1/*	$NetBSD: openpam_check_owner_perms.c,v 1.4 2012/01/03 18:56:49 christos Exp $	*/
2
3/*-
4 * Copyright (c) 2011 Dag-Erling Smørgrav
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer
12 *    in this position and unchanged.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * Id: openpam_check_owner_perms.c 499 2011-11-22 11:51:50Z des
30 */
31
32#ifdef HAVE_CONFIG_H
33# include "config.h"
34#endif
35
36#include <sys/types.h>
37#include <sys/stat.h>
38
39#include <errno.h>
40#include <limits.h>
41#include <stdlib.h>
42#include <string.h>
43#include <unistd.h>
44
45#include <security/pam_appl.h>
46
47#include "openpam_impl.h"
48
49/*
50 * OpenPAM internal
51 *
52 * Verify that the file or directory referenced by the given descriptor is
53 * owned by either root or the arbitrator and that it is not writable by
54 * group or other.
55 */
56
57int
58openpam_check_desc_owner_perms(const char *name, int fd)
59{
60	uid_t root, arbitrator;
61	struct stat sb;
62	int serrno;
63
64	root = 0;
65	arbitrator = geteuid();
66	if (fstat(fd, &sb) != 0) {
67		serrno = errno;
68		openpam_log(PAM_LOG_ERROR, "%s: %s", name, strerror(errno));
69		errno = serrno;
70		return (-1);
71	}
72	if ((sb.st_uid != root && sb.st_uid != arbitrator) ||
73	    (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
74		openpam_log(PAM_LOG_ERROR,
75		    "%s: insecure ownership or permissions", name);
76		errno = EPERM;
77		return (-1);
78	}
79	return (0);
80}
81
82/*
83 * OpenPAM internal
84 *
85 * Verify that a file or directory and all components of the path leading
86 * up to it are owned by either root or the arbitrator and that they are
87 * not writable by group or other.
88 *
89 * Note that openpam_check_file_owner_perms() should be used instead if
90 * possible to avoid a race between the ownership / permission check and
91 * the actual open().
92 */
93
94int
95openpam_check_path_owner_perms(const char *path)
96{
97	uid_t root, arbitrator;
98	char pathbuf[PATH_MAX];
99	struct stat sb;
100	size_t len;
101	int serrno;
102
103	root = 0;
104	arbitrator = geteuid();
105	if (realpath(path, pathbuf) == NULL)
106		return (-1);
107	len = strlen(pathbuf);
108	while (len > 0) {
109		if (stat(pathbuf, &sb) != 0) {
110			serrno = errno;
111			openpam_log(PAM_LOG_ERROR, "%s: %s", pathbuf,
112			    strerror(errno));
113			errno = serrno;
114			return (-1);
115		}
116		if ((sb.st_uid != root && sb.st_uid != arbitrator) ||
117		    (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
118			openpam_log(PAM_LOG_ERROR,
119			    "%s: insecure ownership or permissions", pathbuf);
120			errno = EPERM;
121			return (-1);
122		}
123		while (--len > 0 && pathbuf[len] != '/')
124			pathbuf[len] = '\0';
125	}
126	return (0);
127}
128
129/*
130 * NOPARSE
131 */
132