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 1.40 2002/03/19 14:27:39 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 spw = getspnam(pw->pw_name);
85 int days = time(NULL) / 86400;
87 /* Check account expiry */
88 if ((spw->sp_expire >= 0) && (days > spw->sp_expire))
91 /* Check password expiry */
92 if ((spw->sp_lstchg >= 0) && (spw->sp_max >= 0) &&
93 (days > (spw->sp_lstchg + spw->sp_max)))
97 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
98 if (!pw || !pw->pw_name)
103 * Get the shell from the password data. An empty shell field is
104 * legal, and means /bin/sh.
106 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
108 /* deny if shell does not exists or is not executable */
109 if (stat(shell, &st) != 0) {
110 log("User %.100s not allowed because shell %.100s does not exist",
114 if (S_ISREG(st.st_mode) == 0 ||
115 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
116 log("User %.100s not allowed because shell %.100s is not executable",
121 if (options.num_deny_users > 0 || options.num_allow_users > 0) {
122 hostname = get_canonical_hostname(options.verify_reverse_mapping);
123 ipaddr = get_remote_ipaddr();
126 /* Return false if user is listed in DenyUsers */
127 if (options.num_deny_users > 0) {
128 for (i = 0; i < options.num_deny_users; i++)
129 if (match_user(pw->pw_name, hostname, ipaddr,
130 options.deny_users[i])) {
131 log("User %.100s not allowed because listed in DenyUsers",
136 /* Return false if AllowUsers isn't empty and user isn't listed there */
137 if (options.num_allow_users > 0) {
138 for (i = 0; i < options.num_allow_users; i++)
139 if (match_user(pw->pw_name, hostname, ipaddr,
140 options.allow_users[i]))
142 /* i < options.num_allow_users iff we break for loop */
143 if (i >= options.num_allow_users) {
144 log("User %.100s not allowed because not listed in AllowUsers",
149 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
150 /* Get the user's group access list (primary and supplementary) */
151 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
152 log("User %.100s not allowed because not in any group",
157 /* Return false if one of user's groups is listed in DenyGroups */
158 if (options.num_deny_groups > 0)
159 if (ga_match(options.deny_groups,
160 options.num_deny_groups)) {
162 log("User %.100s not allowed because a group is listed in DenyGroups",
167 * Return false if AllowGroups isn't empty and one of user's groups
170 if (options.num_allow_groups > 0)
171 if (!ga_match(options.allow_groups,
172 options.num_allow_groups)) {
174 log("User %.100s not allowed because none of user's groups are listed in AllowGroups",
181 #ifdef WITH_AIXAUTHENTICATE
182 if (loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &loginmsg) != 0) {
183 if (loginmsg && *loginmsg) {
184 /* Remove embedded newlines (if any) */
186 for (p = loginmsg; *p; p++) {
190 /* Remove trailing newline */
192 log("Login restricted for %s: %.100s", pw->pw_name, loginmsg);
196 #endif /* WITH_AIXAUTHENTICATE */
198 /* We found no reason not to let this user try to log on... */
205 Authctxt *authctxt = xmalloc(sizeof(*authctxt));
206 memset(authctxt, 0, sizeof(*authctxt));
211 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
213 void (*authlog) (const char *fmt,...) = verbose;
216 /* Raise logging level */
217 if (authenticated == 1 ||
219 authctxt->failures >= AUTH_FAIL_LOG ||
220 strcmp(method, "password") == 0)
223 if (authctxt->postponed)
224 authmsg = "Postponed";
226 authmsg = authenticated ? "Accepted" : "Failed";
228 authlog("%s %s for %s%.100s from %.200s port %d%s",
231 authctxt->valid ? "" : "illegal user ",
239 * Check whether root logins are disallowed.
242 auth_root_allowed(char *method)
244 switch (options.permit_root_login) {
248 case PERMIT_NO_PASSWD:
249 if (strcmp(method, "password") != 0)
252 case PERMIT_FORCED_ONLY:
253 if (forced_command) {
254 log("Root login accepted for forced command.");
259 log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
265 * Given a template and a passwd structure, build a filename
266 * by substituting % tokenised options. Currently, %% becomes '%',
267 * %h becomes the home directory and %u the username.
269 * This returns a buffer allocated by xmalloc.
272 expand_filename(const char *filename, struct passwd *pw)
279 * Build the filename string in the buffer by making the appropriate
280 * substitutions to the given file name.
