1 /* $OpenBSD: auth.c,v 1.75 2006/08/03 03:34:41 deraadt 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>
52 #include "groupaccess.h"
59 #include "auth-options.h"
69 #include "monitor_wrap.h"
72 extern ServerOptions options;
73 extern int use_privsep;
74 extern Buffer loginmsg;
76 /* Debugging messages */
81 * Check if the user is allowed to log in via ssh. If user is listed
82 * in DenyUsers or one of user's groups is listed in DenyGroups, false
83 * will be returned. If AllowUsers isn't empty and user isn't listed
84 * there, or if AllowGroups isn't empty and one of user's groups isn't
85 * listed there, false will be returned.
86 * If the user's shell is not executable, false will be returned.
87 * Otherwise true is returned.
90 allowed_user(struct passwd * pw)
93 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
97 struct spwd *spw = NULL;
100 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
101 if (!pw || !pw->pw_name)
105 if (!options.use_pam)
106 spw = getspnam(pw->pw_name);
107 #ifdef HAS_SHADOW_EXPIRE
108 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
110 #endif /* HAS_SHADOW_EXPIRE */
111 #endif /* USE_SHADOW */
113 /* grab passwd field for locked account check */
116 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
117 passwd = get_iaf_password(pw);
119 passwd = spw->sp_pwdp;
120 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
122 passwd = pw->pw_passwd;
125 /* check for locked account */
126 if (!options.use_pam && passwd && *passwd) {
129 #ifdef LOCKED_PASSWD_STRING
130 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
133 #ifdef LOCKED_PASSWD_PREFIX
134 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
135 strlen(LOCKED_PASSWD_PREFIX)) == 0)
138 #ifdef LOCKED_PASSWD_SUBSTR
139 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
142 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
144 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
146 logit("User %.100s not allowed because account is locked",
153 * Get the shell from the password data. An empty shell field is
154 * legal, and means /bin/sh.
156 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
158 /* deny if shell does not exists or is not executable */
159 if (stat(shell, &st) != 0) {
160 logit("User %.100s not allowed because shell %.100s does not exist",
164 if (S_ISREG(st.st_mode) == 0 ||
165 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
166 logit("User %.100s not allowed because shell %.100s is not executable",
171 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
172 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
173 hostname = get_canonical_hostname(options.use_dns);
174 ipaddr = get_remote_ipaddr();
177 /* Return false if user is listed in DenyUsers */
178 if (options.num_deny_users > 0) {
179 for (i = 0; i < options.num_deny_users; i++)
180 if (match_user(pw->pw_name, hostname, ipaddr,
181 options.deny_users[i])) {
182 logit("User %.100s from %.100s not allowed "
183 "because listed in DenyUsers",
184 pw->pw_name, hostname);
188 /* Return false if AllowUsers isn't empty and user isn't listed there */
189 if (options.num_allow_users > 0) {
190 for (i = 0; i < options.num_allow_users; i++)
191 if (match_user(pw->pw_name, hostname, ipaddr,
192 options.allow_users[i]))
194 /* i < options.num_allow_users iff we break for loop */
195 if (i >= options.num_allow_users) {
196 logit("User %.100s from %.100s not allowed because "
197 "not listed in AllowUsers", pw->pw_name, hostname);
201 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
202 /* Get the user's group access list (primary and supplementary) */
203 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
204 logit("User %.100s from %.100s not allowed because "
205 "not in any group", pw->pw_name, hostname);
209 /* Return false if one of user's groups is listed in DenyGroups */
210 if (options.num_deny_groups > 0)
211 if (ga_match(options.deny_groups,
212 options.num_deny_groups)) {
214 logit("User %.100s from %.100s not allowed "
215 "because a group is listed in DenyGroups",
216 pw->pw_name, hostname);
220 * Return false if AllowGroups isn't empty and one of user's groups
223 if (options.num_allow_groups > 0)
224 if (!ga_match(options.allow_groups,
225 options.num_allow_groups)) {
227 logit("User %.100s from %.100s not allowed "
228 "because none of user's groups are listed "
229 "in AllowGroups", pw->pw_name, hostname);
235 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
236 if (!sys_auth_allowed_user(pw, &loginmsg))
240 /* We found no reason not to let this user try to log on... */
245 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
247 void (*authlog) (const char *fmt,...) = verbose;
250 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
253 /* Raise logging level */
254 if (authenticated == 1 ||
256 authctxt->failures >= options.max_authtries / 2 ||
257 strcmp(method, "password") == 0)
260 if (authctxt->postponed)
261 authmsg = "Postponed";
263 authmsg = authenticated ? "Accepted" : "Failed";
265 authlog("%s %s for %s%.100s from %.200s port %d%s",
268 authctxt->valid ? "" : "invalid user ",
274 #ifdef CUSTOM_FAILED_LOGIN
275 if (authenticated == 0 && !authctxt->postponed &&
276 (strcmp(method, "password") == 0 ||
277 strncmp(method, "keyboard-interactive", 20) == 0 ||
278 strcmp(method, "challenge-response") == 0))
279 record_failed_login(authctxt->user,
280 get_canonical_hostname(options.use_dns), "ssh");
282 #ifdef SSH_AUDIT_EVENTS
283 if (authenticated == 0 && !authctxt->postponed)
284 audit_event(audit_classify_auth(method));
289 * Check whether root logins are disallowed.
292 auth_root_allowed(char *method)
294 switch (options.permit_root_login) {
297 case PERMIT_NO_PASSWD:
298 if (strcmp(method, "password") != 0)
301 case PERMIT_FORCED_ONLY:
302 if (forced_command) {
303 logit("Root login accepted for forced command.");
308 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
314 * Given a template and a passwd structure, build a filename
315 * by substituting % tokenised options. Currently, %% becomes '%',
316 * %h becomes the home directory and %u the username.
