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 1.35 2002/03/01 13:12:10 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"
53 extern ServerOptions options;
56 * Check if the user is allowed to log in via ssh. If user is listed
57 * in DenyUsers or one of user's groups is listed in DenyGroups, false
58 * will be returned. If AllowUsers isn't empty and user isn't listed
59 * there, or if AllowGroups isn't empty and one of user's groups isn't
60 * listed there, false will be returned.
61 * If the user's shell is not executable, false will be returned.
62 * Otherwise true is returned.
65 allowed_user(struct passwd * pw)
68 const char *hostname = NULL, *ipaddr = NULL;
71 #ifdef WITH_AIXAUTHENTICATE
73 #endif /* WITH_AIXAUTHENTICATE */
74 #if !defined(USE_PAM) && defined(HAVE_SHADOW_H) && \
75 !defined(DISABLE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
78 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
79 if (!pw || !pw->pw_name)
82 spw = getspnam(pw->pw_name);
84 int days = time(NULL) / 86400;
86 /* Check account expiry */
87 if ((spw->sp_expire >= 0) && (days > spw->sp_expire))
90 /* Check password expiry */
91 if ((spw->sp_lstchg >= 0) && (spw->sp_max >= 0) &&
92 (days > (spw->sp_lstchg + spw->sp_max)))
96 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
97 if (!pw || !pw->pw_name)
102 * Get the shell from the password data. An empty shell field is
103 * legal, and means /bin/sh.
105 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
107 /* deny if shell does not exists or is not executable */
108 if (stat(shell, &st) != 0) {
109 log("User %.100s not allowed because shell %.100s does not exist",
113 if (!((st.st_mode & S_IFREG) && (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)))) {
114 log("User %.100s not allowed because shell %.100s is not executable",
119 if (options.num_deny_users > 0 || options.num_allow_users > 0) {
120 hostname = get_canonical_hostname(options.verify_reverse_mapping);
121 ipaddr = get_remote_ipaddr();
124 /* Return false if user is listed in DenyUsers */
125 if (options.num_deny_users > 0) {
126 for (i = 0; i < options.num_deny_users; i++)
127 if (match_user(pw->pw_name, hostname, ipaddr,
128 options.deny_users[i])) {
129 log("User %.100s not allowed because listed in DenyUsers",
134 /* Return false if AllowUsers isn't empty and user isn't listed there */
135 if (options.num_allow_users > 0) {
136 for (i = 0; i < options.num_allow_users; i++)
137 if (match_user(pw->pw_name, hostname, ipaddr,
138 options.allow_users[i]))
140 /* i < options.num_allow_users iff we break for loop */
141 if (i >= options.num_allow_users) {
142 log("User %.100s not allowed because not listed in AllowUsers",
147 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
148 /* Get the user's group access list (primary and supplementary) */
149 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
150 log("User %.100s not allowed because not in any group",
155 /* Return false if one of user's groups is listed in DenyGroups */
156 if (options.num_deny_groups > 0)
157 if (ga_match(options.deny_groups,
158 options.num_deny_groups)) {
160 log("User %.100s not allowed because a group is listed in DenyGroups",
165 * Return false if AllowGroups isn't empty and one of user's groups
168 if (options.num_allow_groups > 0)
169 if (!ga_match(options.allow_groups,
170 options.num_allow_groups)) {
172 log("User %.100s not allowed because none of user's groups are listed in AllowGroups",
179 #ifdef WITH_AIXAUTHENTICATE
180 if (loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &loginmsg) != 0) {
181 if (loginmsg && *loginmsg) {
182 /* Remove embedded newlines (if any) */
184 for (p = loginmsg; *p; p++) {
188 /* Remove trailing newline */
190 log("Login restricted for %s: %.100s", pw->pw_name, loginmsg);
194 #endif /* WITH_AIXAUTHENTICATE */
196 /* We found no reason not to let this user try to log on... */
203 Authctxt *authctxt = xmalloc(sizeof(*authctxt));
204 memset(authctxt, 0, sizeof(*authctxt));
209 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
211 void (*authlog) (const char *fmt,...) = verbose;
214 /* Raise logging level */
215 if (authenticated == 1 ||
217 authctxt->failures >= AUTH_FAIL_LOG ||
218 strcmp(method, "password") == 0)
221 if (authctxt->postponed)
222 authmsg = "Postponed";
224 authmsg = authenticated ? "Accepted" : "Failed";
226 authlog("%s %s for %s%.100s from %.200s port %d%s",
229 authctxt->valid ? "" : "illegal user ",
237 * Check whether root logins are disallowed.
