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/cdefs.h> 29 #include <sys/param.h> 30 #include <sys/capsicum.h> 31 #include <sys/errno.h> 32 33 #include <err.h> 34 #include <fcntl.h> 35 #include <stdlib.h> 36 #include <string.h> 37 #include <unistd.h> 38 39 #include "cap_test.h" 40 41 /* 42 * Test openat(2) in a variety of sitations to ensure that it obeys Capsicum 43 * "strict relative" rules: 44 * 45 * 1. Use strict relative lookups in capability mode or when operating 46 * relative to a capability. 47 * 2. When performing strict relative lookups, absolute paths (including 48 * symlinks to absolute paths) are not allowed, nor are paths containing 49 * '..' components. 50 */ 51 int 52 test_relative(void) 53 { 54 int success = PASSED; 55 int fd, etc, etc_cap, etc_cap_ro, etc_cap_base, etc_cap_all; 56 cap_rights_t baserights = CAP_READ | CAP_WRITE | CAP_SEEK | CAP_LOOKUP; 57 cap_rights_t rights; 58 59 REQUIRE(etc = open("/etc/", O_RDONLY)); 60 CHECK_SYSCALL_SUCCEEDS(cap_getrights, etc, &rights); 61 CHECK_RIGHTS(rights, CAP_ALL); 62 63 MAKE_CAPABILITY(etc_cap, etc, CAP_READ); 64 MAKE_CAPABILITY(etc_cap_ro, etc, CAP_READ | CAP_LOOKUP); 65 MAKE_CAPABILITY(etc_cap_base, etc, baserights); 66 MAKE_CAPABILITY(etc_cap_all, etc, CAP_MASK_VALID); 67 68 /* 69 * openat(2) with regular file descriptors in non-capability mode 70 * should Just Work (tm). 71 */ 72 CHECK_SYSCALL_SUCCEEDS(openat, etc, "/etc/passwd", O_RDONLY); 73 CHECK_SYSCALL_SUCCEEDS(openat, AT_FDCWD, "/etc/passwd", O_RDONLY); 74 CHECK_SYSCALL_SUCCEEDS(openat, etc, "passwd", O_RDONLY); 75 CHECK_SYSCALL_SUCCEEDS(openat, etc, "../etc/passwd", O_RDONLY); 76 77 /* 78 * Lookups relative to capabilities should be strictly relative. 79 * 80 * When not in capability mode, we don't actually require CAP_LOOKUP. 81 */ 82 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_ro, "passwd", O_RDONLY); 83 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_base, "passwd", O_RDONLY); 84 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_all, "passwd", O_RDONLY); 85 86 CHECK_NOTCAPABLE(openat, etc_cap_ro, "../etc/passwd", O_RDONLY); 87 CHECK_NOTCAPABLE(openat, etc_cap_base, "../etc/passwd", O_RDONLY); 88 89 /* 90 * This requires discussion: do we treat a capability with 91 * CAP_MASK_VALID *exactly* like a non-capability file descriptor 92 * (currently, the implementation says yes)? 93 */ 94 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_all, "../etc/passwd", O_RDONLY); 95 96 /* 97 * A file opened relative to a capability should itself be a capability. 98 */ 99 CHECK_SYSCALL_SUCCEEDS(cap_getrights, etc_cap_base, &rights); 100 101 REQUIRE(fd = openat(etc_cap_base, "passwd", O_RDONLY)); 102 CHECK_SYSCALL_SUCCEEDS(cap_getrights, fd, &rights); 103 CHECK_RIGHTS(rights, baserights); 104 105 /* 106 * Enter capability mode; now ALL lookups are strictly relative. 107 */ 108 REQUIRE(cap_enter()); 109 110 /* 111 * Relative lookups on regular files or capabilities with CAP_LOOKUP 112 * ought to succeed. 113 */ 114 CHECK_SYSCALL_SUCCEEDS(openat, etc, "passwd", O_RDONLY); 115 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_ro, "passwd", O_RDONLY); 116 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_base, "passwd", O_RDONLY); 117 CHECK_SYSCALL_SUCCEEDS(openat, etc_cap_all, "passwd", O_RDONLY); 118 119 /* 120 * Lookup relative to capabilities without CAP_LOOKUP should fail. 121 */ 122 CHECK_NOTCAPABLE(openat, etc_cap, "passwd", O_RDONLY); 123 124 /* 125 * Absolute lookups should fail. 126 */ 127 CHECK_CAPMODE(openat, AT_FDCWD, "/etc/passwd", O_RDONLY); 128 CHECK_NOTCAPABLE(openat, etc, "/etc/passwd", O_RDONLY); 129 130 /* 131 * Lookups containing '..' should fail in capability mode. 132 */ 133 CHECK_NOTCAPABLE(openat, etc, "../etc/passwd", O_RDONLY); 134 CHECK_NOTCAPABLE(openat, etc_cap_ro, "../etc/passwd", O_RDONLY); 135 CHECK_NOTCAPABLE(openat, etc_cap_base, "../etc/passwd", O_RDONLY); 136 137 REQUIRE(fd = openat(etc, "passwd", O_RDONLY)); 138 CHECK_SYSCALL_SUCCEEDS(cap_getrights, fd, &rights); 139 140 /* 141 * A file opened relative to a capability should itself be a capability. 142 */ 143 REQUIRE(fd = openat(etc_cap_base, "passwd", O_RDONLY)); 144 CHECK_SYSCALL_SUCCEEDS(cap_getrights, fd, &rights); 145 CHECK_RIGHTS(rights, baserights); 146 147 return success; 148 } 149