- (dtucker) [contrib/aix/buildbff.sh] Fix creation of ssh_prng_cmds.default
[openssh-git.git] / auth.c
blob89a9360684b47d2699b38cbc49b337bc3dec21f4
1 /* $OpenBSD: auth.c,v 1.86 2010/03/05 02:58:11 djm Exp $ */
2 /*
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
7 * are met:
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.
26 #include "includes.h"
28 #include <sys/types.h>
29 #include <sys/stat.h>
30 #include <sys/param.h>
32 #include <netinet/in.h>
34 #include <errno.h>
35 #include <fcntl.h>
36 #ifdef HAVE_PATHS_H
37 # include <paths.h>
38 #endif
39 #include <pwd.h>
40 #ifdef HAVE_LOGIN_H
41 #include <login.h>
42 #endif
43 #ifdef USE_SHADOW
44 #include <shadow.h>
45 #endif
46 #ifdef HAVE_LIBGEN_H
47 #include <libgen.h>
48 #endif
49 #include <stdarg.h>
50 #include <stdio.h>
51 #include <string.h>
52 #include <unistd.h>
54 #include "xmalloc.h"
55 #include "match.h"
56 #include "groupaccess.h"
57 #include "log.h"
58 #include "buffer.h"
59 #include "servconf.h"
60 #include "key.h"
61 #include "hostfile.h"
62 #include "auth.h"
63 #include "auth-options.h"
64 #include "canohost.h"
65 #include "uidswap.h"
66 #include "misc.h"
67 #include "packet.h"
68 #include "loginrec.h"
69 #ifdef GSSAPI
70 #include "ssh-gss.h"
71 #endif
72 #include "authfile.h"
73 #include "monitor_wrap.h"
75 /* import */
76 extern ServerOptions options;
77 extern int use_privsep;
78 extern Buffer loginmsg;
79 extern struct passwd *privsep_pw;
81 /* Debugging messages */
82 Buffer auth_debug;
83 int auth_debug_init;
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.
94 int
95 allowed_user(struct passwd * pw)
97 struct stat st;
98 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
99 u_int i;
100 #ifdef USE_SHADOW
101 struct spwd *spw = NULL;
102 #endif
104 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
105 if (!pw || !pw->pw_name)
106 return 0;
108 #ifdef USE_SHADOW
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))
113 return 0;
114 #endif /* HAS_SHADOW_EXPIRE */
115 #endif /* USE_SHADOW */
117 /* grab passwd field for locked account check */
118 passwd = pw->pw_passwd;
119 #ifdef USE_SHADOW
120 if (spw != NULL)
121 #ifdef USE_LIBIAF
122 passwd = get_iaf_password(pw);
123 #else
124 passwd = spw->sp_pwdp;
125 #endif /* USE_LIBIAF */
126 #endif
128 /* check for locked account */
129 if (!options.use_pam && passwd && *passwd) {
130 int locked = 0;
132 #ifdef LOCKED_PASSWD_STRING
133 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
134 locked = 1;
135 #endif
136 #ifdef LOCKED_PASSWD_PREFIX
137 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
138 strlen(LOCKED_PASSWD_PREFIX)) == 0)
139 locked = 1;
140 #endif
141 #ifdef LOCKED_PASSWD_SUBSTR
142 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
143 locked = 1;
144 #endif
145 #ifdef USE_LIBIAF
146 free(passwd);
147 #endif /* USE_LIBIAF */
148 if (locked) {
149 logit("User %.100s not allowed because account is locked",
150 pw->pw_name);
151 return 0;
156 * Deny if shell does not exist or is not executable unless we
157 * are chrooting.
