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 */
50int
51test_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