xref: /illumos-gate/usr/src/lib/pam_modules/unix_auth/unix_auth.c (revision c6df5f150cc6712f476458ae066069ec2d3dc264)
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 2009 Sun Microsystems, Inc.  All rights reserved.
23   * Use is subject to license terms.
24   *
25   * Copyright 2023 OmniOS Community Edition (OmniOSce) Association.
26   */
27  
28  
29  #include <stdlib.h>
30  #include <pwd.h>
31  #include <shadow.h>
32  #include <syslog.h>
33  #include <errno.h>
34  #include <string.h>
35  #include <crypt.h>
36  #include <unistd.h>
37  #include <user_attr.h>
38  #include <auth_attr.h>
39  #include <userdefs.h>
40  #include <deflt.h>
41  #include <sys/stat.h>
42  #include <sys/param.h>
43  #include <stdarg.h>
44  
45  #include <security/pam_appl.h>
46  #include <security/pam_modules.h>
47  #include <security/pam_impl.h>
48  
49  #include <libintl.h>
50  
51  #include <passwdutil.h>
52  
53  #define	LOGINADMIN	"/etc/default/login"
54  #define	MAXTRYS		5
55  
56  /*PRINTFLIKE2*/
57  void
58  error(pam_handle_t *pamh, char *fmt, ...)
59  {
60  	va_list ap;
61  	char messages[1][PAM_MAX_MSG_SIZE];
62  
63  	va_start(ap, fmt);
64  	(void) vsnprintf(messages[0], sizeof (messages[0]), fmt, ap);
65  	(void) __pam_display_msg(pamh, PAM_ERROR_MSG, 1, messages, NULL);
66  	va_end(ap);
67  }
68  
69  static int
70  get_max_failed(const char *user)
71  {
72  	char *val = NULL;
73  	userattr_t *uattr;
74  	int do_lock = 0;
75  	int retval = 0;
76  	char *p;
77  	void	*defp;
78  
79  	if ((uattr = getusernam(user)) != NULL)
80  		val = kva_match(uattr->attr, USERATTR_LOCK_AFTER_RETRIES_KW);
81  
82  	if (val != NULL) {
83  		do_lock = (strcasecmp(val, "yes") == 0);
84  	} else if ((defp = defopen_r(AUTH_POLICY)) != NULL) {
85  		int flags;
86  		flags = defcntl_r(DC_GETFLAGS, 0, defp);
87  		TURNOFF(flags, DC_CASE);
88  		(void) defcntl_r(DC_SETFLAGS, flags, defp);
89  		if ((p = defread_r("LOCK_AFTER_RETRIES=", defp)) != NULL)
90  			do_lock = (strcasecmp(p, "yes") == 0);
91  		defclose_r(defp);
92  	}
93  
94  	if (uattr != NULL)
95  		free_userattr(uattr);
96  
97  	if (do_lock) {
98  		retval = MAXTRYS;
99  		if ((defp = defopen_r(LOGINADMIN)) != NULL) {
100  			if ((p = defread_r("RETRIES=", defp)) != NULL)
101  				retval = atoi(p);
102  			defclose_r(defp);
103  		}
104  	}
105  
106  	return (retval);
107  }
108  
109  static void
110  display_warning(pam_handle_t *pamh, int failures, char *homedir)
111  {
112  	char hushpath[MAXPATHLEN];
113  	struct stat buf;
114  
115  	(void) snprintf(hushpath, sizeof (hushpath), "%s/.hushlogin", homedir);
116  	if (stat(hushpath, &buf) == 0)
117  		return;
118  
119  	if (failures == 1)
120  		error(pamh, "Warning: 1 failed login attempt since last "
121  		    "successful login.");
122  	else if (failures < FAILCOUNT_MASK)
123  		error(pamh, "Warning: %d failed login attempts since last "
124  		    "successful login.", failures);
125  	else
126  		error(pamh, "Warning: at least %d failed login attempts since "
127  		    "last successful login.", failures);
128  }
129  
130  /*
131   * int pam_sm_authenticate(pamh, flags, arc, argv)
132   *
133   * This routine verifies that the password as stored in the
134   * PAM_AUTHTOK item is indeed the password that belongs to the user
135   * as stored in PAM_USER.
