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.
26 RCSID("$OpenBSD: auth.c,v 1.41 2002/03/19 15:31:47 markus Exp $");
31 #if defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW)
33 #endif /* defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) */
41 #include "groupaccess.h"
45 #include "auth-options.h"
50 #include "tildexpand.h"
54 extern ServerOptions options;
57 * Check if the user is allowed to log in via ssh. If user is listed
58 * in DenyUsers or one of user's groups is listed in DenyGroups, false
59 * will be returned. If AllowUsers isn't empty and user isn't listed
60 * there, or if AllowGroups isn't empty and one of user's groups isn't
61 * listed there, false will be returned.
62 * If the user's shell is not executable, false will be returned.
63 * Otherwise true is returned.
66 allowed_user(struct passwd * pw)
69 const char *hostname = NULL, *ipaddr = NULL;
72 #ifdef WITH_AIXAUTHENTICATE
74 #endif /* WITH_AIXAUTHENTICATE */
75 #if !defined(USE_PAM) && defined(HAVE_SHADOW_H) && \
76 !defined(DISABLE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
79 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
80 if (!pw || !pw->pw_name)
83 #define DAY (24L * 60 * 60) /* 1 day in seconds */
84 spw = getspnam(pw->pw_name);
86 time_t today = time(NULL) / DAY;
87 debug3("allowed_user: today %d sp_expire %d sp_lstchg %d"
88 " sp_max %d", (int)today, (int)spw->sp_expire,
89 (int)spw->sp_lstchg, (int)spw->sp_max);
92 * We assume account and password expiration occurs the
93 * day after the day specified.
95 if (spw->sp_expire != -1 && today > spw->sp_expire) {
96 log("Account %.100s has expired", pw->pw_name);
100 if (spw->sp_lstchg == 0) {
101 log("User %.100s password has expired (root forced)",
106 if (spw->sp_max != -1 &&
107 today > spw->sp_lstchg + spw->sp_max) {
108 log("User %.100s password has expired (password aged)",
114 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
115 if (!pw || !pw->pw_name)
120 * Get the shell from the password data. An empty shell field is
121 * legal, and means /bin/sh.
123 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
125 /* deny if shell does not exists or is not executable */
126 if (stat(shell, &st) != 0) {
127 log("User %.100s not allowed because shell %.100s does not exist",
131 if (S_ISREG(st.st_mode) == 0 ||
132 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
133 log("User %.100s not allowed because shell %.100s is not executable",
138 if (options.num_deny_users > 0 || options.num_allow_users > 0) {
139 hostname = get_canonical_hostname(options.verify_reverse_mapping);
140 ipaddr = get_remote_ipaddr();
143 /* Return false if user is listed in DenyUsers */
144 if (options.num_deny_users > 0) {
145 for (i = 0; i < options.num_deny_users; i++)
146 if (match_user(pw->pw_name, hostname, ipaddr,
147 options.deny_users[i])) {
148 log("User %.100s not allowed because listed in DenyUsers",
153 /* Return false if AllowUsers isn't empty and user isn't listed there */
154 if (options.num_allow_users > 0) {
155 for (i = 0; i < options.num_allow_users; i++)
156 if (match_user(pw->pw_name, hostname, ipaddr,
157 options.allow_users[i]))
159 /* i < options.num_allow_users iff we break for loop */
160 if (i >= options.num_allow_users) {
161 log("User %.100s not allowed because not listed in AllowUsers",
166 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
167 /* Get the user's group access list (primary and supplementary) */
168 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
169 log("User %.100s not allowed because not in any group",
174 /* Return false if one of user's groups is listed in DenyGroups */
175 if (options.num_deny_groups > 0)
176 if (ga_match(options.deny_groups,
177 options.num_deny_groups)) {
179 log("User %.100s not allowed because a group is listed in DenyGroups",
184 * Return false if AllowGroups isn't empty and one of user's groups
187 if (options.num_allow_groups > 0)
188 if (!ga_match(options.allow_groups,
189 options.num_allow_groups)) {
191 log("User %.100s not allowed because none of user's groups are listed in AllowGroups",
198 #ifdef WITH_AIXAUTHENTICATE
199 if (loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &loginmsg) != 0) {
200 if (loginmsg && *loginmsg) {
201 /* Remove embedded newlines (if any) */
203 for (p = loginmsg; *p; p++) {
207 /* Remove trailing newline */
209 log("Login restricted for %s: %.100s", pw->pw_name, loginmsg);
213 #endif /* WITH_AIXAUTHENTICATE */
215 /* We found no reason not to let this user try to log on... */
222 Authctxt *authctxt = xmalloc(sizeof(*authctxt));
223 memset(authctxt, 0, sizeof(*authctxt));
228 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
230 void (*authlog) (const char *fmt,...) = verbose;
233 /* Raise logging level */
234 if (authenticated == 1 ||
236 authctxt->failures >= AUTH_FAIL_LOG ||
237 strcmp(method, "password") == 0)
240 if (authctxt->postponed)
241 authmsg = "Postponed";
243 authmsg = authenticated ? "Accepted" : "Failed";
245 authlog("%s %s for %s%.100s from %.200s port %d%s",
248 authctxt->valid ? "" : "illegal user ",
256 * Check whether root logins are disallowed.
