1 /* $OpenBSD: auth.c,v 1.67 2006/03/30 11:40:21 dtucker 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>
47 #include "groupaccess.h"
51 #include "auth-options.h"
60 #include "monitor_wrap.h"
63 extern ServerOptions options;
64 extern int use_privsep;
65 extern Buffer loginmsg;
67 /* Debugging messages */
72 * Check if the user is allowed to log in via ssh. If user is listed
73 * in DenyUsers or one of user's groups is listed in DenyGroups, false
74 * will be returned. If AllowUsers isn't empty and user isn't listed
75 * there, or if AllowGroups isn't empty and one of user's groups isn't
76 * listed there, false will be returned.
77 * If the user's shell is not executable, false will be returned.
78 * Otherwise true is returned.
81 allowed_user(struct passwd * pw)
84 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
88 struct spwd *spw = NULL;
91 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
92 if (!pw || !pw->pw_name)
97 spw = getspnam(pw->pw_name);
98 #ifdef HAS_SHADOW_EXPIRE
99 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
101 #endif /* HAS_SHADOW_EXPIRE */
102 #endif /* USE_SHADOW */
104 /* grab passwd field for locked account check */
107 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
108 passwd = get_iaf_password(pw);
110 passwd = spw->sp_pwdp;
111 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
113 passwd = pw->pw_passwd;
116 /* check for locked account */
117 if (!options.use_pam && passwd && *passwd) {
120 #ifdef LOCKED_PASSWD_STRING
121 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
124 #ifdef LOCKED_PASSWD_PREFIX
125 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
126 strlen(LOCKED_PASSWD_PREFIX)) == 0)
129 #ifdef LOCKED_PASSWD_SUBSTR
130 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
133 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
135 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
137 logit("User %.100s not allowed because account is locked",
144 * Get the shell from the password data. An empty shell field is
145 * legal, and means /bin/sh.
147 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
149 /* deny if shell does not exists or is not executable */
150 if (stat(shell, &st) != 0) {
151 logit("User %.100s not allowed because shell %.100s does not exist",
155 if (S_ISREG(st.st_mode) == 0 ||
156 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
157 logit("User %.100s not allowed because shell %.100s is not executable",
162 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
163 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
164 hostname = get_canonical_hostname(options.use_dns);
165 ipaddr = get_remote_ipaddr();
168 /* Return false if user is listed in DenyUsers */
169 if (options.num_deny_users > 0) {
170 for (i = 0; i < options.num_deny_users; i++)
171 if (match_user(pw->pw_name, hostname, ipaddr,
172 options.deny_users[i])) {
173 logit("User %.100s from %.100s not allowed "
174 "because listed in DenyUsers",
175 pw->pw_name, hostname);
179 /* Return false if AllowUsers isn't empty and user isn't listed there */
180 if (options.num_allow_users > 0) {
181 for (i = 0; i < options.num_allow_users; i++)
182 if (match_user(pw->pw_name, hostname, ipaddr,
183 options.allow_users[i]))
185 /* i < options.num_allow_users iff we break for loop */
186 if (i >= options.num_allow_users) {
187 logit("User %.100s from %.100s not allowed because "
188 "not listed in AllowUsers", pw->pw_name, hostname);
192 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
193 /* Get the user's group access list (primary and supplementary) */
194 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
195 logit("User %.100s from %.100s not allowed because "
196 "not in any group", pw->pw_name, hostname);
200 /* Return false if one of user's groups is listed in DenyGroups */
201 if (options.num_deny_groups > 0)
202 if (ga_match(options.deny_groups,
203 options.num_deny_groups)) {
205 logit("User %.100s from %.100s not allowed "
206 "because a group is listed in DenyGroups",
207 pw->pw_name, hostname);
211 * Return false if AllowGroups isn't empty and one of user's groups
214 if (options.num_allow_groups > 0)
215 if (!ga_match(options.allow_groups,
216 options.num_allow_groups)) {
218 logit("User %.100s from %.100s not allowed "
219 "because none of user's groups are listed "
220 "in AllowGroups", pw->pw_name, hostname);
226 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
227 if (!sys_auth_allowed_user(pw, &loginmsg))
231 /* We found no reason not to let this user try to log on... */
236 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
238 void (*authlog) (const char *fmt,...) = verbose;
241 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
244 /* Raise logging level */
245 if (authenticated == 1 ||
247 authctxt->failures >= options.max_authtries / 2 ||
248 strcmp(method, "password") == 0)
251 if (authctxt->postponed)
252 authmsg = "Postponed";
254 authmsg = authenticated ? "Accepted" : "Failed";
256 authlog("%s %s for %s%.100s from %.200s port %d%s",
259 authctxt->valid ? "" : "invalid user ",
265 #ifdef CUSTOM_FAILED_LOGIN
266 if (authenticated == 0 && !authctxt->postponed &&
267 (strcmp(method, "password") == 0 ||
268 strncmp(method, "keyboard-interactive", 20) == 0 ||
269 strcmp(method, "challenge-response") == 0))
270 record_failed_login(authctxt->user,
271 get_canonical_hostname(options.use_dns), "ssh");
273 #ifdef SSH_AUDIT_EVENTS
274 if (authenticated == 0 && !authctxt->postponed)
275 audit_event(audit_classify_auth(method));
280 * Check whether root logins are disallowed.
