Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 1 | /* |
| 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" |
Darren Tucker | 0a4f04b | 2003-07-03 20:37:47 +1000 | [diff] [blame] | 25 | RCSID("$OpenBSD: ssh-keysign.c,v 1.13 2003/07/03 08:09:06 djm Exp $"); |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 26 | |
| 27 | #include <openssl/evp.h> |
Ben Lindstrom | 43ce2c8 | 2002-07-04 00:17:33 +0000 | [diff] [blame] | 28 | #include <openssl/rand.h> |
| 29 | #include <openssl/rsa.h> |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 30 | |
| 31 | #include "log.h" |
| 32 | #include "key.h" |
Ben Lindstrom | 5d35a2f | 2002-07-04 00:19:40 +0000 | [diff] [blame] | 33 | #include "ssh.h" |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 34 | #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 Lindstrom | 5d35a2f | 2002-07-04 00:19:40 +0000 | [diff] [blame] | 43 | #include "readconf.h" |
| 44 | |
Damien Miller | 20a8f97 | 2003-05-18 20:50:30 +1000 | [diff] [blame] | 45 | /* XXX readconf.c needs these */ |
| 46 | uid_t original_real_uid; |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 47 | |
Ben Lindstrom | 3545352 | 2002-06-07 14:37:00 +0000 | [diff] [blame] | 48 | #ifdef HAVE___PROGNAME |
| 49 | extern char *__progname; |
| 50 | #else |
| 51 | char *__progname; |
| 52 | #endif |
| 53 | |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 54 | static int |
| 55 | valid_request(struct passwd *pw, char *host, Key **ret, u_char *data, |
| 56 | u_int datalen) |
| 57 | { |
| 58 | Buffer b; |
Damien Miller | 703ced5 | 2003-04-09 20:50:26 +1000 | [diff] [blame] | 59 | Key *key = NULL; |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 60 | 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 Lindstrom | cb72e4f | 2002-06-21 00:41:51 +0000 | [diff] [blame] | 69 | |
Ben Lindstrom | a207157 | 2002-06-09 20:01:48 +0000 | [diff] [blame] | 70 | /* 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 Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 76 | 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 Lindstrom | cb72e4f | 2002-06-21 00:41:51 +0000 | [diff] [blame] | 114 | fail++; |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 115 | else if (strncasecmp(host, p, len - 1) != 0) |
Ben Lindstrom | cb72e4f | 2002-06-21 00:41:51 +0000 | [diff] [blame] | 116 | fail++; |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 117 | 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 | |
| 140 | int |
| 141 | main(int argc, char **argv) |
| 142 | { |
| 143 | Buffer b; |
Ben Lindstrom | 5d35a2f | 2002-07-04 00:19:40 +0000 | [diff] [blame] | 144 | Options options; |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 145 | 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 Lindstrom | 43ce2c8 | 2002-07-04 00:17:33 +0000 | [diff] [blame] | 151 | u_int32_t rnd[256]; |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 152 | |
| 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 Lindstrom | 5a6abda | 2002-06-09 19:41:48 +0000 | [diff] [blame] | 159 | init_rng(); |
| 160 | seed_rng(); |
| 161 | arc4random_stir(); |
Ben Lindstrom | db41d23 | 2002-06-07 03:11:38 +0000 | [diff] [blame] | 162 | |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 163 | #ifdef DEBUG_SSH_KEYSIGN |
| 164 | log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0); |
Ben Lindstrom | cb72e4f | 2002-06-21 00:41:51 +0000 | [diff] [blame] | 165 | #endif |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 166 | |
Ben Lindstrom | 5d35a2f | 2002-07-04 00:19:40 +0000 | [diff] [blame] | 167 | /* 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 Lindstrom | b6df73b | 2002-11-09 15:52:31 +0000 | [diff] [blame] | 172 | if (options.enable_ssh_keysign != 1) |
| 173 | fatal("ssh-keysign not enabled in %s", |
Ben Lindstrom | 5d35a2f | 2002-07-04 00:19:40 +0000 | [diff] [blame] | 174 | _PATH_HOST_CONFIG_FILE); |
| 175 | |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 176 | 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 Lindstrom | cb72e4f | 2002-06-21 00:41:51 +0000 | [diff] [blame] | 181 | pw = pwcopy(pw); |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 182 | |
| 183 | SSLeay_add_all_algorithms(); |
Ben Lindstrom | 43ce2c8 | 2002-07-04 00:17:33 +0000 | [diff] [blame] | 184 | for (i = 0; i < 256; i++) |
| 185 | rnd[i] = arc4random(); |
| 186 | RAND_seed(rnd, sizeof(rnd)); |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 187 | |
| 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 Miller | 901119b | 2002-10-04 11:10:04 +1000 | [diff] [blame] | 203 | if (ssh_msg_recv(STDIN_FILENO, &b) < 0) |
| 204 | fatal("ssh_msg_recv failed"); |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 205 | 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 Lindstrom | cb72e4f | 2002-06-21 00:41:51 +0000 | [diff] [blame] | 212 | |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 213 | data = buffer_get_string(&b, &dlen); |
| 214 | if (valid_request(pw, host, &key, data, dlen) < 0) |
| 215 | fatal("not a valid request"); |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 216 | 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 Lindstrom | fe27598 | 2002-06-27 00:25:07 +0000 | [diff] [blame] | 231 | xfree(data); |
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 | /* send reply */ |
| 234 | buffer_clear(&b); |
| 235 | buffer_put_string(&b, signature, slen); |
Damien Miller | 901119b | 2002-10-04 11:10:04 +1000 | [diff] [blame] | 236 | ssh_msg_send(STDOUT_FILENO, version, &b); |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 237 | |
| 238 | return (0); |
| 239 | } |