1 /* $OpenBSD: auth.c,v 1.80 2008/11/04 07:58:09 djm 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 #include "ssh-globus-usage.h"
78 extern ServerOptions options;
79 extern int use_privsep;
80 extern Buffer loginmsg;
81 extern struct passwd *privsep_pw;
83 /* Debugging messages */
88 * Check if the user is allowed to log in via ssh. If user is listed
89 * in DenyUsers or one of user's groups is listed in DenyGroups, false
90 * will be returned. If AllowUsers isn't empty and user isn't listed
91 * there, or if AllowGroups isn't empty and one of user's groups isn't
92 * listed there, false will be returned.
93 * If the user's shell is not executable, false will be returned.
94 * Otherwise true is returned.
97 allowed_user(struct passwd * pw)
100 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
104 struct spwd *spw = NULL;
107 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
108 if (!pw || !pw->pw_name)
112 if (!options.use_pam)
113 spw = getspnam(pw->pw_name);
114 #ifdef HAS_SHADOW_EXPIRE
115 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
117 #endif /* HAS_SHADOW_EXPIRE */
118 #endif /* USE_SHADOW */
120 /* grab passwd field for locked account check */
121 passwd = pw->pw_passwd;
125 passwd = get_iaf_password(pw);
127 passwd = spw->sp_pwdp;
128 #endif /* USE_LIBIAF */
131 /* check for locked account */
132 if (!options.use_pam && passwd && *passwd) {
135 #ifdef LOCKED_PASSWD_STRING
136 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
139 #ifdef LOCKED_PASSWD_PREFIX
140 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
141 strlen(LOCKED_PASSWD_PREFIX)) == 0)
144 #ifdef LOCKED_PASSWD_SUBSTR
145 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
150 #endif /* USE_LIBIAF */
152 logit("User %.100s not allowed because account is locked",
159 * Get the shell from the password data. An empty shell field is
160 * legal, and means /bin/sh.
162 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
164 /* deny if shell does not exists or is not executable */
165 if (stat(shell, &st) != 0) {
166 logit("User %.100s not allowed because shell %.100s does not exist",
170 if (S_ISREG(st.st_mode) == 0 ||
171 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
172 logit("User %.100s not allowed because shell %.100s is not executable",
177 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
178 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
179 hostname = get_canonical_hostname(options.use_dns);
180 ipaddr = get_remote_ipaddr();
183 /* Return false if user is listed in DenyUsers */
184 if (options.num_deny_users > 0) {
185 for (i = 0; i < options.num_deny_users; i++)
186 if (match_user(pw->pw_name, hostname, ipaddr,
187 options.deny_users[i])) {
188 logit("User %.100s from %.100s not allowed "
189 "because listed in DenyUsers",
190 pw->pw_name, hostname);
194 /* Return false if AllowUsers isn't empty and user isn't listed there */
195 if (options.num_allow_users > 0) {
196 for (i = 0; i < options.num_allow_users; i++)
197 if (match_user(pw->pw_name, hostname, ipaddr,
198 options.allow_users[i]))
200 /* i < options.num_allow_users iff we break for loop */
201 if (i >= options.num_allow_users) {
202 logit("User %.100s from %.100s not allowed because "
203 "not listed in AllowUsers", pw->pw_name, hostname);
207 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
208 /* Get the user's group access list (primary and supplementary) */
209 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
210 logit("User %.100s from %.100s not allowed because "
211 "not in any group", pw->pw_name, hostname);
215 /* Return false if one of user's groups is listed in DenyGroups */
216 if (options.num_deny_groups > 0)
217 if (ga_match(options.deny_groups,
218 options.num_deny_groups)) {
220 logit("User %.100s from %.100s not allowed "
221 "because a group is listed in DenyGroups",
222 pw->pw_name, hostname);
226 * Return false if AllowGroups isn't empty and one of user's groups
229 if (options.num_allow_groups > 0)
230 if (!ga_match(options.allow_groups,
231 options.num_allow_groups)) {
233 logit("User %.100s from %.100s not allowed "
234 "because none of user's groups are listed "
235 "in AllowGroups", pw->pw_name, hostname);
241 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
242 if (!sys_auth_allowed_user(pw, &loginmsg))
246 /* We found no reason not to let this user try to log on... */
251 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
253 void (*authlog) (const char *fmt,...) = verbose;
256 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
259 /* Raise logging level */
260 if (authenticated == 1 ||
262 authctxt->failures >= options.max_authtries / 2 ||
263 strcmp(method, "password") == 0)
266 if (authctxt->postponed)
267 authmsg = "Postponed";
269 authmsg = authenticated ? "Accepted" : "Failed";
271 authlog("%s %s for %s%.100s from %.200s port %d%s",
274 authctxt->valid ? "" : "invalid user ",
275 (authctxt->user && authctxt->user[0]) ?
