1 /* $OpenBSD: auth.c,v 1.113 2015/08/21 03:42:19 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>
32 #include <netinet/in.h>
57 #include "groupaccess.h"
65 #include "auth-options.h"
74 #include "monitor_wrap.h"
80 extern ServerOptions options;
81 extern int use_privsep;
82 extern Buffer loginmsg;
83 extern struct passwd *privsep_pw;
85 /* Debugging messages */
90 * Check if the user is allowed to log in via ssh. If user is listed
91 * in DenyUsers or one of user's groups is listed in DenyGroups, false
92 * will be returned. If AllowUsers isn't empty and user isn't listed
93 * there, or if AllowGroups isn't empty and one of user's groups isn't
94 * listed there, false will be returned.
95 * If the user's shell is not executable, false will be returned.
96 * Otherwise true is returned.
99 allowed_user(struct passwd * pw)
102 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
105 struct spwd *spw = NULL;
108 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
109 if (!pw || !pw->pw_name)
113 if (!options.use_pam)
114 spw = getspnam(pw->pw_name);
115 #ifdef HAS_SHADOW_EXPIRE
116 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
118 #endif /* HAS_SHADOW_EXPIRE */
119 #endif /* USE_SHADOW */
121 /* grab passwd field for locked account check */
122 passwd = pw->pw_passwd;
126 passwd = get_iaf_password(pw);
128 passwd = spw->sp_pwdp;
129 #endif /* USE_LIBIAF */
132 /* check for locked account */
133 if (!options.use_pam && passwd && *passwd) {
136 #ifdef LOCKED_PASSWD_STRING
137 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
140 #ifdef LOCKED_PASSWD_PREFIX
141 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
142 strlen(LOCKED_PASSWD_PREFIX)) == 0)
145 #ifdef LOCKED_PASSWD_SUBSTR
146 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
150 free((void *) passwd);
151 #endif /* USE_LIBIAF */
153 logit("User %.100s not allowed because account is locked",
160 * Deny if shell does not exist or is not executable unless we
163 if (options.chroot_directory == NULL ||
164 strcasecmp(options.chroot_directory, "none") == 0) {
165 char *shell = xstrdup((pw->pw_shell[0] == '\0') ?
166 _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */
168 if (stat(shell, &st) != 0) {
169 logit("User %.100s not allowed because shell %.100s "
170 "does not exist", pw->pw_name, shell);
174 if (S_ISREG(st.st_mode) == 0 ||
175 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
176 logit("User %.100s not allowed because shell %.100s "
177 "is not executable", pw->pw_name, shell);
184 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
185 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
186 hostname = get_canonical_hostname(options.use_dns);
187 ipaddr = get_remote_ipaddr();
190 /* Return false if user is listed in DenyUsers */
191 if (options.num_deny_users > 0) {
192 for (i = 0; i < options.num_deny_users; i++)
193 if (match_user(pw->pw_name, hostname, ipaddr,
194 options.deny_users[i])) {
195 logit("User %.100s from %.100s not allowed "
196 "because listed in DenyUsers",
197 pw->pw_name, hostname);
201 /* Return false if AllowUsers isn't empty and user isn't listed there */
202 if (options.num_allow_users > 0) {
203 for (i = 0; i < options.num_allow_users; i++)
204 if (match_user(pw->pw_name, hostname, ipaddr,
205 options.allow_users[i]))
207 /* i < options.num_allow_users iff we break for loop */
208 if (i >= options.num_allow_users) {
209 logit("User %.100s from %.100s not allowed because "
210 "not listed in AllowUsers", pw->pw_name, hostname);
214 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
215 /* Get the user's group access list (primary and supplementary) */
216 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
217 logit("User %.100s from %.100s not allowed because "
218 "not in any group", pw->pw_name, hostname);
222 /* Return false if one of user's groups is listed in DenyGroups */
223 if (options.num_deny_groups > 0)
224 if (ga_match(options.deny_groups,
225 options.num_deny_groups)) {
227 logit("User %.100s from %.100s not allowed "
228 "because a group is listed in DenyGroups",
229 pw->pw_name, hostname);
233 * Return false if AllowGroups isn't empty and one of user's groups
236 if (options.num_allow_groups > 0)
237 if (!ga_match(options.allow_groups,
238 options.num_allow_groups)) {
240 logit("User %.100s from %.100s not allowed "
241 "because none of user's groups are listed "
242 "in AllowGroups", pw->pw_name, hostname);
248 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
249 if (!sys_auth_allowed_user(pw, &loginmsg))
253 /* We found no reason not to let this user try to log on... */
258 auth_info(Authctxt *authctxt, const char *fmt, ...)