136   *
137   * This routine will not establish Secure RPC Credentials, the pam_dhkeys
138   * module should be stacked before us if Secure RPC Credentials are needed
139   * to obtain passwords.
140   */
141  int
142  pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, const char **argv)
143  {
144  	int i;
145  	int debug = 0;
146  	int nowarn = (flags & PAM_SILENT) != 0;
147  	const char *user;
148  	const char *passwd;
149  	char *rep_passwd;
150  	char *crypt_passwd;
151  	char *repository_name;
152  	const struct pam_repository *auth_rep;
153  	pwu_repository_t *pwu_rep;
154  	attrlist attr_pw[4];
155  	int result;
156  	int server_policy = 0;
157  	int old_failed_count;
158  	char *homedir = NULL;
159  	int dolock = 1;
160  
161  	for (i = 0; i < argc; i++) {
162  		if (strcmp(argv[i], "debug") == 0)
163  			debug = 1;
164  		else if (strcmp(argv[i], "nowarn") == 0)
165  			nowarn = 1;
166  		else if (strcmp(argv[i], "server_policy") == 0)
167  			server_policy = 1;
168  		else if (strcmp(argv[i], "nolock") == 0)
169  			dolock = 0;
170  	}
171  
172  	if (debug)
173  		__pam_log(LOG_AUTH | LOG_DEBUG,
174  		    "pam_unix_auth: entering pam_sm_authenticate()");
175  
176  	if (pam_get_item(pamh, PAM_USER, (const void **)&user) != PAM_SUCCESS) {
177  		__pam_log(LOG_AUTH | LOG_DEBUG, "pam_unix_auth: USER not set");
178  		return (PAM_SYSTEM_ERR);
179  	}
180  
181  	if (user == NULL || *user == '\0') {
182  		__pam_log(LOG_AUTH | LOG_DEBUG,
183  		    "pam_unix_auth: USER NULL or empty!\n");
184  		return (PAM_USER_UNKNOWN);
185  	}
186  
187  	if (pam_get_item(pamh, PAM_AUTHTOK, (const void **)&passwd) !=
188  	    PAM_SUCCESS) {
189  		__pam_log(LOG_AUTH | LOG_DEBUG,
190  		    "pam_unix_auth: AUTHTOK not set!\n");
191  		return (PAM_SYSTEM_ERR);
192  	}
193  
194  	result = pam_get_item(pamh, PAM_REPOSITORY, (const void **)&auth_rep);
195  	if (result == PAM_SUCCESS && auth_rep != NULL) {
196  		if ((pwu_rep = calloc(1, sizeof (*pwu_rep))) == NULL)
197  			return (PAM_BUF_ERR);
198  		pwu_rep->type = auth_rep->type;
199  		pwu_rep->scope = auth_rep->scope;
200  		pwu_rep->scope_len = auth_rep->scope_len;
201  	} else {
202  		pwu_rep = PWU_DEFAULT_REP;
203  	}
204  
205  	/*
206  	 * Get password and the name of the repository where the
207  	 * password resides.
208  	 */
209  	attr_pw[0].type = ATTR_PASSWD;		attr_pw[0].next = &attr_pw[1];
210  	attr_pw[1].type = ATTR_REP_NAME;	attr_pw[1].next = &attr_pw[2];
211  	/*
212  	 * Also get the current number of failed logins; we use
213  	 * this later to determine whether we need to reset the count
214  	 * on a succesful authentication. We use the home-directory
215  	 * to look for .hushlogin in order to optionaly surpress the
216  	 * "failed attempts" message.
