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 1.60 2005/06/17 02:44:32 djm Exp $");
41 #include "groupaccess.h"
45 #include "auth-options.h"
54 #include "monitor_wrap.h"
57 extern ServerOptions options;
58 extern Buffer loginmsg;
60 /* Debugging messages */
65 * Check if the user is allowed to log in via ssh. If user is listed
66 * in DenyUsers or one of user's groups is listed in DenyGroups, false
67 * will be returned. If AllowUsers isn't empty and user isn't listed
68 * there, or if AllowGroups isn't empty and one of user's groups isn't
69 * listed there, false will be returned.
70 * If the user's shell is not executable, false will be returned.
71 * Otherwise true is returned.
74 allowed_user(struct passwd * pw)
77 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
81 struct spwd *spw = NULL;
84 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
85 if (!pw || !pw->pw_name)
90 spw = getspnam(pw->pw_name);
91 #ifdef HAS_SHADOW_EXPIRE
92 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
94 #endif /* HAS_SHADOW_EXPIRE */
95 #endif /* USE_SHADOW */
97 /* grab passwd field for locked account check */
100 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
101 passwd = get_iaf_password(pw);
103 passwd = spw->sp_pwdp;
104 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
106 passwd = pw->pw_passwd;
109 /* check for locked account */
110 if (!options.use_pam && passwd && *passwd) {
113 #ifdef LOCKED_PASSWD_STRING
114 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
117 #ifdef LOCKED_PASSWD_PREFIX
118 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
119 strlen(LOCKED_PASSWD_PREFIX)) == 0)
122 #ifdef LOCKED_PASSWD_SUBSTR
123 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
126 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
128 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
130 logit("User %.100s not allowed because account is locked",
137 * Get the shell from the password data. An empty shell field is
138 * legal, and means /bin/sh.
140 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
142 /* deny if shell does not exists or is not executable */
143 if (stat(shell, &st) != 0) {
144 logit("User %.100s not allowed because shell %.100s does not exist",
148 if (S_ISREG(st.st_mode) == 0 ||
149 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
150 logit("User %.100s not allowed because shell %.100s is not executable",
155 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
156 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
157 hostname = get_canonical_hostname(options.use_dns);
158 ipaddr = get_remote_ipaddr();
161 /* Return false if user is listed in DenyUsers */
162 if (options.num_deny_users > 0) {
163 for (i = 0; i < options.num_deny_users; i++)
164 if (match_user(pw->pw_name, hostname, ipaddr,
165 options.deny_users[i])) {
166 logit("User %.100s from %.100s not allowed "
167 "because listed in DenyUsers",
168 pw->pw_name, hostname);
172 /* Return false if AllowUsers isn't empty and user isn't listed there */
173 if (options.num_allow_users > 0) {
174 for (i = 0; i < options.num_allow_users; i++)
175 if (match_user(pw->pw_name, hostname, ipaddr,
176 options.allow_users[i]))
178 /* i < options.num_allow_users iff we break for loop */
179 if (i >= options.num_allow_users) {
180 logit("User %.100s from %.100s not allowed because "
181 "not listed in AllowUsers", pw->pw_name, hostname);
185 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
186 /* Get the user's group access list (primary and supplementary) */
187 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
188 logit("User %.100s from %.100s not allowed because "
189 "not in any group", pw->pw_name, hostname);
193 /* Return false if one of user's groups is listed in DenyGroups */
194 if (options.num_deny_groups > 0)
195 if (ga_match(options.deny_groups,
196 options.num_deny_groups)) {
198 logit("User %.100s from %.100s not allowed "
199 "because a group is listed in DenyGroups",
200 pw->pw_name, hostname);
204 * Return false if AllowGroups isn't empty and one of user's groups
207 if (options.num_allow_groups > 0)
208 if (!ga_match(options.allow_groups,
209 options.num_allow_groups)) {
211 logit("User %.100s from %.100s not allowed "
212 "because none of user's groups are listed "
213 "in AllowGroups", pw->pw_name, hostname);
