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auth2-hostbased.c

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1/* $OpenBSD: auth2-hostbased.c,v 1.38 2018/09/20 03:28:06 djm Exp $ */-
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"-
27-
28#include <sys/types.h>-
29-
30#include <pwd.h>-
31#include <string.h>-
32#include <stdarg.h>-
33-
34#include "xmalloc.h"-
35#include "ssh2.h"-
36#include "packet.h"-
37#include "sshbuf.h"-
38#include "log.h"-
39#include "misc.h"-
40#include "servconf.h"-
41#include "compat.h"-
42#include "sshkey.h"-
43#include "hostfile.h"-
44#include "auth.h"-
45#include "canohost.h"-
46#ifdef GSSAPI-
47#include "ssh-gss.h"-
48#endif-
49#include "monitor_wrap.h"-
50#include "pathnames.h"-
51#include "ssherr.h"-
52#include "match.h"-
53-
54/* import */-
55extern ServerOptions options;-
56extern u_char *session_id2;-
57extern u_int session_id2_len;-
58-
59static int-
60userauth_hostbased(struct ssh *ssh)-
61{-
62 Authctxt *authctxt = ssh->authctxt;-
63 struct sshbuf *b;-
64 struct sshkey *key = NULL;-
65 char *pkalg, *cuser, *chost;-
66 u_char *pkblob, *sig;-
67 size_t alen, blen, slen;-
68 int r, pktype, authenticated = 0;-
69-
70 /* XXX use sshkey_froms() */-
71 if ((r = sshpkt_get_cstring(ssh, &pkalg, &alen)) != 0 ||
(r = sshpkt_ge..., &alen)) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
72 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 ||
(r = sshpkt_ge..., &blen)) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
73 (r = sshpkt_get_cstring(ssh, &chost, NULL)) != 0 ||
(r = sshpkt_ge...d *)0) )) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
74 (r = sshpkt_get_cstring(ssh, &cuser, NULL)) != 0 ||
(r = sshpkt_ge...d *)0) )) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
75 (r = sshpkt_get_string(ssh, &sig, &slen)) != 0)
(r = sshpkt_ge..., &slen)) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
76 fatal("%s: packet parsing: %s", __func__, ssh_err(r));
never executed: fatal("%s: packet parsing: %s", __func__, ssh_err(r));
0
77-
78 debug("%s: cuser %s chost %s pkalg %s slen %zu", __func__,-
79 cuser, chost, pkalg, slen);-
80#ifdef DEBUG_PK-
81 debug("signature:");-
82 sshbuf_dump_data(sig, slen, stderr);-
83#endif-
84 pktype = sshkey_type_from_name(pkalg);-
85 if (pktype == KEY_UNSPEC) {
pktype == KEY_UNSPECDescription
TRUEnever evaluated
FALSEnever evaluated
0
86 /* this is perfectly legal */-
87 logit("%s: unsupported public key algorithm: %s",-
88 __func__, pkalg);-
89 goto done;
never executed: goto done;
0
90 }-
91 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
(r = sshkey_fr...n, &key)) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
92 error("%s: key_from_blob: %s", __func__, ssh_err(r));-
93 goto done;
never executed: goto done;
0
94 }-
95 if (key == NULL) {
key == ((void *)0)Description
TRUEnever evaluated
FALSEnever evaluated
0
96 error("%s: cannot decode key: %s", __func__, pkalg);-
97 goto done;
never executed: goto done;
0
98 }-
99 if (key->type != pktype) {
key->type != pktypeDescription
TRUEnever evaluated
FALSEnever evaluated
0
100 error("%s: type mismatch for decoded key "-
101 "(received %d, expected %d)", __func__, key->type, pktype);-
102 goto done;
never executed: goto done;
0
103 }-
104 if (sshkey_type_plain(key->type) == KEY_RSA &&
sshkey_type_pl...pe) == KEY_RSADescription
TRUEnever evaluated
FALSEnever evaluated
0
105 (ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
(ssh->compat &...00002000) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
106 error("Refusing RSA key because peer uses unsafe "-
107 "signature format");-
108 goto done;
never executed: goto done;
0
109 }-
110 if (match_pattern_list(pkalg, options.hostbased_key_types, 0) != 1) {
match_pattern_...types, 0) != 1Description
TRUEnever evaluated
FALSEnever evaluated
0
111 logit("%s: key type %s not in HostbasedAcceptedKeyTypes",-
112 __func__, sshkey_type(key));-
113 goto done;
never executed: goto done;
0
114 }-
115 if ((r = sshkey_check_cert_sigtype(key,
(r = sshkey_ch...orithms)) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
116 options.ca_sign_algorithms)) != 0) {
(r = sshkey_ch...orithms)) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
117 logit("%s: certificate signature algorithm %s: %s", __func__,-