240 auth_root_allowed(char *method)
242 switch (options.permit_root_login) {
246 case PERMIT_NO_PASSWD:
247 if (strcmp(method, "password") != 0)
250 case PERMIT_FORCED_ONLY:
251 if (forced_command) {
252 log("Root login accepted for forced command.");
257 log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
263 * Given a template and a passwd structure, build a filename
264 * by substituting % tokenised options. Currently, %% becomes '%',
265 * %h becomes the home directory and %u the username.
267 * This returns a buffer allocated by xmalloc.
270 expand_filename(const char *filename, struct passwd *pw)
277 * Build the filename string in the buffer by making the appropriate
278 * substitutions to the given file name.
280 buffer_init(&buffer);
281 for (cp = filename; *cp; cp++) {
282 if (cp[0] == '%' && cp[1] == '%') {
283 buffer_append(&buffer, "%", 1);
287 if (cp[0] == '%' && cp[1] == 'h') {
288 buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
292 if (cp[0] == '%' && cp[1] == 'u') {
293 buffer_append(&buffer, pw->pw_name,
294 strlen(pw->pw_name));
298 buffer_append(&buffer, cp, 1);
300 buffer_append(&buffer, "\0", 1);
303 * Ensure that filename starts anchored. If not, be backward
304 * compatible and prepend the '%h/'
306 file = xmalloc(MAXPATHLEN);
307 cp = buffer_ptr(&buffer);
309 snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
311 strlcpy(file, cp, MAXPATHLEN);
313 buffer_free(&buffer);
318 authorized_keys_file(struct passwd *pw)
320 return expand_filename(options.authorized_keys_file, pw);
324 authorized_keys_file2(struct passwd *pw)
326 return expand_filename(options.authorized_keys_file2, pw);
329 /* return ok if key exists in sysfile or userfile */
331 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
332 const char *sysfile, const char *userfile)
337 HostStatus host_status;
339 /* Check if we know the host and its host key. */
340 found = key_new(key->type);
341 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
343 if (host_status != HOST_OK && userfile != NULL) {
344 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
345 if (options.strict_modes &&
346 (stat(user_hostfile, &st) == 0) &&
347 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
348 (st.st_mode & 022) != 0)) {
349 log("Authentication refused for %.100s: "
350 "bad owner or modes for %.200s",
351 pw->pw_name, user_hostfile);
353 temporarily_use_uid(pw);
354 host_status = check_host_in_hostfile(user_hostfile,
355 host, key, found, NULL);
358 xfree(user_hostfile);
362 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
363 "ok" : "not found", host);
369 * Check a given file for security. This is defined as all components
370 * of the path to the file must either be owned by either the owner of
371 * of the file or root and no directories must be group or world writable.
373 * XXX Should any specific check be done for sym links ?
375 * Takes an open file descriptor, the file name, a uid and and
376 * error buffer plus max size as arguments.
378 * Returns 0 on success and -1 on failure
381 secure_filename(FILE *f, const char *file, struct passwd *pw,
382 char *err, size_t errlen)
384 uid_t uid = pw->pw_uid;
385 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
389 if (realpath(file, buf) == NULL) {
390 snprintf(err, errlen, "realpath %s failed: %s", file,
394 if (realpath(pw->pw_dir, homedir) == NULL) {
395 snprintf(err, errlen, "realpath %s failed: %s", pw->pw_dir,
400 /* check the open file to avoid races */
401 if (fstat(fileno(f), &st) < 0 ||
402 (st.st_uid != 0 && st.st_uid != uid) ||
403 (st.st_mode & 022) != 0) {
404 snprintf(err, errlen, "bad ownership or modes for file %s",
409 /* for each component of the canonical path, walking upwards */
411 if ((cp = dirname(buf)) == NULL) {
412 snprintf(err, errlen, "dirname() failed");
415 strlcpy(buf, cp, sizeof(buf));
417 debug3("secure_filename: checking '%s'", buf);
418 if (stat(buf, &st) < 0 ||
419 (st.st_uid != 0 && st.st_uid != uid) ||
420 (st.st_mode & 022) != 0) {
421 snprintf(err, errlen,
422 "bad ownership or modes for directory %s", buf);
426 /* If are passed the homedir then we can stop */
427 if (strcmp(homedir, buf) == 0) {
428 debug3("secure_filename: terminating check at '%s'",
433 * dirname should always complete with a "/" path,
434 * but we can be paranoid and check for "." too
436 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))