Annotation of src/usr.bin/ssh/auth2-hostbased.c, Revision 1.3
1.1 markus 1: /*
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"
1.3 ! itojun 26: RCSID("$OpenBSD: auth2-hostbased.c,v 1.2 2002/05/31 11:35:15 markus Exp $");
1.1 markus 27:
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 */
43: extern ServerOptions options;
44: extern u_char *session_id2;
45: extern int session_id2_len;
46:
1.2 markus 47: static int
1.1 markus 48: userauth_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 */
1.3 ! itojun 80: logit("userauth_hostbased: unsupported "
1.1 markus 81: "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);
118: done:
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 */
131: int
132: hostbased_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:
139: resolvedname = get_canonical_hostname(options.verify_reverse_mapping);
140: 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)
1.3 ! itojun 155: logit("userauth_hostbased mismatch: "
1.1 markus 156: "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: }
1.2 markus 177:
178: Authmethod method_hostbased = {
179: "hostbased",
180: userauth_hostbased,
181: &options.hostbased_authentication
182: };
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