217  	 */
218  	attr_pw[2].type = ATTR_FAILED_LOGINS;	attr_pw[2].next = &attr_pw[3];
219  	attr_pw[3].type = ATTR_HOMEDIR;		attr_pw[3].next = NULL;
220  
221  	result = __get_authtoken_attr(user, pwu_rep, attr_pw);
222  
223  	if (pwu_rep != PWU_DEFAULT_REP)
224  		free(pwu_rep);
225  
226  	if (result == PWU_NOT_FOUND) {
227  		__pam_log(LOG_AUTH | LOG_DEBUG,
228  		    "pam_unix_auth: user %s not found\n", user);
229  		return (PAM_USER_UNKNOWN);
230  	}
231  
232  	if (result == PWU_DENIED) {
233  		__pam_log(LOG_AUTH | LOG_DEBUG,
234  		    "pam_unix_auth: failed to obtain attributes");
235  		return (PAM_PERM_DENIED);
236  	}
237  
238  	if (result != PWU_SUCCESS)
239  		return (PAM_SYSTEM_ERR);
240  
241  	rep_passwd = attr_pw[0].data.val_s;
242  	repository_name = attr_pw[1].data.val_s;
243  	old_failed_count = attr_pw[2].data.val_i;
244  	homedir = attr_pw[3].data.val_s;
245  
246  	/*
247  	 * Chop off old SunOS-style password aging information.
248  	 *
249  	 * Note: old style password aging is only defined for UNIX-style
250  	 *	 crypt strings, hence the comma will always be at position 14.
251  	 * Note: This code is here because some other vendors might still
252  	 *	 support this style of password aging. If we don't remove
253  	 *	 the age field, no one will be able to login.
254  	 * XXX   yank this code when we're certain this "compatibility"
255  	 *	 isn't needed anymore.
256  	 */
257  	if (rep_passwd != NULL && rep_passwd[0] != '$' &&
258  	    strlen(rep_passwd) > 13 && rep_passwd[13] == ',')
259  		rep_passwd[13] = '\0';
260  
261  	/* Is a password check required? */
262  	if (rep_passwd == NULL || *rep_passwd == '\0') {
263  		if (flags & PAM_DISALLOW_NULL_AUTHTOK) {
264  			result = PAM_AUTH_ERR;
265  			__pam_log(LOG_AUTH | LOG_NOTICE,
266  			    "pam_unix_auth: empty password for %s not allowed.",
267  			    user);
268  			goto out;
269  		} else {
270  			result = PAM_SUCCESS;
271  			goto out;
272  		}
273  	}
274  
275  	/*
276  	 * Password check *is* required. Make sure we have a valid
277  	 * pointer in PAM_AUTHTOK
278  	 */
279  	if (passwd == NULL) {
280  		result = PAM_AUTH_ERR;
281  		goto out;
282  	}
283  
284  	if (server_policy &&
285  	    strcmp(repository_name, "files") != 0 &&
286  	    strcmp(repository_name, "nis") != 0) {
287  		result = PAM_IGNORE;
288  		goto out;
289  	}
290  
291  	/* Now check the entered password */
292  	if ((crypt_passwd = crypt(passwd, rep_passwd)) == NULL) {
293  		switch (errno) {
294  		case ENOMEM:
295  			result = PAM_BUF_ERR;
296  			break;
297  		case ELIBACC:
298  			result = PAM_OPEN_ERR;
299  			break;
300  		default:
301  			result = PAM_SYSTEM_ERR;
302  		}
303  		goto out;
304  	}
305  
306  	if (strcmp(crypt_passwd, rep_passwd) == 0)
307  		result = PAM_SUCCESS;
308  	else
309  		result = PAM_AUTH_ERR;
310  
311  	/* Clear or increment failed failed count */
312  	if (dolock && (result == PAM_SUCCESS && old_failed_count > 0)) {
313  		old_failed_count = __rst_failed_count(user, repository_name);
314  		if (nowarn == 0 && old_failed_count > 0)
315  			display_warning(pamh, old_failed_count, homedir);
316  	} else if (dolock && result == PAM_AUTH_ERR) {
317  		int max_failed = get_max_failed(user);
318  		if (max_failed != 0) {
319  			if (__incr_failed_count(user, repository_name,
320  			    max_failed) == PWU_ACCOUNT_LOCKED)
321  				result = PAM_MAXTRIES;
322  		}
323  	}
324  out:
325  	if (rep_passwd)
326  		free(rep_passwd);
327  	if (repository_name)
328  		free(repository_name);
329  	if (homedir)
330  		free(homedir);
331  	return (result);
332  }
333  
334  /*ARGSUSED*/
335  int
336  pam_sm_setcred(pam_handle_t *pamh, int flags, int argc, const char **argv)
337  {
338  	return (PAM_IGNORE);
339  }
340