Damien Miller | 0588beb | 2011-02-18 09:18:45 +1100 | [diff] [blame] | 1 | /* $OpenBSD: ssh-keysign.c,v 1.36 2011/02/16 00:31:14 djm Exp $ */ |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 2 | /* |
| 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 Miller | d783435 | 2006-08-05 12:39:39 +1000 | [diff] [blame] | 25 | |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 26 | #include "includes.h" |
Damien Miller | 03e2003 | 2006-03-15 11:16:59 +1100 | [diff] [blame] | 27 | |
Damien Miller | 57cf638 | 2006-07-10 21:13:46 +1000 | [diff] [blame] | 28 | #include <fcntl.h> |
Damien Miller | 6645e7a | 2006-03-15 14:42:54 +1100 | [diff] [blame] | 29 | #ifdef HAVE_PATHS_H |
Damien Miller | 03e2003 | 2006-03-15 11:16:59 +1100 | [diff] [blame] | 30 | #include <paths.h> |
Damien Miller | 6645e7a | 2006-03-15 14:42:54 +1100 | [diff] [blame] | 31 | #endif |
Damien Miller | 9f2abc4 | 2006-07-10 20:53:08 +1000 | [diff] [blame] | 32 | #include <pwd.h> |
Damien Miller | ded319c | 2006-09-01 15:38:36 +1000 | [diff] [blame] | 33 | #include <stdarg.h> |
Damien Miller | e7a1e5c | 2006-08-05 11:34:19 +1000 | [diff] [blame] | 34 | #include <stdlib.h> |
Damien Miller | e3476ed | 2006-07-24 14:13:33 +1000 | [diff] [blame] | 35 | #include <string.h> |
Damien Miller | e6b3b61 | 2006-07-24 14:01:23 +1000 | [diff] [blame] | 36 | #include <unistd.h> |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 37 | |
| 38 | #include <openssl/evp.h> |
Ben Lindstrom | 43ce2c8 | 2002-07-04 00:17:33 +0000 | [diff] [blame] | 39 | #include <openssl/rand.h> |
| 40 | #include <openssl/rsa.h> |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 41 | |
Damien Miller | d783435 | 2006-08-05 12:39:39 +1000 | [diff] [blame] | 42 | #include "xmalloc.h" |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 43 | #include "log.h" |
| 44 | #include "key.h" |
Ben Lindstrom | 5d35a2f | 2002-07-04 00:19:40 +0000 | [diff] [blame] | 45 | #include "ssh.h" |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 46 | #include "ssh2.h" |
| 47 | #include "misc.h" |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 48 | #include "buffer.h" |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 49 | #include "authfile.h" |
| 50 | #include "msg.h" |
| 51 | #include "canohost.h" |
| 52 | #include "pathnames.h" |
Ben Lindstrom | 5d35a2f | 2002-07-04 00:19:40 +0000 | [diff] [blame] | 53 | #include "readconf.h" |
Darren Tucker | 25f60a7 | 2004-08-15 17:23:34 +1000 | [diff] [blame] | 54 | #include "uidswap.h" |
Ben Lindstrom | 5d35a2f | 2002-07-04 00:19:40 +0000 | [diff] [blame] | 55 | |
Damien Miller | 20a8f97 | 2003-05-18 20:50:30 +1000 | [diff] [blame] | 56 | /* XXX readconf.c needs these */ |
| 57 | uid_t original_real_uid; |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 58 | |
Ben Lindstrom | 3545352 | 2002-06-07 14:37:00 +0000 | [diff] [blame] | 59 | extern char *__progname; |
Ben Lindstrom | 3545352 | 2002-06-07 14:37:00 +0000 | [diff] [blame] | 60 | |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 61 | static int |
| 62 | valid_request(struct passwd *pw, char *host, Key **ret, u_char *data, |
| 63 | u_int datalen) |
| 64 | { |
| 65 | Buffer b; |
Damien Miller | 703ced5 | 2003-04-09 20:50:26 +1000 | [diff] [blame] | 66 | Key *key = NULL; |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 67 | 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 Lindstrom | cb72e4f | 2002-06-21 00:41:51 +0000 | [diff] [blame] | 76 | |
Damien Miller | 603e68f | 2006-04-23 12:05:32 +1000 | [diff] [blame] | 77 | /* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */ |
Ben Lindstrom | a207157 | 2002-06-09 20:01:48 +0000 | [diff] [blame] | 78 | p = buffer_get_string(&b, &len); |
Damien Miller | 603e68f | 2006-04-23 12:05:32 +1000 | [diff] [blame] | 79 | if (len != 20 && len != 32) |
