1 /* $OpenBSD: auth.c,v 1.91 2010/11/29 23:45:51 djm 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>
56 #include "groupaccess.h"
63 #include "auth-options.h"
73 #include "monitor_wrap.h"
76 extern ServerOptions options;
77 extern int use_privsep;
78 extern Buffer loginmsg;
79 extern struct passwd *privsep_pw;
81 /* Debugging messages */
86 * Check if the user is allowed to log in via ssh. If user is listed
87 * in DenyUsers or one of user's groups is listed in DenyGroups, false
88 * will be returned. If AllowUsers isn't empty and user isn't listed
89 * there, or if AllowGroups isn't empty and one of user's groups isn't
90 * listed there, false will be returned.
91 * If the user's shell is not executable, false will be returned.
92 * Otherwise true is returned.
95 allowed_user(struct passwd * pw)
98 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
101 struct spwd *spw = NULL;
104 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
105 if (!pw || !pw->pw_name)
109 if (!options.use_pam)
110 spw = getspnam(pw->pw_name);
111 #ifdef HAS_SHADOW_EXPIRE
112 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
114 #endif /* HAS_SHADOW_EXPIRE */
115 #endif /* USE_SHADOW */
117 /* grab passwd field for locked account check */
118 passwd = pw->pw_passwd;
122 passwd = get_iaf_password(pw);
124 passwd = spw->sp_pwdp;
125 #endif /* USE_LIBIAF */
128 /* check for locked account */
129 if (!options.use_pam && passwd && *passwd) {
132 #ifdef LOCKED_PASSWD_STRING
133 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
136 #ifdef LOCKED_PASSWD_PREFIX
137 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
138 strlen(LOCKED_PASSWD_PREFIX)) == 0)
141 #ifdef LOCKED_PASSWD_SUBSTR
142 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
146 free((void *) passwd);
147 #endif /* USE_LIBIAF */
149 logit("User %.100s not allowed because account is locked",
156 * Deny if shell does not exist or is not executable unless we
159 if (options.chroot_directory == NULL ||
160 strcasecmp(options.chroot_directory, "none") == 0) {
161 char *shell = xstrdup((pw->pw_shell[0] == '\0') ?
162 _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */
164 if (stat(shell, &st) != 0) {
165 logit("User %.100s not allowed because shell %.100s "
166 "does not exist", pw->pw_name, shell);
170 if (S_ISREG(st.st_mode) == 0 ||
171 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
172 logit("User %.100s not allowed because shell %.100s "
173 "is not executable", pw->pw_name, shell);
180 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
181 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
182 hostname = get_canonical_hostname(options.use_dns);
183 ipaddr = get_remote_ipaddr();
186 /* Return false if user is listed in DenyUsers */
187 if (options.num_deny_users > 0) {
188 for (i = 0; i < options.num_deny_users; i++)
189 if (match_user(pw->pw_name, hostname, ipaddr,
190 options.deny_users[i])) {
191 logit("User %.100s from %.100s not allowed "
192 "because listed in DenyUsers",
193 pw->pw_name, hostname);
197 /* Return false if AllowUsers isn't empty and user isn't listed there */
198 if (options.num_allow_users > 0) {
199 for (i = 0; i < options.num_allow_users; i++)
200 if (match_user(pw->pw_name, hostname, ipaddr,
201 options.allow_users[i]))
203 /* i < options.num_allow_users iff we break for loop */
204 if (i >= options.num_allow_users) {
205 logit("User %.100s from %.100s not allowed because "
206 "not listed in AllowUsers", pw->pw_name, hostname);
210 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
211 /* Get the user's group access list (primary and supplementary) */
212 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
213 logit("User %.100s from %.100s not allowed because "
214 "not in any group", pw->pw_name, hostname);
218 /* Return false if one of user's groups is listed in DenyGroups */
219 if (options.num_deny_groups > 0)
220 if (ga_match(options.deny_groups,
221 options.num_deny_groups)) {
223 logit("User %.100s from %.100s not allowed "
224 "because a group is listed in DenyGroups",
225 pw->pw_name, hostname);
229 * Return false if AllowGroups isn't empty and one of user's groups
232 if (options.num_allow_groups > 0)
233 if (!ga_match(options.allow_groups,
234 options.num_allow_groups)) {
236 logit("User %.100s from %.100s not allowed "
237 "because none of user's groups are listed "
238 "in AllowGroups", pw->pw_name, hostname);
244 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
245 if (!sys_auth_allowed_user(pw, &loginmsg))
249 /* We found no reason not to let this user try to log on... */
254 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
256 void (*authlog) (const char *fmt,...) = verbose;
259 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
262 /* Raise logging level */
263 if (authenticated == 1 ||
265 authctxt->failures >= options.max_authtries / 2 ||
266 strcmp(method, "password") == 0)
269 if (authctxt->postponed)
270 authmsg = "Postponed";
272 authmsg = authenticated ? "Accepted" : "Failed";
274 authlog("%s %s for %s%.100s from %.200s port %d%s",
277 authctxt->valid ? "" : "invalid user ",
278 (authctxt->user && authctxt->user[0]) ?
