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djm@openbsd.org76ed2192019-10-16 06:05:39 +00001/* $OpenBSD: auth.c,v 1.142 2019/10/16 06:05:39 djm Exp $ */
Damien Miller116e6df2002-05-22 15:06:28 +10002/*
Ben Lindstrom92a2e382001-03-05 06:59:27 +00003 * Copyright (c) 2000 Markus Friedl. All rights reserved.
Damien Millere4340be2000-09-16 13:29:08 +11004 *
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.
13 *
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.
Damien Millerb38eff82000-04-01 11:09:21 +100024 */
25
26#include "includes.h"
Damien Millerf17883e2006-03-15 11:45:54 +110027
28#include <sys/types.h>
29#include <sys/stat.h>
djm@openbsd.org95767262016-03-07 19:02:43 +000030#include <sys/socket.h>
markus@openbsd.org25cf9102018-01-08 15:21:49 +000031#include <sys/wait.h>
Damien Millerb38eff82000-04-01 11:09:21 +100032
Damien Miller36cbe412006-08-05 12:54:24 +100033#include <netinet/in.h>
34
djm@openbsd.orgbe02d7c2019-09-06 04:53:27 +000035#include <stdlib.h>
Darren Tucker39972492006-07-12 22:22:46 +100036#include <errno.h>
Darren Tucker33c787f2008-07-02 22:37:30 +100037#include <fcntl.h>
Damien Miller03e20032006-03-15 11:16:59 +110038#ifdef HAVE_PATHS_H
Damien Millera9263d02006-03-15 11:18:26 +110039# include <paths.h>
Damien Miller03e20032006-03-15 11:16:59 +110040#endif
Damien Miller9f2abc42006-07-10 20:53:08 +100041#include <pwd.h>
Damien Millerd2c208a2000-05-17 22:00:02 +100042#ifdef HAVE_LOGIN_H
43#include <login.h>
44#endif
Darren Tucker15ee7482004-02-22 09:43:15 +110045#ifdef USE_SHADOW
Damien Miller1f335fb2000-06-26 11:31:33 +100046#include <shadow.h>
Darren Tucker15ee7482004-02-22 09:43:15 +110047#endif
Darren Tucker5d196262006-07-12 22:15:16 +100048#include <stdarg.h>
Damien Millera7a73ee2006-08-05 11:37:59 +100049#include <stdio.h>
Damien Millere3476ed2006-07-24 14:13:33 +100050#include <string.h>
Damien Miller7acf5502008-07-09 20:54:37 +100051#include <unistd.h>
deraadt@openbsd.org087266e2015-01-20 23:14:00 +000052#include <limits.h>
djm@openbsd.org95767262016-03-07 19:02:43 +000053#include <netdb.h>
djm@openbsd.org943d0962019-01-17 04:20:53 +000054#include <time.h>
Ben Lindstrombfb3a0e2001-06-05 20:25:05 +000055
Ben Lindstrom226cfa02001-01-22 05:34:40 +000056#include "xmalloc.h"
57#include "match.h"
58#include "groupaccess.h"
59#include "log.h"
markus@openbsd.orgc7d39ac2018-07-09 21:35:50 +000060#include "sshbuf.h"
Damien Miller7acefbb2014-07-18 14:11:24 +100061#include "misc.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000062#include "servconf.h"
markus@openbsd.orgc7d39ac2018-07-09 21:35:50 +000063#include "sshkey.h"
Damien Millerd7834352006-08-05 12:39:39 +100064#include "hostfile.h"
Damien Millerefb4afe2000-04-12 18:45:05 +100065#include "auth.h"
Ben Lindstromdb65e8f2001-01-19 04:26:52 +000066#include "auth-options.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000067#include "canohost.h"
Ben Lindstrom83647ce2001-06-25 04:30:16 +000068#include "uidswap.h"
Ben Lindstroma574cda2002-05-15 16:16:14 +000069#include "packet.h"
Darren Tucker42d9dc72005-02-02 17:10:11 +110070#include "loginrec.h"
Damien Millerd7834352006-08-05 12:39:39 +100071#ifdef GSSAPI
72#include "ssh-gss.h"
73#endif
Damien Miller1aed65e2010-03-04 21:53:35 +110074#include "authfile.h"
Darren Tucker269a1ea2005-02-03 00:20:53 +110075#include "monitor_wrap.h"
djm@openbsd.org5e39a492014-12-04 02:24:32 +000076#include "ssherr.h"
Darren Tucker0acca372013-06-02 07:41:51 +100077#include "compat.h"
djm@openbsd.org7c856852018-03-03 03:15:51 +000078#include "channels.h"
Damien Millerefb4afe2000-04-12 18:45:05 +100079
Damien Millerb38eff82000-04-01 11:09:21 +100080/* import */
81extern ServerOptions options;
Damien Miller7a8f5b32006-03-31 23:14:23 +110082extern int use_privsep;
Damien Miller120a1ec2018-07-10 19:39:52 +100083extern struct sshbuf *loginmsg;
Damien Miller6433df02006-09-07 10:36:43 +100084extern struct passwd *privsep_pw;
djm@openbsd.org7c856852018-03-03 03:15:51 +000085extern struct sshauthopt *auth_opts;
Damien Millerb38eff82000-04-01 11:09:21 +100086
Ben Lindstroma574cda2002-05-15 16:16:14 +000087/* Debugging messages */
markus@openbsd.orgc7d39ac2018-07-09 21:35:50 +000088static struct sshbuf *auth_debug;
Ben Lindstroma574cda2002-05-15 16:16:14 +000089
Damien Millerb38eff82000-04-01 11:09:21 +100090/*
Kevin Steves7b61cfa2001-01-14 19:11:00 +000091 * Check if the user is allowed to log in via ssh. If user is listed
92 * in DenyUsers or one of user's groups is listed in DenyGroups, false
93 * will be returned. If AllowUsers isn't empty and user isn't listed
94 * there, or if AllowGroups isn't empty and one of user's groups isn't
95 * listed there, false will be returned.
Damien Millerb38eff82000-04-01 11:09:21 +100096 * If the user's shell is not executable, false will be returned.
Damien Miller4af51302000-04-16 11:18:38 +100097 * Otherwise true is returned.
Damien Millerb38eff82000-04-01 11:09:21 +100098 */
Damien Millereba71ba2000-04-29 23:57:08 +100099int
djm@openbsd.org3a00a922019-01-19 21:41:18 +0000100allowed_user(struct ssh *ssh, struct passwd * pw)
Damien Millerb38eff82000-04-01 11:09:21 +1000101{
102 struct stat st;
Darren Tucker43a0dc62003-08-26 14:22:12 +1000103 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
Damien Millereccb9de2005-06-17 12:59:34 +1000104 u_int i;
djm@openbsd.org010359b2016-11-06 05:46:37 +0000105 int r;
Darren Tucker15ee7482004-02-22 09:43:15 +1100106#ifdef USE_SHADOW
Darren Tuckere41bba52003-08-25 11:51:19 +1000107 struct spwd *spw = NULL;
Tim Rice458c6bf2003-01-08 20:04:27 -0800108#endif
Damien Millerb38eff82000-04-01 11:09:21 +1000109
110 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
Kevin Steves7b61cfa2001-01-14 19:11:00 +0000111 if (!pw || !pw->pw_name)
Damien Millerb38eff82000-04-01 11:09:21 +1000112 return 0;
113
Darren Tucker15ee7482004-02-22 09:43:15 +1100114#ifdef USE_SHADOW
Darren Tuckere41bba52003-08-25 11:51:19 +1000115 if (!options.use_pam)
116 spw = getspnam(pw->pw_name);
117#ifdef HAS_SHADOW_EXPIRE
Darren Tucker15ee7482004-02-22 09:43:15 +1100118 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
119 return 0;
Darren Tuckere41bba52003-08-25 11:51:19 +1000120#endif /* HAS_SHADOW_EXPIRE */
Darren Tucker15ee7482004-02-22 09:43:15 +1100121#endif /* USE_SHADOW */
Darren Tuckere41bba52003-08-25 11:51:19 +1000122
Damien Millera8e06ce2003-11-21 23:48:55 +1100123 /* grab passwd field for locked account check */
Damien Miller22989f12008-07-05 08:59:43 +1000124 passwd = pw->pw_passwd;
Darren Tucker15ee7482004-02-22 09:43:15 +1100125#ifdef USE_SHADOW
Darren Tuckere41bba52003-08-25 11:51:19 +1000126 if (spw != NULL)
Tim Rice99203ec2007-03-26 09:35:28 -0700127#ifdef USE_LIBIAF
Tim Rice2291c002005-08-26 13:15:19 -0700128 passwd = get_iaf_password(pw);
129#else
Darren Tuckere41bba52003-08-25 11:51:19 +1000130 passwd = spw->sp_pwdp;
Tim Rice99203ec2007-03-26 09:35:28 -0700131#endif /* USE_LIBIAF */
Damien Miller06817f92003-01-07 23:55:59 +1100132#endif
133
Damien Millera8e06ce2003-11-21 23:48:55 +1100134 /* check for locked account */
Darren Tucker43a0dc62003-08-26 14:22:12 +1000135 if (!options.use_pam && passwd && *passwd) {
Darren Tuckere41bba52003-08-25 11:51:19 +1000136 int locked = 0;
137
138#ifdef LOCKED_PASSWD_STRING
139 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
140 locked = 1;
141#endif
142#ifdef LOCKED_PASSWD_PREFIX
143 if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
144 strlen(LOCKED_PASSWD_PREFIX)) == 0)
145 locked = 1;
146#endif
147#ifdef LOCKED_PASSWD_SUBSTR
148 if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
149 locked = 1;
150#endif
Tim Rice99203ec2007-03-26 09:35:28 -0700151#ifdef USE_LIBIAF
Tim Ricead7d5472010-08-12 10:33:01 -0700152 free((void *) passwd);
Tim Rice99203ec2007-03-26 09:35:28 -0700153#endif /* USE_LIBIAF */
Darren Tuckere41bba52003-08-25 11:51:19 +1000154 if (locked) {
155 logit("User %.100s not allowed because account is locked",
156 pw->pw_name);
157 return 0;
158 }
159 }
160
Damien Milleref7df542000-05-19 00:03:23 +1000161 /*
Damien Miller47cf16b2010-02-12 09:25:29 +1100162 * Deny if shell does not exist or is not executable unless we
163 * are chrooting.
