1 /* $NetBSD: t_ptrace.c,v 1.18 2017/01/13 21:30:41 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2016 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __RCSID("$NetBSD: t_ptrace.c,v 1.18 2017/01/13 21:30:41 christos Exp $"); 31 32 #include <sys/param.h> 33 #include <sys/types.h> 34 #include <sys/ptrace.h> 35 #include <sys/stat.h> 36 #include <sys/sysctl.h> 37 #include <err.h> 38 #include <errno.h> 39 #include <unistd.h> 40 41 #include <atf-c.h> 42 43 #include "h_macros.h" 44 45 /* 46 * A child process cannot call atf functions and expect them to magically 47 * work like in the parent. 48 * The printf(3) messaging from a child will not work out of the box as well 49 * without estabilishing a communication protocol with its parent. To not 50 * overcomplicate the tests - do not log from a child and use err(3)/errx(3) 51 * wrapped with FORKEE_ASSERT()/FORKEE_ASSERTX() as that is guaranteed to work. 52 */ 53 #define FORKEE_ASSERTX(x) \ 54 do { \ 55 int ret = (x); \ 56 if (!ret) \ 57 errx(EXIT_FAILURE, "%s:%d %s(): Assertion failed for: %s", \ 58 __FILE__, __LINE__, __func__, #x); \ 59 } while (0) 60 61 #define FORKEE_ASSERT(x) \ 62 do { \ 63 int ret = (x); \ 64 if (!ret) \ 65 err(EXIT_FAILURE, "%s:%d %s(): Assertion failed for: %s", \ 66 __FILE__, __LINE__, __func__, #x); \ 67 } while (0) 68 69 ATF_TC(attach_pid0); 70 ATF_TC_HEAD(attach_pid0, tc) 71 { 72 atf_tc_set_md_var(tc, "descr", 73 "Assert that a debugger cannot attach to PID 0"); 74 } 75 76 ATF_TC_BODY(attach_pid0, tc) 77 { 78 errno = 0; 79 ATF_REQUIRE_ERRNO(EPERM, ptrace(PT_ATTACH, 0, NULL, 0) == -1); 80 } 81 82 ATF_TC(attach_pid1); 83 ATF_TC_HEAD(attach_pid1, tc) 84 { 85 atf_tc_set_md_var(tc, "descr", 86 "Assert that a debugger cannot attach to PID 1 (as non-root)"); 87 88 atf_tc_set_md_var(tc, "require.user", "unprivileged"); 89 } 90 91 ATF_TC_BODY(attach_pid1, tc) 92 { 93 ATF_REQUIRE_ERRNO(EPERM, ptrace(PT_ATTACH, 1, NULL, 0) == -1); 94 } 95 96 ATF_TC(attach_pid1_securelevel); 97 ATF_TC_HEAD(attach_pid1_securelevel, tc) 98 { 99 atf_tc_set_md_var(tc, "descr", 100 "Assert that a debugger cannot attach to PID 1 with " 101 "securelevel >= 1 (as root)"); 102 103 atf_tc_set_md_var(tc, "require.user", "root"); 104 } 105 106 ATF_TC_BODY(attach_pid1_securelevel, tc) 107 { 108 int level; 109 size_t len = sizeof(level); 110 111 ATF_REQUIRE(sysctlbyname("kern.securelevel", &level, &len, NULL, 0) 112 != -1); 113 114 if (level < 1) { 115 atf_tc_skip("Test must be run with securelevel >= 1"); 116 } 117 118 ATF_REQUIRE_ERRNO(EPERM, ptrace(PT_ATTACH, 1, NULL, 0) == -1); 119 } 120 121 ATF_TC(attach_self); 122 ATF_TC_HEAD(attach_self, tc) 123 { 124 atf_tc_set_md_var(tc, "descr", 125 "Assert that a debugger cannot attach to self (as it's nonsense)"); 126 } 127 128 ATF_TC_BODY(attach_self, tc) 129 { 130 ATF_REQUIRE_ERRNO(EINVAL, ptrace(PT_ATTACH, getpid(), NULL, 0) == -1); 131 } 132 133 ATF_TC(attach_chroot); 134 ATF_TC_HEAD(attach_chroot, tc) 135 { 136 atf_tc_set_md_var(tc, "descr", 137 "Assert that a debugger cannot trace another process unless the " 138 "process's root directory is at or below the tracing process's " 139 "root"); 140 141 atf_tc_set_md_var(tc, "require.user", "root"); 142 } 143 144 ATF_TC_BODY(attach_chroot, tc) 145 { 146 char buf[PATH_MAX]; 147 pid_t child; 148 int fds_toparent[2], fds_fromparent[2]; 149 int rv; 150 uint8_t msg = 0xde; /* dummy message for IPC based on pipe(2) */ 151 152 (void)memset(buf, '\0', sizeof(buf)); 153 ATF_REQUIRE(getcwd(buf, sizeof(buf)) != NULL); 154 (void)strlcat(buf, "/dir", sizeof(buf)); 155 156 ATF_REQUIRE(mkdir(buf, 0500) == 0); 157 ATF_REQUIRE(chdir(buf) == 0); 158 159 ATF_REQUIRE(pipe(fds_toparent) == 0); 160 ATF_REQUIRE(pipe(fds_fromparent) == 0); 161 child = atf_utils_fork(); 162 if (child == 0) { 163 FORKEE_ASSERT(close(fds_toparent[0]) == 0); 164 FORKEE_ASSERT(close(fds_fromparent[1]) == 0); 165 166 FORKEE_ASSERT(chroot(buf) == 0); 167 168 rv = write(fds_toparent[1], &msg, sizeof(msg)); 169 FORKEE_ASSERTX(rv == sizeof(msg)); 170 171 ATF_REQUIRE_ERRNO(EPERM, 172 ptrace(PT_ATTACH, getppid(), NULL, 0) == -1); 173 174 rv = read(fds_fromparent[0], &msg, sizeof(msg)); 175 FORKEE_ASSERTX(rv == sizeof(msg)); 176 177 _exit(0); 178 } 179 ATF_REQUIRE(close(fds_toparent[1]) == 0); 180 ATF_REQUIRE(close(fds_fromparent[0]) == 0); 181 182 printf("Waiting for chrooting of the child PID %d", child); 183 rv = read(fds_toparent[0], &msg, sizeof(msg)); 184 ATF_REQUIRE(rv == sizeof(msg)); 185 186 printf("Child is ready, it will try to PT_ATTACH to parent\n"); 187 rv = write(fds_fromparent[1], &msg, sizeof(msg)); 188 ATF_REQUIRE(rv == sizeof(msg)); 189 190 printf("fds_fromparent is no longer needed - close it\n"); 191 ATF_REQUIRE(close(fds_fromparent[1]) == 0); 192 193 printf("fds_toparent is no longer needed - close it\n"); 194 ATF_REQUIRE(close(fds_toparent[0]) == 0); 195 } 196 197 ATF_TP_ADD_TCS(tp) 198 { 199 setvbuf(stdout, NULL, _IONBF, 0); 200 setvbuf(stderr, NULL, _IONBF, 0); 201 ATF_TP_ADD_TC(tp, attach_pid0); 202 ATF_TP_ADD_TC(tp, attach_pid1); 203 ATF_TP_ADD_TC(tp, attach_pid1_securelevel); 204 ATF_TP_ADD_TC(tp, attach_self); 205 ATF_TP_ADD_TC(tp, attach_chroot); 206 207 return atf_no_error(); 208 } 209