1 /* $OpenBSD: auth.c,v 1.103 2013/05/19 02:42:42 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.
29 #include <sys/types.h>
31 #include <sys/param.h>
33 #include <netinet/in.h>
57 #include "groupaccess.h"
64 #include "auth-options.h"
74 #include "monitor_wrap.h"
79 extern ServerOptions options;
80 extern int use_privsep;
81 extern Buffer loginmsg;
82 extern struct passwd *privsep_pw;
84 /* Debugging messages */
89 * Check if the user is allowed to log in via ssh. If user is listed
90 * in DenyUsers or one of user's groups is listed in DenyGroups, false
91 * will be returned. If AllowUsers isn't empty and user isn't listed
92 * there, or if AllowGroups isn't empty and one of user's groups isn't
93 * listed there, false will be returned.
94 * If the user's shell is not executable, false will be returned.
95 * Otherwise true is returned.
98 allowed_user(struct passwd * pw)
101 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
104 struct spwd *spw = NULL;
107 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
108 if (!pw || !pw->pw_name)
112 if (!options.use_pam)
113 spw = getspnam(pw->pw_name);
114 #ifdef HAS_SHADOW_EXPIRE
115 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
117 #endif /* HAS_SHADOW_EXPIRE */
118 #endif /* USE_SHADOW */
120 /* grab passwd field for locked account check */
121 passwd = pw->pw_passwd;
125 passwd = get_iaf_password(pw);
127 passwd = spw->sp_pwdp;
128 #endif /* USE_LIBIAF */
131 /* check for locked account */
132 if (!options.use_pam && passwd && *passwd) {
135 #ifdef LOCKED_PASSWD_STRING
136 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
139 #ifdef LOCKED_PASSWD_PREFIX
140 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
141 strlen(LOCKED_PASSWD_PREFIX)) == 0)
144 #ifdef LOCKED_PASSWD_SUBSTR
145 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
149 free((void *) passwd);
150 #endif /* USE_LIBIAF */
152 logit("User %.100s not allowed because account is locked",
159 * Deny if shell does not exist or is not executable unless we
162 if (options.chroot_directory == NULL ||
163 strcasecmp(options.chroot_directory, "none") == 0) {
164 char *shell = xstrdup((pw->pw_shell[0] == '\0') ?
165 _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */
167 if (stat(shell, &st) != 0) {
168 logit("User %.100s not allowed because shell %.100s "
169 "does not exist", pw->pw_name, shell);
173 if (S_ISREG(st.st_mode) == 0 ||
174 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
175 logit("User %.100s not allowed because shell %.100s "
176 "is not executable", pw->pw_name, shell);
183 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
184 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
185 hostname = get_canonical_hostname(options.use_dns);
186 ipaddr = get_remote_ipaddr();
189 /* Return false if user is listed in DenyUsers */
190 if (options.num_deny_users > 0) {
191 for (i = 0; i < options.num_deny_users; i++)
192 if (match_user(pw->pw_name, hostname, ipaddr,
193 options.deny_users[i])) {
194 logit("User %.100s from %.100s not allowed "
195 "because listed in DenyUsers",
196 pw->pw_name, hostname);
200 /* Return false if AllowUsers isn't empty and user isn't listed there */
201 if (options.num_allow_users > 0) {
202 for (i = 0; i < options.num_allow_users; i++)
203 if (match_user(pw->pw_name, hostname, ipaddr,
204 options.allow_users[i]))
206 /* i < options.num_allow_users iff we break for loop */
207 if (i >= options.num_allow_users) {
208 logit("User %.100s from %.100s not allowed because "
209 "not listed in AllowUsers", pw->pw_name, hostname);
213 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
214 /* Get the user's group access list (primary and supplementary) */
215 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
216 logit("User %.100s from %.100s not allowed because "
217 "not in any group", pw->pw_name, hostname);
221 /* Return false if one of user's groups is listed in DenyGroups */
222 if (options.num_deny_groups > 0)
223 if (ga_match(options.deny_groups,
224 options.num_deny_groups)) {
226 logit("User %.100s from %.100s not allowed "
227 "because a group is listed in DenyGroups",
228 pw->pw_name, hostname);
232 * Return false if AllowGroups isn't empty and one of user's groups
235 if (options.num_allow_groups > 0)
236 if (!ga_match(options.allow_groups,
237 options.num_allow_groups)) {
239 logit("User %.100s from %.100s not allowed "
240 "because none of user's groups are listed "
241 "in AllowGroups", pw->pw_name, hostname);
247 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
248 if (!sys_auth_allowed_user(pw, &loginmsg))
252 /* We found no reason not to let this user try to log on... */
257 auth_info(Authctxt *authctxt, const char *fmt, ...)
