2 * Copyright (c) 2000 Markus Friedl. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 #include <sys/types.h>
46 #include "groupaccess.h"
50 #include "auth-options.h"
59 #include "monitor_wrap.h"
62 extern ServerOptions options;
63 extern Buffer loginmsg;
65 /* Debugging messages */
70 * Check if the user is allowed to log in via ssh. If user is listed
71 * in DenyUsers or one of user's groups is listed in DenyGroups, false
72 * will be returned. If AllowUsers isn't empty and user isn't listed
73 * there, or if AllowGroups isn't empty and one of user's groups isn't
74 * listed there, false will be returned.
75 * If the user's shell is not executable, false will be returned.
76 * Otherwise true is returned.
79 allowed_user(struct passwd * pw)
82 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
86 struct spwd *spw = NULL;
89 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
90 if (!pw || !pw->pw_name)
95 spw = getspnam(pw->pw_name);
96 #ifdef HAS_SHADOW_EXPIRE
97 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
99 #endif /* HAS_SHADOW_EXPIRE */
100 #endif /* USE_SHADOW */
102 /* grab passwd field for locked account check */
105 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
106 passwd = get_iaf_password(pw);
108 passwd = spw->sp_pwdp;
109 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
111 passwd = pw->pw_passwd;
114 /* check for locked account */
115 if (!options.use_pam && passwd && *passwd) {
118 #ifdef LOCKED_PASSWD_STRING
119 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
122 #ifdef LOCKED_PASSWD_PREFIX
123 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
124 strlen(LOCKED_PASSWD_PREFIX)) == 0)
127 #ifdef LOCKED_PASSWD_SUBSTR
128 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
131 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
133 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
135 logit("User %.100s not allowed because account is locked",
142 * Get the shell from the password data. An empty shell field is
143 * legal, and means /bin/sh.
145 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
147 /* deny if shell does not exists or is not executable */
148 if (stat(shell, &st) != 0) {
149 logit("User %.100s not allowed because shell %.100s does not exist",
153 if (S_ISREG(st.st_mode) == 0 ||
154 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
155 logit("User %.100s not allowed because shell %.100s is not executable",
160 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
161 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
162 hostname = get_canonical_hostname(options.use_dns);
163 ipaddr = get_remote_ipaddr();
166 /* Return false if user is listed in DenyUsers */
167 if (options.num_deny_users > 0) {
168 for (i = 0; i < options.num_deny_users; i++)
169 if (match_user(pw->pw_name, hostname, ipaddr,
170 options.deny_users[i])) {
171 logit("User %.100s from %.100s not allowed "
172 "because listed in DenyUsers",
173 pw->pw_name, hostname);
177 /* Return false if AllowUsers isn't empty and user isn't listed there */
178 if (options.num_allow_users > 0) {
179 for (i = 0; i < options.num_allow_users; i++)
180 if (match_user(pw->pw_name, hostname, ipaddr,
181 options.allow_users[i]))
183 /* i < options.num_allow_users iff we break for loop */
184 if (i >= options.num_allow_users) {
185 logit("User %.100s from %.100s not allowed because "
186 "not listed in AllowUsers", pw->pw_name, hostname);
190 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
191 /* Get the user's group access list (primary and supplementary) */
192 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
193 logit("User %.100s from %.100s not allowed because "
194 "not in any group", pw->pw_name, hostname);
198 /* Return false if one of user's groups is listed in DenyGroups */
199 if (options.num_deny_groups > 0)
200 if (ga_match(options.deny_groups,
201 options.num_deny_groups)) {
203 logit("User %.100s from %.100s not allowed "
204 "because a group is listed in DenyGroups",
205 pw->pw_name, hostname);
209 * Return false if AllowGroups isn't empty and one of user's groups
212 if (options.num_allow_groups > 0)
213 if (!ga_match(options.allow_groups,
214 options.num_allow_groups)) {
216 logit("User %.100s from %.100s not allowed "
217 "because none of user's groups are listed "
218 "in AllowGroups", pw->pw_name, hostname);
224 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
225 if (!sys_auth_allowed_user(pw, &loginmsg))
229 /* We found no reason not to let this user try to log on... */
234 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
236 void (*authlog) (const char *fmt,...) = verbose;
239 /* Raise logging level */
240 if (authenticated == 1 ||
242 authctxt->failures >= options.max_authtries / 2 ||
243 strcmp(method, "password") == 0)
246 if (authctxt->postponed)
247 authmsg = "Postponed";
249 authmsg = authenticated ? "Accepted" : "Failed";
251 authlog("%s %s for %s%.100s from %.200s port %d%s",
254 authctxt->valid ? "" : "invalid user ",
260 #ifdef CUSTOM_FAILED_LOGIN
261 if (authenticated == 0 && !authctxt->postponed &&
262 (strcmp(method, "password") == 0 ||
263 strncmp(method, "keyboard-interactive", 20) == 0 ||
264 strcmp(method, "challenge-response") == 0))
265 record_failed_login(authctxt->user,
266 get_canonical_hostname(options.use_dns), "ssh");
268 #ifdef SSH_AUDIT_EVENTS
269 if (authenticated == 0 && !authctxt->postponed) {
270 ssh_audit_event_t event;
272 debug3("audit failed auth attempt, method %s euid %d",
273 method, (int)geteuid());
275 * Because the auth loop is used in both monitor and slave,
276 * we must be careful to send each event only once and with
277 * enough privs to write the event.
