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>
32 #include <netinet/in.h>
54 #include "groupaccess.h"
61 #include "auth-options.h"
70 #include "monitor_wrap.h"
73 extern ServerOptions options;
74 extern int use_privsep;
75 extern Buffer loginmsg;
77 /* Debugging messages */
82 * Check if the user is allowed to log in via ssh. If user is listed
83 * in DenyUsers or one of user's groups is listed in DenyGroups, false
84 * will be returned. If AllowUsers isn't empty and user isn't listed
85 * there, or if AllowGroups isn't empty and one of user's groups isn't
86 * listed there, false will be returned.
87 * If the user's shell is not executable, false will be returned.
88 * Otherwise true is returned.
91 allowed_user(struct passwd * pw)
94 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
98 struct spwd *spw = NULL;
101 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
102 if (!pw || !pw->pw_name)
106 if (!options.use_pam)
107 spw = getspnam(pw->pw_name);
108 #ifdef HAS_SHADOW_EXPIRE
109 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
111 #endif /* HAS_SHADOW_EXPIRE */
112 #endif /* USE_SHADOW */
114 /* grab passwd field for locked account check */
117 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
118 passwd = get_iaf_password(pw);
120 passwd = spw->sp_pwdp;
121 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
123 passwd = pw->pw_passwd;
126 /* check for locked account */
127 if (!options.use_pam && passwd && *passwd) {
130 #ifdef LOCKED_PASSWD_STRING
131 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
134 #ifdef LOCKED_PASSWD_PREFIX
135 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
136 strlen(LOCKED_PASSWD_PREFIX)) == 0)
139 #ifdef LOCKED_PASSWD_SUBSTR
140 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
143 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
145 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
147 logit("User %.100s not allowed because account is locked",
154 * Get the shell from the password data. An empty shell field is
155 * legal, and means /bin/sh.
157 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
159 /* deny if shell does not exists or is not executable */
160 if (stat(shell, &st) != 0) {
161 logit("User %.100s not allowed because shell %.100s does not exist",
165 if (S_ISREG(st.st_mode) == 0 ||
166 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
167 logit("User %.100s not allowed because shell %.100s is not executable",
172 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
173 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
174 hostname = get_canonical_hostname(options.use_dns);
175 ipaddr = get_remote_ipaddr();
178 /* Return false if user is listed in DenyUsers */
179 if (options.num_deny_users > 0) {
180 for (i = 0; i < options.num_deny_users; i++)
181 if (match_user(pw->pw_name, hostname, ipaddr,
182 options.deny_users[i])) {
183 logit("User %.100s from %.100s not allowed "
184 "because listed in DenyUsers",
185 pw->pw_name, hostname);
189 /* Return false if AllowUsers isn't empty and user isn't listed there */
190 if (options.num_allow_users > 0) {
191 for (i = 0; i < options.num_allow_users; i++)
192 if (match_user(pw->pw_name, hostname, ipaddr,
193 options.allow_users[i]))
195 /* i < options.num_allow_users iff we break for loop */
196 if (i >= options.num_allow_users) {
197 logit("User %.100s from %.100s not allowed because "
198 "not listed in AllowUsers", pw->pw_name, hostname);
202 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
203 /* Get the user's group access list (primary and supplementary) */
204 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
205 logit("User %.100s from %.100s not allowed because "
206 "not in any group", pw->pw_name, hostname);
210 /* Return false if one of user's groups is listed in DenyGroups */
211 if (options.num_deny_groups > 0)
212 if (ga_match(options.deny_groups,
213 options.num_deny_groups)) {
215 logit("User %.100s from %.100s not allowed "
216 "because a group is listed in DenyGroups",
217 pw->pw_name, hostname);
221 * Return false if AllowGroups isn't empty and one of user's groups
224 if (options.num_allow_groups > 0)
225 if (!ga_match(options.allow_groups,
226 options.num_allow_groups)) {
228 logit("User %.100s from %.100s not allowed "
229 "because none of user's groups are listed "
230 "in AllowGroups", pw->pw_name, hostname);
236 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
237 if (!sys_auth_allowed_user(pw, &loginmsg))
241 /* We found no reason not to let this user try to log on... */
246 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
248 void (*authlog) (const char *fmt,...) = verbose;
251 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
254 /* Raise logging level */
255 if (authenticated == 1 ||
257 authctxt->failures >= options.max_authtries / 2 ||
258 strcmp(method, "password") == 0)
261 if (authctxt->postponed)
262 authmsg = "Postponed";
264 authmsg = authenticated ? "Accepted" : "Failed";
266 authlog("%s %s for %s%.100s from %.200s port %d%s",
269 authctxt->valid ? "" : "invalid user ",
275 #ifdef CUSTOM_FAILED_LOGIN
276 if (authenticated == 0 && !authctxt->postponed &&
277 (strcmp(method, "password") == 0 ||
278 strncmp(method, "keyboard-interactive", 20) == 0 ||
279 strcmp(method, "challenge-response") == 0))
280 record_failed_login(authctxt->user,
281 get_canonical_hostname(options.use_dns), "ssh");
283 #ifdef SSH_AUDIT_EVENTS
284 if (authenticated == 0 && !authctxt->postponed)
285 audit_event(audit_classify_auth(method));
290 * Check whether root logins are disallowed.
293 auth_root_allowed(char *method)
295 switch (options.permit_root_login) {
298 case PERMIT_NO_PASSWD:
299 if (strcmp(method, "password") != 0)
302 case PERMIT_FORCED_ONLY:
303 if (forced_command) {
304 logit("Root login accepted for forced command.");
309 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
315 * Given a template and a passwd structure, build a filename
316 * by substituting % tokenised options. Currently, %% becomes '%',
317 * %h becomes the home directory and %u the username.
