djm@openbsd.org | 1f729f0 | 2015-01-13 07:39:19 +0000 | [diff] [blame] | 1 | /* $OpenBSD: auth2-hostbased.c,v 1.22 2015/01/13 07:39:19 djm Exp $ */ |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 2 | /* |
| 3 | * Copyright (c) 2000 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 | |
| 26 | #include "includes.h" |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 27 | |
Damien Miller | 9f2abc4 | 2006-07-10 20:53:08 +1000 | [diff] [blame] | 28 | #include <sys/types.h> |
| 29 | |
| 30 | #include <pwd.h> |
Damien Miller | e3476ed | 2006-07-24 14:13:33 +1000 | [diff] [blame] | 31 | #include <string.h> |
Damien Miller | d783435 | 2006-08-05 12:39:39 +1000 | [diff] [blame] | 32 | #include <stdarg.h> |
Damien Miller | 9f2abc4 | 2006-07-10 20:53:08 +1000 | [diff] [blame] | 33 | |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 34 | #include "xmalloc.h" |
Damien Miller | d783435 | 2006-08-05 12:39:39 +1000 | [diff] [blame] | 35 | #include "ssh2.h" |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 36 | #include "packet.h" |
| 37 | #include "buffer.h" |
| 38 | #include "log.h" |
Damien Miller | 7acefbb | 2014-07-18 14:11:24 +1000 | [diff] [blame] | 39 | #include "misc.h" |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 40 | #include "servconf.h" |
| 41 | #include "compat.h" |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 42 | #include "key.h" |
Damien Miller | d783435 | 2006-08-05 12:39:39 +1000 | [diff] [blame] | 43 | #include "hostfile.h" |
| 44 | #include "auth.h" |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 45 | #include "canohost.h" |
Damien Miller | d783435 | 2006-08-05 12:39:39 +1000 | [diff] [blame] | 46 | #ifdef GSSAPI |
| 47 | #include "ssh-gss.h" |
| 48 | #endif |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 49 | #include "monitor_wrap.h" |
| 50 | #include "pathnames.h" |
djm@openbsd.org | 1f729f0 | 2015-01-13 07:39:19 +0000 | [diff] [blame] | 51 | #include "match.h" |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 52 | |
| 53 | /* import */ |
| 54 | extern ServerOptions options; |
| 55 | extern u_char *session_id2; |
Darren Tucker | 502d384 | 2003-06-28 12:38:01 +1000 | [diff] [blame] | 56 | extern u_int session_id2_len; |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 57 | |
| 58 | static int |
| 59 | userauth_hostbased(Authctxt *authctxt) |
| 60 | { |
| 61 | Buffer b; |
| 62 | Key *key = NULL; |
| 63 | char *pkalg, *cuser, *chost, *service; |
| 64 | u_char *pkblob, *sig; |
| 65 | u_int alen, blen, slen; |
| 66 | int pktype; |
| 67 | int authenticated = 0; |
| 68 | |
| 69 | if (!authctxt->valid) { |
| 70 | debug2("userauth_hostbased: disabled because of invalid user"); |
| 71 | return 0; |
| 72 | } |
| 73 | pkalg = packet_get_string(&alen); |
| 74 | pkblob = packet_get_string(&blen); |
| 75 | chost = packet_get_string(NULL); |
| 76 | cuser = packet_get_string(NULL); |
| 77 | sig = packet_get_string(&slen); |
| 78 | |
| 79 | debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d", |
| 80 | cuser, chost, pkalg, slen); |
| 81 | #ifdef DEBUG_PK |
| 82 | debug("signature:"); |
| 83 | buffer_init(&b); |
| 84 | buffer_append(&b, sig, slen); |
| 85 | buffer_dump(&b); |
| 86 | buffer_free(&b); |
| 87 | #endif |
djm@openbsd.org | 1195f4c | 2015-01-08 10:14:08 +0000 | [diff] [blame] | 88 | /* XXX provide some way to allow admin to specify key types accepted */ |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 89 | pktype = key_type_from_name(pkalg); |
| 90 | if (pktype == KEY_UNSPEC) { |
| 91 | /* this is perfectly legal */ |
Damien Miller | 996acd2 | 2003-04-09 20:59:48 +1000 | [diff] [blame] | 92 | logit("userauth_hostbased: unsupported " |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 93 | "public key algorithm: %s", pkalg); |
| 94 | goto done; |
| 95 | } |
| 96 | key = key_from_blob(pkblob, blen); |
| 97 | if (key == NULL) { |
| 98 | error("userauth_hostbased: cannot decode key: %s", pkalg); |
| 99 | goto done; |
| 100 | } |
| 101 | if (key->type != pktype) { |
| 102 | error("userauth_hostbased: type mismatch for decoded key " |
