1 /* $OpenBSD: auth.c,v 1.74 2006/08/01 23:22:47 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>
30 #include <sys/param.h>
52 #include "groupaccess.h"
56 #include "auth-options.h"
65 #include "monitor_wrap.h"
68 extern ServerOptions options;
69 extern int use_privsep;
70 extern Buffer loginmsg;
72 /* Debugging messages */
77 * Check if the user is allowed to log in via ssh. If user is listed
78 * in DenyUsers or one of user's groups is listed in DenyGroups, false
79 * will be returned. If AllowUsers isn't empty and user isn't listed
80 * there, or if AllowGroups isn't empty and one of user's groups isn't
81 * listed there, false will be returned.
82 * If the user's shell is not executable, false will be returned.
83 * Otherwise true is returned.
86 allowed_user(struct passwd * pw)
89 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
93 struct spwd *spw = NULL;
96 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
97 if (!pw || !pw->pw_name)
101 if (!options.use_pam)
102 spw = getspnam(pw->pw_name);
103 #ifdef HAS_SHADOW_EXPIRE
104 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
106 #endif /* HAS_SHADOW_EXPIRE */
107 #endif /* USE_SHADOW */
109 /* grab passwd field for locked account check */
112 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
113 passwd = get_iaf_password(pw);
115 passwd = spw->sp_pwdp;
116 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
118 passwd = pw->pw_passwd;
121 /* check for locked account */
122 if (!options.use_pam && passwd && *passwd) {
125 #ifdef LOCKED_PASSWD_STRING
126 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
129 #ifdef LOCKED_PASSWD_PREFIX
130 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
131 strlen(LOCKED_PASSWD_PREFIX)) == 0)
134 #ifdef LOCKED_PASSWD_SUBSTR
135 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
138 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
140 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
142 logit("User %.100s not allowed because account is locked",
149 * Get the shell from the password data. An empty shell field is
150 * legal, and means /bin/sh.
152 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
154 /* deny if shell does not exists or is not executable */
155 if (stat(shell, &st) != 0) {
156 logit("User %.100s not allowed because shell %.100s does not exist",
160 if (S_ISREG(st.st_mode) == 0 ||
161 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
162 logit("User %.100s not allowed because shell %.100s is not executable",
167 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
168 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
169 hostname = get_canonical_hostname(options.use_dns);
170 ipaddr = get_remote_ipaddr();
173 /* Return false if user is listed in DenyUsers */
174 if (options.num_deny_users > 0) {
175 for (i = 0; i < options.num_deny_users; i++)
176 if (match_user(pw->pw_name, hostname, ipaddr,
177 options.deny_users[i])) {
178 logit("User %.100s from %.100s not allowed "
179 "because listed in DenyUsers",
180 pw->pw_name, hostname);
184 /* Return false if AllowUsers isn't empty and user isn't listed there */
185 if (options.num_allow_users > 0) {
186 for (i = 0; i < options.num_allow_users; i++)
187 if (match_user(pw->pw_name, hostname, ipaddr,
188 options.allow_users[i]))
190 /* i < options.num_allow_users iff we break for loop */
191 if (i >= options.num_allow_users) {
192 logit("User %.100s from %.100s not allowed because "
193 "not listed in AllowUsers", pw->pw_name, hostname);
197 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
198 /* Get the user's group access list (primary and supplementary) */
199 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
200 logit("User %.100s from %.100s not allowed because "
201 "not in any group", pw->pw_name, hostname);
205 /* Return false if one of user's groups is listed in DenyGroups */
206 if (options.num_deny_groups > 0)
207 if (ga_match(options.deny_groups,
208 options.num_deny_groups)) {
210 logit("User %.100s from %.100s not allowed "
211 "because a group is listed in DenyGroups",
212 pw->pw_name, hostname);
216 * Return false if AllowGroups isn't empty and one of user's groups
219 if (options.num_allow_groups > 0)
220 if (!ga_match(options.allow_groups,
221 options.num_allow_groups)) {
223 logit("User %.100s from %.100s not allowed "
224 "because none of user's groups are listed "
225 "in AllowGroups", pw->pw_name, hostname);
231 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
232 if (!sys_auth_allowed_user(pw, &loginmsg))
236 /* We found no reason not to let this user try to log on... */
241 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
243 void (*authlog) (const char *fmt,...) = verbose;
246 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
249 /* Raise logging level */
250 if (authenticated == 1 ||
252 authctxt->failures >= options.max_authtries / 2 ||
253 strcmp(method, "password") == 0)
256 if (authctxt->postponed)
257 authmsg = "Postponed";
259 authmsg = authenticated ? "Accepted" : "Failed";
261 authlog("%s %s for %s%.100s from %.200s port %d%s",
264 authctxt->valid ? "" : "invalid user ",
270 #ifdef CUSTOM_FAILED_LOGIN
271 if (authenticated == 0 && !authctxt->postponed &&
272 (strcmp(method, "password") == 0 ||
273 strncmp(method, "keyboard-interactive", 20) == 0 ||
274 strcmp(method, "challenge-response") == 0))
275 record_failed_login(authctxt->user,
276 get_canonical_hostname(options.use_dns), "ssh");
278 #ifdef SSH_AUDIT_EVENTS
279 if (authenticated == 0 && !authctxt->postponed)
280 audit_event(audit_classify_auth(method));
285 * Check whether root logins are disallowed.
