2 * Copyright (c) 2000 Markus Friedl. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 RCSID("$OpenBSD: auth.c,v 1.51 2003/11/21 11:57:02 djm Exp $");
41 #include "groupaccess.h"
45 #include "auth-options.h"
50 #include "tildexpand.h"
56 extern ServerOptions options;
57 extern Buffer loginmsg;
59 /* Debugging messages */
64 * Check if the user is allowed to log in via ssh. If user is listed
65 * in DenyUsers or one of user's groups is listed in DenyGroups, false
66 * will be returned. If AllowUsers isn't empty and user isn't listed
67 * there, or if AllowGroups isn't empty and one of user's groups isn't
68 * listed there, false will be returned.
69 * If the user's shell is not executable, false will be returned.
70 * Otherwise true is returned.
73 allowed_user(struct passwd * pw)
76 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
80 struct spwd *spw = NULL;
83 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
84 if (!pw || !pw->pw_name)
89 spw = getspnam(pw->pw_name);
90 #ifdef HAS_SHADOW_EXPIRE
91 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
93 #endif /* HAS_SHADOW_EXPIRE */
94 #endif /* USE_SHADOW */
96 /* grab passwd field for locked account check */
99 passwd = spw->sp_pwdp;
101 passwd = pw->pw_passwd;
104 /* check for locked account */
105 if (!options.use_pam && passwd && *passwd) {
108 #ifdef LOCKED_PASSWD_STRING
109 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
112 #ifdef LOCKED_PASSWD_PREFIX
113 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
114 strlen(LOCKED_PASSWD_PREFIX)) == 0)
117 #ifdef LOCKED_PASSWD_SUBSTR
118 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
122 logit("User %.100s not allowed because account is locked",
129 * Get the shell from the password data. An empty shell field is
130 * legal, and means /bin/sh.
132 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
134 /* deny if shell does not exists or is not executable */
135 if (stat(shell, &st) != 0) {
136 logit("User %.100s not allowed because shell %.100s does not exist",
140 if (S_ISREG(st.st_mode) == 0 ||
141 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
142 logit("User %.100s not allowed because shell %.100s is not executable",
147 if (options.num_deny_users > 0 || options.num_allow_users > 0) {
148 hostname = get_canonical_hostname(options.use_dns);
149 ipaddr = get_remote_ipaddr();
152 /* Return false if user is listed in DenyUsers */
153 if (options.num_deny_users > 0) {
154 for (i = 0; i < options.num_deny_users; i++)
155 if (match_user(pw->pw_name, hostname, ipaddr,
156 options.deny_users[i])) {
157 logit("User %.100s not allowed because listed in DenyUsers",
162 /* Return false if AllowUsers isn't empty and user isn't listed there */
163 if (options.num_allow_users > 0) {
164 for (i = 0; i < options.num_allow_users; i++)
165 if (match_user(pw->pw_name, hostname, ipaddr,
166 options.allow_users[i]))
168 /* i < options.num_allow_users iff we break for loop */
169 if (i >= options.num_allow_users) {
170 logit("User %.100s not allowed because not listed in AllowUsers",
175 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
176 /* Get the user's group access list (primary and supplementary) */
177 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
178 logit("User %.100s not allowed because not in any group",
183 /* Return false if one of user's groups is listed in DenyGroups */
184 if (options.num_deny_groups > 0)
185 if (ga_match(options.deny_groups,
186 options.num_deny_groups)) {
188 logit("User %.100s not allowed because a group is listed in DenyGroups",
193 * Return false if AllowGroups isn't empty and one of user's groups
196 if (options.num_allow_groups > 0)
197 if (!ga_match(options.allow_groups,
198 options.num_allow_groups)) {
200 logit("User %.100s not allowed because none of user's groups are listed in AllowGroups",
207 #ifdef WITH_AIXAUTHENTICATE
209 * Don't check loginrestrictions() for root account (use
210 * PermitRootLogin to control logins via ssh), or if running as
211 * non-root user (since loginrestrictions will always fail).
213 if ((pw->pw_uid != 0) && (geteuid() == 0)) {
216 if (loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &msg) != 0) {
217 int loginrestrict_errno = errno;
220 buffer_append(&loginmsg, msg, strlen(msg));
221 aix_remove_embedded_newlines(msg);
222 logit("Login restricted for %s: %.100s",
225 /* Don't fail if /etc/nologin set */
226 if (!(loginrestrict_errno == EPERM &&
227 stat(_PATH_NOLOGIN, &st) == 0))
231 #endif /* WITH_AIXAUTHENTICATE */
233 /* We found no reason not to let this user try to log on... */
238 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
240 void (*authlog) (const char *fmt,...) = verbose;
243 /* Raise logging level */
244 if (authenticated == 1 ||
246 authctxt->failures >= AUTH_FAIL_LOG ||
247 strcmp(method, "password") == 0)
250 if (authctxt->postponed)
251 authmsg = "Postponed";
253 authmsg = authenticated ? "Accepted" : "Failed";
255 authlog("%s %s for %s%.100s from %.200s port %d%s",
258 authctxt->valid ? "" : "illegal user ",
259 (authctxt->user[0]) ? authctxt->user : "<implicit>",
264 #ifdef CUSTOM_FAILED_LOGIN
265 if (authenticated == 0 && strcmp(method, "password") == 0)
266 record_failed_login(authctxt->user, "ssh");
271 * Check whether root logins are disallowed.
274 auth_root_allowed(char *method)
276 switch (options.permit_root_login) {
280 case PERMIT_NO_PASSWD:
281 if (strcmp(method, "password") != 0)
284 case PERMIT_FORCED_ONLY:
285 if (forced_command) {
286 logit("Root login accepted for forced command.");
291 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
297 * Given a template and a passwd structure, build a filename
298 * by substituting % tokenised options. Currently, %% becomes '%',
299 * %h becomes the home directory and %u the username.
