1 /* $OpenBSD: auth.c,v 1.86 2010/03/05 02:58:11 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"
73 #include "monitor_wrap.h"
76 extern ServerOptions options
;
77 extern int use_privsep
;
78 extern Buffer loginmsg
;
79 extern struct passwd
*privsep_pw
;
81 /* Debugging messages */
86 * Check if the user is allowed to log in via ssh. If user is listed
87 * in DenyUsers or one of user's groups is listed in DenyGroups, false
88 * will be returned. If AllowUsers isn't empty and user isn't listed
89 * there, or if AllowGroups isn't empty and one of user's groups isn't
90 * listed there, false will be returned.
91 * If the user's shell is not executable, false will be returned.
92 * Otherwise true is returned.
95 allowed_user(struct passwd
* pw
)
98 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 * Deny if shell does not exist or is not executable unless we
159 if (options
.chroot_directory
== NULL
||
160 strcasecmp(options
.chroot_directory
, "none") == 0) {
161 char *shell
= xstrdup((pw
->pw_shell
[0] == '\0') ?
162 _PATH_BSHELL
: pw
->pw_shell
); /* empty = /bin/sh */
164 if (stat(shell
, &st
) != 0) {
165 logit("User %.100s not allowed because shell %.100s "
166 "does not exist", pw
->pw_name
, shell
);
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 "
173 "is not executable", pw
->pw_name
, shell
);
180 if (options
.num_deny_users
> 0 || options
.num_allow_users
> 0 ||
181 options
.num_deny_groups
> 0 || options
.num_allow_groups
> 0) {
182 hostname
= get_canonical_hostname(options
.use_dns
);
183 ipaddr
= get_remote_ipaddr();
186 /* Return false if user is listed in DenyUsers */
187 if (options
.num_deny_users
> 0) {
188 for (i
= 0; i
< options
.num_deny_users
; i
++)
189 if (match_user(pw
->pw_name
, hostname
, ipaddr
,
190 options
.deny_users
[i
])) {
191 logit("User %.100s from %.100s not allowed "
192 "because listed in DenyUsers",
193 pw
->pw_name
, hostname
);
197 /* Return false if AllowUsers isn't empty and user isn't listed there */
198 if (options
.num_allow_users
> 0) {
199 for (i
= 0; i
< options
.num_allow_users
; i
++)
200 if (match_user(pw
->pw_name
, hostname
, ipaddr
,
201 options
.allow_users
[i
]))
203 /* i < options.num_allow_users iff we break for loop */
204 if (i
>= options
.num_allow_users
) {
205 logit("User %.100s from %.100s not allowed because "
206 "not listed in AllowUsers", pw
->pw_name
, hostname
);
210 if (options
.num_deny_groups
> 0 || options
.num_allow_groups
> 0) {
211 /* Get the user's group access list (primary and supplementary) */
212 if (ga_init(pw
->pw_name
, pw
->pw_gid
) == 0) {
213 logit("User %.100s from %.100s not allowed because "
214 "not in any group", pw
->pw_name
, hostname
);
218 /* Return false if one of user's groups is listed in DenyGroups */
219 if (options
.num_deny_groups
> 0)
220 if (ga_match(options
.deny_groups
,
221 options
.num_deny_groups
)) {
223 logit("User %.100s from %.100s not allowed "
224 "because a group is listed in DenyGroups",
225 pw
->pw_name
, hostname
);
229 * Return false if AllowGroups isn't empty and one of user's groups
232 if (options
.num_allow_groups
> 0)
233 if (!ga_match(options
.allow_groups
,
234 options
.num_allow_groups
)) {
236 logit("User %.100s from %.100s not allowed "
237 "because none of user's groups are listed "
238 "in AllowGroups", pw
->pw_name
, hostname
);
244 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
245 if (!sys_auth_allowed_user(pw
, &loginmsg
))
249 /* We found no reason not to let this user try to log on... */
254 auth_log(Authctxt
*authctxt
, int authenticated
, char *method
, char *info
)
256 void (*authlog
) (const char *fmt
,...) = verbose
;
259 if (use_privsep
&& !mm_is_monitor() && !authctxt
->postponed
)
262 /* Raise logging level */
263 if (authenticated
== 1 ||
265 authctxt
->failures
>= options
.max_authtries
/ 2 ||
266 strcmp(method
, "password") == 0)
269 if (authctxt
->postponed
)
270 authmsg
= "Postponed";
272 authmsg
= authenticated
? "Accepted" : "Failed";
274 authlog("%s %s for %s%.100s from %.200s port %d%s",
277 authctxt
->valid
? "" : "invalid user ",
283 #ifdef CUSTOM_FAILED_LOGIN
284 if (authenticated
== 0 && !authctxt
->postponed
&&
285 (strcmp(method
, "password") == 0 ||
286 strncmp(method
, "keyboard-interactive", 20) == 0 ||
287 strcmp(method
, "challenge-response") == 0))
288 record_failed_login(authctxt
->user
,
289 get_canonical_hostname(options
.use_dns
), "ssh");
290 # ifdef WITH_AIXAUTHENTICATE
292 sys_auth_record_login(authctxt
->user
,
293 get_canonical_hostname(options
.use_dns
), "ssh", &loginmsg
);
296 #ifdef SSH_AUDIT_EVENTS
297 if (authenticated
== 0 && !authctxt
->postponed
)
298 audit_event(audit_classify_auth(method
));
303 * Check whether root logins are disallowed.
