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
28 #include <sys/param.h>
29 #include <sys/capsicum.h>
30 #include <sys/errno.h>
31
32 #include <err.h>
33 #include <fcntl.h>
34 #include <stdlib.h>
35 #include <string.h>
36 #include <unistd.h>
37
38 #include "cap_test.h"
39
40 /*
41 * Test openat(2) in a variety of sitations to ensure that it obeys Capsicum
42 * "strict relative" rules:
43 *
44 * 1. Use strict relative lookups in capability mode or when operating
45 * relative to a capability.
46 * 2. When performing strict relative lookups, absolute paths (including
47 * symlinks to absolute paths) are not allowed, nor are paths containing
48 * '..' components.
49 */
50 int
test_relative(void)51 test_relative(void)
52 {
53 int success = PASSED;
54 int fd, etc, etc_cap, etc_cap_ro, etc_cap_base, etc_cap_all;
55 cap_rights_t baserights = CAP_READ | CAP_WRITE | CAP_SEEK | CAP_LOOKUP;
56 cap_rights_t rights;
57
58 REQUIRE(etc = open("/etc/", O_RDONLY));
59 CHECK_SYSCALL_SUCCEEDS(cap_getrights, etc, &rights);
60 CHECK_RIGHTS(rights, CAP_ALL);
61
62 MAKE_CAPABILITY(etc_cap, etc, CAP_READ);
63 MAKE_CAPABILITY(etc_cap_ro, etc, CAP_READ | CAP_LOOKUP);
64 MAKE_CAPABILITY(etc_cap_base, etc, baserights);
65 MAKE_CAPABILITY(etc_cap_all, etc, CAP_MASK_VALID);
66
67 /*
68 * openat(2) with regular file descriptors in non-capability mode
69 * should Just Work (tm).
70 */
71 CHECK_SYSCALL_SUCCEEDS(openat, etc, "/etc/passwd", O_RDONLY);
72 CHECK_SYSCALL_SUCCEEDS(openat, AT_FDCWD, "/etc/passwd", O_RDONLY);
73 CHECK_SYSCALL_SUCCEEDS(openat, etc, "passwd", O_RDONLY);
74 CHECK_SYSCALL_SUCCEEDS(openat, etc, "../etc/passwd", O_RDONLY);
75
76 /*
77 * Lookups relative to capabilities should be strictly relative.
78 *
79 * When not in capability mode, we don't actually require CAP_LOOKUP.
80 */
81 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_ro, "passwd", O_RDONLY);
82 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_base, "passwd", O_RDONLY);
83 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_all, "passwd", O_RDONLY);
84
85 CHECK_NOTCAPABLE(openat, etc_cap_ro, "../etc/passwd", O_RDONLY);
86 CHECK_NOTCAPABLE(openat, etc_cap_base, "../etc/passwd", O_RDONLY);
87
88 /*
89 * This requires discussion: do we treat a capability with
90 * CAP_MASK_VALID *exactly* like a non-capability file descriptor
91 * (currently, the implementation says yes)?
92 */
93 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_all, "../etc/passwd", O_RDONLY);
94
95 /*
96 * A file opened relative to a capability should itself be a capability.
97 */
98 CHECK_SYSCALL_SUCCEEDS(cap_getrights, etc_cap_base, &rights);
99
100 REQUIRE(fd = openat(etc_cap_base, "passwd", O_RDONLY));
101 CHECK_SYSCALL_SUCCEEDS(cap_getrights, fd, &rights);
102 CHECK_RIGHTS(rights, baserights);
103
104 /*
105 * Enter capability mode; now ALL lookups are strictly relative.
106 */
107 REQUIRE(cap_enter());
108
109 /*
110 * Relative lookups on regular files or capabilities with CAP_LOOKUP
111 * ought to succeed.
112 */
113 CHECK_SYSCALL_SUCCEEDS(openat, etc, "passwd", O_RDONLY);
114 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_ro, "passwd", O_RDONLY);
115 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_base, "passwd", O_RDONLY);
116 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_all, "passwd", O_RDONLY);
117
118 /*
119 * Lookup relative to capabilities without CAP_LOOKUP should fail.
120 */
121 CHECK_NOTCAPABLE(openat, etc_cap, "passwd", O_RDONLY);
122
123 /*
124 * Absolute lookups should fail.
125 */
126 CHECK_CAPMODE(openat, AT_FDCWD, "/etc/passwd", O_RDONLY);
127 CHECK_NOTCAPABLE(openat, etc, "/etc/passwd", O_RDONLY);
128
129 /*
130 * Lookups containing '..' should fail in capability mode.
131 */
132 CHECK_NOTCAPABLE(openat, etc, "../etc/passwd", O_RDONLY);
133 CHECK_NOTCAPABLE(openat, etc_cap_ro, "../etc/passwd", O_RDONLY);
134 CHECK_NOTCAPABLE(openat, etc_cap_base, "../etc/passwd", O_RDONLY);
135
136 REQUIRE(fd = openat(etc, "passwd", O_RDONLY));
137 CHECK_SYSCALL_SUCCEEDS(cap_getrights, fd, &rights);
138
139 /*
140 * A file opened relative to a capability should itself be a capability.
141 */
142 REQUIRE(fd = openat(etc_cap_base, "passwd", O_RDONLY));
143 CHECK_SYSCALL_SUCCEEDS(cap_getrights, fd, &rights);
144 CHECK_RIGHTS(rights, baserights);
145
146 return success;
147 }
148