301 * This returns a buffer allocated by xmalloc.
304 expand_filename(const char *filename, struct passwd *pw)
311 * Build the filename string in the buffer by making the appropriate
312 * substitutions to the given file name.
314 buffer_init(&buffer);
315 for (cp = filename; *cp; cp++) {
316 if (cp[0] == '%' && cp[1] == '%') {
317 buffer_append(&buffer, "%", 1);
321 if (cp[0] == '%' && cp[1] == 'h') {
322 buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
326 if (cp[0] == '%' && cp[1] == 'u') {
327 buffer_append(&buffer, pw->pw_name,
328 strlen(pw->pw_name));
332 buffer_append(&buffer, cp, 1);
334 buffer_append(&buffer, "\0", 1);
337 * Ensure that filename starts anchored. If not, be backward
338 * compatible and prepend the '%h/'
340 file = xmalloc(MAXPATHLEN);
341 cp = buffer_ptr(&buffer);
343 snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
345 strlcpy(file, cp, MAXPATHLEN);
347 buffer_free(&buffer);
352 authorized_keys_file(struct passwd *pw)
354 return expand_filename(options.authorized_keys_file, pw);
358 authorized_keys_file2(struct passwd *pw)
360 return expand_filename(options.authorized_keys_file2, pw);
363 /* return ok if key exists in sysfile or userfile */
365 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
366 const char *sysfile, const char *userfile)
371 HostStatus host_status;
373 /* Check if we know the host and its host key. */
374 found = key_new(key->type);
375 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
377 if (host_status != HOST_OK && userfile != NULL) {
378 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
379 if (options.strict_modes &&
380 (stat(user_hostfile, &st) == 0) &&
381 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
382 (st.st_mode & 022) != 0)) {
383 logit("Authentication refused for %.100s: "
384 "bad owner or modes for %.200s",
385 pw->pw_name, user_hostfile);
387 temporarily_use_uid(pw);
388 host_status = check_host_in_hostfile(user_hostfile,
389 host, key, found, NULL);
392 xfree(user_hostfile);
396 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
397 "ok" : "not found", host);
403 * Check a given file for security. This is defined as all components
404 * of the path to the file must be owned by either the owner of
405 * of the file or root and no directories must be group or world writable.
407 * XXX Should any specific check be done for sym links ?
409 * Takes an open file descriptor, the file name, a uid and and
410 * error buffer plus max size as arguments.
412 * Returns 0 on success and -1 on failure
415 secure_filename(FILE *f, const char *file, struct passwd *pw,
416 char *err, size_t errlen)
418 uid_t uid = pw->pw_uid;
419 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
424 if (realpath(file, buf) == NULL) {
425 snprintf(err, errlen, "realpath %s failed: %s", file,
429 if (realpath(pw->pw_dir, homedir) != NULL)
432 /* check the open file to avoid races */
433 if (fstat(fileno(f), &st) < 0 ||
434 (st.st_uid != 0 && st.st_uid != uid) ||
435 (st.st_mode & 022) != 0) {
436 snprintf(err, errlen, "bad ownership or modes for file %s",
441 /* for each component of the canonical path, walking upwards */
443 if ((cp = dirname(buf)) == NULL) {
444 snprintf(err, errlen, "dirname() failed");
447 strlcpy(buf, cp, sizeof(buf));
449 debug3("secure_filename: checking '%s'", buf);
450 if (stat(buf, &st) < 0 ||
451 (st.st_uid != 0 && st.st_uid != uid) ||
452 (st.st_mode & 022) != 0) {
453 snprintf(err, errlen,
454 "bad ownership or modes for directory %s", buf);
458 /* If are passed the homedir then we can stop */
459 if (comparehome && strcmp(homedir, buf) == 0) {
460 debug3("secure_filename: terminating check at '%s'",
465 * dirname should always complete with a "/" path,
466 * but we can be paranoid and check for "." too
468 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
475 getpwnamallow(const char *user)
477 #ifdef HAVE_LOGIN_CAP
478 extern login_cap_t *lc;
487 logit("Illegal user %.100s from %.100s",
488 (user && user[0]) ? user : "<implicit>",
489 get_remote_ipaddr());
490 #ifdef CUSTOM_FAILED_LOGIN
491 record_failed_login(user, "ssh");
495 if (!allowed_user(pw))
497 #ifdef HAVE_LOGIN_CAP
498 if ((lc = login_getclass(pw->pw_class)) == NULL) {
499 debug("unable to get login class: %s", user);
503 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
504 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
505 debug("Approval failure for %s", user);
518 auth_debug_add(const char *fmt,...)
523 if (!auth_debug_init)
527 vsnprintf(buf, sizeof(buf), fmt, args);
529 buffer_put_cstring(&auth_debug, buf);
533 auth_debug_send(void)
537 if (!auth_debug_init)
539 while (buffer_len(&auth_debug)) {
540 msg = buffer_get_string(&auth_debug, NULL);
541 packet_send_debug("%s", msg);
547 auth_debug_reset(void)
550 buffer_clear(&auth_debug);
552 buffer_init(&auth_debug);
560 static struct passwd fake;
562 memset(&fake, 0, sizeof(fake));
563 fake.pw_name = "NOUSER";
565 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
566 fake.pw_gecos = "NOUSER";
569 #ifdef HAVE_PW_CLASS_IN_PASSWD
572 fake.pw_dir = "/nonexist";
573 fake.pw_shell = "/nonexist";