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Damien Millerb38eff82000-04-01 11:09:21 +10001/*
Ben Lindstrom92a2e382001-03-05 06:59:27 +00002 * Copyright (c) 2000 Markus Friedl. All rights reserved.
Damien Millere4340be2000-09-16 13:29:08 +11003 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Damien Millerb38eff82000-04-01 11:09:21 +100023 */
24
25#include "includes.h"
Ben Lindstrom83647ce2001-06-25 04:30:16 +000026RCSID("$OpenBSD: auth.c,v 1.24 2001/06/23 00:20:57 markus Exp $");
Damien Millerb38eff82000-04-01 11:09:21 +100027
Damien Millerd2c208a2000-05-17 22:00:02 +100028#ifdef HAVE_LOGIN_H
29#include <login.h>
30#endif
Damien Miller1f335fb2000-06-26 11:31:33 +100031#if defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW)
32#include <shadow.h>
33#endif /* defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) */
Damien Millerb38eff82000-04-01 11:09:21 +100034
Ben Lindstrom68c3ce12001-06-10 17:24:51 +000035#ifdef HAVE_LIBGEN_H
Ben Lindstrombfb3a0e2001-06-05 20:25:05 +000036#include <libgen.h>
Ben Lindstrom68c3ce12001-06-10 17:24:51 +000037#endif
Ben Lindstrombfb3a0e2001-06-05 20:25:05 +000038
Ben Lindstrom226cfa02001-01-22 05:34:40 +000039#include "xmalloc.h"
40#include "match.h"
41#include "groupaccess.h"
42#include "log.h"
43#include "servconf.h"
Damien Millerefb4afe2000-04-12 18:45:05 +100044#include "auth.h"
Ben Lindstromdb65e8f2001-01-19 04:26:52 +000045#include "auth-options.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000046#include "canohost.h"
Ben Lindstrombfb3a0e2001-06-05 20:25:05 +000047#include "buffer.h"
48#include "bufaux.h"
Ben Lindstrom83647ce2001-06-25 04:30:16 +000049#include "uidswap.h"
50#include "tildexpand.h"
Damien Millerefb4afe2000-04-12 18:45:05 +100051
Damien Millerb38eff82000-04-01 11:09:21 +100052/* import */
53extern ServerOptions options;
Damien Millerb38eff82000-04-01 11:09:21 +100054
55/*
Kevin Steves7b61cfa2001-01-14 19:11:00 +000056 * Check if the user is allowed to log in via ssh. If user is listed
57 * in DenyUsers or one of user's groups is listed in DenyGroups, false
58 * will be returned. If AllowUsers isn't empty and user isn't listed
59 * there, or if AllowGroups isn't empty and one of user's groups isn't
60 * listed there, false will be returned.
Damien Millerb38eff82000-04-01 11:09:21 +100061 * If the user's shell is not executable, false will be returned.
Damien Miller4af51302000-04-16 11:18:38 +100062 * Otherwise true is returned.
Damien Millerb38eff82000-04-01 11:09:21 +100063 */
Damien Millereba71ba2000-04-29 23:57:08 +100064int
Damien Millerb38eff82000-04-01 11:09:21 +100065allowed_user(struct passwd * pw)
66{
67 struct stat st;
Damien Millere7cf07c2001-03-20 09:15:57 +110068 char *shell;
Damien Millerb38eff82000-04-01 11:09:21 +100069 int i;
70#ifdef WITH_AIXAUTHENTICATE
71 char *loginmsg;
72#endif /* WITH_AIXAUTHENTICATE */
Kevin Stevesa58e0af2000-10-29 14:38:55 +000073#if !defined(USE_PAM) && defined(HAVE_SHADOW_H) && \
Damien Miller62dd94b2000-09-23 14:26:32 +110074 !defined(DISABLE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
Kevin Steves7b61cfa2001-01-14 19:11:00 +000075 struct spwd *spw;
Damien Millerb38eff82000-04-01 11:09:21 +100076
77 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
Kevin Steves7b61cfa2001-01-14 19:11:00 +000078 if (!pw || !pw->pw_name)
Damien Millerb38eff82000-04-01 11:09:21 +100079 return 0;
80
Damien Miller1f335fb2000-06-26 11:31:33 +100081 spw = getspnam(pw->pw_name);
Damien Millerc7088432000-07-02 18:44:54 +100082 if (spw != NULL) {