Damien Milleref7df542000-05-19 00:03:23 +1000164 */
Damien Miller47cf16b2010-02-12 09:25:29 +1100165 if (options.chroot_directory == NULL ||
166 strcasecmp(options.chroot_directory, "none") == 0) {
167 char *shell = xstrdup((pw->pw_shell[0] == '\0') ?
168 _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */
Darren Tucker94881d82010-01-15 11:44:46 +1100169
deraadt@openbsd.org4d28fa72019-06-28 13:35:04 +0000170 if (stat(shell, &st) == -1) {
Damien Miller47cf16b2010-02-12 09:25:29 +1100171 logit("User %.100s not allowed because shell %.100s "
172 "does not exist", pw->pw_name, shell);
Darren Tuckera627d422013-06-02 07:31:17 +1000173 free(shell);
Damien Miller47cf16b2010-02-12 09:25:29 +1100174 return 0;
175 }
176 if (S_ISREG(st.st_mode) == 0 ||
177 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
178 logit("User %.100s not allowed because shell %.100s "
179 "is not executable", pw->pw_name, shell);
Darren Tuckera627d422013-06-02 07:31:17 +1000180 free(shell);
Damien Miller47cf16b2010-02-12 09:25:29 +1100181 return 0;
182 }
Darren Tuckera627d422013-06-02 07:31:17 +1000183 free(shell);
Darren Tucker94881d82010-01-15 11:44:46 +1100184 }
Damien Milleref7df542000-05-19 00:03:23 +1000185
Darren Tuckera8f553d2005-03-14 23:17:27 +1100186 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
187 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
djm@openbsd.org95767262016-03-07 19:02:43 +0000188 hostname = auth_get_canonical_hostname(ssh, options.use_dns);
189 ipaddr = ssh_remote_ipaddr(ssh);
Ben Lindstrom3fb5d002002-03-05 01:42:42 +0000190 }
191
Damien Millerb38eff82000-04-01 11:09:21 +1000192 /* Return false if user is listed in DenyUsers */
193 if (options.num_deny_users > 0) {
dtucker@openbsd.orgfe06b682016-12-15 21:29:05 +0000194 for (i = 0; i < options.num_deny_users; i++) {
djm@openbsd.org010359b2016-11-06 05:46:37 +0000195 r = match_user(pw->pw_name, hostname, ipaddr,
196 options.deny_users[i]);
197 if (r < 0) {
198 fatal("Invalid DenyUsers pattern \"%.100s\"",
199 options.deny_users[i]);
djm@openbsd.org1a6f9d22016-11-08 22:04:34 +0000200 } else if (r != 0) {
Darren Tucker094cd0b2005-01-24 21:56:48 +1100201 logit("User %.100s from %.100s not allowed "
202 "because listed in DenyUsers",
203 pw->pw_name, hostname);
Damien Millerb38eff82000-04-01 11:09:21 +1000204 return 0;
Ben Lindstrom6ef9ec62002-03-05 01:40:37 +0000205 }
dtucker@openbsd.orgfe06b682016-12-15 21:29:05 +0000206 }
Damien Millerb38eff82000-04-01 11:09:21 +1000207 }
208 /* Return false if AllowUsers isn't empty and user isn't listed there */
209 if (options.num_allow_users > 0) {
djm@openbsd.org010359b2016-11-06 05:46:37 +0000210 for (i = 0; i < options.num_allow_users; i++) {
211 r = match_user(pw->pw_name, hostname, ipaddr,
212 options.allow_users[i]);
213 if (r < 0) {
214 fatal("Invalid AllowUsers pattern \"%.100s\"",
215 options.allow_users[i]);
216 } else if (r == 1)
Damien Millerb38eff82000-04-01 11:09:21 +1000217 break;
djm@openbsd.org010359b2016-11-06 05:46:37 +0000218 }
Damien Millerb38eff82000-04-01 11:09:21 +1000219 /* i < options.num_allow_users iff we break for loop */
Ben Lindstrom6ef9ec62002-03-05 01:40:37 +0000220 if (i >= options.num_allow_users) {
Darren Tucker094cd0b2005-01-24 21:56:48 +1100221 logit("User %.100s from %.100s not allowed because "
222 "not listed in AllowUsers", pw->pw_name, hostname);
Damien Millerb38eff82000-04-01 11:09:21 +1000223 return 0;
Ben Lindstrom6ef9ec62002-03-05 01:40:37 +0000224 }
Damien Millerb38eff82000-04-01 11:09:21 +1000225 }
Damien Millerb38eff82000-04-01 11:09:21 +1000226 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
Kevin Steves7b61cfa2001-01-14 19:11:00 +0000227 /* Get the user's group access list (primary and supplementary) */
Ben Lindstrom6ef9ec62002-03-05 01:40:37 +0000228 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
Darren Tucker094cd0b2005-01-24 21:56:48 +1100229 logit("User %.100s from %.100s not allowed because "
230 "not in any group", pw->pw_name, hostname);
Damien Millerb38eff82000-04-01 11:09:21 +1000231 return 0;
Ben Lindstrom6ef9ec62002-03-05 01:40:37 +0000232 }
Damien Millerb38eff82000-04-01 11:09:21 +1000233
Kevin Steves7b61cfa2001-01-14 19:11:00 +0000234 /* Return false if one of user's groups is listed in DenyGroups */
235 if (options.num_deny_groups > 0)
236 if (ga_match(options.deny_groups,
237 options.num_deny_groups)) {
238 ga_free();
Darren Tucker094cd0b2005-01-24 21:56:48 +1100239 logit("User %.100s from %.100s not allowed "
240 "because a group is listed in DenyGroups",
241 pw->pw_name, hostname);
Damien Millerb38eff82000-04-01 11:09:21 +1000242 return 0;
Kevin Steves7b61cfa2001-01-14 19:11:00 +0000243 }
Damien Millerb38eff82000-04-01 11:09:21 +1000244 /*
Kevin Steves7b61cfa2001-01-14 19:11:00 +0000245 * Return false if AllowGroups isn't empty and one of user's groups
Damien Millerb38eff82000-04-01 11:09:21 +1000246 * isn't listed there
247 */
Kevin Steves7b61cfa2001-01-14 19:11:00 +0000248 if (options.num_allow_groups > 0)
249 if (!ga_match(options.allow_groups,
250 options.num_allow_groups)) {
251 ga_free();
Darren Tucker094cd0b2005-01-24 21:56:48 +1100252 logit("User %.100s from %.100s not allowed "
253 "because none of user's groups are listed "
254 "in AllowGroups", pw->pw_name, hostname);
Damien Millerb38eff82000-04-01 11:09:21 +1000255 return 0;
Kevin Steves7b61cfa2001-01-14 19:11:00 +0000256 }
257 ga_free();
Damien Millerb38eff82000-04-01 11:09:21 +1000258 }
259
Darren Tucker0a9d43d2004-06-23 13:45:24 +1000260#ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
Kevin Adlera784fa82018-12-12 22:12:45 -0600261 if (!sys_auth_allowed_user(pw, loginmsg))
Darren Tucker0a9d43d2004-06-23 13:45:24 +1000262 return 0;
263#endif
Damien Millerb38eff82000-04-01 11:09:21 +1000264
265 /* We found no reason not to let this user try to log on... */
266 return 1;
267}
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000268
djm@openbsd.org8f574952017-06-24 06:34:38 +0000269/*
270 * Formats any key left in authctxt->auth_method_key for inclusion in
271 * auth_log()'s message. Also includes authxtct->auth_method_info if present.