282 buffer_init(&buffer);
283 for (cp = filename; *cp; cp++) {
284 if (cp[0] == '%' && cp[1] == '%') {
285 buffer_append(&buffer, "%", 1);
289 if (cp[0] == '%' && cp[1] == 'h') {
290 buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
294 if (cp[0] == '%' && cp[1] == 'u') {
295 buffer_append(&buffer, pw->pw_name,
296 strlen(pw->pw_name));
300 buffer_append(&buffer, cp, 1);
302 buffer_append(&buffer, "\0", 1);
305 * Ensure that filename starts anchored. If not, be backward
306 * compatible and prepend the '%h/'
308 file = xmalloc(MAXPATHLEN);
309 cp = buffer_ptr(&buffer);
311 snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
313 strlcpy(file, cp, MAXPATHLEN);
315 buffer_free(&buffer);
320 authorized_keys_file(struct passwd *pw)
322 return expand_filename(options.authorized_keys_file, pw);
326 authorized_keys_file2(struct passwd *pw)
328 return expand_filename(options.authorized_keys_file2, pw);
331 /* return ok if key exists in sysfile or userfile */
333 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
334 const char *sysfile, const char *userfile)
339 HostStatus host_status;
341 /* Check if we know the host and its host key. */
342 found = key_new(key->type);
343 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
345 if (host_status != HOST_OK && userfile != NULL) {
346 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
347 if (options.strict_modes &&
348 (stat(user_hostfile, &st) == 0) &&
349 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
350 (st.st_mode & 022) != 0)) {
351 log("Authentication refused for %.100s: "
352 "bad owner or modes for %.200s",
353 pw->pw_name, user_hostfile);
355 temporarily_use_uid(pw);
356 host_status = check_host_in_hostfile(user_hostfile,
357 host, key, found, NULL);
360 xfree(user_hostfile);
364 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
365 "ok" : "not found", host);
371 * Check a given file for security. This is defined as all components
372 * of the path to the file must either be owned by either the owner of
373 * of the file or root and no directories must be group or world writable.
375 * XXX Should any specific check be done for sym links ?
377 * Takes an open file descriptor, the file name, a uid and and
378 * error buffer plus max size as arguments.
380 * Returns 0 on success and -1 on failure
383 secure_filename(FILE *f, const char *file, struct passwd *pw,
384 char *err, size_t errlen)
386 uid_t uid = pw->pw_uid;
387 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
391 if (realpath(file, buf) == NULL) {
392 snprintf(err, errlen, "realpath %s failed: %s", file,
396 if (realpath(pw->pw_dir, homedir) == NULL) {
397 snprintf(err, errlen, "realpath %s failed: %s", pw->pw_dir,
402 /* check the open file to avoid races */
403 if (fstat(fileno(f), &st) < 0 ||
404 (st.st_uid != 0 && st.st_uid != uid) ||
405 (st.st_mode & 022) != 0) {
406 snprintf(err, errlen, "bad ownership or modes for file %s",
411 /* for each component of the canonical path, walking upwards */
413 if ((cp = dirname(buf)) == NULL) {
414 snprintf(err, errlen, "dirname() failed");
417 strlcpy(buf, cp, sizeof(buf));
419 debug3("secure_filename: checking '%s'", buf);
420 if (stat(buf, &st) < 0 ||
421 (st.st_uid != 0 && st.st_uid != uid) ||
422 (st.st_mode & 022) != 0) {
423 snprintf(err, errlen,
424 "bad ownership or modes for directory %s", buf);
428 /* If are passed the homedir then we can stop */
429 if (strcmp(homedir, buf) == 0) {
430 debug3("secure_filename: terminating check at '%s'",
435 * dirname should always complete with a "/" path,
436 * but we can be paranoid and check for "." too
438 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
445 getpwnamallow(const char *user)
447 #ifdef HAVE_LOGIN_CAP
448 extern login_cap_t *lc;
456 if (pw == NULL || !allowed_user(pw))
458 #ifdef HAVE_LOGIN_CAP
459 if ((lc = login_getclass(pw->pw_class)) == NULL) {
460 debug("unable to get login class: %s", user);
464 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
465 auth_approval(NULL, lc, pw->pw_name, "ssh") <= 0) {
466 debug("Approval failure for %s", user);