cap_test_relative.c revision 224793 
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: head/tools/regression/security/cap_test/cap_test_relative.c 224793 2011-08-12 10:52:46Z jonathan $
28 */
29
30#include <sys/cdefs.h>
31__FBSDID("$FreeBSD: head/tools/regression/security/cap_test/cap_test_relative.c 224793 2011-08-12 10:52:46Z jonathan $");
32
33#include <sys/param.h>
34#include <sys/capability.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 */
55int
56test_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_FAILS(EINVAL, cap_getrights, etc, &rights);
65
66	MAKE_CAPABILITY(etc_cap, etc, CAP_READ);
67	MAKE_CAPABILITY(etc_cap_ro, etc, CAP_READ | CAP_LOOKUP);
68	MAKE_CAPABILITY(etc_cap_base, etc, baserights);
69	MAKE_CAPABILITY(etc_cap_all, etc, CAP_MASK_VALID);
70
71	/*
72	 * openat(2) with regular file descriptors in non-capability mode
73	 * should Just Work (tm).
74	 */
75	CHECK_SYSCALL_SUCCEEDS(openat, etc, "/etc/passwd", O_RDONLY);
76	CHECK_SYSCALL_SUCCEEDS(openat, AT_FDCWD, "/etc/passwd", O_RDONLY);
77	CHECK_SYSCALL_SUCCEEDS(openat, etc, "passwd", O_RDONLY);
78	CHECK_SYSCALL_SUCCEEDS(openat, etc, "../etc/passwd", O_RDONLY);
79
80	/*
81	 * Lookups relative to capabilities should be strictly relative.
82	 *
83	 * When not in capability mode, we don't actually require CAP_LOOKUP.
84	 */
85	CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_ro, "passwd", O_RDONLY);
86	CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_base, "passwd", O_RDONLY);
87	CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_all, "passwd", O_RDONLY);
88
89	CHECK_NOTCAPABLE(openat, etc_cap_ro, "../etc/passwd", O_RDONLY);
90	CHECK_NOTCAPABLE(openat, etc_cap_base, "../etc/passwd", O_RDONLY);
91
92	/*
93	 * This requires discussion: do we treat a capability with
94	 * CAP_MASK_VALID *exactly* like a non-capability file descriptor
95	 * (currently, the implementation says yes)?
96	 */
97	CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_all, "../etc/passwd", O_RDONLY);
98
99	/*
100	 * A file opened relative to a capability should itself be a capability.
101	 */
102	CHECK_SYSCALL_SUCCEEDS(cap_getrights, etc_cap_base, &rights);
103
104	REQUIRE(fd = openat(etc_cap_base, "passwd", O_RDONLY));
105	CHECK_SYSCALL_SUCCEEDS(cap_getrights, fd, &rights);
106	CHECK_RIGHTS(rights, baserights);
107
108	/*
109	 * Enter capability mode; now ALL lookups are strictly relative.
110	 */
111	REQUIRE(cap_enter());
112
113	/*
114	 * Relative lookups on regular files or capabilities with CAP_LOOKUP
115	 * ought to succeed.
116	 */
117	CHECK_SYSCALL_SUCCEEDS(openat, etc, "passwd", O_RDONLY);
118	CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_ro, "passwd", O_RDONLY);
119	CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_base, "passwd", O_RDONLY);
120	CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_all, "passwd", O_RDONLY);
121
122	/*
123	 * Lookup relative to capabilities without CAP_LOOKUP should fail.
124	 */
125	CHECK_NOTCAPABLE(openat, etc_cap, "passwd", O_RDONLY);
126
127	/*
128	 * Absolute lookups should fail.
129	 */
130	CHECK_CAPMODE(openat, AT_FDCWD, "/etc/passwd", O_RDONLY);
131	CHECK_NOTCAPABLE(openat, etc, "/etc/passwd", O_RDONLY);
132
133	/*
134	 * Lookups containing '..' should fail in capability mode.
135	 */
136	CHECK_NOTCAPABLE(openat, etc, "../etc/passwd", O_RDONLY);
137	CHECK_NOTCAPABLE(openat, etc_cap_ro, "../etc/passwd", O_RDONLY);
138	CHECK_NOTCAPABLE(openat, etc_cap_base, "../etc/passwd", O_RDONLY);
139
140	REQUIRE(fd = openat(etc, "passwd", O_RDONLY));
141	CHECK_SYSCALL_SUCCEEDS(cap_getrights, fd, &rights);
142
143	/*
144	 * A file opened relative to a capability should itself be a capability.
145	 */
146	REQUIRE(fd = openat(etc_cap_base, "passwd", O_RDONLY));
147	CHECK_SYSCALL_SUCCEEDS(cap_getrights, fd, &rights);
148	CHECK_RIGHTS(rights, baserights);
149
150	return success;
151}
152