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
30#ifdef HAVE_CONFIG_H
31# include "config.h"
32#endif
33
34#include <sys/types.h>
35#include <sys/stat.h>
36
37#include <errno.h>
38#include <limits.h>
39#include <stdlib.h>
40#include <string.h>
41#include <unistd.h>
42
43#include <security/pam_appl.h>
44
45#include "openpam_impl.h"
46
47/*
48 * OpenPAM internal
49 *
50 * Verify that the file or directory referenced by the given descriptor is
51 * owned by either root or the arbitrator and that it is not writable by
52 * group or other.
53 */
54
55int
56openpam_check_desc_owner_perms(const char *name, int fd)
57{
58	uid_t root, arbitrator;
59	struct stat sb;
60	int serrno;
61
62	root = 0;
63	arbitrator = geteuid();
64	if (fstat(fd, &sb) != 0) {
65		serrno = errno;
66		openpam_log(PAM_LOG_ERROR, "%s: %m", name);
67		errno = serrno;
68		return (-1);
69	}
70	if (!S_ISREG(sb.st_mode)) {
71		openpam_log(PAM_LOG_ERROR,
72		    "%s: not a regular file", name);
73		errno = EINVAL;
74		return (-1);
75	}
76	if ((sb.st_uid != root && sb.st_uid != arbitrator) ||
77	    (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
78		openpam_log(PAM_LOG_ERROR,
79		    "%s: insecure ownership or permissions", name);
80		errno = EPERM;
81		return (-1);
82	}
83	return (0);
84}
85
86/*
87 * OpenPAM internal
88 *
89 * Verify that a file or directory and all components of the path leading
90 * up to it are owned by either root or the arbitrator and that they are
91 * not writable by group or other.
92 *
93 * Note that openpam_check_desc_owner_perms() should be used instead if
94 * possible to avoid a race between the ownership / permission check and
95 * the actual open().
96 */
97
98int
99openpam_check_path_owner_perms(const char *path)
100{
101	uid_t root, arbitrator;
102	char pathbuf[PATH_MAX];
103	struct stat sb;
104	int len, serrno, tip;
105
106	tip = 1;
107	root = 0;
108	arbitrator = geteuid();
109	if (realpath(path, pathbuf) == NULL)
110		return (-1);
111	len = strlen(pathbuf);
112	while (len > 0) {
113		if (stat(pathbuf, &sb) != 0) {
114			if (errno != ENOENT) {
115				serrno = errno;
116				openpam_log(PAM_LOG_ERROR, "%s: %m", pathbuf);
117				errno = serrno;
118			}
119			return (-1);
120		}
121		if (tip && !S_ISREG(sb.st_mode)) {
122			openpam_log(PAM_LOG_ERROR,
123			    "%s: not a regular file", pathbuf);
124			errno = EINVAL;
125			return (-1);
126		}
127		if ((sb.st_uid != root && sb.st_uid != arbitrator) ||
128		    (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
129			openpam_log(PAM_LOG_ERROR,
130			    "%s: insecure ownership or permissions", pathbuf);
131			errno = EPERM;
132			return (-1);
133		}
134		while (--len > 0 && pathbuf[len] != '/')
135			pathbuf[len] = '\0';
136		tip = 0;
137	}
138	return (0);
139}
140
141/*
142 * NOPARSE
143 */
144