u_int datalen)
58{
59 Buffer b;
Damien Miller703ced52003-04-09 20:50:26 +100060 Key *key = NULL;
Ben Lindstrom1bad2562002-06-06 19:57:33 +000061 u_char *pkblob;
62 u_int blen, len;
63 char *pkalg, *p;
64 int pktype, fail;
65
66 fail = 0;
67
68 buffer_init(&b);
69 buffer_append(&b, data, datalen);
Ben Lindstromcb72e4f2002-06-21 00:41:51 +000070
Ben Lindstroma2071572002-06-09 20:01:48 +000071 /* session id, currently limited to SHA1 (20 bytes) */
72 p = buffer_get_string(&b, &len);
73 if (len != 20)
74 fail++;
75 xfree(p);
76
Ben Lindstrom1bad2562002-06-06 19:57:33 +000077 if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
78 fail++;
79
80 /* server user */
81 buffer_skip_string(&b);
82
83 /* service */
84 p = buffer_get_string(&b, NULL);
85 if (strcmp("ssh-connection", p) != 0)
86 fail++;
87 xfree(p);
88
89 /* method */
90 p = buffer_get_string(&b, NULL);
91 if (strcmp("hostbased", p) != 0)
92 fail++;
93 xfree(p);
94
95 /* pubkey */
96 pkalg = buffer_get_string(&b, NULL);
97 pkblob = buffer_get_string(&b, &blen);
98
99 pktype = key_type_from_name(pkalg);
100 if (pktype == KEY_UNSPEC)
101 fail++;
102 else if ((key = key_from_blob(pkblob, blen)) == NULL)
103 fail++;
104 else if (key->type != pktype)
105 fail++;
106 xfree(pkalg);
107 xfree(pkblob);
108
109 /* client host name, handle trailing dot */
110 p = buffer_get_string(&b, &len);
111 debug2("valid_request: check expect chost %s got %s", host, p);
112 if (strlen(host) != len - 1)
113 fail++;
114 else if (p[len - 1] != '.')
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000115 fail++;
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000116 else if (strncasecmp(host, p, len - 1) != 0)
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000117 fail++;
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000118 xfree(p);
119
120 /* local user */
121 p = buffer_get_string(&b, NULL);
122
123 if (strcmp(pw->pw_name, p) != 0)
124 fail++;
125 xfree(p);
126
127 /* end of message */
128 if (buffer_len(&b) != 0)
129 fail++;
Damien Millerfb1310e2004-01-21 11:02:50 +1100130 buffer_free(&b);
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000131
132 debug3("valid_request: fail %d", fail);
133
134 if (fail && key != NULL)
135 key_free(key);
136 else
137 *ret = key;
138
139 return (fail ? -1 : 0);
140}
141
142int
143main(int argc, char **argv)
144{
145 Buffer b;
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +0000146 Options options;
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000147 Key *keys[2], *key;
148 struct passwd *pw;
149 int key_fd[2], i, found, version = 2, fd;
150 u_char *signature, *data;
151 char *host;
152 u_int slen, dlen;
Ben Lindstrom43ce2c82002-07-04 00:17:33 +0000153 u_int32_t rnd[256];
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000154
Darren Tuckerce321d82005-10-03 18:11:24 +1000155 /* Ensure that stdin and stdout are connected */
156 if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
157 exit(1);
158 /* Leave /dev/null fd iff it is attached to stderr */
159 if (fd > 2)
160 close(fd);
161
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000162 key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
163 key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
164
Darren Tucker34620d62004-08-29 16:32:59 +1000165 original_real_uid = getuid(); /* XXX readconf.c needs this */
166 if ((pw = getpwuid(original_real_uid)) == NULL)
Darren Tucker25f60a72004-08-15 17:23:34 +1000167 fatal("getpwuid failed");
168 pw = pwcopy(pw);
169
170 permanently_set_uid(pw);
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000171
Ben Lindstrom5a6abda2002-06-09 19:41:48 +0000172 init_rng();
173 seed_rng();
174 arc4random_stir();
Ben Lindstromdb41d232002-06-07 03:11:38 +0000175
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000176#ifdef DEBUG_SSH_KEYSIGN
177 log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000178#endif
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000179
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +0000180 /* verify that ssh-keysign is enabled by the admin */
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +0000181 initialize_options(&options);
Damien Miller57a44762004-04-20 20:11:57 +1000182 (void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options, 0);
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +0000183 fill_default_options(&options);
Ben Lindstromb6df73b2002-11-09 15:52:31 +0000184 if (options.enable_ssh_keysign != 1)
185 fatal("ssh-keysign not enabled in %s",
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +0000186 _PATH_HOST_CONFIG_FILE);
187
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000188 if (key_fd[0] == -1 && key_fd[1] == -1)
189 fatal("could not open any host key");
190
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000191 SSLeay_add_all_algorithms();
Ben Lindstrom43ce2c82002-07-04 00:17:33 +0000192 for (i = 0; i < 256; i++)
193 rnd[i] = arc4random();
194 RAND_seed(rnd, sizeof(rnd));
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000195
196 found = 0;
197 for (i = 0; i < 2; i++) {
198 keys[i] = NULL;
199 if (key_fd[i] == -1)
200 continue;
201 keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
202 NULL, NULL);
203 close(key_fd[i]);
204 if (keys[i] != NULL)
205 found = 1;
206 }
207 if (!found)
208 fatal("no hostkey found");
209
210 buffer_init(&b);
Damien Miller901119b2002-10-04 11:10:04 +1000211 if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
212 fatal("ssh_msg_recv failed");
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000213 if (buffer_get_char(&b) != version)
214 fatal("bad version");
215 fd = buffer_get_int(&b);
216 if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
217 fatal("bad fd");
218 if ((host = get_local_name(fd)) == NULL)
219 fatal("cannot get sockname for fd");
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000220
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000221 data = buffer_get_string(&b, &dlen);
222 if (valid_request(pw, host, &key, data, dlen) < 0)
223 fatal("not a valid request");
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000224 xfree(host);
225
226 found = 0;
227 for (i = 0; i < 2; i++) {
228 if (keys[i] != NULL &&
229 key_equal(key, keys[i])) {
230 found = 1;
231 break;
232 }
233 }
234 if (!found)
235 fatal("no matching hostkey found");
236
237 if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
238 fatal("key_sign failed");
Ben Lindstromfe275982002-06-27 00:25:07 +0000239 xfree(data);
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000240
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000241 /* send reply */
242 buffer_clear(&b);
243 buffer_put_string(&b, signature, slen);
Damien Miller51bf11f2003-11-17 21:20:47 +1100244 if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1)
245 fatal("ssh_msg_send failed");
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000246
247 return (0);
248}