219 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
220 if (!sys_auth_allowed_user(pw, &loginmsg))
224 /* We found no reason not to let this user try to log on... */
229 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
231 void (*authlog) (const char *fmt,...) = verbose;
234 /* Raise logging level */
235 if (authenticated == 1 ||
237 authctxt->failures >= options.max_authtries / 2 ||
238 strcmp(method, "password") == 0)
241 if (authctxt->postponed)
242 authmsg = "Postponed";
244 authmsg = authenticated ? "Accepted" : "Failed";
246 authlog("%s %s for %s%.100s from %.200s port %d%s",
249 authctxt->valid ? "" : "invalid user ",
255 #ifdef CUSTOM_FAILED_LOGIN
256 if (authenticated == 0 && !authctxt->postponed &&
257 (strcmp(method, "password") == 0 ||
258 strncmp(method, "keyboard-interactive", 20) == 0 ||
259 strcmp(method, "challenge-response") == 0))
260 record_failed_login(authctxt->user,
261 get_canonical_hostname(options.use_dns), "ssh");
263 #ifdef SSH_AUDIT_EVENTS
264 if (authenticated == 0 && !authctxt->postponed) {
265 ssh_audit_event_t event;
267 debug3("audit failed auth attempt, method %s euid %d",
268 method, (int)geteuid());
270 * Because the auth loop is used in both monitor and slave,
271 * we must be careful to send each event only once and with
272 * enough privs to write the event.
274 event = audit_classify_auth(method);
276 case SSH_AUTH_FAIL_NONE:
277 case SSH_AUTH_FAIL_PASSWD:
278 case SSH_AUTH_FAIL_KBDINT:
282 case SSH_AUTH_FAIL_PUBKEY:
283 case SSH_AUTH_FAIL_HOSTBASED:
284 case SSH_AUTH_FAIL_GSSAPI:
286 * This is required to handle the case where privsep
287 * is enabled but it's root logging in, since
288 * use_privsep won't be cleared until after a
294 PRIVSEP(audit_event(event));
297 error("unknown authentication audit event %d", event);
304 * Check whether root logins are disallowed.
307 auth_root_allowed(char *method)
309 switch (options.permit_root_login) {
313 case PERMIT_NO_PASSWD:
314 if (strcmp(method, "password") != 0)
317 case PERMIT_FORCED_ONLY:
318 if (forced_command) {
319 logit("Root login accepted for forced command.");
324 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
330 * Given a template and a passwd structure, build a filename
331 * by substituting % tokenised options. Currently, %% becomes '%',
332 * %h becomes the home directory and %u the username.
334 * This returns a buffer allocated by xmalloc.
337 expand_authorized_keys(const char *filename, struct passwd *pw)
341 file = percent_expand(filename, "h", pw->pw_dir,
342 "u", pw->pw_name, (char *)NULL);
345 * Ensure that filename starts anchored. If not, be backward
346 * compatible and prepend the '%h/'
351 ret = xmalloc(MAXPATHLEN);
352 if (strlcpy(ret, pw->pw_dir, MAXPATHLEN) >= MAXPATHLEN ||
353 strlcat(ret, "/", MAXPATHLEN) >= MAXPATHLEN ||
354 strlcat(ret, file, MAXPATHLEN) >= MAXPATHLEN)
355 fatal("expand_authorized_keys: path too long");
362 authorized_keys_file(struct passwd *pw)
364 return expand_authorized_keys(options.authorized_keys_file, pw);
368 authorized_keys_file2(struct passwd *pw)
370 return expand_authorized_keys(options.authorized_keys_file2, pw);
373 /* return ok if key exists in sysfile or userfile */
375 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
376 const char *sysfile, const char *userfile)
381 HostStatus host_status;
383 /* Check if we know the host and its host key. */
384 found = key_new(key->type);
385 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
387 if (host_status != HOST_OK && userfile != NULL) {
388 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
389 if (options.strict_modes &&
390 (stat(user_hostfile, &st) == 0) &&
391 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
392 (st.st_mode & 022) != 0)) {
393 logit("Authentication refused for %.100s: "
394 "bad owner or modes for %.200s",
395 pw->pw_name, user_hostfile);
397 temporarily_use_uid(pw);
398 host_status = check_host_in_hostfile(user_hostfile,
399 host, key, found, NULL);
402 xfree(user_hostfile);
406 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
407 "ok" : "not found", host);
413 * Check a given file for security. This is defined as all components
414 * of the path to the file must be owned by either the owner of
415 * of the file or root and no directories must be group or world writable.
