Annotation of src/usr.bin/ssh/auth2-hostbased.c, Revision 1.9
1.9 ! stevesk 1: /* $OpenBSD: auth2-hostbased.c,v 1.8 2006/03/25 13:17:01 djm 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>
1.1 markus 31:
32: #include "ssh2.h"
33: #include "xmalloc.h"
34: #include "packet.h"
35: #include "buffer.h"
36: #include "log.h"
37: #include "servconf.h"
38: #include "compat.h"
39: #include "bufaux.h"
40: #include "auth.h"
41: #include "key.h"
42: #include "canohost.h"
43: #include "monitor_wrap.h"
44: #include "pathnames.h"
45:
46: /* import */
47: extern ServerOptions options;
48: extern u_char *session_id2;
1.5 markus 49: extern u_int session_id2_len;
1.1 markus 50:
1.2 markus 51: static int
1.1 markus 52: userauth_hostbased(Authctxt *authctxt)
53: {
54: Buffer b;
55: Key *key = NULL;
56: char *pkalg, *cuser, *chost, *service;
57: u_char *pkblob, *sig;
58: u_int alen, blen, slen;
59: int pktype;
60: int authenticated = 0;
61:
62: if (!authctxt->valid) {
63: debug2("userauth_hostbased: disabled because of invalid user");
64: return 0;
65: }
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);
71:
72: debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
73: cuser, chost, pkalg, slen);
74: #ifdef DEBUG_PK
75: debug("signature:");
76: buffer_init(&b);
77: buffer_append(&b, sig, slen);
78: buffer_dump(&b);
79: buffer_free(&b);
80: #endif
81: pktype = key_type_from_name(pkalg);
82: if (pktype == KEY_UNSPEC) {
83: /* this is perfectly legal */
1.3 itojun 84: logit("userauth_hostbased: unsupported "
1.1 markus 85: "public key algorithm: %s", pkalg);
86: goto done;
87: }
88: key = key_from_blob(pkblob, blen);
89: if (key == NULL) {
90: error("userauth_hostbased: cannot decode key: %s", pkalg);
91: goto done;
92: }
93: if (key->type != pktype) {
94: error("userauth_hostbased: type mismatch for decoded key "
95: "(received %d, expected %d)", key->type, pktype);
96: goto done;
97: }
98: service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
99: authctxt->service;
100: buffer_init(&b);
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);
111: #ifdef DEBUG_PK
112: buffer_dump(&b);
113: #endif
114: /* test for allowed key and correct signature */
115: authenticated = 0;
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)
119: authenticated = 1;
120:
1.6 markus 121: buffer_free(&b);
1.1 markus 122: done:
123: debug2("userauth_hostbased: authenticated %d", authenticated);
124: if (key != NULL)
125: key_free(key);
126: xfree(pkalg);
127: xfree(pkblob);
128: xfree(cuser);
129: xfree(chost);
130: xfree(sig);
131: return authenticated;
132: }
133:
134: /* return 1 if given hostkey is allowed */
135: int
136: hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
137: Key *key)
138: {
139: const char *resolvedname, *ipaddr, *lookup;
140: HostStatus host_status;
141: int len;
142:
1.4 markus 143: resolvedname = get_canonical_hostname(options.use_dns);
1.1 markus 144: ipaddr = get_remote_ipaddr();
145:
146: debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s",
147: chost, resolvedname, ipaddr);
148:
149: if (options.hostbased_uses_name_from_packet_only) {
150: if (auth_rhosts2(pw, cuser, chost, chost) == 0)
151: return 0;
152: lookup = chost;
153: } else {
154: if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
155: debug2("stripping trailing dot from chost %s", chost);
156: chost[len - 1] = '\0';
157: }
158: if (strcasecmp(resolvedname, chost) != 0)
1.3 itojun 159: logit("userauth_hostbased mismatch: "
1.1 markus 160: "client sends %s, but we resolve %s to %s",
161: chost, ipaddr, resolvedname);
162: if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0)
163: return 0;
164: lookup = resolvedname;
165: }
166: debug2("userauth_hostbased: access allowed by auth_rhosts2");
167:
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);
171:
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);
178:
179: return (host_status == HOST_OK);
180: }
1.2 markus 181:
182: Authmethod method_hostbased = {
183: "hostbased",
184: userauth_hostbased,
185: &options.hostbased_authentication
186: };
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