1 /*-
2 * Copyright (c) 2009-2011 Robert N. M. Watson
3 * Copyright (c) 2011 Jonathan Anderson
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 * $FreeBSD: stable/12/tools/regression/security/cap_test/cap_test_relative.c 263234 2014-03-16 11:04:44Z rwatson $
28 */
29
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD: stable/12/tools/regression/security/cap_test/cap_test_relative.c 263234 2014-03-16 11:04:44Z rwatson $");
32
33 #include <sys/param.h>
34 #include <sys/capsicum.h>
35 #include <sys/errno.h>
36
37 #include <err.h>
38 #include <fcntl.h>
39 #include <stdlib.h>
40 #include <string.h>
41 #include <unistd.h>
42
43 #include "cap_test.h"
44
45 /*
46 * Test openat(2) in a variety of sitations to ensure that it obeys Capsicum
47 * "strict relative" rules:
48 *
49 * 1. Use strict relative lookups in capability mode or when operating
50 * relative to a capability.
51 * 2. When performing strict relative lookups, absolute paths (including
52 * symlinks to absolute paths) are not allowed, nor are paths containing
53 * '..' components.
54 */
55 int
test_relative(void)56 test_relative(void)
57 {
58 int success = PASSED;
59 int fd, etc, etc_cap, etc_cap_ro, etc_cap_base, etc_cap_all;
60 cap_rights_t baserights = CAP_READ | CAP_WRITE | CAP_SEEK | CAP_LOOKUP;
61 cap_rights_t rights;
62
63 REQUIRE(etc = open("/etc/", O_RDONLY));
64 CHECK_SYSCALL_SUCCEEDS(cap_getrights, etc, &rights);
65 CHECK_RIGHTS(rights, CAP_ALL);
66
67 MAKE_CAPABILITY(etc_cap, etc, CAP_READ);
68 MAKE_CAPABILITY(etc_cap_ro, etc, CAP_READ | CAP_LOOKUP);
69 MAKE_CAPABILITY(etc_cap_base, etc, baserights);
70 MAKE_CAPABILITY(etc_cap_all, etc, CAP_MASK_VALID);
71
72 /*
73 * openat(2) with regular file descriptors in non-capability mode
74 * should Just Work (tm).
75 */
76 CHECK_SYSCALL_SUCCEEDS(openat, etc, "/etc/passwd", O_RDONLY);
77 CHECK_SYSCALL_SUCCEEDS(openat, AT_FDCWD, "/etc/passwd", O_RDONLY);
78 CHECK_SYSCALL_SUCCEEDS(openat, etc, "passwd", O_RDONLY);
79 CHECK_SYSCALL_SUCCEEDS(openat, etc, "../etc/passwd", O_RDONLY);
80
81 /*
82 * Lookups relative to capabilities should be strictly relative.
83 *
84 * When not in capability mode, we don't actually require CAP_LOOKUP.
85 */
86 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_ro, "passwd", O_RDONLY);
87 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_base, "passwd", O_RDONLY);
88 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_all, "passwd", O_RDONLY);
89
90 CHECK_NOTCAPABLE(openat, etc_cap_ro, "../etc/passwd", O_RDONLY);
91 CHECK_NOTCAPABLE(openat, etc_cap_base, "../etc/passwd", O_RDONLY);
92
93 /*
94 * This requires discussion: do we treat a capability with
95 * CAP_MASK_VALID *exactly* like a non-capability file descriptor
96 * (currently, the implementation says yes)?
97 */
98 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_all, "../etc/passwd", O_RDONLY);
99
100 /*
101 * A file opened relative to a capability should itself be a capability.
102 */
103 CHECK_SYSCALL_SUCCEEDS(cap_getrights, etc_cap_base, &rights);
104
105 REQUIRE(fd = openat(etc_cap_base, "passwd", O_RDONLY));
106 CHECK_SYSCALL_SUCCEEDS(cap_getrights, fd, &rights);
107 CHECK_RIGHTS(rights, baserights);
108
109 /*
110 * Enter capability mode; now ALL lookups are strictly relative.
111 */
112 REQUIRE(cap_enter());
113
114 /*
115 * Relative lookups on regular files or capabilities with CAP_LOOKUP
116 * ought to succeed.
117 */
118 CHECK_SYSCALL_SUCCEEDS(openat, etc, "passwd", O_RDONLY);
119 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_ro, "passwd", O_RDONLY);
120 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_base, "passwd", O_RDONLY);
121 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_all, "passwd", O_RDONLY);
122
123 /*
124 * Lookup relative to capabilities without CAP_LOOKUP should fail.
125 */
126 CHECK_NOTCAPABLE(openat, etc_cap, "passwd", O_RDONLY);
127
128 /*
129 * Absolute lookups should fail.
130 */
131 CHECK_CAPMODE(openat, AT_FDCWD, "/etc/passwd", O_RDONLY);
132 CHECK_NOTCAPABLE(openat, etc, "/etc/passwd", O_RDONLY);
133
134 /*
135 * Lookups containing '..' should fail in capability mode.
136 */
137 CHECK_NOTCAPABLE(openat, etc, "../etc/passwd", O_RDONLY);
138 CHECK_NOTCAPABLE(openat, etc_cap_ro, "../etc/passwd", O_RDONLY);
139 CHECK_NOTCAPABLE(openat, etc_cap_base, "../etc/passwd", O_RDONLY);
140
141 REQUIRE(fd = openat(etc, "passwd", O_RDONLY));
142 CHECK_SYSCALL_SUCCEEDS(cap_getrights, fd, &rights);
143
144 /*
145 * A file opened relative to a capability should itself be a capability.
146 */
147 REQUIRE(fd = openat(etc_cap_base, "passwd", O_RDONLY));
148 CHECK_SYSCALL_SUCCEEDS(cap_getrights, fd, &rights);
149 CHECK_RIGHTS(rights, baserights);
150
151 return success;
152 }
153