1 /* $OpenBSD: auth.c,v 1.124 2017/09/12 06:32:07 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/socket.h>
32 #include <netinet/in.h>
55 #include "groupaccess.h"
63 #include "auth-options.h"
72 #include "monitor_wrap.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)
99 struct ssh *ssh = active_state; /* XXX */
101 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
105 struct spwd *spw = NULL;
108 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
109 if (!pw || !pw->pw_name)
113 if (!options.use_pam)
114 spw = getspnam(pw->pw_name);
115 #ifdef HAS_SHADOW_EXPIRE
116 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
118 #endif /* HAS_SHADOW_EXPIRE */
119 #endif /* USE_SHADOW */
121 /* grab passwd field for locked account check */
122 passwd = pw->pw_passwd;
126 passwd = get_iaf_password(pw);
128 passwd = spw->sp_pwdp;
129 #endif /* USE_LIBIAF */
132 /* check for locked account */
133 if (!options.use_pam && passwd && *passwd) {
136 #ifdef LOCKED_PASSWD_STRING
137 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
140 #ifdef LOCKED_PASSWD_PREFIX
141 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
142 strlen(LOCKED_PASSWD_PREFIX)) == 0)
145 #ifdef LOCKED_PASSWD_SUBSTR
146 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
150 free((void *) passwd);
151 #endif /* USE_LIBIAF */
153 logit("User %.100s not allowed because account is locked",
160 * Deny if shell does not exist or is not executable unless we
163 if (options.chroot_directory == NULL ||
164 strcasecmp(options.chroot_directory, "none") == 0) {
165 char *shell = xstrdup((pw->pw_shell[0] == '\0') ?
166 _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */
168 if (stat(shell, &st) != 0) {
169 logit("User %.100s not allowed because shell %.100s "
170 "does not exist", pw->pw_name, shell);
174 if (S_ISREG(st.st_mode) == 0 ||
175 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
176 logit("User %.100s not allowed because shell %.100s "
177 "is not executable", pw->pw_name, shell);
184 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
185 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
186 hostname = auth_get_canonical_hostname(ssh, options.use_dns);
187 ipaddr = ssh_remote_ipaddr(ssh);
190 /* Return false if user is listed in DenyUsers */
191 if (options.num_deny_users > 0) {
192 for (i = 0; i < options.num_deny_users; i++) {
193 r = match_user(pw->pw_name, hostname, ipaddr,
194 options.deny_users[i]);
196 fatal("Invalid DenyUsers pattern \"%.100s\"",
197 options.deny_users[i]);
199 logit("User %.100s from %.100s not allowed "
200 "because listed in DenyUsers",
201 pw->pw_name, hostname);
206 /* Return false if AllowUsers isn't empty and user isn't listed there */
207 if (options.num_allow_users > 0) {
208 for (i = 0; i < options.num_allow_users; i++) {
209 r = match_user(pw->pw_name, hostname, ipaddr,
210 options.allow_users[i]);
212 fatal("Invalid AllowUsers pattern \"%.100s\"",
213 options.allow_users[i]);
217 /* i < options.num_allow_users iff we break for loop */
218 if (i >= options.num_allow_users) {
219 logit("User %.100s from %.100s not allowed because "
220 "not listed in AllowUsers", pw->pw_name, hostname);
224 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
225 /* Get the user's group access list (primary and supplementary) */
226 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
227 logit("User %.100s from %.100s not allowed because "
228 "not in any group", pw->pw_name, hostname);
232 /* Return false if one of user's groups is listed in DenyGroups */
233 if (options.num_deny_groups > 0)
234 if (ga_match(options.deny_groups,
235 options.num_deny_groups)) {
237 logit("User %.100s from %.100s not allowed "
238 "because a group is listed in DenyGroups",
239 pw->pw_name, hostname);
243 * Return false if AllowGroups isn't empty and one of user's groups
246 if (options.num_allow_groups > 0)
247 if (!ga_match(options.allow_groups,
248 options.num_allow_groups)) {
250 logit("User %.100s from %.100s not allowed "
251 "because none of user's groups are listed "
252 "in AllowGroups", pw->pw_name, hostname);
258 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
259 if (!sys_auth_allowed_user(pw, &loginmsg))
263 /* We found no reason not to let this user try to log on... */
268 * Formats any key left in authctxt->auth_method_key for inclusion in
269 * auth_log()'s message. Also includes authxtct->auth_method_info if present.
