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 1.56 2004/07/28 09:40:29 markus Exp $");
41 #include "groupaccess.h"
45 #include "auth-options.h"
55 extern ServerOptions options;
56 extern Buffer loginmsg;
58 /* Debugging messages */
63 * Check if the user is allowed to log in via ssh. If user is listed
64 * in DenyUsers or one of user's groups is listed in DenyGroups, false
65 * will be returned. If AllowUsers isn't empty and user isn't listed
66 * there, or if AllowGroups isn't empty and one of user's groups isn't
67 * listed there, false will be returned.
68 * If the user's shell is not executable, false will be returned.
69 * Otherwise true is returned.
72 allowed_user(struct passwd * pw)
75 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
79 struct spwd *spw = NULL;
82 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
83 if (!pw || !pw->pw_name)
88 spw = getspnam(pw->pw_name);
89 #ifdef HAS_SHADOW_EXPIRE
90 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
92 #endif /* HAS_SHADOW_EXPIRE */
93 #endif /* USE_SHADOW */
95 /* grab passwd field for locked account check */
98 passwd = spw->sp_pwdp;
100 passwd = pw->pw_passwd;
103 /* check for locked account */
104 if (!options.use_pam && passwd && *passwd) {
107 #ifdef LOCKED_PASSWD_STRING
108 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
111 #ifdef LOCKED_PASSWD_PREFIX
112 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
113 strlen(LOCKED_PASSWD_PREFIX)) == 0)
116 #ifdef LOCKED_PASSWD_SUBSTR
117 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
121 logit("User %.100s not allowed because account is locked",
128 * Get the shell from the password data. An empty shell field is
129 * legal, and means /bin/sh.
131 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
133 /* deny if shell does not exists or is not executable */
134 if (stat(shell, &st) != 0) {
135 logit("User %.100s not allowed because shell %.100s does not exist",
139 if (S_ISREG(st.st_mode) == 0 ||
140 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
141 logit("User %.100s not allowed because shell %.100s is not executable",
146 if (options.num_deny_users > 0 || options.num_allow_users > 0) {
147 hostname = get_canonical_hostname(options.use_dns);
148 ipaddr = get_remote_ipaddr();
151 /* Return false if user is listed in DenyUsers */
152 if (options.num_deny_users > 0) {
153 for (i = 0; i < options.num_deny_users; i++)
154 if (match_user(pw->pw_name, hostname, ipaddr,
155 options.deny_users[i])) {
156 logit("User %.100s not allowed because listed in DenyUsers",
161 /* Return false if AllowUsers isn't empty and user isn't listed there */
162 if (options.num_allow_users > 0) {
163 for (i = 0; i < options.num_allow_users; i++)
164 if (match_user(pw->pw_name, hostname, ipaddr,
165 options.allow_users[i]))
167 /* i < options.num_allow_users iff we break for loop */
168 if (i >= options.num_allow_users) {
169 logit("User %.100s not allowed because not listed in AllowUsers",
174 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
175 /* Get the user's group access list (primary and supplementary) */
176 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
177 logit("User %.100s not allowed because not in any group",
182 /* Return false if one of user's groups is listed in DenyGroups */
183 if (options.num_deny_groups > 0)
184 if (ga_match(options.deny_groups,
185 options.num_deny_groups)) {
187 logit("User %.100s not allowed because a group is listed in DenyGroups",
192 * Return false if AllowGroups isn't empty and one of user's groups
195 if (options.num_allow_groups > 0)
196 if (!ga_match(options.allow_groups,
197 options.num_allow_groups)) {
199 logit("User %.100s not allowed because none of user's groups are listed in AllowGroups",
206 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
207 if (!sys_auth_allowed_user(pw))
211 /* We found no reason not to let this user try to log on... */
216 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
218 void (*authlog) (const char *fmt,...) = verbose;
221 /* Raise logging level */
222 if (authenticated == 1 ||
224 authctxt->failures >= options.max_authtries / 2 ||
225 strcmp(method, "password") == 0)
228 if (authctxt->postponed)
229 authmsg = "Postponed";
231 authmsg = authenticated ? "Accepted" : "Failed";
233 authlog("%s %s for %s%.100s from %.200s port %d%s",
236 authctxt->valid ? "" : "invalid user ",
237 (authctxt->user && authctxt->user[0]) ?
238 authctxt->user : "<implicit>",
243 #ifdef CUSTOM_FAILED_LOGIN
244 if (authenticated == 0 && strcmp(method, "password") == 0)
245 record_failed_login(authctxt->user, "ssh");
250 * Check whether root logins are disallowed.
253 auth_root_allowed(char *method)
255 switch (options.permit_root_login) {
259 case PERMIT_NO_PASSWD:
260 if (strcmp(method, "password") != 0)
263 case PERMIT_FORCED_ONLY:
264 if (forced_command) {
265 logit("Root login accepted for forced command.");
270 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
276 * Given a template and a passwd structure, build a filename
277 * by substituting % tokenised options. Currently, %% becomes '%',
278 * %h becomes the home directory and %u the username.
280 * This returns a buffer allocated by xmalloc.
283 expand_filename(const char *filename, struct passwd *pw)
290 * Build the filename string in the buffer by making the appropriate
291 * substitutions to the given file name.