417 * XXX Should any specific check be done for sym links ?
419 * Takes an open file descriptor, the file name, a uid and and
420 * error buffer plus max size as arguments.
422 * Returns 0 on success and -1 on failure
425 secure_filename(FILE *f, const char *file, struct passwd *pw,
426 char *err, size_t errlen)
428 uid_t uid = pw->pw_uid;
429 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
434 if (realpath(file, buf) == NULL) {
435 snprintf(err, errlen, "realpath %s failed: %s", file,
439 if (realpath(pw->pw_dir, homedir) != NULL)
442 /* check the open file to avoid races */
443 if (fstat(fileno(f), &st) < 0 ||
444 (st.st_uid != 0 && st.st_uid != uid) ||
445 (st.st_mode & 022) != 0) {
446 snprintf(err, errlen, "bad ownership or modes for file %s",
451 /* for each component of the canonical path, walking upwards */
453 if ((cp = dirname(buf)) == NULL) {
454 snprintf(err, errlen, "dirname() failed");
457 strlcpy(buf, cp, sizeof(buf));
459 debug3("secure_filename: checking '%s'", buf);
460 if (stat(buf, &st) < 0 ||
461 (st.st_uid != 0 && st.st_uid != uid) ||
462 (st.st_mode & 022) != 0) {
463 snprintf(err, errlen,
464 "bad ownership or modes for directory %s", buf);
468 /* If are passed the homedir then we can stop */
469 if (comparehome && strcmp(homedir, buf) == 0) {
470 debug3("secure_filename: terminating check at '%s'",
475 * dirname should always complete with a "/" path,
476 * but we can be paranoid and check for "." too
478 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
485 getpwnamallow(const char *user)
487 #ifdef HAVE_LOGIN_CAP
488 extern login_cap_t *lc;
497 logit("Invalid user %.100s from %.100s",
498 user, get_remote_ipaddr());
499 #ifdef CUSTOM_FAILED_LOGIN
500 record_failed_login(user,
501 get_canonical_hostname(options.use_dns), "ssh");
503 #ifdef SSH_AUDIT_EVENTS
504 audit_event(SSH_INVALID_USER);
505 #endif /* SSH_AUDIT_EVENTS */
508 if (!allowed_user(pw))
510 #ifdef HAVE_LOGIN_CAP
511 if ((lc = login_getclass(pw->pw_class)) == NULL) {
512 debug("unable to get login class: %s", user);
516 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
517 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
518 debug("Approval failure for %s", user);
531 auth_debug_add(const char *fmt,...)
536 if (!auth_debug_init)
540 vsnprintf(buf, sizeof(buf), fmt, args);
542 buffer_put_cstring(&auth_debug, buf);
546 auth_debug_send(void)
550 if (!auth_debug_init)
552 while (buffer_len(&auth_debug)) {
553 msg = buffer_get_string(&auth_debug, NULL);
554 packet_send_debug("%s", msg);
560 auth_debug_reset(void)
563 buffer_clear(&auth_debug);
565 buffer_init(&auth_debug);
573 static struct passwd fake;
575 memset(&fake, 0, sizeof(fake));
576 fake.pw_name = "NOUSER";
578 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
579 fake.pw_gecos = "NOUSER";
580 fake.pw_uid = (uid_t)-1;
581 fake.pw_gid = (gid_t)-1;
582 #ifdef HAVE_PW_CLASS_IN_PASSWD
585 fake.pw_dir = "/nonexist";
586 fake.pw_shell = "/nonexist";