Annotation of src/usr.bin/ssh/auth2-hostbased.c, Revision 1.16
1.16 ! djm 1: /* $OpenBSD: auth2-hostbased.c,v 1.15 2013/05/17 00:13:13 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:
1.9 stevesk 26:
27: #include <sys/types.h>
28:
29: #include <pwd.h>
1.10 stevesk 30: #include <string.h>
1.11 deraadt 31: #include <stdarg.h>
1.1 markus 32:
1.11 deraadt 33: #include "xmalloc.h"
1.1 markus 34: #include "ssh2.h"
35: #include "packet.h"
36: #include "buffer.h"
37: #include "log.h"
38: #include "servconf.h"
39: #include "compat.h"
1.11 deraadt 40: #include "key.h"
41: #include "hostfile.h"
1.1 markus 42: #include "auth.h"
43: #include "canohost.h"
1.11 deraadt 44: #ifdef GSSAPI
45: #include "ssh-gss.h"
46: #endif
1.1 markus 47: #include "monitor_wrap.h"
48: #include "pathnames.h"
49:
50: /* import */
51: extern ServerOptions options;
52: extern u_char *session_id2;
1.5 markus 53: extern u_int session_id2_len;
1.1 markus 54:
1.2 markus 55: static int
1.1 markus 56: userauth_hostbased(Authctxt *authctxt)
57: {
58: Buffer b;
59: Key *key = NULL;
60: char *pkalg, *cuser, *chost, *service;
61: u_char *pkblob, *sig;
62: u_int alen, blen, slen;
63: int pktype;
64: int authenticated = 0;
65:
66: if (!authctxt->valid) {
67: debug2("userauth_hostbased: disabled because of invalid user");
68: return 0;
69: }
70: pkalg = packet_get_string(&alen);
71: pkblob = packet_get_string(&blen);
72: chost = packet_get_string(NULL);
73: cuser = packet_get_string(NULL);
74: sig = packet_get_string(&slen);
75:
76: debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
77: cuser, chost, pkalg, slen);
78: #ifdef DEBUG_PK
79: debug("signature:");
80: buffer_init(&b);
81: buffer_append(&b, sig, slen);
82: buffer_dump(&b);
83: buffer_free(&b);
84: #endif
85: pktype = key_type_from_name(pkalg);
86: if (pktype == KEY_UNSPEC) {
87: /* this is perfectly legal */
1.3 itojun 88: logit("userauth_hostbased: unsupported "
1.1 markus 89: "public key algorithm: %s", pkalg);
90: goto done;
91: }
92: key = key_from_blob(pkblob, blen);
93: if (key == NULL) {
94: error("userauth_hostbased: cannot decode key: %s", pkalg);
95: goto done;
96: }
97: if (key->type != pktype) {
98: error("userauth_hostbased: type mismatch for decoded key "
99: "(received %d, expected %d)", key->type, pktype);
100: goto done;
101: }
102: service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
103: authctxt->service;
104: buffer_init(&b);
105: buffer_put_string(&b, session_id2, session_id2_len);
106: /* reconstruct packet */
107: buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
108: buffer_put_cstring(&b, authctxt->user);
109: buffer_put_cstring(&b, service);
110: buffer_put_cstring(&b, "hostbased");
111: buffer_put_string(&b, pkalg, alen);
112: buffer_put_string(&b, pkblob, blen);
113: buffer_put_cstring(&b, chost);
114: buffer_put_cstring(&b, cuser);
115: #ifdef DEBUG_PK
116: buffer_dump(&b);
117: #endif
1.16 ! djm 118:
! 119: pubkey_auth_info(authctxt, key,
! 120: "client user \"%.100s\", client host \"%.100s\"", cuser, chost);
! 121:
1.1 markus 122: /* test for allowed key and correct signature */
123: authenticated = 0;
124: if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
125: PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
126: buffer_len(&b))) == 1)
127: authenticated = 1;
128:
1.6 markus 129: buffer_free(&b);
1.1 markus 130: done:
131: debug2("userauth_hostbased: authenticated %d", authenticated);
132: if (key != NULL)
133: key_free(key);
1.15 djm 134: free(pkalg);
135: free(pkblob);
136: free(cuser);
137: free(chost);
138: free(sig);
1.1 markus 139: return authenticated;
140: }
141:
142: /* return 1 if given hostkey is allowed */
143: int
144: hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
145: Key *key)
146: {
1.14 djm 147: const char *resolvedname, *ipaddr, *lookup, *reason;
1.1 markus 148: HostStatus host_status;
149: int len;
1.14 djm 150: char *fp;
1.13 djm 151:
152: if (auth_key_is_revoked(key))
153: return 0;
1.1 markus 154:
1.4 markus 155: resolvedname = get_canonical_hostname(options.use_dns);
1.1 markus 156: ipaddr = get_remote_ipaddr();
157:
158: debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s",
159: chost, resolvedname, ipaddr);
160:
1.12 djm 161: if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
162: debug2("stripping trailing dot from chost %s", chost);
163: chost[len - 1] = '\0';
164: }
165:
1.1 markus 166: if (options.hostbased_uses_name_from_packet_only) {
167: if (auth_rhosts2(pw, cuser, chost, chost) == 0)
168: return 0;
169: lookup = chost;
170: } else {
171: if (strcasecmp(resolvedname, chost) != 0)
1.3 itojun 172: logit("userauth_hostbased mismatch: "
1.1 markus 173: "client sends %s, but we resolve %s to %s",
174: chost, ipaddr, resolvedname);
175: if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0)
176: return 0;
177: lookup = resolvedname;
178: }
179: debug2("userauth_hostbased: access allowed by auth_rhosts2");
180:
1.14 djm 181: if (key_is_cert(key) &&
182: key_cert_check_authority(key, 1, 0, lookup, &reason)) {
183: error("%s", reason);
184: auth_debug_add("%s", reason);
185: return 0;
186: }
187:
1.1 markus 188: host_status = check_key_in_hostfiles(pw, key, lookup,
189: _PATH_SSH_SYSTEM_HOSTFILE,
190: options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
191:
192: /* backward compat if no key has been found. */
1.14 djm 193: if (host_status == HOST_NEW) {
1.1 markus 194: host_status = check_key_in_hostfiles(pw, key, lookup,
195: _PATH_SSH_SYSTEM_HOSTFILE2,
196: options.ignore_user_known_hosts ? NULL :
197: _PATH_SSH_USER_HOSTFILE2);
1.14 djm 198: }
199:
200: if (host_status == HOST_OK) {
201: if (key_is_cert(key)) {
202: fp = key_fingerprint(key->cert->signature_key,
203: SSH_FP_MD5, SSH_FP_HEX);
204: verbose("Accepted certificate ID \"%s\" signed by "
205: "%s CA %s from %s@%s", key->cert->key_id,
206: key_type(key->cert->signature_key), fp,
207: cuser, lookup);
208: } else {
209: fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
210: verbose("Accepted %s public key %s from %s@%s",
211: key_type(key), fp, cuser, lookup);
212: }
1.15 djm 213: free(fp);
1.14 djm 214: }
1.1 markus 215:
216: return (host_status == HOST_OK);
217: }
1.2 markus 218:
219: Authmethod method_hostbased = {
220: "hostbased",
221: userauth_hostbased,
222: &options.hostbased_authentication
223: };
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