1 /* $OpenBSD: auth.c,v 1.73 2006/07/26 02:35:17 stevesk 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>
30 #include <sys/param.h>
51 #include "groupaccess.h"
55 #include "auth-options.h"
64 #include "monitor_wrap.h"
67 extern ServerOptions options;
68 extern int use_privsep;
69 extern Buffer loginmsg;
71 /* Debugging messages */
76 * Check if the user is allowed to log in via ssh. If user is listed
77 * in DenyUsers or one of user's groups is listed in DenyGroups, false
78 * will be returned. If AllowUsers isn't empty and user isn't listed
79 * there, or if AllowGroups isn't empty and one of user's groups isn't
80 * listed there, false will be returned.
81 * If the user's shell is not executable, false will be returned.
82 * Otherwise true is returned.
85 allowed_user(struct passwd * pw)
88 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
92 struct spwd *spw = NULL;
95 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
96 if (!pw || !pw->pw_name)
100 if (!options.use_pam)
101 spw = getspnam(pw->pw_name);
102 #ifdef HAS_SHADOW_EXPIRE
103 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
105 #endif /* HAS_SHADOW_EXPIRE */
106 #endif /* USE_SHADOW */
108 /* grab passwd field for locked account check */
111 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
112 passwd = get_iaf_password(pw);
114 passwd = spw->sp_pwdp;
115 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
117 passwd = pw->pw_passwd;
120 /* check for locked account */
121 if (!options.use_pam && passwd && *passwd) {
124 #ifdef LOCKED_PASSWD_STRING
125 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
128 #ifdef LOCKED_PASSWD_PREFIX
129 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
130 strlen(LOCKED_PASSWD_PREFIX)) == 0)
133 #ifdef LOCKED_PASSWD_SUBSTR
134 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
137 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
139 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
141 logit("User %.100s not allowed because account is locked",
148 * Get the shell from the password data. An empty shell field is
149 * legal, and means /bin/sh.
151 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
153 /* deny if shell does not exists or is not executable */
154 if (stat(shell, &st) != 0) {
155 logit("User %.100s not allowed because shell %.100s does not exist",
159 if (S_ISREG(st.st_mode) == 0 ||
160 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
161 logit("User %.100s not allowed because shell %.100s is not executable",
166 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
167 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
168 hostname = get_canonical_hostname(options.use_dns);
169 ipaddr = get_remote_ipaddr();
172 /* Return false if user is listed in DenyUsers */
173 if (options.num_deny_users > 0) {
174 for (i = 0; i < options.num_deny_users; i++)
175 if (match_user(pw->pw_name, hostname, ipaddr,
176 options.deny_users[i])) {
177 logit("User %.100s from %.100s not allowed "
178 "because listed in DenyUsers",
179 pw->pw_name, hostname);
183 /* Return false if AllowUsers isn't empty and user isn't listed there */
184 if (options.num_allow_users > 0) {
185 for (i = 0; i < options.num_allow_users; i++)
186 if (match_user(pw->pw_name, hostname, ipaddr,
187 options.allow_users[i]))
189 /* i < options.num_allow_users iff we break for loop */
190 if (i >= options.num_allow_users) {
191 logit("User %.100s from %.100s not allowed because "
192 "not listed in AllowUsers", pw->pw_name, hostname);
196 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
197 /* Get the user's group access list (primary and supplementary) */
198 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
199 logit("User %.100s from %.100s not allowed because "
200 "not in any group", pw->pw_name, hostname);
204 /* Return false if one of user's groups is listed in DenyGroups */
205 if (options.num_deny_groups > 0)
206 if (ga_match(options.deny_groups,
207 options.num_deny_groups)) {
209 logit("User %.100s from %.100s not allowed "
210 "because a group is listed in DenyGroups",
211 pw->pw_name, hostname);
215 * Return false if AllowGroups isn't empty and one of user's groups
218 if (options.num_allow_groups > 0)
219 if (!ga_match(options.allow_groups,
220 options.num_allow_groups)) {
222 logit("User %.100s from %.100s not allowed "
223 "because none of user's groups are listed "
224 "in AllowGroups", pw->pw_name, hostname);
230 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
231 if (!sys_auth_allowed_user(pw, &loginmsg))
235 /* We found no reason not to let this user try to log on... */
240 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
242 void (*authlog) (const char *fmt,...) = verbose;
245 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
248 /* Raise logging level */
249 if (authenticated == 1 ||
251 authctxt->failures >= options.max_authtries / 2 ||
252 strcmp(method, "password") == 0)
255 if (authctxt->postponed)
256 authmsg = "Postponed";
258 authmsg = authenticated ? "Accepted" : "Failed";
260 authlog("%s %s for %s%.100s from %.200s port %d%s",
263 authctxt->valid ? "" : "invalid user ",
269 #ifdef CUSTOM_FAILED_LOGIN
270 if (authenticated == 0 && !authctxt->postponed &&
271 (strcmp(method, "password") == 0 ||
272 strncmp(method, "keyboard-interactive", 20) == 0 ||
273 strcmp(method, "challenge-response") == 0))
274 record_failed_login(authctxt->user,
275 get_canonical_hostname(options.use_dns), "ssh");
277 #ifdef SSH_AUDIT_EVENTS
278 if (authenticated == 0 && !authctxt->postponed)
279 audit_event(audit_classify_auth(method));
284 * Check whether root logins are disallowed.