276 authctxt->user : "unknown",
281 #ifdef CUSTOM_FAILED_LOGIN
282 if (authenticated == 0 && !authctxt->postponed &&
283 (strcmp(method, "password") == 0 ||
284 strncmp(method, "keyboard-interactive", 20) == 0 ||
285 strcmp(method, "challenge-response") == 0))
286 record_failed_login(authctxt->user,
287 get_canonical_hostname(options.use_dns), "ssh");
288 # ifdef WITH_AIXAUTHENTICATE
290 sys_auth_record_login(authctxt->user,
291 get_canonical_hostname(options.use_dns), "ssh", &loginmsg);
294 #ifdef SSH_AUDIT_EVENTS
295 if (authenticated == 0 && !authctxt->postponed)
296 audit_event(audit_classify_auth(method));
300 char *mech_name = NULL;
301 ssh_gssapi_get_client_info(&userdn, &mech_name);
302 debug("REPORTING (%s) (%s) (%s) (%s) (%s) (%s) (%s)",
303 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION),
304 method, mech_name?mech_name:"NULL", get_remote_ipaddr(),
305 (authctxt->user && authctxt->user[0])?
306 authctxt->user : "unknown",
307 userdn?userdn:"NULL");
308 ssh_globus_send_usage_metrics(SSH_RELEASE,
309 SSLeay_version(SSLEAY_VERSION),
310 method, mech_name, get_remote_ipaddr(),
311 authctxt->user, userdn);
316 * Check whether root logins are disallowed.
319 auth_root_allowed(char *method)
321 switch (options.permit_root_login) {
324 case PERMIT_NO_PASSWD:
325 if (strcmp(method, "password") != 0)
328 case PERMIT_FORCED_ONLY:
329 if (forced_command) {
330 logit("Root login accepted for forced command.");
335 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
341 * Given a template and a passwd structure, build a filename
342 * by substituting % tokenised options. Currently, %% becomes '%',
343 * %h becomes the home directory and %u the username.
345 * This returns a buffer allocated by xmalloc.
348 expand_authorized_keys(const char *filename, struct passwd *pw)
350 char *file, ret[MAXPATHLEN];
353 file = percent_expand(filename, "h", pw->pw_dir,
354 "u", pw->pw_name, (char *)NULL);
357 * Ensure that filename starts anchored. If not, be backward
358 * compatible and prepend the '%h/'
363 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
364 if (i < 0 || (size_t)i >= sizeof(ret))
365 fatal("expand_authorized_keys: path too long");
367 return (xstrdup(ret));
371 authorized_keys_file(struct passwd *pw)
373 return expand_authorized_keys(options.authorized_keys_file, pw);
377 authorized_keys_file2(struct passwd *pw)
379 return expand_authorized_keys(options.authorized_keys_file2, pw);
382 /* return ok if key exists in sysfile or userfile */
384 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
385 const char *sysfile, const char *userfile)
390 HostStatus host_status;
392 /* Check if we know the host and its host key. */
393 found = key_new(key->type);
394 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
396 if (host_status != HOST_OK && userfile != NULL) {
397 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
398 if (options.strict_modes &&
399 (stat(user_hostfile, &st) == 0) &&
400 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
401 (st.st_mode & 022) != 0)) {
402 logit("Authentication refused for %.100s: "
403 "bad owner or modes for %.200s",
404 pw->pw_name, user_hostfile);
406 temporarily_use_uid(pw);
407 host_status = check_host_in_hostfile(user_hostfile,
408 host, key, found, NULL);
411 xfree(user_hostfile);
415 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
416 "ok" : "not found", host);
422 * Check a given file for security. This is defined as all components
423 * of the path to the file must be owned by either the owner of
424 * of the file or root and no directories must be group or world writable.