283 auth_root_allowed(char *method)
285 switch (options.permit_root_login) {
288 case PERMIT_NO_PASSWD:
289 if (strcmp(method, "password") != 0)
292 case PERMIT_FORCED_ONLY:
293 if (forced_command) {
294 logit("Root login accepted for forced command.");
299 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
305 * Given a template and a passwd structure, build a filename
306 * by substituting % tokenised options. Currently, %% becomes '%',
307 * %h becomes the home directory and %u the username.
309 * This returns a buffer allocated by xmalloc.
312 expand_authorized_keys(const char *filename, struct passwd *pw)
314 char *file, ret[MAXPATHLEN];
317 file = percent_expand(filename, "h", pw->pw_dir,
318 "u", pw->pw_name, (char *)NULL);
321 * Ensure that filename starts anchored. If not, be backward
322 * compatible and prepend the '%h/'
327 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
328 if (i < 0 || (size_t)i >= sizeof(ret))
329 fatal("expand_authorized_keys: path too long");
331 return (xstrdup(ret));
335 authorized_keys_file(struct passwd *pw)
337 return expand_authorized_keys(options.authorized_keys_file, pw);
341 authorized_keys_file2(struct passwd *pw)
343 return expand_authorized_keys(options.authorized_keys_file2, pw);
346 /* return ok if key exists in sysfile or userfile */
348 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
349 const char *sysfile, const char *userfile)
354 HostStatus host_status;
356 /* Check if we know the host and its host key. */
357 found = key_new(key->type);
358 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
360 if (host_status != HOST_OK && userfile != NULL) {
361 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
362 if (options.strict_modes &&
363 (stat(user_hostfile, &st) == 0) &&
364 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
365 (st.st_mode & 022) != 0)) {
366 logit("Authentication refused for %.100s: "
367 "bad owner or modes for %.200s",
368 pw->pw_name, user_hostfile);
370 temporarily_use_uid(pw);
371 host_status = check_host_in_hostfile(user_hostfile,
372 host, key, found, NULL);
375 xfree(user_hostfile);
379 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
380 "ok" : "not found", host);
386 * Check a given file for security. This is defined as all components
387 * of the path to the file must be owned by either the owner of
388 * of the file or root and no directories must be group or world writable.
390 * XXX Should any specific check be done for sym links ?
392 * Takes an open file descriptor, the file name, a uid and and
393 * error buffer plus max size as arguments.
395 * Returns 0 on success and -1 on failure
398 secure_filename(FILE *f, const char *file, struct passwd *pw,
399 char *err, size_t errlen)
401 uid_t uid = pw->pw_uid;
402 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
407 if (realpath(file, buf) == NULL) {
408 snprintf(err, errlen, "realpath %s failed: %s", file,
412 if (realpath(pw->pw_dir, homedir) != NULL)
415 /* check the open file to avoid races */
416 if (fstat(fileno(f), &st) < 0 ||
417 (st.st_uid != 0 && st.st_uid != uid) ||
418 (st.st_mode & 022) != 0) {
419 snprintf(err, errlen, "bad ownership or modes for file %s",
424 /* for each component of the canonical path, walking upwards */
426 if ((cp = dirname(buf)) == NULL) {
427 snprintf(err, errlen, "dirname() failed");
430 strlcpy(buf, cp, sizeof(buf));
432 debug3("secure_filename: checking '%s'", buf);
433 if (stat(buf, &st) < 0 ||
434 (st.st_uid != 0 && st.st_uid != uid) ||
435 (st.st_mode & 022) != 0) {
436 snprintf(err, errlen,
437 "bad ownership or modes for directory %s", buf);
441 /* If are passed the homedir then we can stop */
442 if (comparehome && strcmp(homedir, buf) == 0) {
443 debug3("secure_filename: terminating check at '%s'",
448 * dirname should always complete with a "/" path,
449 * but we can be paranoid and check for "." too
451 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
458 getpwnamallow(const char *user)
460 #ifdef HAVE_LOGIN_CAP
461 extern login_cap_t *lc;
470 logit("Invalid user %.100s from %.100s",
471 user, get_remote_ipaddr());
472 #ifdef CUSTOM_FAILED_LOGIN
473 record_failed_login(user,
474 get_canonical_hostname(options.use_dns), "ssh");
476 #ifdef SSH_AUDIT_EVENTS
477 audit_event(SSH_INVALID_USER);
478 #endif /* SSH_AUDIT_EVENTS */
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";