blob: 505d3eff458758323cb9688f12692857c587b7f1 [file] [log] [blame]
Ben Lindstrom855bf3a2002-06-06 20:27:55 +00001/*
2 * Copyright (c) 2000 Markus Friedl. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 */
24
25#include "includes.h"
Darren Tucker502d3842003-06-28 12:38:01 +100026RCSID("$OpenBSD: auth2-hostbased.c,v 1.5 2003/06/24 08:23:46 markus Exp $");
Ben Lindstrom855bf3a2002-06-06 20:27:55 +000027
28#include "ssh2.h"
29#include "xmalloc.h"
30#include "packet.h"
31#include "buffer.h"
32#include "log.h"
33#include "servconf.h"
34#include "compat.h"
35#include "bufaux.h"
36#include "auth.h"
37#include "key.h"
38#include "canohost.h"
39#include "monitor_wrap.h"
40#include "pathnames.h"
41
42/* import */
43extern ServerOptions options;
44extern u_char *session_id2;
Darren Tucker502d3842003-06-28 12:38:01 +100045extern u_int session_id2_len;
Ben Lindstrom855bf3a2002-06-06 20:27:55 +000046
47static int
48userauth_hostbased(Authctxt *authctxt)
49{
50 Buffer b;
51 Key *key = NULL;
52 char *pkalg, *cuser, *chost, *service;
53 u_char *pkblob, *sig;
54 u_int alen, blen, slen;
55 int pktype;
56 int authenticated = 0;
57
58 if (!authctxt->valid) {
59 debug2("userauth_hostbased: disabled because of invalid user");
60 return 0;
61 }
62 pkalg = packet_get_string(&alen);
63 pkblob = packet_get_string(&blen);
64 chost = packet_get_string(NULL);
65 cuser = packet_get_string(NULL);
66 sig = packet_get_string(&slen);
67
68 debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
69 cuser, chost, pkalg, slen);
70#ifdef DEBUG_PK
71 debug("signature:");
72 buffer_init(&b);
73 buffer_append(&b, sig, slen);
74 buffer_dump(&b);
75 buffer_free(&b);
76#endif
77 pktype = key_type_from_name(pkalg);
78 if (pktype == KEY_UNSPEC) {
79 /* this is perfectly legal */
Damien Miller996acd22003-04-09 20:59:48 +100080 logit("userauth_hostbased: unsupported "
Ben Lindstrom855bf3a2002-06-06 20:27:55 +000081 "public key algorithm: %s", pkalg);
82 goto done;
83 }
84 key = key_from_blob(pkblob, blen);
85 if (key == NULL) {
86 error("userauth_hostbased: cannot decode key: %s", pkalg);
87 goto done;
88 }
89 if (key->type != pktype) {
90 error("userauth_hostbased: type mismatch for decoded key "
91 "(received %d, expected %d)", key->type, pktype);
92 goto done;
93 }
94 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
95 authctxt->service;
96 buffer_init(&b);
97 buffer_put_string(&b, session_id2, session_id2_len);
98 /* reconstruct packet */
99 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
100 buffer_put_cstring(&b, authctxt->user);
101 buffer_put_cstring(&b, service);
102 buffer_put_cstring(&b, "hostbased");
103 buffer_put_string(&b, pkalg, alen);
104 buffer_put_string(&b, pkblob, blen);
105 buffer_put_cstring(&b, chost);
106 buffer_put_cstring(&b, cuser);
107#ifdef DEBUG_PK
108 buffer_dump(&b);
109#endif
110 /* test for allowed key and correct signature */
111 authenticated = 0;
112 if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
113 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
114 buffer_len(&b))) == 1)
115 authenticated = 1;
116
117 buffer_clear(&b);
118done:
119 debug2("userauth_hostbased: authenticated %d", authenticated);
120 if (key != NULL)
121 key_free(key);
122 xfree(pkalg);
123 xfree(pkblob);
124 xfree(cuser);
125 xfree(chost);
126 xfree(sig);
127 return authenticated;
128}
129
130/* return 1 if given hostkey is allowed */
131int
132hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
133 Key *key)
134{
135 const char *resolvedname, *ipaddr, *lookup;
136 HostStatus host_status;
137 int len;
138
Damien Miller3a961dc2003-06-03 10:25:48 +1000139 resolvedname = get_canonical_hostname(options.use_dns);
Ben Lindstrom855bf3a2002-06-06 20:27:55 +0000140 ipaddr = get_remote_ipaddr();
141
142 debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s",
143 chost, resolvedname, ipaddr);
144
145 if (options.hostbased_uses_name_from_packet_only) {
146 if (auth_rhosts2(pw, cuser, chost, chost) == 0)
147 return 0;
148 lookup = chost;
149 } else {
150 if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
151 debug2("stripping trailing dot from chost %s", chost);
152 chost[len - 1] = '\0';
153 }
154 if (strcasecmp(resolvedname, chost) != 0)
Damien Miller996acd22003-04-09 20:59:48 +1000155 logit("userauth_hostbased mismatch: "
Ben Lindstrom855bf3a2002-06-06 20:27:55 +0000156 "client sends %s, but we resolve %s to %s",
157 chost, ipaddr, resolvedname);
158 if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0)
159 return 0;
160 lookup = resolvedname;
161 }
162 debug2("userauth_hostbased: access allowed by auth_rhosts2");
163
164 host_status = check_key_in_hostfiles(pw, key, lookup,
165 _PATH_SSH_SYSTEM_HOSTFILE,
166 options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
167
168 /* backward compat if no key has been found. */
169 if (host_status == HOST_NEW)
170 host_status = check_key_in_hostfiles(pw, key, lookup,
171 _PATH_SSH_SYSTEM_HOSTFILE2,
172 options.ignore_user_known_hosts ? NULL :
173 _PATH_SSH_USER_HOSTFILE2);
174
175 return (host_status == HOST_OK);
176}
177
178Authmethod method_hostbased = {
179 "hostbased",
180 userauth_hostbased,
181 &options.hostbased_authentication
182};