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>
51 #include "pathnames.h"
53 #include "auth-options.h"
58 #include "monitor_wrap.h"
64 extern ServerOptions options;
65 extern u_char *session_id2;
66 extern u_int session_id2_len;
69 userauth_pubkey(Authctxt *authctxt)
75 u_int alen, blen, slen;
77 int authenticated = 0;
79 if (!authctxt->valid) {
80 debug2("userauth_pubkey: disabled because of invalid user");
83 have_sig = packet_get_char();
84 if (datafellows & SSH_BUG_PKAUTH) {
85 debug2("userauth_pubkey: SSH_BUG_PKAUTH");
86 /* no explicit pkalg given */
87 pkblob = packet_get_string(&blen);
89 buffer_append(&b, pkblob, blen);
90 /* so we have to extract the pkalg from the pkblob */
91 pkalg = buffer_get_string(&b, &alen);
94 pkalg = packet_get_string(&alen);
95 pkblob = packet_get_string(&blen);
97 pktype = key_type_from_name(pkalg);
98 if (pktype == KEY_UNSPEC) {
99 /* this is perfectly legal */
100 logit("userauth_pubkey: unsupported public key algorithm: %s",
104 key = key_from_blob(pkblob, blen);
106 error("userauth_pubkey: cannot decode key: %s", pkalg);
109 if (key->type != pktype) {
110 error("userauth_pubkey: type mismatch for decoded key "
111 "(received %d, expected %d)", key->type, pktype);
115 sig = packet_get_string(&slen);
118 if (datafellows & SSH_OLD_SESSIONID) {
119 buffer_append(&b, session_id2, session_id2_len);
121 buffer_put_string(&b, session_id2, session_id2_len);
123 /* reconstruct packet */
124 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
125 buffer_put_cstring(&b, authctxt->user);
126 buffer_put_cstring(&b,
127 datafellows & SSH_BUG_PKSERVICE ?
130 if (datafellows & SSH_BUG_PKAUTH) {
131 buffer_put_char(&b, have_sig);
133 buffer_put_cstring(&b, "publickey");
134 buffer_put_char(&b, have_sig);
135 buffer_put_cstring(&b, pkalg);
137 buffer_put_string(&b, pkblob, blen);
141 /* test for correct signature */
143 if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
144 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
145 buffer_len(&b))) == 1)
150 debug("test whether pkalg/pkblob are acceptable");
153 /* XXX fake reply and always send PK_OK ? */
155 * XXX this allows testing whether a user is allowed
156 * to login: if you happen to have a valid pubkey this
157 * message is sent. the message is NEVER sent at all
158 * if a user is not allowed to login. is this an
161 if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
162 packet_start(SSH2_MSG_USERAUTH_PK_OK);
163 packet_put_string(pkalg, alen);
164 packet_put_string(pkblob, blen);
167 authctxt->postponed = 1;
170 if (authenticated != 1)
171 auth_clear_options();
173 debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
178 return authenticated;
182 match_principals_option(const char *principal_list, struct KeyCert *cert)
187 /* XXX percent_expand() sequences for authorized_principals? */
189 for (i = 0; i < cert->nprincipals; i++) {
190 if ((result = match_list(cert->principals[i],
191 principal_list, NULL)) != NULL) {
192 debug3("matched principal from key options \"%.100s\"",
202 match_principals_file(char *file, struct passwd *pw, struct KeyCert *cert)
205 char line[SSH_MAX_PUBKEY_BYTES], *cp, *ep, *line_opts;
209 temporarily_use_uid(pw);
210 debug("trying authorized principals file %s", file);
211 if ((f = auth_openprincipals(file, pw, options.strict_modes)) == NULL) {
215 while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
216 /* Skip leading whitespace. */
217 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
219 /* Skip blank and comment lines. */
220 if ((ep = strchr(cp, '#')) != NULL)
222 if (!*cp || *cp == '\n')
224 /* Trim trailing whitespace. */
225 ep = cp + strlen(cp) - 1;
226 while (ep > cp && (*ep == '\n' || *ep == ' ' || *ep == '\t'))
229 * If the line has internal whitespace then assume it has
233 if ((ep = strrchr(cp, ' ')) != NULL ||
234 (ep = strrchr(cp, '\t')) != NULL) {
235 for (; *ep == ' ' || *ep == '\t'; ep++)
240 for (i = 0; i < cert->nprincipals; i++) {
241 if (strcmp(cp, cert->principals[i]) == 0) {
242 debug3("matched principal \"%.100s\" "
243 "from file \"%s\" on line %lu",
244 cert->principals[i], file, linenum);
245 if (auth_parse_options(pw, line_opts,
259 /* return 1 if user allows given key */
261 user_key_allowed2(struct passwd *pw, Key *key, char *file)
263 char line[SSH_MAX_PUBKEY_BYTES];
271 /* Temporarily use the user's uid. */
272 temporarily_use_uid(pw);