118 (key->cert == NULL || key->cert->signature_type == NULL) ?-
119 "(null)" : key->cert->signature_type, ssh_err(r));-
120 goto done;
never executed: goto done;
0
121 }-
122-
123 if (!authctxt->valid || authctxt->user == NULL) {
!authctxt->validDescription
TRUEnever evaluated
FALSEnever evaluated
authctxt->user == ((void *)0)Description
TRUEnever evaluated
FALSEnever evaluated
0
124 debug2("%s: disabled because of invalid user", __func__);-
125 goto done;
never executed: goto done;
0
126 }-
127-
128 if ((b = sshbuf_new()) == NULL)
(b = sshbuf_ne...== ((void *)0)Description
TRUEnever evaluated
FALSEnever evaluated
0
129 fatal("%s: sshbuf_new failed", __func__);
never executed: fatal("%s: sshbuf_new failed", __func__);
0
130 /* reconstruct packet */-
131 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 ||
(r = sshbuf_pu...id2_len)) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
132 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
(r = sshbuf_pu...8(b, 50)) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
133 (r = sshbuf_put_cstring(b, authctxt->user)) != 0 ||
(r = sshbuf_pu...t->user)) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
134 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
(r = sshbuf_pu...service)) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
135 (r = sshbuf_put_cstring(b, "hostbased")) != 0 ||
(r = sshbuf_pu...tbased")) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
136 (r = sshbuf_put_string(b, pkalg, alen)) != 0 ||
(r = sshbuf_pu...g, alen)) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
137 (r = sshbuf_put_string(b, pkblob, blen)) != 0 ||
(r = sshbuf_pu...b, blen)) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
138 (r = sshbuf_put_cstring(b, chost)) != 0 ||
(r = sshbuf_pu..., chost)) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
139 (r = sshbuf_put_cstring(b, cuser)) != 0)
(r = sshbuf_pu..., cuser)) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
140 fatal("%s: buffer error: %s", __func__, ssh_err(r));
never executed: fatal("%s: buffer error: %s", __func__, ssh_err(r));
0
141#ifdef DEBUG_PK-
142 sshbuf_dump(b, stderr);-
143#endif-
144-
145 auth2_record_info(authctxt,-
146 "client user \"%.100s\", client host \"%.100s\"", cuser, chost);-
147-
148 /* test for allowed key and correct signature */-
149 authenticated = 0;-
150 if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
use_privsepDescription
TRUEnever evaluated
FALSEnever evaluated
(use_privsep ?..., chost, key))Description
TRUEnever evaluated
FALSEnever evaluated
0
151 PRIVSEP(sshkey_verify(key, sig, slen,
use_privsepDescription
TRUEnever evaluated
FALSEnever evaluated
(use_privsep ?...>compat)) == 0Description
TRUEnever evaluated
FALSEnever evaluated
0
152 sshbuf_ptr(b), sshbuf_len(b), pkalg, ssh->compat)) == 0)
(use_privsep ?...>compat)) == 0Description
TRUEnever evaluated
FALSEnever evaluated
0
153 authenticated = 1;
never executed: authenticated = 1;
0
154-
155 auth2_record_key(authctxt, authenticated, key);-
156 sshbuf_free(b);-
157done:
code before this statement never executed: done:
0
158 debug2("%s: authenticated %d", __func__, authenticated);-
159 sshkey_free(key);-
160 free(pkalg);-
161 free(pkblob);-
162 free(cuser);-
163 free(chost);-
164 free(sig);-
165 return authenticated;
never executed: return authenticated;
0
166}-
167-
168/* return 1 if given hostkey is allowed */-
169int-
170hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,-
171 struct sshkey *key)-
172{-
173 struct ssh *ssh = active_state; /* XXX */-
174 const char *resolvedname, *ipaddr, *lookup, *reason;-
175 HostStatus host_status;-
176 int len;-
177 char *fp;-
178-
179 if (auth_key_is_revoked(key))
auth_key_is_revoked(key)Description
TRUEnever evaluated
FALSEnever evaluated
0
180 return 0;
never executed: return 0;
0
181-
182 resolvedname = auth_get_canonical_hostname(ssh, options.use_dns);-
183 ipaddr = ssh_remote_ipaddr(ssh);-
184-
185 debug2("%s: chost %s resolvedname %s ipaddr %s", __func__,-
186 chost, resolvedname, ipaddr);-
187-
188 if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
((len = strlen(chost)) > 0)Description
TRUEnever evaluated
FALSEnever evaluated
chost[len - 1] == '.'Description
TRUEnever evaluated
FALSEnever evaluated
0
189 debug2("stripping trailing dot from chost %s", chost);-
