1 /* $OpenBSD: auth.c,v 1.66 2006/03/25 13:17:01 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>
47 #include "groupaccess.h"
51 #include "auth-options.h"
60 #include "monitor_wrap.h"
63 extern ServerOptions options;
64 extern Buffer loginmsg;
66 /* Debugging messages */
71 * Check if the user is allowed to log in via ssh. If user is listed
72 * in DenyUsers or one of user's groups is listed in DenyGroups, false
73 * will be returned. If AllowUsers isn't empty and user isn't listed
74 * there, or if AllowGroups isn't empty and one of user's groups isn't
75 * listed there, false will be returned.
76 * If the user's shell is not executable, false will be returned.
77 * Otherwise true is returned.
80 allowed_user(struct passwd * pw)
83 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
87 struct spwd *spw = NULL;
90 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
91 if (!pw || !pw->pw_name)
96 spw = getspnam(pw->pw_name);
97 #ifdef HAS_SHADOW_EXPIRE
98 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
100 #endif /* HAS_SHADOW_EXPIRE */
101 #endif /* USE_SHADOW */
103 /* grab passwd field for locked account check */
106 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
107 passwd = get_iaf_password(pw);
109 passwd = spw->sp_pwdp;
110 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
112 passwd = pw->pw_passwd;
115 /* check for locked account */
116 if (!options.use_pam && passwd && *passwd) {
119 #ifdef LOCKED_PASSWD_STRING
120 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
123 #ifdef LOCKED_PASSWD_PREFIX
124 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
125 strlen(LOCKED_PASSWD_PREFIX)) == 0)
128 #ifdef LOCKED_PASSWD_SUBSTR
129 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
132 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
134 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
136 logit("User %.100s not allowed because account is locked",
143 * Get the shell from the password data. An empty shell field is
144 * legal, and means /bin/sh.
146 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
148 /* deny if shell does not exists or is not executable */
149 if (stat(shell, &st) != 0) {
150 logit("User %.100s not allowed because shell %.100s does not exist",
154 if (S_ISREG(st.st_mode) == 0 ||
155 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
156 logit("User %.100s not allowed because shell %.100s is not executable",
161 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
162 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
163 hostname = get_canonical_hostname(options.use_dns);
164 ipaddr = get_remote_ipaddr();
167 /* Return false if user is listed in DenyUsers */
168 if (options.num_deny_users > 0) {
169 for (i = 0; i < options.num_deny_users; i++)
170 if (match_user(pw->pw_name, hostname, ipaddr,
171 options.deny_users[i])) {
172 logit("User %.100s from %.100s not allowed "
173 "because listed in DenyUsers",
174 pw->pw_name, hostname);
178 /* Return false if AllowUsers isn't empty and user isn't listed there */
179 if (options.num_allow_users > 0) {
180 for (i = 0; i < options.num_allow_users; i++)
181 if (match_user(pw->pw_name, hostname, ipaddr,
182 options.allow_users[i]))
184 /* i < options.num_allow_users iff we break for loop */
185 if (i >= options.num_allow_users) {
186 logit("User %.100s from %.100s not allowed because "
187 "not listed in AllowUsers", pw->pw_name, hostname);
191 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
192 /* Get the user's group access list (primary and supplementary) */
193 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
194 logit("User %.100s from %.100s not allowed because "
195 "not in any group", pw->pw_name, hostname);
199 /* Return false if one of user's groups is listed in DenyGroups */
200 if (options.num_deny_groups > 0)
201 if (ga_match(options.deny_groups,
202 options.num_deny_groups)) {
204 logit("User %.100s from %.100s not allowed "
205 "because a group is listed in DenyGroups",
206 pw->pw_name, hostname);
210 * Return false if AllowGroups isn't empty and one of user's groups
213 if (options.num_allow_groups > 0)
214 if (!ga_match(options.allow_groups,
215 options.num_allow_groups)) {
217 logit("User %.100s from %.100s not allowed "
218 "because none of user's groups are listed "
