1 /* $OpenBSD: auth.c,v 1.106 2014/07/15 15:54:14 millert 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"
64 #include "auth-options.h"
73 #include "monitor_wrap.h"
78 extern ServerOptions options;
79 extern int use_privsep;
80 extern Buffer loginmsg;
81 extern struct passwd *privsep_pw;
83 /* Debugging messages */
88 * Check if the user is allowed to log in via ssh. If user is listed
89 * in DenyUsers or one of user's groups is listed in DenyGroups, false
90 * will be returned. If AllowUsers isn't empty and user isn't listed
91 * there, or if AllowGroups isn't empty and one of user's groups isn't
92 * listed there, false will be returned.
93 * If the user's shell is not executable, false will be returned.
94 * Otherwise true is returned.
97 allowed_user(struct passwd * pw)
100 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
103 struct spwd *spw = NULL;
106 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
107 if (!pw || !pw->pw_name)
111 if (!options.use_pam)
112 spw = getspnam(pw->pw_name);
113 #ifdef HAS_SHADOW_EXPIRE
114 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
116 #endif /* HAS_SHADOW_EXPIRE */
117 #endif /* USE_SHADOW */
119 /* grab passwd field for locked account check */
120 passwd = pw->pw_passwd;
124 passwd = get_iaf_password(pw);
126 passwd = spw->sp_pwdp;
127 #endif /* USE_LIBIAF */
130 /* check for locked account */
131 if (!options.use_pam && passwd && *passwd) {
134 #ifdef LOCKED_PASSWD_STRING
135 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
138 #ifdef LOCKED_PASSWD_PREFIX
139 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
140 strlen(LOCKED_PASSWD_PREFIX)) == 0)
143 #ifdef LOCKED_PASSWD_SUBSTR
144 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
148 free((void *) passwd);
149 #endif /* USE_LIBIAF */
151 logit("User %.100s not allowed because account is locked",
158 * Deny if shell does not exist or is not executable unless we
161 if (options.chroot_directory == NULL ||
162 strcasecmp(options.chroot_directory, "none") == 0) {
163 char *shell = xstrdup((pw->pw_shell[0] == '\0') ?
164 _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */
166 if (stat(shell, &st) != 0) {
167 logit("User %.100s not allowed because shell %.100s "
168 "does not exist", pw->pw_name, shell);
172 if (S_ISREG(st.st_mode) == 0 ||
173 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
174 logit("User %.100s not allowed because shell %.100s "
175 "is not executable", pw->pw_name, shell);
182 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
183 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
184 hostname = get_canonical_hostname(options.use_dns);
185 ipaddr = get_remote_ipaddr();
188 /* Return false if user is listed in DenyUsers */
189 if (options.num_deny_users > 0) {
190 for (i = 0; i < options.num_deny_users; i++)
191 if (match_user(pw->pw_name, hostname, ipaddr,
192 options.deny_users[i])) {
193 logit("User %.100s from %.100s not allowed "
194 "because listed in DenyUsers",
195 pw->pw_name, hostname);
199 /* Return false if AllowUsers isn't empty and user isn't listed there */
200 if (options.num_allow_users > 0) {
201 for (i = 0; i < options.num_allow_users; i++)
202 if (match_user(pw->pw_name, hostname, ipaddr,
203 options.allow_users[i]))
205 /* i < options.num_allow_users iff we break for loop */
206 if (i >= options.num_allow_users) {
207 logit("User %.100s from %.100s not allowed because "
208 "not listed in AllowUsers", pw->pw_name, hostname);
212 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
213 /* Get the user's group access list (primary and supplementary) */
214 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
215 logit("User %.100s from %.100s not allowed because "
216 "not in any group", pw->pw_name, hostname);
220 /* Return false if one of user's groups is listed in DenyGroups */
221 if (options.num_deny_groups > 0)
222 if (ga_match(options.deny_groups,
223 options.num_deny_groups)) {
225 logit("User %.100s from %.100s not allowed "
226 "because a group is listed in DenyGroups",
227 pw->pw_name, hostname);
231 * Return false if AllowGroups isn't empty and one of user's groups
234 if (options.num_allow_groups > 0)
235 if (!ga_match(options.allow_groups,
236 options.num_allow_groups)) {
238 logit("User %.100s from %.100s not allowed "
239 "because none of user's groups are listed "
240 "in AllowGroups", pw->pw_name, hostname);
246 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
247 if (!sys_auth_allowed_user(pw, &loginmsg))
251 /* We found no reason not to let this user try to log on... */
256 auth_info(Authctxt *authctxt, const char *fmt, ...)
