pam_chroot.c revision 331722 
1/*-
2 * Copyright (c) 2003 Networks Associates Technology, Inc.
3 * All rights reserved.
4 *
5 * This software was developed for the FreeBSD Project by ThinkSec AS and
6 * NAI Labs, the Security Research Division of Network Associates, Inc.
7 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
8 * DARPA CHATS research program.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. The name of the author may not be used to endorse or promote
19 *    products derived from this software without specific prior written
20 *    permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <sys/cdefs.h>
36__FBSDID("$FreeBSD: stable/11/lib/libpam/modules/pam_chroot/pam_chroot.c 331722 2018-03-29 02:50:57Z eadler $");
37
38#include <sys/param.h>
39
40#include <pwd.h>
41#include <stdio.h>
42#include <string.h>
43#include <unistd.h>
44
45#define PAM_SM_SESSION
46
47#include <security/pam_appl.h>
48#include <security/pam_modules.h>
49#include <security/openpam.h>
50
51PAM_EXTERN int
52pam_sm_open_session(pam_handle_t *pamh, int flags __unused,
53    int argc __unused, const char *argv[] __unused)
54{
55	const char *dir, *end, *cwd, *user;
56	struct passwd *pwd;
57	char buf[PATH_MAX];
58
59	if (pam_get_user(pamh, &user, NULL) != PAM_SUCCESS ||
60	    user == NULL || (pwd = getpwnam(user)) == NULL)
61		return (PAM_SESSION_ERR);
62	if (pwd->pw_uid == 0 && !openpam_get_option(pamh, "also_root"))
63		return (PAM_SUCCESS);
64	if (pwd->pw_dir == NULL)
65		return (PAM_SESSION_ERR);
66	if ((end = strstr(pwd->pw_dir, "/./")) != NULL) {
67		if (snprintf(buf, sizeof(buf), "%.*s",
68		    (int)(end - pwd->pw_dir), pwd->pw_dir) > (int)sizeof(buf)) {
69			openpam_log(PAM_LOG_ERROR,
70			    "%s's home directory is too long", user);
71			return (PAM_SESSION_ERR);
72		}
73		dir = buf;
74		cwd = end + 2;
75	} else if ((dir = openpam_get_option(pamh, "dir")) != NULL) {
76		if ((cwd = openpam_get_option(pamh, "cwd")) == NULL)
77			cwd = "/";
78	} else {
79		if (openpam_get_option(pamh, "always")) {
80			openpam_log(PAM_LOG_ERROR,
81			    "%s has no chroot directory", user);
82			return (PAM_SESSION_ERR);
83		}
84		return (PAM_SUCCESS);
85	}
86
87	openpam_log(PAM_LOG_DEBUG, "chrooting %s to %s", dir, user);
88
89	if (chroot(dir) == -1) {
90		openpam_log(PAM_LOG_ERROR, "chroot(): %m");
91		return (PAM_SESSION_ERR);
92	}
93	if (chdir(cwd) == -1) {
94		openpam_log(PAM_LOG_ERROR, "chdir(): %m");
95		return (PAM_SESSION_ERR);
96	}
97	pam_setenv(pamh, "HOME", cwd, 1);
98	return (PAM_SUCCESS);
99}
100
101PAM_EXTERN int
102pam_sm_close_session(pam_handle_t *pamh __unused, int flags __unused,
103    int argc __unused, const char *argv[] __unused)
104{
105
106	return (PAM_SUCCESS);
107}
108
109PAM_MODULE_ENTRY("pam_chroot");
110