272 */
273static char *
274format_method_key(Authctxt *authctxt)
Darren Tucker0acca372013-06-02 07:41:51 +1000275{
djm@openbsd.org8f574952017-06-24 06:34:38 +0000276 const struct sshkey *key = authctxt->auth_method_key;
277 const char *methinfo = authctxt->auth_method_info;
djm@openbsd.org50e26872018-09-12 01:19:12 +0000278 char *fp, *cafp, *ret = NULL;
Darren Tucker0acca372013-06-02 07:41:51 +1000279
djm@openbsd.org8f574952017-06-24 06:34:38 +0000280 if (key == NULL)
281 return NULL;
Darren Tucker0acca372013-06-02 07:41:51 +1000282
markus@openbsd.orgc7d39ac2018-07-09 21:35:50 +0000283 if (sshkey_is_cert(key)) {
djm@openbsd.org50e26872018-09-12 01:19:12 +0000284 fp = sshkey_fingerprint(key,
djm@openbsd.org8f574952017-06-24 06:34:38 +0000285 options.fingerprint_hash, SSH_FP_DEFAULT);
djm@openbsd.org50e26872018-09-12 01:19:12 +0000286 cafp = sshkey_fingerprint(key->cert->signature_key,
287 options.fingerprint_hash, SSH_FP_DEFAULT);
288 xasprintf(&ret, "%s %s ID %s (serial %llu) CA %s %s%s%s",
289 sshkey_type(key), fp == NULL ? "(null)" : fp,
290 key->cert->key_id,
djm@openbsd.org8f574952017-06-24 06:34:38 +0000291 (unsigned long long)key->cert->serial,
292 sshkey_type(key->cert->signature_key),
djm@openbsd.org50e26872018-09-12 01:19:12 +0000293 cafp == NULL ? "(null)" : cafp,
djm@openbsd.org8f574952017-06-24 06:34:38 +0000294 methinfo == NULL ? "" : ", ",
295 methinfo == NULL ? "" : methinfo);
296 free(fp);
djm@openbsd.org50e26872018-09-12 01:19:12 +0000297 free(cafp);
djm@openbsd.org8f574952017-06-24 06:34:38 +0000298 } else {
299 fp = sshkey_fingerprint(key, options.fingerprint_hash,
300 SSH_FP_DEFAULT);
301 xasprintf(&ret, "%s %s%s%s", sshkey_type(key),
302 fp == NULL ? "(null)" : fp,
303 methinfo == NULL ? "" : ", ",
304 methinfo == NULL ? "" : methinfo);
305 free(fp);
306 }
307 return ret;
Darren Tucker0acca372013-06-02 07:41:51 +1000308}
309
310void
djm@openbsd.org3a00a922019-01-19 21:41:18 +0000311auth_log(struct ssh *ssh, int authenticated, int partial,
Darren Tucker0acca372013-06-02 07:41:51 +1000312 const char *method, const char *submethod)
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000313{
djm@openbsd.org3a00a922019-01-19 21:41:18 +0000314 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
djm@openbsd.org50e26872018-09-12 01:19:12 +0000315 int level = SYSLOG_LEVEL_VERBOSE;
djm@openbsd.org8f574952017-06-24 06:34:38 +0000316 const char *authmsg;
317 char *extra = NULL;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000318
Damien Miller7a8f5b32006-03-31 23:14:23 +1100319 if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
320 return;
321
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000322 /* Raise logging level */
323 if (authenticated == 1 ||
324 !authctxt->valid ||
Darren Tucker89413db2004-05-24 10:36:23 +1000325 authctxt->failures >= options.max_authtries / 2 ||
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000326 strcmp(method, "password") == 0)
djm@openbsd.org50e26872018-09-12 01:19:12 +0000327 level = SYSLOG_LEVEL_INFO;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000328
329 if (authctxt->postponed)
330 authmsg = "Postponed";
Damien Miller15b05cf2012-12-03 09:53:20 +1100331 else if (partial)
332 authmsg = "Partial";
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000333 else
334 authmsg = authenticated ? "Accepted" : "Failed";
335
djm@openbsd.org8f574952017-06-24 06:34:38 +0000336 if ((extra = format_method_key(authctxt)) == NULL) {
337 if (authctxt->auth_method_info != NULL)
338 extra = xstrdup(authctxt->auth_method_info);
339 }
340
djm@openbsd.org50e26872018-09-12 01:19:12 +0000341 do_log2(level, "%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s",
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000342 authmsg,
343 method,
Damien Miller15b05cf2012-12-03 09:53:20 +1100344 submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod,
Darren Tucker5cb30ad2004-08-12 22:40:24 +1000345 authctxt->valid ? "" : "invalid user ",
Damien Millerf6552072001-11-12 11:06:06 +1100346 authctxt->user,
djm@openbsd.org95767262016-03-07 19:02:43 +0000347 ssh_remote_ipaddr(ssh),
348 ssh_remote_port(ssh),
djm@openbsd.org8f574952017-06-24 06:34:38 +0000349 extra != NULL ? ": " : "",
350 extra != NULL ? extra : "");
351
352 free(extra);
Ben Lindstrome06eb682002-07-04 00:27:21 +0000353
Darren Tucker97363a82003-05-02 23:42:25 +1000354#ifdef CUSTOM_FAILED_LOGIN
Darren Tucker2fba9932005-02-02 23:30:24 +1100355 if (authenticated == 0 && !authctxt->postponed &&
356 (strcmp(method, "password") == 0 ||
Darren Tucker40d9a632005-02-04 15:19:44 +1100357 strncmp(method, "keyboard-interactive", 20) == 0 ||
358 strcmp(method, "challenge-response") == 0))
Damien Miller08f66d92019-01-20 09:58:45 +1100359 record_failed_login(ssh, authctxt->user,
Darren Tucker885fb2a2016-03-08 11:58:43 +1100360 auth_get_canonical_hostname(ssh, options.use_dns), "ssh");
Darren Tucker26d4e192006-08-30 22:33:09 +1000361# ifdef WITH_AIXAUTHENTICATE
362 if (authenticated)
Darren Tucker79a87d32019-04-03 06:27:45 +1100363 sys_auth_record_login(authctxt->user,
Darren Tucker885fb2a2016-03-08 11:58:43 +1100364 auth_get_canonical_hostname(ssh, options.use_dns), "ssh",
Kevin Adlera784fa82018-12-12 22:12:45 -0600365 loginmsg);
Darren Tucker26d4e192006-08-30 22:33:09 +1000366# endif
Darren Tucker97363a82003-05-02 23:42:25 +1000367#endif
Darren Tucker2e0cf0d2005-02-08 21:52:47 +1100368#ifdef SSH_AUDIT_EVENTS
Darren Tuckerf14b2aa2006-05-21 18:26:40 +1000369 if (authenticated == 0 && !authctxt->postponed)
Damien Miller9b655dc2019-01-20 14:55:27 +1100370 audit_event(ssh, audit_classify_auth(method));
Darren Tucker269a1ea2005-02-03 00:20:53 +1100371#endif
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000372}
373
Damien Miller686feb52014-07-03 21:29:38 +1000374
375void
djm@openbsd.org3a00a922019-01-19 21:41:18 +0000376auth_maxtries_exceeded(struct ssh *ssh)
Damien Miller686feb52014-07-03 21:29:38 +1000377{
djm@openbsd.org3a00a922019-01-19 21:41:18 +0000378 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
djm@openbsd.org95767262016-03-07 19:02:43 +0000379
djm@openbsd.org6f621602015-02-25 17:29:38 +0000380 error("maximum authentication attempts exceeded for "
markus@openbsd.org6cb6dcf2016-08-13 17:47:40 +0000381 "%s%.100s from %.200s port %d ssh2",
Damien Miller686feb52014-07-03 21:29:38 +1000382 authctxt->valid ? "" : "invalid user ",
383 authctxt->user,
djm@openbsd.org95767262016-03-07 19:02:43 +0000384 ssh_remote_ipaddr(ssh),
markus@openbsd.org6cb6dcf2016-08-13 17:47:40 +0000385 ssh_remote_port(ssh));
djm@openbsd.org3a00a922019-01-19 21:41:18 +0000386 ssh_packet_disconnect(ssh, "Too many authentication failures");
Damien Miller686feb52014-07-03 21:29:38 +1000387 /* NOTREACHED */
388}
389
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000390/*
Ben Lindstromd8a90212001-02-15 03:08:27 +0000391 * Check whether root logins are disallowed.