261 free(authctxt->info);
262 authctxt->info = NULL;
265 i = vasprintf(&authctxt->info, fmt, ap);
268 if (i < 0 || authctxt->info == NULL)
269 fatal("vasprintf failed");
273 auth_log(Authctxt *authctxt, int authenticated, int partial,
274 const char *method, const char *submethod)
276 void (*authlog) (const char *fmt,...) = verbose;
279 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
282 /* Raise logging level */
283 if (authenticated == 1 ||
285 authctxt->failures >= options.max_authtries / 2 ||
286 strcmp(method, "password") == 0)
289 if (authctxt->postponed)
290 authmsg = "Postponed";
294 authmsg = authenticated ? "Accepted" : "Failed";
296 authlog("%s %s%s%s for %s%.100s from %.200s port %d %s%s%s",
299 submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod,
300 authctxt->valid ? "" : "invalid user ",
304 compat20 ? "ssh2" : "ssh1",
305 authctxt->info != NULL ? ": " : "",
306 authctxt->info != NULL ? authctxt->info : "");
307 free(authctxt->info);
308 authctxt->info = NULL;
310 #ifdef CUSTOM_FAILED_LOGIN
311 if (authenticated == 0 && !authctxt->postponed &&
312 (strcmp(method, "password") == 0 ||
313 strncmp(method, "keyboard-interactive", 20) == 0 ||
314 strcmp(method, "challenge-response") == 0))
315 record_failed_login(authctxt->user,
316 get_canonical_hostname(options.use_dns), "ssh");
317 # ifdef WITH_AIXAUTHENTICATE
319 sys_auth_record_login(authctxt->user,
320 get_canonical_hostname(options.use_dns), "ssh", &loginmsg);
323 #ifdef SSH_AUDIT_EVENTS
324 if (authenticated == 0 && !authctxt->postponed)
325 audit_event(audit_classify_auth(method));
331 auth_maxtries_exceeded(Authctxt *authctxt)
333 packet_disconnect("Too many authentication failures for "
334 "%s%.100s from %.200s port %d %s",
335 authctxt->valid ? "" : "invalid user ",
339 compat20 ? "ssh2" : "ssh1");
344 * Check whether root logins are disallowed.
347 auth_root_allowed(const char *method)
349 switch (options.permit_root_login) {
352 case PERMIT_NO_PASSWD:
353 if (strcmp(method, "password") != 0)
356 case PERMIT_FORCED_ONLY:
357 if (forced_command) {
358 logit("Root login accepted for forced command.");
363 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
369 * Given a template and a passwd structure, build a filename
370 * by substituting % tokenised options. Currently, %% becomes '%',
371 * %h becomes the home directory and %u the username.
373 * This returns a buffer allocated by xmalloc.
376 expand_authorized_keys(const char *filename, struct passwd *pw)
378 char *file, ret[MAXPATHLEN];
381 file = percent_expand(filename, "h", pw->pw_dir,
382 "u", pw->pw_name, (char *)NULL);
385 * Ensure that filename starts anchored. If not, be backward
386 * compatible and prepend the '%h/'
391 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
392 if (i < 0 || (size_t)i >= sizeof(ret))
393 fatal("expand_authorized_keys: path too long");
395 return (xstrdup(ret));
399 authorized_principals_file(struct passwd *pw)
401 if (options.authorized_principals_file == NULL ||
402 strcasecmp(options.authorized_principals_file, "none") == 0)
404 return expand_authorized_keys(options.authorized_principals_file, pw);
407 /* return ok if key exists in sysfile or userfile */
409 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
410 const char *sysfile, const char *userfile)
414 HostStatus host_status;
415 struct hostkeys *hostkeys;
416 const struct hostkey_entry *found;
418 hostkeys = init_hostkeys();
419 load_hostkeys(hostkeys, host, sysfile);
420 if (userfile != NULL) {
421 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
422 if (options.strict_modes &&
423 (stat(user_hostfile, &st) == 0) &&
424 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
425 (st.st_mode & 022) != 0)) {
426 logit("Authentication refused for %.100s: "
427 "bad owner or modes for %.200s",
428 pw->pw_name, user_hostfile);
429 auth_debug_add("Ignored %.200s: bad ownership or modes",
432 temporarily_use_uid(pw);
433 load_hostkeys(hostkeys, host, user_hostfile);
438 host_status = check_key_in_hostkeys(hostkeys, key, &found);
439 if (host_status == HOST_REVOKED)
440 error("WARNING: revoked key for %s attempted authentication",
442 else if (host_status == HOST_OK)
443 debug("%s: key for %s found at %s:%ld", __func__,
444 found->host, found->file, found->line);
446 debug("%s: key for host %s not found", __func__, host);
448 free_hostkeys(hostkeys);
454 * Check a given path for security. This is defined as all components
455 * of the path to the file must be owned by either the owner of
456 * of the file or root and no directories must be group or world writable.
458 * XXX Should any specific check be done for sym links ?
460 * Takes a file name, its stat information (preferably from fstat() to
461 * avoid races), the uid of the expected owner, their home directory and an
462 * error buffer plus max size as arguments.
