blob: d05156005cf836243b2b49c1de1c6795ef32f96a [file] [log] [blame]
Damien Miller4314c2b2010-09-10 11:12:09 +10001/* $OpenBSD: ssh-keysign.c,v 1.35 2010/08/31 12:33:38 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 */
Damien Millerd7834352006-08-05 12:39:39 +100025
Ben Lindstrom1bad2562002-06-06 19:57:33 +000026#include "includes.h"
Damien Miller03e20032006-03-15 11:16:59 +110027
Damien Miller57cf6382006-07-10 21:13:46 +100028#include <fcntl.h>
Damien Miller6645e7a2006-03-15 14:42:54 +110029#ifdef HAVE_PATHS_H
Damien Miller03e20032006-03-15 11:16:59 +110030#include <paths.h>
Damien Miller6645e7a2006-03-15 14:42:54 +110031#endif
Damien Miller9f2abc42006-07-10 20:53:08 +100032#include <pwd.h>
Damien Millerded319c2006-09-01 15:38:36 +100033#include <stdarg.h>
Damien Millere7a1e5c2006-08-05 11:34:19 +100034#include <stdlib.h>
Damien Millere3476ed2006-07-24 14:13:33 +100035#include <string.h>
Damien Millere6b3b612006-07-24 14:01:23 +100036#include <unistd.h>
Ben Lindstrom1bad2562002-06-06 19:57:33 +000037
38#include <openssl/evp.h>
Ben Lindstrom43ce2c82002-07-04 00:17:33 +000039#include <openssl/rand.h>
40#include <openssl/rsa.h>
Ben Lindstrom1bad2562002-06-06 19:57:33 +000041
Damien Millerd7834352006-08-05 12:39:39 +100042#include "xmalloc.h"
Ben Lindstrom1bad2562002-06-06 19:57:33 +000043#include "log.h"
44#include "key.h"
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +000045#include "ssh.h"
Ben Lindstrom1bad2562002-06-06 19:57:33 +000046#include "ssh2.h"
47#include "misc.h"
Ben Lindstrom1bad2562002-06-06 19:57:33 +000048#include "buffer.h"
Ben Lindstrom1bad2562002-06-06 19:57:33 +000049#include "authfile.h"
50#include "msg.h"
51#include "canohost.h"
52#include "pathnames.h"
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +000053#include "readconf.h"
Darren Tucker25f60a72004-08-15 17:23:34 +100054#include "uidswap.h"
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +000055
Damien Miller20a8f972003-05-18 20:50:30 +100056/* XXX readconf.c needs these */
57uid_t original_real_uid;
Ben Lindstrom1bad2562002-06-06 19:57:33 +000058
Ben Lindstrom35453522002-06-07 14:37:00 +000059extern char *__progname;
Ben Lindstrom35453522002-06-07 14:37:00 +000060
Ben Lindstrom1bad2562002-06-06 19:57:33 +000061static int
62valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
63 u_int datalen)
64{
65 Buffer b;
Damien Miller703ced52003-04-09 20:50:26 +100066 Key *key = NULL;
Ben Lindstrom1bad2562002-06-06 19:57:33 +000067 u_char *pkblob;
68 u_int blen, len;
69 char *pkalg, *p;
70 int pktype, fail;
71
72 fail = 0;
73
74 buffer_init(&b);
75 buffer_append(&b, data, datalen);
Ben Lindstromcb72e4f2002-06-21 00:41:51 +000076
Damien Miller603e68f2006-04-23 12:05:32 +100077 /* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */
Ben Lindstroma2071572002-06-09 20:01:48 +000078 p = buffer_get_string(&b, &len);
Damien Miller603e68f2006-04-23 12:05:32 +100079 if (len != 20 && len != 32)
Ben Lindstroma2071572002-06-09 20:01:48 +000080 fail++;
81 xfree(p);
82
Ben Lindstrom1bad2562002-06-06 19:57:33 +000083 if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
84 fail++;
85
86 /* server user */
87 buffer_skip_string(&b);
88
89 /* service */
90 p = buffer_get_string(&b, NULL);
91 if (strcmp("ssh-connection", p) != 0)
92 fail++;
93 xfree(p);
94
95 /* method */
96 p = buffer_get_string(&b, NULL);
97 if (strcmp("hostbased", p) != 0)
98 fail++;
99 xfree(p);
100
101 /* pubkey */
102 pkalg = buffer_get_string(&b, NULL);
103 pkblob = buffer_get_string(&b, &blen);
104
105 pktype = key_type_from_name(pkalg);
106 if (pktype == KEY_UNSPEC)
107 fail++;
108 else if ((key = key_from_blob(pkblob, blen)) == NULL)
109 fail++;
110 else if (key->type != pktype)
111 fail++;
112 xfree(pkalg);
113 xfree(pkblob);
114
115 /* client host name, handle trailing dot */
116 p = buffer_get_string(&b, &len);
117 debug2("valid_request: check expect chost %s got %s", host, p);
118 if (strlen(host) != len - 1)
119 fail++;
120 else if (p[len - 1] != '.')