263 free(authctxt->info);
264 authctxt->info = NULL;
267 i = vasprintf(&authctxt->info, fmt, ap);
270 if (i < 0 || authctxt->info == NULL)
271 fatal("vasprintf failed");
275 auth_log(Authctxt *authctxt, int authenticated, int partial,
276 const char *method, const char *submethod)
278 void (*authlog) (const char *fmt,...) = verbose;
281 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
284 /* Raise logging level */
285 if (authenticated == 1 ||
287 authctxt->failures >= options.max_authtries / 2 ||
288 strcmp(method, "password") == 0)
291 if (authctxt->postponed)
292 authmsg = "Postponed";
296 authmsg = authenticated ? "Accepted" : "Failed";
298 authlog("%s %s%s%s for %s%.100s from %.200s port %d %s%s%s",
301 submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod,
302 authctxt->valid ? "" : "invalid user ",
306 compat20 ? "ssh2" : "ssh1",
307 authctxt->info != NULL ? ": " : "",
308 authctxt->info != NULL ? authctxt->info : "");
309 free(authctxt->info);
310 authctxt->info = NULL;
312 #ifdef CUSTOM_FAILED_LOGIN
313 if (authenticated == 0 && !authctxt->postponed &&
314 (strcmp(method, "password") == 0 ||
315 strncmp(method, "keyboard-interactive", 20) == 0 ||
316 strcmp(method, "challenge-response") == 0))
317 record_failed_login(authctxt->user,
318 get_canonical_hostname(options.use_dns), "ssh");
319 # ifdef WITH_AIXAUTHENTICATE
321 sys_auth_record_login(authctxt->user,
322 get_canonical_hostname(options.use_dns), "ssh", &loginmsg);
325 #ifdef SSH_AUDIT_EVENTS
326 if (authenticated == 0 && !authctxt->postponed)
327 audit_event(audit_classify_auth(method));
333 auth_maxtries_exceeded(Authctxt *authctxt)
335 error("maximum authentication attempts exceeded for "
336 "%s%.100s from %.200s port %d %s",
337 authctxt->valid ? "" : "invalid user ",
341 compat20 ? "ssh2" : "ssh1");
342 packet_disconnect("Too many authentication failures");
347 * Check whether root logins are disallowed.
350 auth_root_allowed(const char *method)
352 switch (options.permit_root_login) {
355 case PERMIT_NO_PASSWD:
356 if (strcmp(method, "publickey") == 0 ||
357 strcmp(method, "hostbased") == 0 ||
358 strcmp(method, "gssapi-with-mic") == 0)
361 case PERMIT_FORCED_ONLY:
362 if (forced_command) {
363 logit("Root login accepted for forced command.");
368 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
374 * Given a template and a passwd structure, build a filename
375 * by substituting % tokenised options. Currently, %% becomes '%',
376 * %h becomes the home directory and %u the username.
378 * This returns a buffer allocated by xmalloc.
381 expand_authorized_keys(const char *filename, struct passwd *pw)
383 char *file, ret[PATH_MAX];
386 file = percent_expand(filename, "h", pw->pw_dir,
387 "u", pw->pw_name, (char *)NULL);
390 * Ensure that filename starts anchored. If not, be backward
391 * compatible and prepend the '%h/'
396 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
397 if (i < 0 || (size_t)i >= sizeof(ret))
398 fatal("expand_authorized_keys: path too long");
400 return (xstrdup(ret));
404 authorized_principals_file(struct passwd *pw)
406 if (options.authorized_principals_file == NULL)
408 return expand_authorized_keys(options.authorized_principals_file, pw);
411 /* return ok if key exists in sysfile or userfile */
413 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
414 const char *sysfile, const char *userfile)
418 HostStatus host_status;
419 struct hostkeys *hostkeys;
420 const struct hostkey_entry *found;
422 hostkeys = init_hostkeys();
423 load_hostkeys(hostkeys, host, sysfile);
424 if (userfile != NULL) {
425 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
426 if (options.strict_modes &&
427 (stat(user_hostfile, &st) == 0) &&
428 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
429 (st.st_mode & 022) != 0)) {
430 logit("Authentication refused for %.100s: "
431 "bad owner or modes for %.200s",
432 pw->pw_name, user_hostfile);
433 auth_debug_add("Ignored %.200s: bad ownership or modes",
436 temporarily_use_uid(pw);
437 load_hostkeys(hostkeys, host, user_hostfile);
442 host_status = check_key_in_hostkeys(hostkeys, key, &found);
443 if (host_status == HOST_REVOKED)
444 error("WARNING: revoked key for %s attempted authentication",
446 else if (host_status == HOST_OK)
447 debug("%s: key for %s found at %s:%ld", __func__,
448 found->host, found->file, found->line);
450 debug("%s: key for host %s not found", __func__, host);
452 free_hostkeys(hostkeys);
458 * Check a given path for security. This is defined as all components
459 * of the path to the file must be owned by either the owner of
460 * of the file or root and no directories must be group or world writable.
462 * XXX Should any specific check be done for sym links ?
