1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 #pragma ident	"%Z%%M%	%I%	%E% SMI"
27 
28 
29 #include <kadm5/admin.h>
30 #include <krb5.h>
31 
32 #include <security/pam_appl.h>
33 #include <security/pam_modules.h>
34 #include <security/pam_impl.h>
35 #include <syslog.h>
36 #include <string.h>
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <sys/types.h>
40 #include <pwd.h>
41 #include <libintl.h>
42 #include <netdb.h>
43 #include "utils.h"
44 #include <shadow.h>
45 
46 #include "krb5_repository.h"
47 
48 #define	KRB5_AUTOMIGRATE_DATA	"SUNW-KRB5-AUTOMIGRATE-DATA"
49 
50 #define	min(a, b) ((a) < (b) ? (a) : (b))
51 
52 /*
53  * pam_sm_acct_mgmt	  main account managment routine.
54  */
55 
56 static int
57 fetch_princ_entry(
58 	krb5_module_data_t *kmd,
59 	char *princ_str,
60 	kadm5_principal_ent_rec *prent,	/* out */
61 	int debug)
62 
63 {
64 	kadm5_ret_t		code;
65 	krb5_principal 		princ = 0;
66 	char 			admin_realm[1024];
67 	char			kprinc[2*MAXHOSTNAMELEN];
68 	char			*cpw_service, *password;
69 	void 			*server_handle;
70 	krb5_context		context;
71 	kadm5_config_params	params;
72 
73 	password = kmd->password;
74 	context = kmd->kcontext;
75 
76 	if ((code = get_kmd_kuser(context, (const char *)princ_str,
77 	    kprinc, 2*MAXHOSTNAMELEN)) != 0) {
78 		return (code);
79 	}
80 
81 	code = krb5_parse_name(context, kprinc, &princ);
82 	if (code != 0) {
83 		return (PAM_SYSTEM_ERR);
84 	}
85 
86 	if (strlen(password) == 0) {
87 		krb5_free_principal(context, princ);
88 		if (debug)
89 			__pam_log(LOG_AUTH | LOG_DEBUG,
90 			    "PAM-KRB5 (acct): fetch_princ_entry: pwlen=0");
91 		return (PAM_AUTH_ERR);
92 	}
93 
94 	(void) strlcpy(admin_realm,
95 		    krb5_princ_realm(context, princ)->data,
96 		    sizeof (admin_realm));
97 
98 	(void) memset((char *)&params, 0, sizeof (params));
99 	params.mask |= KADM5_CONFIG_REALM;
100 	params.realm = admin_realm;
101 
102 	if (kadm5_get_cpw_host_srv_name(context, admin_realm, &cpw_service)) {
103 		__pam_log(LOG_AUTH | LOG_ERR,
104 			"PAM-KRB5 (acct):  unable to get host based "
105 			"service name for realm '%s'",
106 			admin_realm);
107 		krb5_free_principal(context, princ);
108 		return (PAM_SYSTEM_ERR);
109 	}
110 
111 	code = kadm5_init_with_password(kprinc, password, cpw_service,
112 					&params, KADM5_STRUCT_VERSION,
113 					KADM5_API_VERSION_2, &server_handle);
114 	if (code != 0) {
115 		if (debug)
116 			__pam_log(LOG_AUTH | LOG_DEBUG,
117 			    "PAM-KRB5 (acct): fetch_princ_entry: "
118 			    "init_with_pw failed: code = %d", code);
119 		krb5_free_principal(context, princ);
120 		return ((code == KADM5_BAD_PASSWORD) ?
121 			PAM_AUTH_ERR : PAM_SYSTEM_ERR);
122 	}
123 
124 	if (_kadm5_get_kpasswd_protocol(server_handle) != KRB5_CHGPWD_RPCSEC) {
125 		if (debug)
126 			__pam_log(LOG_AUTH | LOG_DEBUG,
127 			    "PAM-KRB5 (acct): fetch_princ_entry: "
128 			    "non-RPCSEC_GSS chpw server, can't get "
129 			    "princ entry");
130 		(void) kadm5_destroy(server_handle);
131 		krb5_free_principal(context, princ);
132 		return (PAM_SYSTEM_ERR);
133 	}
134 
135 	code = kadm5_get_principal(server_handle, princ, prent,
136 				KADM5_PRINCIPAL_NORMAL_MASK);
137 
138 	if (code != 0) {
139 		(void) kadm5_destroy(server_handle);
140 		krb5_free_principal(context, princ);
141 		return ((code == KADM5_UNK_PRINC) ?