279 event = audit_classify_auth(method);
281 case SSH_AUTH_FAIL_NONE:
282 case SSH_AUTH_FAIL_PASSWD:
283 case SSH_AUTH_FAIL_KBDINT:
287 case SSH_AUTH_FAIL_PUBKEY:
288 case SSH_AUTH_FAIL_HOSTBASED:
289 case SSH_AUTH_FAIL_GSSAPI:
291 * This is required to handle the case where privsep
292 * is enabled but it's root logging in, since
293 * use_privsep won't be cleared until after a
299 PRIVSEP(audit_event(event));
302 error("unknown authentication audit event %d", event);
309 * Check whether root logins are disallowed.
312 auth_root_allowed(char *method)
314 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)
346 file = percent_expand(filename, "h", pw->pw_dir,
347 "u", pw->pw_name, (char *)NULL);
350 * Ensure that filename starts anchored. If not, be backward
351 * compatible and prepend the '%h/'
356 ret = xmalloc(MAXPATHLEN);
357 if (strlcpy(ret, pw->pw_dir, MAXPATHLEN) >= MAXPATHLEN ||
358 strlcat(ret, "/", MAXPATHLEN) >= MAXPATHLEN ||
359 strlcat(ret, file, MAXPATHLEN) >= MAXPATHLEN)
360 fatal("expand_authorized_keys: path too long");
367 authorized_keys_file(struct passwd *pw)
369 return expand_authorized_keys(options.authorized_keys_file, pw);
373 authorized_keys_file2(struct passwd *pw)
375 return expand_authorized_keys(options.authorized_keys_file2, 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)
386 HostStatus host_status;
388 /* Check if we know the host and its host key. */
389 found = key_new(key->type);
390 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
392 if (host_status != HOST_OK && userfile != NULL) {
393 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
394 if (options.strict_modes &&
395 (stat(user_hostfile, &st) == 0) &&
396 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
397 (st.st_mode & 022) != 0)) {
398 logit("Authentication refused for %.100s: "
399 "bad owner or modes for %.200s",
400 pw->pw_name, user_hostfile);
402 temporarily_use_uid(pw);
403 host_status = check_host_in_hostfile(user_hostfile,
404 host, key, found, NULL);
407 xfree(user_hostfile);
411 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
412 "ok" : "not found", host);
418 * Check a given file for security. This is defined as all components
419 * of the path to the file must be owned by either the owner of
420 * of the file or root and no directories must be group or world writable.
422 * XXX Should any specific check be done for sym links ?
424 * Takes an open file descriptor, the file name, a uid and and
425 * error buffer plus max size as arguments.
427 * Returns 0 on success and -1 on failure
430 secure_filename(FILE *f, const char *file, struct passwd *pw,
431 char *err, size_t errlen)
433 uid_t uid = pw->pw_uid;
434 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
439 if (realpath(file, buf) == NULL) {
440 snprintf(err, errlen, "realpath %s failed: %s", file,
444 if (realpath(pw->pw_dir, homedir) != NULL)
447 /* check the open file to avoid races */
448 if (fstat(fileno(f), &st) < 0 ||
449 (st.st_uid != 0 && st.st_uid != uid) ||
450 (st.st_mode & 022) != 0) {
451 snprintf(err, errlen, "bad ownership or modes for file %s",
456 /* for each component of the canonical path, walking upwards */
458 if ((cp = dirname(buf)) == NULL) {
459 snprintf(err, errlen, "dirname() failed");
462 strlcpy(buf, cp, sizeof(buf));
464 debug3("secure_filename: checking '%s'", buf);
465 if (stat(buf, &st) < 0 ||
466 (st.st_uid != 0 && st.st_uid != uid) ||
467 (st.st_mode & 022) != 0) {
468 snprintf(err, errlen,
469 "bad ownership or modes for directory %s", buf);
473 /* If are passed the homedir then we can stop */
474 if (comparehome && strcmp(homedir, buf) == 0) {
475 debug3("secure_filename: terminating check at '%s'",
480 * dirname should always complete with a "/" path,
481 * but we can be paranoid and check for "." too
483 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
490 getpwnamallow(const char *user)
492 #ifdef HAVE_LOGIN_CAP
493 extern login_cap_t *lc;
502 logit("Invalid user %.100s from %.100s",
503 user, get_remote_ipaddr());
504 #ifdef CUSTOM_FAILED_LOGIN
505 record_failed_login(user,
506 get_canonical_hostname(options.use_dns), "ssh");
508 #ifdef SSH_AUDIT_EVENTS
509 audit_event(SSH_INVALID_USER);
510 #endif /* SSH_AUDIT_EVENTS */
513 if (!allowed_user(pw))
515 #ifdef HAVE_LOGIN_CAP
516 if ((lc = login_getclass(pw->pw_class)) == NULL) {
517 debug("unable to get login class: %s", user);
521 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
522 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
523 debug("Approval failure for %s", user);
536 auth_debug_add(const char *fmt,...)
541 if (!auth_debug_init)
545 vsnprintf(buf, sizeof(buf), fmt, args);
547 buffer_put_cstring(&auth_debug, buf);
551 auth_debug_send(void)
555 if (!auth_debug_init)
557 while (buffer_len(&auth_debug)) {
558 msg = buffer_get_string(&auth_debug, NULL);
559 packet_send_debug("%s", msg);
565 auth_debug_reset(void)
568 buffer_clear(&auth_debug);
570 buffer_init(&auth_debug);
578 static struct passwd fake;
580 memset(&fake, 0, sizeof(fake));
581 fake.pw_name = "NOUSER";
583 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
584 fake.pw_gecos = "NOUSER";
585 fake.pw_uid = (uid_t)-1;
586 fake.pw_gid = (gid_t)-1;
587 #ifdef HAVE_PW_CLASS_IN_PASSWD
590 fake.pw_dir = "/nonexist";
591 fake.pw_shell = "/nonexist";