306 auth_root_allowed(char *method
)
308 switch (options
.permit_root_login
) {
311 case PERMIT_NO_PASSWD
:
312 if (strcmp(method
, "password") != 0)
315 case PERMIT_FORCED_ONLY
:
316 if (forced_command
) {
317 logit("Root login accepted for forced command.");
322 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
328 * Given a template and a passwd structure, build a filename
329 * by substituting % tokenised options. Currently, %% becomes '%',
330 * %h becomes the home directory and %u the username.
332 * This returns a buffer allocated by xmalloc.
335 expand_authorized_keys(const char *filename
, struct passwd
*pw
)
337 char *file
, ret
[MAXPATHLEN
];
340 file
= percent_expand(filename
, "h", pw
->pw_dir
,
341 "u", pw
->pw_name
, (char *)NULL
);
344 * Ensure that filename starts anchored. If not, be backward
345 * compatible and prepend the '%h/'
350 i
= snprintf(ret
, sizeof(ret
), "%s/%s", pw
->pw_dir
, file
);
351 if (i
< 0 || (size_t)i
>= sizeof(ret
))
352 fatal("expand_authorized_keys: path too long");
354 return (xstrdup(ret
));
358 authorized_keys_file(struct passwd
*pw
)
360 return expand_authorized_keys(options
.authorized_keys_file
, pw
);
364 authorized_keys_file2(struct passwd
*pw
)
366 return expand_authorized_keys(options
.authorized_keys_file2
, pw
);
369 /* return ok if key exists in sysfile or userfile */
371 check_key_in_hostfiles(struct passwd
*pw
, Key
*key
, const char *host
,
372 const char *sysfile
, const char *userfile
)
377 HostStatus host_status
;
379 /* Check if we know the host and its host key. */
380 found
= key_new(key
->type
);
381 host_status
= check_host_in_hostfile(sysfile
, host
, key
, found
, NULL
);
383 if (host_status
!= HOST_OK
&& userfile
!= NULL
) {
384 user_hostfile
= tilde_expand_filename(userfile
, pw
->pw_uid
);
385 if (options
.strict_modes
&&
386 (stat(user_hostfile
, &st
) == 0) &&
387 ((st
.st_uid
!= 0 && st
.st_uid
!= pw
->pw_uid
) ||
388 (st
.st_mode
& 022) != 0)) {
389 logit("Authentication refused for %.100s: "
390 "bad owner or modes for %.200s",
391 pw
->pw_name
, user_hostfile
);
393 temporarily_use_uid(pw
);
394 host_status
= check_host_in_hostfile(user_hostfile
,
395 host
, key
, found
, NULL
);
398 xfree(user_hostfile
);
402 debug2("check_key_in_hostfiles: key %s for %s", host_status
== HOST_OK
?
403 "ok" : "not found", host
);
409 * Check a given file for security. This is defined as all components
410 * of the path to the file must be owned by either the owner of
411 * of the file or root and no directories must be group or world writable.
413 * XXX Should any specific check be done for sym links ?
415 * Takes an open file descriptor, the file name, a uid and and
416 * error buffer plus max size as arguments.
