Annotation of src/usr.bin/ssh/auth2-hostbased.c, Revision 1.10
1.10 ! stevesk 1: /* $OpenBSD: auth2-hostbased.c,v 1.9 2006/07/06 16:03:53 stevesk Exp $ */
1.1 markus 2: /*
3: * Copyright (c) 2000 Markus Friedl. All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
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.
13: *
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.
24: */
25:
26: #include "includes.h"
1.9 stevesk 27:
28: #include <sys/types.h>
29:
30: #include <pwd.h>
1.10 ! stevesk 31: #include <string.h>
1.1 markus 32:
33: #include "ssh2.h"
34: #include "xmalloc.h"
35: #include "packet.h"
36: #include "buffer.h"
37: #include "log.h"
38: #include "servconf.h"
39: #include "compat.h"
40: #include "bufaux.h"
41: #include "auth.h"
42: #include "key.h"
43: #include "canohost.h"
44: #include "monitor_wrap.h"
45: #include "pathnames.h"
46:
47: /* import */
48: extern ServerOptions options;
49: extern u_char *session_id2;
1.5 markus 50: extern u_int session_id2_len;
1.1 markus 51:
1.2 markus 52: static int
1.1 markus 53: userauth_hostbased(Authctxt *authctxt)
54: {
55: Buffer b;
56: Key *key = NULL;
57: char *pkalg, *cuser, *chost, *service;
58: u_char *pkblob, *sig;
59: u_int alen, blen, slen;
60: int pktype;
61: int authenticated = 0;
62:
63: if (!authctxt->valid) {
64: debug2("userauth_hostbased: disabled because of invalid user");
65: return 0;
66: }
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);
72:
73: debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
74: cuser, chost, pkalg, slen);
75: #ifdef DEBUG_PK
76: debug("signature:");
77: buffer_init(&b);
78: buffer_append(&b, sig, slen);
79: buffer_dump(&b);
80: buffer_free(&b);
81: #endif
82: pktype = key_type_from_name(pkalg);
83: if (pktype == KEY_UNSPEC) {
84: /* this is perfectly legal */
1.3 itojun 85: logit("userauth_hostbased: unsupported "
1.1 markus 86: "public key algorithm: %s", pkalg);
87: goto done;
88: }
89: key = key_from_blob(pkblob, blen);
90: if (key == NULL) {
91: error("userauth_hostbased: cannot decode key: %s", pkalg);
92: goto done;
93: }
94: if (key->type != pktype) {
95: error("userauth_hostbased: type mismatch for decoded key "
96: "(received %d, expected %d)", key->type, pktype);
97: goto done;
98: }
99: service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
100: authctxt->service;
101: buffer_init(&b);
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);
112: #ifdef DEBUG_PK
113: buffer_dump(&b);
114: #endif
115: /* test for allowed key and correct signature */
116: authenticated = 0;
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)
120: authenticated = 1;
121:
1.6 markus 122: buffer_free(&b);
1.1 markus 123: done:
124: debug2("userauth_hostbased: authenticated %d", authenticated);
125: if (key != NULL)
126: key_free(key);
127: xfree(pkalg);
128: xfree(pkblob);
129: xfree(cuser);
130: xfree(chost);
131: xfree(sig);
132: return authenticated;
133: }
134:
135: /* return 1 if given hostkey is allowed */
136: int
137: hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
138: Key *key)
139: {
140: const char *resolvedname, *ipaddr, *lookup;
141: HostStatus host_status;
142: int len;
143:
1.4 markus 144: resolvedname = get_canonical_hostname(options.use_dns);
1.1 markus 145: ipaddr = get_remote_ipaddr();
146:
147: debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s",
148: chost, resolvedname, ipaddr);
149:
150: if (options.hostbased_uses_name_from_packet_only) {
151: if (auth_rhosts2(pw, cuser, chost, chost) == 0)
152: return 0;
153: lookup = chost;
154: } else {
155: if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
156: debug2("stripping trailing dot from chost %s", chost);
157: chost[len - 1] = '\0';
158: }
159: if (strcasecmp(resolvedname, chost) != 0)
1.3 itojun 160: logit("userauth_hostbased mismatch: "
1.1 markus 161: "client sends %s, but we resolve %s to %s",
162: chost, ipaddr, resolvedname);
163: if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0)
164: return 0;
165: lookup = resolvedname;
166: }
167: debug2("userauth_hostbased: access allowed by auth_rhosts2");
168:
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);
172:
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);
179:
180: return (host_status == HOST_OK);
181: }
1.2 markus 182:
183: Authmethod method_hostbased = {
184: "hostbased",
185: userauth_hostbased,
186: &options.hostbased_authentication
187: };
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