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000121 fail++;
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000122 else if (strncasecmp(host, p, len - 1) != 0)
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000123 fail++;
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000124 xfree(p);
125
126 /* local user */
127 p = buffer_get_string(&b, NULL);
128
129 if (strcmp(pw->pw_name, p) != 0)
130 fail++;
131 xfree(p);
132
133 /* end of message */
134 if (buffer_len(&b) != 0)
135 fail++;
Damien Millerfb1310e2004-01-21 11:02:50 +1100136 buffer_free(&b);
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000137
138 debug3("valid_request: fail %d", fail);
139
140 if (fail && key != NULL)
141 key_free(key);
142 else
143 *ret = key;
144
145 return (fail ? -1 : 0);
146}
147
148int
149main(int argc, char **argv)
150{
151 Buffer b;
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +0000152 Options options;
Damien Millerb8fe89c2006-07-24 14:51:00 +1000153 Key *keys[2], *key = NULL;
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000154 struct passwd *pw;
155 int key_fd[2], i, found, version = 2, fd;
156 u_char *signature, *data;
157 char *host;
158 u_int slen, dlen;
Ben Lindstrom43ce2c82002-07-04 00:17:33 +0000159 u_int32_t rnd[256];
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000160
Darren Tuckerce321d82005-10-03 18:11:24 +1000161 /* Ensure that stdin and stdout are connected */
162 if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
163 exit(1);
164 /* Leave /dev/null fd iff it is attached to stderr */
165 if (fd > 2)
166 close(fd);
167
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000168 key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
169 key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
170
Darren Tucker34620d62004-08-29 16:32:59 +1000171 original_real_uid = getuid(); /* XXX readconf.c needs this */
172 if ((pw = getpwuid(original_real_uid)) == NULL)
Darren Tucker25f60a72004-08-15 17:23:34 +1000173 fatal("getpwuid failed");
174 pw = pwcopy(pw);
175
176 permanently_set_uid(pw);
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000177
Ben Lindstrom5a6abda2002-06-09 19:41:48 +0000178 init_rng();
179 seed_rng();
180 arc4random_stir();
Ben Lindstromdb41d232002-06-07 03:11:38 +0000181
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000182#ifdef DEBUG_SSH_KEYSIGN
183 log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000184#endif
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000185
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +0000186 /* verify that ssh-keysign is enabled by the admin */
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +0000187 initialize_options(&options);
Damien Miller57a44762004-04-20 20:11:57 +1000188 (void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options, 0);
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +0000189 fill_default_options(&options);
Ben Lindstromb6df73b2002-11-09 15:52:31 +0000190 if (options.enable_ssh_keysign != 1)
191 fatal("ssh-keysign not enabled in %s",
Ben Lindstrom5d35a2f2002-07-04 00:19:40 +0000192 _PATH_HOST_CONFIG_FILE);
193
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000194 if (key_fd[0] == -1 && key_fd[1] == -1)
195 fatal("could not open any host key");
196
Damien Miller4314c2b2010-09-10 11:12:09 +1000197 OpenSSL_add_all_algorithms();
Ben Lindstrom43ce2c82002-07-04 00:17:33 +0000198 for (i = 0; i < 256; i++)
199 rnd[i] = arc4random();
200 RAND_seed(rnd, sizeof(rnd));
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000201
202 found = 0;
203 for (i = 0; i < 2; i++) {
204 keys[i] = NULL;
205 if (key_fd[i] == -1)
206 continue;
207 keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
208 NULL, NULL);
209 close(key_fd[i]);
210 if (keys[i] != NULL)
211 found = 1;
212 }
213 if (!found)
214 fatal("no hostkey found");
215
216 buffer_init(&b);
Damien Miller901119b2002-10-04 11:10:04 +1000217 if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
218 fatal("ssh_msg_recv failed");
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000219 if (buffer_get_char(&b) != version)
220 fatal("bad version");
221 fd = buffer_get_int(&b);
222 if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
223 fatal("bad fd");
224 if ((host = get_local_name(fd)) == NULL)
Darren Tuckerdaaa4502010-01-13 22:43:33 +1100225 fatal("cannot get local name for fd");
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000226
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000227 data = buffer_get_string(&b, &dlen);
228 if (valid_request(pw, host, &key, data, dlen) < 0)
229 fatal("not a valid request");
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000230 xfree(host);
231
232 found = 0;
233 for (i = 0; i < 2; i++) {
234 if (keys[i] != NULL &&
Damien Millerc1583312010-08-05 13:04:50 +1000235 key_equal_public(key, keys[i])) {
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000236 found = 1;
237 break;
238 }
239 }
240 if (!found)
241 fatal("no matching hostkey found");
242
243 if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
244 fatal("key_sign failed");
Ben Lindstromfe275982002-06-27 00:25:07 +0000245 xfree(data);
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000246
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000247 /* send reply */
248 buffer_clear(&b);
249 buffer_put_string(&b, signature, slen);
Damien Miller51bf11f2003-11-17 21:20:47 +1100250 if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1)
251 fatal("ssh_msg_send failed");
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000252
253 return (0);
254}