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000392 */
393int
djm@openbsd.org7c856852018-03-03 03:15:51 +0000394auth_root_allowed(struct ssh *ssh, const char *method)
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000395{
Ben Lindstromd8a90212001-02-15 03:08:27 +0000396 switch (options.permit_root_login) {
397 case PERMIT_YES:
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000398 return 1;
Ben Lindstromd8a90212001-02-15 03:08:27 +0000399 case PERMIT_NO_PASSWD:
deraadt@openbsd.org1dc8d932015-08-06 14:53:21 +0000400 if (strcmp(method, "publickey") == 0 ||
401 strcmp(method, "hostbased") == 0 ||
djm@openbsd.org32a18192015-08-21 03:42:19 +0000402 strcmp(method, "gssapi-with-mic") == 0)
Ben Lindstromd8a90212001-02-15 03:08:27 +0000403 return 1;
404 break;
405 case PERMIT_FORCED_ONLY:
djm@openbsd.org7c856852018-03-03 03:15:51 +0000406 if (auth_opts->force_command != NULL) {
Damien Miller996acd22003-04-09 20:59:48 +1000407 logit("Root login accepted for forced command.");
Ben Lindstromd8a90212001-02-15 03:08:27 +0000408 return 1;
409 }
410 break;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000411 }
djm@openbsd.org95767262016-03-07 19:02:43 +0000412 logit("ROOT LOGIN REFUSED FROM %.200s port %d",
413 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
Ben Lindstromd8a90212001-02-15 03:08:27 +0000414 return 0;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000415}
Ben Lindstrombfb3a0e2001-06-05 20:25:05 +0000416
417
418/*
419 * Given a template and a passwd structure, build a filename
420 * by substituting % tokenised options. Currently, %% becomes '%',
421 * %h becomes the home directory and %u the username.
422 *
423 * This returns a buffer allocated by xmalloc.
424 */
Damien Millerd8478b62011-05-29 21:39:36 +1000425char *
Damien Miller6476cad2005-06-16 13:18:34 +1000426expand_authorized_keys(const char *filename, struct passwd *pw)
Ben Lindstrombfb3a0e2001-06-05 20:25:05 +0000427{
djm@openbsd.org9c935dd2018-06-01 03:33:53 +0000428 char *file, uidstr[32], ret[PATH_MAX];
Damien Miller07d86be2006-03-26 14:19:21 +1100429 int i;
Ben Lindstrombfb3a0e2001-06-05 20:25:05 +0000430
djm@openbsd.org9c935dd2018-06-01 03:33:53 +0000431 snprintf(uidstr, sizeof(uidstr), "%llu",
432 (unsigned long long)pw->pw_uid);
Damien Miller6476cad2005-06-16 13:18:34 +1000433 file = percent_expand(filename, "h", pw->pw_dir,
djm@openbsd.org9c935dd2018-06-01 03:33:53 +0000434 "u", pw->pw_name, "U", uidstr, (char *)NULL);
Ben Lindstrombfb3a0e2001-06-05 20:25:05 +0000435
436 /*
437 * Ensure that filename starts anchored. If not, be backward
438 * compatible and prepend the '%h/'
439 */
djm@openbsd.org2a358622018-11-16 03:26:01 +0000440 if (path_absolute(file))
Damien Miller6476cad2005-06-16 13:18:34 +1000441 return (file);
Ben Lindstrombfb3a0e2001-06-05 20:25:05 +0000442
Damien Miller07d86be2006-03-26 14:19:21 +1100443 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
444 if (i < 0 || (size_t)i >= sizeof(ret))
Damien Miller6476cad2005-06-16 13:18:34 +1000445 fatal("expand_authorized_keys: path too long");
Darren Tuckera627d422013-06-02 07:31:17 +1000446 free(file);
Damien Miller07d86be2006-03-26 14:19:21 +1100447 return (xstrdup(ret));
Ben Lindstrombfb3a0e2001-06-05 20:25:05 +0000448}
449
450char *
Damien Miller30da3442010-05-10 11:58:03 +1000451authorized_principals_file(struct passwd *pw)
452{
djm@openbsd.org7e8528c2015-05-01 04:17:51 +0000453 if (options.authorized_principals_file == NULL)
Damien Miller30da3442010-05-10 11:58:03 +1000454 return NULL;
455 return expand_authorized_keys(options.authorized_principals_file, pw);
456}
457
Ben Lindstrom83647ce2001-06-25 04:30:16 +0000458/* return ok if key exists in sysfile or userfile */
459HostStatus
markus@openbsd.org54d90ac2017-05-30 08:52:19 +0000460check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host,
Ben Lindstrom83647ce2001-06-25 04:30:16 +0000461 const char *sysfile, const char *userfile)
462{
Ben Lindstrom83647ce2001-06-25 04:30:16 +0000463 char *user_hostfile;
464 struct stat st;
Ben Lindstrom65366a82001-12-06 16:32:47 +0000465 HostStatus host_status;
Damien Millerd925dcd2010-12-01 12:21:51 +1100466 struct hostkeys *hostkeys;
467 const struct hostkey_entry *found;
Ben Lindstrom83647ce2001-06-25 04:30:16 +0000468
Damien Millerd925dcd2010-12-01 12:21:51 +1100469 hostkeys = init_hostkeys();
470 load_hostkeys(hostkeys, host, sysfile);
471 if (userfile != NULL) {
Ben Lindstrom83647ce2001-06-25 04:30:16 +0000472 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
473 if (options.strict_modes &&
474 (stat(user_hostfile, &st) == 0) &&
475 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
Damien Miller9f0f5c62001-12-21 14:45:46 +1100476 (st.st_mode & 022) != 0)) {
Damien Miller996acd22003-04-09 20:59:48 +1000477 logit("Authentication refused for %.100s: "
Ben Lindstrom83647ce2001-06-25 04:30:16 +0000478 "bad owner or modes for %.200s",
479 pw->pw_name, user_hostfile);
Damien Miller48147d62010-06-26 09:39:25 +1000480 auth_debug_add("Ignored %.200s: bad ownership or modes",
481 user_hostfile);
Ben Lindstrom83647ce2001-06-25 04:30:16 +0000482 } else {
483 temporarily_use_uid(pw);
Damien Millerd925dcd2010-12-01 12:21:51 +1100484 load_hostkeys(hostkeys, host, user_hostfile);
Ben Lindstrom83647ce2001-06-25 04:30:16 +0000485 restore_uid();
486 }
Darren Tuckera627d422013-06-02 07:31:17 +1000487 free(user_hostfile);
Ben Lindstrom83647ce2001-06-25 04:30:16 +0000488 }
Damien Millerd925dcd2010-12-01 12:21:51 +1100489 host_status = check_key_in_hostkeys(hostkeys, key, &found);
490 if (host_status == HOST_REVOKED)
491 error("WARNING: revoked key for %s attempted authentication",
djm@openbsd.org76ed2192019-10-16 06:05:39 +0000492 host);
Damien Millerd925dcd2010-12-01 12:21:51 +1100493 else if (host_status == HOST_OK)
494 debug("%s: key for %s found at %s:%ld", __func__,
495 found->host, found->file, found->line);
496 else
497 debug("%s: key for host %s not found", __func__, host);
Ben Lindstrom83647ce2001-06-25 04:30:16 +0000498
Damien Millerd925dcd2010-12-01 12:21:51 +1100499 free_hostkeys(hostkeys);
500
Ben Lindstrom83647ce2001-06-25 04:30:16 +0000501 return host_status;
502}
503
Damien Miller30da3442010-05-10 11:58:03 +1000504static FILE *
505auth_openfile(const char *file, struct passwd *pw, int strict_modes,
506 int log_missing, char *file_type)
Darren Tucker33c787f2008-07-02 22:37:30 +1000507{
508 char line[1024];
509 struct stat st;
510 int fd;
511 FILE *f;
512
Darren Tucker43551522010-01-10 19:27:17 +1100513 if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) {