262 free(authctxt->info);
263 authctxt->info = NULL;
266 i = vasprintf(&authctxt->info, fmt, ap);
269 if (i < 0 || authctxt->info == NULL)
270 fatal("vasprintf failed");
274 auth_log(Authctxt *authctxt, int authenticated, int partial,
275 const char *method, const char *submethod)
277 void (*authlog) (const char *fmt,...) = verbose;
280 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
283 /* Raise logging level */
284 if (authenticated == 1 ||
286 authctxt->failures >= options.max_authtries / 2 ||
287 strcmp(method, "password") == 0)
290 if (authctxt->postponed)
291 authmsg = "Postponed";
295 authmsg = authenticated ? "Accepted" : "Failed";
297 authlog("%s %s%s%s for %s%.100s from %.200s port %d %s%s%s",
300 submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod,
301 authctxt->valid ? "" : "invalid user ",
305 compat20 ? "ssh2" : "ssh1",
306 authctxt->info != NULL ? ": " : "",
307 authctxt->info != NULL ? authctxt->info : "");
308 free(authctxt->info);
309 authctxt->info = NULL;
311 #ifdef CUSTOM_FAILED_LOGIN
312 if (authenticated == 0 && !authctxt->postponed &&
313 (strcmp(method, "password") == 0 ||
314 strncmp(method, "keyboard-interactive", 20) == 0 ||
315 strcmp(method, "challenge-response") == 0))
316 record_failed_login(authctxt->user,
317 get_canonical_hostname(options.use_dns), "ssh");
318 # ifdef WITH_AIXAUTHENTICATE
320 sys_auth_record_login(authctxt->user,
321 get_canonical_hostname(options.use_dns), "ssh", &loginmsg);
324 #ifdef SSH_AUDIT_EVENTS
325 if (authenticated == 0 && !authctxt->postponed)
326 audit_event(audit_classify_auth(method));
331 * Check whether root logins are disallowed.
334 auth_root_allowed(const char *method)
336 switch (options.permit_root_login) {
339 case PERMIT_NO_PASSWD:
340 if (strcmp(method, "password") != 0)
343 case PERMIT_FORCED_ONLY:
344 if (forced_command) {
345 logit("Root login accepted for forced command.");
350 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
356 * Given a template and a passwd structure, build a filename
357 * by substituting % tokenised options. Currently, %% becomes '%',
358 * %h becomes the home directory and %u the username.
360 * This returns a buffer allocated by xmalloc.
363 expand_authorized_keys(const char *filename, struct passwd *pw)
365 char *file, ret[MAXPATHLEN];
368 file = percent_expand(filename, "h", pw->pw_dir,
369 "u", pw->pw_name, (char *)NULL);
372 * Ensure that filename starts anchored. If not, be backward
373 * compatible and prepend the '%h/'
378 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
379 if (i < 0 || (size_t)i >= sizeof(ret))
380 fatal("expand_authorized_keys: path too long");
382 return (xstrdup(ret));
386 authorized_principals_file(struct passwd *pw)
388 if (options.authorized_principals_file == NULL ||
389 strcasecmp(options.authorized_principals_file, "none") == 0)
391 return expand_authorized_keys(options.authorized_principals_file, pw);
394 /* return ok if key exists in sysfile or userfile */
396 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
397 const char *sysfile, const char *userfile)
401 HostStatus host_status;
402 struct hostkeys *hostkeys;
403 const struct hostkey_entry *found;
405 hostkeys = init_hostkeys();
406 load_hostkeys(hostkeys, host, sysfile);
407 if (userfile != NULL) {
408 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
409 if (options.strict_modes &&
410 (stat(user_hostfile, &st) == 0) &&
411 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
412 (st.st_mode & 022) != 0)) {
413 logit("Authentication refused for %.100s: "
414 "bad owner or modes for %.200s",
415 pw->pw_name, user_hostfile);
416 auth_debug_add("Ignored %.200s: bad ownership or modes",
419 temporarily_use_uid(pw);
420 load_hostkeys(hostkeys, host, user_hostfile);
425 host_status = check_key_in_hostkeys(hostkeys, key, &found);
426 if (host_status == HOST_REVOKED)
427 error("WARNING: revoked key for %s attempted authentication",
429 else if (host_status == HOST_OK)
430 debug("%s: key for %s found at %s:%ld", __func__,
431 found->host, found->file, found->line);
433 debug("%s: key for host %s not found", __func__, host);
435 free_hostkeys(hostkeys);
441 * Check a given path for security. This is defined as all components
442 * of the path to the file must be owned by either the owner of
443 * of the file or root and no directories must be group or world writable.
445 * XXX Should any specific check be done for sym links ?
447 * Takes a file name, its stat information (preferably from fstat() to
448 * avoid races), the uid of the expected owner, their home directory and an
449 * error buffer plus max size as arguments.
