Annotation of src/usr.bin/ssh/auth2-hostbased.c, Revision 1.22
1.22 ! djm 1: /* $OpenBSD: auth2-hostbased.c,v 1.21 2015/01/08 10:14:08 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"
1.18 millert 38: #include "misc.h"
1.1 markus 39: #include "servconf.h"
40: #include "compat.h"
1.11 deraadt 41: #include "key.h"
42: #include "hostfile.h"
1.1 markus 43: #include "auth.h"
44: #include "canohost.h"
1.11 deraadt 45: #ifdef GSSAPI
46: #include "ssh-gss.h"
47: #endif
1.1 markus 48: #include "monitor_wrap.h"
49: #include "pathnames.h"
1.22 ! djm 50: #include "match.h"
1.1 markus 51:
52: /* import */
53: extern ServerOptions options;
54: extern u_char *session_id2;
1.5 markus 55: extern u_int session_id2_len;
1.1 markus 56:
1.2 markus 57: static int
1.1 markus 58: userauth_hostbased(Authctxt *authctxt)
59: {
60: Buffer b;
61: Key *key = NULL;
62: char *pkalg, *cuser, *chost, *service;
63: u_char *pkblob, *sig;
64: u_int alen, blen, slen;
65: int pktype;
66: int authenticated = 0;
67:
68: if (!authctxt->valid) {
69: debug2("userauth_hostbased: disabled because of invalid user");
70: return 0;
71: }
72: pkalg = packet_get_string(&alen);
73: pkblob = packet_get_string(&blen);
74: chost = packet_get_string(NULL);
75: cuser = packet_get_string(NULL);
76: sig = packet_get_string(&slen);
77:
78: debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
79: cuser, chost, pkalg, slen);
80: #ifdef DEBUG_PK
81: debug("signature:");
82: buffer_init(&b);
83: buffer_append(&b, sig, slen);
84: buffer_dump(&b);
85: buffer_free(&b);
86: #endif
1.21 djm 87: /* XXX provide some way to allow admin to specify key types accepted */
1.1 markus 88: pktype = key_type_from_name(pkalg);
89: if (pktype == KEY_UNSPEC) {
90: /* this is perfectly legal */
1.3 itojun 91: logit("userauth_hostbased: unsupported "
1.1 markus 92: "public key algorithm: %s", pkalg);
93: goto done;
94: }
95: key = key_from_blob(pkblob, blen);
96: if (key == NULL) {
97: error("userauth_hostbased: cannot decode key: %s", pkalg);
98: goto done;
99: }
100: if (key->type != pktype) {
101: error("userauth_hostbased: type mismatch for decoded key "
102: "(received %d, expected %d)", key->type, pktype);
1.17 djm 103: goto done;
104: }
105: if (key_type_plain(key->type) == KEY_RSA &&
106: (datafellows & SSH_BUG_RSASIGMD5) != 0) {
107: error("Refusing RSA key because peer uses unsafe "
108: "signature format");
1.1 markus 109: goto done;
110: }
1.22 ! djm 111: if (match_pattern_list(sshkey_ssh_name(key),
! 112: options.hostbased_key_types,
! 113: strlen(options.hostbased_key_types), 0) != 1) {
! 114: logit("%s: key type %s not in HostbasedAcceptedKeyTypes",
! 115: __func__, sshkey_type(key));
! 116: goto done;
! 117: }
! 118:
1.1 markus 119: service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
120: authctxt->service;
121: buffer_init(&b);
122: buffer_put_string(&b, session_id2, session_id2_len);
123: /* reconstruct packet */
124: buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
125: buffer_put_cstring(&b, authctxt->user);
126: buffer_put_cstring(&b, service);
127: buffer_put_cstring(&b, "hostbased");
128: buffer_put_string(&b, pkalg, alen);
129: buffer_put_string(&b, pkblob, blen);
130: buffer_put_cstring(&b, chost);
131: buffer_put_cstring(&b, cuser);
132: #ifdef DEBUG_PK
133: buffer_dump(&b);
134: #endif
1.16 djm 135:
136: pubkey_auth_info(authctxt, key,
137: "client user \"%.100s\", client host \"%.100s\"", cuser, chost);
138:
1.1 markus 139: /* test for allowed key and correct signature */
140: authenticated = 0;
141: if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
142: PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