279 authctxt->user : "unknown",
284 #ifdef CUSTOM_FAILED_LOGIN
285 if (authenticated == 0 && !authctxt->postponed &&
286 (strcmp(method, "password") == 0 ||
287 strncmp(method, "keyboard-interactive", 20) == 0 ||
288 strcmp(method, "challenge-response") == 0))
289 record_failed_login(authctxt->user,
290 get_canonical_hostname(options.use_dns), "ssh");
291 # ifdef WITH_AIXAUTHENTICATE
293 sys_auth_record_login(authctxt->user,
294 get_canonical_hostname(options.use_dns), "ssh", &loginmsg);
297 #ifdef SSH_AUDIT_EVENTS
298 if (authenticated == 0 && !authctxt->postponed)
299 audit_event(audit_classify_auth(method));
304 * Check whether root logins are disallowed.
307 auth_root_allowed(char *method)
309 switch (options.permit_root_login) {
312 case PERMIT_NO_PASSWD:
313 if (strcmp(method, "password") != 0)
316 case PERMIT_FORCED_ONLY:
317 if (forced_command) {
318 logit("Root login accepted for forced command.");
323 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
329 * Given a template and a passwd structure, build a filename
330 * by substituting % tokenised options. Currently, %% becomes '%',
331 * %h becomes the home directory and %u the username.
333 * This returns a buffer allocated by xmalloc.
336 expand_authorized_keys(const char *filename, struct passwd *pw)
338 char *file, ret[MAXPATHLEN];
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 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
352 if (i < 0 || (size_t)i >= sizeof(ret))
353 fatal("expand_authorized_keys: path too long");
355 return (xstrdup(ret));
359 authorized_keys_file(struct passwd *pw)
361 return expand_authorized_keys(options.authorized_keys_file, pw);
365 authorized_keys_file2(struct passwd *pw)
367 return expand_authorized_keys(options.authorized_keys_file2, pw);
371 authorized_principals_file(struct passwd *pw)
373 if (options.authorized_principals_file == NULL)
375 return expand_authorized_keys(options.authorized_principals_file, pw);
378 /* return ok if key exists in sysfile or userfile */
380 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
381 const char *sysfile, const char *userfile)
385 HostStatus host_status;
386 struct hostkeys *hostkeys;
387 const struct hostkey_entry *found;
389 hostkeys = init_hostkeys();
390 load_hostkeys(hostkeys, host, sysfile);
391 if (userfile != NULL) {
392 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
393 if (options.strict_modes &&
394 (stat(user_hostfile, &st) == 0) &&
395 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
396 (st.st_mode & 022) != 0)) {
397 logit("Authentication refused for %.100s: "
398 "bad owner or modes for %.200s",
399 pw->pw_name, user_hostfile);
400 auth_debug_add("Ignored %.200s: bad ownership or modes",
403 temporarily_use_uid(pw);
404 load_hostkeys(hostkeys, host, user_hostfile);
407 xfree(user_hostfile);
409 host_status = check_key_in_hostkeys(hostkeys, key, &found);
410 if (host_status == HOST_REVOKED)
411 error("WARNING: revoked key for %s attempted authentication",
413 else if (host_status == HOST_OK)
414 debug("%s: key for %s found at %s:%ld", __func__,
415 found->host, found->file, found->line);
417 debug("%s: key for host %s not found", __func__, host);
419 free_hostkeys(hostkeys);
426 * Check a given file for security. This is defined as all components
427 * of the path to the file must be owned by either the owner of
428 * of the file or root and no directories must be group or world writable.
430 * XXX Should any specific check be done for sym links ?
432 * Takes an open file descriptor, the file name, a uid and and
433 * error buffer plus max size as arguments.