272 format_method_key(Authctxt *authctxt)
274 const struct sshkey *key = authctxt->auth_method_key;
275 const char *methinfo = authctxt->auth_method_info;
276 char *fp, *ret = NULL;
281 if (key_is_cert(key)) {
282 fp = sshkey_fingerprint(key->cert->signature_key,
283 options.fingerprint_hash, SSH_FP_DEFAULT);
284 xasprintf(&ret, "%s ID %s (serial %llu) CA %s %s%s%s",
285 sshkey_type(key), key->cert->key_id,
286 (unsigned long long)key->cert->serial,
287 sshkey_type(key->cert->signature_key),
288 fp == NULL ? "(null)" : fp,
289 methinfo == NULL ? "" : ", ",
290 methinfo == NULL ? "" : methinfo);
293 fp = sshkey_fingerprint(key, options.fingerprint_hash,
295 xasprintf(&ret, "%s %s%s%s", sshkey_type(key),
296 fp == NULL ? "(null)" : fp,
297 methinfo == NULL ? "" : ", ",
298 methinfo == NULL ? "" : methinfo);
305 auth_log(Authctxt *authctxt, int authenticated, int partial,
306 const char *method, const char *submethod)
308 struct ssh *ssh = active_state; /* XXX */
309 void (*authlog) (const char *fmt,...) = verbose;
313 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
316 /* Raise logging level */
317 if (authenticated == 1 ||
319 authctxt->failures >= options.max_authtries / 2 ||
320 strcmp(method, "password") == 0)
323 if (authctxt->postponed)
324 authmsg = "Postponed";
328 authmsg = authenticated ? "Accepted" : "Failed";
330 if ((extra = format_method_key(authctxt)) == NULL) {
331 if (authctxt->auth_method_info != NULL)
332 extra = xstrdup(authctxt->auth_method_info);
335 authlog("%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s",
338 submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod,
339 authctxt->valid ? "" : "invalid user ",
341 ssh_remote_ipaddr(ssh),
342 ssh_remote_port(ssh),
343 extra != NULL ? ": " : "",
344 extra != NULL ? extra : "");
348 #ifdef CUSTOM_FAILED_LOGIN
349 if (authenticated == 0 && !authctxt->postponed &&
350 (strcmp(method, "password") == 0 ||
351 strncmp(method, "keyboard-interactive", 20) == 0 ||
352 strcmp(method, "challenge-response") == 0))
353 record_failed_login(authctxt->user,
354 auth_get_canonical_hostname(ssh, options.use_dns), "ssh");
355 # ifdef WITH_AIXAUTHENTICATE
357 sys_auth_record_login(authctxt->user,
358 auth_get_canonical_hostname(ssh, options.use_dns), "ssh",
362 #ifdef SSH_AUDIT_EVENTS
363 if (authenticated == 0 && !authctxt->postponed)
364 audit_event(audit_classify_auth(method));
370 auth_maxtries_exceeded(Authctxt *authctxt)
372 struct ssh *ssh = active_state; /* XXX */
374 error("maximum authentication attempts exceeded for "
375 "%s%.100s from %.200s port %d ssh2",
376 authctxt->valid ? "" : "invalid user ",
378 ssh_remote_ipaddr(ssh),
379 ssh_remote_port(ssh));
380 packet_disconnect("Too many authentication failures");
385 * Check whether root logins are disallowed.
388 auth_root_allowed(const char *method)
390 struct ssh *ssh = active_state; /* XXX */
392 switch (options.permit_root_login) {
395 case PERMIT_NO_PASSWD:
396 if (strcmp(method, "publickey") == 0 ||
397 strcmp(method, "hostbased") == 0 ||
398 strcmp(method, "gssapi-with-mic") == 0)
401 case PERMIT_FORCED_ONLY:
402 if (forced_command) {
403 logit("Root login accepted for forced command.");
408 logit("ROOT LOGIN REFUSED FROM %.200s port %d",
409 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
415 * Given a template and a passwd structure, build a filename
416 * by substituting % tokenised options. Currently, %% becomes '%',
417 * %h becomes the home directory and %u the username.
419 * This returns a buffer allocated by xmalloc.
