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 1.57 2005/01/22 08:17:59 dtucker Exp $");
41 #include "groupaccess.h"
45 #include "auth-options.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 from %.100s not allowed "
158 "because listed in DenyUsers",
159 pw->pw_name, hostname);
163 /* Return false if AllowUsers isn't empty and user isn't listed there */
164 if (options.num_allow_users > 0) {
165 for (i = 0; i < options.num_allow_users; i++)
166 if (match_user(pw->pw_name, hostname, ipaddr,
167 options.allow_users[i]))
169 /* i < options.num_allow_users iff we break for loop */
170 if (i >= options.num_allow_users) {
171 logit("User %.100s from %.100s not allowed because "
172 "not listed in AllowUsers", pw->pw_name, hostname);
176 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
177 /* Get the user's group access list (primary and supplementary) */
178 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
179 logit("User %.100s from %.100s not allowed because "
180 "not in any group", pw->pw_name, hostname);
184 /* Return false if one of user's groups is listed in DenyGroups */
185 if (options.num_deny_groups > 0)
186 if (ga_match(options.deny_groups,
187 options.num_deny_groups)) {
189 logit("User %.100s from %.100s not allowed "
190 "because a group is listed in DenyGroups",
191 pw->pw_name, hostname);
195 * Return false if AllowGroups isn't empty and one of user's groups
198 if (options.num_allow_groups > 0)
199 if (!ga_match(options.allow_groups,
200 options.num_allow_groups)) {
202 logit("User %.100s from %.100s not allowed "
203 "because none of user's groups are listed "
204 "in AllowGroups", pw->pw_name, hostname);
210 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
211 if (!sys_auth_allowed_user(pw))
215 /* We found no reason not to let this user try to log on... */
220 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
222 void (*authlog) (const char *fmt,...) = verbose;
225 /* Raise logging level */
226 if (authenticated == 1 ||
228 authctxt->failures >= options.max_authtries / 2 ||
229 strcmp(method, "password") == 0)
232 if (authctxt->postponed)
233 authmsg = "Postponed";
235 authmsg = authenticated ? "Accepted" : "Failed";
237 authlog("%s %s for %s%.100s from %.200s port %d%s",
240 authctxt->valid ? "" : "invalid user ",
246 #ifdef CUSTOM_FAILED_LOGIN
247 if (authenticated == 0 && !authctxt->postponed &&
248 (strcmp(method, "password") == 0 ||
249 strncmp(method, "keyboard-interactive", 20) == 0) ||
250 strcmp(method, "challenge-response") == 0)
251 record_failed_login(authctxt->user,
252 get_canonical_hostname(options.use_dns), "ssh");
257 * Check whether root logins are disallowed.
260 auth_root_allowed(char *method)
262 switch (options.permit_root_login) {
266 case PERMIT_NO_PASSWD:
267 if (strcmp(method, "password") != 0)
270 case PERMIT_FORCED_ONLY:
271 if (forced_command) {
272 logit("Root login accepted for forced command.");
277 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
283 * Given a template and a passwd structure, build a filename
284 * by substituting % tokenised options. Currently, %% becomes '%',
285 * %h becomes the home directory and %u the username.
287 * This returns a buffer allocated by xmalloc.
290 expand_filename(const char *filename, struct passwd *pw)
297 * Build the filename string in the buffer by making the appropriate
298 * substitutions to the given file name.
