1 /* $OpenBSD: auth2-hostbased.c,v 1.18 2014/07/15 15:54:14 millert 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 if (key_type_plain(key->type) == KEY_RSA &&
105 (datafellows & SSH_BUG_RSASIGMD5) != 0) {
106 error("Refusing RSA key because peer uses unsafe "
110 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
113 buffer_put_string(&b, session_id2, session_id2_len);
114 /* reconstruct packet */
115 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
116 buffer_put_cstring(&b, authctxt->user);
117 buffer_put_cstring(&b, service);
118 buffer_put_cstring(&b, "hostbased");
119 buffer_put_string(&b, pkalg, alen);
120 buffer_put_string(&b, pkblob, blen);
121 buffer_put_cstring(&b, chost);
122 buffer_put_cstring(&b, cuser);
127 pubkey_auth_info(authctxt, key,
128 "client user \"%.100s\", client host \"%.100s\"", cuser, chost);
130 /* test for allowed key and correct signature */
132 if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
133 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
134 buffer_len(&b))) == 1)
139 debug2("userauth_hostbased: authenticated %d", authenticated);
147 return authenticated;
150 /* return 1 if given hostkey is allowed */
152 hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
155 const char *resolvedname, *ipaddr, *lookup, *reason;
156 HostStatus host_status;
160 if (auth_key_is_revoked(key))
163 resolvedname = get_canonical_hostname(options.use_dns);
164 ipaddr = get_remote_ipaddr();
166 debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s",
167 chost, resolvedname, ipaddr);
169 if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
170 debug2("stripping trailing dot from chost %s", chost);
171 chost[len - 1] = '\0';
174 if (options.hostbased_uses_name_from_packet_only) {
175 if (auth_rhosts2(pw, cuser, chost, chost) == 0)
179 if (strcasecmp(resolvedname, chost) != 0)
180 logit("userauth_hostbased mismatch: "
181 "client sends %s, but we resolve %s to %s",
182 chost, ipaddr, resolvedname);
183 if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0)
185 lookup = resolvedname;
187 debug2("userauth_hostbased: access allowed by auth_rhosts2");
189 if (key_is_cert(key) &&
190 key_cert_check_authority(key, 1, 0, lookup, &reason)) {
192 auth_debug_add("%s", reason);
196 host_status = check_key_in_hostfiles(pw, key, lookup,
197 _PATH_SSH_SYSTEM_HOSTFILE,
198 options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
200 /* backward compat if no key has been found. */
201 if (host_status == HOST_NEW) {
202 host_status = check_key_in_hostfiles(pw, key, lookup,
203 _PATH_SSH_SYSTEM_HOSTFILE2,
204 options.ignore_user_known_hosts ? NULL :
205 _PATH_SSH_USER_HOSTFILE2);
208 if (host_status == HOST_OK) {
209 if (key_is_cert(key)) {
210 fp = key_fingerprint(key->cert->signature_key,
211 SSH_FP_MD5, SSH_FP_HEX);
212 verbose("Accepted certificate ID \"%s\" signed by "
213 "%s CA %s from %s@%s", key->cert->key_id,
214 key_type(key->cert->signature_key), fp,
217 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
218 verbose("Accepted %s public key %s from %s@%s",
219 key_type(key), fp, cuser, lookup);
224 return (host_status == HOST_OK);
227 Authmethod method_hostbased = {
230 &options.hostbased_authentication