Damien Miller30da3442010-05-10 11:58:03 +1000514 if (log_missing || errno != ENOENT)
515 debug("Could not open %s '%s': %s", file_type, file,
Darren Tucker43551522010-01-10 19:27:17 +1100516 strerror(errno));
Darren Tucker33c787f2008-07-02 22:37:30 +1000517 return NULL;
Darren Tucker43551522010-01-10 19:27:17 +1100518 }
Darren Tucker33c787f2008-07-02 22:37:30 +1000519
deraadt@openbsd.org4d28fa72019-06-28 13:35:04 +0000520 if (fstat(fd, &st) == -1) {
Darren Tucker33c787f2008-07-02 22:37:30 +1000521 close(fd);
522 return NULL;
523 }
524 if (!S_ISREG(st.st_mode)) {
Damien Miller30da3442010-05-10 11:58:03 +1000525 logit("User %s %s %s is not a regular file",
526 pw->pw_name, file_type, file);
Darren Tucker33c787f2008-07-02 22:37:30 +1000527 close(fd);
528 return NULL;
529 }
530 unset_nonblock(fd);
531 if ((f = fdopen(fd, "r")) == NULL) {
532 close(fd);
533 return NULL;
534 }
Damien Miller6a740e72010-12-01 12:01:51 +1100535 if (strict_modes &&
djm@openbsd.orgde4ae072017-08-18 05:36:45 +0000536 safe_path_fd(fileno(f), file, pw, line, sizeof(line)) != 0) {
Darren Tucker33c787f2008-07-02 22:37:30 +1000537 fclose(f);
538 logit("Authentication refused: %s", line);
Damien Miller48147d62010-06-26 09:39:25 +1000539 auth_debug_add("Ignored %s: %s", file_type, line);
Darren Tucker33c787f2008-07-02 22:37:30 +1000540 return NULL;
541 }
542
543 return f;
544}
545
Damien Miller30da3442010-05-10 11:58:03 +1000546
547FILE *
548auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
549{
550 return auth_openfile(file, pw, strict_modes, 1, "authorized keys");
551}
552
553FILE *
554auth_openprincipals(const char *file, struct passwd *pw, int strict_modes)
555{
556 return auth_openfile(file, pw, strict_modes, 0,
557 "authorized principals");
558}
559
Ben Lindstrom2ae18f42002-03-22 01:24:38 +0000560struct passwd *
djm@openbsd.org3a00a922019-01-19 21:41:18 +0000561getpwnamallow(struct ssh *ssh, const char *user)
Ben Lindstrom2ae18f42002-03-22 01:24:38 +0000562{
Ben Lindstromb481e132002-03-22 01:35:47 +0000563#ifdef HAVE_LOGIN_CAP
564 extern login_cap_t *lc;
565#ifdef BSD_AUTH
566 auth_session_t *as;
567#endif
568#endif
Ben Lindstrom2ae18f42002-03-22 01:24:38 +0000569 struct passwd *pw;
djm@openbsd.org172a5922019-01-19 21:37:48 +0000570 struct connection_info *ci;
Ben Lindstrom2ae18f42002-03-22 01:24:38 +0000571
djm@openbsd.org172a5922019-01-19 21:37:48 +0000572 ci = get_connection_info(ssh, 1, options.use_dns);
Darren Tuckerfbcf8272012-05-19 19:37:01 +1000573 ci->user = user;
574 parse_server_match_config(&options, ci);
djm@openbsd.org54cd41a2017-05-17 01:24:17 +0000575 log_change_level(options.log_level);
djm@openbsd.orgdbee4112017-09-12 06:32:07 +0000576 process_permitopen(ssh, &options);
Darren Tucker45150472006-07-12 22:34:17 +1000577
Darren Tuckerb3d20a32010-03-07 11:56:59 +1100578#if defined(_AIX) && defined(HAVE_SETAUTHDB)
579 aix_setauthdb(user);
580#endif
581
Ben Lindstrom2ae18f42002-03-22 01:24:38 +0000582 pw = getpwnam(user);
Darren Tuckerb3d20a32010-03-07 11:56:59 +1100583
584#if defined(_AIX) && defined(HAVE_SETAUTHDB)
585 aix_restoreauthdb();
586#endif
Damien Miller6f0a1882002-09-22 01:26:51 +1000587 if (pw == NULL) {
djm@openbsd.org95767262016-03-07 19:02:43 +0000588 logit("Invalid user %.100s from %.100s port %d",
589 user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
Darren Tucker97363a82003-05-02 23:42:25 +1000590#ifdef CUSTOM_FAILED_LOGIN
Damien Miller08f66d92019-01-20 09:58:45 +1100591 record_failed_login(ssh, user,
Darren Tucker885fb2a2016-03-08 11:58:43 +1100592 auth_get_canonical_hostname(ssh, options.use_dns), "ssh");
Ben Lindstromf5397c02002-11-09 16:11:10 +0000593#endif
Darren Tucker2e0cf0d2005-02-08 21:52:47 +1100594#ifdef SSH_AUDIT_EVENTS
Damien Miller9b655dc2019-01-20 14:55:27 +1100595 audit_event(ssh, SSH_INVALID_USER);
Darren Tucker2e0cf0d2005-02-08 21:52:47 +1100596#endif /* SSH_AUDIT_EVENTS */
Damien Miller6f0a1882002-09-22 01:26:51 +1000597 return (NULL);
598 }
djm@openbsd.org3a00a922019-01-19 21:41:18 +0000599 if (!allowed_user(ssh, pw))
Ben Lindstromb481e132002-03-22 01:35:47 +0000600 return (NULL);
601#ifdef HAVE_LOGIN_CAP
602 if ((lc = login_getclass(pw->pw_class)) == NULL) {
603 debug("unable to get login class: %s", user);
604 return (NULL);
605 }
606#ifdef BSD_AUTH
607 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
Damien Miller13e35a02002-05-22 14:04:11 +1000608 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
Ben Lindstromb481e132002-03-22 01:35:47 +0000609 debug("Approval failure for %s", user);
Ben Lindstrom2ae18f42002-03-22 01:24:38 +0000610 pw = NULL;
Ben Lindstromb481e132002-03-22 01:35:47 +0000611 }
612 if (as != NULL)
613 auth_close(as);
614#endif
615#endif
Ben Lindstromf34e4eb2002-03-22 03:08:30 +0000616 if (pw != NULL)
617 return (pwcopy(pw));
618 return (NULL);
Ben Lindstrom2ae18f42002-03-22 01:24:38 +0000619}
Ben Lindstroma574cda2002-05-15 16:16:14 +0000620
Damien Miller1aed65e2010-03-04 21:53:35 +1100621/* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
622int
markus@openbsd.org54d90ac2017-05-30 08:52:19 +0000623auth_key_is_revoked(struct sshkey *key)
Damien Miller1aed65e2010-03-04 21:53:35 +1100624{
djm@openbsd.org5e39a492014-12-04 02:24:32 +0000625 char *fp = NULL;
626 int r;
Damien Miller1aed65e2010-03-04 21:53:35 +1100627
628 if (options.revoked_keys_file == NULL)
629 return 0;
djm@openbsd.org56d1c832014-12-21 22:27:55 +0000630 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
631 SSH_FP_DEFAULT)) == NULL) {
djm@openbsd.org5e39a492014-12-04 02:24:32 +0000632 r = SSH_ERR_ALLOC_FAIL;
633 error("%s: fingerprint key: %s", __func__, ssh_err(r));
634 goto out;
635 }
636
637 r = sshkey_check_revoked(key, options.revoked_keys_file);
638 switch (r) {
Damien Millerf3747bf2013-01-18 11:44:04 +1100639 case 0:
djm@openbsd.org5e39a492014-12-04 02:24:32 +0000640 break; /* not revoked */
641 case SSH_ERR_KEY_REVOKED:
642 error("Authentication key %s %s revoked by file %s",
643 sshkey_type(key), fp, options.revoked_keys_file);
644 goto out;
Damien Millerf3747bf2013-01-18 11:44:04 +1100645 default:
djm@openbsd.org5e39a492014-12-04 02:24:32 +0000646 error("Error checking authentication key %s %s in "
647 "revoked keys file %s: %s", sshkey_type(key), fp,
648 options.revoked_keys_file, ssh_err(r));
649 goto out;
Damien Millerf3747bf2013-01-18 11:44:04 +1100650 }
djm@openbsd.org5e39a492014-12-04 02:24:32 +0000651
652 /* Success */
653 r = 0;
654
655 out:
656 free(fp);
657 return r == 0 ? 0 : 1;
Damien Miller1aed65e2010-03-04 21:53:35 +1100658}
659
Ben Lindstroma574cda2002-05-15 16:16:14 +0000660void
661auth_debug_add(const char *fmt,...)