143: buffer_len(&b))) == 1)
144: authenticated = 1;
145:
1.6 markus 146: buffer_free(&b);
1.1 markus 147: done:
148: debug2("userauth_hostbased: authenticated %d", authenticated);
149: if (key != NULL)
150: key_free(key);
1.15 djm 151: free(pkalg);
152: free(pkblob);
153: free(cuser);
154: free(chost);
155: free(sig);
1.1 markus 156: return authenticated;
157: }
158:
159: /* return 1 if given hostkey is allowed */
160: int
161: hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
162: Key *key)
163: {
1.14 djm 164: const char *resolvedname, *ipaddr, *lookup, *reason;
1.1 markus 165: HostStatus host_status;
166: int len;
1.14 djm 167: char *fp;
1.13 djm 168:
169: if (auth_key_is_revoked(key))
170: return 0;
1.1 markus 171:
1.4 markus 172: resolvedname = get_canonical_hostname(options.use_dns);
1.1 markus 173: ipaddr = get_remote_ipaddr();
174:
1.20 djm 175: debug2("%s: chost %s resolvedname %s ipaddr %s", __func__,
1.1 markus 176: chost, resolvedname, ipaddr);
177:
1.12 djm 178: if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
179: debug2("stripping trailing dot from chost %s", chost);
180: chost[len - 1] = '\0';
181: }
182:
1.1 markus 183: if (options.hostbased_uses_name_from_packet_only) {
1.20 djm 184: if (auth_rhosts2(pw, cuser, chost, chost) == 0) {
185: debug2("%s: auth_rhosts2 refused "
186: "user \"%.100s\" host \"%.100s\" (from packet)",
187: __func__, cuser, chost);
1.1 markus 188: return 0;
1.20 djm 189: }
1.1 markus 190: lookup = chost;
191: } else {
192: if (strcasecmp(resolvedname, chost) != 0)
1.3 itojun 193: logit("userauth_hostbased mismatch: "
1.1 markus 194: "client sends %s, but we resolve %s to %s",
195: chost, ipaddr, resolvedname);
1.20 djm 196: if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0) {
197: debug2("%s: auth_rhosts2 refused "
198: "user \"%.100s\" host \"%.100s\" addr \"%.100s\"",
199: __func__, cuser, resolvedname, ipaddr);
1.1 markus 200: return 0;
1.20 djm 201: }
1.1 markus 202: lookup = resolvedname;
203: }
1.20 djm 204: debug2("%s: access allowed by auth_rhosts2", __func__);
1.1 markus 205:
1.14 djm 206: if (key_is_cert(key) &&
207: key_cert_check_authority(key, 1, 0, lookup, &reason)) {
208: error("%s", reason);
209: auth_debug_add("%s", reason);
210: return 0;
211: }
212:
1.1 markus 213: host_status = check_key_in_hostfiles(pw, key, lookup,
214: _PATH_SSH_SYSTEM_HOSTFILE,
215: options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
216:
217: /* backward compat if no key has been found. */
1.14 djm 218: if (host_status == HOST_NEW) {
1.1 markus 219: host_status = check_key_in_hostfiles(pw, key, lookup,
220: _PATH_SSH_SYSTEM_HOSTFILE2,
221: options.ignore_user_known_hosts ? NULL :
222: _PATH_SSH_USER_HOSTFILE2);
1.14 djm 223: }
224:
225: if (host_status == HOST_OK) {
226: if (key_is_cert(key)) {
227: fp = key_fingerprint(key->cert->signature_key,
1.19 djm 228: options.fingerprint_hash, SSH_FP_DEFAULT);
1.14 djm 229: verbose("Accepted certificate ID \"%s\" signed by "
230: "%s CA %s from %s@%s", key->cert->key_id,
231: key_type(key->cert->signature_key), fp,
232: cuser, lookup);
233: } else {
1.19 djm 234: fp = key_fingerprint(key, options.fingerprint_hash,
235: SSH_FP_DEFAULT);
1.14 djm 236: verbose("Accepted %s public key %s from %s@%s",
237: key_type(key), fp, cuser, lookup);
238: }
1.15 djm 239: free(fp);
1.14 djm 240: }
1.1 markus 241:
242: return (host_status == HOST_OK);
243: }
1.2 markus 244:
245: Authmethod method_hostbased = {
246: "hostbased",
247: userauth_hostbased,
248: &options.hostbased_authentication
249: };
![[BACK]](/icons/back.gif){kind=icon}
Return to auth2-hostbased.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh