1 /* $OpenBSD: auth.c,v 1.70 2006/07/11 20:07:25 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>
49 #include "groupaccess.h"
53 #include "auth-options.h"
62 #include "monitor_wrap.h"
65 extern ServerOptions options;
66 extern int use_privsep;
67 extern Buffer loginmsg;
69 /* Debugging messages */
74 * Check if the user is allowed to log in via ssh. If user is listed
75 * in DenyUsers or one of user's groups is listed in DenyGroups, false
76 * will be returned. If AllowUsers isn't empty and user isn't listed
77 * there, or if AllowGroups isn't empty and one of user's groups isn't
78 * listed there, false will be returned.
79 * If the user's shell is not executable, false will be returned.
80 * Otherwise true is returned.
83 allowed_user(struct passwd * pw)
86 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
90 struct spwd *spw = NULL;
93 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
94 if (!pw || !pw->pw_name)
99 spw = getspnam(pw->pw_name);
100 #ifdef HAS_SHADOW_EXPIRE
101 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
103 #endif /* HAS_SHADOW_EXPIRE */
104 #endif /* USE_SHADOW */
106 /* grab passwd field for locked account check */
109 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
110 passwd = get_iaf_password(pw);
112 passwd = spw->sp_pwdp;
113 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
115 passwd = pw->pw_passwd;
118 /* check for locked account */
119 if (!options.use_pam && passwd && *passwd) {
122 #ifdef LOCKED_PASSWD_STRING
123 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
126 #ifdef LOCKED_PASSWD_PREFIX
127 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
128 strlen(LOCKED_PASSWD_PREFIX)) == 0)
131 #ifdef LOCKED_PASSWD_SUBSTR
132 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
135 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
137 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
139 logit("User %.100s not allowed because account is locked",
146 * Get the shell from the password data. An empty shell field is
147 * legal, and means /bin/sh.
149 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
151 /* deny if shell does not exists or is not executable */
152 if (stat(shell, &st) != 0) {
153 logit("User %.100s not allowed because shell %.100s does not exist",
157 if (S_ISREG(st.st_mode) == 0 ||
158 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
159 logit("User %.100s not allowed because shell %.100s is not executable",
164 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
165 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
166 hostname = get_canonical_hostname(options.use_dns);
167 ipaddr = get_remote_ipaddr();
170 /* Return false if user is listed in DenyUsers */
171 if (options.num_deny_users > 0) {
172 for (i = 0; i < options.num_deny_users; i++)
173 if (match_user(pw->pw_name, hostname, ipaddr,
174 options.deny_users[i])) {
175 logit("User %.100s from %.100s not allowed "
176 "because listed in DenyUsers",
177 pw->pw_name, hostname);
181 /* Return false if AllowUsers isn't empty and user isn't listed there */
182 if (options.num_allow_users > 0) {
183 for (i = 0; i < options.num_allow_users; i++)
184 if (match_user(pw->pw_name, hostname, ipaddr,
185 options.allow_users[i]))
187 /* i < options.num_allow_users iff we break for loop */
188 if (i >= options.num_allow_users) {
189 logit("User %.100s from %.100s not allowed because "
190 "not listed in AllowUsers", pw->pw_name, hostname);
194 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
195 /* Get the user's group access list (primary and supplementary) */
196 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
197 logit("User %.100s from %.100s not allowed because "
198 "not in any group", pw->pw_name, hostname);
202 /* Return false if one of user's groups is listed in DenyGroups */
203 if (options.num_deny_groups > 0)
204 if (ga_match(options.deny_groups,
205 options.num_deny_groups)) {
207 logit("User %.100s from %.100s not allowed "
208 "because a group is listed in DenyGroups",
209 pw->pw_name, hostname);
213 * Return false if AllowGroups isn't empty and one of user's groups
216 if (options.num_allow_groups > 0)
217 if (!ga_match(options.allow_groups,
218 options.num_allow_groups)) {
220 logit("User %.100s from %.100s not allowed "
221 "because none of user's groups are listed "
222 "in AllowGroups", pw->pw_name, hostname);
228 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
229 if (!sys_auth_allowed_user(pw, &loginmsg))
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 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
246 /* Raise logging level */
247 if (authenticated == 1 ||
249 authctxt->failures >= options.max_authtries / 2 ||
250 strcmp(method, "password") == 0)
253 if (authctxt->postponed)
254 authmsg = "Postponed";
256 authmsg = authenticated ? "Accepted" : "Failed";
258 authlog("%s %s for %s%.100s from %.200s port %d%s",
261 authctxt->valid ? "" : "invalid user ",
267 #ifdef CUSTOM_FAILED_LOGIN
268 if (authenticated == 0 && !authctxt->postponed &&
269 (strcmp(method, "password") == 0 ||
270 strncmp(method, "keyboard-interactive", 20) == 0 ||
271 strcmp(method, "challenge-response") == 0))
272 record_failed_login(authctxt->user,
273 get_canonical_hostname(options.use_dns), "ssh");
275 #ifdef SSH_AUDIT_EVENTS
276 if (authenticated == 0 && !authctxt->postponed)
277 audit_event(audit_classify_auth(method));
282 * Check whether root logins are disallowed.
285 auth_root_allowed(char *method)
287 switch (options.permit_root_login) {
290 case PERMIT_NO_PASSWD:
291 if (strcmp(method, "password") != 0)
294 case PERMIT_FORCED_ONLY:
295 if (forced_command) {
296 logit("Root login accepted for forced command.");
301 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
307 * Given a template and a passwd structure, build a filename
308 * by substituting % tokenised options. Currently, %% becomes '%',
309 * %h becomes the home directory and %u the username.
