1 /* $OpenBSD: auth2-hostbased.c,v 1.9 2006/07/06 16:03:53 stevesk 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>
43 #include "monitor_wrap.h"
44 #include "pathnames.h"
47 extern ServerOptions options;
48 extern u_char *session_id2;
49 extern u_int session_id2_len;
52 userauth_hostbased(Authctxt *authctxt)
56 char *pkalg, *cuser, *chost, *service;
58 u_int alen, blen, slen;
60 int authenticated = 0;
62 if (!authctxt->valid) {
63 debug2("userauth_hostbased: disabled because of invalid user");
66 pkalg = packet_get_string(&alen);
67 pkblob = packet_get_string(&blen);
68 chost = packet_get_string(NULL);
69 cuser = packet_get_string(NULL);
70 sig = packet_get_string(&slen);
72 debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
73 cuser, chost, pkalg, slen);
77 buffer_append(&b, sig, slen);
81 pktype = key_type_from_name(pkalg);
82 if (pktype == KEY_UNSPEC) {
83 /* this is perfectly legal */
84 logit("userauth_hostbased: unsupported "
85 "public key algorithm: %s", pkalg);
88 key = key_from_blob(pkblob, blen);
90 error("userauth_hostbased: cannot decode key: %s", pkalg);
93 if (key->type != pktype) {
94 error("userauth_hostbased: type mismatch for decoded key "
95 "(received %d, expected %d)", key->type, pktype);
98 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
101 buffer_put_string(&b, session_id2, session_id2_len);
102 /* reconstruct packet */
103 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
104 buffer_put_cstring(&b, authctxt->user);
105 buffer_put_cstring(&b, service);
106 buffer_put_cstring(&b, "hostbased");
107 buffer_put_string(&b, pkalg, alen);
108 buffer_put_string(&b, pkblob, blen);
109 buffer_put_cstring(&b, chost);
110 buffer_put_cstring(&b, cuser);
114 /* test for allowed key and correct signature */
116 if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
117 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
118 buffer_len(&b))) == 1)
123 debug2("userauth_hostbased: authenticated %d", authenticated);
131 return authenticated;
134 /* return 1 if given hostkey is allowed */
136 hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
139 const char *resolvedname, *ipaddr, *lookup;
140 HostStatus host_status;
143 resolvedname = get_canonical_hostname(options.use_dns);
144 ipaddr = get_remote_ipaddr();
146 debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s",
147 chost, resolvedname, ipaddr);
149 if (options.hostbased_uses_name_from_packet_only) {
150 if (auth_rhosts2(pw, cuser, chost, chost) == 0)
154 if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
155 debug2("stripping trailing dot from chost %s", chost);
156 chost[len - 1] = '\0';
158 if (strcasecmp(resolvedname, chost) != 0)
159 logit("userauth_hostbased mismatch: "
160 "client sends %s, but we resolve %s to %s",
161 chost, ipaddr, resolvedname);
162 if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0)
164 lookup = resolvedname;
166 debug2("userauth_hostbased: access allowed by auth_rhosts2");
168 host_status = check_key_in_hostfiles(pw, key, lookup,
169 _PATH_SSH_SYSTEM_HOSTFILE,
170 options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
172 /* backward compat if no key has been found. */
173 if (host_status == HOST_NEW)
174 host_status = check_key_in_hostfiles(pw, key, lookup,
175 _PATH_SSH_SYSTEM_HOSTFILE2,
176 options.ignore_user_known_hosts ? NULL :
177 _PATH_SSH_USER_HOSTFILE2);
179 return (host_status == HOST_OK);
182 Authmethod method_hostbased = {
185 &options.hostbased_authentication