662{
663 char buf[1024];
664 va_list args;
markus@openbsd.orgc7d39ac2018-07-09 21:35:50 +0000665 int r;
Ben Lindstroma574cda2002-05-15 16:16:14 +0000666
markus@openbsd.orgc7d39ac2018-07-09 21:35:50 +0000667 if (auth_debug == NULL)
Ben Lindstroma574cda2002-05-15 16:16:14 +0000668 return;
669
670 va_start(args, fmt);
671 vsnprintf(buf, sizeof(buf), fmt, args);
672 va_end(args);
markus@openbsd.orgc7d39ac2018-07-09 21:35:50 +0000673 if ((r = sshbuf_put_cstring(auth_debug, buf)) != 0)
674 fatal("%s: sshbuf_put_cstring: %s", __func__, ssh_err(r));
Ben Lindstroma574cda2002-05-15 16:16:14 +0000675}
676
677void
djm@openbsd.org3a00a922019-01-19 21:41:18 +0000678auth_debug_send(struct ssh *ssh)
Ben Lindstroma574cda2002-05-15 16:16:14 +0000679{
680 char *msg;
markus@openbsd.orgc7d39ac2018-07-09 21:35:50 +0000681 int r;
Ben Lindstroma574cda2002-05-15 16:16:14 +0000682
markus@openbsd.orgc7d39ac2018-07-09 21:35:50 +0000683 if (auth_debug == NULL)
Ben Lindstroma574cda2002-05-15 16:16:14 +0000684 return;
markus@openbsd.orgc7d39ac2018-07-09 21:35:50 +0000685 while (sshbuf_len(auth_debug) != 0) {
686 if ((r = sshbuf_get_cstring(auth_debug, &msg, NULL)) != 0)
687 fatal("%s: sshbuf_get_cstring: %s",
688 __func__, ssh_err(r));
689 ssh_packet_send_debug(ssh, "%s", msg);
Darren Tuckera627d422013-06-02 07:31:17 +1000690 free(msg);
Ben Lindstroma574cda2002-05-15 16:16:14 +0000691 }
692}
693
694void
695auth_debug_reset(void)
696{
markus@openbsd.orgc7d39ac2018-07-09 21:35:50 +0000697 if (auth_debug != NULL)
698 sshbuf_reset(auth_debug);
699 else if ((auth_debug = sshbuf_new()) == NULL)
700 fatal("%s: sshbuf_new failed", __func__);
Ben Lindstroma574cda2002-05-15 16:16:14 +0000701}
Damien Miller856f0be2003-09-03 07:32:45 +1000702
703struct passwd *
704fakepw(void)
705{
706 static struct passwd fake;
707
708 memset(&fake, 0, sizeof(fake));
709 fake.pw_name = "NOUSER";
710 fake.pw_passwd =
Damien Miller787b2ec2003-11-21 23:56:47 +1100711 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
Damien Miller6332da22013-04-23 14:25:52 +1000712#ifdef HAVE_STRUCT_PASSWD_PW_GECOS
Damien Miller856f0be2003-09-03 07:32:45 +1000713 fake.pw_gecos = "NOUSER";
Damien Miller6332da22013-04-23 14:25:52 +1000714#endif
Damien Miller143c2ef2006-12-05 09:08:54 +1100715 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
716 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
Damien Miller6332da22013-04-23 14:25:52 +1000717#ifdef HAVE_STRUCT_PASSWD_PW_CLASS
Damien Miller856f0be2003-09-03 07:32:45 +1000718 fake.pw_class = "";
719#endif
720 fake.pw_dir = "/nonexist";
721 fake.pw_shell = "/nonexist";
722
723 return (&fake);
724}
djm@openbsd.org95767262016-03-07 19:02:43 +0000725
726/*
727 * Returns the remote DNS hostname as a string. The returned string must not
728 * be freed. NB. this will usually trigger a DNS query the first time it is
729 * called.
730 * This function does additional checks on the hostname to mitigate some
731 * attacks on legacy rhosts-style authentication.
732 * XXX is RhostsRSAAuthentication vulnerable to these?
733 * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?)
734 */
735
736static char *
737remote_hostname(struct ssh *ssh)
738{
739 struct sockaddr_storage from;
740 socklen_t fromlen;
741 struct addrinfo hints, *ai, *aitop;
742 char name[NI_MAXHOST], ntop2[NI_MAXHOST];
743 const char *ntop = ssh_remote_ipaddr(ssh);
744
745 /* Get IP address of client. */
746 fromlen = sizeof(from);
747 memset(&from, 0, sizeof(from));
748 if (getpeername(ssh_packet_get_connection_in(ssh),
deraadt@openbsd.org4d28fa72019-06-28 13:35:04 +0000749 (struct sockaddr *)&from, &fromlen) == -1) {
djm@openbsd.org95767262016-03-07 19:02:43 +0000750 debug("getpeername failed: %.100s", strerror(errno));
751 return strdup(ntop);
752 }
753
754 ipv64_normalise_mapped(&from, &fromlen);
755 if (from.ss_family == AF_INET6)
756 fromlen = sizeof(struct sockaddr_in6);
757
758 debug3("Trying to reverse map address %.100s.", ntop);
759 /* Map the IP address to a host name. */
760 if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
761 NULL, 0, NI_NAMEREQD) != 0) {
762 /* Host name not found. Use ip address. */
763 return strdup(ntop);
764 }
765
766 /*
767 * if reverse lookup result looks like a numeric hostname,
768 * someone is trying to trick us by PTR record like following:
769 * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
770 */
771 memset(&hints, 0, sizeof(hints));
772 hints.ai_socktype = SOCK_DGRAM; /*dummy*/
773 hints.ai_flags = AI_NUMERICHOST;
774 if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
775 logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
776 name, ntop);
777 freeaddrinfo(ai);
778 return strdup(ntop);
779 }
780
781 /* Names are stored in lowercase. */
782 lowercase(name);
783
784 /*
785 * Map it back to an IP address and check that the given
786 * address actually is an address of this host. This is
787 * necessary because anyone with access to a name server can
788 * define arbitrary names for an IP address. Mapping from
789 * name to IP address can be trusted better (but can still be
790 * fooled if the intruder has access to the name server of
791 * the domain).
792 */
793 memset(&hints, 0, sizeof(hints));
794 hints.ai_family = from.ss_family;
795 hints.ai_socktype = SOCK_STREAM;
796 if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
797 logit("reverse mapping checking getaddrinfo for %.700s "
dtucker@openbsd.orge690fe82016-06-15 00:40:40 +0000798 "[%s] failed.", name, ntop);
djm@openbsd.org95767262016-03-07 19:02:43 +0000799 return strdup(ntop);
800 }
801 /* Look for the address from the list of addresses. */
802 for (ai = aitop; ai; ai = ai->ai_next) {
803 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
804 sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
805 (strcmp(ntop, ntop2) == 0))
806 break;
807 }
808 freeaddrinfo(aitop);
809 /* If we reached the end of the list, the address was not there. */
810 if (ai == NULL) {
811 /* Address not found for the host name. */
812 logit("Address %.100s maps to %.600s, but this does not "
dtucker@openbsd.orge690fe82016-06-15 00:40:40 +0000813 "map back to the address.", ntop, name);
djm@openbsd.org95767262016-03-07 19:02:43 +0000814 return strdup(ntop);
815 }
816 return strdup(name);
817}
818
819/*
820 * Return the canonical name of the host in the other side of the current
821 * connection. The host name is cached, so it is efficient to call this
822 * several times.
