1 /* $OpenBSD: auth.c,v 1.79 2008/07/02 12:03:51 dtucker 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>
56 #include "groupaccess.h"
63 #include "auth-options.h"
72 #include "monitor_wrap.h"
75 extern ServerOptions options;
76 extern int use_privsep;
77 extern Buffer loginmsg;
78 extern struct passwd *privsep_pw;
80 /* Debugging messages */
85 * Check if the user is allowed to log in via ssh. If user is listed
86 * in DenyUsers or one of user's groups is listed in DenyGroups, false
87 * will be returned. If AllowUsers isn't empty and user isn't listed
88 * there, or if AllowGroups isn't empty and one of user's groups isn't
89 * listed there, false will be returned.
90 * If the user's shell is not executable, false will be returned.
91 * Otherwise true is returned.
94 allowed_user(struct passwd * pw)
97 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
101 struct spwd *spw = NULL;
104 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
105 if (!pw || !pw->pw_name)
109 if (!options.use_pam)
110 spw = getspnam(pw->pw_name);
111 #ifdef HAS_SHADOW_EXPIRE
112 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
114 #endif /* HAS_SHADOW_EXPIRE */
115 #endif /* USE_SHADOW */
117 /* grab passwd field for locked account check */
118 passwd = pw->pw_passwd;
122 passwd = get_iaf_password(pw);
124 passwd = spw->sp_pwdp;
125 #endif /* USE_LIBIAF */
128 /* check for locked account */
129 if (!options.use_pam && passwd && *passwd) {
132 #ifdef LOCKED_PASSWD_STRING
133 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
136 #ifdef LOCKED_PASSWD_PREFIX
137 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
138 strlen(LOCKED_PASSWD_PREFIX)) == 0)
141 #ifdef LOCKED_PASSWD_SUBSTR
142 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
147 #endif /* USE_LIBIAF */
149 logit("User %.100s not allowed because account is locked",
156 * Get the shell from the password data. An empty shell field is
157 * legal, and means /bin/sh.
159 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
161 /* deny if shell does not exists or is not executable */
162 if (stat(shell, &st) != 0) {
163 logit("User %.100s not allowed because shell %.100s does not exist",
167 if (S_ISREG(st.st_mode) == 0 ||
168 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
169 logit("User %.100s not allowed because shell %.100s is not executable",
174 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
175 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
176 hostname = get_canonical_hostname(options.use_dns);
177 ipaddr = get_remote_ipaddr();
180 /* Return false if user is listed in DenyUsers */
181 if (options.num_deny_users > 0) {
182 for (i = 0; i < options.num_deny_users; i++)
183 if (match_user(pw->pw_name, hostname, ipaddr,
184 options.deny_users[i])) {
185 logit("User %.100s from %.100s not allowed "
186 "because listed in DenyUsers",
187 pw->pw_name, hostname);
191 /* Return false if AllowUsers isn't empty and user isn't listed there */
192 if (options.num_allow_users > 0) {
193 for (i = 0; i < options.num_allow_users; i++)
194 if (match_user(pw->pw_name, hostname, ipaddr,
195 options.allow_users[i]))
197 /* i < options.num_allow_users iff we break for loop */
198 if (i >= options.num_allow_users) {
199 logit("User %.100s from %.100s not allowed because "
200 "not listed in AllowUsers", pw->pw_name, hostname);
204 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
205 /* Get the user's group access list (primary and supplementary) */
206 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
207 logit("User %.100s from %.100s not allowed because "
208 "not in any group", pw->pw_name, hostname);
212 /* Return false if one of user's groups is listed in DenyGroups */
213 if (options.num_deny_groups > 0)
214 if (ga_match(options.deny_groups,
215 options.num_deny_groups)) {
217 logit("User %.100s from %.100s not allowed "
218 "because a group is listed in DenyGroups",
219 pw->pw_name, hostname);
223 * Return false if AllowGroups isn't empty and one of user's groups
226 if (options.num_allow_groups > 0)