142 			PAM_USER_UNKNOWN : PAM_SYSTEM_ERR);
143 	}
144 
145 	(void) kadm5_destroy(server_handle);
146 	krb5_free_principal(context, princ);
147 
148 	return (PAM_SUCCESS);
149 }
150 
151 /*
152  * exp_warn
153  *
154  * Warn the user if their pw is set to expire.
155  *
156  * We first check to see if the KDC had set any account or password
157  * expiration information in the key expiration field.  If this was
158  * not set then we must assume that the KDC could be broken and revert
159  * to fetching pw/account expiration information from kadm.  We can not
160  * determine the difference between broken KDCs that do not send key-exp
161  * vs. principals that do not have an expiration policy.  The up-shot
162  * is that pam_krb5 will probably not be stacked for acct mgmt if the
163  * environment does not have an exp policy, avoiding the second exchange
164  * using the kadm protocol.
165  */
166 static int
167 exp_warn(
168 	pam_handle_t *pamh,
169 	char *user,
170 	krb5_module_data_t *kmd,
171 	int debug)
172 
173 {
174 	int err;
175 	kadm5_principal_ent_rec prent;
176 	krb5_timestamp  now, days, expiration;
177 	char    messages[PAM_MAX_NUM_MSG][PAM_MAX_MSG_SIZE], *password;
178 	krb5_error_code code;
179 
180 	if (debug)
181 		__pam_log(LOG_AUTH | LOG_DEBUG,
182 		    "PAM-KRB5 (acct): exp_warn start: user = '%s'",
183 		    user ? user : "<null>");
184 
185 	password = kmd->password;
186 
187 	if (!pamh || !user || !password) {
188 		err = PAM_SERVICE_ERR;
189 		goto exit;
190 	}
191 
192 	/*
193 	 * If we error out from krb5_init_context, then just set error code,
194 	 * check to see about debug message and exit out of routine as the
195 	 * context could not possibly have been setup.
196 	 */
197 
198 	if (code = krb5_init_context(&kmd->kcontext)) {
199 		err = PAM_SYSTEM_ERR;
200 		if (debug)
201 			__pam_log(LOG_AUTH | LOG_ERR, "PAM-KRB5 (acct): "
202 			    "krb5_init_context failed: code=%d",
203 			    code);
204 		goto exit;
205 	}
206 	if (code = krb5_timeofday(kmd->kcontext, &now)) {
207 		err = PAM_SYSTEM_ERR;
208 		if (debug)
209 			__pam_log(LOG_AUTH | LOG_ERR,
210 			    "PAM-KRB5 (acct): krb5_timeofday failed: code=%d",
211 			    code);
212 		goto out;
213 	}
214 
215 	if (kmd->expiration != 0) {
216 		expiration = kmd->expiration;
217 	} else {
218 		(void) memset(&prent, 0, sizeof (prent));
219 		if ((err = fetch_princ_entry(kmd, user, &prent, debug))
220 		    != PAM_SUCCESS) {
221 			if (debug)
222 				__pam_log(LOG_AUTH | LOG_DEBUG,
223 				"PAM-KRB5 (acct): exp_warn: fetch_pr failed %d",
224 				err);
225 			goto out;
226 		}
227 		if (prent.princ_expire_time != 0 && prent.pw_expiration != 0)
228 			expiration = min(prent.princ_expire_time,
229 				prent.pw_expiration);
230 		else
231 			expiration = prent.princ_expire_time ?
