1 /* $OpenBSD: auth2-hostbased.c,v 1.14 2010/08/04 05:42:47 djm Exp $ */
3 * Copyright (c) 2000 Markus Friedl. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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.
28 #include <sys/types.h>
49 #include "monitor_wrap.h"
50 #include "pathnames.h"
53 extern ServerOptions options;
54 extern u_char *session_id2;
55 extern u_int session_id2_len;
58 userauth_hostbased(Authctxt *authctxt)
62 char *pkalg, *cuser, *chost, *service;
64 u_int alen, blen, slen;
66 int authenticated = 0;
68 if (!authctxt->valid) {
69 debug2("userauth_hostbased: disabled because of invalid user");
72 pkalg = packet_get_string(&alen);
73 pkblob = packet_get_string(&blen);
74 chost = packet_get_string(NULL);
75 cuser = packet_get_string(NULL);
76 sig = packet_get_string(&slen);
78 debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
79 cuser, chost, pkalg, slen);
83 buffer_append(&b, sig, slen);
87 pktype = key_type_from_name(pkalg);
88 if (pktype == KEY_UNSPEC) {
89 /* this is perfectly legal */
90 logit("userauth_hostbased: unsupported "
91 "public key algorithm: %s", pkalg);
94 key = key_from_blob(pkblob, blen);
96 error("userauth_hostbased: cannot decode key: %s", pkalg);
99 if (key->type != pktype) {
100 error("userauth_hostbased: type mismatch for decoded key "
101 "(received %d, expected %d)", key->type, pktype);
104 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
107 buffer_put_string(&b, session_id2, session_id2_len);
108 /* reconstruct packet */
109 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
110 buffer_put_cstring(&b, authctxt->user);
111 buffer_put_cstring(&b, service);
112 buffer_put_cstring(&b, "hostbased");
113 buffer_put_string(&b, pkalg, alen);
114 buffer_put_string(&b, pkblob, blen);
115 buffer_put_cstring(&b, chost);
116 buffer_put_cstring(&b, cuser);
120 /* test for allowed key and correct signature */
122 if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
123 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
124 buffer_len(&b))) == 1)
129 debug2("userauth_hostbased: authenticated %d", authenticated);
137 return authenticated;
140 /* return 1 if given hostkey is allowed */
142 hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
145 const char *resolvedname, *ipaddr, *lookup, *reason;
146 HostStatus host_status;
150 if (auth_key_is_revoked(key))
153 if (blacklisted_key(key)) {
154 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
155 if (options.permit_blacklisted_keys)
156 logit("Public key %s blacklisted (see "
157 "ssh-vulnkey(1)); continuing anyway", fp);
159 logit("Public key %s blacklisted (see "
160 "ssh-vulnkey(1))", fp);
162 if (!options.permit_blacklisted_keys)
166 resolvedname = get_canonical_hostname(options.use_dns);
167 ipaddr = get_remote_ipaddr();
169 debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s",
170 chost, resolvedname, ipaddr);
172 if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
173 debug2("stripping trailing dot from chost %s", chost);
174 chost[len - 1] = '\0';
177 if (options.hostbased_uses_name_from_packet_only) {
178 if (auth_rhosts2(pw, cuser, chost, chost) == 0)
182 if (strcasecmp(resolvedname, chost) != 0)
183 logit("userauth_hostbased mismatch: "
184 "client sends %s, but we resolve %s to %s",
185 chost, ipaddr, resolvedname);
186 if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0)
188 lookup = resolvedname;
190 debug2("userauth_hostbased: access allowed by auth_rhosts2");
192 if (key_is_cert(key) &&
193 key_cert_check_authority(key, 1, 0, lookup, &reason)) {
195 auth_debug_add("%s", reason);
199 host_status = check_key_in_hostfiles(pw, key, lookup,
200 _PATH_SSH_SYSTEM_HOSTFILE,
201 options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
203 /* backward compat if no key has been found. */
204 if (host_status == HOST_NEW) {
205 host_status = check_key_in_hostfiles(pw, key, lookup,
206 _PATH_SSH_SYSTEM_HOSTFILE2,
207 options.ignore_user_known_hosts ? NULL :
208 _PATH_SSH_USER_HOSTFILE2);
211 if (host_status == HOST_OK) {
212 if (key_is_cert(key)) {
213 fp = key_fingerprint(key->cert->signature_key,
214 SSH_FP_MD5, SSH_FP_HEX);
215 verbose("Accepted certificate ID \"%s\" signed by "
216 "%s CA %s from %s@%s", key->cert->key_id,
217 key_type(key->cert->signature_key), fp,
220 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
221 verbose("Accepted %s public key %s from %s@%s",
222 key_type(key), fp, cuser, lookup);
227 return (host_status == HOST_OK);
230 Authmethod method_hostbased = {
233 &options.hostbased_authentication