| 103 | "(received %d, expected %d)", key->type, pktype); |
| 104 | goto done; |
| 105 | } |
Damien Miller | 324541e | 2013-12-31 12:25:40 +1100 | [diff] [blame] | 106 | if (key_type_plain(key->type) == KEY_RSA && |
| 107 | (datafellows & SSH_BUG_RSASIGMD5) != 0) { |
| 108 | error("Refusing RSA key because peer uses unsafe " |
| 109 | "signature format"); |
| 110 | goto done; |
| 111 | } |
djm@openbsd.org | 1f729f0 | 2015-01-13 07:39:19 +0000 | [diff] [blame] | 112 | if (match_pattern_list(sshkey_ssh_name(key), |
| 113 | options.hostbased_key_types, |
| 114 | strlen(options.hostbased_key_types), 0) != 1) { |
| 115 | logit("%s: key type %s not in HostbasedAcceptedKeyTypes", |
| 116 | __func__, sshkey_type(key)); |
| 117 | goto done; |
| 118 | } |
| 119 | |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 120 | service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : |
| 121 | authctxt->service; |
| 122 | buffer_init(&b); |
| 123 | buffer_put_string(&b, session_id2, session_id2_len); |
| 124 | /* reconstruct packet */ |
| 125 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); |
| 126 | buffer_put_cstring(&b, authctxt->user); |
| 127 | buffer_put_cstring(&b, service); |
| 128 | buffer_put_cstring(&b, "hostbased"); |
| 129 | buffer_put_string(&b, pkalg, alen); |
| 130 | buffer_put_string(&b, pkblob, blen); |
| 131 | buffer_put_cstring(&b, chost); |
| 132 | buffer_put_cstring(&b, cuser); |
| 133 | #ifdef DEBUG_PK |
| 134 | buffer_dump(&b); |
| 135 | #endif |
Damien Miller | 20bdcd7 | 2013-07-18 16:10:09 +1000 | [diff] [blame] | 136 | |
| 137 | pubkey_auth_info(authctxt, key, |
| 138 | "client user \"%.100s\", client host \"%.100s\"", cuser, chost); |
| 139 | |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 140 | /* test for allowed key and correct signature */ |
| 141 | authenticated = 0; |
| 142 | if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) && |
| 143 | PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b), |
| 144 | buffer_len(&b))) == 1) |
| 145 | authenticated = 1; |
| 146 | |
Damien Miller | fb1310e | 2004-01-21 11:02:50 +1100 | [diff] [blame] | 147 | buffer_free(&b); |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 148 | done: |
| 149 | debug2("userauth_hostbased: authenticated %d", authenticated); |
| 150 | if (key != NULL) |
| 151 | key_free(key); |
Darren Tucker | a627d42 | 2013-06-02 07:31:17 +1000 | [diff] [blame] | 152 | free(pkalg); |
| 153 | free(pkblob); |
| 154 | free(cuser); |
| 155 | free(chost); |
| 156 | free(sig); |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 157 | return authenticated; |
| 158 | } |
| 159 | |
| 160 | /* return 1 if given hostkey is allowed */ |
| 161 | int |
| 162 | hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost, |
| 163 | Key *key) |
| 164 | { |
Damien Miller | c158331 | 2010-08-05 13:04:50 +1000 | [diff] [blame] | 165 | const char *resolvedname, *ipaddr, *lookup, *reason; |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 166 | HostStatus host_status; |
| 167 | int len; |
Damien Miller | c158331 | 2010-08-05 13:04:50 +1000 | [diff] [blame] | 168 | char *fp; |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 169 | |
Damien Miller | 1aed65e | 2010-03-04 21:53:35 +1100 | [diff] [blame] | 170 | if (auth_key_is_revoked(key)) |
| 171 | return 0; |
| 172 | |
Damien Miller | 3a961dc | 2003-06-03 10:25:48 +1000 | [diff] [blame] | 173 | resolvedname = get_canonical_hostname(options.use_dns); |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 174 | ipaddr = get_remote_ipaddr(); |
| 175 | |
djm@openbsd.org | 5191df9 | 2014-12-23 22:42:48 +0000 | [diff] [blame] | 176 | debug2("%s: chost %s resolvedname %s ipaddr %s", __func__, |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 177 | chost, resolvedname, ipaddr); |
| 178 | |
Damien Miller | a1d03a5 | 2008-07-17 18:57:19 +1000 | [diff] [blame] | 179 | if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') { |
| 180 | debug2("stripping trailing dot from chost %s", chost); |
| 181 | chost[len - 1] = '\0'; |
| 182 | } |