227 if (!ga_match(options.allow_groups,
228 options.num_allow_groups)) {
230 logit("User %.100s from %.100s not allowed "
231 "because none of user's groups are listed "
232 "in AllowGroups", pw->pw_name, hostname);
238 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
239 if (!sys_auth_allowed_user(pw, &loginmsg))
243 /* We found no reason not to let this user try to log on... */
248 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
250 void (*authlog) (const char *fmt,...) = verbose;
253 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
256 /* Raise logging level */
257 if (authenticated == 1 ||
259 authctxt->failures >= options.max_authtries / 2 ||
260 strcmp(method, "password") == 0)
263 if (authctxt->postponed)
264 authmsg = "Postponed";
266 authmsg = authenticated ? "Accepted" : "Failed";
268 authlog("%s %s for %s%.100s from %.200s port %d%s",
271 authctxt->valid ? "" : "invalid user ",
277 #ifdef CUSTOM_FAILED_LOGIN
278 if (authenticated == 0 && !authctxt->postponed &&
279 (strcmp(method, "password") == 0 ||
280 strncmp(method, "keyboard-interactive", 20) == 0 ||
281 strcmp(method, "challenge-response") == 0))
282 record_failed_login(authctxt->user,
283 get_canonical_hostname(options.use_dns), "ssh");
284 # ifdef WITH_AIXAUTHENTICATE
286 sys_auth_record_login(authctxt->user,
287 get_canonical_hostname(options.use_dns), "ssh", &loginmsg);
290 #ifdef SSH_AUDIT_EVENTS
291 if (authenticated == 0 && !authctxt->postponed)
292 audit_event(audit_classify_auth(method));
297 * Check whether root logins are disallowed.
300 auth_root_allowed(char *method)
302 switch (options.permit_root_login) {
305 case PERMIT_NO_PASSWD:
306 if (strcmp(method, "password") != 0)
309 case PERMIT_FORCED_ONLY:
310 if (forced_command) {
311 logit("Root login accepted for forced command.");
316 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
322 * Given a template and a passwd structure, build a filename
323 * by substituting % tokenised options. Currently, %% becomes '%',
324 * %h becomes the home directory and %u the username.
326 * This returns a buffer allocated by xmalloc.
329 expand_authorized_keys(const char *filename, struct passwd *pw)
331 char *file, ret[MAXPATHLEN];
334 file = percent_expand(filename, "h", pw->pw_dir,
335 "u", pw->pw_name, (char *)NULL);
338 * Ensure that filename starts anchored. If not, be backward
339 * compatible and prepend the '%h/'
344 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
345 if (i < 0 || (size_t)i >= sizeof(ret))
346 fatal("expand_authorized_keys: path too long");
348 return (xstrdup(ret));
352 authorized_keys_file(struct passwd *pw)
354 return expand_authorized_keys(options.authorized_keys_file, pw);
358 authorized_keys_file2(struct passwd *pw)
360 return expand_authorized_keys(options.authorized_keys_file2, pw);
363 /* return ok if key exists in sysfile or userfile */
365 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
366 const char *sysfile, const char *userfile)
371 HostStatus host_status;
373 /* Check if we know the host and its host key. */
374 found = key_new(key->type);
375 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
377 if (host_status != HOST_OK && userfile != NULL) {
378 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
379 if (options.strict_modes &&
380 (stat(user_hostfile, &st) == 0) &&
381 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
382 (st.st_mode & 022) != 0)) {
383 logit("Authentication refused for %.100s: "
384 "bad owner or modes for %.200s",
385 pw->pw_name, user_hostfile);
387 temporarily_use_uid(pw);
388 host_status = check_host_in_hostfile(user_hostfile,
389 host, key, found, NULL);
392 xfree(user_hostfile);
396 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
397 "ok" : "not found", host);
403 * Check a given file for security. This is defined as all components
404 * of the path to the file must be owned by either the owner of
405 * of the file or root and no directories must be group or world writable.
407 * XXX Should any specific check be done for sym links ?