823 */
824
825const char *
826auth_get_canonical_hostname(struct ssh *ssh, int use_dns)
827{
828 static char *dnsname;
829
830 if (!use_dns)
831 return ssh_remote_ipaddr(ssh);
832 else if (dnsname != NULL)
833 return dnsname;
834 else {
835 dnsname = remote_hostname(ssh);
836 return dnsname;
837 }
838}
markus@openbsd.org25cf9102018-01-08 15:21:49 +0000839
840/*
martijn@openbsd.org5dc4c592018-07-11 08:19:35 +0000841 * Runs command in a subprocess with a minimal environment.
markus@openbsd.org25cf9102018-01-08 15:21:49 +0000842 * Returns pid on success, 0 on failure.
843 * The child stdout and stderr maybe captured, left attached or sent to
844 * /dev/null depending on the contents of flags.
845 * "tag" is prepended to log messages.
846 * NB. "command" is only used for logging; the actual command executed is
847 * av[0].
848 */
849pid_t
850subprocess(const char *tag, struct passwd *pw, const char *command,
851 int ac, char **av, FILE **child, u_int flags)
852{
853 FILE *f = NULL;
854 struct stat st;
855 int fd, devnull, p[2], i;
856 pid_t pid;
857 char *cp, errmsg[512];
858 u_int envsize;
859 char **child_env;
860
861 if (child != NULL)
862 *child = NULL;
863
864 debug3("%s: %s command \"%s\" running as %s (flags 0x%x)", __func__,
865 tag, command, pw->pw_name, flags);
866
867 /* Check consistency */
868 if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 &&
869 (flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0) {
870 error("%s: inconsistent flags", __func__);
871 return 0;
872 }
873 if (((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0) != (child == NULL)) {
874 error("%s: inconsistent flags/output", __func__);
875 return 0;
876 }
877
878 /*
879 * If executing an explicit binary, then verify the it exists
880 * and appears safe-ish to execute
881 */
djm@openbsd.org2a358622018-11-16 03:26:01 +0000882 if (!path_absolute(av[0])) {
markus@openbsd.org25cf9102018-01-08 15:21:49 +0000883 error("%s path is not absolute", tag);
884 return 0;
885 }
886 temporarily_use_uid(pw);
deraadt@openbsd.org4d28fa72019-06-28 13:35:04 +0000887 if (stat(av[0], &st) == -1) {
markus@openbsd.org25cf9102018-01-08 15:21:49 +0000888 error("Could not stat %s \"%s\": %s", tag,
889 av[0], strerror(errno));
890 restore_uid();
891 return 0;
892 }
893 if (safe_path(av[0], &st, NULL, 0, errmsg, sizeof(errmsg)) != 0) {
894 error("Unsafe %s \"%s\": %s", tag, av[0], errmsg);
895 restore_uid();
896 return 0;
897 }
898 /* Prepare to keep the child's stdout if requested */
deraadt@openbsd.org4d28fa72019-06-28 13:35:04 +0000899 if (pipe(p) == -1) {
markus@openbsd.org25cf9102018-01-08 15:21:49 +0000900 error("%s: pipe: %s", tag, strerror(errno));
901 restore_uid();
902 return 0;
903 }
904 restore_uid();
905
906 switch ((pid = fork())) {
907 case -1: /* error */
908 error("%s: fork: %s", tag, strerror(errno));
909 close(p[0]);
910 close(p[1]);
911 return 0;
912 case 0: /* child */
913 /* Prepare a minimal environment for the child. */
914 envsize = 5;
915 child_env = xcalloc(sizeof(*child_env), envsize);
916 child_set_env(&child_env, &envsize, "PATH", _PATH_STDPATH);
917 child_set_env(&child_env, &envsize, "USER", pw->pw_name);
918 child_set_env(&child_env, &envsize, "LOGNAME", pw->pw_name);
919 child_set_env(&child_env, &envsize, "HOME", pw->pw_dir);
920 if ((cp = getenv("LANG")) != NULL)
921 child_set_env(&child_env, &envsize, "LANG", cp);
922
923 for (i = 0; i < NSIG; i++)
924 signal(i, SIG_DFL);
925
926 if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
927 error("%s: open %s: %s", tag, _PATH_DEVNULL,
928 strerror(errno));
929 _exit(1);
930 }
931 if (dup2(devnull, STDIN_FILENO) == -1) {
932 error("%s: dup2: %s", tag, strerror(errno));
933 _exit(1);
934 }
935
936 /* Set up stdout as requested; leave stderr in place for now. */
937 fd = -1;
938 if ((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0)
939 fd = p[1];
940 else if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0)
941 fd = devnull;
942 if (fd != -1 && dup2(fd, STDOUT_FILENO) == -1) {
943 error("%s: dup2: %s", tag, strerror(errno));
944 _exit(1);
945 }
946 closefrom(STDERR_FILENO + 1);
947
948 /* Don't use permanently_set_uid() here to avoid fatal() */
deraadt@openbsd.org4d28fa72019-06-28 13:35:04 +0000949 if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) == -1) {
markus@openbsd.org25cf9102018-01-08 15:21:49 +0000950 error("%s: setresgid %u: %s", tag, (u_int)pw->pw_gid,
951 strerror(errno));
952 _exit(1);
953 }
deraadt@openbsd.org4d28fa72019-06-28 13:35:04 +0000954 if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1) {
markus@openbsd.org25cf9102018-01-08 15:21:49 +0000955 error("%s: setresuid %u: %s", tag, (u_int)pw->pw_uid,
956 strerror(errno));
957 _exit(1);
958 }
959 /* stdin is pointed to /dev/null at this point */
960 if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 &&
961 dup2(STDIN_FILENO, STDERR_FILENO) == -1) {
962 error("%s: dup2: %s", tag, strerror(errno));
963 _exit(1);
964 }
965
966 execve(av[0], av, child_env);
967 error("%s exec \"%s\": %s", tag, command, strerror(errno));
968 _exit(127);
969 default: /* parent */
970 break;
971 }
972
973 close(p[1]);
974 if ((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0)
975 close(p[0]);
976 else if ((f = fdopen(p[0], "r")) == NULL) {
977 error("%s: fdopen: %s", tag, strerror(errno));
978 close(p[0]);
979 /* Don't leave zombie child */
980 kill(pid, SIGTERM);
981 while (waitpid(pid, NULL, 0) == -1 && errno == EINTR)
982 ;
983 return 0;
984 }
985 /* Success */
986 debug3("%s: %s pid %ld", __func__, tag, (long)pid);
987 if (child != NULL)
988 *child = f;
989 return pid;
990}
djm@openbsd.org7c856852018-03-03 03:15:51 +0000991
992/* These functions link key/cert options to the auth framework */
993
994/* Log sshauthopt options locally and (optionally) for remote transmission */
995void
996auth_log_authopts(const char *loc, const struct sshauthopt *opts, int do_remote)
997{
998 int do_env = options.permit_user_env && opts->nenv > 0;
999 int do_permitopen = opts->npermitopen > 0 &&
1000 (options.allow_tcp_forwarding & FORWARD_LOCAL) != 0;
djm@openbsd.org93c06ab2018-06-06 18:23:32 +00001001 int do_permitlisten = opts->npermitlisten > 0 &&
1002 (options.allow_tcp_forwarding & FORWARD_REMOTE) != 0;
djm@openbsd.org7c856852018-03-03 03:15:51 +00001003 size_t i;
djm@openbsd.orgbf0fbf22018-03-12 00:52:01 +00001004 char msg[1024], buf[64];
djm@openbsd.org7c856852018-03-03 03:15:51 +00001005
djm@openbsd.orgbf0fbf22018-03-12 00:52:01 +00001006 snprintf(buf, sizeof(buf), "%d", opts->force_tun_device);
djm@openbsd.org7c856852018-03-03 03:15:51 +00001007 /* Try to keep this alphabetically sorted */
djm@openbsd.org93c06ab2018-06-06 18:23:32 +00001008 snprintf(msg, sizeof(msg), "key options:%s%s%s%s%s%s%s%s%s%s%s%s%s",
