1 /* $OpenBSD: auth2-pubkey.c,v 1.30 2011/09/25 05:44:47 djm 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>
50 #include "pathnames.h"
52 #include "auth-options.h"
57 #include "monitor_wrap.h"
63 extern ServerOptions options;
64 extern u_char *session_id2;
65 extern u_int session_id2_len;
68 userauth_pubkey(Authctxt *authctxt)
74 u_int alen, blen, slen;
76 int authenticated = 0;
78 if (!authctxt->valid) {
79 debug2("userauth_pubkey: disabled because of invalid user");
82 have_sig = packet_get_char();
83 if (datafellows & SSH_BUG_PKAUTH) {
84 debug2("userauth_pubkey: SSH_BUG_PKAUTH");
85 /* no explicit pkalg given */
86 pkblob = packet_get_string(&blen);
88 buffer_append(&b, pkblob, blen);
89 /* so we have to extract the pkalg from the pkblob */
90 pkalg = buffer_get_string(&b, &alen);
93 pkalg = packet_get_string(&alen);
94 pkblob = packet_get_string(&blen);
96 pktype = key_type_from_name(pkalg);
97 if (pktype == KEY_UNSPEC) {
98 /* this is perfectly legal */
99 logit("userauth_pubkey: unsupported public key algorithm: %s",
103 key = key_from_blob(pkblob, blen);
105 error("userauth_pubkey: cannot decode key: %s", pkalg);
108 if (key->type != pktype) {
109 error("userauth_pubkey: type mismatch for decoded key "
110 "(received %d, expected %d)", key->type, pktype);
114 sig = packet_get_string(&slen);
117 if (datafellows & SSH_OLD_SESSIONID) {
118 buffer_append(&b, session_id2, session_id2_len);
120 buffer_put_string(&b, session_id2, session_id2_len);
122 /* reconstruct packet */
123 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
124 buffer_put_cstring(&b, authctxt->user);
125 buffer_put_cstring(&b,
126 datafellows & SSH_BUG_PKSERVICE ?
129 if (datafellows & SSH_BUG_PKAUTH) {
130 buffer_put_char(&b, have_sig);
132 buffer_put_cstring(&b, "publickey");
133 buffer_put_char(&b, have_sig);
134 buffer_put_cstring(&b, pkalg);
136 buffer_put_string(&b, pkblob, blen);
140 /* test for correct signature */
142 if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
143 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
144 buffer_len(&b))) == 1)
149 debug("test whether pkalg/pkblob are acceptable");
152 /* XXX fake reply and always send PK_OK ? */
154 * XXX this allows testing whether a user is allowed
155 * to login: if you happen to have a valid pubkey this
156 * message is sent. the message is NEVER sent at all
157 * if a user is not allowed to login. is this an
160 if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
161 packet_start(SSH2_MSG_USERAUTH_PK_OK);
162 packet_put_string(pkalg, alen);
163 packet_put_string(pkblob, blen);
166 authctxt->postponed = 1;
169 if (authenticated != 1)
170 auth_clear_options();
172 debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
177 return authenticated;
181 match_principals_option(const char *principal_list, struct KeyCert *cert)
186 /* XXX percent_expand() sequences for authorized_principals? */
188 for (i = 0; i < cert->nprincipals; i++) {
189 if ((result = match_list(cert->principals[i],
190 principal_list, NULL)) != NULL) {
191 debug3("matched principal from key options \"%.100s\"",
201 match_principals_file(char *file, struct passwd *pw, struct KeyCert *cert)
204 char line[SSH_MAX_PUBKEY_BYTES], *cp, *ep, *line_opts;
208 temporarily_use_uid(pw);
209 debug("trying authorized principals file %s", file);
210 if ((f = auth_openprincipals(file, pw, options.strict_modes)) == NULL) {
214 while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
215 /* Skip leading whitespace. */
216 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
218 /* Skip blank and comment lines. */
219 if ((ep = strchr(cp, '#')) != NULL)
221 if (!*cp || *cp == '\n')
223 /* Trim trailing whitespace. */
224 ep = cp + strlen(cp) - 1;
225 while (ep > cp && (*ep == '\n' || *ep == ' ' || *ep == '\t'))
228 * If the line has internal whitespace then assume it has
232 if ((ep = strrchr(cp, ' ')) != NULL ||
233 (ep = strrchr(cp, '\t')) != NULL) {
234 for (; *ep == ' ' || *ep == '\t'; ep++)
239 for (i = 0; i < cert->nprincipals; i++) {
240 if (strcmp(cp, cert->principals[i]) == 0) {
241 debug3("matched principal \"%.100s\" "
242 "from file \"%s\" on line %lu",
243 cert->principals[i], file, linenum);
244 if (auth_parse_options(pw, line_opts,
