pam_chroot.c revision 1.2 
1/*	$NetBSD: pam_chroot.c,v 1.2 2004/12/12 08:18:43 christos Exp $	*/
2
3/*-
4 * Copyright (c) 2003 Networks Associates Technology, Inc.
5 * All rights reserved.
6 *
7 * This software was developed for the FreeBSD Project by ThinkSec AS and
8 * NAI Labs, the Security Research Division of Network Associates, Inc.
9 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
10 * DARPA CHATS research program.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 *    notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 *    notice, this list of conditions and the following disclaimer in the
19 *    documentation and/or other materials provided with the distribution.
20 * 3. The name of the author may not be used to endorse or promote
21 *    products derived from this software without specific prior written
22 *    permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#include <sys/cdefs.h>
38#ifdef __FreeBSD__
39__FBSDID("$FreeBSD: src/lib/libpam/modules/pam_chroot/pam_chroot.c,v 1.3 2003/04/30 00:40:24 des Exp $");
40#else
41__RCSID("$NetBSD: pam_chroot.c,v 1.2 2004/12/12 08:18:43 christos Exp $");
42#endif
43
44#include <sys/param.h>
45
46#include <pwd.h>
47#include <stdio.h>
48#include <string.h>
49#include <unistd.h>
50
51#define PAM_SM_SESSION
52
53#include <security/pam_appl.h>
54#include <security/pam_modules.h>
55#include <security/openpam.h>
56
57PAM_EXTERN int
58pam_sm_open_session(pam_handle_t *pamh, int flags __unused,
59    int argc __unused, const char *argv[] __unused)
60{
61	const char *dir, *end, *cwd, *user;
62	struct passwd *pwd;
63	char buf[PATH_MAX];
64
65	if (pam_get_user(pamh, &user, NULL) != PAM_SUCCESS ||
66	    user == NULL || (pwd = getpwnam(user)) == NULL)
67		return (PAM_SESSION_ERR);
68	if (pwd->pw_uid == 0 && !openpam_get_option(pamh, "also_root"))
69		return (PAM_SUCCESS);
70	if (pwd->pw_dir == NULL)
71		return (PAM_SESSION_ERR);
72	if ((end = strstr(pwd->pw_dir, "/./")) != NULL) {
73		if (snprintf(buf, sizeof(buf), "%.*s",
74		    (int)(end - pwd->pw_dir), pwd->pw_dir) > (int)sizeof(buf)) {
75			openpam_log(PAM_LOG_ERROR,
76			    "%s's home directory is too long", user);
77			return (PAM_SESSION_ERR);
78		}
79		dir = buf;
80		cwd = end + 2;
81	} else if ((dir = openpam_get_option(pamh, "dir")) != NULL) {
82		if ((cwd = openpam_get_option(pamh, "cwd")) == NULL)
83			cwd = "/";
84	} else {
85		if (openpam_get_option(pamh, "always")) {
86			openpam_log(PAM_LOG_ERROR,
87			    "%s has no chroot directory", user);
88			return (PAM_SESSION_ERR);
89		}
90		return (PAM_SUCCESS);
91	}
92
93	openpam_log(PAM_LOG_DEBUG, "chrooting %s to %s", dir, user);
94
95	if (chroot(dir) == -1) {
96		openpam_log(PAM_LOG_ERROR, "chroot(): %m");
97		return (PAM_SESSION_ERR);
98	}
99	if (chdir(cwd) == -1) {
100		openpam_log(PAM_LOG_ERROR, "chdir(): %m");
101		return (PAM_SESSION_ERR);
102	}
103	pam_setenv(pamh, "HOME", cwd, 1);
104	return (PAM_SUCCESS);
105}
106
107PAM_EXTERN int
108pam_sm_close_session(pam_handle_t *pamh __unused, int flags __unused,
109    int argc __unused, const char *argv[] __unused)
110{
111
112	return (PAM_SUCCESS);
113}
114
115PAM_MODULE_ENTRY("pam_chroot");
116