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);
167 xfree(shell);
168 return 0;
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);
174 xfree(shell);
175 return 0;
177 xfree(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);
194 return 0;
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]))
202 break;
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);
207 return 0;
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);
215 return 0;
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)) {
222 ga_free();
223 logit("User %.100s from %.100s not allowed "
224 "because a group is listed in DenyGroups",
225 pw->pw_name, hostname);
226 return 0;
229 * Return false if AllowGroups isn't empty and one of user's groups
230 * isn't listed there
232 if (options.num_allow_groups > 0)
233 if (!ga_match(options.allow_groups,
234 options.num_allow_groups)) {
235 ga_free();
236 logit("User %.100s from %.100s not allowed "
237 "because none of user's groups are listed "
238 "in AllowGroups", pw->pw_name, hostname);
239 return 0;
241 ga_free();
244 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
245 if (!sys_auth_allowed_user(pw, &loginmsg))
246 return 0;
247 #endif
249 /* We found no reason not to let this user try to log on... */
250 return 1;
253 void
254 auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
256 void (*authlog) (const char *fmt,...) = verbose;
257 char *authmsg;
259 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
260 return;
262 /* Raise logging level */
263 if (authenticated == 1 ||
264 !authctxt->valid ||
265 authctxt->failures >= options.max_authtries / 2 ||
266 strcmp(method, "password") == 0)
267 authlog = logit;
269 if (authctxt->postponed)
270 authmsg = "Postponed";
271 else
272 authmsg = authenticated ? "Accepted" : "Failed";
274 authlog("%s %s for %s%.100s from %.200s port %d%s",
275 authmsg,
276 method,
277 authctxt->valid ? "" : "invalid user ",
278 authctxt->user,
279 get_remote_ipaddr(),
280 get_remote_port(),
281 info);
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
291 if (authenticated)
292 sys_auth_record_login(authctxt->user,
293 get_canonical_hostname(options.use_dns), "ssh", &loginmsg);
294 # endif
295 #endif
296 #ifdef SSH_AUDIT_EVENTS
297 if (authenticated == 0 && !authctxt->postponed)
298 audit_event(audit_classify_auth(method));
299 #endif
303 * Check whether root logins are disallowed.
306 auth_root_allowed(char *method)
308 switch (options.permit_root_login) {
309 case PERMIT_YES:
310 return 1;
311 case PERMIT_NO_PASSWD:
312 if (strcmp(method, "password") != 0)
313 return 1;
314 break;
315 case PERMIT_FORCED_ONLY:
316 if (forced_command) {
317 logit("Root login accepted for forced command.");
318 return 1;
320 break;
322 logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
323 return 0;
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.
334 static char *
335 expand_authorized_keys(const char *filename, struct passwd *pw)
337 char *file, ret[MAXPATHLEN];
338 int i;
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/'
347 if (*file == '/')
348 return (file);
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");
353 xfree(file);
354 return (xstrdup(ret));
357 char *
358 authorized_keys_file(struct passwd *pw)
360 return expand_authorized_keys(options.authorized_keys_file, pw);
363 char *
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 */
370 HostStatus
371 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
372 const char *sysfile, const char *userfile)
374 Key *found;
375 char *user_hostfile;
376 struct stat st;
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);
392 } else {
393 temporarily_use_uid(pw);
394 host_status = check_host_in_hostfile(user_hostfile,
395 host, key, found, NULL);
396 restore_uid();
398 xfree(user_hostfile);
400 key_free(found);
402 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
403 "ok" : "not found", host);
404 return host_status;
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
420 static int
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];
426 char *cp;
427 int comparehome = 0;
428 struct stat st;
430 if (realpath(file, buf) == NULL) {
431 snprintf(err, errlen, "realpath %s failed: %s", file,
432 strerror(errno));
433 return -1;
435 if (realpath(pw->pw_dir, homedir) != NULL)