422 expand_authorized_keys(const char *filename, struct passwd *pw)
424 char *file, ret[PATH_MAX];
427 file = percent_expand(filename, "h", pw->pw_dir,
428 "u", pw->pw_name, (char *)NULL);
431 * Ensure that filename starts anchored. If not, be backward
432 * compatible and prepend the '%h/'
437 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
438 if (i < 0 || (size_t)i >= sizeof(ret))
439 fatal("expand_authorized_keys: path too long");
441 return (xstrdup(ret));
445 authorized_principals_file(struct passwd *pw)
447 if (options.authorized_principals_file == NULL)
449 return expand_authorized_keys(options.authorized_principals_file, pw);
452 /* return ok if key exists in sysfile or userfile */
454 check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host,
455 const char *sysfile, const char *userfile)
459 HostStatus host_status;
460 struct hostkeys *hostkeys;
461 const struct hostkey_entry *found;
463 hostkeys = init_hostkeys();
464 load_hostkeys(hostkeys, host, sysfile);
465 if (userfile != NULL) {
466 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
467 if (options.strict_modes &&
468 (stat(user_hostfile, &st) == 0) &&
469 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
470 (st.st_mode & 022) != 0)) {
471 logit("Authentication refused for %.100s: "
472 "bad owner or modes for %.200s",
473 pw->pw_name, user_hostfile);
474 auth_debug_add("Ignored %.200s: bad ownership or modes",
477 temporarily_use_uid(pw);
478 load_hostkeys(hostkeys, host, user_hostfile);
483 host_status = check_key_in_hostkeys(hostkeys, key, &found);
484 if (host_status == HOST_REVOKED)
485 error("WARNING: revoked key for %s attempted authentication",
487 else if (host_status == HOST_OK)
488 debug("%s: key for %s found at %s:%ld", __func__,
489 found->host, found->file, found->line);
491 debug("%s: key for host %s not found", __func__, host);
493 free_hostkeys(hostkeys);
499 auth_openfile(const char *file, struct passwd *pw, int strict_modes,
500 int log_missing, char *file_type)
507 if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) {
508 if (log_missing || errno != ENOENT)
509 debug("Could not open %s '%s': %s", file_type, file,
514 if (fstat(fd, &st) < 0) {
518 if (!S_ISREG(st.st_mode)) {
519 logit("User %s %s %s is not a regular file",
520 pw->pw_name, file_type, file);
525 if ((f = fdopen(fd, "r")) == NULL) {
530 safe_path_fd(fileno(f), file, pw, line, sizeof(line)) != 0) {
532 logit("Authentication refused: %s", line);
533 auth_debug_add("Ignored %s: %s", file_type, line);
542 auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
544 return auth_openfile(file, pw, strict_modes, 1, "authorized keys");
548 auth_openprincipals(const char *file, struct passwd *pw, int strict_modes)
550 return auth_openfile(file, pw, strict_modes, 0,
551 "authorized principals");
555 getpwnamallow(const char *user)
557 struct ssh *ssh = active_state; /* XXX */
558 #ifdef HAVE_LOGIN_CAP
559 extern login_cap_t *lc;
565 struct connection_info *ci = get_connection_info(1, options.use_dns);
568 parse_server_match_config(&options, ci);
569 log_change_level(options.log_level);
570 process_permitopen(ssh, &options);
572 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
578 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
583 * Windows usernames are case-insensitive. To avoid later problems
584 * when trying to match the username, the user is only allowed to
585 * login if the username is given in the same case as stored in the
588 if (pw != NULL && strcmp(user, pw->pw_name) != 0) {
589 logit("Login name %.100s does not match stored username %.100s",
595 logit("Invalid user %.100s from %.100s port %d",
596 user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
597 #ifdef CUSTOM_FAILED_LOGIN
598 record_failed_login(user,
599 auth_get_canonical_hostname(ssh, options.use_dns), "ssh");
601 #ifdef SSH_AUDIT_EVENTS
602 audit_event(SSH_INVALID_USER);
603 #endif /* SSH_AUDIT_EVENTS */
606 if (!allowed_user(pw))
608 #ifdef HAVE_LOGIN_CAP
609 if ((lc = login_getclass(pw->pw_class)) == NULL) {
610 debug("unable to get login class: %s", user);
614 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
615 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
616 debug("Approval failure for %s", user);
628 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
630 auth_key_is_revoked(struct sshkey *key)
635 if (options.revoked_keys_file == NULL)
637 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
638 SSH_FP_DEFAULT)) == NULL) {
639 r = SSH_ERR_ALLOC_FAIL;
640 error("%s: fingerprint key: %s", __func__, ssh_err(r));
644 r = sshkey_check_revoked(key, options.revoked_keys_file);
647 break; /* not revoked */
648 case SSH_ERR_KEY_REVOKED:
649 error("Authentication key %s %s revoked by file %s",
650 sshkey_type(key), fp, options.revoked_keys_file);
653 error("Error checking authentication key %s %s in "
654 "revoked keys file %s: %s", sshkey_type(key), fp,
655 options.revoked_keys_file, ssh_err(r));
664 return r == 0 ? 0 : 1;
668 auth_debug_add(const char *fmt,...)
