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
pam_sm_authenticate(pam_handle_t * pamh,int flags __unused,int argc __unused,const char * argv[]__unused)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
pam_sm_setcred(pam_handle_t * pamh __unused,int flags __unused,int argc __unused,const char * argv[]__unused)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