259 auth_root_allowed(char *method)
261 switch (options.permit_root_login) {
265 case PERMIT_NO_PASSWD:
266 if (strcmp(method, "password") != 0)
269 case PERMIT_FORCED_ONLY:
270 if (forced_command) {
271 log("Root login accepted for forced command.");
276 log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
282 * Given a template and a passwd structure, build a filename
283 * by substituting % tokenised options. Currently, %% becomes '%',
284 * %h becomes the home directory and %u the username.
286 * This returns a buffer allocated by xmalloc.
289 expand_filename(const char *filename, struct passwd *pw)
296 * Build the filename string in the buffer by making the appropriate
297 * substitutions to the given file name.
299 buffer_init(&buffer);
300 for (cp = filename; *cp; cp++) {
301 if (cp[0] == '%' && cp[1] == '%') {
302 buffer_append(&buffer, "%", 1);
306 if (cp[0] == '%' && cp[1] == 'h') {
307 buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
311 if (cp[0] == '%' && cp[1] == 'u') {
312 buffer_append(&buffer, pw->pw_name,
313 strlen(pw->pw_name));
317 buffer_append(&buffer, cp, 1);
319 buffer_append(&buffer, "\0", 1);
322 * Ensure that filename starts anchored. If not, be backward
323 * compatible and prepend the '%h/'
325 file = xmalloc(MAXPATHLEN);
326 cp = buffer_ptr(&buffer);
328 snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
330 strlcpy(file, cp, MAXPATHLEN);
332 buffer_free(&buffer);
337 authorized_keys_file(struct passwd *pw)
339 return expand_filename(options.authorized_keys_file, pw);
343 authorized_keys_file2(struct passwd *pw)
345 return expand_filename(options.authorized_keys_file2, pw);
348 /* return ok if key exists in sysfile or userfile */
350 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
351 const char *sysfile, const char *userfile)
356 HostStatus host_status;
358 /* Check if we know the host and its host key. */
359 found = key_new(key->type);
360 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
362 if (host_status != HOST_OK && userfile != NULL) {
363 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
364 if (options.strict_modes &&
365 (stat(user_hostfile, &st) == 0) &&
366 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
367 (st.st_mode & 022) != 0)) {
368 log("Authentication refused for %.100s: "
369 "bad owner or modes for %.200s",
370 pw->pw_name, user_hostfile);
372 temporarily_use_uid(pw);
373 host_status = check_host_in_hostfile(user_hostfile,
374 host, key, found, NULL);
377 xfree(user_hostfile);
381 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
382 "ok" : "not found", host);
388 * Check a given file for security. This is defined as all components
389 * of the path to the file must either be owned by either the owner of
390 * of the file or root and no directories must be group or world writable.
392 * XXX Should any specific check be done for sym links ?
394 * Takes an open file descriptor, the file name, a uid and and
395 * error buffer plus max size as arguments.
397 * Returns 0 on success and -1 on failure
400 secure_filename(FILE *f, const char *file, struct passwd *pw,
401 char *err, size_t errlen)
403 uid_t uid = pw->pw_uid;
404 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
408 if (realpath(file, buf) == NULL) {
409 snprintf(err, errlen, "realpath %s failed: %s", file,
413 if (realpath(pw->pw_dir, homedir) == NULL) {
414 snprintf(err, errlen, "realpath %s failed: %s", pw->pw_dir,
419 /* check the open file to avoid races */
420 if (fstat(fileno(f), &st) < 0 ||
421 (st.st_uid != 0 && st.st_uid != uid) ||
422 (st.st_mode & 022) != 0) {
423 snprintf(err, errlen, "bad ownership or modes for file %s",
428 /* for each component of the canonical path, walking upwards */
430 if ((cp = dirname(buf)) == NULL) {
431 snprintf(err, errlen, "dirname() failed");
434 strlcpy(buf, cp, sizeof(buf));
436 debug3("secure_filename: checking '%s'", buf);
437 if (stat(buf, &st) < 0 ||
438 (st.st_uid != 0 && st.st_uid != uid) ||
439 (st.st_mode & 022) != 0) {
440 snprintf(err, errlen,
441 "bad ownership or modes for directory %s", buf);
445 /* If are passed the homedir then we can stop */
446 if (strcmp(homedir, buf) == 0) {
447 debug3("secure_filename: terminating check at '%s'",
452 * dirname should always complete with a "/" path,
453 * but we can be paranoid and check for "." too
455 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
462 getpwnamallow(const char *user)
464 #ifdef HAVE_LOGIN_CAP
465 extern login_cap_t *lc;
473 if (pw == NULL || !allowed_user(pw))
475 #ifdef HAVE_LOGIN_CAP
476 if ((lc = login_getclass(pw->pw_class)) == NULL) {
477 debug("unable to get login class: %s", user);
481 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
482 auth_approval(NULL, lc, pw->pw_name, "ssh") <= 0) {
483 debug("Approval failure for %s", user);