1 /* $OpenBSD: auth2-pubkey.c,v 1.19 2008/07/03 21:46:58 otto Exp $ */
3 * Copyright (c) 2000 Markus Friedl. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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.
28 #include <sys/types.h>
49 #include "pathnames.h"
51 #include "auth-options.h"
56 #include "monitor_wrap.h"
60 extern ServerOptions options;
61 extern u_char *session_id2;
62 extern u_int session_id2_len;
65 userauth_pubkey(Authctxt *authctxt)
71 u_int alen, blen, slen;
73 int authenticated = 0;
75 if (!authctxt->valid) {
76 debug2("userauth_pubkey: disabled because of invalid user");
79 have_sig = packet_get_char();
80 if (datafellows & SSH_BUG_PKAUTH) {
81 debug2("userauth_pubkey: SSH_BUG_PKAUTH");
82 /* no explicit pkalg given */
83 pkblob = packet_get_string(&blen);
85 buffer_append(&b, pkblob, blen);
86 /* so we have to extract the pkalg from the pkblob */
87 pkalg = buffer_get_string(&b, &alen);
90 pkalg = packet_get_string(&alen);
91 pkblob = packet_get_string(&blen);
93 pktype = key_type_from_name(pkalg);
94 if (pktype == KEY_UNSPEC) {
95 /* this is perfectly legal */
96 logit("userauth_pubkey: unsupported public key algorithm: %s",
100 key = key_from_blob(pkblob, blen);
102 error("userauth_pubkey: cannot decode key: %s", pkalg);
105 if (key->type != pktype) {
106 error("userauth_pubkey: type mismatch for decoded key "
107 "(received %d, expected %d)", key->type, pktype);
111 sig = packet_get_string(&slen);
114 if (datafellows & SSH_OLD_SESSIONID) {
115 buffer_append(&b, session_id2, session_id2_len);
117 buffer_put_string(&b, session_id2, session_id2_len);
119 /* reconstruct packet */
120 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
121 buffer_put_cstring(&b, authctxt->user);
122 buffer_put_cstring(&b,
123 datafellows & SSH_BUG_PKSERVICE ?
126 if (datafellows & SSH_BUG_PKAUTH) {
127 buffer_put_char(&b, have_sig);
129 buffer_put_cstring(&b, "publickey");
130 buffer_put_char(&b, have_sig);
131 buffer_put_cstring(&b, pkalg);
133 buffer_put_string(&b, pkblob, blen);
137 /* test for correct signature */
139 if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
140 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
141 buffer_len(&b))) == 1)
146 debug("test whether pkalg/pkblob are acceptable");
149 /* XXX fake reply and always send PK_OK ? */
151 * XXX this allows testing whether a user is allowed
152 * to login: if you happen to have a valid pubkey this
153 * message is sent. the message is NEVER sent at all
154 * if a user is not allowed to login. is this an
157 if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
158 packet_start(SSH2_MSG_USERAUTH_PK_OK);
159 packet_put_string(pkalg, alen);
160 packet_put_string(pkblob, blen);
163 authctxt->postponed = 1;
166 if (authenticated != 1)
167 auth_clear_options();
169 debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
175 if (check_nt_auth(0, authctxt->pw) == 0)
178 return authenticated;
181 /* return 1 if user allows given key */
183 user_key_allowed2(struct passwd *pw, Key *key, char *file)
185 char line[SSH_MAX_PUBKEY_BYTES];
192 /* Temporarily use the user's uid. */
193 temporarily_use_uid(pw);
195 debug("trying public key file %s", file);
196 f = auth_openkeyfile(file, pw, options.strict_modes);
204 found = key_new(key->type);
206 while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
207 char *cp, *key_options = NULL;
209 /* Skip leading whitespace, empty and comment lines. */
210 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
212 if (!*cp || *cp == '\n' || *cp == '#')
215 if (key_read(found, &cp) != 1) {
216 /* no key? check if there are options for this key */
218 debug2("user_key_allowed: check options: '%s'", cp);
220 for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
221 if (*cp == '\\' && cp[1] == '"')
222 cp++; /* Skip both */
226 /* Skip remaining whitespace. */
227 for (; *cp == ' ' || *cp == '\t'; cp++)
229 if (key_read(found, &cp) != 1) {
230 debug2("user_key_allowed: advance: '%s'", cp);
231 /* still no key? advance to next line*/
235 if (key_equal(found, key) &&
236 auth_parse_options(pw, key_options, file, linenum) == 1) {
238 debug("matching key found: file %s, line %lu",
240 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
241 verbose("Found matching %s key: %s",
242 key_type(found), fp);
251 debug2("key not found");
255 /* check whether given key is in .ssh/authorized_keys* */
257 user_key_allowed(struct passwd *pw, Key *key)
263 if (blacklisted_key(key)) {
264 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
265 if (options.permit_blacklisted_keys)
266 logit("Public key %s blacklisted (see "
267 "ssh-vulnkey(1)); continuing anyway", fp);
269 logit("Public key %s blacklisted (see "
270 "ssh-vulnkey(1))", fp);
272 if (!options.permit_blacklisted_keys)
276 file = authorized_keys_file(pw);
277 success = user_key_allowed2(pw, key, file);
282 /* try suffix "2" for backward compat, too */
283 file = authorized_keys_file2(pw);
284 success = user_key_allowed2(pw, key, file);
289 Authmethod method_pubkey = {
292 &options.pubkey_authentication