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 * $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
57 int
openpam_check_desc_owner_perms(const char * name,int fd)58 openpam_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
100 int
openpam_check_path_owner_perms(const char * path)101 openpam_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