219 "in AllowGroups", pw->pw_name, hostname);
225 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
226 if (!sys_auth_allowed_user(pw, &loginmsg))
230 /* We found no reason not to let this user try to log on... */
235 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
237 void (*authlog) (const char *fmt,...) = verbose;
240 /* Raise logging level */
241 if (authenticated == 1 ||
243 authctxt->failures >= options.max_authtries / 2 ||
244 strcmp(method, "password") == 0)
247 if (authctxt->postponed)
248 authmsg = "Postponed";
250 authmsg = authenticated ? "Accepted" : "Failed";
252 authlog("%s %s for %s%.100s from %.200s port %d%s",
255 authctxt->valid ? "" : "invalid user ",
261 #ifdef CUSTOM_FAILED_LOGIN
262 if (authenticated == 0 && !authctxt->postponed &&
263 (strcmp(method, "password") == 0 ||
264 strncmp(method, "keyboard-interactive", 20) == 0 ||
265 strcmp(method, "challenge-response") == 0))
266 record_failed_login(authctxt->user,
267 get_canonical_hostname(options.use_dns), "ssh");
269 #ifdef SSH_AUDIT_EVENTS
270 if (authenticated == 0 && !authctxt->postponed) {
271 ssh_audit_event_t event;
273 debug3("audit failed auth attempt, method %s euid %d",
274 method, (int)geteuid());
276 * Because the auth loop is used in both monitor and slave,
277 * we must be careful to send each event only once and with
278 * enough privs to write the event.
280 event = audit_classify_auth(method);
282 case SSH_AUTH_FAIL_NONE:
283 case SSH_AUTH_FAIL_PASSWD:
284 case SSH_AUTH_FAIL_KBDINT:
288 case SSH_AUTH_FAIL_PUBKEY:
289 case SSH_AUTH_FAIL_HOSTBASED:
290 case SSH_AUTH_FAIL_GSSAPI:
292 * This is required to handle the case where privsep
293 * is enabled but it's root logging in, since
294 * use_privsep won't be cleared until after a
300 PRIVSEP(audit_event(event));
303 error("unknown authentication audit event %d", event);
310 * Check whether root logins are disallowed.
313 auth_root_allowed(char *method)
315 switch (options.permit_root_login) {
318 case PERMIT_NO_PASSWD:
319 if (strcmp(method, "password") != 0)
322 case PERMIT_FORCED_ONLY:
323 if (forced_command) {
324 logit("Root login accepted for forced command.");
329 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
335 * Given a template and a passwd structure, build a filename
336 * by substituting % tokenised options. Currently, %% becomes '%',
337 * %h becomes the home directory and %u the username.
339 * This returns a buffer allocated by xmalloc.
342 expand_authorized_keys(const char *filename, struct passwd *pw)
344 char *file, ret[MAXPATHLEN];
347 file = percent_expand(filename, "h", pw->pw_dir,
348 "u", pw->pw_name, (char *)NULL);
351 * Ensure that filename starts anchored. If not, be backward
352 * compatible and prepend the '%h/'
357 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
358 if (i < 0 || (size_t)i >= sizeof(ret))
359 fatal("expand_authorized_keys: path too long");
361 return (xstrdup(ret));
365 authorized_keys_file(struct passwd *pw)
367 return expand_authorized_keys(options.authorized_keys_file, pw);
371 authorized_keys_file2(struct passwd *pw)
373 return expand_authorized_keys(options.authorized_keys_file2, pw);
376 /* return ok if key exists in sysfile or userfile */
378 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
379 const char *sysfile, const char *userfile)
384 HostStatus host_status;
386 /* Check if we know the host and its host key. */
387 found = key_new(key->type);
388 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
390 if (host_status != HOST_OK && userfile != NULL) {
391 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
392 if (options.strict_modes &&
393 (stat(user_hostfile, &st) == 0) &&
394 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
395 (st.st_mode & 022) != 0)) {
396 logit("Authentication refused for %.100s: "
397 "bad owner or modes for %.200s",
398 pw->pw_name, user_hostfile);
400 temporarily_use_uid(pw);
401 host_status = check_host_in_hostfile(user_hostfile,
402 host, key, found, NULL);
405 xfree(user_hostfile);
409 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
410 "ok" : "not found", host);
416 * Check a given file for security. This is defined as all components
417 * of the path to the file must be owned by either the owner of
418 * of the file or root and no directories must be group or world writable.