258 /* return 1 if user allows given key */
260 user_key_allowed2(struct passwd *pw, Key *key, char *file)
262 char line[SSH_MAX_PUBKEY_BYTES];
270 /* Temporarily use the user's uid. */
271 temporarily_use_uid(pw);
273 debug("trying public key file %s", file);
274 f = auth_openkeyfile(file, pw, options.strict_modes);
282 found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
284 while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
285 char *cp, *key_options = NULL;
287 auth_clear_options();
289 /* Skip leading whitespace, empty and comment lines. */
290 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
292 if (!*cp || *cp == '\n' || *cp == '#')
295 if (key_read(found, &cp) != 1) {
296 /* no key? check if there are options for this key */
298 debug2("user_key_allowed: check options: '%s'", cp);
300 for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
301 if (*cp == '\\' && cp[1] == '"')
302 cp++; /* Skip both */
306 /* Skip remaining whitespace. */
307 for (; *cp == ' ' || *cp == '\t'; cp++)
309 if (key_read(found, &cp) != 1) {
310 debug2("user_key_allowed: advance: '%s'", cp);
311 /* still no key? advance to next line*/
315 if (key_is_cert(key)) {
316 if (!key_equal(found, key->cert->signature_key))
318 if (auth_parse_options(pw, key_options, file,
321 if (!key_is_cert_authority)
323 fp = key_fingerprint(found, SSH_FP_MD5,
325 debug("matching CA found: file %s, line %lu, %s %s",
326 file, linenum, key_type(found), fp);
328 * If the user has specified a list of principals as
329 * a key option, then prefer that list to matching
330 * their username in the certificate principals list.
332 if (authorized_principals != NULL &&
333 !match_principals_option(authorized_principals,
335 reason = "Certificate does not contain an "
336 "authorized principal";
340 auth_debug_add("%s", reason);
343 if (key_cert_check_authority(key, 0, 0,
344 authorized_principals == NULL ? pw->pw_name : NULL,
347 if (auth_cert_options(key, pw) != 0) {
351 verbose("Accepted certificate ID \"%s\" "
352 "signed by %s CA %s via %s", key->cert->key_id,
353 key_type(found), fp, file);
357 } else if (key_equal(found, key)) {
358 if (auth_parse_options(pw, key_options, file,
361 if (key_is_cert_authority)
364 debug("matching key found: file %s, line %lu",
366 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
367 verbose("Found matching %s key: %s",
368 key_type(found), fp);
377 debug2("key not found");
381 /* Authenticate a certificate key against TrustedUserCAKeys */
383 user_cert_trusted_ca(struct passwd *pw, Key *key)
385 char *ca_fp, *principals_file = NULL;
389 if (!key_is_cert(key) || options.trusted_user_ca_keys == NULL)
392 ca_fp = key_fingerprint(key->cert->signature_key,
393 SSH_FP_MD5, SSH_FP_HEX);
395 if (key_in_file(key->cert->signature_key,
396 options.trusted_user_ca_keys, 1) != 1) {
397 debug2("%s: CA %s %s is not listed in %s", __func__,
398 key_type(key->cert->signature_key), ca_fp,
399 options.trusted_user_ca_keys);
403 * If AuthorizedPrincipals is in use, then compare the certificate
404 * principals against the names in that file rather than matching
405 * against the username.
407 if ((principals_file = authorized_principals_file(pw)) != NULL) {
408 if (!match_principals_file(principals_file, pw, key->cert)) {
409 reason = "Certificate does not contain an "
410 "authorized principal";
413 auth_debug_add("%s", reason);
417 if (key_cert_check_authority(key, 0, 1,
418 principals_file == NULL ? pw->pw_name : NULL, &reason) != 0)
420 if (auth_cert_options(key, pw) != 0)
423 verbose("Accepted certificate ID \"%s\" signed by %s CA %s via %s",
424 key->cert->key_id, key_type(key->cert->signature_key), ca_fp,
425 options.trusted_user_ca_keys);
429 if (principals_file != NULL)
430 xfree(principals_file);
436 /* check whether given key is in .ssh/authorized_keys* */
438 user_key_allowed(struct passwd *pw, Key *key)
443 if (auth_key_is_revoked(key))
445 if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
448 success = user_cert_trusted_ca(pw, key);
452 for (i = 0; !success && i < options.num_authkeys_files; i++) {
453 file = expand_authorized_keys(
454 options.authorized_keys_files[i], pw);
455 success = user_key_allowed2(pw, key, file);
462 Authmethod method_pubkey = {
465 &options.pubkey_authentication