1 /* $OpenBSD: auth.c,v 1.78 2007/09/21 08:15:29 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>
54 #include "groupaccess.h"
61 #include "auth-options.h"
70 #include "monitor_wrap.h"
73 extern ServerOptions options
;
74 extern int use_privsep
;
75 extern Buffer loginmsg
;
76 extern struct passwd
*privsep_pw
;
78 /* Debugging messages */
83 * Check if the user is allowed to log in via ssh. If user is listed
84 * in DenyUsers or one of user's groups is listed in DenyGroups, false
85 * will be returned. If AllowUsers isn't empty and user isn't listed
86 * there, or if AllowGroups isn't empty and one of user's groups isn't
87 * listed there, false will be returned.
88 * If the user's shell is not executable, false will be returned.
89 * Otherwise true is returned.
92 allowed_user(struct passwd
* pw
)
95 const char *hostname
= NULL
, *ipaddr
= NULL
, *passwd
= NULL
;
99 struct spwd
*spw
= NULL
;
102 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
103 if (!pw
|| !pw
->pw_name
)
107 if (!options
.use_pam
)
108 spw
= getspnam(pw
->pw_name
);
109 #ifdef HAS_SHADOW_EXPIRE
110 if (!options
.use_pam
&& spw
!= NULL
&& auth_shadow_acctexpired(spw
))
112 #endif /* HAS_SHADOW_EXPIRE */
113 #endif /* USE_SHADOW */
115 /* grab passwd field for locked account check */
119 passwd
= get_iaf_password(pw
);
121 passwd
= spw
->sp_pwdp
;
122 #endif /* USE_LIBIAF */
124 passwd
= pw
->pw_passwd
;
127 /* check for locked account */
128 if (!options
.use_pam
&& passwd
&& *passwd
) {
131 #ifdef LOCKED_PASSWD_STRING
132 if (strcmp(passwd
, LOCKED_PASSWD_STRING
) == 0)
135 #ifdef LOCKED_PASSWD_PREFIX
136 if (strncmp(passwd
, LOCKED_PASSWD_PREFIX
,
137 strlen(LOCKED_PASSWD_PREFIX
)) == 0)
140 #ifdef LOCKED_PASSWD_SUBSTR
141 if (strstr(passwd
, LOCKED_PASSWD_SUBSTR
))
146 #endif /* USE_LIBIAF */
148 logit("User %.100s not allowed because account is locked",
155 * Get the shell from the password data. An empty shell field is
156 * legal, and means /bin/sh.
158 shell
= (pw
->pw_shell
[0] == '\0') ? _PATH_BSHELL
: pw
->pw_shell
;
160 /* deny if shell does not exists or is not executable */
161 if (stat(shell
, &st
) != 0) {
162 logit("User %.100s not allowed because shell %.100s does not exist",
166 if (S_ISREG(st
.st_mode
) == 0 ||
167 (st
.st_mode
& (S_IXOTH
|S_IXUSR
|S_IXGRP
)) == 0) {
168 logit("User %.100s not allowed because shell %.100s is not executable",
173 if (options
.num_deny_users
> 0 || options
.num_allow_users
> 0 ||
174 options
.num_deny_groups
> 0 || options
.num_allow_groups
> 0) {
175 hostname
= get_canonical_hostname(options
.use_dns
);
176 ipaddr
= get_remote_ipaddr();
179 /* Return false if user is listed in DenyUsers */
180 if (options
.num_deny_users
> 0) {
181 for (i
= 0; i
< options
.num_deny_users
; i
++)
182 if (match_user(pw
->pw_name
, hostname
, ipaddr
,
183 options
.deny_users
[i
])) {
184 logit("User %.100s from %.100s not allowed "
185 "because listed in DenyUsers",
186 pw
->pw_name
, hostname
);
190 /* Return false if AllowUsers isn't empty and user isn't listed there */
191 if (options
.num_allow_users
> 0) {
192 for (i
= 0; i
< options
.num_allow_users
; i
++)
193 if (match_user(pw
->pw_name
, hostname
, ipaddr
,
194 options
.allow_users
[i
]))
196 /* i < options.num_allow_users iff we break for loop */
197 if (i
>= options
.num_allow_users
) {
198 logit("User %.100s from %.100s not allowed because "
199 "not listed in AllowUsers", pw
->pw_name
, hostname
);
203 if (options
.num_deny_groups
> 0 || options
.num_allow_groups
> 0) {
204 /* Get the user's group access list (primary and supplementary) */
205 if (ga_init(pw
->pw_name
, pw
->pw_gid
) == 0) {
206 logit("User %.100s from %.100s not allowed because "
207 "not in any group", pw
->pw_name
, hostname
);
211 /* Return false if one of user's groups is listed in DenyGroups */
212 if (options
.num_deny_groups
> 0)
213 if (ga_match(options
.deny_groups
,
214 options
.num_deny_groups
)) {
216 logit("User %.100s from %.100s not allowed "
217 "because a group is listed in DenyGroups",
218 pw
->pw_name
, hostname