| 183 | |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 184 | if (options.hostbased_uses_name_from_packet_only) { |
djm@openbsd.org | 5191df9 | 2014-12-23 22:42:48 +0000 | [diff] [blame] | 185 | if (auth_rhosts2(pw, cuser, chost, chost) == 0) { |
| 186 | debug2("%s: auth_rhosts2 refused " |
| 187 | "user \"%.100s\" host \"%.100s\" (from packet)", |
| 188 | __func__, cuser, chost); |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 189 | return 0; |
djm@openbsd.org | 5191df9 | 2014-12-23 22:42:48 +0000 | [diff] [blame] | 190 | } |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 191 | lookup = chost; |
| 192 | } else { |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 193 | if (strcasecmp(resolvedname, chost) != 0) |
Damien Miller | 996acd2 | 2003-04-09 20:59:48 +1000 | [diff] [blame] | 194 | logit("userauth_hostbased mismatch: " |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 195 | "client sends %s, but we resolve %s to %s", |
| 196 | chost, ipaddr, resolvedname); |
djm@openbsd.org | 5191df9 | 2014-12-23 22:42:48 +0000 | [diff] [blame] | 197 | if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0) { |
| 198 | debug2("%s: auth_rhosts2 refused " |
| 199 | "user \"%.100s\" host \"%.100s\" addr \"%.100s\"", |
| 200 | __func__, cuser, resolvedname, ipaddr); |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 201 | return 0; |
djm@openbsd.org | 5191df9 | 2014-12-23 22:42:48 +0000 | [diff] [blame] | 202 | } |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 203 | lookup = resolvedname; |
| 204 | } |
djm@openbsd.org | 5191df9 | 2014-12-23 22:42:48 +0000 | [diff] [blame] | 205 | debug2("%s: access allowed by auth_rhosts2", __func__); |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 206 | |
Damien Miller | c158331 | 2010-08-05 13:04:50 +1000 | [diff] [blame] | 207 | if (key_is_cert(key) && |
| 208 | key_cert_check_authority(key, 1, 0, lookup, &reason)) { |
| 209 | error("%s", reason); |
| 210 | auth_debug_add("%s", reason); |
| 211 | return 0; |
| 212 | } |
| 213 | |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 214 | host_status = check_key_in_hostfiles(pw, key, lookup, |
| 215 | _PATH_SSH_SYSTEM_HOSTFILE, |
| 216 | options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE); |
| 217 | |
| 218 | /* backward compat if no key has been found. */ |
Damien Miller | c158331 | 2010-08-05 13:04:50 +1000 | [diff] [blame] | 219 | if (host_status == HOST_NEW) { |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 220 | host_status = check_key_in_hostfiles(pw, key, lookup, |
| 221 | _PATH_SSH_SYSTEM_HOSTFILE2, |
| 222 | options.ignore_user_known_hosts ? NULL : |
| 223 | _PATH_SSH_USER_HOSTFILE2); |
Damien Miller | c158331 | 2010-08-05 13:04:50 +1000 | [diff] [blame] | 224 | } |
| 225 | |
| 226 | if (host_status == HOST_OK) { |
| 227 | if (key_is_cert(key)) { |
| 228 | fp = key_fingerprint(key->cert->signature_key, |
djm@openbsd.org | 56d1c83 | 2014-12-21 22:27:55 +0000 | [diff] [blame] | 229 | options.fingerprint_hash, SSH_FP_DEFAULT); |
Damien Miller | c158331 | 2010-08-05 13:04:50 +1000 | [diff] [blame] | 230 | verbose("Accepted certificate ID \"%s\" signed by " |
| 231 | "%s CA %s from %s@%s", key->cert->key_id, |
| 232 | key_type(key->cert->signature_key), fp, |
| 233 | cuser, lookup); |
| 234 | } else { |
djm@openbsd.org | 56d1c83 | 2014-12-21 22:27:55 +0000 | [diff] [blame] | 235 | fp = key_fingerprint(key, options.fingerprint_hash, |
| 236 | SSH_FP_DEFAULT); |
Damien Miller | c158331 | 2010-08-05 13:04:50 +1000 | [diff] [blame] | 237 | verbose("Accepted %s public key %s from %s@%s", |
| 238 | key_type(key), fp, cuser, lookup); |
| 239 | } |
Darren Tucker | a627d42 | 2013-06-02 07:31:17 +1000 | [diff] [blame] | 240 | free(fp); |
Damien Miller | c158331 | 2010-08-05 13:04:50 +1000 | [diff] [blame] | 241 | } |
Ben Lindstrom | 855bf3a | 2002-06-06 20:27:55 +0000 | [diff] [blame] | 242 | |
| 243 | return (host_status == HOST_OK); |
| 244 | } |
| 245 | |
| 246 | Authmethod method_hostbased = { |
| 247 | "hostbased", |
| 248 | userauth_hostbased, |
| 249 | &options.hostbased_authentication |
| 250 | }; |