409 * Takes an open file descriptor, the file name, a uid and and
410 * error buffer plus max size as arguments.
412 * Returns 0 on success and -1 on failure
415 secure_filename(FILE *f, const char *file, struct passwd *pw,
416 char *err, size_t errlen)
418 uid_t uid = pw->pw_uid;
419 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
424 if (realpath(file, buf) == NULL) {
425 snprintf(err, errlen, "realpath %s failed: %s", file,
429 if (realpath(pw->pw_dir, homedir) != NULL)
432 /* check the open file to avoid races */
433 if (fstat(fileno(f), &st) < 0 ||
434 (st.st_uid != 0 && st.st_uid != uid) ||
435 (st.st_mode & 022) != 0) {
436 snprintf(err, errlen, "bad ownership or modes for file %s",
441 /* for each component of the canonical path, walking upwards */
443 if ((cp = dirname(buf)) == NULL) {
444 snprintf(err, errlen, "dirname() failed");
447 strlcpy(buf, cp, sizeof(buf));
449 debug3("secure_filename: checking '%s'", buf);
450 if (stat(buf, &st) < 0 ||
451 (st.st_uid != 0 && st.st_uid != uid) ||
452 (st.st_mode & 022) != 0) {
453 snprintf(err, errlen,
454 "bad ownership or modes for directory %s", buf);
458 /* If are passed the homedir then we can stop */
459 if (comparehome && strcmp(homedir, buf) == 0) {
460 debug3("secure_filename: terminating check at '%s'",
465 * dirname should always complete with a "/" path,
466 * but we can be paranoid and check for "." too
468 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
475 auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
483 * Open the file containing the authorized keys
484 * Fail quietly if file does not exist
486 if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1)
489 if (fstat(fd, &st) < 0) {
493 if (!S_ISREG(st.st_mode)) {
494 logit("User %s authorized keys %s is not a regular file",
500 if ((f = fdopen(fd, "r")) == NULL) {
504 if (options.strict_modes &&
505 secure_filename(f, file, pw, line, sizeof(line)) != 0) {
507 logit("Authentication refused: %s", line);
515 getpwnamallow(const char *user)
517 #ifdef HAVE_LOGIN_CAP
518 extern login_cap_t *lc;
525 parse_server_match_config(&options, user,
526 get_canonical_hostname(options.use_dns), get_remote_ipaddr());
530 logit("Invalid user %.100s from %.100s",
531 user, get_remote_ipaddr());
532 #ifdef CUSTOM_FAILED_LOGIN
533 record_failed_login(user,
534 get_canonical_hostname(options.use_dns), "ssh");
536 #ifdef SSH_AUDIT_EVENTS
537 audit_event(SSH_INVALID_USER);
538 #endif /* SSH_AUDIT_EVENTS */
541 if (!allowed_user(pw))
543 #ifdef HAVE_LOGIN_CAP
544 if ((lc = login_getclass(pw->pw_class)) == NULL) {
545 debug("unable to get login class: %s", user);
549 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
550 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
551 debug("Approval failure for %s", user);
564 auth_debug_add(const char *fmt,...)
569 if (!auth_debug_init)
573 vsnprintf(buf, sizeof(buf), fmt, args);
575 buffer_put_cstring(&auth_debug, buf);
579 auth_debug_send(void)
583 if (!auth_debug_init)
585 while (buffer_len(&auth_debug)) {
586 msg = buffer_get_string(&auth_debug, NULL);
587 packet_send_debug("%s", msg);
593 auth_debug_reset(void)
596 buffer_clear(&auth_debug);
598 buffer_init(&auth_debug);
606 static struct passwd fake;
608 memset(&fake, 0, sizeof(fake));
609 fake.pw_name = "NOUSER";
611 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
612 fake.pw_gecos = "NOUSER";
613 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
614 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
615 #ifdef HAVE_PW_CLASS_IN_PASSWD
618 fake.pw_dir = "/nonexist";
619 fake.pw_shell = "/nonexist";