435 * Returns 0 on success and -1 on failure
438 secure_filename(FILE *f, const char *file, struct passwd *pw,
439 char *err, size_t errlen)
441 uid_t uid = pw->pw_uid;
442 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
447 if (realpath(file, buf) == NULL) {
448 snprintf(err, errlen, "realpath %s failed: %s", file,
452 if (realpath(pw->pw_dir, homedir) != NULL)
455 /* check the open file to avoid races */
456 if (fstat(fileno(f), &st) < 0 ||
457 (st.st_uid != 0 && st.st_uid != uid) ||
458 (st.st_mode & 022) != 0) {
459 snprintf(err, errlen, "bad ownership or modes for file %s",
464 /* for each component of the canonical path, walking upwards */
466 if ((cp = dirname(buf)) == NULL) {
467 snprintf(err, errlen, "dirname() failed");
470 strlcpy(buf, cp, sizeof(buf));
472 debug3("secure_filename: checking '%s'", buf);
473 if (stat(buf, &st) < 0 ||
474 (st.st_uid != 0 && st.st_uid != uid) ||
475 (st.st_mode & 022) != 0) {
476 snprintf(err, errlen,
477 "bad ownership or modes for directory %s", buf);
481 /* If are past the homedir then we can stop */
482 if (comparehome && strcmp(homedir, buf) == 0) {
483 debug3("secure_filename: terminating check at '%s'",
488 * dirname should always complete with a "/" path,
489 * but we can be paranoid and check for "." too
491 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
498 auth_openfile(const char *file, struct passwd *pw, int strict_modes,
499 int log_missing, char *file_type)
506 if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) {
507 if (log_missing || errno != ENOENT)
508 debug("Could not open %s '%s': %s", file_type, file,
513 if (fstat(fd, &st) < 0) {
517 if (!S_ISREG(st.st_mode)) {
518 logit("User %s %s %s is not a regular file",
519 pw->pw_name, file_type, file);
524 if ((f = fdopen(fd, "r")) == NULL) {
529 secure_filename(f, file, pw, line, sizeof(line)) != 0) {
531 logit("Authentication refused: %s", line);
532 auth_debug_add("Ignored %s: %s", file_type, line);
541 auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
543 return auth_openfile(file, pw, strict_modes, 1, "authorized keys");
547 auth_openprincipals(const char *file, struct passwd *pw, int strict_modes)
549 return auth_openfile(file, pw, strict_modes, 0,
550 "authorized principals");
554 getpwnamallow(const char *user)
556 #ifdef HAVE_LOGIN_CAP
557 extern login_cap_t *lc;
564 parse_server_match_config(&options, user,
565 get_canonical_hostname(options.use_dns), get_remote_ipaddr());
567 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
573 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
578 * Windows usernames are case-insensitive. To avoid later problems
579 * when trying to match the username, the user is only allowed to
580 * login if the username is given in the same case as stored in the
583 if (pw != NULL && strcmp(user, pw->pw_name) != 0) {
584 logit("Login name %.100s does not match stored username %.100s",
590 logit("Invalid user %.100s from %.100s",
591 (user && user[0]) ? user : "unknown",
592 get_remote_ipaddr());
593 #ifdef CUSTOM_FAILED_LOGIN
594 record_failed_login(user,
595 get_canonical_hostname(options.use_dns), "ssh");
597 #ifdef SSH_AUDIT_EVENTS
598 audit_event(SSH_INVALID_USER);
599 #endif /* SSH_AUDIT_EVENTS */
602 if (!allowed_user(pw))
604 #ifdef HAVE_LOGIN_CAP
605 if ((lc = login_getclass(pw->pw_class)) == NULL) {
606 debug("unable to get login class: %s", user);
610 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
611 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
612 debug("Approval failure for %s", user);
624 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
626 auth_key_is_revoked(Key *key)
630 if (options.revoked_keys_file == NULL)
633 switch (key_in_file(key, options.revoked_keys_file, 0)) {
635 /* key not revoked */
638 /* Error opening revoked_keys_file: refuse all keys */
639 error("Revoked keys file is unreadable: refusing public key "
644 key_fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
645 error("WARNING: authentication attempt with a revoked "
646 "%s key %s ", key_type(key), key_fp);
650 fatal("key_in_file returned junk");
654 auth_debug_add(const char *fmt,...)
659 if (!auth_debug_init)
663 vsnprintf(buf, sizeof(buf), fmt, args);
665 buffer_put_cstring(&auth_debug, buf);
669 auth_debug_send(void)
673 if (!auth_debug_init)
675 while (buffer_len(&auth_debug)) {
676 msg = buffer_get_string(&auth_debug, NULL);
677 packet_send_debug("%s", msg);
683 auth_debug_reset(void)
686 buffer_clear(&auth_debug);
688 buffer_init(&auth_debug);
696 static struct passwd fake;
698 memset(&fake, 0, sizeof(fake));
699 fake.pw_name = "NOUSER";
701 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
702 fake.pw_gecos = "NOUSER";
703 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
704 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
705 #ifdef HAVE_PW_CLASS_IN_PASSWD
708 fake.pw_dir = "/nonexist";
709 fake.pw_shell = "/nonexist";