Ben Lindstrom | a207157 | 2002-06-09 20:01:48 +0000 | [diff] [blame] | 80 | fail++; |
| 81 | xfree(p); |
| 82 | |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 83 | 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 Lindstrom | cb72e4f | 2002-06-21 00:41:51 +0000 | [diff] [blame] | 121 | fail++; |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 122 | else if (strncasecmp(host, p, len - 1) != 0) |
Ben Lindstrom | cb72e4f | 2002-06-21 00:41:51 +0000 | [diff] [blame] | 123 | fail++; |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 124 | 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 Miller | fb1310e | 2004-01-21 11:02:50 +1100 | [diff] [blame] | 136 | buffer_free(&b); |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 137 | |
| 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 | |
| 148 | int |
| 149 | main(int argc, char **argv) |
| 150 | { |
| 151 | Buffer b; |
Ben Lindstrom | 5d35a2f | 2002-07-04 00:19:40 +0000 | [diff] [blame] | 152 | Options options; |
Damien Miller | 0588beb | 2011-02-18 09:18:45 +1100 | [diff] [blame] | 153 | #define NUM_KEYTYPES 3 |
| 154 | Key *keys[NUM_KEYTYPES], *key = NULL; |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 155 | struct passwd *pw; |
Damien Miller | 0588beb | 2011-02-18 09:18:45 +1100 | [diff] [blame] | 156 | int key_fd[NUM_KEYTYPES], i, found, version = 2, fd; |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 157 | u_char *signature, *data; |
| 158 | char *host; |
| 159 | u_int slen, dlen; |
Ben Lindstrom | 43ce2c8 | 2002-07-04 00:17:33 +0000 | [diff] [blame] | 160 | u_int32_t rnd[256]; |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 161 | |
Darren Tucker | ce321d8 | 2005-10-03 18:11:24 +1000 | [diff] [blame] | 162 | /* Ensure that stdin and stdout are connected */ |
| 163 | if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2) |
| 164 | exit(1); |
| 165 | /* Leave /dev/null fd iff it is attached to stderr */ |
| 166 | if (fd > 2) |
| 167 | close(fd); |
| 168 | |
Damien Miller | 0588beb | 2011-02-18 09:18:45 +1100 | [diff] [blame] | 169 | i = 0; |
| 170 | key_fd[i++] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY); |
| 171 | key_fd[i++] = open(_PATH_HOST_ECDSA_KEY_FILE, O_RDONLY); |
| 172 | key_fd[i++] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY); |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 173 | |
Darren Tucker | 34620d6 | 2004-08-29 16:32:59 +1000 | [diff] [blame] | 174 | original_real_uid = getuid(); /* XXX readconf.c needs this */ |
| 175 | if ((pw = getpwuid(original_real_uid)) == NULL) |
Darren Tucker | 25f60a7 | 2004-08-15 17:23:34 +1000 | [diff] [blame] | 176 | fatal("getpwuid failed"); |
| 177 | pw = pwcopy(pw); |
| 178 | |
| 179 | permanently_set_uid(pw); |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 180 | |
Ben Lindstrom | 5a6abda | 2002-06-09 19:41:48 +0000 | [diff] [blame] | 181 | seed_rng(); |
| 182 | arc4random_stir(); |
Ben Lindstrom | db41d23 | 2002-06-07 03:11:38 +0000 | [diff] [blame] | 183 | |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 184 | #ifdef DEBUG_SSH_KEYSIGN |
| 185 | log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0); |
Ben Lindstrom | cb72e4f | 2002-06-21 00:41:51 +0000 | [diff] [blame] | 186 | #endif |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 187 | |
Ben Lindstrom | 5d35a2f | 2002-07-04 00:19:40 +0000 | [diff] [blame] | 188 | /* verify that ssh-keysign is enabled by the admin */ |
Ben Lindstrom | 5d35a2f | 2002-07-04 00:19:40 +0000 | [diff] [blame] | 189 | initialize_options(&options); |
Damien Miller | 57a4476 | 2004-04-20 20:11:57 +1000 | [diff] [blame] | 190 | (void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options, 0); |
