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" |
| 25 | RCSID("$OpenBSD: ssh-keysign.c,v 1.2 2002/05/31 10:30:33 markus Exp $"); |
| 26 | |
| 27 | #include <openssl/evp.h> |
| 28 | |
| 29 | #include "log.h" |
| 30 | #include "key.h" |
| 31 | #include "ssh2.h" |
| 32 | #include "misc.h" |
| 33 | #include "xmalloc.h" |
| 34 | #include "buffer.h" |
| 35 | #include "bufaux.h" |
| 36 | #include "authfile.h" |
| 37 | #include "msg.h" |
| 38 | #include "canohost.h" |
| 39 | #include "pathnames.h" |
| 40 | |
| 41 | static int |
| 42 | valid_request(struct passwd *pw, char *host, Key **ret, u_char *data, |
| 43 | u_int datalen) |
| 44 | { |
| 45 | Buffer b; |
| 46 | Key *key; |
| 47 | u_char *pkblob; |
| 48 | u_int blen, len; |
| 49 | char *pkalg, *p; |
| 50 | int pktype, fail; |
| 51 | |
| 52 | fail = 0; |
| 53 | |
| 54 | buffer_init(&b); |
| 55 | buffer_append(&b, data, datalen); |
| 56 | |
| 57 | /* session id */ |
| 58 | buffer_skip_string(&b); |
| 59 | if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST) |
| 60 | fail++; |
| 61 | |
| 62 | /* server user */ |
| 63 | buffer_skip_string(&b); |
| 64 | |
| 65 | /* service */ |
| 66 | p = buffer_get_string(&b, NULL); |
| 67 | if (strcmp("ssh-connection", p) != 0) |
| 68 | fail++; |
| 69 | xfree(p); |
| 70 | |
| 71 | /* method */ |
| 72 | p = buffer_get_string(&b, NULL); |
| 73 | if (strcmp("hostbased", p) != 0) |
| 74 | fail++; |
| 75 | xfree(p); |
| 76 | |
| 77 | /* pubkey */ |
| 78 | pkalg = buffer_get_string(&b, NULL); |
| 79 | pkblob = buffer_get_string(&b, &blen); |
| 80 | |
| 81 | pktype = key_type_from_name(pkalg); |
| 82 | if (pktype == KEY_UNSPEC) |
| 83 | fail++; |
| 84 | else if ((key = key_from_blob(pkblob, blen)) == NULL) |
| 85 | fail++; |
| 86 | else if (key->type != pktype) |
| 87 | fail++; |
| 88 | xfree(pkalg); |
| 89 | xfree(pkblob); |
| 90 | |
| 91 | /* client host name, handle trailing dot */ |
| 92 | p = buffer_get_string(&b, &len); |
| 93 | debug2("valid_request: check expect chost %s got %s", host, p); |
| 94 | if (strlen(host) != len - 1) |
| 95 | fail++; |
| 96 | else if (p[len - 1] != '.') |
| 97 | fail++; |
| 98 | else if (strncasecmp(host, p, len - 1) != 0) |
| 99 | fail++; |
| 100 | xfree(p); |
| 101 | |
| 102 | /* local user */ |
| 103 | p = buffer_get_string(&b, NULL); |
| 104 | |
| 105 | if (strcmp(pw->pw_name, p) != 0) |
| 106 | fail++; |
| 107 | xfree(p); |
| 108 | |
| 109 | /* end of message */ |
| 110 | if (buffer_len(&b) != 0) |
| 111 | fail++; |
| 112 | |
| 113 | debug3("valid_request: fail %d", fail); |
| 114 | |
| 115 | if (fail && key != NULL) |
| 116 | key_free(key); |
| 117 | else |
| 118 | *ret = key; |
| 119 | |
| 120 | return (fail ? -1 : 0); |
| 121 | } |
| 122 | |
| 123 | int |
| 124 | main(int argc, char **argv) |
| 125 | { |
| 126 | Buffer b; |
| 127 | Key *keys[2], *key; |
| 128 | struct passwd *pw; |
| 129 | int key_fd[2], i, found, version = 2, fd; |
| 130 | u_char *signature, *data; |
| 131 | char *host; |
| 132 | u_int slen, dlen; |
| 133 | |
| 134 | key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY); |
| 135 | key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY); |
| 136 | |
| 137 | seteuid(getuid()); |
| 138 | setuid(getuid()); |
| 139 | |
Ben Lindstrom | db41d23 | 2002-06-07 03:11:38 +0000 | [diff] [blame^] | 140 | init_rng(); |
| 141 | seed_rng(); |
| 142 | arc4random_stir(); |
| 143 | |
Ben Lindstrom | 1bad256 | 2002-06-06 19:57:33 +0000 | [diff] [blame] | 144 | #ifdef DEBUG_SSH_KEYSIGN |
| 145 | log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0); |
| 146 | #endif |
| 147 | |
| 148 | if (key_fd[0] == -1 && key_fd[1] == -1) |
| 149 | fatal("could not open any host key"); |
| 150 | |
| 151 | if ((pw = getpwuid(getuid())) == NULL) |
| 152 | fatal("getpwuid failed"); |
| 153 | pw = pwcopy(pw); |
| 154 | |
| 155 | SSLeay_add_all_algorithms(); |
| 156 | |
| 157 | found = 0; |
| 158 | for (i = 0; i < 2; i++) { |
| 159 | keys[i] = NULL; |
| 160 | if (key_fd[i] == -1) |
| 161 | continue; |
| 162 | keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC, |
| 163 | NULL, NULL); |
| 164 | close(key_fd[i]); |
| 165 | if (keys[i] != NULL) |
| 166 | found = 1; |
| 167 | } |
| 168 | if (!found) |
| 169 | fatal("no hostkey found"); |
| 170 | |
| 171 | buffer_init(&b); |
| 172 | if (msg_recv(STDIN_FILENO, &b) < 0) |
| 173 | fatal("msg_recv failed"); |
| 174 | if (buffer_get_char(&b) != version) |
| 175 | fatal("bad version"); |
| 176 | fd = buffer_get_int(&b); |
| 177 | if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO)) |
| 178 | fatal("bad fd"); |
| 179 | if ((host = get_local_name(fd)) == NULL) |
| 180 | fatal("cannot get sockname for fd"); |
| 181 | |
| 182 | data = buffer_get_string(&b, &dlen); |
| 183 | if (valid_request(pw, host, &key, data, dlen) < 0) |
| 184 | fatal("not a valid request"); |
| 185 | xfree(data); |
| 186 | xfree(host); |
| 187 | |
| 188 | found = 0; |
| 189 | for (i = 0; i < 2; i++) { |
| 190 | if (keys[i] != NULL && |
| 191 | key_equal(key, keys[i])) { |
| 192 | found = 1; |
| 193 | break; |
| 194 | } |
| 195 | } |
| 196 | if (!found) |
| 197 | fatal("no matching hostkey found"); |
| 198 | |
| 199 | if (key_sign(keys[i], &signature, &slen, data, dlen) != 0) |
| 200 | fatal("key_sign failed"); |
| 201 | |
| 202 | /* send reply */ |
| 203 | buffer_clear(&b); |
| 204 | buffer_put_string(&b, signature, slen); |
| 205 | msg_send(STDOUT_FILENO, version, &b); |
| 206 | |
| 207 | return (0); |
| 208 | } |