232 				prent.princ_expire_time : prent.pw_expiration;
233 	}
234 
235 	if (debug)
236 		__pam_log(LOG_AUTH | LOG_DEBUG,
237 		    "PAM-KRB5 (acct): exp_warn: "
238 		    "princ/pw_exp exp=%ld, now =%ld, days=%ld",
239 		    expiration,
240 		    now,
241 		    expiration > 0
242 		    ? ((expiration - now) / DAY)
243 		    : 0);
244 
245 	/* warn user if principal's pw is set to expire */
246 	if (expiration > 0) {
247 		days = (expiration - now) / DAY;
248 		if (days <= 0)
249 			(void) snprintf(messages[0],
250 				sizeof (messages[0]),
251 				dgettext(TEXT_DOMAIN,
252 				"Your Kerberos account/password will expire "
253 				"within 24 hours.\n"));
254 		else if (days == 1)
255 			(void) snprintf(messages[0],
256 				sizeof (messages[0]),
257 				dgettext(TEXT_DOMAIN,
258 				"Your Kerberos account/password will expire "
259 				"in 1 day.\n"));
260 		else
261 			(void) snprintf(messages[0],
262 				sizeof (messages[0]),
263 				dgettext(TEXT_DOMAIN,
264 				"Your Kerberos account/password will expire in "
265 				"%d days.\n"),
266 				(int)days);
267 
268 		(void) __pam_display_msg(pamh, PAM_TEXT_INFO, 1,
269 					messages, NULL);
270 	}
271 
272 	/* things went smooth */
273 	err = PAM_SUCCESS;
274 
275 out:
276 
277 	if (kmd->kcontext) {
278 		krb5_free_context(kmd->kcontext);
279 		kmd->kcontext = NULL;
280 	}
281 
282 exit:
283 
284 	if (debug)
285 		__pam_log(LOG_AUTH | LOG_DEBUG,
286 		    "PAM-KRB5 (acct): exp_warn end: err = %d", err);
287 
288 	return (err);
289 }
290 
291 /*
292  * pam_krb5 acct_mgmt
293  *
294  * we do
295  *    - check if pw expired (flag set in auth)
296  *    - warn user if pw is set to expire
297  *
298  * notes
299  *    - we require the auth module to have already run (sets module data)
300  *    - we don't worry about an expired princ cuz if that's the case,
301  *      auth would have failed
302  */
303 int
304 pam_sm_acct_mgmt(
305 	pam_handle_t *pamh,
306 	int	flags,
307 	int	argc,
308 	const char **argv)
309 
310 {
311 	char *user = NULL;
312 	char *userdata = NULL;
313 	int err;
314 	int i;
315 	krb5_module_data_t *kmd = NULL;
316 	char    messages[PAM_MAX_NUM_MSG][PAM_MAX_MSG_SIZE];
317 	int debug = 0;  /* pam.conf entry option */
318 	int nowarn = 0; /* pam.conf entry option, no expire warnings */
319 	pam_repository_t	*rep_data = NULL;
320 
321 	for (i = 0; i < argc; i++) {
322 		if (strcasecmp(argv[i], "debug") == 0)
323 			debug = 1;
324 		else if (strcasecmp(argv[i], "nowarn") == 0) {
325 			nowarn = 1;
326 			flags = flags | PAM_SILENT;
327 		} else {
328 			__pam_log(LOG_AUTH | LOG_ERR,
329 			    "PAM-KRB5 (acct): illegal option %s",
330 			    argv[i]);
331 		}
332 	}
333 
334 	if (debug)
335 		__pam_log(LOG_AUTH | LOG_DEBUG,
336 		    "PAM-KRB5 (acct): debug=%d, nowarn=%d",
337 		    debug, nowarn);
338 
339 	(void) pam_get_item(pamh, PAM_REPOSITORY, (void **)&rep_data);
340 
341 	if (rep_data != NULL) {
342 		/*
343 		 * If the repository is not ours,
344 		 * return PAM_IGNORE.
345 		 */
346 		if (strcmp(rep_data->type, KRB5_REPOSITORY_NAME) != 0) {
347 			if (debug)
348 				__pam_log(LOG_AUTH | LOG_DEBUG,
349 					"PAM-KRB5 (acct): wrong"
350 					"repository found (%s), returning "
351 					"PAM_IGNORE", rep_data->type);
352 			return (PAM_IGNORE);
353 		}
354 	}
355 
356 
357 	/* get user name */
358 	(void) pam_get_item(pamh, PAM_USER, (void **) &user);
359 
360 	if (user == NULL || *user == '\0') {
361 		err = PAM_USER_UNKNOWN;
362 		goto out;
363 	}
364 
365 	/* get pam_krb5_migrate specific data */
366 	err = pam_get_data(pamh, KRB5_AUTOMIGRATE_DATA,
367 					(const void **)&userdata);
368 	if (err != PAM_SUCCESS) {
369 		if (debug)
370 			__pam_log(LOG_AUTH | LOG_DEBUG, "PAM-KRB5 (acct): "
371 				"no module data for KRB5_AUTOMIGRATE_DATA");
372 	} else {
373 		/*
374 		 * We try and reauthenticate, since this user has a
375 		 * newly created krb5 principal via the pam_krb5_migrate
376 		 * auth module. That way, this new user will have fresh
377 		 * creds (assuming pam_sm_authenticate() succeeds).
