pam_nologin.c revision 1.3 
1/*	$NetBSD: pam_nologin.c,v 1.3 2005/01/23 09:45:02 manu 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 1.3 2005/01/23 09:45:02 manu 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
66static char nologin_def[] = NOLOGIN;
67
68PAM_EXTERN int
69pam_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;
74	struct stat st;
75	int retval, fd;
76	int ignorenologin = 0;
77	int rootlogin = 0;
78	const char *user, *nologin;
79	char *mtmp;
80
81	if ((retval = pam_get_user(pamh, &user, NULL)) != PAM_SUCCESS)
82		return retval;
83
84	PAM_LOG("Got user: %s", user);
85
86	/*
87	 * For root, the default is to ignore nologin, but the
88	 * ignorenologin capability can override this, so we
89	 * set the default appropriately.
90	 *
91	 * Do not allow login of unexisting users, so that a directory
92	 * failure will not cause the nologin capability to be ignored.
93	 */
94	if ((pwd = getpwnam(user)) == NULL) {
95		return PAM_USER_UNKNOWN;
96	} else {
97		if (pwd->pw_uid == 0)
98			rootlogin = 1;
99	}
100
101	lc = login_getclass(NULL);
102	ignorenologin = login_getcapbool(lc, "ignorenologin", rootlogin);
103	nologin = login_getcapstr(lc, "nologin", nologin_def, nologin_def);
104	login_close(lc);
105	lc = NULL;
106
107	if (ignorenologin)
108		return PAM_SUCCESS;
109
110	if ((fd = open(nologin, O_RDONLY, 0)) == -1) {
111		/*
112		 * The file does not exist, login is granted
113		 */
114		if (errno == ENOENT)
115			return PAM_SUCCESS;
116
117		/*
118		 * open failed, but the file exists. This could be
119		 * a temporary problem (system resources exausted):
120		 * Refuse the login.
121		 */
122		PAM_LOG("Cannot open %s file: %s", nologin, strerror(errno));
123		return PAM_AUTH_ERR;
124	}
125
126	PAM_LOG("Opened %s file", nologin);
127
128	if (fstat(fd, &st) < 0)
129		return PAM_AUTH_ERR;
130
131	mtmp = malloc(st.st_size + 1);
132	if (mtmp != NULL) {
133		read(fd, mtmp, st.st_size);
134		mtmp[st.st_size] = '\0';
135		pam_error(pamh, "%s", mtmp, NULL);
136		free(mtmp);
137	}
138
139	PAM_VERBOSE_ERROR("Administrator refusing you: %s", nologin);
140
141	return PAM_AUTH_ERR;
142}
143
144PAM_EXTERN int
145pam_sm_setcred(pam_handle_t *pamh __unused, int flags __unused,
146    int argc __unused, const char *argv[] __unused)
147{
148
149	return (PAM_SUCCESS);
150}
151
152PAM_MODULE_ENTRY("pam_nologin");
153