464 * Takes a file name, its stat information (preferably from fstat() to
465 * avoid races), the uid of the expected owner, their home directory and an
466 * error buffer plus max size as arguments.
468 * Returns 0 on success and -1 on failure
471 auth_secure_path(const char *name, struct stat *stp, const char *pw_dir,
472 uid_t uid, char *err, size_t errlen)
474 char buf[PATH_MAX], homedir[PATH_MAX];
479 if (realpath(name, buf) == NULL) {
480 snprintf(err, errlen, "realpath %s failed: %s", name,
484 if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL)
487 if (!S_ISREG(stp->st_mode)) {
488 snprintf(err, errlen, "%s is not a regular file", buf);
491 if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) ||
492 (stp->st_mode & 022) != 0) {
493 snprintf(err, errlen, "bad ownership or modes for file %s",
498 /* for each component of the canonical path, walking upwards */
500 if ((cp = dirname(buf)) == NULL) {
501 snprintf(err, errlen, "dirname() failed");
504 strlcpy(buf, cp, sizeof(buf));
506 if (stat(buf, &st) < 0 ||
507 (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) ||
508 (st.st_mode & 022) != 0) {
509 snprintf(err, errlen,
510 "bad ownership or modes for directory %s", buf);
514 /* If are past the homedir then we can stop */
515 if (comparehome && strcmp(homedir, buf) == 0)
519 * dirname should always complete with a "/" path,
520 * but we can be paranoid and check for "." too
522 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
529 * Version of secure_path() that accepts an open file descriptor to
532 * Returns 0 on success and -1 on failure
535 secure_filename(FILE *f, const char *file, struct passwd *pw,
536 char *err, size_t errlen)
540 /* check the open file to avoid races */
541 if (fstat(fileno(f), &st) < 0) {
542 snprintf(err, errlen, "cannot stat file %s: %s",
543 file, strerror(errno));
546 return auth_secure_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen);
550 auth_openfile(const char *file, struct passwd *pw, int strict_modes,
551 int log_missing, char *file_type)
558 if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) {
559 if (log_missing || errno != ENOENT)
560 debug("Could not open %s '%s': %s", file_type, file,
565 if (fstat(fd, &st) < 0) {
569 if (!S_ISREG(st.st_mode)) {
570 logit("User %s %s %s is not a regular file",
571 pw->pw_name, file_type, file);
576 if ((f = fdopen(fd, "r")) == NULL) {
581 secure_filename(f, file, pw, line, sizeof(line)) != 0) {
583 logit("Authentication refused: %s", line);
584 auth_debug_add("Ignored %s: %s", file_type, line);
593 auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
595 return auth_openfile(file, pw, strict_modes, 1, "authorized keys");
599 auth_openprincipals(const char *file, struct passwd *pw, int strict_modes)
601 return auth_openfile(file, pw, strict_modes, 0,
602 "authorized principals");
606 getpwnamallow(const char *user)
608 #ifdef HAVE_LOGIN_CAP
609 extern login_cap_t *lc;
615 struct connection_info *ci = get_connection_info(1, options.use_dns);
618 parse_server_match_config(&options, ci);
620 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
626 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
631 * Windows usernames are case-insensitive. To avoid later problems
632 * when trying to match the username, the user is only allowed to
633 * login if the username is given in the same case as stored in the
636 if (pw != NULL && strcmp(user, pw->pw_name) != 0) {
637 logit("Login name %.100s does not match stored username %.100s",
643 logit("Invalid user %.100s from %.100s",
644 user, get_remote_ipaddr());
645 #ifdef CUSTOM_FAILED_LOGIN
646 record_failed_login(user,
647 get_canonical_hostname(options.use_dns), "ssh");
649 #ifdef SSH_AUDIT_EVENTS
650 audit_event(SSH_INVALID_USER);
651 #endif /* SSH_AUDIT_EVENTS */
654 if (!allowed_user(pw))
656 #ifdef HAVE_LOGIN_CAP
657 if ((lc = login_getpwclass(pw)) == NULL) {
658 debug("unable to get login class: %s", user);
662 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
663 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
664 debug("Approval failure for %s", user);
676 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
678 auth_key_is_revoked(Key *key)
683 if (options.revoked_keys_file == NULL)
685 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
686 SSH_FP_DEFAULT)) == NULL) {
687 r = SSH_ERR_ALLOC_FAIL;
688 error("%s: fingerprint key: %s", __func__, ssh_err(r));
692 r = sshkey_check_revoked(key, options.revoked_keys_file);
695 break; /* not revoked */
696 case SSH_ERR_KEY_REVOKED:
697 error("Authentication key %s %s revoked by file %s",
698 sshkey_type(key), fp, options.revoked_keys_file);
701 error("Error checking authentication key %s %s in "
702 "revoked keys file %s: %s", sshkey_type(key), fp,
703 options.revoked_keys_file, ssh_err(r));
712 return r == 0 ? 0 : 1;
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";