1 /* $OpenBSD: auth.c,v 1.75 2006/08/03 03:34:41 deraadt 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>
54 #include "groupaccess.h"
61 #include "auth-options.h"
70 #include "monitor_wrap.h"
73 extern ServerOptions options;
74 extern int use_privsep;
75 extern Buffer loginmsg;
76 extern struct passwd *privsep_pw;
78 /* Debugging messages */
83 * Check if the user is allowed to log in via ssh. If user is listed
84 * in DenyUsers or one of user's groups is listed in DenyGroups, false
85 * will be returned. If AllowUsers isn't empty and user isn't listed
86 * there, or if AllowGroups isn't empty and one of user's groups isn't
87 * listed there, false will be returned.
88 * If the user's shell is not executable, false will be returned.
89 * Otherwise true is returned.
92 allowed_user(struct passwd * pw)
95 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
99 struct spwd *spw = NULL;
102 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
103 if (!pw || !pw->pw_name)
107 if (!options.use_pam)
108 spw = getspnam(pw->pw_name);
109 #ifdef HAS_SHADOW_EXPIRE
110 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
112 #endif /* HAS_SHADOW_EXPIRE */
113 #endif /* USE_SHADOW */
115 /* grab passwd field for locked account check */
118 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
119 passwd = get_iaf_password(pw);
121 passwd = spw->sp_pwdp;
122 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
124 passwd = pw->pw_passwd;
127 /* check for locked account */
128 if (!options.use_pam && passwd && *passwd) {
131 #ifdef LOCKED_PASSWD_STRING
132 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
135 #ifdef LOCKED_PASSWD_PREFIX
136 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
137 strlen(LOCKED_PASSWD_PREFIX)) == 0)
140 #ifdef LOCKED_PASSWD_SUBSTR
141 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
144 #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
146 #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
148 logit("User %.100s not allowed because account is locked",
155 * Get the shell from the password data. An empty shell field is
156 * legal, and means /bin/sh.
158 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
160 /* deny if shell does not exists or is not executable */
161 if (stat(shell, &st) != 0) {
162 logit("User %.100s not allowed because shell %.100s does not exist",
166 if (S_ISREG(st.st_mode) == 0 ||
167 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
168 logit("User %.100s not allowed because shell %.100s is not executable",
173 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
174 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
175 hostname = get_canonical_hostname(options.use_dns);
176 ipaddr = get_remote_ipaddr();
179 /* Return false if user is listed in DenyUsers */
180 if (options.num_deny_users > 0) {
181 for (i = 0; i < options.num_deny_users; i++)
182 if (match_user(pw->pw_name, hostname, ipaddr,
183 options.deny_users[i])) {
184 logit("User %.100s from %.100s not allowed "
185 "because listed in DenyUsers",
186 pw->pw_name, hostname);
190 /* Return false if AllowUsers isn't empty and user isn't listed there */
191 if (options.num_allow_users > 0) {
192 for (i = 0; i < options.num_allow_users; i++)
193 if (match_user(pw->pw_name, hostname, ipaddr,
194 options.allow_users[i]))
196 /* i < options.num_allow_users iff we break for loop */
197 if (i >= options.num_allow_users) {
198 logit("User %.100s from %.100s not allowed because "
199 "not listed in AllowUsers", pw->pw_name, hostname);
203 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
204 /* Get the user's group access list (primary and supplementary) */
205 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
206 logit("User %.100s from %.100s not allowed because "
207 "not in any group", pw->pw_name, hostname);
211 /* Return false if one of user's groups is listed in DenyGroups */
212 if (options.num_deny_groups > 0)
213 if (ga_match(options.deny_groups,
214 options.num_deny_groups)) {
216 logit("User %.100s from %.100s not allowed "
217 "because a group is listed in DenyGroups",
218 pw->pw_name, hostname);
222 * Return false if AllowGroups isn't empty and one of user's groups
225 if (options.num_allow_groups > 0)
226 if (!ga_match(options.allow_groups,
227 options.num_allow_groups)) {
229 logit("User %.100s from %.100s not allowed "
230 "because none of user's groups are listed "
231 "in AllowGroups", pw->pw_name, hostname);
237 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
238 if (!sys_auth_allowed_user(pw, &loginmsg))
242 /* We found no reason not to let this user try to log on... */
247 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
249 void (*authlog) (const char *fmt,...) = verbose;
252 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
255 /* Raise logging level */
256 if (authenticated == 1 ||
258 authctxt->failures >= options.max_authtries / 2 ||
259 strcmp(method, "password") == 0)
262 if (authctxt->postponed)
263 authmsg = "Postponed";
265 authmsg = authenticated ? "Accepted" : "Failed";
267 authlog("%s %s for %s%.100s from %.200s port %d%s",
270 authctxt->valid ? "" : "invalid user ",
276 #ifdef CUSTOM_FAILED_LOGIN
277 if (authenticated == 0 && !authctxt->postponed &&
278 (strcmp(method, "password") == 0 ||
279 strncmp(method, "keyboard-interactive", 20) == 0 ||
280 strcmp(method, "challenge-response") == 0))
281 record_failed_login(authctxt->user,
282 get_canonical_hostname(options.use_dns), "ssh");
283 # ifdef WITH_AIXAUTHENTICATE
285 sys_auth_record_login(authctxt->user,
286 get_canonical_hostname(options.use_dns), "ssh", &loginmsg);
289 #ifdef SSH_AUDIT_EVENTS
290 if (authenticated == 0 && !authctxt->postponed)
291 audit_event(audit_classify_auth(method));
296 * Check whether root logins are disallowed.
