1 /*-
2 * Copyright (c) 2011 Dag-Erling Smørgrav
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
55 int
openpam_check_desc_owner_perms(const char * name,int fd)56 openpam_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
98 int
openpam_check_path_owner_perms(const char * path)99 openpam_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