436 comparehome = 1;
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",
443 buf);
444 return -1;
447 /* for each component of the canonical path, walking upwards */
448 for (;;) {
449 if ((cp = dirname(buf)) == NULL) {
450 snprintf(err, errlen, "dirname() failed");
451 return -1;
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);
461 return -1;
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'",
467 buf);
468 break;
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))
475 break;
477 return 0;
480 FILE *
481 auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
483 char line[1024];
484 struct stat st;
485 int fd;
486 FILE *f;
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) {
493 if (errno != ENOENT)
494 debug("Could not open keyfile '%s': %s", file,
495 strerror(errno));
496 return NULL;
499 if (fstat(fd, &st) < 0) {
500 close(fd);
501 return NULL;
503 if (!S_ISREG(st.st_mode)) {
504 logit("User %s authorized keys %s is not a regular file",
505 pw->pw_name, file);
506 close(fd);
507 return NULL;
509 unset_nonblock(fd);
510 if ((f = fdopen(fd, "r")) == NULL) {
511 close(fd);
512 return NULL;
514 if (options.strict_modes &&
515 secure_filename(f, file, pw, line, sizeof(line)) != 0) {
516 fclose(f);
517 logit("Authentication refused: %s", line);
518 return NULL;
521 return f;
524 struct passwd *
525 getpwnamallow(const char *user)
527 #ifdef HAVE_LOGIN_CAP
528 extern login_cap_t *lc;
529 #ifdef BSD_AUTH
530 auth_session_t *as;
531 #endif
532 #endif
533 struct passwd *pw;
535 parse_server_match_config(&options, user,
536 get_canonical_hostname(options.use_dns), get_remote_ipaddr());
538 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
539 aix_setauthdb(user);
540 #endif
542 pw = getpwnam(user);
544 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
545 aix_restoreauthdb();
546 #endif
547 #ifdef HAVE_CYGWIN
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
552 * user database.
554 if (pw != NULL && strcmp(user, pw->pw_name) != 0) {
555 logit("Login name %.100s does not match stored username %.100s",
556 user, pw->pw_name);
557 pw = NULL;
559 #endif
560 if (pw == NULL) {
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");
566 #endif
567 #ifdef SSH_AUDIT_EVENTS
568 audit_event(SSH_INVALID_USER);
569 #endif /* SSH_AUDIT_EVENTS */
570 return (NULL);
572 if (!allowed_user(pw))
573 return (NULL);
574 #ifdef HAVE_LOGIN_CAP
575 if ((lc = login_getclass(pw->pw_class)) == NULL) {
576 debug("unable to get login class: %s", user);
577 return (NULL);
579 #ifdef BSD_AUTH
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);
583 pw = NULL;
585 if (as != NULL)
586 auth_close(as);
587 #endif
588 #endif
589 if (pw != NULL)
590 return (pwcopy(pw));
591 return (NULL);
594 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
596 auth_key_is_revoked(Key *key)
598 char *key_fp;
600 if (options.revoked_keys_file == NULL)
601 return 0;
603 switch (key_in_file(key, options.revoked_keys_file, 0)) {
604 case 0:
605 /* key not revoked */
606 return 0;
607 case -1:
608 /* Error opening revoked_keys_file: refuse all keys */
609 error("Revoked keys file is unreadable: refusing public key "
610 "authentication");
611 return 1;
612 case 1:
613 /* Key revoked */
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);
617 xfree(key_fp);
618 return 1;
620 fatal("key_in_file returned junk");
623 void
624 auth_debug_add(const char *fmt,...)
626 char buf[1024];
627 va_list args;
629 if (!auth_debug_init)
630 return;
632 va_start(args, fmt);
633 vsnprintf(buf, sizeof(buf), fmt, args);
634 va_end(args);
635 buffer_put_cstring(&auth_debug, buf);
638 void
639 auth_debug_send(void)
641 char *msg;
643 if (!auth_debug_init)
644 return;
645 while (buffer_len(&auth_debug)) {
646 msg = buffer_get_string(&auth_debug, NULL);
647 packet_send_debug("%s", msg);
648 xfree(msg);
652 void
653 auth_debug_reset(void)
655 if (auth_debug_init)
656 buffer_clear(&auth_debug);
657 else {
658 buffer_init(&auth_debug);
659 auth_debug_init = 1;
663 struct passwd *
664 fakepw(void)
666 static struct passwd fake;
668 memset(&fake, 0, sizeof(fake));
669 fake.pw_name = "NOUSER";
670 fake.pw_passwd =
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
676 fake.pw_class = "";
677 #endif
678 fake.pw_dir = "/nonexist";
679 fake.pw_shell = "/nonexist";
681 return (&fake);