318 * This returns a buffer allocated by xmalloc.
321 expand_authorized_keys(const char *filename, struct passwd *pw)
323 char *file, ret[MAXPATHLEN];
326 file = percent_expand(filename, "h", pw->pw_dir,
327 "u", pw->pw_name, (char *)NULL);
330 * Ensure that filename starts anchored. If not, be backward
331 * compatible and prepend the '%h/'
336 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
337 if (i < 0 || (size_t)i >= sizeof(ret))
338 fatal("expand_authorized_keys: path too long");
340 return (xstrdup(ret));
344 authorized_keys_file(struct passwd *pw)
346 return expand_authorized_keys(options.authorized_keys_file, pw);
350 authorized_keys_file2(struct passwd *pw)
352 return expand_authorized_keys(options.authorized_keys_file2, pw);
355 /* return ok if key exists in sysfile or userfile */
357 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
358 const char *sysfile, const char *userfile)
363 HostStatus host_status;
365 /* Check if we know the host and its host key. */
366 found = key_new(key->type);
367 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
369 if (host_status != HOST_OK && userfile != NULL) {
370 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
371 if (options.strict_modes &&
372 (stat(user_hostfile, &st) == 0) &&
373 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
374 (st.st_mode & 022) != 0)) {
375 logit("Authentication refused for %.100s: "
376 "bad owner or modes for %.200s",
377 pw->pw_name, user_hostfile);
379 temporarily_use_uid(pw);
380 host_status = check_host_in_hostfile(user_hostfile,
381 host, key, found, NULL);
384 xfree(user_hostfile);
388 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
389 "ok" : "not found", host);
395 * Check a given file for security. This is defined as all components
396 * of the path to the file must be owned by either the owner of
397 * of the file or root and no directories must be group or world writable.
399 * XXX Should any specific check be done for sym links ?
401 * Takes an open file descriptor, the file name, a uid and and
402 * error buffer plus max size as arguments.
404 * Returns 0 on success and -1 on failure
407 secure_filename(FILE *f, const char *file, struct passwd *pw,
408 char *err, size_t errlen)
410 uid_t uid = pw->pw_uid;
411 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
416 if (realpath(file, buf) == NULL) {
417 snprintf(err, errlen, "realpath %s failed: %s", file,
421 if (realpath(pw->pw_dir, homedir) != NULL)
424 /* check the open file to avoid races */
425 if (fstat(fileno(f), &st) < 0 ||
426 (st.st_uid != 0 && st.st_uid != uid) ||
427 (st.st_mode & 022) != 0) {
428 snprintf(err, errlen, "bad ownership or modes for file %s",
433 /* for each component of the canonical path, walking upwards */
435 if ((cp = dirname(buf)) == NULL) {
436 snprintf(err, errlen, "dirname() failed");
439 strlcpy(buf, cp, sizeof(buf));
441 debug3("secure_filename: checking '%s'", buf);
442 if (stat(buf, &st) < 0 ||
443 (st.st_uid != 0 && st.st_uid != uid) ||
444 (st.st_mode & 022) != 0) {
445 snprintf(err, errlen,
446 "bad ownership or modes for directory %s", buf);
450 /* If are passed the homedir then we can stop */
451 if (comparehome && strcmp(homedir, buf) == 0) {
452 debug3("secure_filename: terminating check at '%s'",
457 * dirname should always complete with a "/" path,
458 * but we can be paranoid and check for "." too
460 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
467 getpwnamallow(const char *user)
469 #ifdef HAVE_LOGIN_CAP
470 extern login_cap_t *lc;
477 parse_server_match_config(&options, user,
478 get_canonical_hostname(options.use_dns), get_remote_ipaddr());
482 logit("Invalid user %.100s from %.100s",
483 user, get_remote_ipaddr());
484 #ifdef CUSTOM_FAILED_LOGIN
485 record_failed_login(user,
486 get_canonical_hostname(options.use_dns), "ssh");
488 #ifdef SSH_AUDIT_EVENTS
489 audit_event(SSH_INVALID_USER);
490 #endif /* SSH_AUDIT_EVENTS */
493 if (!allowed_user(pw))
495 #ifdef HAVE_LOGIN_CAP
496 if ((lc = login_getclass(pw->pw_class)) == NULL) {
497 debug("unable to get login class: %s", user);
501 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
502 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
503 debug("Approval failure for %s", user);
516 auth_debug_add(const char *fmt,...)
521 if (!auth_debug_init)
525 vsnprintf(buf, sizeof(buf), fmt, args);
527 buffer_put_cstring(&auth_debug, buf);
531 auth_debug_send(void)
535 if (!auth_debug_init)
537 while (buffer_len(&auth_debug)) {
538 msg = buffer_get_string(&auth_debug, NULL);
539 packet_send_debug("%s", msg);
545 auth_debug_reset(void)
548 buffer_clear(&auth_debug);
550 buffer_init(&auth_debug);
558 static struct passwd fake;
560 memset(&fake, 0, sizeof(fake));
561 fake.pw_name = "NOUSER";
563 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
564 fake.pw_gecos = "NOUSER";
565 fake.pw_uid = (uid_t)-1;
566 fake.pw_gid = (gid_t)-1;
567 #ifdef HAVE_PW_CLASS_IN_PASSWD
570 fake.pw_dir = "/nonexist";
571 fake.pw_shell = "/nonexist";