378 		 */
379 		if (strcmp(user, userdata) == 0)
380 			(void) pam_sm_authenticate(pamh, flags, argc,
381 					(const char **)argv);
382 		else
383 			if (debug)
384 				__pam_log(LOG_AUTH | LOG_DEBUG,
385 				"PAM-KRB5 (acct): PAM_USER %s"
386 				"does not match user %s from pam_get_data()",
387 				user, (char *)userdata);
388 	}
389 
390 	/* get krb5 module data  */
391 	if ((err = pam_get_data(pamh, KRB5_DATA, (const void **)&kmd))
392 	    != PAM_SUCCESS) {
393 		if (err == PAM_NO_MODULE_DATA) {
394 			/*
395 			 * pam_auth never called (possible config
396 			 * error; no pam_krb5 auth entry in pam.conf),
397 			 */
398 			if (debug) {
399 				__pam_log(LOG_AUTH | LOG_DEBUG,
400 				    "PAM-KRB5 (acct): no module data");
401 			}
402 			err = PAM_IGNORE;
403 			goto out;
404 		} else {
405 			__pam_log(LOG_AUTH | LOG_ERR,
406 				    "PAM-KRB5 (acct): get module"
407 				    " data failed: err=%d",
408 			    err);
409 		}
410 		goto out;
411 	}
412 
413 	debug = debug || kmd->debug;
414 
415 	/*
416 	 * auth mod set status to ignore, most likely cuz root key is
417 	 * in keytab, so skip other checks and return ignore
418 	 */
419 	if (kmd->auth_status == PAM_IGNORE) {
420 		if (debug)
421 			__pam_log(LOG_AUTH | LOG_DEBUG,
422 			    "PAM-KRB5 (acct): kmd auth_status is IGNORE");
423 		err = PAM_IGNORE;
424 		goto out;
425 	}
426 
427 	/*
428 	 * If there is no Kerberos related user and there is authentication
429 	 * data, this means that while the user has successfully passed
430 	 * authentication, Kerberos is not the account authority because there
431 	 * is no valid Kerberos principal.  PAM_IGNORE is returned since
432 	 * Kerberos is not authoritative for this user.  Other modules in the
433 	 * account stack will need to determine the success or failure for this
434 	 * user.
435 	 */
436 	if (kmd->auth_status == PAM_USER_UNKNOWN) {
437 		if (debug)
438 			syslog(LOG_DEBUG,
439 			    "PAM-KRB5 (acct): kmd auth_status is USER UNKNOWN");
440 		err = PAM_IGNORE;
441 		goto out;
442 	}
443 
444 	/*
445 	 * age_status will be set to PAM_NEW_AUTHTOK_REQD in pam_krb5's
446 	 * 'auth' if the user's key/pw has expired and needs to be changed
447 	 */
448 	if (kmd->age_status == PAM_NEW_AUTHTOK_REQD) {
449 		if (!nowarn) {
450 			(void) snprintf(messages[0], sizeof (messages[0]),
451 				dgettext(TEXT_DOMAIN,
452 				"Your Kerberos password has expired.\n"));
453 			(void) __pam_display_msg(pamh, PAM_TEXT_INFO,
454 					1, messages, NULL);
455 		}
456 		err = PAM_NEW_AUTHTOK_REQD;
457 		goto out;
458 	}
459 
460 	if (kmd->auth_status == PAM_SUCCESS && !(flags & PAM_SILENT) &&
461 	    !nowarn && kmd->password) {
462 		/* if we fail, let it slide, it's only a warning brah */
463 		(void) exp_warn(pamh, user, kmd, debug);
464 	}
465 
466 	/*
467 	 * If Kerberos is treated as optional in the PAM stack, it is possible
468 	 * that there is a KRB5_DATA item and a non-Kerberos account authority.
469 	 * In that case, PAM_IGNORE is returned.
470 	 */
471 	err = kmd->auth_status != PAM_SUCCESS ? PAM_IGNORE : kmd->auth_status;
472 
473 out:
474 	if (debug)
475 		__pam_log(LOG_AUTH | LOG_DEBUG,
476 		    "PAM-KRB5 (acct): end: %s", pam_strerror(pamh, err));
477 
478 	return (err);
479 }
480