451 * Returns 0 on success and -1 on failure
454 auth_secure_path(const char *name, struct stat *stp, const char *pw_dir,
455 uid_t uid, char *err, size_t errlen)
457 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
462 if (realpath(name, buf) == NULL) {
463 snprintf(err, errlen, "realpath %s failed: %s", name,
467 if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL)
470 if (!S_ISREG(stp->st_mode)) {
471 snprintf(err, errlen, "%s is not a regular file", buf);
474 if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) ||
475 (stp->st_mode & 022) != 0) {
476 snprintf(err, errlen, "bad ownership or modes for file %s",
481 /* for each component of the canonical path, walking upwards */
483 if ((cp = dirname(buf)) == NULL) {
484 snprintf(err, errlen, "dirname() failed");
487 strlcpy(buf, cp, sizeof(buf));
489 if (stat(buf, &st) < 0 ||
490 (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) ||
491 (st.st_mode & 022) != 0) {
492 snprintf(err, errlen,
493 "bad ownership or modes for directory %s", buf);
497 /* If are past the homedir then we can stop */
498 if (comparehome && strcmp(homedir, buf) == 0)
502 * dirname should always complete with a "/" path,
503 * but we can be paranoid and check for "." too
505 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
512 * Version of secure_path() that accepts an open file descriptor to
515 * Returns 0 on success and -1 on failure
518 secure_filename(FILE *f, const char *file, struct passwd *pw,
519 char *err, size_t errlen)
523 /* check the open file to avoid races */
524 if (fstat(fileno(f), &st) < 0) {
525 snprintf(err, errlen, "cannot stat file %s: %s",
526 file, strerror(errno));
529 return auth_secure_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen);
533 auth_openfile(const char *file, struct passwd *pw, int strict_modes,
534 int log_missing, char *file_type)
541 if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) {
542 if (log_missing || errno != ENOENT)
543 debug("Could not open %s '%s': %s", file_type, file,
548 if (fstat(fd, &st) < 0) {
552 if (!S_ISREG(st.st_mode)) {
553 logit("User %s %s %s is not a regular file",
554 pw->pw_name, file_type, file);
559 if ((f = fdopen(fd, "r")) == NULL) {
564 secure_filename(f, file, pw, line, sizeof(line)) != 0) {
566 logit("Authentication refused: %s", line);
567 auth_debug_add("Ignored %s: %s", file_type, line);
576 auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
578 return auth_openfile(file, pw, strict_modes, 1, "authorized keys");
582 auth_openprincipals(const char *file, struct passwd *pw, int strict_modes)
584 return auth_openfile(file, pw, strict_modes, 0,
585 "authorized principals");
589 getpwnamallow(const char *user)
591 #ifdef HAVE_LOGIN_CAP
592 extern login_cap_t *lc;
598 struct connection_info *ci = get_connection_info(1, options.use_dns);
601 parse_server_match_config(&options, ci);
603 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
609 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
614 * Windows usernames are case-insensitive. To avoid later problems
615 * when trying to match the username, the user is only allowed to
616 * login if the username is given in the same case as stored in the
619 if (pw != NULL && strcmp(user, pw->pw_name) != 0) {
620 logit("Login name %.100s does not match stored username %.100s",
626 logit("Invalid user %.100s from %.100s",
627 user, get_remote_ipaddr());
628 #ifdef CUSTOM_FAILED_LOGIN
629 record_failed_login(user,
630 get_canonical_hostname(options.use_dns), "ssh");
632 #ifdef SSH_AUDIT_EVENTS
633 audit_event(SSH_INVALID_USER);
634 #endif /* SSH_AUDIT_EVENTS */
637 if (!allowed_user(pw))
639 #ifdef HAVE_LOGIN_CAP
640 if ((lc = login_getpwclass(pw)) == NULL) {
641 debug("unable to get login class: %s", user);
645 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
646 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
647 debug("Approval failure for %s", user);
659 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
661 auth_key_is_revoked(Key *key)
665 if (options.revoked_keys_file == NULL)
667 switch (ssh_krl_file_contains_key(options.revoked_keys_file, key)) {
669 return 0; /* Not revoked */
671 break; /* Not a KRL */
675 debug3("%s: treating %s as a key list", __func__,
676 options.revoked_keys_file);
677 switch (key_in_file(key, options.revoked_keys_file, 0)) {
679 /* key not revoked */
682 /* Error opening revoked_keys_file: refuse all keys */
683 error("Revoked keys file is unreadable: refusing public key "
689 key_fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
690 error("WARNING: authentication attempt with a revoked "
691 "%s key %s ", key_type(key), key_fp);
695 fatal("key_in_file returned junk");
699 auth_debug_add(const char *fmt,...)
704 if (!auth_debug_init)
708 vsnprintf(buf, sizeof(buf), fmt, args);
710 buffer_put_cstring(&auth_debug, buf);
714 auth_debug_send(void)
718 if (!auth_debug_init)
720 while (buffer_len(&auth_debug)) {
721 msg = buffer_get_string(&auth_debug, NULL);
722 packet_send_debug("%s", msg);
728 auth_debug_reset(void)
731 buffer_clear(&auth_debug);
733 buffer_init(&auth_debug);
741 static struct passwd fake;
743 memset(&fake, 0, sizeof(fake));
744 fake.pw_name = "NOUSER";
746 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
747 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
748 fake.pw_gecos = "NOUSER";
750 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
751 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
752 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS
755 fake.pw_dir = "/nonexist";
756 fake.pw_shell = "/nonexist";