420 * XXX Should any specific check be done for sym links ?
422 * Takes an open file descriptor, the file name, a uid and and
423 * error buffer plus max size as arguments.
425 * Returns 0 on success and -1 on failure
428 secure_filename(FILE *f, const char *file, struct passwd *pw,
429 char *err, size_t errlen)
431 uid_t uid = pw->pw_uid;
432 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
437 if (realpath(file, buf) == NULL) {
438 snprintf(err, errlen, "realpath %s failed: %s", file,
442 if (realpath(pw->pw_dir, homedir) != NULL)
445 /* check the open file to avoid races */
446 if (fstat(fileno(f), &st) < 0 ||
447 (st.st_uid != 0 && st.st_uid != uid) ||
448 (st.st_mode & 022) != 0) {
449 snprintf(err, errlen, "bad ownership or modes for file %s",
454 /* for each component of the canonical path, walking upwards */
456 if ((cp = dirname(buf)) == NULL) {
457 snprintf(err, errlen, "dirname() failed");
460 strlcpy(buf, cp, sizeof(buf));
462 debug3("secure_filename: checking '%s'", buf);
463 if (stat(buf, &st) < 0 ||
464 (st.st_uid != 0 && st.st_uid != uid) ||
465 (st.st_mode & 022) != 0) {
466 snprintf(err, errlen,
467 "bad ownership or modes for directory %s", buf);
471 /* If are passed the homedir then we can stop */
472 if (comparehome && strcmp(homedir, buf) == 0) {
473 debug3("secure_filename: terminating check at '%s'",
478 * dirname should always complete with a "/" path,
479 * but we can be paranoid and check for "." too
481 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
488 getpwnamallow(const char *user)
490 #ifdef HAVE_LOGIN_CAP
491 extern login_cap_t *lc;
500 logit("Invalid user %.100s from %.100s",
501 user, get_remote_ipaddr());
502 #ifdef CUSTOM_FAILED_LOGIN
503 record_failed_login(user,
504 get_canonical_hostname(options.use_dns), "ssh");
506 #ifdef SSH_AUDIT_EVENTS
507 audit_event(SSH_INVALID_USER);
508 #endif /* SSH_AUDIT_EVENTS */
511 if (!allowed_user(pw))
513 #ifdef HAVE_LOGIN_CAP
514 if ((lc = login_getclass(pw->pw_class)) == NULL) {
515 debug("unable to get login class: %s", user);
519 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
520 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
521 debug("Approval failure for %s", user);
534 auth_debug_add(const char *fmt,...)
539 if (!auth_debug_init)
543 vsnprintf(buf, sizeof(buf), fmt, args);
545 buffer_put_cstring(&auth_debug, buf);
549 auth_debug_send(void)
553 if (!auth_debug_init)
555 while (buffer_len(&auth_debug)) {
556 msg = buffer_get_string(&auth_debug, NULL);
557 packet_send_debug("%s", msg);
563 auth_debug_reset(void)
566 buffer_clear(&auth_debug);
568 buffer_init(&auth_debug);
576 static struct passwd fake;
578 memset(&fake, 0, sizeof(fake));
579 fake.pw_name = "NOUSER";
581 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
582 fake.pw_gecos = "NOUSER";
583 fake.pw_uid = (uid_t)-1;
584 fake.pw_gid = (gid_t)-1;
585 #ifdef HAVE_PW_CLASS_IN_PASSWD
588 fake.pw_dir = "/nonexist";
589 fake.pw_shell = "/nonexist";