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>
48 #include "pathnames.h"
50 #include "auth-options.h"
55 #include "monitor_wrap.h"
59 extern ServerOptions options;
60 extern u_char *session_id2;
61 extern u_int session_id2_len;
64 userauth_pubkey(Authctxt *authctxt)
70 u_int alen, blen, slen;
72 int authenticated = 0;
74 if (!authctxt->valid) {
75 debug2("userauth_pubkey: disabled because of invalid user");
78 have_sig = packet_get_char();
79 if (datafellows & SSH_BUG_PKAUTH) {
80 debug2("userauth_pubkey: SSH_BUG_PKAUTH");
81 /* no explicit pkalg given */
82 pkblob = packet_get_string(&blen);
84 buffer_append(&b, pkblob, blen);
85 /* so we have to extract the pkalg from the pkblob */
86 pkalg = buffer_get_string(&b, &alen);
89 pkalg = packet_get_string(&alen);
90 pkblob = packet_get_string(&blen);
92 pktype = key_type_from_name(pkalg);
93 if (pktype == KEY_UNSPEC) {
94 /* this is perfectly legal */
95 logit("userauth_pubkey: unsupported public key algorithm: %s",
99 key = key_from_blob(pkblob, blen);
101 error("userauth_pubkey: cannot decode key: %s", pkalg);
104 if (key->type != pktype) {
105 error("userauth_pubkey: type mismatch for decoded key "
106 "(received %d, expected %d)", key->type, pktype);
110 sig = packet_get_string(&slen);
113 if (datafellows & SSH_OLD_SESSIONID) {
114 buffer_append(&b, session_id2, session_id2_len);
116 buffer_put_string(&b, session_id2, session_id2_len);
118 /* reconstruct packet */
119 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
120 buffer_put_cstring(&b, authctxt->user);
121 buffer_put_cstring(&b,
122 datafellows & SSH_BUG_PKSERVICE ?
125 if (datafellows & SSH_BUG_PKAUTH) {
126 buffer_put_char(&b, have_sig);
128 buffer_put_cstring(&b, "publickey");
129 buffer_put_char(&b, have_sig);
130 buffer_put_cstring(&b, pkalg);
132 buffer_put_string(&b, pkblob, blen);
136 /* test for correct signature */
138 if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
139 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
140 buffer_len(&b))) == 1)
145 debug("test whether pkalg/pkblob are acceptable");
148 /* XXX fake reply and always send PK_OK ? */
150 * XXX this allows testing whether a user is allowed
151 * to login: if you happen to have a valid pubkey this
152 * message is sent. the message is NEVER sent at all
153 * if a user is not allowed to login. is this an
156 if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
157 packet_start(SSH2_MSG_USERAUTH_PK_OK);
158 packet_put_string(pkalg, alen);
159 packet_put_string(pkblob, blen);
162 authctxt->postponed = 1;
165 if (authenticated != 1)
166 auth_clear_options();
168 debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
174 if (check_nt_auth(0, authctxt->pw) == 0)
177 return authenticated;
180 /* return 1 if user allows given key */
182 user_key_allowed2(struct passwd *pw, Key *key, char *file)
184 char line[SSH_MAX_PUBKEY_BYTES];
191 /* Temporarily use the user's uid. */
192 temporarily_use_uid(pw);
194 debug("trying public key file %s", file);
195 f = auth_openkeyfile(file, pw, options.strict_modes);
203 found = key_new(key->type);
205 while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
206 char *cp, *key_options = NULL;
208 /* Skip leading whitespace, empty and comment lines. */
209 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
211 if (!*cp || *cp == '\n' || *cp == '#')
214 if (key_read(found, &cp) != 1) {
215 /* no key? check if there are options for this key */
217 debug2("user_key_allowed: check options: '%s'", cp);
219 for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
220 if (*cp == '\\' && cp[1] == '"')
221 cp++; /* Skip both */
225 /* Skip remaining whitespace. */
226 for (; *cp == ' ' || *cp == '\t'; cp++)
228 if (key_read(found, &cp) != 1) {
229 debug2("user_key_allowed: advance: '%s'", cp);
230 /* still no key? advance to next line*/
234 if (key_equal(found, key) &&
235 auth_parse_options(pw, key_options, file, linenum) == 1) {
237 debug("matching key found: file %s, line %lu",
239 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
240 verbose("Found matching %s key: %s",
241 key_type(found), fp);
250 debug2("key not found");
254 /* check whether given key is in .ssh/authorized_keys* */
256 user_key_allowed(struct passwd *pw, Key *key)
261 file = authorized_keys_file(pw);
262 success = user_key_allowed2(pw, key, file);
267 /* try suffix "2" for backward compat, too */
268 file = authorized_keys_file2(pw);
269 success = user_key_allowed2(pw, key, file);
274 Authmethod method_pubkey = {
277 &options.pubkey_authentication