);
222 * Return false if AllowGroups isn't empty and one of user's groups
225 if (options
.num_allow_groups
> 0)
226 if (!ga_match(options
.allow_groups
,
227 options
.num_allow_groups
)) {
229 logit("User %.100s from %.100s not allowed "
230 "because none of user's groups are listed "
231 "in AllowGroups", pw
->pw_name
, hostname
);
237 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
238 if (!sys_auth_allowed_user(pw
, &loginmsg
))
242 /* We found no reason not to let this user try to log on... */
247 auth_log(Authctxt
*authctxt
, int authenticated
, char *method
, char *info
)
249 void (*authlog
) (const char *fmt
,...) = verbose
;
252 if (use_privsep
&& !mm_is_monitor() && !authctxt
->postponed
)
255 /* Raise logging level */
256 if (authenticated
== 1 ||
258 authctxt
->failures
>= options
.max_authtries
/ 2 ||
259 strcmp(method
, "password") == 0)
262 if (authctxt
->postponed
)
263 authmsg
= "Postponed";
265 authmsg
= authenticated
? "Accepted" : "Failed";
267 authlog("%s %s for %s%.100s from %.200s port %d%s",
270 authctxt
->valid
? "" : "invalid user ",
276 #ifdef CUSTOM_FAILED_LOGIN
277 if (authenticated
== 0 && !authctxt
->postponed
&&
278 (strcmp(method
, "password") == 0 ||
279 strncmp(method
, "keyboard-interactive", 20) == 0 ||
280 strcmp(method
, "challenge-response") == 0))
281 record_failed_login(authctxt
->user
,
282 get_canonical_hostname(options
.use_dns
), "ssh");
283 # ifdef WITH_AIXAUTHENTICATE
285 sys_auth_record_login(authctxt
->user
,
286 get_canonical_hostname(options
.use_dns
), "ssh", &loginmsg
);
289 #ifdef SSH_AUDIT_EVENTS
290 if (authenticated
== 0 && !authctxt
->postponed
)
291 audit_event(audit_classify_auth(method
));
296 * Check whether root logins are disallowed.
299 auth_root_allowed(char *method
)
301 switch (options
.permit_root_login
) {
304 case PERMIT_NO_PASSWD
:
305 if (strcmp(method
, "password") != 0)
308 case PERMIT_FORCED_ONLY
:
309 if (forced_command
) {
310 logit("Root login accepted for forced command.");
315 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
321 * Given a template and a passwd structure, build a filename
322 * by substituting % tokenised options. Currently, %% becomes '%',
323 * %h becomes the home directory and %u the username.
325 * This returns a buffer allocated by xmalloc.
328 expand_authorized_keys(const char *filename
, struct passwd
*pw
)
330 char *file
, ret
[MAXPATHLEN
];
333 file
= percent_expand(filename
, "h", pw
->pw_dir
,
334 "u", pw
->pw_name
, (char *)NULL
);
337 * Ensure that filename starts anchored. If not, be backward
338 * compatible and prepend the '%h/'
343 i
= snprintf(ret
, sizeof(ret
), "%s/%s", pw
->pw_dir
, file
);
344 if (i
< 0 || (size_t)i
>= sizeof(ret
))
345 fatal("expand_authorized_keys: path too long");
347 return (xstrdup(ret
));
351 authorized_keys_file(struct passwd
*pw
)
353 return expand_authorized_keys(options
.authorized_keys_file
, pw
);
357 authorized_keys_file2(struct passwd
*pw
)
359 return expand_authorized_keys(options
.authorized_keys_file2
, pw
);
362 /* return ok if key exists in sysfile or userfile */
364 check_key_in_hostfiles(struct passwd
*pw
, Key
*key
, const char *host
,
365 const char *sysfile
, const char *userfile
)
370 HostStatus host_status
;
372 /* Check if we know the host and its host key. */
373 found
= key_new(key
->type
);
374 host_status
= check_host_in_hostfile(sysfile
, host
, key
, found
, NULL
);
376 if (host_status
!= HOST_OK
&& userfile
!= NULL
) {
377 user_hostfile
= tilde_expand_filename(userfile
, pw
->pw_uid
);
378 if (options
.strict_modes
&&
379 (stat(user_hostfile
, &st
) == 0) &&
380 ((st
.st_uid
!= 0 && st
.st_uid
!= pw
->pw_uid
) ||
381 (st
.st_mode
& 022) != 0)) {
382 logit("Authentication refused for %.100s: "
383 "bad owner or modes for %.200s",
384 pw
->pw_name
, user_hostfile
);
386 temporarily_use_uid(pw
);
387 host_status
= check_host_in_hostfile(user_hostfile
,
388 host
, key
, found
, NULL
);
391 xfree(user_hostfile
);
395 debug2("check_key_in_hostfiles: key %s for %s", host_status
== HOST_OK
?