83 int days = time(NULL) / 86400;
Damien Miller1f335fb2000-06-26 11:31:33 +100084
Damien Millerc7088432000-07-02 18:44:54 +100085 /* Check account expiry */
Damien Miller62dd94b2000-09-23 14:26:32 +110086 if ((spw->sp_expire >= 0) && (days > spw->sp_expire))
Damien Millerc7088432000-07-02 18:44:54 +100087 return 0;
88
89 /* Check password expiry */
Kevin Stevesef4eea92001-02-05 12:42:17 +000090 if ((spw->sp_lstchg >= 0) && (spw->sp_max >= 0) &&
Damien Miller606f8802000-09-16 15:39:56 +110091 (days > (spw->sp_lstchg + spw->sp_max)))
Damien Millerc7088432000-07-02 18:44:54 +100092 return 0;
93 }
Damien Miller1f335fb2000-06-26 11:31:33 +100094#else
95 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
Kevin Steves7b61cfa2001-01-14 19:11:00 +000096 if (!pw || !pw->pw_name)
Damien Miller1f335fb2000-06-26 11:31:33 +100097 return 0;
98#endif
99
Damien Milleref7df542000-05-19 00:03:23 +1000100 /*
101 * Get the shell from the password data. An empty shell field is
102 * legal, and means /bin/sh.
103 */
104 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
105
106 /* deny if shell does not exists or is not executable */
107 if (stat(shell, &st) != 0)
Damien Millerb38eff82000-04-01 11:09:21 +1000108 return 0;
109 if (!((st.st_mode & S_IFREG) && (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP))))
110 return 0;
111
112 /* Return false if user is listed in DenyUsers */
113 if (options.num_deny_users > 0) {
Damien Millerb38eff82000-04-01 11:09:21 +1000114 for (i = 0; i < options.num_deny_users; i++)
115 if (match_pattern(pw->pw_name, options.deny_users[i]))
116 return 0;
117 }
118 /* Return false if AllowUsers isn't empty and user isn't listed there */
119 if (options.num_allow_users > 0) {
Damien Millerb38eff82000-04-01 11:09:21 +1000120 for (i = 0; i < options.num_allow_users; i++)
121 if (match_pattern(pw->pw_name, options.allow_users[i]))
122 break;
123 /* i < options.num_allow_users iff we break for loop */
124 if (i >= options.num_allow_users)
125 return 0;
126 }
Damien Millerb38eff82000-04-01 11:09:21 +1000127 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
Kevin Steves7b61cfa2001-01-14 19:11:00 +0000128 /* Get the user's group access list (primary and supplementary) */
129 if (ga_init(pw->pw_name, pw->pw_gid) == 0)
Damien Millerb38eff82000-04-01 11:09:21 +1000130 return 0;
131
Kevin Steves7b61cfa2001-01-14 19:11:00 +0000132 /* Return false if one of user's groups is listed in DenyGroups */
133 if (options.num_deny_groups > 0)
134 if (ga_match(options.deny_groups,
135 options.num_deny_groups)) {
136 ga_free();
Damien Millerb38eff82000-04-01 11:09:21 +1000137 return 0;
Kevin Steves7b61cfa2001-01-14 19:11:00 +0000138 }
Damien Millerb38eff82000-04-01 11:09:21 +1000139 /*
Kevin Steves7b61cfa2001-01-14 19:11:00 +0000140 * Return false if AllowGroups isn't empty and one of user's groups
Damien Millerb38eff82000-04-01 11:09:21 +1000141 * isn't listed there
142 */
Kevin Steves7b61cfa2001-01-14 19:11:00 +0000143 if (options.num_allow_groups > 0)
144 if (!ga_match(options.allow_groups,
145 options.num_allow_groups)) {
146 ga_free();
Damien Millerb38eff82000-04-01 11:09:21 +1000147 return 0;
Kevin Steves7b61cfa2001-01-14 19:11:00 +0000148 }
149 ga_free();
Damien Millerb38eff82000-04-01 11:09:21 +1000150 }
151
152#ifdef WITH_AIXAUTHENTICATE
Damien Miller2f6a0ad2000-05-31 11:20:11 +1000153 if (loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &loginmsg) != 0) {
Damien Millerd2c208a2000-05-17 22:00:02 +1000154 if (loginmsg && *loginmsg) {