426 * XXX Should any specific check be done for sym links ?
428 * Takes an open file descriptor, the file name, a uid and and
429 * error buffer plus max size as arguments.
431 * Returns 0 on success and -1 on failure
434 secure_filename(FILE *f, const char *file, struct passwd *pw,
435 char *err, size_t errlen)
437 uid_t uid = pw->pw_uid;
438 char buf[MAXPATHLEN], homedir[MAXPATHLEN];
443 if (realpath(file, buf) == NULL) {
444 snprintf(err, errlen, "realpath %s failed: %s", file,
448 if (realpath(pw->pw_dir, homedir) != NULL)
451 /* check the open file to avoid races */
452 if (fstat(fileno(f), &st) < 0 ||
453 (st.st_uid != 0 && st.st_uid != uid) ||
454 (st.st_mode & 022) != 0) {
455 snprintf(err, errlen, "bad ownership or modes for file %s",
460 /* for each component of the canonical path, walking upwards */
462 if ((cp = dirname(buf)) == NULL) {
463 snprintf(err, errlen, "dirname() failed");
466 strlcpy(buf, cp, sizeof(buf));
468 debug3("secure_filename: checking '%s'", buf);
469 if (stat(buf, &st) < 0 ||
470 (st.st_uid != 0 && st.st_uid != uid) ||
471 (st.st_mode & 022) != 0) {
472 snprintf(err, errlen,
473 "bad ownership or modes for directory %s", buf);
477 /* If are passed the homedir then we can stop */
478 if (comparehome && strcmp(homedir, buf) == 0) {
479 debug3("secure_filename: terminating check at '%s'",
484 * dirname should always complete with a "/" path,
485 * but we can be paranoid and check for "." too
487 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
494 auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
502 * Open the file containing the authorized keys
503 * Fail quietly if file does not exist
505 if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1)
508 if (fstat(fd, &st) < 0) {
512 if (!S_ISREG(st.st_mode)) {
513 logit("User %s authorized keys %s is not a regular file",
519 if ((f = fdopen(fd, "r")) == NULL) {
523 if (options.strict_modes &&
524 secure_filename(f, file, pw, line, sizeof(line)) != 0) {
526 logit("Authentication refused: %s", line);
534 getpwnamallow(const char *user)
536 #ifdef HAVE_LOGIN_CAP
537 extern login_cap_t *lc;
544 parse_server_match_config(&options, user,
545 get_canonical_hostname(options.use_dns), get_remote_ipaddr());
549 if (options.use_pam && options.permit_pam_user_change && pw == NULL)
550 pw = sshpam_getpw(user);
553 logit("Invalid user %.100s from %.100s",
554 (user && user[0]) ? user : "unknown",
555 get_remote_ipaddr());
556 #ifdef CUSTOM_FAILED_LOGIN
557 record_failed_login(user,
558 get_canonical_hostname(options.use_dns), "ssh");
560 #ifdef SSH_AUDIT_EVENTS
561 audit_event(SSH_INVALID_USER);
562 #endif /* SSH_AUDIT_EVENTS */
565 if (!allowed_user(pw))
567 #ifdef HAVE_LOGIN_CAP
568 if ((lc = login_getclass(pw->pw_class)) == NULL) {
569 debug("unable to get login class: %s", user);
573 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
574 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
575 debug("Approval failure for %s", user);
588 auth_debug_add(const char *fmt,...)
593 if (!auth_debug_init)
597 vsnprintf(buf, sizeof(buf), fmt, args);
599 buffer_put_cstring(&auth_debug, buf);
603 auth_debug_send(void)
607 if (!auth_debug_init)
609 while (buffer_len(&auth_debug)) {
610 msg = buffer_get_string(&auth_debug, NULL);
611 packet_send_debug("%s", msg);
617 auth_debug_reset(void)
620 buffer_clear(&auth_debug);
622 buffer_init(&auth_debug);
630 static struct passwd fake;
632 memset(&fake, 0, sizeof(fake));
633 fake.pw_name = "NOUSER";
635 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
636 fake.pw_gecos = "NOUSER";
637 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
638 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
639 #ifdef HAVE_PW_CLASS_IN_PASSWD
642 fake.pw_dir = "/nonexist";
643 fake.pw_shell = "/nonexist";