287 auth_root_allowed(char *method)
289 switch (options.permit_root_login) {
292 case PERMIT_NO_PASSWD:
293 if (strcmp(method, "password") != 0)
296 case PERMIT_FORCED_ONLY:
297 if (forced_command) {
298 logit("Root login accepted for forced command.");
303 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
309 * Given a template and a passwd structure, build a filename
310 * by substituting % tokenised options. Currently, %% becomes '%',
311 * %h becomes the home directory and %u the username.
313 * This returns a buffer allocated by xmalloc.
316 expand_authorized_keys(const char *filename, struct passwd *pw)
318 char *file, ret[MAXPATHLEN];
321 file = percent_expand(filename, "h", pw->pw_dir,
322 "u", pw->pw_name, (char *)NULL);
325 * Ensure that filename starts anchored. If not, be backward
326 * compatible and prepend the '%h/'
331 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
332 if (i < 0 || (size_t)i >= sizeof(ret))
333 fatal("expand_authorized_keys: path too long");
335 return (xstrdup(ret));
339 authorized_keys_file(struct passwd *pw)
341 return expand_authorized_keys(options.authorized_keys_file, pw);
345 authorized_keys_file2(struct passwd *pw)
347 return expand_authorized_keys(options.authorized_keys_file2, pw);
350 /* return ok if key exists in sysfile or userfile */
352 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
353 const char *sysfile, const char *userfile)
358 HostStatus host_status;
360 /* Check if we know the host and its host key. */
361 found = key_new(key->type);
362 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
364 if (host_status != HOST_OK && userfile != NULL) {
365 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
366 if (options.strict_modes &&
367 (stat(user_hostfile, &st) == 0) &&
368 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
369 (st.st_mode & 022) != 0)) {
370 logit("Authentication refused for %.100s: "
371 "bad owner or modes for %.200s",
372 pw->pw_name, user_hostfile);
374 temporarily_use_uid(pw);
375 host_status = check_host_in_hostfile(user_hostfile,
376 host, key, found, NULL);
379 xfree(user_hostfile);
383 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
384 "ok" : "not found", host);
390 * Check a given file for security. This is defined as all components
391 * of the path to the file must be owned by either the owner of
392 * of the file or root and no directories must be group or world writable.
394 * XXX Should any specific check be done for sym links ?
396 * Takes an open file descriptor, the file name, a uid and and
397 * error buffer plus max size as arguments.
399 * Returns 0 on success and -1 on failure
402 secure_filename(FILE *f, const char *file, struct passwd *pw,
403 char *err, size_t errlen)
405 uid_t uid = pw->pw_uid;
406 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
411 if (realpath(file, buf) == NULL) {
412 snprintf(err, errlen, "realpath %s failed: %s", file,
416 if (realpath(pw->pw_dir, homedir) != NULL)
419 /* check the open file to avoid races */
420 if (fstat(fileno(f), &st) < 0 ||
421 (st.st_uid != 0 && st.st_uid != uid) ||
422 (st.st_mode & 022) != 0) {
423 snprintf(err, errlen, "bad ownership or modes for file %s",
428 /* for each component of the canonical path, walking upwards */
430 if ((cp = dirname(buf)) == NULL) {
431 snprintf(err, errlen, "dirname() failed");
434 strlcpy(buf, cp, sizeof(buf));
436 debug3("secure_filename: checking '%s'", buf);
437 if (stat(buf, &st) < 0 ||
438 (st.st_uid != 0 && st.st_uid != uid) ||
439 (st.st_mode & 022) != 0) {
440 snprintf(err, errlen,
441 "bad ownership or modes for directory %s", buf);
445 /* If are passed the homedir then we can stop */
446 if (comparehome && strcmp(homedir, buf) == 0) {
447 debug3("secure_filename: terminating check at '%s'",
452 * dirname should always complete with a "/" path,
453 * but we can be paranoid and check for "." too
455 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
462 getpwnamallow(const char *user)
464 #ifdef HAVE_LOGIN_CAP
465 extern login_cap_t *lc;
472 parse_server_match_config(&options, user,
473 get_canonical_hostname(options.use_dns), get_remote_ipaddr());
477 logit("Invalid user %.100s from %.100s",
478 user, get_remote_ipaddr());
479 #ifdef CUSTOM_FAILED_LOGIN
480 record_failed_login(user,
481 get_canonical_hostname(options.use_dns), "ssh");
483 #ifdef SSH_AUDIT_EVENTS
484 audit_event(SSH_INVALID_USER);
485 #endif /* SSH_AUDIT_EVENTS */
488 if (!allowed_user(pw))
490 #ifdef HAVE_LOGIN_CAP
491 if ((lc = login_getclass(pw->pw_class)) == NULL) {
492 debug("unable to get login class: %s", user);
496 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
497 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
498 debug("Approval failure for %s", user);
511 auth_debug_add(const char *fmt,...)
516 if (!auth_debug_init)
520 vsnprintf(buf, sizeof(buf), fmt, args);
522 buffer_put_cstring(&auth_debug, buf);
526 auth_debug_send(void)
530 if (!auth_debug_init)
532 while (buffer_len(&auth_debug)) {
533 msg = buffer_get_string(&auth_debug, NULL);
534 packet_send_debug("%s", msg);
540 auth_debug_reset(void)
543 buffer_clear(&auth_debug);
545 buffer_init(&auth_debug);
553 static struct passwd fake;
555 memset(&fake, 0, sizeof(fake));
556 fake.pw_name = "NOUSER";
558 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
559 fake.pw_gecos = "NOUSER";
560 fake.pw_uid = (uid_t)-1;
561 fake.pw_gid = (gid_t)-1;
562 #ifdef HAVE_PW_CLASS_IN_PASSWD
565 fake.pw_dir = "/nonexist";
566 fake.pw_shell = "/nonexist";