Annotation of src/usr.bin/ssh/auth2-hostbased.c, Revision 1.27
1.27 ! markus 1: /* $OpenBSD: auth2-hostbased.c,v 1.26 2016/03/07 19:02:43 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;
1.27 ! markus 61: struct sshkey *key = NULL;
1.1 markus 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
87: pktype = key_type_from_name(pkalg);
88: if (pktype == KEY_UNSPEC) {
89: /* this is perfectly legal */
1.3 itojun 90: logit("userauth_hostbased: unsupported "
1.1 markus 91: "public key algorithm: %s", pkalg);
92: goto done;
93: }
94: key = key_from_blob(pkblob, blen);
95: if (key == NULL) {
96: error("userauth_hostbased: cannot decode key: %s", pkalg);
97: goto done;
98: }
99: if (key->type != pktype) {
100: error("userauth_hostbased: type mismatch for decoded key "
101: "(received %d, expected %d)", key->type, pktype);
1.17 djm 102: goto done;
103: }
104: if (key_type_plain(key->type) == KEY_RSA &&
105: (datafellows & SSH_BUG_RSASIGMD5) != 0) {
106: error("Refusing RSA key because peer uses unsafe "
107: "signature format");
1.1 markus 108: goto done;
109: }
1.22 djm 110: if (match_pattern_list(sshkey_ssh_name(key),
1.25 djm 111: options.hostbased_key_types, 0) != 1) {
1.22 djm 112: logit("%s: key type %s not in HostbasedAcceptedKeyTypes",
113: __func__, sshkey_type(key));
114: goto done;
115: }
116:
1.1 markus 117: service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
118: authctxt->service;
119: buffer_init(&b);
120: buffer_put_string(&b, session_id2, session_id2_len);
121: /* reconstruct packet */
122: buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
123: buffer_put_cstring(&b, authctxt->user);
124: buffer_put_cstring(&b, service);
125: buffer_put_cstring(&b, "hostbased");
126: buffer_put_string(&b, pkalg, alen);
127: buffer_put_string(&b, pkblob, blen);
128: buffer_put_cstring(&b, chost);
129: buffer_put_cstring(&b, cuser);
130: #ifdef DEBUG_PK
131: buffer_dump(&b);
132: #endif
1.16 djm 133:
134: pubkey_auth_info(authctxt, key,
135: "client user \"%.100s\", client host \"%.100s\"", cuser, chost);
136:
1.1 markus 137: /* test for allowed key and correct signature */
138: authenticated = 0;
139: if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
140: PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
141: buffer_len(&b))) == 1)
142: authenticated = 1;
143:
1.6 markus 144: buffer_free(&b);
1.1 markus 145: done:
146: debug2("userauth_hostbased: authenticated %d", authenticated);
147: if (key != NULL)
148: key_free(key);
1.15 djm 149: free(pkalg);
150: free(pkblob);
151: free(cuser);
152: free(chost);
153: free(sig);
1.1 markus 154: return authenticated;
155: }
156:
157: /* return 1 if given hostkey is allowed */
158: int
159: hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
1.27 ! markus 160: struct sshkey *key)
1.1 markus 161: {
1.26 djm 162: struct ssh *ssh = active_state; /* XXX */
1.14 djm 163: const char *resolvedname, *ipaddr, *lookup, *reason;
1.1 markus 164: HostStatus host_status;
165: int len;
1.14 djm 166: char *fp;
1.13 djm 167:
168: if (auth_key_is_revoked(key))
169: return 0;
1.1 markus 170:
1.26 djm 171: resolvedname = auth_get_canonical_hostname(ssh, options.use_dns);
172: ipaddr = ssh_remote_ipaddr(ssh);
1.1 markus 173:
1.20 djm 174: debug2("%s: chost %s resolvedname %s ipaddr %s", __func__,
1.1 markus 175: chost, resolvedname, ipaddr);
176:
1.12 djm 177: if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
178: debug2("stripping trailing dot from chost %s", chost);
179: chost[len - 1] = '\0';
180: }
181:
1.1 markus 182: if (options.hostbased_uses_name_from_packet_only) {
1.20 djm 183: if (auth_rhosts2(pw, cuser, chost, chost) == 0) {
184: debug2("%s: auth_rhosts2 refused "
185: "user \"%.100s\" host \"%.100s\" (from packet)",
186: __func__, cuser, chost);
1.1 markus 187: return 0;
1.20 djm 188: }
1.1 markus 189: lookup = chost;
190: } else {
191: if (strcasecmp(resolvedname, chost) != 0)
1.3 itojun 192: logit("userauth_hostbased mismatch: "
1.1 markus 193: "client sends %s, but we resolve %s to %s",
194: chost, ipaddr, resolvedname);
1.20 djm 195: if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0) {
196: debug2("%s: auth_rhosts2 refused "
197: "user \"%.100s\" host \"%.100s\" addr \"%.100s\"",
198: __func__, cuser, resolvedname, ipaddr);
1.1 markus 199: return 0;
1.20 djm 200: }
1.1 markus 201: lookup = resolvedname;
202: }
1.20 djm 203: debug2("%s: access allowed by auth_rhosts2", __func__);
1.1 markus 204:
1.14 djm 205: if (key_is_cert(key) &&
206: key_cert_check_authority(key, 1, 0, lookup, &reason)) {
207: error("%s", reason);
208: auth_debug_add("%s", reason);
209: return 0;
210: }
211:
1.1 markus 212: host_status = check_key_in_hostfiles(pw, key, lookup,
213: _PATH_SSH_SYSTEM_HOSTFILE,
214: options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
215:
216: /* backward compat if no key has been found. */
1.14 djm 217: if (host_status == HOST_NEW) {
1.1 markus 218: host_status = check_key_in_hostfiles(pw, key, lookup,
219: _PATH_SSH_SYSTEM_HOSTFILE2,
220: options.ignore_user_known_hosts ? NULL :
221: _PATH_SSH_USER_HOSTFILE2);
1.14 djm 222: }
223:
224: if (host_status == HOST_OK) {
225: if (key_is_cert(key)) {
1.24 djm 226: if ((fp = sshkey_fingerprint(key->cert->signature_key,
227: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
228: fatal("%s: sshkey_fingerprint fail", __func__);
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 {
1.24 djm 234: if ((fp = sshkey_fingerprint(key,
235: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
236: fatal("%s: sshkey_fingerprint fail", __func__);
1.14 djm 237: verbose("Accepted %s public key %s from %s@%s",
238: key_type(key), fp, cuser, lookup);
239: }
1.15 djm 240: free(fp);
1.14 djm 241: }
1.1 markus 242:
243: return (host_status == HOST_OK);
244: }
1.2 markus 245:
246: Authmethod method_hostbased = {
247: "hostbased",
248: userauth_hostbased,
249: &options.hostbased_authentication
250: };
![[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