djm@openbsd.org7c856852018-03-03 03:15:51 +00001009 opts->permit_agent_forwarding_flag ? " agent-forwarding" : "",
1010 opts->force_command == NULL ? "" : " command",
1011 do_env ? " environment" : "",
djm@openbsd.orgbf0fbf22018-03-12 00:52:01 +00001012 opts->valid_before == 0 ? "" : "expires",
djm@openbsd.org7c856852018-03-03 03:15:51 +00001013 do_permitopen ? " permitopen" : "",
djm@openbsd.org93c06ab2018-06-06 18:23:32 +00001014 do_permitlisten ? " permitlisten" : "",
djm@openbsd.org7c856852018-03-03 03:15:51 +00001015 opts->permit_port_forwarding_flag ? " port-forwarding" : "",
1016 opts->cert_principals == NULL ? "" : " principals",
1017 opts->permit_pty_flag ? " pty" : "",
1018 opts->force_tun_device == -1 ? "" : " tun=",
djm@openbsd.orgbf0fbf22018-03-12 00:52:01 +00001019 opts->force_tun_device == -1 ? "" : buf,
djm@openbsd.org7c856852018-03-03 03:15:51 +00001020 opts->permit_user_rc ? " user-rc" : "",
1021 opts->permit_x11_forwarding_flag ? " x11-forwarding" : "");
1022
1023 debug("%s: %s", loc, msg);
1024 if (do_remote)
1025 auth_debug_add("%s: %s", loc, msg);
1026
1027 if (options.permit_user_env) {
1028 for (i = 0; i < opts->nenv; i++) {
1029 debug("%s: environment: %s", loc, opts->env[i]);
1030 if (do_remote) {
1031 auth_debug_add("%s: environment: %s",
1032 loc, opts->env[i]);
1033 }
1034 }
1035 }
1036
1037 /* Go into a little more details for the local logs. */
djm@openbsd.orgbf0fbf22018-03-12 00:52:01 +00001038 if (opts->valid_before != 0) {
1039 format_absolute_time(opts->valid_before, buf, sizeof(buf));
1040 debug("%s: expires at %s", loc, buf);
1041 }
djm@openbsd.org7c856852018-03-03 03:15:51 +00001042 if (opts->cert_principals != NULL) {
1043 debug("%s: authorized principals: \"%s\"",
1044 loc, opts->cert_principals);
1045 }
1046 if (opts->force_command != NULL)
1047 debug("%s: forced command: \"%s\"", loc, opts->force_command);
djm@openbsd.org93c06ab2018-06-06 18:23:32 +00001048 if (do_permitopen) {
djm@openbsd.org7c856852018-03-03 03:15:51 +00001049 for (i = 0; i < opts->npermitopen; i++) {
1050 debug("%s: permitted open: %s",
1051 loc, opts->permitopen[i]);
1052 }
1053 }
djm@openbsd.org93c06ab2018-06-06 18:23:32 +00001054 if (do_permitlisten) {
1055 for (i = 0; i < opts->npermitlisten; i++) {
1056 debug("%s: permitted listen: %s",
1057 loc, opts->permitlisten[i]);
1058 }
1059 }
djm@openbsd.org7c856852018-03-03 03:15:51 +00001060}
1061
1062/* Activate a new set of key/cert options; merging with what is there. */
1063int
1064auth_activate_options(struct ssh *ssh, struct sshauthopt *opts)
1065{
1066 struct sshauthopt *old = auth_opts;
1067 const char *emsg = NULL;
1068
1069 debug("%s: setting new authentication options", __func__);
1070 if ((auth_opts = sshauthopt_merge(old, opts, &emsg)) == NULL) {
1071 error("Inconsistent authentication options: %s", emsg);
1072 return -1;
1073 }
1074 return 0;
1075}
1076
1077/* Disable forwarding, etc for the session */
1078void
1079auth_restrict_session(struct ssh *ssh)
1080{
1081 struct sshauthopt *restricted;
1082
1083 debug("%s: restricting session", __func__);
1084
1085 /* A blank sshauthopt defaults to permitting nothing */
1086 restricted = sshauthopt_new();
djm@openbsd.orgfbb4b5f2018-05-25 07:11:01 +00001087 restricted->permit_pty_flag = 1;
djm@openbsd.org7c856852018-03-03 03:15:51 +00001088 restricted->restricted = 1;
1089
1090 if (auth_activate_options(ssh, restricted) != 0)
1091 fatal("%s: failed to restrict session", __func__);
1092 sshauthopt_free(restricted);
1093}
1094
1095int
1096auth_authorise_keyopts(struct ssh *ssh, struct passwd *pw,
1097 struct sshauthopt *opts, int allow_cert_authority, const char *loc)
1098{
1099 const char *remote_ip = ssh_remote_ipaddr(ssh);
1100 const char *remote_host = auth_get_canonical_hostname(ssh,
1101 options.use_dns);
djm@openbsd.orgbf0fbf22018-03-12 00:52:01 +00001102 time_t now = time(NULL);
1103 char buf[64];
djm@openbsd.org7c856852018-03-03 03:15:51 +00001104
djm@openbsd.orgbf0fbf22018-03-12 00:52:01 +00001105 /*
1106 * Check keys/principals file expiry time.
1107 * NB. validity interval in certificate is handled elsewhere.
1108 */
1109 if (opts->valid_before && now > 0 &&
1110 opts->valid_before < (uint64_t)now) {
1111 format_absolute_time(opts->valid_before, buf, sizeof(buf));
1112 debug("%s: entry expired at %s", loc, buf);
1113 auth_debug_add("%s: entry expired at %s", loc, buf);
1114 return -1;
1115 }
djm@openbsd.org7c856852018-03-03 03:15:51 +00001116 /* Consistency checks */
1117 if (opts->cert_principals != NULL && !opts->cert_authority) {
1118 debug("%s: principals on non-CA key", loc);
1119 auth_debug_add("%s: principals on non-CA key", loc);
1120 /* deny access */
1121 return -1;
1122 }
1123 /* cert-authority flag isn't valid in authorized_principals files */
1124 if (!allow_cert_authority && opts->cert_authority) {
1125 debug("%s: cert-authority flag invalid here", loc);
1126 auth_debug_add("%s: cert-authority flag invalid here", loc);
1127 /* deny access */
1128 return -1;
1129 }
1130
1131 /* Perform from= checks */
1132 if (opts->required_from_host_keys != NULL) {
1133 switch (match_host_and_ip(remote_host, remote_ip,
1134 opts->required_from_host_keys )) {
1135 case 1:
1136 /* Host name matches. */
1137 break;
1138 case -1:
1139 default:
1140 debug("%s: invalid from criteria", loc);
1141 auth_debug_add("%s: invalid from criteria", loc);
1142 /* FALLTHROUGH */
1143 case 0:
1144 logit("%s: Authentication tried for %.100s with "
1145 "correct key but not from a permitted "
1146 "host (host=%.200s, ip=%.200s, required=%.200s).",
1147 loc, pw->pw_name, remote_host, remote_ip,
1148 opts->required_from_host_keys);
1149 auth_debug_add("%s: Your host '%.200s' is not "
1150 "permitted to use this key for login.",
1151 loc, remote_host);
1152 /* deny access */
1153 return -1;
1154 }
1155 }
1156 /* Check source-address restriction from certificate */
1157 if (opts->required_from_host_cert != NULL) {
1158 switch (addr_match_cidr_list(remote_ip,
1159 opts->required_from_host_cert)) {
1160 case 1:
1161 /* accepted */
1162 break;
1163 case -1:
1164 default:
1165 /* invalid */
1166 error("%s: Certificate source-address invalid",
1167 loc);
1168 /* FALLTHROUGH */
1169 case 0:
1170 logit("%s: Authentication tried for %.100s with valid "
1171 "certificate but not from a permitted source "
1172 "address (%.200s).", loc, pw->pw_name, remote_ip);
1173 auth_debug_add("%s: Your address '%.200s' is not "
1174 "permitted to use this certificate for login.",
1175 loc, remote_ip);
1176 return -1;
1177 }
1178 }
1179 /*
1180 *
1181 * XXX this is spammy. We should report remotely only for keys
1182 * that are successful in actual auth attempts, and not PK_OK
1183 * tests.
1184 */
1185 auth_log_authopts(loc, opts, 1);
1186
1187 return 0;
1188}