1/*-
2 * Copyright (c) 2011 Dag-Erling Sm��rgrav
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote
14 *    products derived from this software without specific prior written
15 *    permission.
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 * $OpenPAM: openpam_check_owner_perms.c 938 2017-04-30 21:34:42Z 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: %m", name);
69		errno = serrno;
70		return (-1);
71	}
72	if (!S_ISREG(sb.st_mode)) {
73		openpam_log(PAM_LOG_ERROR,
74		    "%s: not a regular file", name);
75		errno = EINVAL;
76		return (-1);
77	}
78	if ((sb.st_uid != root && sb.st_uid != arbitrator) ||
79	    (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
80		openpam_log(PAM_LOG_ERROR,
81		    "%s: insecure ownership or permissions", name);
82		errno = EPERM;
83		return (-1);
84	}
85	return (0);
86}
87
88/*
89 * OpenPAM internal
90 *
91 * Verify that a file or directory and all components of the path leading
92 * up to it are owned by either root or the arbitrator and that they are
93 * not writable by group or other.
94 *
95 * Note that openpam_check_desc_owner_perms() should be used instead if
96 * possible to avoid a race between the ownership / permission check and
97 * the actual open().
98 */
99
100int
101openpam_check_path_owner_perms(const char *path)
102{
103	uid_t root, arbitrator;
104	char pathbuf[PATH_MAX];
105	struct stat sb;
106	int len, serrno, tip;
107
108	tip = 1;
109	root = 0;
110	arbitrator = geteuid();
111	if (realpath(path, pathbuf) == NULL)
112		return (-1);
113	len = strlen(pathbuf);
114	while (len > 0) {
115		if (stat(pathbuf, &sb) != 0) {
116			if (errno != ENOENT) {
117				serrno = errno;
118				openpam_log(PAM_LOG_ERROR, "%s: %m", pathbuf);
119				errno = serrno;
120			}
121			return (-1);
122		}
123		if (tip && !S_ISREG(sb.st_mode)) {
124			openpam_log(PAM_LOG_ERROR,
125			    "%s: not a regular file", pathbuf);
126			errno = EINVAL;
127			return (-1);
128		}
129		if ((sb.st_uid != root && sb.st_uid != arbitrator) ||
130		    (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
131			openpam_log(PAM_LOG_ERROR,
132			    "%s: insecure ownership or permissions", pathbuf);
133			errno = EPERM;
134			return (-1);
135		}
136		while (--len > 0 && pathbuf[len] != '/')
137			pathbuf[len] = '\0';
138		tip = 0;
139	}
140	return (0);
141}
142
143/*
144 * NOPARSE
145 */
146