155 /* Remove embedded newlines (if any) */
156 char *p;
Damien Miller2f6a0ad2000-05-31 11:20:11 +1000157 for (p = loginmsg; *p; p++) {
Damien Millerd2c208a2000-05-17 22:00:02 +1000158 if (*p == '\n')
159 *p = ' ';
Damien Miller2f6a0ad2000-05-31 11:20:11 +1000160 }
Damien Millerd2c208a2000-05-17 22:00:02 +1000161 /* Remove trailing newline */
162 *--p = '\0';
Damien Miller2f6a0ad2000-05-31 11:20:11 +1000163 log("Login restricted for %s: %.100s", pw->pw_name, loginmsg);
Damien Millerd2c208a2000-05-17 22:00:02 +1000164 }
Damien Millerb38eff82000-04-01 11:09:21 +1000165 return 0;
Damien Millerd2c208a2000-05-17 22:00:02 +1000166 }
Damien Millerb38eff82000-04-01 11:09:21 +1000167#endif /* WITH_AIXAUTHENTICATE */
168
169 /* We found no reason not to let this user try to log on... */
170 return 1;
171}
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000172
173Authctxt *
174authctxt_new(void)
175{
Kevin Stevesef4eea92001-02-05 12:42:17 +0000176 Authctxt *authctxt = xmalloc(sizeof(*authctxt));
177 memset(authctxt, 0, sizeof(*authctxt));
178 return authctxt;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000179}
180
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000181void
182auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
183{
184 void (*authlog) (const char *fmt,...) = verbose;
185 char *authmsg;
186
187 /* Raise logging level */
188 if (authenticated == 1 ||
189 !authctxt->valid ||
190 authctxt->failures >= AUTH_FAIL_LOG ||
191 strcmp(method, "password") == 0)
192 authlog = log;
193
194 if (authctxt->postponed)
195 authmsg = "Postponed";
196 else
197 authmsg = authenticated ? "Accepted" : "Failed";
198
199 authlog("%s %s for %s%.100s from %.200s port %d%s",
200 authmsg,
201 method,
202 authctxt->valid ? "" : "illegal user ",
203 authctxt->valid && authctxt->pw->pw_uid == 0 ? "ROOT" : authctxt->user,
204 get_remote_ipaddr(),
205 get_remote_port(),
206 info);
207}
208
209/*
Ben Lindstromd8a90212001-02-15 03:08:27 +0000210 * Check whether root logins are disallowed.
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000211 */
212int
Ben Lindstromd8a90212001-02-15 03:08:27 +0000213auth_root_allowed(char *method)
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000214{
Ben Lindstromd8a90212001-02-15 03:08:27 +0000215 switch (options.permit_root_login) {
216 case PERMIT_YES:
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000217 return 1;
Ben Lindstromd8a90212001-02-15 03:08:27 +0000218 break;
219 case PERMIT_NO_PASSWD:
220 if (strcmp(method, "password") != 0)
221 return 1;
222 break;
223 case PERMIT_FORCED_ONLY:
224 if (forced_command) {
225 log("Root login accepted for forced command.");
226 return 1;
227 }
228 break;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000229 }
Ben Lindstromd8a90212001-02-15 03:08:27 +0000230 log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
231 return 0;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000232}
Ben Lindstrombfb3a0e2001-06-05 20:25:05 +0000233
234
235/*
236 * Given a template and a passwd structure, build a filename
237 * by substituting % tokenised options. Currently, %% becomes '%',
238 * %h becomes the home directory and %u the username.
239 *
240 * This returns a buffer allocated by xmalloc.
241 */
242char *
243expand_filename(const char *filename, struct passwd *pw)
244{
245 Buffer buffer;
246 char *file;
247 const char *cp;
248
249 /*
250 * Build the filename string in the buffer by making the appropriate
251 * substitutions to the given file name.