396 "ok" : "not found", host
);
402 * Check a given file for security. This is defined as all components
403 * of the path to the file must be owned by either the owner of
404 * of the file or root and no directories must be group or world writable.
406 * XXX Should any specific check be done for sym links ?
408 * Takes an open file descriptor, the file name, a uid and and
409 * error buffer plus max size as arguments.
411 * Returns 0 on success and -1 on failure
414 secure_filename(FILE *f
, const char *file
, struct passwd
*pw
,
415 char *err
, size_t errlen
)
417 uid_t uid
= pw
->pw_uid
;
418 char buf
[MAXPATHLEN
], homedir
[MAXPATHLEN
];
423 if (realpath(file
, buf
) == NULL
) {
424 snprintf(err
, errlen
, "realpath %s failed: %s", file
,
428 if (realpath(pw
->pw_dir
, homedir
) != NULL
)
431 /* check the open file to avoid races */
432 if (fstat(fileno(f
), &st
) < 0 ||
433 (st
.st_uid
!= 0 && st
.st_uid
!= uid
) ||
434 (st
.st_mode
& 022) != 0) {
435 snprintf(err
, errlen
, "bad ownership or modes for file %s",
440 /* for each component of the canonical path, walking upwards */
442 if ((cp
= dirname(buf
)) == NULL
) {
443 snprintf(err
, errlen
, "dirname() failed");
446 strlcpy(buf
, cp
, sizeof(buf
));
448 debug3("secure_filename: checking '%s'", buf
);
449 if (stat(buf
, &st
) < 0 ||
450 (st
.st_uid
!= 0 && st
.st_uid
!= uid
) ||
451 (st
.st_mode
& 022) != 0) {
452 snprintf(err
, errlen
,
453 "bad ownership or modes for directory %s", buf
);
457 /* If are passed the homedir then we can stop */
458 if (comparehome
&& strcmp(homedir
, buf
) == 0) {
459 debug3("secure_filename: terminating check at '%s'",
464 * dirname should always complete with a "/" path,
465 * but we can be paranoid and check for "." too
467 if ((strcmp("/", buf
) == 0) || (strcmp(".", buf
) == 0))
474 getpwnamallow(const char *user
)
476 #ifdef HAVE_LOGIN_CAP
477 extern login_cap_t
*lc
;
484 parse_server_match_config(&options
, user
,
485 get_canonical_hostname(options
.use_dns
), get_remote_ipaddr());
489 logit("Invalid user %.100s from %.100s",
490 user
, get_remote_ipaddr());
491 #ifdef CUSTOM_FAILED_LOGIN
492 record_failed_login(user
,
493 get_canonical_hostname(options
.use_dns
), "ssh");
495 #ifdef SSH_AUDIT_EVENTS
496 audit_event(SSH_INVALID_USER
);
497 #endif /* SSH_AUDIT_EVENTS */
500 if (!allowed_user(pw
))
502 #ifdef HAVE_LOGIN_CAP
503 if ((lc
= login_getclass(pw
->pw_class
)) == NULL
) {
504 debug("unable to get login class: %s", user
);
508 if ((as
= auth_open()) == NULL
|| auth_setpwd(as
, pw
) != 0 ||
509 auth_approval(as
, lc
, pw
->pw_name
, "ssh") <= 0) {
510 debug("Approval failure for %s", user
);
523 auth_debug_add(const char *fmt
,...)
528 if (!auth_debug_init
)
532 vsnprintf(buf
, sizeof(buf
), fmt
, args
);
534 buffer_put_cstring(&auth_debug
, buf
);
538 auth_debug_send(void)
542 if (!auth_debug_init
)
544 while (buffer_len(&auth_debug
)) {
545 msg
= buffer_get_string(&auth_debug
, NULL
);
546 packet_send_debug("%s", msg
);
552 auth_debug_reset(void)
555 buffer_clear(&auth_debug
);
557 buffer_init(&auth_debug
);
565 static struct passwd fake
;
567 memset(&fake
, 0, sizeof(fake
));
568 fake
.pw_name
= "NOUSER";
570 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
571 fake
.pw_gecos
= "NOUSER";
572 fake
.pw_uid
= privsep_pw
== NULL
? (uid_t
)-1 : privsep_pw
->pw_uid
;
573 fake
.pw_gid
= privsep_pw
== NULL
? (gid_t
)-1 : privsep_pw
->pw_gid
;
574 #ifdef HAVE_PW_CLASS_IN_PASSWD
577 fake
.pw_dir
= "/nonexist";
578 fake
.pw_shell
= "/nonexist";