300 buffer_init(&buffer);
301 for (cp = filename; *cp; cp++) {
302 if (cp[0] == '%' && cp[1] == '%') {
303 buffer_append(&buffer, "%", 1);
307 if (cp[0] == '%' && cp[1] == 'h') {
308 buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
312 if (cp[0] == '%' && cp[1] == 'u') {
313 buffer_append(&buffer, pw->pw_name,
314 strlen(pw->pw_name));
318 buffer_append(&buffer, cp, 1);
320 buffer_append(&buffer, "\0", 1);
323 * Ensure that filename starts anchored. If not, be backward
324 * compatible and prepend the '%h/'
326 file = xmalloc(MAXPATHLEN);
327 cp = buffer_ptr(&buffer);
329 snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
331 strlcpy(file, cp, MAXPATHLEN);
333 buffer_free(&buffer);
338 authorized_keys_file(struct passwd *pw)
340 return expand_filename(options.authorized_keys_file, pw);
344 authorized_keys_file2(struct passwd *pw)
346 return expand_filename(options.authorized_keys_file2, pw);
349 /* return ok if key exists in sysfile or userfile */
351 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
352 const char *sysfile, const char *userfile)
357 HostStatus host_status;
359 /* Check if we know the host and its host key. */
360 found = key_new(key->type);
361 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
363 if (host_status != HOST_OK && userfile != NULL) {
364 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
365 if (options.strict_modes &&
366 (stat(user_hostfile, &st) == 0) &&
367 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
368 (st.st_mode & 022) != 0)) {
369 logit("Authentication refused for %.100s: "
370 "bad owner or modes for %.200s",
371 pw->pw_name, user_hostfile);
373 temporarily_use_uid(pw);
374 host_status = check_host_in_hostfile(user_hostfile,
375 host, key, found, NULL);
378 xfree(user_hostfile);
382 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
383 "ok" : "not found", host);
389 * Check a given file for security. This is defined as all components
390 * of the path to the file must be owned by either the owner of
391 * of the file or root and no directories must be group or world writable.
393 * XXX Should any specific check be done for sym links ?
395 * Takes an open file descriptor, the file name, a uid and and
396 * error buffer plus max size as arguments.
398 * Returns 0 on success and -1 on failure
401 secure_filename(FILE *f, const char *file, struct passwd *pw,
402 char *err, size_t errlen)
404 uid_t uid = pw->pw_uid;
405 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
410 if (realpath(file, buf) == NULL) {
411 snprintf(err, errlen, "realpath %s failed: %s", file,
415 if (realpath(pw->pw_dir, homedir) != NULL)
418 /* check the open file to avoid races */
419 if (fstat(fileno(f), &st) < 0 ||
420 (st.st_uid != 0 && st.st_uid != uid) ||
421 (st.st_mode & 022) != 0) {
422 snprintf(err, errlen, "bad ownership or modes for file %s",
427 /* for each component of the canonical path, walking upwards */
429 if ((cp = dirname(buf)) == NULL) {
430 snprintf(err, errlen, "dirname() failed");
433 strlcpy(buf, cp, sizeof(buf));
435 debug3("secure_filename: checking '%s'", buf);
436 if (stat(buf, &st) < 0 ||
437 (st.st_uid != 0 && st.st_uid != uid) ||
438 (st.st_mode & 022) != 0) {
439 snprintf(err, errlen,
440 "bad ownership or modes for directory %s", buf);
444 /* If are passed the homedir then we can stop */
445 if (comparehome && strcmp(homedir, buf) == 0) {
446 debug3("secure_filename: terminating check at '%s'",
451 * dirname should always complete with a "/" path,
452 * but we can be paranoid and check for "." too
454 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
461 getpwnamallow(const char *user)
463 #ifdef HAVE_LOGIN_CAP
464 extern login_cap_t *lc;
473 logit("Invalid user %.100s from %.100s",
474 user, get_remote_ipaddr());
475 #ifdef CUSTOM_FAILED_LOGIN
476 record_failed_login(user,
477 get_canonical_hostname(options.use_dns), "ssh");
481 if (!allowed_user(pw))
483 #ifdef HAVE_LOGIN_CAP
484 if ((lc = login_getclass(pw->pw_class)) == NULL) {
485 debug("unable to get login class: %s", user);
489 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
490 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
491 debug("Approval failure for %s", user);
504 auth_debug_add(const char *fmt,...)
509 if (!auth_debug_init)
513 vsnprintf(buf, sizeof(buf), fmt, args);
515 buffer_put_cstring(&auth_debug, buf);
519 auth_debug_send(void)
523 if (!auth_debug_init)
525 while (buffer_len(&auth_debug)) {
526 msg = buffer_get_string(&auth_debug, NULL);
527 packet_send_debug("%s", msg);
533 auth_debug_reset(void)
536 buffer_clear(&auth_debug);
538 buffer_init(&auth_debug);
546 static struct passwd fake;
548 memset(&fake, 0, sizeof(fake));
549 fake.pw_name = "NOUSER";
551 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
552 fake.pw_gecos = "NOUSER";
553 fake.pw_uid = (uid_t)-1;
554 fake.pw_gid = (gid_t)-1;
555 #ifdef HAVE_PW_CLASS_IN_PASSWD
558 fake.pw_dir = "/nonexist";
559 fake.pw_shell = "/nonexist";