274 debug("trying public key file %s", file);
275 f = auth_openkeyfile(file, pw, options.strict_modes);
283 found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
285 while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
286 char *cp, *key_options = NULL;
288 auth_clear_options();
290 /* Skip leading whitespace, empty and comment lines. */
291 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
293 if (!*cp || *cp == '\n' || *cp == '#')
296 if (key_read(found, &cp) != 1) {
297 /* no key? check if there are options for this key */
299 debug2("user_key_allowed: check options: '%s'", cp);
301 for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
302 if (*cp == '\\' && cp[1] == '"')
303 cp++; /* Skip both */
307 /* Skip remaining whitespace. */
308 for (; *cp == ' ' || *cp == '\t'; cp++)
310 if (key_read(found, &cp) != 1) {
311 debug2("user_key_allowed: advance: '%s'", cp);
312 /* still no key? advance to next line*/
316 if (key_is_cert(key)) {
317 if (!key_equal(found, key->cert->signature_key))
319 if (auth_parse_options(pw, key_options, file,
322 if (!key_is_cert_authority)
324 fp = key_fingerprint(found, SSH_FP_MD5,
326 debug("matching CA found: file %s, line %lu, %s %s",
327 file, linenum, key_type(found), fp);
329 * If the user has specified a list of principals as
330 * a key option, then prefer that list to matching
331 * their username in the certificate principals list.
333 if (authorized_principals != NULL &&
334 !match_principals_option(authorized_principals,
336 reason = "Certificate does not contain an "
337 "authorized principal";
341 auth_debug_add("%s", reason);
344 if (key_cert_check_authority(key, 0, 0,
345 authorized_principals == NULL ? pw->pw_name : NULL,
348 if (auth_cert_options(key, pw) != 0) {
352 verbose("Accepted certificate ID \"%s\" "
353 "signed by %s CA %s via %s", key->cert->key_id,
354 key_type(found), fp, file);
358 } else if (key_equal(found, key)) {
359 if (auth_parse_options(pw, key_options, file,
362 if (key_is_cert_authority)
365 debug("matching key found: file %s, line %lu",
367 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
368 verbose("Found matching %s key: %s",
369 key_type(found), fp);
378 debug2("key not found");
382 /* Authenticate a certificate key against TrustedUserCAKeys */
384 user_cert_trusted_ca(struct passwd *pw, Key *key)
386 char *ca_fp, *principals_file = NULL;
390 if (!key_is_cert(key) || options.trusted_user_ca_keys == NULL)
393 ca_fp = key_fingerprint(key->cert->signature_key,
394 SSH_FP_MD5, SSH_FP_HEX);
396 if (key_in_file(key->cert->signature_key,
397 options.trusted_user_ca_keys, 1) != 1) {
398 debug2("%s: CA %s %s is not listed in %s", __func__,
399 key_type(key->cert->signature_key), ca_fp,
400 options.trusted_user_ca_keys);
404 * If AuthorizedPrincipals is in use, then compare the certificate
405 * principals against the names in that file rather than matching
406 * against the username.
408 if ((principals_file = authorized_principals_file(pw)) != NULL) {
409 if (!match_principals_file(principals_file, pw, key->cert)) {
410 reason = "Certificate does not contain an "
411 "authorized principal";
414 auth_debug_add("%s", reason);
418 if (key_cert_check_authority(key, 0, 1,
419 principals_file == NULL ? pw->pw_name : NULL, &reason) != 0)
421 if (auth_cert_options(key, pw) != 0)
424 verbose("Accepted certificate ID \"%s\" signed by %s CA %s via %s",
425 key->cert->key_id, key_type(key->cert->signature_key), ca_fp,
426 options.trusted_user_ca_keys);
430 if (principals_file != NULL)
431 xfree(principals_file);
437 /* check whether given key is in .ssh/authorized_keys* */
439 user_key_allowed(struct passwd *pw, Key *key)
445 if (blacklisted_key(key)) {
446 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
447 if (options.permit_blacklisted_keys)
448 logit("Public key %s blacklisted (see "
449 "ssh-vulnkey(1)); continuing anyway", fp);
451 logit("Public key %s blacklisted (see "
452 "ssh-vulnkey(1))", fp);
454 if (!options.permit_blacklisted_keys)
458 if (auth_key_is_revoked(key))
460 if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
463 success = user_cert_trusted_ca(pw, key);
467 for (i = 0; !success && i < options.num_authkeys_files; i++) {
468 file = expand_authorized_keys(
469 options.authorized_keys_files[i], pw);
470 success = user_key_allowed2(pw, key, file);
477 Authmethod method_pubkey = {
480 &options.pubkey_authentication