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      1 /*	$NetBSD: pam_nologin.c,v 1.10 2013/12/29 22:54:58 christos Exp $	*/
      2 
      3 /*-
      4  * Copyright 2001 Mark R V Murray
      5  * All rights reserved.
      6  * Copyright (c) 2001 Networks Associates Technology, Inc.
      7  * All rights reserved.
      8  *
      9  * Portions of this software were developed for the FreeBSD Project by
     10  * ThinkSec AS and NAI Labs, the Security Research Division of Network
     11  * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
     12  * ("CBOSS"), as part of the DARPA CHATS research program.
     13  *
     14  * Redistribution and use in source and binary forms, with or without
     15  * modification, are permitted provided that the following conditions
     16  * are met:
     17  * 1. Redistributions of source code must retain the above copyright
     18  *    notice, this list of conditions and the following disclaimer.
     19  * 2. Redistributions in binary form must reproduce the above copyright
     20  *    notice, this list of conditions and the following disclaimer in the
     21  *    documentation and/or other materials provided with the distribution.
     22  * 3. The name of the author may not be used to endorse or promote
     23  *    products derived from this software without specific prior written
     24  *    permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/cdefs.h>
     40 #ifdef __FreeBSD__
     41 __FBSDID("$FreeBSD: src/lib/libpam/modules/pam_nologin/pam_nologin.c,v 1.10 2002/04/12 22:27:21 des Exp $");
     42 #else
     43 __RCSID("$NetBSD: pam_nologin.c,v 1.10 2013/12/29 22:54:58 christos Exp $");
     44 #endif
     45 
     46 
     47 #include <sys/types.h>
     48 #include <sys/stat.h>
     49 #include <fcntl.h>
     50 #include <login_cap.h>
     51 #include <pwd.h>
     52 #include <errno.h>
     53 #include <string.h>
     54 #include <stdio.h>
     55 #include <stdlib.h>
     56 #include <unistd.h>
     57 
     58 #define PAM_SM_AUTH
     59 
     60 #include <security/pam_appl.h>
     61 #include <security/pam_modules.h>
     62 #include <security/pam_mod_misc.h>
     63 
     64 #define	NOLOGIN	"/etc/nologin"
     65 
     66 static char nologin_def[] = NOLOGIN;
     67 
     68 PAM_EXTERN int
     69 pam_sm_authenticate(pam_handle_t *pamh, int flags __unused,
     70     int argc __unused, const char *argv[] __unused)
     71 {
     72 	login_cap_t *lc;
     73 	struct passwd *pwd, pwres;
     74 	struct stat st;
     75 	int retval, fd;
     76 	int ignorenologin = 0;
     77 	u_int rootlogin = 0;
     78 	const char *user, *nologin;
     79 	char *mtmp;
     80 	char pwbuf[1024];
     81 
     82 	if ((retval = pam_get_user(pamh, &user, NULL)) != PAM_SUCCESS)
     83 		return retval;
     84 
     85 	PAM_LOG("Got user: %s", user);
     86 
     87 	/*
     88 	 * For root, the default is to ignore nologin, but the
     89 	 * ignorenologin capability can override this, so we
     90 	 * set the default appropriately.
     91 	 *
     92 	 * Do not allow login of unexisting users, so that a directory
     93 	 * failure will not cause the nologin capability to be ignored.
     94 	 */
     95 	if (getpwnam_r(user, &pwres, pwbuf, sizeof(pwbuf), &pwd) != 0 ||
     96 	    pwd == NULL) {
     97 		return PAM_USER_UNKNOWN;
     98 	} else {
     99 		if (pwd->pw_uid == 0)
    100 			rootlogin = 1;
    101 	}
    102 
    103 	lc = login_getpwclass(pwd);
    104 	ignorenologin = login_getcapbool(lc, "ignorenologin", rootlogin);
    105 	nologin = login_getcapstr(lc, "nologin", nologin_def, nologin_def);
    106 	login_close(lc);
    107 	lc = NULL;
    108 
    109 	if (ignorenologin)
    110 		return PAM_SUCCESS;
    111 
    112 	if ((fd = open(nologin, O_RDONLY, 0)) == -1) {
    113 		/*
    114 		 * The file does not exist, login is granted
    115 		 */
    116 		if (errno == ENOENT)
    117 			return PAM_SUCCESS;
    118 
    119 		/*
    120 		 * open failed, but the file exists. This could be
    121 		 * a temporary problem (system resources exausted):
    122 		 * Refuse the login.
    123 		 */
    124 		PAM_LOG("Cannot open %s file: %s", nologin, strerror(errno));
    125 		return PAM_AUTH_ERR;
    126 	}
    127 
    128 	PAM_LOG("Opened %s file", nologin);
    129 
    130 	if (fstat(fd, &st) < 0) {
    131 		close(fd);
    132 		return PAM_AUTH_ERR;
    133 	}
    134 
    135 	size_t len = (size_t)st.st_size;
    136 	mtmp = malloc(len + 1);
    137 	if (mtmp != NULL) {
    138 		read(fd, mtmp, len);
    139 		mtmp[len] = '\0';
    140 		pam_error(pamh, "%s", mtmp);
    141 		free(mtmp);
    142 	}
    143 	close(fd);
    144 
    145 	PAM_VERBOSE_ERROR("Administrator refusing you: %s", nologin);
    146 
    147 	return PAM_AUTH_ERR;
    148 }
    149 
    150 PAM_EXTERN int
    151 pam_sm_setcred(pam_handle_t *pamh __unused, int flags __unused,
    152     int argc __unused, const char *argv[] __unused)
    153 {
    154 
    155 	return (PAM_SUCCESS);
    156 }
    157 
    158 PAM_MODULE_ENTRY("pam_nologin");
    159