418 * Returns 0 on success and -1 on failure
421 secure_filename(FILE *f
, const char *file
, struct passwd
*pw
,
422 char *err
, size_t errlen
)
424 uid_t uid
= pw
->pw_uid
;
425 char buf
[MAXPATHLEN
], homedir
[MAXPATHLEN
];
430 if (realpath(file
, buf
) == NULL
) {
431 snprintf(err
, errlen
, "realpath %s failed: %s", file
,
435 if (realpath(pw
->pw_dir
, homedir
) != NULL
)
438 /* check the open file to avoid races */
439 if (fstat(fileno(f
), &st
) < 0 ||
440 (st
.st_uid
!= 0 && st
.st_uid
!= uid
) ||
441 (st
.st_mode
& 022) != 0) {
442 snprintf(err
, errlen
, "bad ownership or modes for file %s",
447 /* for each component of the canonical path, walking upwards */
449 if ((cp
= dirname(buf
)) == NULL
) {
450 snprintf(err
, errlen
, "dirname() failed");
453 strlcpy(buf
, cp
, sizeof(buf
));
455 debug3("secure_filename: checking '%s'", buf
);
456 if (stat(buf
, &st
) < 0 ||
457 (st
.st_uid
!= 0 && st
.st_uid
!= uid
) ||
458 (st
.st_mode
& 022) != 0) {
459 snprintf(err
, errlen
,
460 "bad ownership or modes for directory %s", buf
);
464 /* If are past the homedir then we can stop */
465 if (comparehome
&& strcmp(homedir
, buf
) == 0) {
466 debug3("secure_filename: terminating check at '%s'",
471 * dirname should always complete with a "/" path,
472 * but we can be paranoid and check for "." too
474 if ((strcmp("/", buf
) == 0) || (strcmp(".", buf
) == 0))
481 auth_openkeyfile(const char *file
, struct passwd
*pw
, int strict_modes
)
489 * Open the file containing the authorized keys
490 * Fail quietly if file does not exist
492 if ((fd
= open(file
, O_RDONLY
|O_NONBLOCK
)) == -1) {
494 debug("Could not open keyfile '%s': %s", file
,
499 if (fstat(fd
, &st
) < 0) {
503 if (!S_ISREG(st
.st_mode
)) {
504 logit("User %s authorized keys %s is not a regular file",
510 if ((f
= fdopen(fd
, "r")) == NULL
) {
514 if (options
.strict_modes
&&
515 secure_filename(f
, file
, pw
, line
, sizeof(line
)) != 0) {
517 logit("Authentication refused: %s", line
);
525 getpwnamallow(const char *user
)
527 #ifdef HAVE_LOGIN_CAP
528 extern login_cap_t
*lc
;
535 parse_server_match_config(&options
, user
,
536 get_canonical_hostname(options
.use_dns
), get_remote_ipaddr());
538 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
544 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
549 * Windows usernames are case-insensitive. To avoid later problems
550 * when trying to match the username, the user is only allowed to
551 * login if the username is given in the same case as stored in the
554 if (pw
!= NULL
&& strcmp(user
, pw
->pw_name
) != 0) {
555 logit("Login name %.100s does not match stored username %.100s",
561 logit("Invalid user %.100s from %.100s",
562 user
, get_remote_ipaddr());
563 #ifdef CUSTOM_FAILED_LOGIN
564 record_failed_login(user
,
565 get_canonical_hostname(options
.use_dns
), "ssh");
567 #ifdef SSH_AUDIT_EVENTS
568 audit_event(SSH_INVALID_USER
);
569 #endif /* SSH_AUDIT_EVENTS */
572 if (!allowed_user(pw
))
574 #ifdef HAVE_LOGIN_CAP
575 if ((lc
= login_getclass(pw
->pw_class
)) == NULL
) {
576 debug("unable to get login class: %s", user
);
580 if ((as
= auth_open()) == NULL
|| auth_setpwd(as
, pw
) != 0 ||
581 auth_approval(as
, lc
, pw
->pw_name
, "ssh") <= 0) {
582 debug("Approval failure for %s", user
);
594 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
596 auth_key_is_revoked(Key
*key
)
600 if (options
.revoked_keys_file
== NULL
)
603 switch (key_in_file(key
, options
.revoked_keys_file
, 0)) {
605 /* key not revoked */
608 /* Error opening revoked_keys_file: refuse all keys */
609 error("Revoked keys file is unreadable: refusing public key "
614 key_fp
= key_fingerprint(key
, SSH_FP_MD5
, SSH_FP_HEX
);
615 error("WARNING: authentication attempt with a revoked "
616 "%s key %s ", key_type(key
), key_fp
);
620 fatal("key_in_file returned junk");
624 auth_debug_add(const char *fmt
,...)
629 if (!auth_debug_init
)
633 vsnprintf(buf
, sizeof(buf
), fmt
, args
);
635 buffer_put_cstring(&auth_debug
, buf
);
639 auth_debug_send(void)
643 if (!auth_debug_init
)
645 while (buffer_len(&auth_debug
)) {
646 msg
= buffer_get_string(&auth_debug
, NULL
);
647 packet_send_debug("%s", msg
);
653 auth_debug_reset(void)
656 buffer_clear(&auth_debug
);
658 buffer_init(&auth_debug
);
666 static struct passwd fake
;
668 memset(&fake
, 0, sizeof(fake
));
669 fake
.pw_name
= "NOUSER";
671 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
672 fake
.pw_gecos
= "NOUSER";
673 fake
.pw_uid
= privsep_pw
== NULL
? (uid_t
)-1 : privsep_pw
->pw_uid
;
674 fake
.pw_gid
= privsep_pw
== NULL
? (gid_t
)-1 : privsep_pw
->pw_gid
;
675 #ifdef HAVE_PW_CLASS_IN_PASSWD
678 fake
.pw_dir
= "/nonexist";
679 fake
.pw_shell
= "/nonexist";