293 buffer_init(&buffer);
294 for (cp = filename; *cp; cp++) {
295 if (cp[0] == '%' && cp[1] == '%') {
296 buffer_append(&buffer, "%", 1);
300 if (cp[0] == '%' && cp[1] == 'h') {
301 buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
305 if (cp[0] == '%' && cp[1] == 'u') {
306 buffer_append(&buffer, pw->pw_name,
307 strlen(pw->pw_name));
311 buffer_append(&buffer, cp, 1);
313 buffer_append(&buffer, "\0", 1);
316 * Ensure that filename starts anchored. If not, be backward
317 * compatible and prepend the '%h/'
319 file = xmalloc(MAXPATHLEN);
320 cp = buffer_ptr(&buffer);
322 snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
324 strlcpy(file, cp, MAXPATHLEN);
326 buffer_free(&buffer);
331 authorized_keys_file(struct passwd *pw)
333 return expand_filename(options.authorized_keys_file, pw);
337 authorized_keys_file2(struct passwd *pw)
339 return expand_filename(options.authorized_keys_file2, pw);
342 /* return ok if key exists in sysfile or userfile */
344 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
345 const char *sysfile, const char *userfile)
350 HostStatus host_status;
352 /* Check if we know the host and its host key. */
353 found = key_new(key->type);
354 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
356 if (host_status != HOST_OK && userfile != NULL) {
357 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
358 if (options.strict_modes &&
359 (stat(user_hostfile, &st) == 0) &&
360 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
361 (st.st_mode & 022) != 0)) {
362 logit("Authentication refused for %.100s: "
363 "bad owner or modes for %.200s",
364 pw->pw_name, user_hostfile);
366 temporarily_use_uid(pw);
367 host_status = check_host_in_hostfile(user_hostfile,
368 host, key, found, NULL);
371 xfree(user_hostfile);
375 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
376 "ok" : "not found", host);
382 * Check a given file for security. This is defined as all components
383 * of the path to the file must be owned by either the owner of
384 * of the file or root and no directories must be group or world writable.
386 * XXX Should any specific check be done for sym links ?
388 * Takes an open file descriptor, the file name, a uid and and
389 * error buffer plus max size as arguments.
391 * Returns 0 on success and -1 on failure
394 secure_filename(FILE *f, const char *file, struct passwd *pw,
395 char *err, size_t errlen)
397 uid_t uid = pw->pw_uid;
398 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
403 if (realpath(file, buf) == NULL) {
404 snprintf(err, errlen, "realpath %s failed: %s", file,
408 if (realpath(pw->pw_dir, homedir) != NULL)
411 /* check the open file to avoid races */
412 if (fstat(fileno(f), &st) < 0 ||
413 (st.st_uid != 0 && st.st_uid != uid) ||
414 (st.st_mode & 022) != 0) {
415 snprintf(err, errlen, "bad ownership or modes for file %s",
420 /* for each component of the canonical path, walking upwards */
422 if ((cp = dirname(buf)) == NULL) {
423 snprintf(err, errlen, "dirname() failed");
426 strlcpy(buf, cp, sizeof(buf));
428 debug3("secure_filename: checking '%s'", buf);
429 if (stat(buf, &st) < 0 ||
430 (st.st_uid != 0 && st.st_uid != uid) ||
431 (st.st_mode & 022) != 0) {
432 snprintf(err, errlen,
433 "bad ownership or modes for directory %s", buf);
437 /* If are passed the homedir then we can stop */
438 if (comparehome && strcmp(homedir, buf) == 0) {
439 debug3("secure_filename: terminating check at '%s'",
444 * dirname should always complete with a "/" path,
445 * but we can be paranoid and check for "." too
447 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
454 getpwnamallow(const char *user)
456 #ifdef HAVE_LOGIN_CAP
457 extern login_cap_t *lc;
466 logit("Invalid user %.100s from %.100s",
467 (user && user[0]) ? user : "<implicit>",
468 get_remote_ipaddr());
469 #ifdef CUSTOM_FAILED_LOGIN
470 record_failed_login(user, "ssh");
474 if (!allowed_user(pw))
476 #ifdef HAVE_LOGIN_CAP
477 if ((lc = login_getclass(pw->pw_class)) == NULL) {
478 debug("unable to get login class: %s", user);
482 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
483 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
484 debug("Approval failure for %s", user);
497 auth_debug_add(const char *fmt,...)
502 if (!auth_debug_init)
506 vsnprintf(buf, sizeof(buf), fmt, args);
508 buffer_put_cstring(&auth_debug, buf);
512 auth_debug_send(void)
516 if (!auth_debug_init)
518 while (buffer_len(&auth_debug)) {
519 msg = buffer_get_string(&auth_debug, NULL);
520 packet_send_debug("%s", msg);
526 auth_debug_reset(void)
529 buffer_clear(&auth_debug);
531 buffer_init(&auth_debug);
539 static struct passwd fake;
541 memset(&fake, 0, sizeof(fake));
542 fake.pw_name = "NOUSER";
544 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
545 fake.pw_gecos = "NOUSER";
546 fake.pw_uid = (uid_t)-1;
547 fake.pw_gid = (gid_t)-1;
548 #ifdef HAVE_PW_CLASS_IN_PASSWD
551 fake.pw_dir = "/nonexist";
552 fake.pw_shell = "/nonexist";