252 */
253 buffer_init(&buffer);
254 for (cp = filename; *cp; cp++) {
255 if (cp[0] == '%' && cp[1] == '%') {
256 buffer_append(&buffer, "%", 1);
257 cp++;
258 continue;
259 }
260 if (cp[0] == '%' && cp[1] == 'h') {
261 buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
262 cp++;
263 continue;
264 }
265 if (cp[0] == '%' && cp[1] == 'u') {
266 buffer_append(&buffer, pw->pw_name,
267 strlen(pw->pw_name));
268 cp++;
269 continue;
270 }
271 buffer_append(&buffer, cp, 1);
272 }
273 buffer_append(&buffer, "\0", 1);
274
275 /*
276 * Ensure that filename starts anchored. If not, be backward
277 * compatible and prepend the '%h/'
278 */
279 file = xmalloc(MAXPATHLEN);
280 cp = buffer_ptr(&buffer);
281 if (*cp != '/')
282 snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
283 else
284 strlcpy(file, cp, MAXPATHLEN);
285
286 buffer_free(&buffer);
287 return file;
288}
289
290char *
291authorized_keys_file(struct passwd *pw)
292{
293 return expand_filename(options.authorized_keys_file, pw);
294}
295
296char *
297authorized_keys_file2(struct passwd *pw)
298{
299 return expand_filename(options.authorized_keys_file2, pw);
300}
301
Ben Lindstrom83647ce2001-06-25 04:30:16 +0000302/* return ok if key exists in sysfile or userfile */
303HostStatus
304check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
305 const char *sysfile, const char *userfile)
306{
307 Key *found;
308 char *user_hostfile;
309 struct stat st;
310 int host_status;
311
312 /* Check if we know the host and its host key. */
313 found = key_new(key->type);
314 host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
315
316 if (host_status != HOST_OK && userfile != NULL) {
317 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
318 if (options.strict_modes &&
319 (stat(user_hostfile, &st) == 0) &&
320 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
321 (st.st_mode & 022) != 0)) {
322 log("Authentication refused for %.100s: "
323 "bad owner or modes for %.200s",
324 pw->pw_name, user_hostfile);
325 } else {
326 temporarily_use_uid(pw);
327 host_status = check_host_in_hostfile(user_hostfile,
328 host, key, found, NULL);
329 restore_uid();
330 }
331 xfree(user_hostfile);
332 }
333 key_free(found);
334
335 debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
336 "ok" : "not found", host);
337 return host_status;
338}
339
340
Ben Lindstrombfb3a0e2001-06-05 20:25:05 +0000341/*
342 * Check a given file for security. This is defined as all components
343 * of the path to the file must either be owned by either the owner of
Ben Lindstrom60567ff2001-06-05 20:27:53 +0000344 * of the file or root and no directories must be group or world writable.
Ben Lindstrombfb3a0e2001-06-05 20:25:05 +0000345 *
346 * XXX Should any specific check be done for sym links ?
347 *
348 * Takes an open file descriptor, the file name, a uid and and
349 * error buffer plus max size as arguments.
350 *
351 * Returns 0 on success and -1 on failure
352 */
353int
354secure_filename(FILE *f, const char *file, uid_t uid, char *err, size_t errlen)
355{
356 char buf[MAXPATHLEN];
357 char *cp;
358 struct stat st;
359
360 if (realpath(file, buf) == NULL) {
361 snprintf(err, errlen, "realpath %s failed: %s", file,
362 strerror(errno));
363 return -1;
364 }
365
366 /* check the open file to avoid races */
367 if (fstat(fileno(f), &st) < 0 ||
368 (st.st_uid != 0 && st.st_uid != uid) ||
369 (st.st_mode & 022) != 0) {
370 snprintf(err, errlen, "bad ownership or modes for file %s",
371 buf);
372 return -1;
373 }
374
375 /* for each component of the canonical path, walking upwards */
376 for (;;) {
377 if ((cp = dirname(buf)) == NULL) {
378 snprintf(err, errlen, "dirname() failed");
379 return -1;
380 }
381 strlcpy(buf, cp, sizeof(buf));
382
383 debug3("secure_filename: checking '%s'", buf);
384 if (stat(buf, &st) < 0 ||
385 (st.st_uid != 0 && st.st_uid != uid) ||
386 (st.st_mode & 022) != 0) {
387 snprintf(err, errlen,
388 "bad ownership or modes for directory %s", buf);
389 return -1;
390 }
391
392 /*
393 * dirname should always complete with a "/" path,
394 * but we can be paranoid and check for "." too
395 */
396 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
397 break;
398 }
399 return 0;
400}