464 * Returns 0 on success and -1 on failure
467 auth_secure_path(const char *name, struct stat *stp, const char *pw_dir,
468 uid_t uid, char *err, size_t errlen)
470 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
475 if (realpath(name, buf) == NULL) {
476 snprintf(err, errlen, "realpath %s failed: %s", name,
480 if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL)
483 if (!S_ISREG(stp->st_mode)) {
484 snprintf(err, errlen, "%s is not a regular file", buf);
487 if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) ||
488 (stp->st_mode & 022) != 0) {
489 snprintf(err, errlen, "bad ownership or modes for file %s",
494 /* for each component of the canonical path, walking upwards */
496 if ((cp = dirname(buf)) == NULL) {
497 snprintf(err, errlen, "dirname() failed");
500 strlcpy(buf, cp, sizeof(buf));
502 if (stat(buf, &st) < 0 ||
503 (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) ||
504 (st.st_mode & 022) != 0) {
505 snprintf(err, errlen,
506 "bad ownership or modes for directory %s", buf);
510 /* If are past the homedir then we can stop */
511 if (comparehome && strcmp(homedir, buf) == 0)
515 * dirname should always complete with a "/" path,
516 * but we can be paranoid and check for "." too
518 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
525 * Version of secure_path() that accepts an open file descriptor to
528 * Returns 0 on success and -1 on failure
531 secure_filename(FILE *f, const char *file, struct passwd *pw,
532 char *err, size_t errlen)
536 /* check the open file to avoid races */
537 if (fstat(fileno(f), &st) < 0) {
538 snprintf(err, errlen, "cannot stat file %s: %s",
539 file, strerror(errno));
542 return auth_secure_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen);
546 auth_openfile(const char *file, struct passwd *pw, int strict_modes,
547 int log_missing, char *file_type)
554 if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) {
555 if (log_missing || errno != ENOENT)
556 debug("Could not open %s '%s': %s", file_type, file,
561 if (fstat(fd, &st) < 0) {
565 if (!S_ISREG(st.st_mode)) {
566 logit("User %s %s %s is not a regular file",
567 pw->pw_name, file_type, file);
572 if ((f = fdopen(fd, "r")) == NULL) {
577 secure_filename(f, file, pw, line, sizeof(line)) != 0) {
579 logit("Authentication refused: %s", line);
580 auth_debug_add("Ignored %s: %s", file_type, line);
589 auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
591 return auth_openfile(file, pw, strict_modes, 1, "authorized keys");
595 auth_openprincipals(const char *file, struct passwd *pw, int strict_modes)
597 return auth_openfile(file, pw, strict_modes, 0,
598 "authorized principals");
602 getpwnamallow(const char *user)
604 #ifdef HAVE_LOGIN_CAP
605 extern login_cap_t *lc;
611 struct connection_info *ci = get_connection_info(1, options.use_dns);
614 parse_server_match_config(&options, ci);
616 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
622 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
627 * Windows usernames are case-insensitive. To avoid later problems
628 * when trying to match the username, the user is only allowed to
629 * login if the username is given in the same case as stored in the
632 if (pw != NULL && strcmp(user, pw->pw_name) != 0) {
633 logit("Login name %.100s does not match stored username %.100s",
639 logit("Invalid user %.100s from %.100s",
640 user, get_remote_ipaddr());
641 #ifdef CUSTOM_FAILED_LOGIN
642 record_failed_login(user,
643 get_canonical_hostname(options.use_dns), "ssh");
645 #ifdef SSH_AUDIT_EVENTS
646 audit_event(SSH_INVALID_USER);
647 #endif /* SSH_AUDIT_EVENTS */
650 if (!allowed_user(pw))
652 #ifdef HAVE_LOGIN_CAP
653 if ((lc = login_getclass(pw->pw_class)) == NULL) {
654 debug("unable to get login class: %s", user);
658 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
659 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
660 debug("Approval failure for %s", user);
672 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
674 auth_key_is_revoked(Key *key)
679 if (options.revoked_keys_file == NULL)
681 switch (ssh_krl_file_contains_key(options.revoked_keys_file, key)) {
683 return 0; /* Not revoked */
685 break; /* Not a KRL */
690 debug3("%s: treating %s as a key list", __func__,
691 options.revoked_keys_file);
692 switch (key_in_file(key, options.revoked_keys_file, 0)) {
694 /* key not revoked */
697 /* Error opening revoked_keys_file: refuse all keys */
698 error("Revoked keys file is unreadable: refusing public key "
705 key_fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
706 error("WARNING: authentication attempt with a revoked "
707 "%s key %s ", key_type(key), key_fp);
712 fatal("key_in_file returned junk");
716 auth_debug_add(const char *fmt,...)
721 if (!auth_debug_init)
725 vsnprintf(buf, sizeof(buf), fmt, args);
727 buffer_put_cstring(&auth_debug, buf);
731 auth_debug_send(void)
735 if (!auth_debug_init)
737 while (buffer_len(&auth_debug)) {
738 msg = buffer_get_string(&auth_debug, NULL);
739 packet_send_debug("%s", msg);
745 auth_debug_reset(void)
748 buffer_clear(&auth_debug);
750 buffer_init(&auth_debug);
758 static struct passwd fake;
760 memset(&fake, 0, sizeof(fake));
761 fake.pw_name = "NOUSER";
763 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
764 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
765 fake.pw_gecos = "NOUSER";
767 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
768 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
769 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS
772 fake.pw_dir = "/nonexist";
773 fake.pw_shell = "/nonexist";