299 auth_root_allowed(char *method)
301 switch (options.permit_root_login) {
304 case PERMIT_NO_PASSWD:
305 if (strcmp(method, "password") != 0)
308 case PERMIT_FORCED_ONLY:
309 if (forced_command) {
310 logit("Root login accepted for forced command.");
315 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
321 * Given a template and a passwd structure, build a filename
322 * by substituting % tokenised options. Currently, %% becomes '%',
323 * %h becomes the home directory and %u the username.
325 * This returns a buffer allocated by xmalloc.
328 expand_authorized_keys(const char *filename, struct passwd *pw)
330 char *file, ret[MAXPATHLEN];
333 file = percent_expand(filename, "h", pw->pw_dir,
334 "u", pw->pw_name, (char *)NULL);
337 * Ensure that filename starts anchored. If not, be backward
338 * compatible and prepend the '%h/'
343 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
344 if (i < 0 || (size_t)i >= sizeof(ret))
345 fatal("expand_authorized_keys: path too long");
347 return (xstrdup(ret));
351 authorized_keys_file(struct passwd *pw)
353 return expand_authorized_keys(options.authorized_keys_file, pw);
357 authorized_keys_file2(struct passwd *pw)
359 return expand_authorized_keys(options.authorized_keys_file2, pw);
362 /* return ok if key exists in sysfile or userfile */
364 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
365 const char *sysfile, const char *userfile)
370 HostStatus host_status;
372 /* Check if we know the host and its host key. */
373 found = key_new(key->type);
374 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
376 if (host_status != HOST_OK && userfile != NULL) {
377 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
378 if (options.strict_modes &&
379 (stat(user_hostfile, &st) == 0) &&
380 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
381 (st.st_mode & 022) != 0)) {
382 logit("Authentication refused for %.100s: "
383 "bad owner or modes for %.200s",
384 pw->pw_name, user_hostfile);
386 temporarily_use_uid(pw);
387 host_status = check_host_in_hostfile(user_hostfile,
388 host, key, found, NULL);
391 xfree(user_hostfile);
395 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
396 "ok" : "not found", host);
402 * Check a given file for security. This is defined as all components
403 * of the path to the file must be owned by either the owner of
404 * of the file or root and no directories must be group or world writable.
406 * XXX Should any specific check be done for sym links ?
408 * Takes an open file descriptor, the file name, a uid and and
409 * error buffer plus max size as arguments.
411 * Returns 0 on success and -1 on failure
414 secure_filename(FILE *f, const char *file, struct passwd *pw,
415 char *err, size_t errlen)
417 uid_t uid = pw->pw_uid;
418 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
423 if (realpath(file, buf) == NULL) {
424 snprintf(err, errlen, "realpath %s failed: %s", file,
428 if (realpath(pw->pw_dir, homedir) != NULL)
431 /* check the open file to avoid races */
432 if (fstat(fileno(f), &st) < 0 ||
433 (st.st_uid != 0 && st.st_uid != uid) ||
434 (st.st_mode & 022) != 0) {
435 snprintf(err, errlen, "bad ownership or modes for file %s",
440 /* for each component of the canonical path, walking upwards */
442 if ((cp = dirname(buf)) == NULL) {
443 snprintf(err, errlen, "dirname() failed");
446 strlcpy(buf, cp, sizeof(buf));
448 debug3("secure_filename: checking '%s'", buf);
449 if (stat(buf, &st) < 0 ||
450 (st.st_uid != 0 && st.st_uid != uid) ||
451 (st.st_mode & 022) != 0) {
452 snprintf(err, errlen,
453 "bad ownership or modes for directory %s", buf);
457 /* If are passed the homedir then we can stop */
458 if (comparehome && strcmp(homedir, buf) == 0) {
459 debug3("secure_filename: terminating check at '%s'",
464 * dirname should always complete with a "/" path,
465 * but we can be paranoid and check for "." too
467 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
474 getpwnamallow(const char *user)
476 #ifdef HAVE_LOGIN_CAP
477 extern login_cap_t *lc;
484 parse_server_match_config(&options, user,
485 get_canonical_hostname(options.use_dns), get_remote_ipaddr());
489 logit("Invalid user %.100s from %.100s",
490 user, get_remote_ipaddr());
491 #ifdef CUSTOM_FAILED_LOGIN
492 record_failed_login(user,
493 get_canonical_hostname(options.use_dns), "ssh");
495 #ifdef SSH_AUDIT_EVENTS
496 audit_event(SSH_INVALID_USER);
497 #endif /* SSH_AUDIT_EVENTS */
500 if (!allowed_user(pw))
502 #ifdef HAVE_LOGIN_CAP
503 if ((lc = login_getclass(pw->pw_class)) == NULL) {
504 debug("unable to get login class: %s", user);
508 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
509 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
510 debug("Approval failure for %s", user);
523 auth_debug_add(const char *fmt,...)
528 if (!auth_debug_init)
532 vsnprintf(buf, sizeof(buf), fmt, args);
534 buffer_put_cstring(&auth_debug, buf);
538 auth_debug_send(void)
542 if (!auth_debug_init)
544 while (buffer_len(&auth_debug)) {
545 msg = buffer_get_string(&auth_debug, NULL);
546 packet_send_debug("%s", msg);
552 auth_debug_reset(void)
555 buffer_clear(&auth_debug);
557 buffer_init(&auth_debug);
565 static struct passwd fake;
567 memset(&fake, 0, sizeof(fake));
568 fake.pw_name = "NOUSER";
570 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
571 fake.pw_gecos = "NOUSER";
572 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
573 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
574 #ifdef HAVE_PW_CLASS_IN_PASSWD
577 fake.pw_dir = "/nonexist";
578 fake.pw_shell = "/nonexist";