311 * This returns a buffer allocated by xmalloc.
314 expand_authorized_keys(const char *filename, struct passwd *pw)
316 char *file, ret[MAXPATHLEN];
319 file = percent_expand(filename, "h", pw->pw_dir,
320 "u", pw->pw_name, (char *)NULL);
323 * Ensure that filename starts anchored. If not, be backward
324 * compatible and prepend the '%h/'
329 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
330 if (i < 0 || (size_t)i >= sizeof(ret))
331 fatal("expand_authorized_keys: path too long");
333 return (xstrdup(ret));
337 authorized_keys_file(struct passwd *pw)
339 return expand_authorized_keys(options.authorized_keys_file, pw);
343 authorized_keys_file2(struct passwd *pw)
345 return expand_authorized_keys(options.authorized_keys_file2, pw);
348 /* return ok if key exists in sysfile or userfile */
350 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
351 const char *sysfile, const char *userfile)
356 HostStatus host_status;
358 /* Check if we know the host and its host key. */
359 found = key_new(key->type);
360 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
362 if (host_status != HOST_OK && userfile != NULL) {
363 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
364 if (options.strict_modes &&
365 (stat(user_hostfile, &st) == 0) &&
366 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
367 (st.st_mode & 022) != 0)) {
368 logit("Authentication refused for %.100s: "
369 "bad owner or modes for %.200s",
370 pw->pw_name, user_hostfile);
372 temporarily_use_uid(pw);
373 host_status = check_host_in_hostfile(user_hostfile,
374 host, key, found, NULL);
377 xfree(user_hostfile);
381 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
382 "ok" : "not found", host);
388 * Check a given file for security. This is defined as all components
389 * of the path to the file must be owned by either the owner of
390 * of the file or root and no directories must be group or world writable.
392 * XXX Should any specific check be done for sym links ?
394 * Takes an open file descriptor, the file name, a uid and and
395 * error buffer plus max size as arguments.
397 * Returns 0 on success and -1 on failure
400 secure_filename(FILE *f, const char *file, struct passwd *pw,
401 char *err, size_t errlen)
403 uid_t uid = pw->pw_uid;
404 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
409 if (realpath(file, buf) == NULL) {
410 snprintf(err, errlen, "realpath %s failed: %s", file,
414 if (realpath(pw->pw_dir, homedir) != NULL)
417 /* check the open file to avoid races */
418 if (fstat(fileno(f), &st) < 0 ||
419 (st.st_uid != 0 && st.st_uid != uid) ||
420 (st.st_mode & 022) != 0) {
421 snprintf(err, errlen, "bad ownership or modes for file %s",
426 /* for each component of the canonical path, walking upwards */
428 if ((cp = dirname(buf)) == NULL) {
429 snprintf(err, errlen, "dirname() failed");
432 strlcpy(buf, cp, sizeof(buf));
434 debug3("secure_filename: checking '%s'", buf);
435 if (stat(buf, &st) < 0 ||
436 (st.st_uid != 0 && st.st_uid != uid) ||
437 (st.st_mode & 022) != 0) {
438 snprintf(err, errlen,
439 "bad ownership or modes for directory %s", buf);
443 /* If are passed the homedir then we can stop */
444 if (comparehome && strcmp(homedir, buf) == 0) {
445 debug3("secure_filename: terminating check at '%s'",
450 * dirname should always complete with a "/" path,
451 * but we can be paranoid and check for "." too
453 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
460 getpwnamallow(const char *user)
462 #ifdef HAVE_LOGIN_CAP
463 extern login_cap_t *lc;
472 logit("Invalid user %.100s from %.100s",
473 user, get_remote_ipaddr());
474 #ifdef CUSTOM_FAILED_LOGIN
475 record_failed_login(user,
476 get_canonical_hostname(options.use_dns), "ssh");
478 #ifdef SSH_AUDIT_EVENTS
479 audit_event(SSH_INVALID_USER);
480 #endif /* SSH_AUDIT_EVENTS */
483 if (!allowed_user(pw))
485 #ifdef HAVE_LOGIN_CAP
486 if ((lc = login_getclass(pw->pw_class)) == NULL) {
487 debug("unable to get login class: %s", user);
491 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
492 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
493 debug("Approval failure for %s", user);
506 auth_debug_add(const char *fmt,...)
511 if (!auth_debug_init)
515 vsnprintf(buf, sizeof(buf), fmt, args);
517 buffer_put_cstring(&auth_debug, buf);
521 auth_debug_send(void)
525 if (!auth_debug_init)
527 while (buffer_len(&auth_debug)) {
528 msg = buffer_get_string(&auth_debug, NULL);
529 packet_send_debug("%s", msg);
535 auth_debug_reset(void)
538 buffer_clear(&auth_debug);
540 buffer_init(&auth_debug);
548 static struct passwd fake;
550 memset(&fake, 0, sizeof(fake));
551 fake.pw_name = "NOUSER";
553 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
554 fake.pw_gecos = "NOUSER";
555 fake.pw_uid = (uid_t)-1;
556 fake.pw_gid = (gid_t)-1;
557 #ifdef HAVE_PW_CLASS_IN_PASSWD
560 fake.pw_dir = "/nonexist";
561 fake.pw_shell = "/nonexist";