Ben Lindstrom | 5d35a2f | 2002-07-04 00:19:40 +0000 | [diff] [blame] | 191 | fill_default_options(&options); |
Ben Lindstrom | b6df73b | 2002-11-09 15:52:31 +0000 | [diff] [blame] | 192 | if (options.enable_ssh_keysign != 1) |
| 193 | fatal("ssh-keysign not enabled in %s", |
Ben Lindstrom | 5d35a2f | 2002-07-04 00:19:40 +0000 | [diff] [blame] | 194 | _PATH_HOST_CONFIG_FILE); |
| 195 | |
Damien Miller | 0588beb | 2011-02-18 09:18:45 +1100 | [diff] [blame] | 196 | for (i = found = 0; i < NUM_KEYTYPES; i++) { |
| 197 | if (key_fd[i] != -1) |
| 198 | found = 1; |
| 199 | } |
| 200 | if (found == 0) |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 201 | fatal("could not open any host key"); |
| 202 | |
Damien Miller | 4314c2b | 2010-09-10 11:12:09 +1000 | [diff] [blame] | 203 | OpenSSL_add_all_algorithms(); |
Ben Lindstrom | 43ce2c8 | 2002-07-04 00:17:33 +0000 | [diff] [blame] | 204 | for (i = 0; i < 256; i++) |
| 205 | rnd[i] = arc4random(); |
| 206 | RAND_seed(rnd, sizeof(rnd)); |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 207 | |
| 208 | found = 0; |
Damien Miller | 0588beb | 2011-02-18 09:18:45 +1100 | [diff] [blame] | 209 | for (i = 0; i < NUM_KEYTYPES; i++) { |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 210 | keys[i] = NULL; |
| 211 | if (key_fd[i] == -1) |
| 212 | continue; |
| 213 | keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC, |
| 214 | NULL, NULL); |
| 215 | close(key_fd[i]); |
| 216 | if (keys[i] != NULL) |
| 217 | found = 1; |
| 218 | } |
| 219 | if (!found) |
| 220 | fatal("no hostkey found"); |
| 221 | |
| 222 | buffer_init(&b); |
Damien Miller | 901119b | 2002-10-04 11:10:04 +1000 | [diff] [blame] | 223 | if (ssh_msg_recv(STDIN_FILENO, &b) < 0) |
| 224 | fatal("ssh_msg_recv failed"); |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 225 | if (buffer_get_char(&b) != version) |
| 226 | fatal("bad version"); |
| 227 | fd = buffer_get_int(&b); |
| 228 | if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO)) |
| 229 | fatal("bad fd"); |
| 230 | if ((host = get_local_name(fd)) == NULL) |
Darren Tucker | daaa450 | 2010-01-13 22:43:33 +1100 | [diff] [blame] | 231 | fatal("cannot get local name for fd"); |
Ben Lindstrom | cb72e4f | 2002-06-21 00:41:51 +0000 | [diff] [blame] | 232 | |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 233 | data = buffer_get_string(&b, &dlen); |
| 234 | if (valid_request(pw, host, &key, data, dlen) < 0) |
| 235 | fatal("not a valid request"); |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 236 | xfree(host); |
| 237 | |
| 238 | found = 0; |
Damien Miller | 0588beb | 2011-02-18 09:18:45 +1100 | [diff] [blame] | 239 | for (i = 0; i < NUM_KEYTYPES; i++) { |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 240 | if (keys[i] != NULL && |
Damien Miller | c158331 | 2010-08-05 13:04:50 +1000 | [diff] [blame] | 241 | key_equal_public(key, keys[i])) { |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 242 | found = 1; |
| 243 | break; |
| 244 | } |
| 245 | } |
| 246 | if (!found) |
| 247 | fatal("no matching hostkey found"); |
| 248 | |
| 249 | if (key_sign(keys[i], &signature, &slen, data, dlen) != 0) |
| 250 | fatal("key_sign failed"); |
Ben Lindstrom | fe27598 | 2002-06-27 00:25:07 +0000 | [diff] [blame] | 251 | xfree(data); |
Ben Lindstrom | cb72e4f | 2002-06-21 00:41:51 +0000 | [diff] [blame] | 252 | |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 253 | /* send reply */ |
| 254 | buffer_clear(&b); |
| 255 | buffer_put_string(&b, signature, slen); |
Damien Miller | 51bf11f | 2003-11-17 21:20:47 +1100 | [diff] [blame] | 256 | if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1) |
| 257 | fatal("ssh_msg_send failed"); |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 258 | |
| 259 | return (0); |
| 260 | } |