1 /* $OpenBSD: auth2-hostbased.c,v 1.10 2006/07/22 20:48:22 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>
44 #include "monitor_wrap.h"
45 #include "pathnames.h"
48 extern ServerOptions options;
49 extern u_char *session_id2;
50 extern u_int session_id2_len;
53 userauth_hostbased(Authctxt *authctxt)
57 char *pkalg, *cuser, *chost, *service;
59 u_int alen, blen, slen;
61 int authenticated = 0;
63 if (!authctxt->valid) {
64 debug2("userauth_hostbased: disabled because of invalid user");
67 pkalg = packet_get_string(&alen);
68 pkblob = packet_get_string(&blen);
69 chost = packet_get_string(NULL);
70 cuser = packet_get_string(NULL);
71 sig = packet_get_string(&slen);
73 debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
74 cuser, chost, pkalg, slen);
78 buffer_append(&b, sig, slen);
82 pktype = key_type_from_name(pkalg);
83 if (pktype == KEY_UNSPEC) {
84 /* this is perfectly legal */
85 logit("userauth_hostbased: unsupported "
86 "public key algorithm: %s", pkalg);
89 key = key_from_blob(pkblob, blen);
91 error("userauth_hostbased: cannot decode key: %s", pkalg);
94 if (key->type != pktype) {
95 error("userauth_hostbased: type mismatch for decoded key "
96 "(received %d, expected %d)", key->type, pktype);
99 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
102 buffer_put_string(&b, session_id2, session_id2_len);
103 /* reconstruct packet */
104 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
105 buffer_put_cstring(&b, authctxt->user);
106 buffer_put_cstring(&b, service);
107 buffer_put_cstring(&b, "hostbased");
108 buffer_put_string(&b, pkalg, alen);
109 buffer_put_string(&b, pkblob, blen);
110 buffer_put_cstring(&b, chost);
111 buffer_put_cstring(&b, cuser);
115 /* test for allowed key and correct signature */
117 if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
118 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
119 buffer_len(&b))) == 1)
124 debug2("userauth_hostbased: authenticated %d", authenticated);
132 return authenticated;
135 /* return 1 if given hostkey is allowed */
137 hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
140 const char *resolvedname, *ipaddr, *lookup;
141 HostStatus host_status;
144 resolvedname = get_canonical_hostname(options.use_dns);
145 ipaddr = get_remote_ipaddr();
147 debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s",
148 chost, resolvedname, ipaddr);
150 if (options.hostbased_uses_name_from_packet_only) {
151 if (auth_rhosts2(pw, cuser, chost, chost) == 0)
155 if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
156 debug2("stripping trailing dot from chost %s", chost);
157 chost[len - 1] = '\0';
159 if (strcasecmp(resolvedname, chost) != 0)
160 logit("userauth_hostbased mismatch: "
161 "client sends %s, but we resolve %s to %s",
162 chost, ipaddr, resolvedname);
163 if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0)
165 lookup = resolvedname;
167 debug2("userauth_hostbased: access allowed by auth_rhosts2");
169 host_status = check_key_in_hostfiles(pw, key, lookup,
170 _PATH_SSH_SYSTEM_HOSTFILE,
171 options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
173 /* backward compat if no key has been found. */
174 if (host_status == HOST_NEW)
175 host_status = check_key_in_hostfiles(pw, key, lookup,
176 _PATH_SSH_SYSTEM_HOSTFILE2,
177 options.ignore_user_known_hosts ? NULL :
178 _PATH_SSH_USER_HOSTFILE2);
180 return (host_status == HOST_OK);
183 Authmethod method_hostbased = {
186 &options.hostbased_authentication