1 /* $OpenBSD: auth2-hostbased.c,v 1.12 2008/07/17 08:51:07 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
,
146 const char *resolvedname
, *ipaddr
, *lookup
;
147 HostStatus host_status
;
150 if (blacklisted_key(key
)) {
151 fp
= key_fingerprint(key
, SSH_FP_MD5
, SSH_FP_HEX
);
152 if (options
.permit_blacklisted_keys
)
153 logit("Public key %s blacklisted (see "
154 "ssh-vulnkey(1)); continuing anyway", fp
);
156 logit("Public key %s blacklisted (see "
157 "ssh-vulnkey(1))", fp
);
159 if (!options
.permit_blacklisted_keys
)
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 host_status
= check_key_in_hostfiles(pw
, key
, lookup
,
190 _PATH_SSH_SYSTEM_HOSTFILE
,
191 options
.ignore_user_known_hosts
? NULL
: _PATH_SSH_USER_HOSTFILE
);
193 /* backward compat if no key has been found. */
194 if (host_status
== HOST_NEW
)
195 host_status
= check_key_in_hostfiles(pw
, key
, lookup
,
196 _PATH_SSH_SYSTEM_HOSTFILE2
,
197 options
.ignore_user_known_hosts
? NULL
:
198 _PATH_SSH_USER_HOSTFILE2
);
200 return (host_status
== HOST_OK
);
203 Authmethod method_hostbased
= {
206 &options
.hostbased_authentication