190 chost[len - 1] = '\0';-
191 }
never executed: end of block
0
192-
193 if (options.hostbased_uses_name_from_packet_only) {
options.hostba...om_packet_onlyDescription
TRUEnever evaluated
FALSEnever evaluated
0
194 if (auth_rhosts2(pw, cuser, chost, chost) == 0) {
auth_rhosts2(p...t, chost) == 0Description
TRUEnever evaluated
FALSEnever evaluated
0
195 debug2("%s: auth_rhosts2 refused "-
196 "user \"%.100s\" host \"%.100s\" (from packet)",-
197 __func__, cuser, chost);-
198 return 0;
never executed: return 0;
0
199 }-
200 lookup = chost;-
201 } else {
never executed: end of block
0
202 if (strcasecmp(resolvedname, chost) != 0)
strcasecmp(res...e, chost) != 0Description
TRUEnever evaluated
FALSEnever evaluated
0
203 logit("userauth_hostbased mismatch: "
never executed: logit("userauth_hostbased mismatch: " "client sends %s, but we resolve %s to %s", chost, ipaddr, resolvedname);
0
204 "client sends %s, but we resolve %s to %s",
never executed: logit("userauth_hostbased mismatch: " "client sends %s, but we resolve %s to %s", chost, ipaddr, resolvedname);
0
205 chost, ipaddr, resolvedname);
never executed: logit("userauth_hostbased mismatch: " "client sends %s, but we resolve %s to %s", chost, ipaddr, resolvedname);
0
206 if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0) {
auth_rhosts2(p..., ipaddr) == 0Description
TRUEnever evaluated
FALSEnever evaluated
0
207 debug2("%s: auth_rhosts2 refused "-
208 "user \"%.100s\" host \"%.100s\" addr \"%.100s\"",-
209 __func__, cuser, resolvedname, ipaddr);-
210 return 0;
never executed: return 0;
0
211 }-
212 lookup = resolvedname;-
213 }
never executed: end of block
0
214 debug2("%s: access allowed by auth_rhosts2", __func__);-
215-
216 if (sshkey_is_cert(key) &&
sshkey_is_cert(key)Description
TRUEnever evaluated
FALSEnever evaluated
0
217 sshkey_cert_check_authority(key, 1, 0, lookup, &reason)) {
sshkey_cert_ch...okup, &reason)Description
TRUEnever evaluated
FALSEnever evaluated
0
218 error("%s", reason);-
219 auth_debug_add("%s", reason);-
220 return 0;
never executed: return 0;
0
221 }-
222-
223 host_status = check_key_in_hostfiles(pw, key, lookup,-
224 _PATH_SSH_SYSTEM_HOSTFILE,-
225 options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);-
226-
227 /* backward compat if no key has been found. */-
228 if (host_status == HOST_NEW) {
host_status == HOST_NEWDescription
TRUEnever evaluated
FALSEnever evaluated
0
229 host_status = check_key_in_hostfiles(pw, key, lookup,-
230 _PATH_SSH_SYSTEM_HOSTFILE2,-
231 options.ignore_user_known_hosts ? NULL :-
232 _PATH_SSH_USER_HOSTFILE2);-
233 }
never executed: end of block
0
234-
235 if (host_status == HOST_OK) {
host_status == HOST_OKDescription
TRUEnever evaluated
FALSEnever evaluated
0
236 if (sshkey_is_cert(key)) {
sshkey_is_cert(key)Description
TRUEnever evaluated
FALSEnever evaluated
0
237 if ((fp = sshkey_fingerprint(key->cert->signature_key,
(fp = sshkey_f...== ((void *)0)Description
TRUEnever evaluated
FALSEnever evaluated
0
238 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
(fp = sshkey_f...== ((void *)0)Description
TRUEnever evaluated
FALSEnever evaluated
0
239 fatal("%s: sshkey_fingerprint fail", __func__);
never executed: fatal("%s: sshkey_fingerprint fail", __func__);
0
240 verbose("Accepted certificate ID \"%s\" signed by "-
241 "%s CA %s from %s@%s", key->cert->key_id,-
242 sshkey_type(key->cert->signature_key), fp,-
243 cuser, lookup);-
244 } else {
never executed: end of block
0
245 if ((fp = sshkey_fingerprint(key,
(fp = sshkey_f...== ((void *)0)Description
TRUEnever evaluated
FALSEnever evaluated
0
246 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
(fp = sshkey_f...== ((void *)0)Description
TRUEnever evaluated
FALSEnever evaluated
0
247 fatal("%s: sshkey_fingerprint fail", __func__);
never executed: fatal("%s: sshkey_fingerprint fail", __func__);
0
248 verbose("Accepted %s public key %s from %s@%s",-
249 sshkey_type(key), fp, cuser, lookup);-
250 }
never executed: end of block
0
251 free(fp);-
252 }
never executed: end of block
0
253-
254 return (host_status == HOST_OK);
never executed: return (host_status == HOST_OK);
0
255}-
256-
257Authmethod method_hostbased = {-
258 "hostbased",-
259 userauth_hostbased,-
260 &options.hostbased_authentication-
261};-
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