319 * This returns a buffer allocated by xmalloc.
322 expand_authorized_keys(const char *filename, struct passwd *pw)
324 char *file, ret[MAXPATHLEN];
327 file = percent_expand(filename, "h", pw->pw_dir,
328 "u", pw->pw_name, (char *)NULL);
331 * Ensure that filename starts anchored. If not, be backward
332 * compatible and prepend the '%h/'
337 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
338 if (i < 0 || (size_t)i >= sizeof(ret))
339 fatal("expand_authorized_keys: path too long");
341 return (xstrdup(ret));
345 authorized_keys_file(struct passwd *pw)
347 return expand_authorized_keys(options.authorized_keys_file, pw);
351 authorized_keys_file2(struct passwd *pw)
353 return expand_authorized_keys(options.authorized_keys_file2, pw);
356 /* return ok if key exists in sysfile or userfile */
358 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
359 const char *sysfile, const char *userfile)
364 HostStatus host_status;
366 /* Check if we know the host and its host key. */
367 found = key_new(key->type);
368 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
370 if (host_status != HOST_OK && userfile != NULL) {
371 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
372 if (options.strict_modes &&
373 (stat(user_hostfile, &st) == 0) &&
374 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
375 (st.st_mode & 022) != 0)) {
376 logit("Authentication refused for %.100s: "
377 "bad owner or modes for %.200s",
378 pw->pw_name, user_hostfile);
380 temporarily_use_uid(pw);
381 host_status = check_host_in_hostfile(user_hostfile,
382 host, key, found, NULL);
385 xfree(user_hostfile);
389 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
390 "ok" : "not found", host);
396 * Check a given file for security. This is defined as all components
397 * of the path to the file must be owned by either the owner of
398 * of the file or root and no directories must be group or world writable.
400 * XXX Should any specific check be done for sym links ?
402 * Takes an open file descriptor, the file name, a uid and and
403 * error buffer plus max size as arguments.
405 * Returns 0 on success and -1 on failure
408 secure_filename(FILE *f, const char *file, struct passwd *pw,
409 char *err, size_t errlen)
411 uid_t uid = pw->pw_uid;
412 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
417 if (realpath(file, buf) == NULL) {
418 snprintf(err, errlen, "realpath %s failed: %s", file,
422 if (realpath(pw->pw_dir, homedir) != NULL)
425 /* check the open file to avoid races */
426 if (fstat(fileno(f), &st) < 0 ||
427 (st.st_uid != 0 && st.st_uid != uid) ||
428 (st.st_mode & 022) != 0) {
429 snprintf(err, errlen, "bad ownership or modes for file %s",
434 /* for each component of the canonical path, walking upwards */
436 if ((cp = dirname(buf)) == NULL) {
437 snprintf(err, errlen, "dirname() failed");
440 strlcpy(buf, cp, sizeof(buf));
442 debug3("secure_filename: checking '%s'", buf);
443 if (stat(buf, &st) < 0 ||
444 (st.st_uid != 0 && st.st_uid != uid) ||
445 (st.st_mode & 022) != 0) {
446 snprintf(err, errlen,
447 "bad ownership or modes for directory %s", buf);
451 /* If are passed the homedir then we can stop */
452 if (comparehome && strcmp(homedir, buf) == 0) {
453 debug3("secure_filename: terminating check at '%s'",
458 * dirname should always complete with a "/" path,
459 * but we can be paranoid and check for "." too
461 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
468 getpwnamallow(const char *user)
470 #ifdef HAVE_LOGIN_CAP
471 extern login_cap_t *lc;
478 parse_server_match_config(&options, user,
479 get_canonical_hostname(options.use_dns), get_remote_ipaddr());
483 logit("Invalid user %.100s from %.100s",
484 user, get_remote_ipaddr());
485 #ifdef CUSTOM_FAILED_LOGIN
486 record_failed_login(user,
487 get_canonical_hostname(options.use_dns), "ssh");
489 #ifdef SSH_AUDIT_EVENTS
490 audit_event(SSH_INVALID_USER);
491 #endif /* SSH_AUDIT_EVENTS */
494 if (!allowed_user(pw))
496 #ifdef HAVE_LOGIN_CAP
497 if ((lc = login_getclass(pw->pw_class)) == NULL) {
498 debug("unable to get login class: %s", user);
502 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
503 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
504 debug("Approval failure for %s", user);
517 auth_debug_add(const char *fmt,...)
522 if (!auth_debug_init)
526 vsnprintf(buf, sizeof(buf), fmt, args);
528 buffer_put_cstring(&auth_debug, buf);
532 auth_debug_send(void)
536 if (!auth_debug_init)
538 while (buffer_len(&auth_debug)) {
539 msg = buffer_get_string(&auth_debug, NULL);
540 packet_send_debug("%s", msg);
546 auth_debug_reset(void)
549 buffer_clear(&auth_debug);
551 buffer_init(&auth_debug);
559 static struct passwd fake;
561 memset(&fake, 0, sizeof(fake));
562 fake.pw_name = "NOUSER";
564 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
565 fake.pw_gecos = "NOUSER";
566 fake.pw_uid = (uid_t)-1;
567 fake.pw_gid = (gid_t)-1;
568 #ifdef HAVE_PW_CLASS_IN_PASSWD
571 fake.pw_dir = "/nonexist";
572 fake.pw_shell = "/nonexist";