288 auth_root_allowed(char *method)
290 switch (options.permit_root_login) {
293 case PERMIT_NO_PASSWD:
294 if (strcmp(method, "password") != 0)
297 case PERMIT_FORCED_ONLY:
298 if (forced_command) {
299 logit("Root login accepted for forced command.");
304 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
310 * Given a template and a passwd structure, build a filename
311 * by substituting % tokenised options. Currently, %% becomes '%',
312 * %h becomes the home directory and %u the username.
314 * This returns a buffer allocated by xmalloc.
317 expand_authorized_keys(const char *filename, struct passwd *pw)
319 char *file, ret[MAXPATHLEN];
322 file = percent_expand(filename, "h", pw->pw_dir,
323 "u", pw->pw_name, (char *)NULL);
326 * Ensure that filename starts anchored. If not, be backward
327 * compatible and prepend the '%h/'
332 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
333 if (i < 0 || (size_t)i >= sizeof(ret))
334 fatal("expand_authorized_keys: path too long");
336 return (xstrdup(ret));
340 authorized_keys_file(struct passwd *pw)
342 return expand_authorized_keys(options.authorized_keys_file, pw);
346 authorized_keys_file2(struct passwd *pw)
348 return expand_authorized_keys(options.authorized_keys_file2, pw);
351 /* return ok if key exists in sysfile or userfile */
353 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
354 const char *sysfile, const char *userfile)
359 HostStatus host_status;
361 /* Check if we know the host and its host key. */
362 found = key_new(key->type);
363 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
365 if (host_status != HOST_OK && userfile != NULL) {
366 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
367 if (options.strict_modes &&
368 (stat(user_hostfile, &st) == 0) &&
369 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
370 (st.st_mode & 022) != 0)) {
371 logit("Authentication refused for %.100s: "
372 "bad owner or modes for %.200s",
373 pw->pw_name, user_hostfile);
375 temporarily_use_uid(pw);
376 host_status = check_host_in_hostfile(user_hostfile,
377 host, key, found, NULL);
380 xfree(user_hostfile);
384 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
385 "ok" : "not found", host);
391 * Check a given file for security. This is defined as all components
392 * of the path to the file must be owned by either the owner of
393 * of the file or root and no directories must be group or world writable.
395 * XXX Should any specific check be done for sym links ?
397 * Takes an open file descriptor, the file name, a uid and and
398 * error buffer plus max size as arguments.
400 * Returns 0 on success and -1 on failure
403 secure_filename(FILE *f, const char *file, struct passwd *pw,
404 char *err, size_t errlen)
406 uid_t uid = pw->pw_uid;
407 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
412 if (realpath(file, buf) == NULL) {
413 snprintf(err, errlen, "realpath %s failed: %s", file,
417 if (realpath(pw->pw_dir, homedir) != NULL)
420 /* check the open file to avoid races */
421 if (fstat(fileno(f), &st) < 0 ||
422 (st.st_uid != 0 && st.st_uid != uid) ||
423 (st.st_mode & 022) != 0) {
424 snprintf(err, errlen, "bad ownership or modes for file %s",
429 /* for each component of the canonical path, walking upwards */
431 if ((cp = dirname(buf)) == NULL) {
432 snprintf(err, errlen, "dirname() failed");
435 strlcpy(buf, cp, sizeof(buf));
437 debug3("secure_filename: checking '%s'", buf);
438 if (stat(buf, &st) < 0 ||
439 (st.st_uid != 0 && st.st_uid != uid) ||
440 (st.st_mode & 022) != 0) {
441 snprintf(err, errlen,
442 "bad ownership or modes for directory %s", buf);
446 /* If are passed the homedir then we can stop */
447 if (comparehome && strcmp(homedir, buf) == 0) {
448 debug3("secure_filename: terminating check at '%s'",
453 * dirname should always complete with a "/" path,
454 * but we can be paranoid and check for "." too
456 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
463 getpwnamallow(const char *user)
465 #ifdef HAVE_LOGIN_CAP
466 extern login_cap_t *lc;
473 parse_server_match_config(&options, user,
474 get_canonical_hostname(options.use_dns), get_remote_ipaddr());
478 logit("Invalid user %.100s from %.100s",
479 user, get_remote_ipaddr());
480 #ifdef CUSTOM_FAILED_LOGIN
481 record_failed_login(user,
482 get_canonical_hostname(options.use_dns), "ssh");
484 #ifdef SSH_AUDIT_EVENTS
485 audit_event(SSH_INVALID_USER);
486 #endif /* SSH_AUDIT_EVENTS */
489 if (!allowed_user(pw))
491 #ifdef HAVE_LOGIN_CAP
492 if ((lc = login_getclass(pw->pw_class)) == NULL) {
493 debug("unable to get login class: %s", user);
497 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
498 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
499 debug("Approval failure for %s", user);
512 auth_debug_add(const char *fmt,...)
517 if (!auth_debug_init)
521 vsnprintf(buf, sizeof(buf), fmt, args);
523 buffer_put_cstring(&auth_debug, buf);
527 auth_debug_send(void)
531 if (!auth_debug_init)
533 while (buffer_len(&auth_debug)) {
534 msg = buffer_get_string(&auth_debug, NULL);
535 packet_send_debug("%s", msg);
541 auth_debug_reset(void)
544 buffer_clear(&auth_debug);
546 buffer_init(&auth_debug);
554 static struct passwd fake;
556 memset(&fake, 0, sizeof(fake));
557 fake.pw_name = "NOUSER";
559 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
560 fake.pw_gecos = "NOUSER";
561 fake.pw_uid = (uid_t)-1;
562 fake.pw_gid = (gid_t)-1;
563 #ifdef HAVE_PW_CLASS_IN_PASSWD
566 fake.pw_dir = "/nonexist";
567 fake.pw_shell = "/nonexist";