1 /* $OpenBSD: auth2-pubkey.c,v 1.13 2006/07/06 16:03:53 stevesk 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>
44 #include "pathnames.h"
46 #include "auth-options.h"
48 #include "monitor_wrap.h"
52 extern ServerOptions options;
53 extern u_char *session_id2;
54 extern u_int session_id2_len;
57 userauth_pubkey(Authctxt *authctxt)
63 u_int alen, blen, slen;
65 int authenticated = 0;
67 if (!authctxt->valid) {
68 debug2("userauth_pubkey: disabled because of invalid user");
71 have_sig = packet_get_char();
72 if (datafellows & SSH_BUG_PKAUTH) {
73 debug2("userauth_pubkey: SSH_BUG_PKAUTH");
74 /* no explicit pkalg given */
75 pkblob = packet_get_string(&blen);
77 buffer_append(&b, pkblob, blen);
78 /* so we have to extract the pkalg from the pkblob */
79 pkalg = buffer_get_string(&b, &alen);
82 pkalg = packet_get_string(&alen);
83 pkblob = packet_get_string(&blen);
85 pktype = key_type_from_name(pkalg);
86 if (pktype == KEY_UNSPEC) {
87 /* this is perfectly legal */
88 logit("userauth_pubkey: unsupported public key algorithm: %s",
92 key = key_from_blob(pkblob, blen);
94 error("userauth_pubkey: cannot decode key: %s", pkalg);
97 if (key->type != pktype) {
98 error("userauth_pubkey: type mismatch for decoded key "
99 "(received %d, expected %d)", key->type, pktype);
103 sig = packet_get_string(&slen);
106 if (datafellows & SSH_OLD_SESSIONID) {
107 buffer_append(&b, session_id2, session_id2_len);
109 buffer_put_string(&b, session_id2, session_id2_len);
111 /* reconstruct packet */
112 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
113 buffer_put_cstring(&b, authctxt->user);
114 buffer_put_cstring(&b,
115 datafellows & SSH_BUG_PKSERVICE ?
118 if (datafellows & SSH_BUG_PKAUTH) {
119 buffer_put_char(&b, have_sig);
121 buffer_put_cstring(&b, "publickey");
122 buffer_put_char(&b, have_sig);
123 buffer_put_cstring(&b, pkalg);
125 buffer_put_string(&b, pkblob, blen);
129 /* test for correct signature */
131 if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
132 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
133 buffer_len(&b))) == 1)
138 debug("test whether pkalg/pkblob are acceptable");
141 /* XXX fake reply and always send PK_OK ? */
143 * XXX this allows testing whether a user is allowed
144 * to login: if you happen to have a valid pubkey this
145 * message is sent. the message is NEVER sent at all
146 * if a user is not allowed to login. is this an
149 if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
150 packet_start(SSH2_MSG_USERAUTH_PK_OK);
151 packet_put_string(pkalg, alen);
152 packet_put_string(pkblob, blen);
155 authctxt->postponed = 1;
158 if (authenticated != 1)
159 auth_clear_options();
161 debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
167 if (check_nt_auth(0, authctxt->pw) == 0)
170 return authenticated;
173 /* return 1 if user allows given key */
175 user_key_allowed2(struct passwd *pw, Key *key, char *file)
177 char line[SSH_MAX_PUBKEY_BYTES];
185 /* Temporarily use the user's uid. */
186 temporarily_use_uid(pw);
188 debug("trying public key file %s", file);
190 /* Fail quietly if file does not exist */
191 if (stat(file, &st) < 0) {
192 /* Restore the privileged uid. */
196 /* Open the file containing the authorized keys. */
197 f = fopen(file, "r");
199 /* Restore the privileged uid. */
203 if (options.strict_modes &&
204 secure_filename(f, file, pw, line, sizeof(line)) != 0) {
206 logit("Authentication refused: %s", line);
212 found = key_new(key->type);
214 while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
215 char *cp, *key_options = NULL;
217 /* Skip leading whitespace, empty and comment lines. */
218 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
220 if (!*cp || *cp == '\n' || *cp == '#')
223 if (key_read(found, &cp) != 1) {
224 /* no key? check if there are options for this key */
226 debug2("user_key_allowed: check options: '%s'", cp);
228 for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
229 if (*cp == '\\' && cp[1] == '"')
230 cp++; /* Skip both */
234 /* Skip remaining whitespace. */
235 for (; *cp == ' ' || *cp == '\t'; cp++)
237 if (key_read(found, &cp) != 1) {
238 debug2("user_key_allowed: advance: '%s'", cp);
239 /* still no key? advance to next line*/
243 if (key_equal(found, key) &&
244 auth_parse_options(pw, key_options, file, linenum) == 1) {
246 debug("matching key found: file %s, line %lu",
248 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
249 verbose("Found matching %s key: %s",
250 key_type(found), fp);
259 debug2("key not found");
263 /* check whether given key is in .ssh/authorized_keys* */
265 user_key_allowed(struct passwd *pw, Key *key)
270 file = authorized_keys_file(pw);
271 success = user_key_allowed2(pw, key, file);
276 /* try suffix "2" for backward compat, too */
277 file = authorized_keys_file2(pw);
278 success = user_key_allowed2(pw, key, file);
283 Authmethod method_pubkey = {
286 &options.pubkey_authentication