673 if (!auth_debug_init)
677 vsnprintf(buf, sizeof(buf), fmt, args);
679 buffer_put_cstring(&auth_debug, buf);
683 auth_debug_send(void)
687 if (!auth_debug_init)
689 while (buffer_len(&auth_debug)) {
690 msg = buffer_get_string(&auth_debug, NULL);
691 packet_send_debug("%s", msg);
697 auth_debug_reset(void)
700 buffer_clear(&auth_debug);
702 buffer_init(&auth_debug);
710 static struct passwd fake;
712 memset(&fake, 0, sizeof(fake));
713 fake.pw_name = "NOUSER";
715 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
716 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
717 fake.pw_gecos = "NOUSER";
719 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
720 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
721 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS
724 fake.pw_dir = "/nonexist";
725 fake.pw_shell = "/nonexist";
731 * Returns the remote DNS hostname as a string. The returned string must not
732 * be freed. NB. this will usually trigger a DNS query the first time it is
734 * This function does additional checks on the hostname to mitigate some
735 * attacks on legacy rhosts-style authentication.
736 * XXX is RhostsRSAAuthentication vulnerable to these?
737 * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?)
741 remote_hostname(struct ssh *ssh)
743 struct sockaddr_storage from;
745 struct addrinfo hints, *ai, *aitop;
746 char name[NI_MAXHOST], ntop2[NI_MAXHOST];
747 const char *ntop = ssh_remote_ipaddr(ssh);
749 /* Get IP address of client. */
750 fromlen = sizeof(from);
751 memset(&from, 0, sizeof(from));
752 if (getpeername(ssh_packet_get_connection_in(ssh),
753 (struct sockaddr *)&from, &fromlen) < 0) {
754 debug("getpeername failed: %.100s", strerror(errno));
758 ipv64_normalise_mapped(&from, &fromlen);
759 if (from.ss_family == AF_INET6)
760 fromlen = sizeof(struct sockaddr_in6);
762 debug3("Trying to reverse map address %.100s.", ntop);
763 /* Map the IP address to a host name. */
764 if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
765 NULL, 0, NI_NAMEREQD) != 0) {
766 /* Host name not found. Use ip address. */
771 * if reverse lookup result looks like a numeric hostname,
772 * someone is trying to trick us by PTR record like following:
773 * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
775 memset(&hints, 0, sizeof(hints));
776 hints.ai_socktype = SOCK_DGRAM; /*dummy*/
777 hints.ai_flags = AI_NUMERICHOST;
778 if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
779 logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
785 /* Names are stored in lowercase. */
789 * Map it back to an IP address and check that the given
790 * address actually is an address of this host. This is
791 * necessary because anyone with access to a name server can
792 * define arbitrary names for an IP address. Mapping from
793 * name to IP address can be trusted better (but can still be
794 * fooled if the intruder has access to the name server of
797 memset(&hints, 0, sizeof(hints));
798 hints.ai_family = from.ss_family;
799 hints.ai_socktype = SOCK_STREAM;
800 if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
801 logit("reverse mapping checking getaddrinfo for %.700s "
802 "[%s] failed.", name, ntop);
805 /* Look for the address from the list of addresses. */
806 for (ai = aitop; ai; ai = ai->ai_next) {
807 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
808 sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
809 (strcmp(ntop, ntop2) == 0))
813 /* If we reached the end of the list, the address was not there. */
815 /* Address not found for the host name. */
816 logit("Address %.100s maps to %.600s, but this does not "
817 "map back to the address.", ntop, name);
824 * Return the canonical name of the host in the other side of the current
825 * connection. The host name is cached, so it is efficient to call this
830 auth_get_canonical_hostname(struct ssh *ssh, int use_dns)
832 static char *dnsname;
835 return ssh_remote_ipaddr(ssh);
836 else if (dnsname != NULL)
839 dnsname = remote_hostname(ssh);